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  • 1.
    Abdul-Hafidh, Esam H.
    et al.
    Taibah Univ Yanbu, Phys Dept, Fac Sci, King Khalid Rd, Al Amoedi 51000, Yanbu El Bahr, Saudi Arabia..
    Abdel-Hafiez, Mahmoud
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Incompressibility of face-centered cubic structure in Metallic Nanosolids2021In: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. 96, no 12, article id 125717Article in journal (Refereed)
    Abstract [en]

    A simple and general theoretical model has been constructed to study the bulk modulus 'B' of FCC nanoparticles and nanostructures. In order to justify the experimental results of the anomalous behavior of B in nanosolids, this method considers the competing effect of both size and shape of a nanoparticle on B. In this work, the relationship between B and the surface energy has been derived based on the dangling bond energy model. The results show that B depends on size, shape and structure of FCC nanocrystalline solids (nanosolids). Our results show that as the shape changes from spherical to deformed, nanosolids become incompressible and B increases as the size decreases. The obtained theoretical results were compared with the experimental predictions for silver, gold and nickel. A very good agreement between theoretical results and experiments was found for silver and nickel. While in gold, we noticed a deviation from the experiment, which is attributed to extreme deformation of the nanogold.

  • 2.
    Ahlberg, Patrik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Johansson, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Zhang, Zhibin
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Jansson, Ulf
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Zhang, Shi-Li
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Lindblad, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Nyberg, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Defect formation in graphene during low-energy ion bombardment2016In: APL Materials, E-ISSN 2166-532X, Vol. 4, no 4, article id 046104Article in journal (Refereed)
    Abstract [en]

    This letter reports on a systematic investigation of sputter induced damage in graphene caused by low energy Ar+ ion bombardment. The integral numbers of ions per area (dose) as well as their energies are varied in the range of a few eV's up to 200 eV. The defects in the graphene are correlated to the dose/energy and different mechanisms for the defect formation are presented. The energetic bombardment associated with the conventional sputter deposition process is typically in the investigated energy range. However, during sputter deposition on graphene, the energetic particle bombardment potentially disrupts the crystallinity and consequently deteriorates its properties. One purpose with the present study is therefore to demonstrate the limits and possibilities with sputter deposition of thin films on graphene and to identify energy levels necessary to obtain defect free graphene during the sputter deposition process. Another purpose is to disclose the fundamental mechanisms responsible for defect formation in graphene for the studied energy range.

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  • 3.
    Amidani, Lucia
    et al.
    Rossendorf Beamline ESRF European Synchrotron, F-38043 Grenoble, France.;Inst Resource Ecol, Helmholtz Zent Dresden Rossendorf, D-01328 Dresden, Germany..
    Dumas, Thomas
    Univ Montpellier, CEA, DES, ISEC, F-30207 Bagnols Sur Ceze, France..
    Shuh, David K.
    Lawrance Berkeley Natl Lab, Berkeley, CA 94720 USA..
    Butorin, Sergei M.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Sahle, Christoph J.
    ESRF, European Synchrotron, F-38043 Grenoble, France..
    Longo, Alessandro
    ESRF, European Synchrotron, F-38043 Grenoble, France..
    Kvashnina, Kristina O.
    Rossendorf Beamline ESRF European Synchrotron, F-38043 Grenoble, France.;Inst Resource Ecol, Helmholtz Zent Dresden Rossendorf, D-01328 Dresden, Germany..
    Oxygen K-Edge X-ray Absorption Spectra of ThO2 and CeO2: Experiment, Interpretation, and Structural Effects2023In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 127, no 6, p. 3077-3084Article in journal (Refereed)
    Abstract [en]

    Experimental oxygen K-edge spectra of ThO2 and CeO2 are presented and interpreted based on density functional theory (DFT). The contribution of d and f orbitals to the O Kedge spectrum is identified as well-distinguished peaks, the presence of which evidences the strong hybridization of Th and Ce metal centers with O orbitals. The sensitivity of the O K-edge to both f- and d-states in the absence of a core-hole on the metal ion results in an insightful overview of the electronic structure involved in the chemical bond. In particular, the large bandwidth of the Th 5f band as compared to the Ce 4f band is observed as a set of wider and more substantial set of peaks in the O K-edge, confirming the stronger hybridization of the former with O orbitals. The peak ascribed to the 5f band of ThO2 is found at higher energy than the 6d band, as predicted from DFT calculations on actinide dioxides. To highlight the sensitivity and the potential use of the O K-edge for the characterization of ThO2-based systems, the sensitivity of the spectrum to structural changes such as lattice expansion and size reduction are calculated and discussed.

  • 4.
    Andaji-Garmaroudi, Zahra
    et al.
    Univ Cambridge, Cavendish Lab, Dept Phys, JJ Thomson Ave, Cambridge CB3 0HE, England..
    Abdi-Jalebi, Mojtaba
    Univ Cambridge, Cavendish Lab, Dept Phys, JJ Thomson Ave, Cambridge CB3 0HE, England.;UCL, Inst Mat Discovery, Torrington Pl, London WC1E 7JE, England..
    Kosasih, Felix U.
    Univ Cambridge, Dept Mat Sci & Met, 27 Charles Babbage Rd, Cambridge CB3 0FS, England..
    Doherty, Tiarnan
    Univ Cambridge, Cavendish Lab, Dept Phys, JJ Thomson Ave, Cambridge CB3 0HE, England..
    Macpherson, Stuart
    Univ Cambridge, Cavendish Lab, Dept Phys, JJ Thomson Ave, Cambridge CB3 0HE, England..
    Bowman, Alan R.
    Univ Cambridge, Cavendish Lab, Dept Phys, JJ Thomson Ave, Cambridge CB3 0HE, England..
    Man, Gabriel
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Cappel, Ute B.
    KTH Royal Inst Technol, Dept Chem, Div Appl Phys Chem, SE-10044 Stockholm, Sweden..
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Ducati, Caterina
    Univ Cambridge, Dept Mat Sci & Met, 27 Charles Babbage Rd, Cambridge CB3 0FS, England..
    Friend, Richard H.
    Univ Cambridge, Cavendish Lab, Dept Phys, JJ Thomson Ave, Cambridge CB3 0HE, England..
    Stranks, Samuel D.
    Univ Cambridge, Cavendish Lab, Dept Phys, JJ Thomson Ave, Cambridge CB3 0HE, England.;Univ Cambridge, Dept Chem Engn & Biotechnol, Philippa Fawcett Dr, Cambridge CB3 0AS, England..
    Elucidating and Mitigating Degradation Processes in Perovskite Light-Emitting Diodes2020In: Advanced Energy Materials, ISSN 1614-6832, E-ISSN 1614-6840, Vol. 10, no 48, article id 2002676Article in journal (Refereed)
    Abstract [en]

    Halide perovskites have attracted substantial interest for their potential as disruptive display and lighting technologies. However, perovskite light-emitting diodes (PeLEDs) are still hindered by poor operational stability. A fundamental understanding of the degradation processes is lacking but will be key to mitigating these pathways. Here, a combination of in operando and ex situ measurements to monitor the performance degradation of (Cs(0.06)FA(0.79)MA(0.15))Pb(I0.85Br0.15)(3) PeLEDs over time is used. Through device, nanoscale cross-sectional chemical mapping, and optical spectroscopy measurements, it is revealed that the degraded performance arises from an irreversible accumulation of bromide content at one interface, which leads to barriers to injection of charge carriers and thus increased nonradiative recombination. This ionic segregation is impeded by passivating the perovskite films with potassium halides, which immobilizes the excess halide species. The passivated PeLEDs show enhanced external quantum efficiency (EQE) from 0.5% to 4.5% and, importantly, show significantly enhanced stability, with minimal performance roll-off even at high current densities (>200 mA cm(-2)). The decay half-life for the devices under continuous operation at peak EQE increases from <1 to approximate to 15 h through passivation, and approximate to 200 h under pulsed operation. The results provide generalized insight into degradation pathways in PeLEDs and highlight routes to overcome these challenges.

  • 5.
    Andersson, Edvin
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Sångeland, Christofer
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Berggren, Elin
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Johansson, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Kühn, Danilo
    Lindblad, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Mindemark, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Polymer Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Hahlin, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Early-Stage Decomposition of Solid Polymer Electrolytes in Li-Metal Batteries2021In: Journal of Materials Chemistry, ISSN 0959-9428, E-ISSN 1364-5501, Vol. 9, no 39Article in journal (Refereed)
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  • 6.
    Arneth, J.
    et al.
    Heidelberg Univ, Kirchhoff Inst Phys, INF 227, D-69120 Heidelberg, Germany..
    Jonak, M.
    Heidelberg Univ, Kirchhoff Inst Phys, INF 227, D-69120 Heidelberg, Germany..
    Spachmann, S.
    Heidelberg Univ, Kirchhoff Inst Phys, INF 227, D-69120 Heidelberg, Germany..
    Abdel-Hafiez, Mahmoud
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials. Natl Univ Sci & Technol MISiS, Moscow 119049, Russia..
    Kvashnin, Yaroslav
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Klingeler, R.
    Heidelberg Univ, Kirchhoff Inst Phys, INF 227, D-69120 Heidelberg, Germany..
    Uniaxial pressure effects in the two-dimensional van der Waals ferromagnet CrI32022In: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 105, no 6, article id L060404Article in journal (Refereed)
    Abstract [en]

    Magnetoelastic coupling and uniaxial pressure dependencies of the ferromagnetic ordering temperature in the quasi-two-dimensional layered van der Waals material CrI3 are experimentally studied and quantified by high-resolution dilatometry. Clear anomalies in the thermal expansion coefficients at T-C imply positive (negative) pressure dependencies partial derivative T-C/partial derivative p(i) for pressure applied along (perpendicular to) the c axis. The experimental results are backed up by numerical studies showing that the dominant, intralayer magnetic coupling increases upon compression along the c direction and decreases with negative in-plane strain. In contrast, interlayer exchange is shown to initially increase and subsequently decrease upon the application of both out-of-plane and in-plane compression.

  • 7. Aryal, Um Kanta
    et al.
    Pazniak, Hanna
    Kumari, Tanya
    Weber, Matthieu
    Johansson, Fredrik O. L.
    Vannucchi, Noemi
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials. Institut des Nanosciences de Paris, Sorbonne Universite, UMR CNRS 7588, F-75005 Paris, France..
    Witkowski, Nadine
    Turkovic, Vida
    Di Carlo, Aldo
    Madsen, Morten
    2D MXene-Based Electron Transport Layers for Nonhalogenated Solvent-Processed Stable Organic Solar Cells2023In: ACS Applied Energy Materials, E-ISSN 2574-0962, Vol. 6, no 9, p. 4549-4558Article in journal (Refereed)
    Abstract [en]

    Implementation of 2D materials is one of the promising routes for improving the efficiency and stability of organic solar cells (OSCs). Due to their tunable optical and electronic properties, MXenes, a family of 2D transition metal carbides and nitrides, have attracted considerable attention and demonstrated their potential for next-generation solar cells. In this work, Ti3C2Tx MXene was added into ZnO precursors and applied as a modified composite electron transport layer (ETL) in PM6:N3-based inverted OSCs. The nonhalogenated solvent o- xylene was employed as the active layer solvent for the development of stable, efficient, and eco-friendly OSCs. By optimizing the concentration of Ti3C2Tx in the ZnO ETL, the solar cells exhibited power conversion efficiencies (PCEs) of 14.1 and 13.7% for 0.5 and 2 wt % MXene, respectively, as compared to neat ZnO layer devices with a PCE of 14.9%. Interestingly, the MXene-based PM6:N3 OSC devices showed superior device stability compared to the reference cells. It is demonstrated that the MXene introduced in the composite ZnO-based ETL mitigates the photocatalytic decomposition of the organic active layer on the ZnO surface, as analyzed via optical spectroscopy and hard X-ray photoelectron spectroscopy, which appears as a main reason for improved device stability. We thus report on the usage of MXene in green solvent-processed OSCs to enhance the lifetime of solar cells and thus address an important bottleneck in high-performance nonfullerene acceptor solar cells.

  • 8.
    Barakat, M. M. E.
    et al.
    Taibah Univ, Fac Sci, Dept Phys, Yanbu, Saudi Arabia.;Alexandria Univ, Fac Sci, Dept Phys, Alexandria, Egypt..
    Abdel-Baset, T. A.
    Taibah Univ, Fac Sci, Dept Phys, Yanbu, Saudi Arabia.;Fayoum Univ, Fac Sci, Dept Phys, Al Fayyum, Egypt..
    Belhaj, M.
    Bakeer, D. El-Said
    Taibah Univ, Fac Sci & Arts, Dept Phys, Al Ula, Saudi Arabia.;Damanhour Univ, Fac Sci, Dept Phys, Damnhour, Egypt..
    Vasiliev, A. N.
    Lomonosov Moscow State Univ, Moscow 119991, Russia.;Natl Univ Sci & Technol MISiS, Moscow 119049, Russia..
    Abdel-Hafiez, Mahmoud
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials. Uppsala Univ, Dept Phys & Astron, Box 516, SE-75120 Uppsala, Sweden.;Univ Sharjah, Dept Appl Phys & Astron, POB 27272, Sharjah, U Arab Emirates..
    Superconducting gap and critical behavior in the Iron-Pnictides2023In: RESULTS IN PHYSICS, ISSN 2211-3797, Vol. 52, article id 106832Article in journal (Refereed)
    Abstract [en]

    In the phase diagram of iron pnictides, superconductivity arises at the border of antiferromagnetism, which raises the question of the role of symmetry of the gap and quantum criticality. Although more than 15-years of extensive research, the microscopic origin of the pairing symmetry inside the superconducting (SC) dome and its link to quantum criticality still remains elusive. Here, we report two new findings on BaFe2_xNixAs2: (1) A sharp peak in the x-dependence of the lower and upper critical fields, the SC critical current density Jc, the size of the jump in the specific heat Delta Cel/T and the Sommerfeld coefficient (gamma) at the optimum composition x = 0.10, where the SC transition temperature Tc reaches a maximum. Our obtained reliable values as a function of doping of the normal-state Sommerfeld coefficient increase with doping, illustrating the strong competition between magnetism and superconductivity and attributed to closing of spin density wave gap with Ni doping. (2) We show that doping induced a sudden change of the gap structure from nodeless to nodal. Our results imply that the superconductivity in BaFe2_xNixAs2 is closely linked to the quantum criticality and is characterized by a complex order parameter.

  • 9.
    Belotcerkovtceva, Daria
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Intricacies, Endurance, and Performance Enhancement in Graphene Devices: Towards 2D electronic and spintronic circuits2024Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Graphene, the atomically thin material of carbon atoms, first isolated experimentally in 2004, exhibits remarkable properties and holds potential for applications in quantum, electrical, and spin-based devices. The chemical vapor deposition (CVD) method enables graphene production on a large scale, merging its exceptional characteristics with scalability and high-quality implementation. Despite the extraordinary promise of CVD graphene with structural imperfections, the main challenge for graphene electronics and spintronics lies in achieving reliability at the device and circuit levels with scalable materials and interfaces. To address these, it is essential to understand the intricacies, endurance, and performance issues in graphene devices. In this thesis, to understand graphene interfaces in devices, we first explored a critical aspect of graphene's interaction with metal oxides, particularly titanium oxide (TiOx) and aluminum oxide (AlOx), and their implications for graphene-based nanoelectronic and spintronic devices. Investigating the electrical characteristics of graphene, both with and without oxides, uncovers the distinct behaviors of TiOx and AlOx when interfaced with graphene, highlighting the charge transfer-induced p-type doping and the formation of sp3 defects, traps, and impurities, especially at the AlOx/graphene interface. These findings bring new insights for graphene spintronic devices while opening possibilities for novel functionalities such as hybrid resistive switching devices. Advancing further towards van der Waals heterostructures in these studies, we could also observe the impact of monolayer MoS2 on graphene’s properties. Next, we explored how CVD graphene devices withstand high current stress to elucidate device durability and resilience. We examine the impact of extreme electric currents on channel structures and resistive tunnel barrier interfaces, focusing on their feasibility for high-capacity electronic and spintronic applications. Here, despite the polycrystalline nature of CVD graphene, we could observe the highest current density of 5.2×108 Acm-2 in graphene on Si/SiO2 substrates, elevating it further to 1.7×109 Acm-2 on diamond substrates, remarkably exceeding previous reports. Performing systematic cyclic electrical measurements, with a gradual increase in the applied high current, we could determine the limits of the reversible regime for safe device operation of both channels and contacts. This knowledge of high current limits and oxide interfaces with graphene leads to an innovative current-treated passive graphene (CTPG) system, where we passivated graphene with metal oxide and applied high current to enhance quality. This method addresses the challenge of interfacial defects and remarkably improves carrier mobility, thereby reducing Coulomb scattering while mitigating electromigration issues. The CTPG presents a scalable platform for stable nanoelectronic and spintronic circuits. The experiments and systems studied in this thesis open possibilities for the exploration of temperature-dependent charge and spin transport measurements via new heterostructures and interfaces with different material combinations.

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  • 10.
    Belotcerkovtceva, Daria
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Intricacy and Stability of Graphene Spintronic Devices2023Licentiate thesis, monograph (Other academic)
    Abstract [en]

    Graphene, the first experimentally isolated atomically thin crystal has displayed numerous superlative properties for quantum and spin-based electronics, as evidenced by research results of more than a decade. The scalable form of graphene, produced by the chemical vapor deposition (CVD) method has been increasingly attracting scientific and technological interest, as outstanding properties are combined with large scalability and high quality. The high-performance devices based on large-scale polycrystalline graphene growth capabilities with efficient charge and spin transport make it prospective for practical implementation into future spintronic and quantum integrated circuits. While CVD graphene presents unlimited prospects for exploring spin currents, there exist challenges along the way in terms of scalability of efficient performance, and reliability. Deformations, wrinkles, and structural (electronic) modifications caused at the interfaces with contacts remain key concerns for device performance. In particular, oxide-based interfaces with graphene are central to both graphenes electronic and spintronic devices. For high-performance scalable devices, it is of crucial significance to understand the details of these interfaces and how devices of CVD graphene with polycrystallinity respond to high current limits. In this thesis, we discuss a systematic study of the effect of e-beam evaporated ultra-thin titanium oxide (TiOx) and aluminum oxide (AlOx) on graphene; which are conventionally used as tunnel barriers in spintronic and nanoelectronics devices. Characteristic topographic features of both metal oxides on the graphene surface were revealed by atomic force microscopy. To estimate the impact of these oxides on graphene, electrical measurements were performed on graphene spin devices with and without metal oxides on the same devices. These measurements show significant p-type doping for both metal oxides, with sustained sheet conductance (σ0) and mobility (μ) values. Strikingly, Raman spectroscopy and X-ray photoelectron spectroscopy show the emergence of significant sp3 carbon for AlOx on graphene, in sharp contrast to TiOx. Our results and observations, together with theoretical calculations provide new insights into how sp3 carbon for AlOx can lead to new memristive mechanisms and explicate enhanced spin relaxation into graphene with AlOx devices, which was widely attributed to the presence of interface pinholes. Here we also investigate how CVD graphene-based devices respond to high current stress to understand their stability and robustness. Despite the grainy and wrinkled structure, we observed the highest till-date current density of 5.2 × 108 A/cm2, remarkably higher than previously reported values for multilayer graphene and graphene nanoribbons. The recorded reversible regime (~108 A/cm2) for device operation allows reliable spin transport measurements with an observable spin signal up at such high current density. Furthermore, our investigation also encompasses cyclical current-voltage electrical measurement, to unveil the stability of graphene/ultra-thin oxide interfaces in graphene devices. Overall, these results present significance for CVD graphene device engineering for nanoelectronics and spintronics.

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  • 11.
    Belotcerkovtceva, Daria
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Panda, J.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Ramu, M.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering.
    Sarkar, Tapati
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Noumbe, Ulrich
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Kamalakar, M. Venkata
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    High current limits in chemical vapor deposited graphene spintronic devices2023In: Nano Reseach, ISSN 1998-0124, E-ISSN 1998-0000, Vol. 16, no 4, p. 4233-4239Article in journal (Refereed)
    Abstract [en]

    Understanding the stability and current-carrying capacity of graphene spintronic devices is key to their applications in graphene channel-based spin current sensors, spin-torque oscillators, and potential spin-integrated circuits. However, despite the demonstrated high current densities in exfoliated graphene, the current-carrying capacity of large-scale chemical vapor deposited (CVD) graphene is not established. Particularly, the grainy nature of chemical vapor deposited graphene and the presence of a tunnel barrier in CVD graphene spin devices pose questions about the stability of high current electrical spin injection. In this work, we observe that despite structural imperfections, CVD graphene sustains remarkably highest currents of 5.2 × 108 A/cm2, up to two orders higher than previously reported values in multilayer CVD graphene, with the capacity primarily dependent upon the sheet resistance of graphene. Furthermore, we notice a reversible regime, up to which CVD graphene can be operated without degradation with operating currents as high as 108 A/cm2, significantly high and durable over long time of operation with spin valve signals observed up to such high current densities. At the same time, the tunnel barrier resistance can be modified by the application of high currents. Our results demonstrate the robustness of large-scale CVD graphene and bring fresh insights for engineering and harnessing pure spin currents for innovative device applications. 

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  • 12.
    Berggren, Elin
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Weng, Yi-Chen
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Li, Qifan
    Linköping Univ, Dept Sci & Technol, Lab Organ Elect, SE-60174 Norrköping, Sweden..
    Yang, Chi-Yuan
    Linköping Univ, Dept Sci & Technol, Lab Organ Elect, SE-60174 Norrköping, Sweden..
    Johansson, Fredrik O. L.
    KTH Royal Inst Technol, Dept Chem, Div Appl Phys Chem, SE-10044 Stockholm, Sweden.;Sorbonne Univ, Inst Nanosci Paris, CNRS, INSP, F-75005 Paris, France..
    Cappel, Ute B.
    KTH Royal Inst Technol, Dept Chem, Div Appl Phys Chem, SE-10044 Stockholm, Sweden..
    Berggren, Magnus
    Linköping Univ, Dept Sci & Technol, Lab Organ Elect, SE-60174 Norrköping, Sweden..
    Fabiano, Simone
    Linköping Univ, Dept Sci & Technol, Lab Organ Elect, SE-60174 Norrköping, Sweden..
    Lindblad, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Charge Transfer in the P(g42T-T):BBL Organic Polymer Heterojunction Measured with Core-Hole Clock Spectroscopy2023In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 127, no 49, p. 23733-23742Article in journal (Refereed)
    Abstract [en]

    The conductivity of organic polymer heterojunction devices relies on the electron dynamics occurring along interfaces between the acceptor and donor moieties. To investigate these dynamics with chemical specificity, spectroscopic techniques are employed to obtain localized snapshots of the electron behavior at selected interfaces. In this study, charge transfer in blends (by weight 10, 50, 90, and 100%) of p-type polymer P(g(4)2T-T) (bithiophene-thiophene) and n-type polymer BBL (poly(benzimidazo-benzo-phenanthroline)) was measured by resonant Auger spectroscopy. Electron spectra emanating from the decay of core-excited states created upon X-ray absorption in the donor polymer P(g(4)2T-T) were measured in the sulfur KL2,3L2,3 Auger kinetic energy region as a function of the excitation energy. By tuning the photon energy across the sulfur K-absorption edge, it is possible to differentiate between decay paths in which the core-excited electron remained on the atom with the core-hole and those where it tunneled away. Analyzing the competing decay modes of these localized and delocalized (charge-transfer) processes facilitated the computation of charge-transfer times as a function of excitation energy using the core-hole clock method. The electron delocalization times derived from the measurements were found to be in the as/fs regime for all polymer blends, with the fastest charge transfer occurring in the sample with an equal amount of donor and acceptor polymer. These findings highlight the significance of core-hole clock spectroscopy as a chemically specific tool for examining the local charge tunneling propensity, which is fundamental to understanding macroscopic conductivity. Additionally, the X-ray absorption spectra near the sulfur K-edge in the P(g(4)2T-T) polymer for different polymer blends were analyzed to compare molecular structure, orientation, and ordering in the polymer heterojunctions. The 50% donor sample exhibited the most pronounced angular dependence of absorption, indicating a higher level of ordering compared to the other weight blends. Our studies on the electron dynamics of this type of all-polymer donor-acceptor systems, in which spontaneous ground-state electron transfer occurs, provide us with critical insights to further advance the next generation of organic conductors with mixed electron-hole conduction characteristics suitable for highly stable electrodes of relevance for electronic, electrochemical, and optoelectronic applications.

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  • 13.
    Bericat Vadell, Robert
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Sekar, Pandiaraj
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
    Patehebieke, Yeersen
    Univ Gothenburg, Dept Chem & Mol Biol, Kemivagen 10, S-41258 Gothenburg, Sweden..
    Zou, Xianshao
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Kaul, Nidhi
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Broqvist, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Lindblad, Rebecka
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Lindblad, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Arkhypchuk, Anna I.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Synthetic Molecular Chemistry.
    Walletin, Carl-Johan
    Univ Gothenburg, Dept Chem & Mol Biol, Kemivagen 10, S-41258 Gothenburg, Sweden..
    Sá, Jacinto
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry. Polish Acad Sci, Inst Phys Chem, Marcina Kasprzaka 44-52, PL-01224 Warsaw, Poland..
    Single-electron transfer reactions on surface-modified gold plasmons2023In: Materials Today Chemistry, E-ISSN 2468-5194, Vol. 34, article id 101783Article in journal (Refereed)
    Abstract [en]

    Photoredox catalysis's relevance in organic synthesis research and innovation will increase in the coming decades. However, the processes rely almost exclusively on expensive noble metal complexes, most notably iridium complexes, to absorb light and transfer a single charge to a substrate or a catalyst to initiate cascade transformations. Light-triggered plasmon resonances generate a non-Fermi-Dirac energy distribution with many hot carriers that decay in similar to 1 ps. Their ultrafast relaxation makes performing single electron transfer (SET) transformations challenging. Herein, a novel photosystem is proposed based on surface-modified gold nanoparticles (aka plasmon "molecularization"), which improved charge separation and, more importantly, enabled SET reactions, expanding the portfolio of photocatalysts available for photoredox catalysis. The photosystem was made into an electrode, permitting its use in photoelectrochemical arrangements that leverage electro- and photo-chemical approaches' benefits and chemical engineering solutions, helping the synthetic chemistry efforts towards greener synthesis and synthesis of more complex structures on a scale.

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  • 14.
    Bijedic, Adi
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Chemical and Bio-Molecular Physics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials. Man.
    Sustaining Orientation of Ubiquitin for Single Particle Imaging Using Electric Fields2021Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Single-particle imaging, or SPI, is a method used to obtain the three-dimensional structure of particles. Repeatedly aiming X-rays at samples of a particle produces diffraction patterns, which are combined to a best-fit three-dimensional model of the particle. SPI of proteins can be improved by orienting the protein before imaging. Protein dipole orientation makes use of a protein's dipole moment and an external electric field to generate torque, which can orient the protein. A protein subject to an electric field may however result in damage of the protein's geometrical structure, or insufficient protein orientation, depending on the magnitude of the electric field.

    Sufficient protein orientation without substantial protein damage is possible in an interval of electric field strengths. The results in this report reveal that the method of SPI can be further improved. With a protein being fully oriented in an electric field, it is possible to reduce the electric field strength and yet sustain sufficient orientation, with some constraints. Longer times for imaging and less structural damage to the protein are hence possible. This study implements Molecular Dynamics (MD) and the most extensively used open-source MD software, GROMACS, with ubiquitin as a sample protein.

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  • 15.
    Bonifacio, Agathe
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Electronic Properties of Graphene2021Student paper second term, 10 credits / 15 HE creditsStudent thesis
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  • 16.
    Born, Artur
    et al.
    Uppsala Berlin Joint Lab Next Generat Photoelect, Albert Einstein Str 15, D-12489 Berlin, Germany.;Helmholtz Zentrum Berlin Mat & Energie, Inst Methods & Instrumentat Synchrotron Radiat Re, Albert Einstein Str 15, D-12489 Berlin, Germany.;Univ Potsdam, Inst Phys & Astronom, Karl Liebknecht Str 24-25, D-14476 Potsdam, Germany.
    Johansson, Fredrik O. L.
    KTH Royal Inst Technol, Div Appl Phys Chem, Dept Chem, SE-10044 Stockholm, Sweden.;Sorbonne Univ, CNRS, Inst NanoSci Paris, INSP, F-75005 Paris, France.
    Leitner, Torsten
    Uppsala Berlin Joint Lab Next Generat Photoelect, Albert Einstein Str 15, D-12489 Berlin, Germany.;Helmholtz Zentrum Berlin Mat & Energie, Inst Methods & Instrumentat Synchrotron Radiat Re, Albert Einstein Str 15, D-12489 Berlin, Germany.
    Bidermane, Ieva
    Uppsala Berlin Joint Lab Next Generat Photoelect, Albert Einstein Str 15, D-12489 Berlin, Germany.;Helmholtz Zentrum Berlin Mat & Energie, Inst Methods & Instrumentat Synchrotron Radiat Re, Albert Einstein Str 15, D-12489 Berlin, Germany.
    Kuehn, Danilo
    Uppsala Berlin Joint Lab Next Generat Photoelect, Albert Einstein Str 15, D-12489 Berlin, Germany.;Helmholtz Zentrum Berlin Mat & Energie, Inst Methods & Instrumentat Synchrotron Radiat Re, Albert Einstein Str 15, D-12489 Berlin, Germany.
    Mårtensson, Nils
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials. Uppsala Berlin Joint Lab Next Generat Photoelect, Albert Einstein Str 15, D-12489 Berlin, Germany.
    Foehlisch, Alexander
    Uppsala Berlin Joint Lab Next Generat Photoelect, Albert Einstein Str 15, D-12489 Berlin, Germany.;Helmholtz Zentrum Berlin Mat & Energie, Inst Methods & Instrumentat Synchrotron Radiat Re, Albert Einstein Str 15, D-12489 Berlin, Germany.;Univ Potsdam, Inst Phys & Astronom, Karl Liebknecht Str 24-25, D-14476 Potsdam, Germany.
    The degree of electron itinerancy and shell closing in the core-ionized state of transition metals probed by Auger-photoelectron coincidence spectroscopy2022In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 24, no 32, p. 19218-19222Article in journal (Refereed)
    Abstract [en]

    Auger-photoelectron coincidence spectroscopy (APECS) has been used to examine the electron correlation and itinerance effects in transition metals Cu, Ni and Co. It is shown that the LVV Auger, in coincidence with 2p photoelectrons, spectra can be represented using atomic multiplet positions if the 3d-shell is localized (atomic-like) and with a self-convoluted valence band for band-like (itinerant) materials as explained using the Cini-Sawatzky model. For transition metals, the 3d band changes from band-like to localized with increasing atomic number, with the possibility of a mixed behavior. Our result shows that the LVV spectra of Cu can be represented by atomic multiplet calculations, those of Co resemble the self-convolution of the valence band and those of Ni are a mixture of both, consistent with the Cini-Sawatzky model.

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  • 17.
    Born, Artur
    et al.
    Uppsala Berlin Joint Lab Next Generat Photoelectr, Albert Einstein Str 15, D-12489 Berlin, Germany.;Helmholtz Zentrum Berlin Mat & Energie, Inst Methods & Instrumentat Synchrotron Radiat Re, Albert Einstein Str 15, D-12489 Berlin, Germany.;Univ Potsdam, Inst Phys & Astron, Karl Liebknecht Str 24-25, D-14476 Potsdam, Germany..
    Johansson, Fredrik O. L.
    Uppsala Berlin Joint Lab Next Generat Photoelectr, Albert Einstein Str 15, D-12489 Berlin, Germany.;Helmholtz Zentrum Berlin Mat & Energie, Inst Methods & Instrumentat Synchrotron Radiat Re, Albert Einstein Str 15, D-12489 Berlin, Germany.;Univ Potsdam, Inst Phys & Astron, Karl Liebknecht Str 24-25, D-14476 Potsdam, Germany..
    Leitner, Torsten
    Uppsala Berlin Joint Lab Next Generat Photoelectr, Albert Einstein Str 15, D-12489 Berlin, Germany.;Helmholtz Zentrum Berlin Mat & Energie, Inst Methods & Instrumentat Synchrotron Radiat Re, Albert Einstein Str 15, D-12489 Berlin, Germany..
    Kuehn, Danilo
    Uppsala Berlin Joint Lab Next Generat Photoelectr, Albert Einstein Str 15, D-12489 Berlin, Germany.;Helmholtz Zentrum Berlin Mat & Energie, Inst Methods & Instrumentat Synchrotron Radiat Re, Albert Einstein Str 15, D-12489 Berlin, Germany..
    Lindblad, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics. Uppsala Berlin Joint Lab Next Generat Photoelectr, Albert Einstein Str 15, D-12489 Berlin, Germany..
    Mårtensson, Nils
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics. Uppsala Berlin Joint Lab Next Generat Photoelectr, Albert Einstein Str 15, D-12489 Berlin, Germany..
    Foehlisch, Alexander
    Uppsala Berlin Joint Lab Next Generat Photoelectr, Albert Einstein Str 15, D-12489 Berlin, Germany.;Helmholtz Zentrum Berlin Mat & Energie, Inst Methods & Instrumentat Synchrotron Radiat Re, Albert Einstein Str 15, D-12489 Berlin, Germany.;Univ Potsdam, Inst Phys & Astron, Karl Liebknecht Str 24-25, D-14476 Potsdam, Germany..
    Separation of surface oxide from bulk Ni by selective Ni 3p photoelectron spectroscopy for chemical analysis in coincidence with Ni M-edge Auger electrons2021In: Scientific Reports, E-ISSN 2045-2322, Vol. 11, no 1, article id 16596Article in journal (Refereed)
    Abstract [en]

    The chemical shift of core level binding energies makes electron spectroscopy for chemical analysis (ESCA) a workhorse analytical tool for science and industry. For some elements, close lying and overlapping spectral features within the natural life time broadening restrict applications. We establish how the core level binding energy chemical shift can be picked up experimentally by the additional selectivity through Auger electron photoelectron coincidence spectroscopy (APECS). Coincident measurement of Ni 3p photoemission with different MVV Auger regions from specific decay channels, narrows the 3p core-levels to a width of 1.2 eV, resolves the spin-orbit splitting of 1.6 eV and determines the chemical shift of Ni 3p levels of a Ni(111) single crystal and its oxidized surface layer to 0.6 eV.

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  • 18.
    Bretscher, Hope
    et al.
    Univ Cambridge, Cambridge CB2 1TN, England..
    Li, Zhaojun
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials. Univ Cambridge, Cambridge CB2 1TN, England.
    Xiao, James
    Univ Cambridge, Cambridge CB2 1TN, England..
    Qiu, Diana Yuan
    Yale Univ, New Haven, CT 06520 USA..
    Refaely-Abramson, Sivan
    Weizmann Inst Sci, IL-76100 Rehovot, Israel..
    Alexander-Webber, Jack A.
    Univ Cambridge, Cambridge CB2 1TN, England..
    Tanoh, Arelo
    Univ Cambridge, Cambridge CB2 1TN, England..
    Fan, Ye
    Univ Cambridge, Cambridge CB2 1TN, England..
    Delport, Geraud
    Univ Cambridge, Cambridge CB2 1TN, England..
    Williams, Cyan A.
    Univ Cambridge, Cambridge CB2 1TN, England..
    Stranks, Samuel D.
    Univ Cambridge, Cambridge CB2 1TN, England..
    Hofmann, Stephan
    Univ Cambridge, Cambridge CB2 1TN, England..
    Neaton, Jeffrey B.
    Univ Calif Berkeley, Berkeley, CA 94720 USA.;Lawrence Berkeley Natl Lab, Berkeley, CA 94720 USA..
    Louie, Steven G.
    Univ Calif Berkeley, Berkeley, CA 94720 USA.;Lawrence Berkeley Natl Lab, Berkeley, CA 94720 USA..
    Rao, Akshay
    Univ Cambridge, Cambridge CB2 1TN, England..
    Rational Passivation of Sulfur Vacancy Defects in Two-Dimensional Transition Metal Dichalcogenides2021In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 15, no 5, p. 8780-8789Article in journal (Refereed)
    Abstract [en]

    Structural defects vary the optoelectronic properties of monolayer transition metal dichalcogenides, leading to concerted efforts to control defect type and density via materials growth or postgrowth passivation. Here, we explore a simple chemical treatment that allows on-off switching of low-lying, defect-localized exciton states, leading to tunable emission properties. Using steady-state and ultrafast optical spectroscopy, supported by ab initio calculations, we show that passivation of sulfur vacancy defects, which act as exciton traps in monolayer MoS2 and WS2, allows for controllable and improved mobilities and an increase in photoluminescence up to 275-fold, more than twice the value achieved by other chemical treatments. Our findings suggest a route for simple and rational defect engineering strategies for tunable and switchable electronic and excitonic properties through passivation.

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  • 19.
    Butorin, Sergei
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Advanced x-ray spectroscopy of actinide trichlorides2021In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 155, no 16, article id 164103Article in journal (Refereed)
    Abstract [en]

    The application of core-to-core (3d-to-4f) resonant inelastic x-ray scattering (RIXS) and high-energy-resolution fluorescence-detected x-ray absorption (HERFD-XAS) at actinide M-4,M-5 edges, as techniques with the enhanced sensitivity to changes in the chemical state, was analyzed for trivalent actinide compounds. As an example, a series of actinide chlorides AnCl(3) (An = U, Np, Pu, Am, Cm, Bk, and Cf) was used. The crystal-field multiplet formalism was applied to calculate the 3d-4f RIXS maps, and the HERFD-XAS spectra were extracted as cuts of these RIXS maps along the incident energy axis at the constant emitted energy, corresponding to the maximum of the RIXS intensity. A relation between HERFD and conventional XAS methods was also examined. Despite some differences between profiles of the An M-5 HERFD and conventional XAS spectra of trivalent actinides, the results of calculations indicate that the HERFD method can be used at the An M-5 edge for monitoring even small variations in the An chemical state. As a whole, better agreement between the HERFD and XAS spectra was found for the An M-4 edges as compared to the An M-5 edges. By using the point charge electrostatic model, the dependence of the An M-4,M-5 HERFD-XAS spectra on the An coordination number was studied, which indicates the significant sensitivity of the distribution of the An 5f states to the ligand structural arrangement around the An sites.

  • 20.
    Butorin, Sergei
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Bauters, Stephen
    Helmholtz Zentrum Dresden Rossendorf HZDR, Inst Resource Ecol, POB 510119, D-01314 Dresden, Germany.;Rossendorf Beamline ESRF European Synchrotron, F-38043 Grenoble, France..
    Amidani, Lucia
    Helmholtz Zentrum Dresden Rossendorf HZDR, Inst Resource Ecol, POB 510119, D-01314 Dresden, Germany.;Rossendorf Beamline ESRF European Synchrotron, F-38043 Grenoble, France..
    Beck, Aaron
    Karlsruhe Inst Technol, Inst Nucl Waste Disposal INE, PO 3640, D-76021 Karlsruhe, Germany..
    Rossberg, Andre
    Helmholtz Zentrum Dresden Rossendorf HZDR, Inst Resource Ecol, POB 510119, D-01314 Dresden, Germany.;Rossendorf Beamline ESRF European Synchrotron, F-38043 Grenoble, France..
    Weiss, Stephan
    Helmholtz Zentrum Dresden Rossendorf HZDR, Inst Resource Ecol, POB 510119, D-01314 Dresden, Germany..
    Vitova, Tonya
    Karlsruhe Inst Technol, Inst Nucl Waste Disposal INE, PO 3640, D-76021 Karlsruhe, Germany..
    Kvashnina, Kristina O.
    Helmholtz Zentrum Dresden Rossendorf HZDR, Inst Resource Ecol, POB 510119, D-01314 Dresden, Germany.;Rossendorf Beamline ESRF European Synchrotron, F-38043 Grenoble, France..
    Tougait, Olivier
    Univ Lille, Univ Artois, UCCS Unite Catalyse & Chim Solide, CNRS,UMR 8181,Cent Lille, F-59000 Lille, France..
    Effect of carbon content on electronic structure of uranium carbides2023In: Scientific Reports, E-ISSN 2045-2322, Vol. 13, article id 20434Article in journal (Refereed)
    Abstract [en]

    The electronic structure of UCx (x = 0.9, 1.0, 1.1, 2.0) was studied by means of x-ray absorption spectroscopy (XAS) at the CK edge and measurements in the high energy resolution fluorescence detection (HERFD) mode at the U M-4 and L-3 edges. The full-relativistic density functional theory calculations taking into account the 5f - 5f Coulomb interaction U and spin-orbit coupling (DFT+U+SOC) were also performed for UCand UC2. While the U L-3 HERFD-XAS spectra of the studied samples reveal little difference, the U M-4 HERFD-XAS spectra show certain sensitivity to the varying carbon content in uranium carbides. The observed gradual changes in the U M-4 HERFD spectra suggest an increase in the C2p-U 5f charge transfer, which is supported by the orbital population analysis in the DFT+U+ SOC calculations, indicating an increase in the U 5f occupancy in UC2 as compared to that in UC. On the other hand, the density of states at the Fermi level were found to be significantly lower in UC2, thus affecting the thermodynamic properties. Both the x-ray spectroscopic data (in particular, the CK XAS measurements) and results of the DFT+U+SOC calculations indicate the importance of taking into account U and SOC for the description of the electronic structure of actinide carbides.

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  • 21.
    Butorin, Sergei
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Bauters, Stephen
    Helmholtz Zentrum Dresden Rossendorf HZDR, Inst Resource Ecol, POB 510119, D-01314 Dresden, Germany.;Rossendorf Beamline ESRF European Synchrotron, CS40220, F-38043 Grenoble 9, France..
    Amidani, Lucia
    Helmholtz Zentrum Dresden Rossendorf HZDR, Inst Resource Ecol, POB 510119, D-01314 Dresden, Germany.;Rossendorf Beamline ESRF European Synchrotron, CS40220, F-38043 Grenoble 9, France..
    Beck, Aaron
    Karlsruhe Inst Technol, Inst Nucl Waste Disposal INE, PO 3640, D-76021 Karlsruhe, Germany..
    Weiss, Stephan
    Helmholtz Zentrum Dresden Rossendorf HZDR, Inst Resource Ecol, POB 510119, D-01314 Dresden, Germany..
    Vitova, Tonya
    Karlsruhe Inst Technol, Inst Nucl Waste Disposal INE, PO 3640, D-76021 Karlsruhe, Germany..
    Tougait, Olivier
    Univ Lille, CNRS, Cent Lille, Univ Artois,UMR 8181,UCCS Unite Catalyse & Chim S, F-59000 Lille, France..
    X-ray spectroscopic study of chemical state in uranium carbides2022In: Journal of Synchrotron Radiation, ISSN 0909-0495, E-ISSN 1600-5775, Vol. 29, p. 295-302Article in journal (Refereed)
    Abstract [en]

    UC and UMeC2 (Me = Fe, Zr, Mo) carbides were studied by the high-energyresolution fluorescence-detected X-ray absorption (HERFD-XAS) technique at the U M-4 and L-3 edges. Both U M-4 and L-3 HERFD-XAS reveal some differences between UMeC2 and UC; there are differences also between the M-4 and L-3 edge results for both types of carbide in terms of the spectral width and energy position. The observed differences are attributed to the consequences of the U 5f, 6d-4d(3d) hybridization in UMeC2. Calculations of the U M-4 HERFD-XAS spectra were also performed using the Anderson impurity model (AIM). Based on the analysis of the data, the 5f occupancy in the ground state of UC was estimated to be 3.05 electrons. This finding is also supported by the analysis of U N-4,N-5 XAS of UC and by the results of the AIM calculations of the U 4f X-ray photoelectron spectrum of UC.

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  • 22.
    Butorin, Sergei
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Shuh, D. K.
    Lawrence Berkeley Natl Lab, Chem Sci Div, MS 70A1150, One Cyclotron Rd, Berkeley, CA 94720 USA..
    Electronic structure of americium sesquioxide probed by resonant inelastic x-ray scattering2023In: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 108, no 19, article id 195152Article in journal (Refereed)
    Abstract [en]

    The Am 5d-5f resonant inelastic x-ray scattering (RIXS) data of americium sesquioxide were measured at incident photon energies throughout the Am O4,5 edges. The experiment was supported by calculations using several model approaches. While the experimental Am O4,5 x-ray absorption spectrum of Am2O3 is compared with the spectra calculated in the framework of atomic multiplet and crystal-field multiplet theories and Anderson impurity model (AIM) for the Am(III) system, the recorded Am 5d-5 f RIXS data are essentially reproduced by the crystal-field multiplet calculations. A combination of the experimental scattering geometry and theoretical analysis of the character of the electronic states probed during the RIXS process confirms that the ground state of Am2O3 is singlet P1. An appearance of the low-intense charge-transfer satellite in the Am 5d-5 f RIXS spectra at an energy loss of similar to 5.5 eV suggests weak Am 5 f-O 2p hybridization which is in agreement with AIM estimations of the 5 f occupancy from spectroscopic data in Am2O3 as being 6.05 electrons.

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  • 23.
    Butorin, Sergei
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Shuh, David K. K.
    Lawrence Berkeley Natl Lab, Chem Sci Div, MS 70A1150, One Cyclotron Rd, Berkeley, CA 94720 USA..
    Chemical bonding in americium oxides probed by X-ray spectroscopy2023In: Scientific Reports, E-ISSN 2045-2322, Vol. 13, article id 11607Article in journal (Refereed)
    Abstract [en]

    The electronic structure and the chemical state in Am binary oxides and Am-doped UO2 were studied by means of X-ray absorption spectroscopy at shallow Am core (4d and 5d) edges. In particular, the Am 5f states were probed and the nature of their bonding to the oxygen states was analyzed. The interpretation of the experimental data was supported by the Anderson impurity model (AIM) calculations which took into account the full multiplet structure due to the interaction between 5f electrons as well as the interaction with the core hole. The sensitivity of the branching ratio of the Am 4d(3/2) and 4d(5/2)X-ray absorption lines to the chemical state of Am was shown using Am binary oxides as reference systems. The observed ratio for Am-doped UO2 suggests that at least at low Am concentrations, americium is in the Am(III) state in the UO2 lattice. To confirm the validity of the applied AIM approach, the analysis of the Am 4fX-ray photoelectron spectra of AmO2 and Am2O3 was also performed which revealed a good agreement between experiment and calculations. As a whole, AmO2 can be classified as the charge-transfer compound with the 5f occupancy (n(f)) equal to 5.73 electrons, while Am2O3 is rather a Mott-Hubbard system with n(f) = 6.05.

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  • 24.
    Chareev, Dmitriy A.
    et al.
    RAS, Inst Expt Mineral IEM, Moscow 142432, Russia.;Kazan Fed Univ, Kazan 420008, Russia.;Ural Fed Univ, Ekaterinburg 620002, Russia..
    Khan, Md Ezaz Hasan
    Univ Doha Sci & Technol, Doha 24449, Qatar..
    Karmakar, Debjani
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Nekrasov, Aleksey N.
    RAS, Inst Expt Mineral IEM, Moscow 142432, Russia..
    Nickolsky, Maximilian S.
    RAS, Inst Geol Ore Deposits IGEM, Moscow 119017, Russia..
    Eriksson, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Örebro Univ, Sch Sci & Technol, SE-70182 Örebro, Sweden..
    Delin, Anna
    KTH Royal Inst Technol, Dept Appl Phys, SE-10691 Stockholm, Sweden.;KTH Royal Inst Technol, Swedish Esci Res Ctr, SE-10044 Stockholm, Sweden..
    Vasiliev, Alexander N.
    Lomonosov Moscow State Univ, Moscow 119991, Russia. Natl Univ Sci & Technol MISiS, Moscow 119049, Russia..
    Abdel-Hafiez, Mahmoud
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials. Univ Doha Sci & Technol, Doha 24449, Qatar..
    Stable Sulfuric Vapor Transport and Liquid Sulfur Growth on Transition Metal Dichalcogenides2023In: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505, Vol. 23, no 4, p. 2287-2294Article in journal (Refereed)
    Abstract [en]

    Transition metal dichalcogenides (TMDs) are an emergent class of low-dimensional materials with growing applications in the field of nanoelectronics. However, efficient methods for synthesizing large monocrystals of these systems are still lacking. Here, we describe an efficient synthetic route for a large number of TMDs that were obtained in quartz glass ampoules by sulfuric vapor transport and liquid sulfur. Unlike the sublimation technique, the metal enters the gas phase in the form of molecules, hence containing a greater amount of sulfur than the growing crystal. We have investigated the physical properties for a selection of these crystals and compared them to state-of-the-art findings reported in the literature. The acquired electronic properties features demonstrate the overall high quality of single crystals grown in this work as exemplified by CoS2, ReS2, NbS2, and TaS2. This new approach to synthesize high-quality TMD single crystals can alleviate many material quality concerns and is suitable for emerging electronic devices.

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  • 25.
    Chen, Heyin
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Ericson, Tove
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Temperton, Robert H.
    MAX IV Laboratory, Lund University, Box 118, 221 00 Lund, Sweden.
    Källquist, Ida
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Liu, Haidong
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Eads, Calley N.
    MAX IV Laboratory, Lund University, Box 118, 221 00 Lund, Sweden.
    Mikheenkova, Anastasiia
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Andersson, Margit
    MAX IV Laboratory, Lund University, Box 118, 221 00 Lund, Sweden.
    Kokkonen, Esko
    MAX IV Laboratory, Lund University, Box 118, 221 00 Lund, Sweden.
    Brant, William R.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Hahlin, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Investigating Surface Reactivity of a Ni-Rich Cathode Material toward CO2, H2O, and O2 Using Ambient Pressure X-ray Photoelectron Spectroscopy2023In: ACS Applied Energy Materials, E-ISSN 2574-0962, Vol. 6, no 22, p. 11458-11467Article in journal (Refereed)
    Abstract [en]

    Layered Ni-rich transition metal oxide materials are considered the most promising cathodes for use in commercial Li-ion batteries. Due to their instability in air, an impurity layer forms during storage under ambient conditions, and this layer increases electrochemical polarization during charging and discharging, which ultimately leads to a lower cycling capacity. In this work, we found that storage of the LiNi0.8Mn0.1Co0.1O2 (NMC 811) material in ultrahigh vacuum (UHV) can restore the surface by reducing the amount of native carbonate species in the impurity layer. In this work, in situ soft X-ray ambient pressure photoelectron spectroscopy is used to directly follow the interaction between common gases found in air and the NMC 811 surface. During gas exposure of the NMC 811 surface to pure CO2, O2, and a mixture of both pure gases, surface-adsorbed CO2 or/and O2 were detected; however, permanent changes could not be identified under UHV after the gas exposure. In contrast, a permanent increase in metal hydroxide species was observed on the sample surface following H2O vapor exposure, and an increased intensity in the carboxylate peak was observed after exposure to a mixture of CO2/O2/H2O. Thus, the irreversible degradation reaction with CO2 is triggered in the presence of H2O (on relevant time scales defined by the experiment). Additional measurements revealed that X-ray irradiation induces the formation of metal carbonate species on the NMC 811 surface under CO2 and H2O vapor pressure.

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  • 26.
    Cho, Chang-woo
    et al.
    Hong Kong Univ Sci & Technol, Dept Phys, Kowloon, Clear Water Bay, Hong Kong, Peoples R China..
    Ng, Cheuk Yin
    Hong Kong Univ Sci & Technol, Dept Phys, Kowloon, Clear Water Bay, Hong Kong, Peoples R China..
    Wong, Chi Ho
    Hong Kong Univ Sci & Technol, Dept Ind & Syst Engn, Kowloon, Hung Hom, 11 Yuk Choi Rd, Hong Kong, Peoples R China..
    Abdel-Hafiez, Mahmoud
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials. Harvard Univ, Lyman Lab Phys, Cambridge, MA 02138 USA..
    Vasiliev, Alexander N.
    Lomonosov Moscow State Univ, Dept Low Temp Phys & Superconduct, Moscow 119991, Russia.;Natl Univ Sci & Technol MISiS, Quantum Funct Mat Lab, Moscow 119049, Russia.;Ural Fed Univ, Ekaterinburg 620002, Russia..
    Chareev, Dmitriy A.
    Natl Univ Sci & Technol MISiS, Quantum Funct Mat Lab, Moscow 119049, Russia.;Ural Fed Univ, Ekaterinburg 620002, Russia.;RAS, Inst Expt Mineral, Chernogolovka 142432, Moscow Region, Russia..
    Lebed, A. G.
    Univ Arizona, Dept Phys, 1118 E 4th St, Tucson, AZ 85721 USA.;RAS, Landau Inst Theoret Phys, 2 Kosygina St, Moscow 117334, Russia..
    Lortz, Rolf
    Hong Kong Univ Sci & Technol, Dept Phys, Kowloon, Clear Water Bay, Hong Kong, Peoples R China..
    Competition between orbital effects, Pauli limiting, and Fulde-Ferrell-Larkin-Ovchinnikov states in 2D transition metal dichalcogenide superconductors2022In: New Journal of Physics, E-ISSN 1367-2630, Vol. 24, no 8, article id 083001Article in journal (Refereed)
    Abstract [en]

    We compare the upper critical field of bulk single-crystalline samples of the two intrinsic transition metal dichalcogenide superconductors, 2H-NbSe2 and 2H-NbS2, in high magnetic fields where their layer structure is aligned strictly parallel and perpendicular to the field, using magnetic torque experiments and a high-precision piezo-rotary positioner. While both superconductors show that orbital effects still have a significant impact when the layer structure is aligned parallel to the field, the upper critical field of NbS2 rises above the Pauli limiting field and forms a Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state, while orbital effects suppress superconductivity in NbSe2 just below the Pauli limit, which excludes the formation of the FFLO state. From the out-of-plane anisotropies, the coherence length perpendicular to the layers of 31 angstrom in NbSe2 is much larger than the interlayer distance, leading to a significant orbital effect suppressing superconductivity before the Pauli limit is reached, in contrast to the more 2D NbS2.

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  • 27.
    Cohen-Azarzar, Dana
    et al.
    Technion Israel Inst Technol, Andrew & Erna Viterbi Dept Elect & Comp Engn, IL-3200003 Haifa, Israel..
    Baskin, Maria
    Technion Israel Inst Technol, Andrew & Erna Viterbi Dept Elect & Comp Engn, IL-3200003 Haifa, Israel..
    Lindblad, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Trier, Felix
    Tech Univ Denmark, Dept Energy Convers & Storage, DK-2800 Lyngby, Denmark..
    Kornblum, Lior
    Technion Israel Inst Technol, Andrew & Erna Viterbi Dept Elect & Comp Engn, IL-3200003 Haifa, Israel..
    Scalable and highly tunable conductive oxide interfaces2023In: APL Materials, E-ISSN 2166-532X, Vol. 11, no 11, article id 111118Article in journal (Refereed)
    Abstract [en]

    Conducting oxide interfaces have attracted considerable attention, motivated by both fundamental science and potential for oxide electronic devices. An important gap for maturing such device technology is scalability and routes to control the electronic properties, which can narrow the device engineering space. Here, we demonstrate and explain the mechanisms of highly tunable conductive oxide interfaces. We synthesized amorphous-crystalline Al2O3/SrTiO3 interfaces using the scalable and industry-compatible atomic layer deposition (ALD) technique. An NH3 plasma pretreatment is employed in the ALD chamber, and its duration is used as a tuning parameter for the electrical properties, where a span of three orders of magnitude in the sheet resistance is observed at room temperature. For the most conductive sample, our results are comparable to the highest carrier density values reported for all-crystalline oxide interfaces prepared with state-of-the-art epitaxial growth techniques, such as pulsed laser deposition. We pinpoint the origin of conductivity to oxygen vacancies caused by the SrTiO3 reduction by the NH3 plasma pretreatment. These results present a simple, scalable, and industry-compatible route for realizing conductive oxide interfaces, with a broad parameter space, offering a versatile and flexible toolkit for oxide device engineering.

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  • 28.
    Dey, Ananta
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Silveira, Vitor R.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Bericat Vadell, Robert
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Lindblad, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Lindblad, Rebecka
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Shtender, Vitalii
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Görlin, Mikaela
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Sá, Jacinto
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry. Polish Acad Sci, Inst Phys Chem, Marcina Kasprzaka 44-52, PL-01224 Warsaw, Poland.
    Exploiting hot electrons from a plasmon nanohybrid system for the photoelectroreduction of CO22024In: Communications Chemistry, E-ISSN 2399-3669, Vol. 7, no 1, article id 59Article in journal (Refereed)
    Abstract [en]

    Plasmonic materials convert light into hot carriers and heat to mediate catalytic transformation. The participation of hot carriers (photocatalysis) remains a subject of vigorous debate, often argued on the basis that carriers have ultrashort lifetime incompatible with drive photochemical processes. This study utilises plasmon hot electrons directly in the photoelectrocatalytic reduction of CO2 to CO via a Ppasmonic nanohybrid. Through the deliberate construction of a plasmonic nanohybrid system comprising NiO/Au/ReI(phen-NH2)(CO)3Cl (phen-NH2 = 1,10-Phenanthrolin-5-amine) that is unstable above 580 K; it was possible to demonstrate hot electrons are the main culprit in CO2 reduction. The engagement of hot electrons in the catalytic process is derived from many approaches that cover the processes in real-time, from ultrafast charge generation and separation to catalysis occurring on the minute scale. Unbiased in situ FTIR spectroscopy confirmed the stepwise reduction of the catalytic system. This, coupled with the low thermal stability of the ReI(phen-NH2)(CO)3Cl complex, explicitly establishes plasmonic hot carriers as the primary contributors to the process. Therefore, mediating catalytic reactions by plasmon hot carriers is feasible and holds promise for further exploration. Plasmonic nanohybrid systems can leverage plasmon’s unique photophysics and capabilities because they expedite the carrier’s lifetime.

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  • 29.
    Dong, Yu
    et al.
    Nanjing Univ, Sch Elect Sci & Engn, Nanjing 210093, Peoples R China.;Nanjing Univ, Sch Phys, Nanjing 210093, Peoples R China.;Nanjing Univ, Natl Lab Solid State Microstruct, Nanjing 210093, Peoples R China.;Nanjing Univ, Collaborat Innovat Ctr Adv Microstruct, Nanjing 210093, Peoples R China..
    Lv, Yangyang
    Nanjing Univ, Sch Elect Sci & Engn, Nanjing 210093, Peoples R China.;Nanjing Univ, Sch Phys, Nanjing 210093, Peoples R China.;Nanjing Univ, Natl Lab Solid State Microstruct, Nanjing 210093, Peoples R China.;Nanjing Univ, Collaborat Innovat Ctr Adv Microstruct, Nanjing 210093, Peoples R China..
    Xu, Zuyu
    Nanjing Univ, Sch Elect Sci & Engn, Nanjing 210093, Peoples R China.;Nanjing Univ, Sch Phys, Nanjing 210093, Peoples R China.;Nanjing Univ, Natl Lab Solid State Microstruct, Nanjing 210093, Peoples R China.;Nanjing Univ, Collaborat Innovat Ctr Adv Microstruct, Nanjing 210093, Peoples R China..
    Abdel-Hafiez, Mahmoud
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials. Natl Univ Sci & Technol MISiS, Moscow 119049, Russia.
    Vasiliev, A. N.
    Natl Univ Sci & Technol MISiS, Moscow 119049, Russia.;Moscow MV Lomonosov State Univ, Moscow 119991, Russia..
    Zhu, Haipeng
    Huazhong Univ Sci & Technol, Wuhan Natl High Magnet Field Ctr, Wuhan 430074, Peoples R China.;Huazhong Univ Sci & Technol, Sch Phys, Wuhan 430074, Peoples R China..
    Wang, Junfeng
    Huazhong Univ Sci & Technol, Wuhan Natl High Magnet Field Ctr, Wuhan 430074, Peoples R China.;Huazhong Univ Sci & Technol, Sch Phys, Wuhan 430074, Peoples R China..
    Li, Liang
    Huazhong Univ Sci & Technol, Wuhan Natl High Magnet Field Ctr, Wuhan 430074, Peoples R China.;Huazhong Univ Sci & Technol, Sch Phys, Wuhan 430074, Peoples R China..
    Tian, Wanghao
    Nanjing Univ, Sch Elect Sci & Engn, Nanjing 210093, Peoples R China.;Nanjing Univ, Sch Phys, Nanjing 210093, Peoples R China.;Nanjing Univ, Natl Lab Solid State Microstruct, Nanjing 210093, Peoples R China.;Nanjing Univ, Collaborat Innovat Ctr Adv Microstruct, Nanjing 210093, Peoples R China..
    Chen, Wei
    Nanjing Univ, Sch Elect Sci & Engn, Nanjing 210093, Peoples R China.;Nanjing Univ, Sch Phys, Nanjing 210093, Peoples R China.;Nanjing Univ, Natl Lab Solid State Microstruct, Nanjing 210093, Peoples R China.;Nanjing Univ, Collaborat Innovat Ctr Adv Microstruct, Nanjing 210093, Peoples R China..
    Bao, Song
    Nanjing Univ, Sch Elect Sci & Engn, Nanjing 210093, Peoples R China.;Nanjing Univ, Sch Phys, Nanjing 210093, Peoples R China.;Nanjing Univ, Natl Lab Solid State Microstruct, Nanjing 210093, Peoples R China.;Nanjing Univ, Collaborat Innovat Ctr Adv Microstruct, Nanjing 210093, Peoples R China..
    Wang, Jinghui
    Nanjing Univ, Sch Elect Sci & Engn, Nanjing 210093, Peoples R China.;Nanjing Univ, Sch Phys, Nanjing 210093, Peoples R China.;Nanjing Univ, Natl Lab Solid State Microstruct, Nanjing 210093, Peoples R China.;Nanjing Univ, Collaborat Innovat Ctr Adv Microstruct, Nanjing 210093, Peoples R China..
    Wu, Yueshen
    ShanghaiTech Univ, ShanghaiTech Lab Topol Phys, Shanghai 201210, Peoples R China.;ShanghaiTech Univ, Sch Phys Sci & Technol, Shanghai 201210, Peoples R China..
    Huang, Yulong
    Chinese Acad Sci, Beijing Natl Lab Condensed Matter Phys, Beijing 100190, Peoples R China.;Chinese Acad Sci, Inst Phys, Beijing 100190, Peoples R China..
    Li, Shiliang
    Chinese Acad Sci, Beijing Natl Lab Condensed Matter Phys, Beijing 100190, Peoples R China.;Chinese Acad Sci, Inst Phys, Beijing 100190, Peoples R China..
    Yuan, Jie
    Chinese Acad Sci, Beijing Natl Lab Condensed Matter Phys, Beijing 100190, Peoples R China.;Chinese Acad Sci, Inst Phys, Beijing 100190, Peoples R China..
    Jin, Kui
    Chinese Acad Sci, Beijing Natl Lab Condensed Matter Phys, Beijing 100190, Peoples R China.;Chinese Acad Sci, Inst Phys, Beijing 100190, Peoples R China..
    Zhang, Labao
    Nanjing Univ, Sch Elect Sci & Engn, Nanjing 210093, Peoples R China.;Nanjing Univ, Sch Phys, Nanjing 210093, Peoples R China..
    Wang, Huabing
    Nanjing Univ, Sch Elect Sci & Engn, Nanjing 210093, Peoples R China.;Nanjing Univ, Sch Phys, Nanjing 210093, Peoples R China..
    Yu, Shun-Li
    Nanjing Univ, Sch Elect Sci & Engn, Nanjing 210093, Peoples R China.;Nanjing Univ, Sch Phys, Nanjing 210093, Peoples R China.;Nanjing Univ, Natl Lab Solid State Microstruct, Nanjing 210093, Peoples R China.;Nanjing Univ, Collaborat Innovat Ctr Adv Microstruct, Nanjing 210093, Peoples R China..
    Wen, Jinsheng
    Nanjing Univ, Sch Elect Sci & Engn, Nanjing 210093, Peoples R China.;Nanjing Univ, Sch Phys, Nanjing 210093, Peoples R China.;Nanjing Univ, Natl Lab Solid State Microstruct, Nanjing 210093, Peoples R China.;Nanjing Univ, Collaborat Innovat Ctr Adv Microstruct, Nanjing 210093, Peoples R China..
    Li, Jian-Xin
    Nanjing Univ, Sch Elect Sci & Engn, Nanjing 210093, Peoples R China.;Nanjing Univ, Sch Phys, Nanjing 210093, Peoples R China.;Nanjing Univ, Natl Lab Solid State Microstruct, Nanjing 210093, Peoples R China.;Nanjing Univ, Collaborat Innovat Ctr Adv Microstruct, Nanjing 210093, Peoples R China..
    Li, Jun
    Nanjing Univ, Sch Elect Sci & Engn, Nanjing 210093, Peoples R China.;Nanjing Univ, Sch Phys, Nanjing 210093, Peoples R China.;ShanghaiTech Univ, ShanghaiTech Lab Topol Phys, Shanghai 201210, Peoples R China.;ShanghaiTech Univ, Sch Phys Sci & Technol, Shanghai 201210, Peoples R China..
    Wu, Peiheng
    Nanjing Univ, Sch Elect Sci & Engn, Nanjing 210093, Peoples R China.;Nanjing Univ, Sch Phys, Nanjing 210093, Peoples R China.;Univ Sci & Technol China, Synerget Innovat Ctr Quantum Informat & Quantum P, Hefei 230026, Peoples R China..
    Observation of a Ubiquitous (π, π)-Type Nematic Superconducting Order in the Whole Superconducting Dome of Ultra-Thin BaFe2–xNixAs2 Single Crystals2021In: Chinese Physics Letters, ISSN 0256-307X, E-ISSN 1741-3540, Vol. 38, no 9, article id 097401Article in journal (Refereed)
    Abstract [en]

    In iron-based superconductors, the (0, pi) or (pi, 0) nematicity, which describes an electronic anisotropy with a four-fold symmetry breaking, is well established and believed to be important for understanding the superconducting mechanism. However, how exactly such a nematic order observed in the normal state can be related to the superconducting pairing is still elusive. Here, by performing angular-dependent in-plane magnetoresistivity using ultra-thin flakes in the steep superconducting transition region, we unveil a nematic superconducting order along the (pi, pi) direction in electron-doped BaFe2 - x Ni x As2 from under-doped to heavily overdoped regimes with x = 0.065-0.18. It shows superconducting gap maxima along the (pi, pi) direction rotated by 45 degrees from the nematicity along (0, pi) or (pi, 0) direction observed in the normal state. A similar (pi, pi)-type nematicity is also observed in the under-doped and optimally doped hole-type Ba1 - y K y Fe2As2, with y = 0.2-0.5. These results suggest that the (pi, pi) nematic superconducting order is a universal feature that needs to be taken into account in the superconducting pairing mechanism in iron-based superconductors.

  • 30.
    Elhanoty, Mohamed F.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Eriksson, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Örebro Univ, Sch Sci & Technol, SE-70182 Örebro, Sweden..
    Knut, Ronny
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Karis, Olof
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Grånäs, Oscar
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Different fingerprints for the OISTR mechanism in the magnetic alloys experiments2022In: ADVANCES IN ULTRAFAST CONDENSED PHASE PHYSICS III / [ed] Haacke, S Yakovlev, V, SPIE-Intl Soc Optical Eng SPIE - The International Society for Optics and Photonics, 2022, Vol. 12132, article id 121320BConference paper (Refereed)
    Abstract [en]

    The interplay between various degrees of freedom in laser induced ultrafast magnetization dynamics (LIUMD) of magnetic alloys is intricate due to the competition between different mechanisms and processes. In this work, we resolve the element specific magnetization dynamics of FePd alloy and further elucidate the dependency of the OISTR mechanism on the laser pulse parameters using ultrashort, short and relatively longer pulse duration with weak and strong fluence. Remarkably, our results illustrate potential discrepancies in experiments measuring the optical inter site spin transfer (OISTR) effect in magnetic alloys.

  • 31.
    Elsayed, Mohamed Hammad
    et al.
    Natl Tsing Hua Univ, Dept Chem Engn, Hsinchu 300044, Taiwan.;Al Azhar Univ, Fac Sci, Dept Chem, Cairo 11884, Egypt..
    Abdellah, Mohamed
    Lund Univ, Chem Phys & NanoLund, S-22100 Lund, Sweden.;South Valley Univ, Qena Fac Sci, Dept Chem, Qena 83523, Egypt..
    Hung, Yi-Hao
    Natl Tsing Hua Univ, Dept Chem Engn, Hsinchu 300044, Taiwan..
    Jayakumar, Jayachandran
    Natl Tsing Hua Univ, Dept Chem Engn, Hsinchu 300044, Taiwan..
    Ting, Li-Yu
    Natl Tsing Hua Univ, Dept Chem Engn, Hsinchu 300044, Taiwan..
    Elewa, Ahmed M.
    Natl Tsing Hua Univ, Dept Chem Engn, Hsinchu 300044, Taiwan..
    Chang, Chih-Li
    Natl Tsing Hua Univ, Dept Chem Engn, Hsinchu 300044, Taiwan..
    Lin, Wei-Cheng
    Natl Tsing Hua Univ, Dept Chem Engn, Hsinchu 300044, Taiwan..
    Wang, Kuo-Lung
    Natl Tsing Hua Univ, Dept Chem Engn, Hsinchu 300044, Taiwan..
    Abdel-Hafiez, Mahmoud
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials. Fayoum Univ, Phys Dept, Fac Sci, Al Fayyum 63514, Egypt..
    Hung, Hsiao-Wen
    Ind Technol Res Inst, Lighting Energy Saving Dept, Intelligent Energy Saving Syst Div, Green Energy & Environm Res Labs, Hsinchu 310401, Taiwan..
    Horie, Masaki
    Natl Tsing Hua Univ, Dept Chem Engn, Hsinchu 300044, Taiwan..
    Chou, Ho-Hsiu
    Natl Tsing Hua Univ, Dept Chem Engn, Hsinchu 300044, Taiwan..
    Hydrophobic and Hydrophilic Conjugated Polymer Dots as Binary Photocatalysts for Enhanced Visible-Light-Driven Hydrogen Evolution through Forster Resonance Energy Transfer2021In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 13, no 47, p. 56554-56565Article in journal (Refereed)
    Abstract [en]

    Organic semiconducting polymers exhibited promising photocatalytic behavior for hydrogen (H-2) evolution, especially when prepared in the form of polymer dots (Pdots). However, the Pdot structures were formed using common nonconjugated amphiphilic polymers, which have a negative effect on charge transfer between photocatalysts and reactants and are unable to participate in the photocatalytic reaction. This study presents a new strategy for constructing binary Pdot photocatalysts by replacing the nonconjugated amphiphilic polymer typically employed in the preparation of polymer nanoparticles (Pdots) with a low-molecular-weight conjugated polyelectrolyte. The as-prepared polyelectrolyte/hydrophobic polymer-based binary Pdots truly enhance the electron transfer between the Pt cocatalyst and the polymer photocatalyst with good water dispersibility. Moreover, unlike the nonconjugated amphiphilic polymer, the photophysics and mechanism of this photocatalytic system through time-correlated single-photon counting (TCSPC) and transient absorption (TA) measurements confirmed the Forster resonance energy transfer (FRET) between the polyelectrolyte as a donor and the hydrophobic polymer as an acceptor. As a result, the designated binary Pdot photocatalysts significantly enhanced the hydrogen evolution rate (HER) of 43 900 mu mol g(-1) h(-1) (63.5 mu mol h(-1), at 420 nm) for PTTPA/PFTBTA Pdots under visible-light irradiation.

  • 32.
    Erbing, Axel
    et al.
    Stockholm Univ, AlbaNova Univ Ctr, Dept Phys, SE-10691 Stockholm, Sweden..
    Philippe, Bertrand
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Park, Byung-wook
    Ulsan Natl Inst Sci & Technol, Dept Energy & Chem Engn, 50 UNIST Gil, Ulsan 44919, South Korea..
    Cappel, Ute B.
    KTH Royal Inst Technol, Div Appl Phys Chem, Dept Chem, SE-10044 Stockholm, Sweden..
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Odelius, Michael
    Stockholm Univ, AlbaNova Univ Ctr, Dept Phys, SE-10691 Stockholm, Sweden..
    Spatial microheterogeneity in the valence band of mixed halide hybrid perovskite materials2022In: Chemical Science, ISSN 2041-6520, E-ISSN 2041-6539, Vol. 13, no 32, p. 9285-9294Article in journal (Refereed)
    Abstract [en]

    The valence band of lead halide hybrid perovskites with a mixed I/Br composition is investigated using electronic structure calculations and complementarily probed with hard X-ray photoelectron spectroscopy. In the latter, we used high photon energies giving element sensitivity to the heavy lead and halide ions and we observe distinct trends in the valence band as a function of the I : Br ratio. Through electronic structure calculations, we show that the spectral trends with overall composition can be understood in terms of variations in the local environment of neighboring halide ions. From the computational model supported by the experimental evidence, a picture of the microheterogeneity in the valence band maximum emerges. The microheterogeneity in the valence band suggests that additional charge transport mechanisms might be active in lead mixed halide hybrid perovskites, which could be described in terms of percolation pathways.

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  • 33.
    Franchi, Daniele
    et al.
    Inst Chem Organometall Cpds CNR ICCOM, I-50019 Sesto Fiorentino, Italy.;KTH Royal Inst Technol, Ctr Mol Devices, Dept Chem, Div Organ Chem, SE-10044 Stockholm, Sweden..
    Leandri, Valentina
    KTH Royal Inst Technol, Ctr Mol Devices, Dept Chem, Div Appl Phys Chem, SE-10044 Stockholm, Sweden..
    Pizzichetti, Angela Raffaella Pia
    KTH Royal Inst Technol, Ctr Mol Devices, Dept Chem, Div Appl Phys Chem, SE-10044 Stockholm, Sweden..
    Xu, Bo
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
    Hao, Yan
    KTH Royal Inst Technol, Ctr Mol Devices, Dept Chem, Div Appl Phys Chem, SE-10044 Stockholm, Sweden..
    Zhang, Wei
    KTH Royal Inst Technol, Ctr Mol Devices, Dept Chem, Div Appl Phys Chem, SE-10044 Stockholm, Sweden..
    Sloboda, Tamara
    KTH Royal Inst Technol, Ctr Mol Devices, Dept Chem, Div Appl Phys Chem, SE-10044 Stockholm, Sweden..
    Svanström, Sebastian
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Cappel, Ute B.
    KTH Royal Inst Technol, Ctr Mol Devices, Dept Chem, Div Appl Phys Chem, SE-10044 Stockholm, Sweden..
    Kloo, Lars
    KTH Royal Inst Technol, Ctr Mol Devices, Dept Chem, Div Appl Phys Chem, SE-10044 Stockholm, Sweden..
    Sun, Licheng
    KTH Royal Inst Technol, Ctr Mol Devices, Dept Chem, Div Organ Chem, SE-10044 Stockholm, Sweden.;Westlake Univ, Ctr Artificial Photosynth Solar Fuels, Sch Sci, Hangzhou 310024, Peoples R China..
    Gardner, James M.
    KTH Royal Inst Technol, Ctr Mol Devices, Dept Chem, Div Appl Phys Chem, SE-10044 Stockholm, Sweden..
    Effect of the Ancillary Ligand on the Performance of Heteroleptic Cu(I) Diimine Complexes as Dyes in Dye-Sensitized Solar Cells2022In: ACS Applied Energy Materials, E-ISSN 2574-0962, Vol. 5, no 2, p. 1460-1470Article in journal (Refereed)
    Abstract [en]

    A series of heteroleptic Cu(I) diimine complexes with different ancillary ligands and 6,6'-dimethyl-2,2'-bipyridine-4,4'-dibenzoic acid (dbda) as the anchoring ligand were selfassembled on TiO2 surfaces and used as dyes for dye-sensitized solar cells (DSSCs). The binding to the TiO2 surface was studied by hard X-ray photoelectron spectroscopy for a brominecontaining complex, confirming the complex formation. The performance of all complexes was assessed and rationalized on the basis of their respective ancillary ligand. The DSSC photocurrent-voltage characteristics, incident photon-to-current conversion efficiency (IPCE) spectra, and calculated lowest unoccupied molecular orbital (LUMO) distributions collectively show a push-pull structural dye design, in which the ancillary ligand exhibits an electron-donating effect that can lead to improved solar cell performance. By analyzing the optical properties of the dyes and their solar cell performance, we can conclude that the presence of ancillary ligands with bulky substituents protects the Cu(I) metal center from solvent coordination constituting a critical factor in the design of efficient Cu(I)-based dyes. Moreover, we have identified some components in the I-/I-3(-)-based electrolyte that causes dissociation of the ancillary ligand, i.e., TiO2 photoelectrode bleaching. Finally, the detailed studies on one of the dyes revealed an electrolyte-dye interaction, leading to a dramatic change of the dye properties when adsorbed on the TiO2 surface.

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  • 34.
    Fritze, Stefan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Hahn, R.
    Institute of Materials Science and Technology, TU Wien, Vienna, Austria.
    Aboulfadl, H.
    Department of Physics, Chalmers University of Technology, Göteborg, Sweden.
    Johansson, Fredrik O.L.
    Division of Applied Physical Chemistry, Department of Chemistry, KTH – Royal Institute of Technology, SE-100 44 Stockholm, Sweden; Institute Methods and Instrumentation for Synchrotron Radiation Research PS-ISRR, Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Straße 15, 12489 Berlin, Germany; Institut für Physik und Astronomie, Universität Potsdam, Karl-Liebknecht-Strasse 24-25, 14476 Potsdam, Germany.
    Lindblad, Rebecka
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
    Böör, Katalin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Lindblad, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Berggren, Elin
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Kühn, D.
    Institute Methods and Instrumentation for Synchrotron Radiation Research PS-ISRR, Helmholtz-Zentrum Berlin für Materialien und Energie, Berlin, Germany.
    Leitner, T.
    Institute Methods and Instrumentation for Synchrotron Radiation Research PS-ISRR, Helmholtz-Zentrum Berlin für Materialien und Energie, Berlin, Germany.
    Osinger, Barbara
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Lewin, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Jansson, Ulf
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Mayrhofer, P.H.
    Institute of Materials Science and Technology, TU Wien, Vienna, Austria.
    Thuvander, M.
    Department of Physics, Chalmers University of Technology, Göteborg, Sweden.
    Elemental distribution and fracture properties of magnetron sputtered carbon supersaturated tungsten films2024In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 477, article id 130326Article in journal (Refereed)
    Abstract [en]

    The combination of strength and toughness is a major driving force for alloy design of protective coatings, and nanocrystalline tungsten (W)-alloys have shown to be promising candidates for combining strength and toughness. Here we investigate the elemental distribution and the fracture toughness of carbon (C) alloyed W thin films prepared by non-reactive magnetron sputtering. W:C films with up to ~4 at.% C crystallize in a body-centered-cubic structure with a strong 〈hh0〉texture, and no additional carbide phases are observed in the diffraction pattern. Atom probe tomography and X-ray photoelectron spectroscopy confirmed the formation of such a supersaturated solid solution. The pure W film has a hardness ~13 GPa and the W:C films exhibit a peak hardness of ~24 GPa. In-situ micromechanical cantilever bending tests show that the fracture toughness decreases from ~4.5 MPa·m1/2 for the W film to ~3.1 MPa·m1/2 for W:C films. The results show that C can significantly enhance the hardness of W thin films while retaining a high fracture toughness.

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  • 35.
    Fytory, Mostafa
    et al.
    Zewail City Sci & Technol, Ctr Mat Sci CMS, Nanomed Labs, Giza 12578, Egypt.;Beni Suef Univ, Fac Postgrad Studies Adv Sci PSAS, Mat Sci & Nanotechnol Dept, Bani Suwayf 62511, Egypt..
    Mansour, Amira
    Zewail City Sci & Technol, Ctr Mat Sci CMS, Nanomed Labs, Giza 12578, Egypt..
    El Rouby, Waleed M. A.
    Beni Suef Univ, Fac Postgrad Studies Adv Sci PSAS, Mat Sci & Nanotechnol Dept, Bani Suwayf 62511, Egypt..
    Farghali, Ahmed A.
    Beni Suef Univ, Fac Postgrad Studies Adv Sci PSAS, Mat Sci & Nanotechnol Dept, Bani Suwayf 62511, Egypt..
    Zhang, Xiaorong
    Univ Potsdam, Inst Biochem & Biol, Mol Bioanalyt & Bioelect Grp, D-14476 Potsdam, Germany..
    Bier, Frank
    Univ Potsdam, Inst Biochem & Biol, Mol Bioanalyt & Bioelect Grp, D-14476 Potsdam, Germany..
    Abdel-Hafiez, Mahmoud
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    El-Sherbiny, Ibrahim M.
    Zewail City Sci & Technol, Ctr Mat Sci CMS, Nanomed Labs, Giza 12578, Egypt..
    Core-Shell Nanostructured Drug Delivery Platform Based on Biocompatible Metal-Organic Framework-Ligated Polyethyleneimine for Targeted Hepatocellular Carcinoma Therapy2023In: ACS Omega, E-ISSN 2470-1343, Vol. 8, no 23, p. 20779-20791Article in journal (Refereed)
    Abstract [en]

    Multifunctional nanosized metal-organic frameworks(NMOFs)have advanced rapidly over the past decade to develop drug deliverysystems (DDSs). These material systems still lack precise and selectivecellular targeting, as well as the fast release of the quantity ofdrugs that are simply adsorbed within and on the external surfaceof nanocarriers, which hinders their application in the drug delivery.Herein, we designed a biocompatible Zr-based NMOF with an engineeredcore and the hepatic tumor-targeting ligand, glycyrrhetinic acid graftedto polyethyleneimine (PEI) as the shell. The improved core-shellserves as a superior nanoplatform for efficient controlled and activedelivery of the anticancer drug doxorubicin (DOX) against hepaticcancer cells (HepG2 cells). In addition to their high loading capacityof 23%, the developed nanostructure DOX@NMOF-PEI-GA showed an acidicpH-stimulated response and extended the drug release time to 9 daysas well as enhanced the selectivity toward the tumor cells. Interestingly,the DOX-free nanostructures showed a minimal toxic effect on bothnormal human skin fibroblast (HSF) and hepatic cancer cell line (HepG2),but the DOX-loaded nanostructures exhibited a superior killing effecttoward the hepatic tumor, thus opening the way for the active drugdelivery and achieving efficient cancer therapy applications.

  • 36.
    Ganegoda, Hasitha
    et al.
    IIT, Dept Phys, Chicago, IL 60616 USA.;IIT, Ctr Synchrotron Radiat Res & Instrumentat, Chicago, IL 60616 USA..
    Mukherjee, Soham
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Ma, Beihai
    Argonne Natl Lab, Appl Mat Div, 9700 S Cass Ave, Argonne, IL 60439 USA..
    Olive, Daniel T.
    IIT, Dept Phys, Chicago, IL 60616 USA.;IIT, Ctr Synchrotron Radiat Res & Instrumentat, Chicago, IL 60616 USA..
    McNeely, James H.
    IIT, Dept Chem, Chicago, IL 60616 USA..
    Kaduk, James A.
    IIT, Dept Chem, Chicago, IL 60616 USA.;Poly Crystallog Inc, Naperville, IL 60540 USA..
    Terry, Jeff
    IIT, Dept Phys, Chicago, IL 60616 USA.;IIT, Ctr Synchrotron Radiat Res & Instrumentat, Chicago, IL 60616 USA..
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Segre, Carlo U.
    IIT, Dept Phys, Chicago, IL 60616 USA.;IIT, Ctr Synchrotron Radiat Res & Instrumentat, Chicago, IL 60616 USA..
    Role of Fe Doping on Local Structure and Electrical and Magnetic Properties of PbTiO32021In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 125, no 22, p. 12342-12354Article in journal (Refereed)
    Abstract [en]

    The local structure and multiferroic properties of iron-doped lead titanate (PbTi1-xFexO3-delta) samples was investigated over the entire composition range (x = 0-1). Inherent polarization in PbTiO3 decreases due to Fe3+ incorporation up to the solubility limit (x similar to 0.3), although homogeneous doping persists only up to x = 0.1. Ti prefers highly distorted oxygen octahedra for any x value, while Fe prefers more symmetric O-deficient polyhedra (Fe-O-n). The charge compensating oxygen vacancies induce local tilting of the Fe-O-n polyhedra beyond a critical x value (x >= 0.2), promoting magnetic interaction between two adjacent Fe atoms. The strain induced by local heterogeneity could act as a coupling force between magnetic and ferroelectric properties. Fe-rich clusters evolve into ferromagnetic PbFe12O19 with increased Fe doping. PbTi1-xFexO3-delta ( x >= 0.3) samples therefore have separate origins for the ferroelectric (PbTi1-xFexO3-delta) and magnetic (PbFe12O19) phases.

  • 37.
    Garcia-Fernandez, Alberto
    et al.
    KTH Royal Inst Technol, Dept Chem, Div Appl Phys Chem, S-10044 Stockholm, Sweden..
    Kammlander, Birgit
    KTH Royal Inst Technol, Dept Chem, Div Appl Phys Chem, S-10044 Stockholm, Sweden..
    Riva, Stefania
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Kuehn, Danilo
    Helmholtz Zentrum Berlin Mat & Energie, Inst Methods & Instrumentat Synchrotron Radiat Re, D-12489 Berlin, Germany..
    Svanström, Sebastian
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy. Uppsala Univ, Dept Phys & Astron, Div Xray Photon Sci, S-75120 Uppsala, Sweden..
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Cappel, Ute B.
    Interface Energy Alignment between Lead Halide Perovskite Single Crystals and TIPS-Pentacene2023In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 62, no 38, p. 15412-15420Article in journal (Refereed)
    Abstract [en]

    At present, there is a huge development in optoelectronic applications using lead halide perovskites. Considering that device performance is largely governed by the transport of charges across interfaces and, therefore, the interfacial electronic structure, fundamental investigations of perovskite interfaces are highly necessary. In this study, we use high-resolution soft X-ray photoelectron spectroscopy based on synchrotron radiation to explore the interfacial energetics for the molecular layer of TIPS-pentacene and lead halide perovskite single crystals. We perform ultrahigh vacuum studies on multiple thicknesses of an in situ formed interface of TIPS-pentacene with four different in situ cleaved perovskite single crystals (MAPbI(3), MAPbBr(3), FAPbBr(3), and Cs(x)FA(1-x)PbBr(y)I(3-y)). Our findings reveal a substantial shift of the TIPS-pentacene energy levels toward higher binding energies with increasing thickness, while the perovskite energy levels remain largely unaffected regardless of their composition. These shifts can be interpreted as band bending in the TIPS-pentacene, and such effects should be considered when assessing the energy alignment at perovskite/organic transport material interfaces. Furthermore, we were able to follow a reorganization on the MAPbI3 surface with the transformation of the surface C 1s into bulk C 1s.

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  • 38.
    Garcia-Fernandez, Alberto
    et al.
    KTH Royal Inst Technol, Dept Chem, Div Appl Phys Chem, S-10044 Stockholm, Sweden..
    Kammlander, Birgit
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy. KTH Royal Inst Technol, Dept Chem, Div Appl Phys Chem, S-10044 Stockholm, Sweden..
    Riva, Stefania
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Cappel, Ute B.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials. KTH Royal Inst Technol, Dept Chem, Div Appl Phys Chem, S-10044 Stockholm, Sweden.;Uppsala Univ, Dept Phys & Astron, Wallenberg Initiat Mat Sci Sustainabil, S-75120 Uppsala, Sweden..
    Composition dependence of X-ray stability and degradation mechanisms at lead halide perovskite single crystal surfaces2024In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 26, no 2, p. 1000-1010Article in journal (Refereed)
    Abstract [en]

    The multiple applications of lead halide perovskite materials and the extensive use of X-ray based techniques to characterize them highlight a need to understand their stability under X-ray irradiation. Here, we present a study where the X-ray stability of five different lead halide perovskite compositions (MAPbI3, MAPbCl3, MAPbBr3, FAPbBr3, CsPbBr3) was investigated using photoelectron spectroscopy. To exclude effects of thin film formation on the observed degradation behaviors, we studied clean surfaces of single crystals. Different X-ray resistance and degradation mechanisms were observed depending on the crystal composition. Overall, perovskites based on the MA+ cation were found to be less stable than those based on FA+ or Cs+. Metallic lead formed most easily in the chloride perovskite, followed by bromide, and only very little metallic lead formation was observed for MAPbI3. MAPbI3 showed one main degradation process, which was the radiolysis of MAI. Multiple simultaneous degradation processes were identified for the bromide compositions. These processes include ion migration towards the perovskite surface and the formation of volatile and solid products in addition to metallic lead. Lastly, CsBr formed as a solid degradation product on the surface of CsPbBr3.

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  • 39.
    Garcia-Fernandez, Alberto
    et al.
    KTH Royal Inst Technol, Dept Chem, Div Appl Phys Chem, SE-10044 Stockholm, Sweden..
    Svanström, Sebastian
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Sterling, Cody M.
    Stockholm Univ, AlbaNova Univ Ctr, Dept Phys, S-10691 Stockholm, Sweden..
    Gangan, Abhijeet
    Stockholm Univ, AlbaNova Univ Ctr, Dept Phys, S-10691 Stockholm, Sweden..
    Erbing, Axel
    Stockholm Univ, AlbaNova Univ Ctr, Dept Phys, S-10691 Stockholm, Sweden..
    Kamal, Chinnathambi
    Stockholm Univ, AlbaNova Univ Ctr, Dept Phys, S-10691 Stockholm, Sweden.;Raja Ramanna Ctr Adv Technol, Theory & Simulat Lab, HRDS, Indore 452013, Madhya Pradesh, India.;Homi Bhabha Natl Inst, Training Sch Complex, Mumbai 400094, Maharashtra, India..
    Sloboda, Tamara
    KTH Royal Inst Technol, Dept Chem, Div Appl Phys Chem, SE-10044 Stockholm, Sweden..
    Kammlander, Birgit
    KTH Royal Inst Technol, Dept Chem, Div Appl Phys Chem, SE-10044 Stockholm, Sweden..
    Man, Gabriel
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Odelius, Michael
    Stockholm Univ, AlbaNova Univ Ctr, Dept Phys, S-10691 Stockholm, Sweden..
    Cappel, Ute B.
    KTH Royal Inst Technol, Dept Chem, Div Appl Phys Chem, SE-10044 Stockholm, Sweden..
    Experimental and Theoretical Core Level and Valence Band Analysis of Clean Perovskite Single Crystal Surfaces2022In: Small : nano micro, Vol. 18, no 13, article id 2106450Article in journal (Refereed)
    Abstract [en]

    A detailed understanding of the surface and interface properties of lead halide perovskites is of interest for several applications, in which these materials may be used. To develop this understanding, the study of clean crystalline surfaces can be an important stepping stone. In this work, the surface properties and electronic structure of two different perovskite single crystal compositions (MAPbI(3) and Cs(x)FA(1-x)PbI(3)) are investigated using synchrotron-based soft X-ray photoelectron spectroscopy (PES), molecular dynamics simulations, and density functional theory. The use of synchrotron-based soft X-ray PES enables high surface sensitivity and nondestructive depth-profiling. Core level and valence band spectra of the single crystals are presented. The authors find two carbon 1s contributions at the surface of MAPbI(3) and assign these to MA(+) ions in an MAI-terminated surface and to MA(+) ions below the surface. It is estimated that the surface is predominantly MAI-terminated but up to 30% of the surface can be PbI2-terminated. The results presented here can serve as reference spectra for photoelectron spectroscopy investigations of technologically relevant polycrystalline thin films, and the findings can be utilized to further optimize the design of device interfaces.

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  • 40.
    García Fernández, Alberto
    et al.
    Kungliga Tekniska Högskolan.
    Svanström, Sebastian
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Cody, M Sterling
    Stockholms Universitet.
    Gangan, Abhijeet
    Stockholm University.
    Erbing, Axel
    Stockholm University.
    Kamal, Chinnathambi
    Stockholms Universitet.
    Sloboda, Tamara
    Kungliga Tekniska Högskolan.
    Kammlander, Birgit
    Kungliga Tekniska Högskolan.
    Man, Gabriel
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Odelius, Michael
    Stockholms Universitet.
    Cappel, Ute B
    Kungliga Tekniska Högskolan.
    Experimental and theoretical core level and valence band analysis of clean perovskite single crystal surfaceIn: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095Article in journal (Other academic)
  • 41.
    Gerber, Evgeny
    et al.
    Lomonosov Moscow State Univ, Dept Chem, Moscow 119991, Russia.;Rossendorf Beamline ESRF European Synchrotron, CS40220, F-38043 Grenoble 9, France.;Inst Resource Ecol, Helmholtz Zentrum Dresden Rossendorf HZDR, POB 510119, D-01314 Dresden, Germany.
    Romanchuk, Anna Yu
    Lomonosov Moscow State Univ, Dept Chem, Moscow 119991, Russia.
    Weiss, Stephan
    Inst Resource Ecol, Helmholtz Zentrum Dresden Rossendorf HZDR, POB 510119, D-01314 Dresden, Germany.
    Kuzenkova, Anastasiia
    Lomonosov Moscow State Univ, Dept Chem, Moscow 119991, Russia.
    Hunault, Myrtille O. J. Y.
    LOrme Merisiers, Synchrotron SOLEIL, St Aubin BP 48, F-91192 Gif Sur Yvette, France.
    Bauters, Stephen
    Rossendorf Beamline ESRF European Synchrotron, CS40220, F-38043 Grenoble 9, France.;Inst Resource Ecol, Helmholtz Zentrum Dresden Rossendorf HZDR, POB 510119, D-01314 Dresden, Germany.
    Egorov, Alexander
    Lomonosov Moscow State Univ, Dept Chem, Moscow 119991, Russia.
    Butorin, Sergei
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Kalmykov, Stepan N.
    Lomonosov Moscow State Univ, Dept Chem, Moscow 119991, Russia.
    Kvashnina, Kristina O.
    Lomonosov Moscow State Univ, Dept Chem, Moscow 119991, Russia.;Rossendorf Beamline ESRF European Synchrotron, CS40220, F-38043 Grenoble 9, France.;Inst Resource Ecol, Helmholtz Zentrum Dresden Rossendorf HZDR, POB 510119, D-01314 Dresden, Germany.
    To form or not to form: PuO2 nanoparticles at acidic pH2022In: ENVIRONMENTAL SCIENCE-NANO, ISSN 2051-8153, Vol. 9, no 4, p. 1509-1518Article in journal (Refereed)
    Abstract [en]

    The aim of this study is to synthesize PuO2 nanoparticles (NPs) at low pH values and characterize the materials using laboratory and synchrotron-based methods. Properties of the PuO2 NPs formed under acidic conditions (pH 1-4) are explored here at the atomic scale. High-resolution transmission electron microscopy (HRTEM) is applied to characterize the crystallinity, morphology and size of the particles. It is found that 2 nm crystalline NPs are formed with a PuO2 crystal structure. High energy resolution fluorescence detected (HERFD) X-ray absorption spectroscopy at the Pu M-4 edge has been used to identify the Pu oxidation states and recorded data are analysed using the theory based on the Anderson impurity model (AIM). The experimental data obtained on NPs show that the Pu(iv) oxidation state dominates in all NPs formed at pH 1-4. However, the suspension at pH 1 demonstrates the presence of Pu(iii) and Pu(vi) in addition to the Pu(iv), which is associated with redox dissolution of PuO2 NPs under acidic conditions. We discuss in detail the mechanism that affects the PuO2 NPs synthesis under acidic conditions and compare it with one in neutral and alkaline conditions. Hence, the results shown here, together with the first Pu M-4 HERFD data on PuF3 and PuF4 compounds, are significant for the colloid facilitated transport governing the migration of plutonium in a subsurface environment.

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  • 42.
    Ghosh, Anirudha
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy. Lund Univ, MAXLab 4, POB 118, S-22100 Lund, Sweden..
    Jönsson, H. Johan M.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy. Asia Pacific Ctr Theoret Phys, Pohang 37673, South Korea..
    Mukkattukavil, D. John
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Kvashnin, Yaroslav
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Phuyal, Dibya
    KTH Royal Inst Technol, Dept Appl Phys, S-10691 Stockholm, Sweden..
    Thunström, Patrik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Agåker, Marcus
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Chemical and Bio-Molecular Physics. Lund Univ, MAXLab 4, POB 118, S-22100 Lund, Sweden..
    Nicolaou, Alessandro
    Synchrotron SOLEIL, Orme Merisiers, BP48, F-91192 Gif Sur Yvette, France..
    Jonak, Martin
    Heidelberg Univ, Kirchhoff Inst Phys, D-69120 Heidelberg, Germany..
    Klingeler, Ruediger
    Heidelberg Univ, Kirchhoff Inst Phys, D-69120 Heidelberg, Germany..
    Kamalakar, M. Venkata
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Sarkar, Tapati
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Vasiliev, Alexander N.
    Natl Univ Sci & Tech MISS, Moscow 119049, Russia.;Lomonosov Moscow State Univ, Moscow 119991, Russia.;Ural Fed Univ, Ekaterinburg 620002, Russia..
    Butorin, Sergei
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Eriksson, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Örebro Univ, Sch Sci & Technol, S-70182 Örebro, Sweden..
    Abdel-Hafiez, Mahmoud
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy. Univ Doha Sci & Technol, POB 24449, Doha, Qatar..
    Magnetic circular dichroism in the dd excitation in the van der Waals magnet CrI3 probed by resonant inelastic x-ray scattering2023In: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 107, no 11, article id 115148Article in journal (Refereed)
    Abstract [en]

    We report on a combined experimental and theoretical study on CrI3 single crystals by employing the polarization dependence of resonant inelastic x-ray scattering (RIXS). Our investigations reveal multiple Cr 3d orbital splitting (dd excitations) as well as magnetic dichroism (MD) in the RIXS spectra. The dd excitation energies are similar on the two sides of the ferromagnetic transition temperature, T-C similar to 61 K, although MD in RIXS is predominant at 0.4 T magnetic field below TC. This demonstrates that the ferromagnetic superexchange interaction that is responsible for the interatomic exchange field is vanishingly small compared with the local exchange field that comes from exchange and correlation interaction among the interacting Cr 3d orbitals. The recorded RIXS spectra reported here reveal clearly resolved Cr 3d intraorbital dd excitations that represent transitions between electronic levels that are heavily influenced by dynamic correlations and multiconfiguration effects. Our calculations taking into account the Cr 3d hybridization with the ligand valence states and the full multiplet structure due to intra-atomic and crystal field interactions in Oh and D3d symmetry clearly reproduced the dichroic trend in experimental RIXS spectra.

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  • 43.
    Ghosh, Anirudha
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Chemical and Bio-Molecular Physics.
    Singh, Deobrat
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Aramaki, T.
    Kyushu Inst Technol, Grad Sch Engn, Fukuoka 8048550, Japan..
    Mu, Qingge
    Max Planck Inst Chem Phys Solids, D-01187 Dresden, Germany..
    Borisov, Vladislav
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Kvashnin, Yaroslav
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Haider, G.
    Czech Acad Sci, J Heyrovsky Inst Phys Chem, Dolejskova 2155, Prague 18223, Czech Republic..
    Jonak, M.
    Heidelberg Univ, Kirchhoff Inst Phys, D-69120 Heidelberg, Germany..
    Chareev, D.
    Natl Univ Sci & Technol MISiS, Moscow 119049, Russia.;Inst Expt Mineral IEM RAS, Chernogolovka 142432, Moscow Region, Russia.;Ural Fed Univ, Ekaterinburg 620002, Russia..
    Medvedev, S. A.
    Max Planck Inst Chem Phys Solids, D-01187 Dresden, Germany..
    Klingeler, R.
    Heidelberg Univ, Kirchhoff Inst Phys, D-69120 Heidelberg, Germany..
    Mito, M.
    Kyushu Inst Technol, Grad Sch Engn, Fukuoka 8048550, Japan..
    Abdul-Hafidh, E. H.
    Taibah Univ, Fac Sci, Phys Dept, King Khalid Rd, Al Amoedi 46423, Yanbu El Bahr, Saudi Arabia..
    Vejpravova, J.
    Charles Univ Prague, Fac Math & Phys, Dept Condensed Matter Phys, Ke Karlovu 5, Prague 12116 2, Czech Republic..
    Kalbac, M.
    Czech Acad Sci, J Heyrovsky Inst Phys Chem, Dolejskova 2155, Prague 18223, Czech Republic..
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics. Uppsala Univ, Dept Phys & Astron, Box 516, SE-75120 Uppsala, Sweden..
    Eriksson, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics. Örebro Univ, Sch Sci & Technol, SE-70182 Örebro, Sweden..
    Abdel-Hafiez, Mahmoud
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Exotic magnetic and electronic properties of layered CrI3 single crystals under high pressure2022In: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 105, no 8, article id L081104Article in journal (Refereed)
    Abstract [en]

    Through advanced experimental techniques on CrI3 single crystals, we derive a pressure-temperature phase diagram. We find that T-c increases to similar to 66 K with pressure up to similar to 3 GPa followed by a decrease to similar to 10 K at 21.2 GPa. The experimental results are reproduced by theoretical calculations based on density functional theory where electron-electron interactions are treated by a static on-site Hubbard U on Cr 3d orbitals. The origin of the pressure-induced reduction of the ordering temperature is associated with a decrease in the calculated bond angle, from 95 degrees at ambient pressure to similar to 85 degrees at 25 GPa. Above 22 GPa, experiment and theory jointly point to the idea that the ferromagnetically ordered state is destroyed, giving rise first to a complex, unknown magnetic configuration, and at sufficiently high pressures a pure antiferromagnetic configuration. This sequence of transitions in the magnetism is accompanied by a well-detected pressure-induced semiconductor-to-metal phase transition that is revealed by both high-pressure resistivity measurements and ab initio theory.

  • 44.
    Grånäs, Oscar
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Vaskivskyi, I.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy. Univ Calif San Diego, Ctr Memory & Recording Res, 9500 Gilman Dr, La Jolla, CA 92093 USA..
    Wang, X.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Thunström, Patrik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Ghimire, S.
    SLAC Natl Accelerator Lab, Stanford PULSE Inst, 2575 Sand Hill Rd, Menlo Pk, CA 94025 USA..
    Knut, Ronny
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Söderström, Johan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Chemical and Bio-Molecular Physics.
    Kjellsson, L.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Turenne, Diego
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Engel, R. Y.
    DESY, Dept Photon Sci, Notkestr 85, D-22607 Hamburg, Germany..
    Beye, M.
    DESY, Dept Photon Sci, Notkestr 85, D-22607 Hamburg, Germany..
    Lu, J.
    SLAC Natl Accelerator Lab, Stanford PULSE Inst, 2575 Sand Hill Rd, Menlo Pk, CA 94025 USA..
    Higley, D. J.
    SLAC Natl Accelerator Lab, 2575 Sand Hill Rd, Menlo Pk, CA 94025 USA..
    Reid, A. H.
    SLAC Natl Accelerator Lab, 2575 Sand Hill Rd, Menlo Pk, CA 94025 USA..
    Schlotter, W.
    SLAC Natl Accelerator Lab, 2575 Sand Hill Rd, Menlo Pk, CA 94025 USA..
    Coslovich, G.
    SLAC Natl Accelerator Lab, 2575 Sand Hill Rd, Menlo Pk, CA 94025 USA.;Harvard Univ, John Paulson Sch Engn & Appl Sci, Cambridge, MA 02138 USA..
    Hoffmann, M.
    SLAC Natl Accelerator Lab, 2575 Sand Hill Rd, Menlo Pk, CA 94025 USA..
    Kolesov, G.
    Schissler-Langeheine, C.
    Helmholtz Zent Berlin Mat & Energie GmbH, D-12489 Berlin, Germany..
    Styervoyedov, A.
    Max Planck Inst Mikrostrukturphys, Weinberg 2, Halle, Germany..
    Tancogne-Dejean, N.
    Max Planck Inst Struct & Dynam Matter, Luruper Chaussee 149, D-22761 Hamburg, Germany.;Ctr Free Electron Laser Sci, Sch Sci & Technol, Luruper Chaussee 149, SE-70182 Hamburg, Germany..
    Sentef, M. A.
    Max Planck Inst Struct & Dynam Matter, Luruper Chaussee 149, D-22761 Hamburg, Germany.;Ctr Free Electron Laser Sci, Sch Sci & Technol, Luruper Chaussee 149, SE-70182 Hamburg, Germany..
    Reis, D. A.
    SLAC Natl Accelerator Lab, Stanford PULSE Inst, 2575 Sand Hill Rd, Menlo Pk, CA 94025 USA..
    Rubio, A.
    Max Planck Inst Struct & Dynam Matter, Luruper Chaussee 149, D-22761 Hamburg, Germany.;Ctr Free Electron Laser Sci, Sch Sci & Technol, Luruper Chaussee 149, SE-70182 Hamburg, Germany.;Flatiron Inst, Ctr Computat Quantum Phys, New York, NY 10010 USA..
    Parkin, S. S. P.
    Max Planck Inst Mikrostrukturphys, Weinberg 2, Halle, Germany..
    Karis, Olof
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Rubensson, J. -e.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Eriksson, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Dürr, Hermann
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Ultrafast modification of the electronic structure of a correlated insulator2022In: Physical Review Research, E-ISSN 2643-1564, Vol. 4, no 3, article id L032030Article in journal (Refereed)
    Abstract [en]

    A nontrivial balance between Coulomb repulsion and kinematic effects determines the electronic structure of correlated electron materials. The use of electromagnetic fields strong enough to rival these native microscopic interactions allows us to study the electronic response as well as the time scales and energies involved in using quantum effects for possible applications. We use element-specific transient x-ray absorption spectroscopy and high-harmonic generation to measure the response to ultrashort off-resonant optical fields in the prototypical correlated electron insulator NiO. Surprisingly, fields of up to 0.22 V/angstrom lead to no detectable changes in the correlated Ni 3d orbitals contrary to previous predictions. A transient directional charge transfer is uncovered, a behavior that is captured by first-principles theory. Our results highlight the importance of retardation effects in electronic screening and pinpoints a key challenge in functionalizing correlated materials for ultrafast device operation.

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    FULLTEXT01
  • 45. Gupta, Rahul
    et al.
    Cosco, F.
    Malik, R. S.
    Chen, X.
    Saha, Susmita
    Ghosh, A.
    Pohlmann, T.
    Mardegan, J. R. L.
    Francoual, S.
    Stefanuik, Robert
    Söderström, Johan
    Sanyal, Biplab
    Karis, Olof
    Svedlindh, Peter
    Oppeneer, P. M.
    Knut, Ronny
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Element-resolved evidence of superdiffusive spin current arising from ultrafast demagnetization process2023In: Phys. Rev. B, Vol. 108Article in journal (Refereed)
    Abstract [en]

    Using element-specific measurements of the ultrafast demagnetization of Ru/Fe65Co35 hetero-structures, we show that Ru can exhibit a significant magnetic contrast (3% asymmetry) resulting from ultrafast spin currents emanating from the demagnetization process of the FeCo layer. We use this magnetic contrast to investigate how superdiffusive spin currents are affected by the doping of heavy elements in the FeCo layer. We find that the spin currents are strongly suppressed, and that the recovery process in Ru slows down by Re doping. This is in accordance with a change in interface reflectivity of spin currents as found by the superdiffusive spin transport model.

  • 46.
    Gupta, Rahul
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Malik, Rameez Saeed
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Chen, Xin
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Department of Physics and Shenzhen Institute for Quantum Science & Engineering, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China.
    Saha, Susmita
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Ghosh, Anirudha
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Pohlmann, Tobias
    Deutsches Elektronen-Synchrotron (DESY), Notkestrasse 85, 22607 Hamburg, Germany.
    Renato Linares Mardegan, Jose
    Deutsches Elektronen-Synchrotron (DESY), Notkestrasse 85, 22607 Hamburg, Germany.
    Francoual, Sonia
    Deutsches Elektronen-Synchrotron (DESY), Notkestrasse 85, 22607 Hamburg, Germany.
    Rubensson, Jan-Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Sanyal, Biplab
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Karis, Olof
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Svedlindh, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Knut, Ronny
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Ultrafast Spin Dynamics of Ru in Ru/Fe65Co35/Ru heterostructures: Effect of Re dopingManuscript (preprint) (Other academic)
  • 47.
    Hakim, Charifa
    et al.
    Cadi Ayyad Univ, Fac Sci & Technol, Marrakech 40001, Morocco..
    Ma, Le Anh
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Duda, Laurent
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Younesi, Reza
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Brandell, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Saadoune, Ismael
    Cadi Ayyad Univ, Fac Sci & Technol, Marrakech 40001, Morocco.;Mohammed VI Polytech Univ, Technol Dev Cell Techcell, Ben Guerir 43150, Morocco..
    Anionic Redox and Electrochemical Kinetics of the Na2Mn3O7 Cathode Material for Sodium-Ion Batteries2022In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 36, no 7, p. 4015-4025Article in journal (Refereed)
    Abstract [en]

    Manganese-based layered oxides have gained wide attention as cathode materials for sodium-ion batteries due to their cost-effectiveness and nontoxicity. Among them, Na2Mn3O7, which shows promising electrochemical properties as a host material for sodium ions, has been extensively investigated recently. However, the charge compensation mechanisms during battery operation are still ambiguous. Herein, we investigate the electronic structure of Na2Mn3O7 using X-ray absorption spectroscopy (XAS) and resonant inelastic X-ray scattering techniques. Mn L-II,L-III-edge XAS spectra show that manganese ions do not undergo any oxidation reaction during the first charge process, suggesting that sodium removal is instead charge compensated by oxygen-ion redox reactions. This, in turn, has an impact on the cycling performances delivered by the material, especially the capacity retention over cycles and also the electrochemical kinetics of sodium ions in Na2Mn3O7.

    Download full text (pdf)
    fulltext
  • 48.
    Herstedt, Marie
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry.
    Andersson, Anna M
    ABB.
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Siegbahn, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Characterisation of the SEI formed on natural graphite in PC-based electrolytes2004In: Electrochimica Acta, ISSN 0013-4686, Vol. 49, p. 4939-4947Article in journal (Refereed)
  • 49.
    Hirsbrunner, Moritz
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Mikheenkova, Anastasiia
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Törnblom, Pontus
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    House, Robert A.
    Department of Materials, University of Oxford.
    Schmitt, Thorsten
    Swiss Light Source, Photon Science Division, Paul Scherrer Institut.
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Mukherjee, Soham
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Hahlin, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Duda, Laurent
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Vibrationally-resolved RIXS reveals OH-group formation in oxygen redox active Li-ion battery cathodes2023Other (Other academic)
  • 50.
    Hultman, Lars
    et al.
    Linköping Univ, Dept Sci & Technol, Wallenberg Initiat Mat Sci Sustainabil, Norrköping, Sweden.;Linköping Univ, Dept Phys, Thin Film Phys Div, IFM, S-58183 Linköping, Sweden..
    Mazur, Sara
    Linköping Univ, Dept Sci & Technol, Wallenberg Initiat Mat Sci Sustainabil, Norrköping, Sweden.;Knut & Alice Wallenberg Fdn, Stockholm, Sweden..
    Ankarcrona, Caroline
    Linköping Univ, Dept Sci & Technol, Wallenberg Initiat Mat Sci Sustainabil, Norrköping, Sweden.;Knut & Alice Wallenberg Fdn, Stockholm, Sweden..
    Palmqvist, Anders
    Linköping Univ, Dept Sci & Technol, Wallenberg Initiat Mat Sci Sustainabil, Norrköping, Sweden.;Chalmers Univ Technol, Dept Chem & Chem Engn, Gothenburg, Sweden..
    Abrahamsson, Maria
    Linköping Univ, Dept Sci & Technol, Wallenberg Initiat Mat Sci Sustainabil, Norrköping, Sweden.;Chalmers Univ Technol, Dept Chem & Chem Engn, Gothenburg, Sweden..
    Antti, Marta-Lena
    Linköping Univ, Dept Sci & Technol, Wallenberg Initiat Mat Sci Sustainabil, Norrköping, Sweden.;Luleå Univ Technol, Dept Engn Sci & Math, Div Mat Sci, Luleå, Sweden..
    Baltzar, Malin
    Linköping Univ, Dept Sci & Technol, Wallenberg Initiat Mat Sci Sustainabil, Norrköping, Sweden.;H2 Green Steel, Stockholm, Sweden..
    Bergstroem, Lennart
    Linköping Univ, Dept Sci & Technol, Wallenberg Initiat Mat Sci Sustainabil, Norrköping, Sweden.;Stockholm Univ, Dept Mat & Environm Chem, Stockholm, Sweden..
    de Laval, Pontus
    Linköping Univ, Dept Sci & Technol, Wallenberg Initiat Mat Sci Sustainabil, Norrköping, Sweden.;Knut & Alice Wallenberg Fdn, Stockholm, Sweden..
    Edman, Ludvig
    Linköping Univ, Dept Sci & Technol, Wallenberg Initiat Mat Sci Sustainabil, Norrköping, Sweden.;Umeå Univ, Dept Phys, Organ Photon & Elect Grp, Umeå, Sweden..
    Erhart, Paul
    Linköping Univ, Dept Sci & Technol, Wallenberg Initiat Mat Sci Sustainabil, Norrköping, Sweden.;Chalmers Univ Technol, Dept Phys, Gothenburg, Sweden..
    Kloo, Lars
    Linköping Univ, Dept Sci & Technol, Wallenberg Initiat Mat Sci Sustainabil, Norrköping, Sweden.;KTH Royal Inst Technol, Dept Chem, Appl Phys Chem, SE-10044 Stockholm, Sweden..
    Lundberg, Mats W.
    Linköping Univ, Dept Sci & Technol, Wallenberg Initiat Mat Sci Sustainabil, Norrköping, Sweden.;Sandvik AB, Stockholm, Sweden..
    Mikkelsen, Anders
    Linköping Univ, Dept Sci & Technol, Wallenberg Initiat Mat Sci Sustainabil, Norrköping, Sweden.;Lund Univ, NanoLund Ctr Nanosci, Lund, Sweden.;Lund Univ, Dept Phys, Lund, Sweden..
    Moons, Ellen
    Linköping Univ, Dept Sci & Technol, Wallenberg Initiat Mat Sci Sustainabil, Norrköping, Sweden.;Karlstad Univ, Dept Engn & Phys, Mat Sci Res, Karlstad, Sweden..
    Persson, Cecilia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering. Linköping Univ, Dept Sci & Technol, Wallenberg Initiat Mat Sci Sustainabil, Norrköping, Sweden.
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials. Linköping Univ, Dept Sci & Technol, Wallenberg Initiat Mat Sci Sustainabil, Norrköping, Sweden.
    Rosen, Johanna
    Linköping Univ, Dept Sci & Technol, Wallenberg Initiat Mat Sci Sustainabil, Norrköping, Sweden.;Linköping Univ, Mat Design Div, Dept Phys Chem & Biol IFM, Linköping, Sweden..
    Ruden, Christina
    Linköping Univ, Dept Sci & Technol, Wallenberg Initiat Mat Sci Sustainabil, Norrköping, Sweden.;Stockholm Univ, Dept Environm Sci, Stockholm, Sweden..
    Selleby, Malin
    Linköping Univ, Dept Sci & Technol, Wallenberg Initiat Mat Sci Sustainabil, Norrköping, Sweden.;KTH Royal Inst Technol, Stockholm, Sweden..
    Sundgren, Jan-Eric
    Linköping Univ, Dept Sci & Technol, Wallenberg Initiat Mat Sci Sustainabil, Norrköping, Sweden.;Swedish Natl Agcy Educ, Stockholm, Sweden..
    Dick Thelander, Kimberly
    Linköping Univ, Dept Sci & Technol, Wallenberg Initiat Mat Sci Sustainabil, Norrköping, Sweden.;Lund Univ, Ctr Anal & Synth, Lund, Sweden.;Lund Univ, NanoLund, Lund, Sweden..
    Tybrandt, Klas
    Linköping Univ, Dept Sci & Technol, Wallenberg Initiat Mat Sci Sustainabil, Norrköping, Sweden.;Linköping Univ, Dept Sci & Technol, Lab Organ Elect, Norrköping, Sweden..
    Weihed, Paer
    Linköping Univ, Dept Sci & Technol, Wallenberg Initiat Mat Sci Sustainabil, Norrköping, Sweden.;Luleå Univ Technol, Dept Civil Environm & Nat Resources Engn, Luleå, Sweden..
    Zou, Xiaodong
    Linköping Univ, Dept Sci & Technol, Wallenberg Initiat Mat Sci Sustainabil, Norrköping, Sweden.;Stockholm Univ, Dept Mat & Environm Chem, Stockholm, Sweden..
    Astrand, Maria
    Linköping Univ, Dept Sci & Technol, Wallenberg Initiat Mat Sci Sustainabil, Norrköping, Sweden.;Northvolt AB, Stockholm, Sweden..
    Platzer Björkman, Charlotte
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy. Linköping Univ, Dept Sci & Technol, Wallenberg Initiat Mat Sci Sustainabil, Norrköping, Sweden.
    Schneider, Jochen M.
    Linköping Univ, Dept Sci & Technol, Wallenberg Initiat Mat Sci Sustainabil, Norrköping, Sweden.;Rhein Westfal TH Aachen, Inst Pathol, Aachen, Germany..
    Eriksson, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Linköping Univ, Dept Sci & Technol, Wallenberg Initiat Mat Sci Sustainabil, Norrköping, Sweden..
    Berggren, Magnus
    Linköping Univ, Dept Sci & Technol, Wallenberg Initiat Mat Sci Sustainabil, Norrköping, Sweden.;Linköping Univ, Dept Sci & Technol, Lab Organ Elect, Norrköping, Sweden..
    Advanced materials provide solutions towards a sustainable world2024In: Nature Materials, ISSN 1476-1122, E-ISSN 1476-4660, Vol. 23, no 2, p. 160-161Article in journal (Other academic)
123 1 - 50 of 144
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