Change search
Refine search result
1234567 151 - 200 of 1949
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 151. Belonoshko, Anatoly B.
    et al.
    Ahuja, R.
    Johansson, Börje
    Molecular dynamics of LiF melting2000In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 61, no 18, p. 11928-11935Article in journal (Refereed)
    Abstract [en]

    We performed molecular-dynamics simulations of the melting and/or freezing of LiF. The simulations were done using the Tosi-Fumi model and our own model of interatomic interactions. The latter was verified by ab initio calculations of the equation of state for LiF. We show that the recent molecular-dynamics calculations by Boehler and co-workers are not adequate and their model for the interactions is not capable of providing melting temperatures in agreement with experiment. Our calculated pressure dependence of the melting temperatures gives valuable information. We found that the B1-B2 transition in LiF at around 1 Mbar removes the discrepancy between the diamond-anvil cell and shockwave melting temperatures. An explanation of the controversy between low and high melting temperatures obtained from diamond-anvil cell experiments is suggested.

  • 152.
    Belonoshko, Anatoly B.
    et al.
    KTH, School of Engineering Sciences (SCI), Theoretical Physics, Condensed Matter Theory.
    Arapan, Sergiu
    KTH, School of Engineering Sciences (SCI), Theoretical Physics, Condensed Matter Theory.
    Martonak, R.
    Rosengren, Anders
    KTH, School of Engineering Sciences (SCI), Theoretical Physics, Condensed Matter Theory.
    MgO phase diagram from first principles in a wide pressure-temperature range2010In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 81, no 5, p. 054110-1-054110-9Article in journal (Refereed)
    Abstract [en]

    Recent laser-initiated strong shockwave measurements at Livermore provide the opportunity for verification of the MgO phase diagram at extreme pressures and temperatures. This calls for a comprehensive study of the MgO phase diagram. The phase diagram is obtained by ab initio molecular dynamics (two phase and Z method) and phonon-based thermodynamic calculations. Energies and forces are computed from first principles projector augmented wave method. The B1 transforms to B2 phase at about 490 GPa. Melting temperatures of B1 are consistent with the two-phase melting curve (Alfe, 2005). The triple point B1-B2-liquid is located at about 2.4 Mbar and 9000 K. The melting curve of the B2 phase rises rather steeply from the triple point. The Hugoniot is likely to cross the B1-B2 boundary first and then to cross the melting curve of B2, therefore, the melting curve of periclase is not relevant for the Hugoniot. MgO melts between 11.3 and 12.5 thousand K and 4.3 and 5 Mbar along the Hugoniot from the B2 phase. The two-phase melting curves of B1 computed with various semiempirical potentials are remarkably close to each other and are consistent with the B1 first principles melting curve at low pressure. This suggests the MgO melting temperatures to be in the close proximity of this determination. The search for new phases of MgO by first principles metadynamics has not produced unknown phases. Therefore, the suggested discontinuity of the Hugoniot at 170 GPa and 3000 K remains enigmatic.

  • 153.
    Belonoshko, Anatoly B.
    et al.
    KTH, School of Engineering Sciences (SCI), Theoretical Physics, Condensed Matter Theory.
    Dorogokupets, P. I.
    Johansson, Börje
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    Saxena, S. K.
    Koci, L.
    Ab initio equation of state for the body-centered-cubic phase of iron at high pressure and temperature2008In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 78, no 10Article in journal (Refereed)
    Abstract [en]

    The solid inner core of the Earth consists mostly of iron. There is accumulating evidence that, at the extreme pressures and temperatures of the deep Earth interior, iron stabilizes in the body-centered-cubic phase. However, experimental study of iron at those conditions is very difficult at best. We demonstrate that our ab initio approach is capable of providing volumetric data on iron in very good agreement with experiment at low temperature and high pressure. Since our approach treats high-temperature effects explicitly, this allows us to count on similar precision also at high temperature and high pressure. We perform ab initio molecular-dynamics simulations at a number of volume-temperature conditions and compute the corresponding pressures. These points are then fitted with an equation of state. A number of parameters are computed and compared with existing data. The obtained equation of state for high pressure and temperature nonmagnetic body-centered-cubic phase allows the computation of properties of iron under extreme conditions of the Earth's inner core.

  • 154.
    Belonoshko, Anatoly B.
    et al.
    KTH, School of Engineering Sciences (SCI), Theoretical Physics, Condensed Matter Theory.
    Isaev, E. I.
    Skorodumova, N. V.
    Johansson, Börje
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    Stability of the body-centered-tetragonal phase of Fe at high pressure: Ground-state energies, phonon spectra, and molecular dynamics simulations2006In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 74, no 21Article in journal (Refereed)
    Abstract [en]

    It is well established that at a pressure of several megabars and low temperature Fe is stable in the hexagonal-close-packed (hcp) phase. However, there are indications that on heating a high-pressure hcp phase of Fe transforms to a less dense (open structure) phase. Two phases have been suggested as candidates for these high-temperature stable phases: namely, body-centered-cubic and body-centered-tetragonal (bct) phases. We performed first-principles molecular dynamics and phonon analysis of the bct Fe phase and demonstrated its dynamical instability. This allows us to dismiss the existence of the bct Fe phase under the high-pressure high-temperature conditions of the Earth's inner core.

  • 155.
    Belonoshko, Anatoly B.
    et al.
    KTH, School of Engineering Sciences (SCI), Theoretical Physics, Condensed Matter Theory.
    Rosengren, Anders
    KTH, School of Engineering Sciences (SCI), Theoretical Physics, Condensed Matter Theory.
    High-pressure melting curve of platinum from ab initio Z method2012In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 85, no 17, p. 174104-Article in journal (Refereed)
    Abstract [en]

    Pt is widely used as a standard in high-pressure high-temperature experiments. The available experimental and theoretical data on Pt thermal stability is not consistent. We address the issue of high-pressure Pt melting by ab initio molecular dynamics. We demonstrate a remarkable consistency of our computed melting curve with the experimental data by N. R. Mitra, D. L. Decker, and H. B. Vanfleet [Phys. Rev. 161, 613 (1967)]. The extrapolation of their data, based on the Simon equation, nearly coincides with our ab initio computed melting curve. We propose the Pt melting curve in the form P-m(kbar) = 443.0[(T/T-m)(1.14) - 1].

  • 156.
    Belonoshko, Anatoly B.
    et al.
    KTH, School of Engineering Sciences (SCI), Theoretical Physics, Condensed Matter Theory. KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    Rosengren, Anders
    KTH, School of Engineering Sciences (SCI), Theoretical Physics, Condensed Matter Theory.
    Burakovsky, Leonid
    Preston, Dean L.
    Johansson, Börje
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    Melting of Fe and Fe0.9375Si0.0625 at Earth's core pressures studied using ab initio molecular dynamics2009In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 79, no 22Article in journal (Refereed)
    Abstract [en]

    The issue of melting of pure iron and iron alloyed with lighter elements at high pressure is critical to the physics of the Earth. The iron melting curve in the relevant pressure range between 3 and 4 Mbar is reasonably well established from the theoretical point of view. However, so far no one attempted a direct atomistic simulation of iron alloyed with light elements. We investigate here the impact of alloying the body-centered cubic (bcc) Fe with Si. We simulate melting of the bcc Fe and Fe0.9375Si0.0625 alloy by ab initio molecular dynamics. The addition of light elements to the hexagonal-close-packed (hcp) iron is known to depress its melting temperature (T-m). We obtain, in marked contrast, that alloying of bcc Fe with Si does not lead to T-m depression; on the contrary, the T-m slightly increases. This suggests that if Si is a typical impurity in the Earth's inner core, then the stable phase in the core is bcc rather than hcp.

  • 157. Belonoshko, Anatoly B.
    et al.
    Rosengren, Anders
    Burakovsky, Leonid
    Preston, L
    Johansson, Börje
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Melting of Fe and Fe0.9375Si0.0625 at Earth's core pressures studied using ab initio molecular dynamics2009In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 79, no 22, p. 220102-Article in journal (Refereed)
    Abstract [en]

    The issue of melting of pure iron and iron alloyed with lighter elements at high pressure is critical to the physics of the Earth. The iron melting curve in the relevant pressure range between 3 and 4 Mbar is reasonably well established from the theoretical point of view. However, so far no one attempted a direct atomistic simulation of iron alloyed with light elements. We investigate here the impact of alloying the body-centered cubic (bcc) Fe with Si. We simulate melting of the bcc Fe and Fe0.9375Si0.0625 alloy by ab initio molecular dynamics. The addition of light elements to the hexagonal-close-packed (hcp) iron is known to depress its melting temperature (T-m). We obtain, in marked contrast, that alloying of bcc Fe with Si does not lead to T-m depression; on the contrary, the T-m slightly increases. This suggests that if Si is a typical impurity in the Earth's inner core, then the stable phase in the core is bcc rather than hcp.

  • 158.
    Belonoshko, Anatoly B.
    et al.
    KTH, Superseded Departments, Physics.
    Rosengren, Anders
    KTH, Superseded Departments, Physics.
    Dong, Qian
    KTH, Superseded Departments, Materials Science and Engineering.
    Hultquist, Gunnar
    KTH, Superseded Departments, Materials Science and Engineering.
    Leygraf, Christofer
    KTH, Superseded Departments, Materials Science and Engineering.
    First-principles study of hydrogen diffusion in alpha-Al2O3 and liquid alumina2004In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 69, no 2Article in journal (Refereed)
    Abstract [en]

    We have studied the energetics and mobility of neutral hydrogen in alumina Al2O3 using ab initio density-functional calculations. The mobility of hydrogen was studied in corundum (alpha-Al2O3) as well as in liquid alumina. Using both static as well as molecular-dynamics calculations, and applying classical transition state theory, we derive the temperature-dependent diffusivity of hydrogen in alpha-Al2O3 as D(T)=(21.7x10(-8) m(2)/s)exp(-1.24 eV/kT). The corresponding diffusivity of hydrogen in liquid/amorphous alumina, derived directly from ab initio molecular dynamics calculations, is D(T)=(8.71x10(-7) m(2)/s)exp(-0.91 eV/kT). The computed diffusivity compares very well to experimental data. We conclude that diffusion of neutral hydrogen through the bulk of alumina is a good approximation of the mechanism for hydrogen mobility in corrosion scales. The representation of grain-boundary structures by amorphous alumina is, probably, realistic at higher temperatures.

  • 159.
    Belonoshko, Anatoly B.
    et al.
    KTH, School of Engineering Sciences (SCI), Theoretical Physics, Condensed Matter Theory.
    Skorodumova, N. V.
    Rosengren, Anders
    KTH, School of Engineering Sciences (SCI), Theoretical Physics, Condensed Matter Theory.
    Johansson, Börje
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    Melting and critical superheating2006In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 73, no 1Article in journal (Refereed)
    Abstract [en]

    Two mechanisms of melting are known, heterogeneous, where melting starts at surfaces, and homogeneous, where the liquid nucleates in the bulk crystal. If melting occurs homogeneously, a crystal can be superheated significantly above its melting temperature (T-m). At present, the physical meaning of the limit of superheating (T-LS) is unknown. We demonstrate, by molecular dynamics simulations, that the total energy of a solid at T-LS is equal to the total energy of its liquid at T-m at the same volume. In the high pressure limit T-LS and T-m are connected by the constant k(AB)=ln 2/3 via the relation k(AB)=T-LS/T-m-1.

  • 160.
    Belonoshko, Anatoly
    et al.
    KTH, School of Engineering Sciences (SCI), Theoretical Physics, Condensed Matter Theory.
    Koči, L.
    Rosengren, Anders
    KTH, School of Engineering Sciences (SCI), Theoretical Physics, Condensed Matter Theory.
    Stability of the bcc phase of 4He close to the melting curve: A molecular dynamics study2012In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 85, no 1, p. 012503-Article in journal (Refereed)
    Abstract [en]

    We have investigated whether the Aziz et al. [J. Chem. Phys. 70, 4330 (1979)] model for (4)He renders the body-centered cubic phase more stable than the face-centered cubic phase in the proximity of the melting curve. Using molecular dynamics, we have simulated these solid phases in equilibrium with the liquid at a number of densities. In contrast to previous free energy molecular dynamics calculations, the model stabilizes the body-centered cubic phase. The stability field is just 5 degrees. wide below the melting curve at pressures around 140 Kbar and about 70 degrees wide at pressures around 750 Kbar. Considering that the body-centered cubic phase is dynamically unstable at low temperature, this result bears striking similarities to transition metal phase diagrams.

  • 161. Belotelov, V. I.
    et al.
    Kreilkamp, L. E.
    Kalish, A. N.
    Akimov, I. A.
    Bykov, D. A.
    Kasture, S.
    Yallapragada, V. J.
    Gopal, A. V.
    Grishin, Alexander M.
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Khartsev, Sergiy I.
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Nur-E-Alam, M.
    Vasiliev, M.
    Doskolovich, L. L.
    Yakovlev, D. R.
    Alameh, K.
    Zvezdin, A. K.
    Bayer, M.
    Magnetophotonic intensity effects in hybrid metal-dielectric structures2014In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 89, no 4, p. 045118-Article in journal (Refereed)
    Abstract [en]

    The magneto-optical properties of a hybrid metal-dielectric structure consisting of a one-dimensional gold grating on top of a magnetic waveguide layer are studied experimentally and theoretically. It is demonstrated that a magnetic field applied in the longitudinal configuration (in the plane of the magnetic film and perpendicular to the slits in the gold grating) to the metal-dielectric structure modifies the field distribution of the optical modes and thus changes the mode excitation conditions. In the optical far field, this manifests in the alteration of the optical transmittance or reflectance when the structure becomes magnetized. This magneto-optical effect is shown to represent a novel class of effects related to the magnetic-field-induced modification of the Bloch modes of the periodic hybrid structure. That is why we define this effect as "longitudinal magnetophotonic intensity effect" (LMPIE). The LMPIE has two contributions, odd and even in magnetization. While the even LMPIE is maximal for the light polarized perpendicular to the grating slits (TM) and minimal for the orthogonal polarization (TE), the odd LMPIE takes maximum values at some intermediate polarization and vanishes for pure TM and TE polarizations. Two principal modes of the magnetic layer - TM and TE - acquire in the longitudinal magnetic field additional field components and thus turn into quasi-TM and quasi-TE modes, respectively. The largest LMPIE is observed for excitation of the antisymmetrical quasi-TE mode by TM-polarized light. The value of the LMPIE measured for the plasmonic structure with a magnetic film of Bi2Dy1Fe4Ga1O12 composition is about 1% for the even effect and 2% for the odd one. However, the plasmonic structure with a magnetic film with a higher concentration of bismuth (Bi2.97Er0.03Fe4Al0.5Ga0.5O12) gives significantly larger LMPIE: even LMPIE reaches 24% and odd LMPIE is 9%. Enhancement of the magneto-optical figure of merit (defined as the ratio of the specific Faraday angle of a magnetic film to its absorption coefficient) of the magnetic films potentially causes the even LMPIE to exceed 100% as is predicted by calculations. Thus, the nanostructured material described here may be considered as an ultrafast magnetophotonic light valve.

  • 162. Bengone, O.
    et al.
    Eriksson, O.
    Fransson, Jonas
    KTH, Superseded Departments, Materials Science and Engineering.
    Turek, I.
    Kudrnovsky, J.
    Drchal, V.
    Electronic structure and transport properties of CrAs/GaAs/CrAs trilayers from first principles theory2004In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 70, no 3Article in journal (Refereed)
    Abstract [en]

    We present a theoretical study of the transport properties of a CrAs/GaAs/CrAs trilayer. The theory was based on a first principles method for calculating the electronic structure, in combination with a Kubo-Landauer approach for calculating the transport properties in a current perpendicular to the plane geometry. We have also investigated the electronic structure and the magnetic properties of this trilayer, with special focus on electronic and magnetic properties at the CrAs/GaAs interface. Finally, we have studied the effects of chemical disorder on the transport properties, in particular the influence of As antisites at both the Cr and Ga sites.

  • 163.
    Bengone, Oliver
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Eriksson, O
    Fransson, J
    Turek, I
    Kudrnovsky, J
    Drchal, V
    Electronic structure and transport properties of CrAs/GaAs/CrAs trilayers from first principles theory2004In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 70, no 3, p. 035302-Article in journal (Refereed)
    Abstract [en]

    We present a theoretical study of the transport properties of a CrAs/GaAs/CrAs trilayer. The theory was based on a first principles method for calculating the electronic structure, in combination with a Kubo-Landauer approach for calculating the transport properties in a current perpendicular to the plane geometry. We have also investigated the electronic structure and the magnetic properties of this trilayer, with special focus on electronic and magnetic properties at the CrAs/GaAs interface. Finally, we have studied the effects of chemical disorder on the transport properties, in particular the influence of As antisites at both the Cr and Ga sites.

  • 164.
    Bengone, Oliver
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Eriksson, O
    Mirbt, S
    Turek, I
    Kudrnovsky, J
    Drchal, V
    Origin of the negative giant magnetoresistance effect in Co1-xCrx/Cu/Co (111) trilayers2004In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 69, no 9, p. 092406-Article in journal (Refereed)
    Abstract [en]

    We present a theoretical study on Co1-xCrx/Cu/Co (111) trilayers, where a transition from positive to negative giant magnetoresistance effect has been observed experimentally, with increasing thickness of the alloyed layer. The theory, based on a recently implemented conductance calculation, reproduces quantitatively this observation, and the effect is found to be caused by alloying effects, due to a virtual bound Cr d state in the majority spin channel of the Co-Cr layer.

  • 165. Benza, V G
    et al.
    Canali, Carlo M.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Strini, G
    Landau-Zener quantum tunneling in disordered nanomagnets2004In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 70, no 18, p. 1844261-9-184426-9Article in journal (Refereed)
  • 166.
    Berggren, Karl-Fredrik
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics .
    Yakimenko, II
    Effects of exchange and electron correlation on conductance and nanomagnetism in ballistic semiconductor quantum point contacts2002In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 66, no 8Article in journal (Refereed)
    Abstract [en]

    The spontaneous magnetization of a quantum point contact (QPC) formed between two large quantum dots by a lateral confinement of a high-mobility two-dimensional electron gas is studied for a realistic GaAs/AlxGa1-xAs heterostructure. The model of the device incorporates the contributions from a patterned gate, doping, surface states, and mirror charges. To explore the magnetic properties, the Kohn-Sham local spin-density formalism is used with exchange and correlation potentials that allows for local spin polarization. Exchange is the dominant mechanism behind local magnetization within the QPC, while the correlation part is less prominent. However, the correlation potential gives rise to an important correction in the QPC potential. Below the first conduction plateau we thus find a magnetized regime corresponding approximately to a single electron spin. Using an approximate separable saddle potential we compute the conductance and recover the so-called similar to0.7 (2e(2)/h) conduction anomaly plus an additional anomaly at similar to0.4 (2e(2)/h) below which the magnetization collapses.

  • 167.
    Berggren, Peter
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Fransson, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Stability and chaos of a driven nanoelectromechanical Josephson junction2012In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 85, no 19, p. 195439-Article in journal (Refereed)
    Abstract [en]

    We consider the motion of and Josephson current through a mechanically oscillating superconducting island asymmetrically embedded in a Josephson junction. The electromechanical coupling is provided by distance-dependent tunneling rates between the electrodes and the island. The system asymmetry, resulting from the geometrical configuration, leads, for weak coupling, to an equation of the mechanical motion that reduces to the well-known Duffing equation. At zero bias voltage the island motion is determined by the homogenous Duffing equation that opens up two separate regions of solutions depending on the superconducting phases. The island either moves under influence of an anharmonic single-well potential or is governed by a double-well potential that allows for off-center oscillations. Under applied bias voltage the island equation of motion turns into a modified Duffing equation, with time-dependent coefficients, that demonstrate both quasiperiodic and chaotic behavior.

  • 168.
    Berggren, Peter
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Fransson, Jonas
    Theory of spin inelastic tunneling spectroscopy for superconductor-superconductor and superconductor-metal junctions2015In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 91, no 20, article id 205438Article in journal (Refereed)
    Abstract [en]

    We address the tunneling conductance and spin inelastic tunneling spectroscopy of localized paramagnetic moments in a superconducting environment, pertaining to recent measurements on Fe-octaethylporphyrin-chloride using superconducting scanning tunneling microscopy. We demonstrate that the Cooper pair correlations in the tip and substrate generate a finite uniaxial anisotropy field acting on the local spin moment, and we argue that this field may be a source for the observed changes in the conductance spectrum for decreasing distance between the scanning tunneling tip and the local magnetic moment. We make a side-by-side comparison between the superconductor-superconductor junction and normal-metal-superconductor junction, and find qualitative agreement between the two setups while quantitative differences become explicit. When simulating the effects of electron pumping, we obtain additional peaks in the conductance spectrum that can be attributed to excitations between higher-energy spin states. The transverse anisotropy field couples basis states of the local spin which opens for transitions between spin states that are otherwise forbidden by conservation of angular momentum. Finally, we explore the influences of temperature, which tend to enable in-gap transitions, and an external magnetic field, which enables deeper studies of the spin excitation spectrum. We especially notice the appearance of a low and high excitation peak on each side of the main coherence peak as an imprint of transitions between the Zeeman split ground states.

  • 169.
    Bergholtz, E. J.
    et al.
    Stockholm University, Faculty of Science, Department of Physics.
    Kailasvuori, J.
    Stockholm University, Faculty of Science, Department of Physics.
    Wikberg, Emma
    Stockholm University, Faculty of Science, Department of Physics.
    Hansson, Thors Hans
    Stockholm University, Faculty of Science, Department of Physics.
    Karlhede, Anders
    Stockholm University, Faculty of Science, Department of Physics.
    Pfaffian quantum Hall state made simple: Multiple vacua and domain walls on a thin torus2006In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 74, no 8, p. 081308-Article in journal (Refereed)
    Abstract [en]

    We analyze the Moore-Read Pfaffian state on a thin torus. The known sixfold degeneracy is realized by two inequivalent crystalline states with a four- and twofold degeneracy, respectively. The fundamental quasihole and quasiparticle excitations are domain walls between these vacua, and simple counting arguments give a Hilbert space of dimension 2n−1 for 2n−k holes and k particles at fixed positions and assign each a charge ±e∕4. This generalizes the known properties of the hole excitations in the Pfaffian state as deduced using conformal field theory techniques. Numerical calculations using a model Hamiltonian and a small number of particles support the presence of a stable phase with degenerate vacua and quarter-charged domain walls also away from the thin-torus limit. A spin-chain Hamiltonian encodes the degenerate vacua and the various domain walls.

  • 170. Bergman, Anders
    et al.
    Burkert, Till
    Sanyal, Biplab
    Frota-Pessoa, Sonia
    Nordstrom, Lars
    Ruban, Andrei V.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    Simak, Sergei I.
    Eriksson, Olle
    Magnetic properties of Fe/Co(001) superlattices from first-principles theory2006In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 74, no 17Article in journal (Refereed)
    Abstract [en]

    The magnetic properties of Fe/Co(001) superlattices have been studied using fully-relativistic first-principles theories. The average magnetic moment shows a behavior similar to bulk Fe-Co alloys, i.e., an enhanced magnetic moment for low Co concentrations, as described by the Slater-Pauling curve. The maximum of the magnetization curve, however, is lowered and shifted towards the Fe-rich compositions. The increased average magnetic moment for the Fe-rich superlattices, compared to bulk Fe, is due to an enhancement of the Fe spin moment close to the Fe-Co interface. The orbital moments were found to be of the same size as in bulk. The effect of interface roughness on the magnetic properties was investigated, and it was found that-despite local fluctuations due to the varying coordination-the average magnetic moment is only slightly affected. From a mapping of first-principles interactions onto the screened generalized perturbation method, we calculate the temperatures for when Fe/Co superlattices break up into an alloy configuration. Furthermore, the tetragonal distortion of the superlattice structure was found to only have a minor effect on the magnetic moments. Also, the calculated easy axis of magnetization is in the film plane for all compositions studied. It lies along the [100] direction for Fe-rich superlattices and along the [110] direction for Co-rich compositions. The transition of the easy axis occurs around a Co concentration of 50%.

  • 171.
    Bergman, Anders
    et al.
    Uppsala University.
    Burkert, Till
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics.
    Sanyal, Biplab
    Uppsala University.
    Frota-Pessôa, Sonia
    Universidade de Saõ Paulo.
    Nordström, Lars
    Uppsala University.
    Ruban, Andrei V.
    Royal Institute of Technology.
    Simak, Sergey
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics.
    Eriksson, Olle
    Uppsala University.
    Magnetic properties of Fe /Co(001) superlattices from first- principles theory2006In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 74, p. 174409-1-174409-7Article in journal (Refereed)
  • 172.
    Bergman, Anders
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Burkert, Till
    Sanyal, Biplab
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Frota-Pessôa, Sonia
    Nordström, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Ruban, Andrei.V.
    Simak, Sergei.I.
    Eriksson, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Magnetic properties of Fe/Co(001) superlattices from first-principles theory2006In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 74, no 17, p. 174409-Article in journal (Refereed)
    Abstract [en]

    The magnetic properties of Fe/Co(001) superlattices have been studied using fully-relativistic first-principles theories. The average magnetic moment shows a behavior similar to bulk Fe-Co alloys, i.e., an enhanced magnetic moment for low Co concentrations, as described by the Slater-Pauling curve. The maximum of the magnetization curve, however, is lowered and shifted towards the Fe-rich compositions. The increased average magnetic moment for the Fe-rich superlattices, compared to bulk Fe, is due to an enhancement of the Fe spin moment close to the Fe-Co interface. The orbital moments were found to be of the same size as in bulk. The effect of interface roughness on the magnetic properties was investigated, and it was found that-despite local fluctuations due to the varying coordination-the average magnetic moment is only slightly affected. From a mapping of first-principles interactions onto the screened generalized perturbation method, we calculate the temperatures for when Fe/Co superlattices break up into an alloy configuration. Furthermore, the tetragonal distortion of the superlattice structure was found to only have a minor effect on the magnetic moments. Also, the calculated easy axis of magnetization is in the film plane for all compositions studied. It lies along the [100] direction for Fe-rich superlattices and along the [110] direction for Co-rich compositions. The transition of the easy axis occurs around a Co concentration of 50%.

  • 173.
    Bergman, Anders
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Eriksson, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Magnetic moments of Fe clusters embedded in an Fe-Co alloy2006In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 74, no 10, p. 104422-Article in journal (Refereed)
    Abstract [en]

    Motivated by the search for high moment materials, we present first-principles calculations of the magnetic moments for Fe clusters embedded in an Fe-Co alloy as well as in a pure Co matrix. Both spin and orbital contributions have been calculated with the use of a real-space linear muffin-tin orbital method within the atomic sphere approximation. The cluster sizes considered range from 1 to 51 atoms. We find an enhancement of the spin moments of the atoms close to the interface between the cluster and the embedding matrix. The spin moment enhancement is decreasing with increasing Fe content in the surrounding matrix. The slightly lower magnetic moments for the Fe clusters embedded in the Fe rich matrices can nevertheless result in a material with an enhanced saturation magnetization due to the higher moments in the matrix. We argue that the largest average magnetic moments for embedded Fe clusters are obtained for an Fe0.5Co0.5 alloy in the matrix surrounding the clusters.

  • 174.
    Bergman, Anders
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Theoretical Magnetism.
    Holmström, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Theoretical Magnetism.
    Niklasson, A.M.N.
    Nordström, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Condensed Matter Theory.
    Frota-Pessôa, Sonia
    Eriksson, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Theoretical Magnetism.
    Magnetism of Fe clusters embedded in a Co matrix from first-principles theory2004In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 70, no 17, p. 174446-Article in journal (Refereed)
    Abstract [en]

    We have calculated spin and orbital moments for Fe clusters of sizes up to 700 atoms embedded as impurities in a bcc Co matrix. The calculations have been carried out using relativistic first-principles real-space density functional theory, and we have made a comparison with earlier experimental studies. For Fe atoms close to theFeCo interface, the spin moments are found to increase while atoms far from the interface exhibit bulklike moments. The Co moments remain essentially unchanged and close to the moment of bulk bcc Co. With increasing cluster size, the average moments of the cluster atoms decrease due to the decreased surface to volume ratio. The orbital moments of both Fe and Co are calculated to be small and they stay almost constant regardless of cluster size. Our results for spin moments agree with experimental data but the calculated orbital moments are slightly underestimated. A simplified model indicates that a compound of close-packed Fe clusters surrounded by Co show higher average total moments compared to bulk and multilayer systems with a similar concentration. This increase seems to disappear when cluster-cluster interactions are taken into account. The general trend is that for a given alloy concentration of FexCo1−x, clustering tends to lower the average magnetic moment compared to that of ordered structures and random alloys.

  • 175.
    Bergman, Anders
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Nordström, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Klautau, Angela Burlamaqui
    Frota-Pessoa, Sonia
    Eriksson, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Magnetic structures of small Fe, Mn, and Cr clusters supported on Cu(111): Noncollinear first-principles calculations2007In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 75, no 22, p. 224425-Article in journal (Refereed)
    Abstract [en]

    The magnetic structures of small clusters of Fe, Mn, and Cr supported on a Cu(111) surface have been studied with noncollinear first-principles theory. Different geometries such as triangles, pyramids, and wires are considered and the cluster sizes have been varied between two and ten atoms. The calculations have been performed using a real-space linear muffin-tin orbital method. The Fe clusters are found to order ferromagnetically regardless of the cluster geometry. For Mn and Cr clusters, antiferromagnetic exchange interactions between nearest neighbors are found to cause collinear antiferromagnetic ordering when the geometry allows it. If the antiferromagnetism is frustrated by the cluster geometry, noncollinear ordering is found. A comparison between the calculated structures and ground states obtained from simplified Heisenberg Hamiltonians show that the exchange interaction varies for different atoms in the clusters as a result of the different local structure.

  • 176.
    Bergman, Anders
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    Skubic, B
    Hellsvik, J
    Nordstrom, L
    Delin, Anna
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    Eriksson, O
    Ultrafast switching in a synthetic antiferromagnetic magnetic random-access memory device2011In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 83, no 22Article in journal (Refereed)
    Abstract [en]

    The dynamics of a synthetic antiferromagnet (a metallic trilayer) have been explored and are shown to exhibit ultrafast switching on a time scale of tens of ps. This conclusion is based on first-principles, atomistic spin dynamics simulations. The simulations are performed at finite temperature, as well as at T = 0 K (the macrospin limit), and we observe a marked temperature dependence of the switching phenomenon. It is shown that, to reach very high switching speeds, it is important that the two ferromagnetic components of the synthetic antiferromagnet have oppositely directed external fields to one another. Then a complex collaboration between precession switching of an internal exchange field and the damping switching of the external field occurs, which considerably accelerates the magnetization dynamics. We discuss a possible application of this fast switching as a magnetic random access memory device, which has as a key component intrinsic antiferromagnetic couplings and an applied Oersted field.

  • 177.
    Bergman, Anders
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Skubic, Björn
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Hellsvik, Johan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Nordström, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Delin, Anna
    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.
    Ultrafast switching in a synthetic antiferromagnetic magnetic random-access memory device2011In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 83, no 22, p. 224429-Article in journal (Refereed)
    Abstract [en]

    The dynamics of a synthetic antiferromagnet (a metallic trilayer) have been explored and are shown to exhibit ultrafast switching on a time scale of tens of ps. This conclusion is based on first-principles, atomistic spin dynamics simulations. The simulations are performed at finite temperature, as well as at T = 0 K (the macrospin limit), and we observe a marked temperature dependence of the switching phenomenon. It is shown that, to reach very high switching speeds, it is important that the two ferromagnetic components of the synthetic antiferromagnet have oppositely directed external fields to one another. Then a complex collaboration between precession switching of an internal exchange field and the damping switching of the external field occurs, which considerably accelerates the magnetization dynamics. We discuss a possible application of this fast switching as a magnetic random access memory device, which has as a key component intrinsic antiferromagnetic couplings and an applied Oersted field.

  • 178.
    Bergman, Anders
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Taroni, Andrea
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Bergqvist, Lars
    Uppsala University, Sweden.
    Hellsvik, Johan
    Hjörvarsson, Björgvin
    Eriksson, Olle
    Magnon softening in a ferromagnetic monolayer: A first-principles spin dynamics study2010In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 81, no 14, p. 144416-Article in journal (Refereed)
    Abstract [en]

    We study the Fe/W(110) monolayer system through a combination of first-principles calculations and atomistic spin dynamics simulations. We focus on the dispersion of the spin-waves parallel to the [001] direction. Our results compare favorably with the experimental data of Prokop et al. [Phys. Rev. Lett. 102, 177206 (2009)] and correctly capture a drastic softening of the magnon spectrum, with respect to bulk bcc Fe. The suggested shortcoming of the itinerant electron model, in particular that given by density functional theory, is refuted. We also demonstrate that finite-temperature effects are significant, and that atomistic spin dynamics simulations represent a powerful tool with which to include these.

  • 179.
    Bergman, Anders
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Taroni, Andrea
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Bergqvist, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Hellsvik, Johan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Hjörvarsson, Björgvin
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Eriksson, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Magnon softening in a ferromagnetic monolayer: A first-principles spin dynamics study2010In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 81, no 14, p. 144416-Article in journal (Refereed)
    Abstract [en]

    We study the Fe/W(110) monolayer system through a combination of first-principles calculations and atomistic spin dynamics simulations. We focus on the dispersion of the spin-waves parallel to the [001] direction. Our results compare favorably with the experimental data of Prokop et al. [Phys. Rev. Lett. 102, 177206 (2009)] and correctly capture a drastic softening of the magnon spectrum, with respect to bulk bcc Fe. The suggested shortcoming of the itinerant electron model, in particular that given by density functional theory, is refuted. We also demonstrate that finite-temperature effects are significant, and that atomistic spin dynamics simulations represent a powerful tool with which to include these.

  • 180.
    Bergqvist, Lars
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Material Physics, MF.
    Atomistic spin dynamics of low-dimensional magnets2013In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 87, no 14, p. 144401-Article in journal (Refereed)
    Abstract [en]

    We investigate the magnetic properties of a range of low-dimensional ferromagnets using a combination of first-principles calculations and atomistic spin dynamics simulations. This approach allows us to evaluate the ground state and finite temperature properties of experimentally well characterized systems such as Co/Cu(111), Co/Cu(001), Fe/Cu(001) and Fe/W(110), for different thicknesses of the magnetic layer. We compare our calculated spin wave spectra with experimental data available in the literature, and find a good quantitative agreement. We also predict magnon spectra for systems for which no experimental data exist at the moment, and estimate the role of temperature effects.

  • 181.
    Bergqvist, Lars
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Theoretical Magnetism.
    Eriksson, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Theoretical Magnetism.
    Kudrnovsky, Josef
    Drchal, Vaclav
    Bergman, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Theoretical Magnetism.
    Nordström, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Condensed Matter Theory.
    Turek, Ilja
    Magnetic properties and disorder effects in diluted magnetic semiconductors2005In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 72, no 19, p. 195210-Article in journal (Refereed)
    Abstract [en]

    We present calculations of the exchange interactions and critical temperatures for several diluted magnetic semiconductor systems. It is shown that the exchange interactions are dominated by short-ranged interactions that have a strong directional dependence. Using a combination of first-principles calculations of the exchange interactions together with Monte Carlo simulations of the classical Heisenberg model, in which the positional disorder and spin fluctuations are properly included, the calculated critical temperatures are in good agreement with experimantal observations. It is shown that agreement between theory and experiment, as regards ordering temperatures, is obtained only when the magnetic atoms are randomly positioned in a simulation cell which proves that disorder effects play a very important role. The effect of strong electron-electron interaction has been studied by means of the LSDA+U scheme. We investigate in detail the nature of the anisotropic exchange interactions by means of a Fermi surface analysis.

  • 182.
    Bergqvist, Lars
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    Korzhavyi, Pavel A.
    KTH, Superseded Departments, Materials Science and Engineering.
    Sanyal, B.
    Mirbt, S.
    Abrikosov, I. A.
    Nordstrom, L.
    Smirnova, E. A.
    Mohn, P.
    Svedlindh, P.
    Eriksson, O.
    Magnetic and electronic structure of (Ga1-xMnx)As2003In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 67, no 20, p. 205201-Article in journal (Refereed)
    Abstract [en]

    We present theoretical calculations of the magnetic and electronic structure of Mn-doped GaAs (in the zinc-blende structure). The magnetic properties are shown to be very sensitive to structural defects, in particular, As antisite defects and Mn at interstitial positions. Only when considering such defects can the experimental magnetic moments be reproduced by first-principles theory. We present a simple model for understanding the connection between the magnetic ordering and the As antisites, and the way in which the defects help to stabilize a partial disordered local-moment state. The connection between the energetics of the Mn substitution and the As antisite concentration is also analyzed. In addition, we compare the calculated magnetic properties and electronic structures of Mn situated on substitutional sites (Mn replacing a Ga atom) and on interstitial sites, where in agreement with observations the interstitial site is found to be less favorable. Finally, combining our first-principles calculations of the spin-wave excitation energies with a classical Heisenberg Hamiltonian we have calculated interatomic exchange interactions, and using Monte Carlo simulations we present theoretical values of the critical temperature as a function of Mn concentration.

  • 183.
    Bergqvist, Lars
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Theoretical Magnetism.
    Korzhavyi, Pavel
    Sanyal, Biplab
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Condensed Matter Theory.
    Mirbt, Susanne
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Condensed Matter Theory.
    Abrikosov, Igor
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Nordström, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Condensed Matter Theory.
    Smirnova, E.
    Mohn, Peter
    Svedlindh, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science.
    Eriksson, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Theoretical Magnetism.
    Magnetic and electronic structure of (Ga1-xMnx)As2003In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 67, no 20, p. 205201-Article in journal (Refereed)
  • 184.
    Bergqvist, Lars
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    Sato, K.
    Katayama-Yoshida, H.
    Dederichs, P. H.
    Computational materials design for high-T(c) (Ga, Mn)As with Li codoping2011In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 83, no 16, article id 165201Article in journal (Refereed)
    Abstract [en]

    Based on first-principles calculations and kinetic Monte Carlo simulations, we design a realistic and practical codoping technique for increasing the concentration of Mn atoms in GaAs and realizing high Curie temperatures in (Ga, Mn) As. We found that using codoping of Li interstitial atoms during the crystal growth has two great advantages. First, due to lower formation energy of Li interstitials compared to Mn interstitials, Li prevents formation of unwanted Mn interstitials. Second, Li interstitials can be removed by using post-growth annealing at low temperatures. This codoping method offers a general strategy to go far beyond the solubility limit and it should be applicable also to other diluted magnetic semiconductor systems.

  • 185.
    Bernad, Joszef Zsolt
    et al.
    Massey University.
    Jääskeläinen, Markku
    Dalarna University. Institute of Fundamental Sciences and MacDiarmid Institute for Advanced Materials and Nanotechnology, Massey University, Palmerston North, New Zealand.
    Zulicke, Ulrich
    Massey University.
    Effects of a quantum measurement on the electric conductivity: Application to graphene2010In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 81, no 7, article id 073403Article in journal (Refereed)
    Abstract [en]

    We generalize the standard linear-response (Kubo) theory to obtain the conductivity of a system that is subject to a quantum measurement of the current. Our approach can be used to specifically elucidate how back-action inherent to quantum measurements affects electronic transport. To illustrate the utility of our general formalism, we calculate the frequency-dependent conductivity of graphene and discuss the effect of measurement-induced decoherence on its value in the dc limit. We are able to resolve an ambiguity related to the parametric dependence of the minimal conductivity.

  • 186. Berner, G.
    et al.
    Glawion, S.
    Walde, J.
    Pfaff, F.
    Hollmark, H.M.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Duda, Laurent-Claudius
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Paeterl, S.
    Richter, C.
    Mannhart, J.
    Sing, M.
    Claessen, R.
    LaAlO3/SrTiO3 oxide heterostructures studied by resonant inelastic x-ray scattering2010In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 82, no 24, article id 241405Article in journal (Refereed)
  • 187. Berner, G.
    et al.
    Glawion, S.
    Walde, J.
    Pfaff, F.
    Hollmark, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Soft X-Ray Physics.
    Duda, Laurent
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Soft X-Ray Physics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Surface and Interface Science.
    Paetel, S.
    Richter, C.
    Mannhart, J.
    Sing, M.
    Claessen, R.
    LaAlO3/SrTiO3 oxide heterostructures studied by resonant inelastic x-ray scattering2010In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 82, no 24, p. 241405-Article in journal (Refereed)
    Abstract [en]

    We report the application of resonant inelastic X-ray scattering to explore the nature of the single conducting interface in the oxide heterostructure LaAlO/sub 3//SrTiO/sub 3/. From the Ti 3d crystal-field excitations measured at the Ti L/sub 3/ resonance we not only derive information on the local geometry at the interface but are also able to follow the evolution of the sheet carrier density with the thickness of the LaAlO/sub 3/ overlayer. These findings confirm after calibration to previous hard X-ray photoelectron spectroscopy measurements that the charge density from spectroscopy exceeds the one derived from Hall-effect measurements, indicating the coexistence of itinerant /i and/ localized Ti 3d electrons at the interface. On the other hand, we observe a saturation of the charge-carrier concentration above a LaAlO/sub 3/ thickness of 6 unit cells at ~1*10/sup 14/ cm/sup -2/, well below the canonical value for ideal electronic reconstruction.

  • 188.
    Berntsen, Magnus H.
    et al.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Material Physics, MF.
    Götberg, Olof
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Material Physics, MF.
    Wojek, Bastian M.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Material Physics, MF.
    Tjernberg, Oscar
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Material Physics, MF.
    Direct observation of decoupled Dirac states at the interface between topological and normal insulators2013In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 88, no 19, article id 195132Article in journal (Refereed)
    Abstract [en]

    Several proposed applications and exotic effects in topological insulators rely on the presence of helical Dirac states at the interface between a topological insulator and a normal insulator. In the present work, we have used low-energy angle-resolved photoelectron spectroscopy to uncover and characterize the interface states of Bi2Se3 thin films and Bi2Te3/Bi2Se3 heterostructures grown on Si(111). The results establish that Dirac fermions are indeed present at the topological-normal-insulator boundary and absent at the topological-topological-insulator interface. Moreover, it is demonstrated that band bending present within the topological-insulator films leads to a substantial separation of the interface and surface states in energy. These results pave the way for further studies and the realization of interface-related phenomena in topological-insulator thin-film heterostructures.

  • 189.
    Berrier, Audrey
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Swillo, Marcin
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Le Thomas, N.
    Ecole Polytech Fed Lausanne, Inst Photon & Elect Quant.
    Houdré, R.
    Ecole Polytech Fed Lausanne, Inst Photon & Elect Quant.
    Anand, Srinivasan
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Bloch mode excitation in two-dimensional photonic crystals imaged by Fourier optics2009In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 79, no 16, p. 165116-1-165116-6Article in journal (Refereed)
    Abstract [en]

    Coupling into the Bloch modes of a two-dimensional photonic crystal (PhC) field is investigated by Fourier optics. The PhC was designed to operate in the second band above the air-light line, close to the autocollimation regime for TE polarization. The sample was fabricated in an InP-based heterostructure and an access ridge waveguide provides in-plane excitation of the PhC. The spatial Fourier transform of the field maps obtained from finite-difference time-domain simulations and those calculated by plane-wave expansion are compared to the experimentally obtained equifrequency surfaces (EFS). The shape of the imaged EFS and its variation with the excitation wavelength is shown to be consistent with the theoretical simulations. Finally, the results indicate that if combined with different excitation geometries, Fourier optics can be a powerful technique to assess photonic crystal devices and to design efficient structures.

  • 190.
    Bhandary, Sumanta
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Brena, Barbara
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Panchmatia, Pooja M.
    Brumboiu, Iulia
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Bernien, Matthias
    Weis, Claudia
    Krumme, Bernhard
    Etz, Corina
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Kuch, Wolfgang
    Wende, Heiko
    Eriksson, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Sanyal, Biplab
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Manipulation of spin state of iron porphyrin by chemisorption on magnetic substrates2013In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 88, no 2, p. 024401-Article in journal (Refereed)
    Abstract [en]

    One of the key factors behind the rapid evolution of molecular spintronics is the efficient realization of spin manipulation of organic molecules with a magnetic center. The spin state of such molecules may depend crucially on the interaction with the substrate on which they are adsorbed. In this paper we demonstrate, using ab initio density functional calculations, that the stabilization of a high spin state of an iron porphyrin (FeP) molecule can be achieved via chemisorption on magnetic substrates of different species and orientations, viz., Co(001), Ni(001), Ni(110), and Ni(111). The signature of chemisorption of FeP on magnetic substrates is evident from broad features in N K x-ray absorption (XA) and Fe L-2,L-3 x-ray magnetic circular dichroism (XMCD) measurements. Our theoretical calculations show that the strong covalent interaction with the substrate increases Fe-N bond lengths in FeP and hence a switching to a high spin state (S = 2) from an intermediate spin state (S = 1) is achieved. Due to chemisorption, ferromagnetic exchange interaction is established through a direct exchange between Fe and substrate magnetic atoms as well as through an indirect exchange via the N atoms in FeP. The mechanism of exchange interaction is further analyzed by considering structural models constructed from ab initio calculations. Also, it is found that the exchange interaction between Fe in FeP and a Ni substrate is almost 4 times smaller than with a Co substrate. Finally, we illustrate the possibility of detecting a change in the molecular spin state by XMCD, Raman spectroscopy, and spin-polarized scanning tunneling microscopy.

  • 191.
    Bhandary, Sumanta
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Eriksson, Olle
    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.
    Katsnelson, Mikhail I.
    Complex edge effects in zigzag graphene nanoribbons due to hydrogen loading2010In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 82, no 16, p. 165405-Article in journal (Refereed)
    Abstract [en]

    We have performed density-functional calculations as well as employed a tight-binding theory, to study the effect of passivation of zigzag graphene nanoribbons (ZGNR) by hydrogen. We show that each edge C atom bonded with 2 H atoms open up a gap and destroys magnetism for small widths of the nanoribbon. However, a re-entrant magnetism accompanied by a metallic electronic structure is observed from eight rows and thicker nanoribbons. The electronic structure and magnetic state are quite complex for this type of termination, with sp(3) bonded edge atoms being nonmagnetic whereas the nearest neighboring atoms are metallic and magnetic. We have also evaluated the phase stability of several thicknesses of ZGNR and demonstrate that sp(3) bonded edge atoms with 2 H atoms at the edge can be stabilized over 1 H atom terminated edge at high temperatures and pressures.

  • 192.
    Bhandary, Sumanta
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Grånäs, Oscar
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Szunyogh, Laszlo
    Sanyal, Biplab
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Nordström, Lars
    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.
    Route towards finding large magnetic anisotropy in nanocomposites: Application to a W(1-x)Re(x)/Fe multilayer2011In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 84, no 9, p. 092401-Article in journal (Refereed)
    Abstract [en]

    We suggest here a nanolaminate, 5[Fe]/2[W(x)Re(1-x)] (x = 0.6-0.8), with enhanced magnetic hardness in combination with a large saturation moment. The calculated magnetic anisotropy of this material reaches values of 5.3-7.0 MJ/m(3), depending on alloying conditions. We also propose a recipe in how to identify other novel magnetic materials, such as nanolaminates and multilayers, with large magnetic anisotropy in combination with a high saturation moment.

  • 193.
    Bhowmick, Somnath
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Rusz, Jan
    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.
    X-ray absorption spectra: Graphene, h-BN, and their alloy2013In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 87, no 15, p. 155108-Article in journal (Refereed)
    Abstract [en]

    Using first-principles density functional theory calculations, in conjunction with the Mahan-Nozieres-de Dominicis theory, we calculate the x-ray absorption spectra of the alloys of graphene and monolayer hexagonal boron nitride on a Ni (111) substrate. The chemical neighborhood of the constituent atoms (B, C, and N) inside the alloy differs from that of the parent phases. In a systematic way, we capture the change in the K-edge spectral shape, depending on the chemical neighborhood of B, C, and N. Our work also reiterates the importance of the dynamical core-hole screening for a proper description of the x-ray absorption process in sp(2)-bonded layered materials.

  • 194. Biasini, M
    et al.
    Rusz, Jan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Mills, A. P., Jr.
    Positron annihilation study of the electronic structure of URu2Si2: Fermi surface and hidden order parameter2009In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 79, no 8, p. 085115-Article in journal (Refereed)
    Abstract [en]

    The Fermi surface (FS) of URu2Si2 in the paramagnetic phase has been reinvestigated via the measurement of the two-dimensional angular correlation of the positron annihilation radiation. Unlike previous measurements our experiment provides evidence that density-functional theory gives a fair qualitative description of the FS, showing a large contribution from the 5f electrons, although the Fermi volume of electron and hole pockets determined experimentally is smaller than the theoretical description. Furthermore, we propose a method to investigate the nature of the hidden order responsible for the 17.5 K transition.

  • 195.
    Bielecki, Johan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Molecular biophysics.
    Rata, A. D.
    Borjesson, L.
    Femtosecond optical reflectivity measurements of lattice-mediated spin repulsions in photoexcited LaCoO3 thin films2014In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 89, no 3, p. 035129-Article in journal (Refereed)
    Abstract [en]

    We present results on the temperature dependence of ultrafast electron and lattice dynamics, measured with pump-probe transient reflectivity experiments, of an epitaxially grown LaCoO3 thin film under tensile strain. Probing spin-polarized transitions into the antibonding e(g) band provides a measure of the low-spin fraction, both as a function of temperature and time after photoexcitation. It is observed that femtosecond laser pulses destabilize the constant low-spin fraction (similar to 63%-64%) in equilibrium into a thermally activated state, driven by a subpicosecond change in spin gap Delta. From the time evolution of the low-spin fraction, it is possible to disentangle the thermal and lattice contributions to the spin state. A lattice mediated spin repulsion, identified as the governing factor determining the equilibrium spin state in thin-film LaCoO3, is observed. These results suggests that time-resolved spectroscopy is a sensitive probe of the spin state in LaCoO3 thin films, with the potential to bring forward quantitative insight into the complicated interplay between structure and spin state in LaCoO3.

  • 196.
    Biltmo, Anders
    et al.
    KTH, School of Engineering Sciences (SCI), Theoretical Physics.
    Henelius, Patrik
    KTH, School of Engineering Sciences (SCI), Theoretical Physics, Condensed Matter Theory.
    Low-temperature properties of the dilute dipolar magnet LiHoxY1-xF42008In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 78, no 5Article in journal (Refereed)
    Abstract [en]

    We analyze recent experiments on the dilute rare-earth compound LiHoxY1-xF4 in the context of an effective Ising dipolar model. Using a Monte Carlo method we calculate the low-temperature behavior of the specific heat and linear susceptibility and compare our results to measurements. In our model the susceptibility follows a Curie-Weiss law at high temperature, X similar to 1 / (T- T-cw), with a Curie-Weiss temperature that scales with dilution, T-cw similar to x, consistent with early experiments. We also find that the peak in the specific heat scales linearly with dilution, C-max(T)similar to x, in disagreement with recent experiments. This difference could be caused by the hyperfine interaction which is not included in our calculation. Experimental studies do not reach a consensus on the functional form of the susceptibility and specific heat, and in particular, we do not see reported scalings of the form X similar to T-0.75 and X similar to exp(-T/T-0). Furthermore, we calculate the ground-state magnetization as a function of dilution and re-examine the phase diagram around the critical dilution x, = 0.24 +/- 0.03. We find that the spin-glass susceptibility for the Ising model does not diverge below x, while some recent experiments give strong evidence for a stable spin-glass phase in LiHo0.167Y0.833F4.

  • 197.
    Biltmo, Anders
    et al.
    KTH, School of Engineering Sciences (SCI), Theoretical Physics.
    Henelius, Patrik
    KTH, School of Engineering Sciences (SCI), Theoretical Physics, Condensed Matter Theory.
    Phase diagram of the dilute magnet LiHoxY1-xF42007In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 76, no 5Article in journal (Refereed)
    Abstract [en]

    We study the effective long-range Ising dipole model with a local exchange interaction appropriate for the dilute magnetic compound LiHoxY1-xF4. Our calculations yield a value of 0.12 K for the nearest-neighbor exchange interaction. Using a Monte Carlo method, we calculate the phase boundary T-c(x) between the ferromagnetic and paramagnetic phases. We demonstrate that the experimentally observed linear decrease in T-c with dilution is not the simple mean-field result, but a combination of the effects of fluctuations and the exchange interaction. Furthermore, we find a critical dilution x(c)=0.21(2), below which there is no ordering. In agreement with recent Monte Carlo simulations on a similar model, we find no evidence of the experimentally observed freezing of the glassy state in our calculation. We apply the theory of Stephen and Aharony to LiHoxY1-xF4 and find that the theory does predict a finite-temperature freezing of the spin glass. Reasons for the discrepancies are discussed.

  • 198. Bjorkqvist, M
    et al.
    Gothelid, M
    Grehk, T M
    Karlsson, Ulf
    KTH, School of Information and Communication Technology (ICT).
    NH3 on Si(111)7x7: Dissociation and surface reactions1998In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 57, no 4, p. 2327-2333Article in journal (Refereed)
    Abstract [en]

    Core-level and valence-band photoelectron spectroscopy on the dissociative adsorption of ammonia on Si(111) 7 X 7 is presented. Adsorption at room temperature produces three nitrogen 1s components, of which two are assigned to NH2 and one to NH, with an initial tendency for double dissociation. These doubly dissociated species can be connected to the development of silicon atoms coordinated with two nitrogen atoms, necessitating silicon-silicon bonds to be broken. The dominating picture evolving is thus adatoms saturated by NH2 with a NH group inserted into one backbond, and hydrogen preferentially capping restatoms. The dissociation proces is hence much more complex than generally proposed before. This is further accentuated by the fact that not all adatoms appear reacted. When annealed above 600 K the dissociation process progresses and atomic nitrogen appears at 700 K, to be the only remaining specie at 850 K. At 1200 K, further changes in the N 1s core level indicates true silicon nitride formation.

  • 199. Bjornangen, T.
    et al.
    Rydh, A.
    Rapp, Östen.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Multiterminal transport measurements: In-plane anisotropy and vortex liquid correlation in YBa2Cu3O7-delta2001In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 64, no 22Article in journal (Refereed)
    Abstract [en]

    Using a modified pseudoflux transformer geometry, the in-plane anisotropy and vortex-liquid correlation of an untwinned YBa2Cu3O7-delta single crystal have been studied. The square-shaped, multiterminal sample design allows comparative studies of a- and b-axis properties for arbitrarily oriented magnetic fields. We compare the in-plane resistivity in the case of intrinsic pinning with the longitudinal resistivity, i.e., with the resistivity in absence of a macroscopic Lorentz force. The relative ratio between resistivities rho (a) and rho (b) in the vortex state can be made to vary over a wide range by controlling the direction of the applied magnetic field. Evidence is found for almost isotropic fluctuations corresponding to a fluctuation anisotropy gamma (A)(ab)approximate to1.1, noted to be clearly lower than the anisotropy gamma (ab)=1.27 obtained from the vortex phase diagram.

  • 200. Bjornson, Kristofer
    et al.
    Pershoguba, Sergey S.
    KTH, Centres, Nordic Institute for Theoretical Physics NORDITA.
    Balatsky, Alexander V.
    KTH, Centres, Nordic Institute for Theoretical Physics NORDITA. Los Alamos National Laboratory, United States.
    Black-Schaffer, Annica M.
    Spin-polarized edge currents and Majorana fermions in one- and two-dimensional topological superconductors2015In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 92, no 21, article id 214501Article in journal (Refereed)
    Abstract [en]

    We investigate the persistent currents, spin-polarized local density of states, and spectral functions of topological superconductors constructed by placing ferromagnetic impurities on top of an s-wave superconductor with Rashba spin-orbit interaction. We solve self-consistently for the superconducting order parameter and investigate both two-dimensional blocks and one-dimensional wires of ferromagnetic impurities, with the magnetic moments pointing both perpendicular and parallel to the surface. We find that the topologically protected edge states of ferromagnetic blocks give rise to spin-polarized edge currents, but that the total persistent current flows in opposite direction to what is expected from the dispersion relation of the edge states. We also show that the Majorana fermions at the end points of one-dimensional wires are spin polarized, which can be directly related to the spin polarization of the edge currents of two-dimensional blocks. Connections are also made to the physics of the Yu-Shiba-Rusinov states for zero-dimensional impurities.

1234567 151 - 200 of 1949
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf