Change search
CiteExportLink to record
Permanent link

Direct 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
Structure formation, phase transitions and drag interactions in multicomponent superconductors and superfluids
KTH, School of Engineering Sciences (SCI), Physics, Statistical Physics.
2018 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Superconductivity and superfluidity are some of the most funda-mental and important phenomena of modern physics. However, muchtheoretical work for such systems so far has been restricted to the one-component case. For multicomponent systems, the spectrum of possible topological defects, their structure formation and associated phasetransitions, can all be much richer than in the one-component case, motivating theoretical studies of multicomponent systems.

In this thesis, the structure formation of vortices with complicated interactions due to multicomponent effects are considered using point-particle Monte Carlo simulations. Besides the triangular vortex latticesfound for one-component type-2 superconducting vortices, it is found that a rich plethora of structural phases is possible for vortices in mul-ticomponent systems.

Since vortices play a key role in phase transitions, the problem of phase transitions in multicomponent systems is also studied in thisthesis. It could be expected that U(1) lattice London superconductorscan only have a continuous “inverted-XY” phase transition by a Peskin-Dasgupta-Halperin duality argument for the one-component case. Itis discussed here that the non-trivial internal structure of vortices in multicomponent U(1) London superconductors can instead lead to a first-order phase transition, which is supported by large-scale parallel tempering Monte Carlo simulations. Even for such systems, wherein the ground state vortex lines are axially symmetric, thermally induced splitting of composite vortices into fractional vortices can lead to a phase separation of vortex tangles, rendering the superconducting phase transition first-order.

A similar phase separation can occur for two-component superconductors with an Andreev-Bashkin drag interaction, for which a phase separation can occur even in the ground state: the drag can cause com-posite vortices to decay into attractively interacting skyrmions. Suchdrag interactions can to a large extent influence phase transitions, rotational response and vortex structures in multicomponent systems. Thisthesis thus finishes with microscopic calculations of such an Andreev-Bashkin drag interaction in an extended Bose-Hubbard model of two-species bosons in an optical lattice, using worm quantum Monte Carlosimulations. Dependencies of the drag interaction on boson-boson in-teractions and properties of the optical lattice are characterized, andpaired phases (where only co- or counter-flow states occur) are observed.

Place, publisher, year, edition, pages
Kungliga tekniska högskolan, 2018. , p. 79
Series
TRITA-FYS, ISSN 0280-316X ; 2017:78
National Category
Condensed Matter Physics
Research subject
Physics
Identifiers
URN: urn:nbn:se:kth:diva-221081ISBN: 978-91-7729-657-7 OAI: oai:DiVA.org:kth-221081DiVA, id: diva2:1173323
Public defence
2018-02-09, FB42, AlbaNova, Roslagstullsbacken 21, Stockholm, 14:00 (English)
Opponent
Supervisors
Note

QC 20180115

Available from: 2018-01-15 Created: 2018-01-12 Last updated: 2018-01-15Bibliographically approved
List of papers
1. First-order phase transition and tricritical point in multiband U(1) London superconductors
Open this publication in new window or tab >>First-order phase transition and tricritical point in multiband U(1) London superconductors
2016 (English)In: PHYSICAL REVIEW B, ISSN 2469-9950, Vol. 93, no 5, article id 054524Article in journal (Refereed) Published
Abstract [en]

The order of the superconducting phase transition is a classical problem. Single-component type-2 superconductors exhibit a continuous "inverted-XY" phase transition, as was first demonstrated for U(1) lattice London superconductors by a celebrated duality mapping with subsequent backing by numerical simulations. Here we study this problem in multiband U(1) London superconductors and find evidence that by contrast the model has a tricritical point. The superconducting phase transition becomes first order when the Josephson length is sufficiently large compared to the magnetic field penetration length. We present evidence that the fluctuation-induced dipolar interaction between vortex loops makes the phase transition discontinuous. We discuss that this mechanism is also relevant for the phase transitions in multicomponent gauge theories with higher broken symmetry.

Place, publisher, year, edition, pages
American Physical Society, 2016
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-184967 (URN)10.1103/PhysRevB.93.054524 (DOI)000371391800006 ()2-s2.0-84960157429 (Scopus ID)
Note

QC 20160407

Available from: 2016-04-07 Created: 2016-04-07 Last updated: 2018-01-12Bibliographically approved
2. Superfluid drag in the two-component Bose-Hubbard model
Open this publication in new window or tab >>Superfluid drag in the two-component Bose-Hubbard model
(English)Manuscript (preprint) (Other academic)
Abstract [en]

In multicomponent superfluids and superconductors, co- and counter-flows of components have in general different properties. It was discussed in 1975 by Andreev and Bashkin, in the context of He3/He4 superfluid mixtures, that inter-particle interactions produce a dissipationless drag. The drag can be understood as a superflow of one component induced by phase gradients of the other component. Importantly the drag can be both positive (entrainment) and negative (counter-flow). The effect is known to be of crucial importance for many properties of diverse physical systems ranging from the dynamics of neutron stars, rotational responses of Bose mixtures of ultra-cold atoms to magnetic responses of multicomponent superconductors. Although there exists a substantial literature that includes the drag interaction phenomenologically, much fewer regimes are covered by quantitative studies of the microscopic origin of the drag and its dependence on microscopic parameters. Here we study the microscopic origin and strength of the drag interaction in a quantum system of two-component bosons on a lattice with short-range interaction. By performing quantum Monte-Carlo simulations of a two-component Bose-Hubbard model we obtain dependencies of the drag strength on the boson-boson interactions and properties of the optical lattice. Of particular interest are the strongly-correlated regimes where the ratio of co-flow and counter-flow superfluid stiffnesses can diverge, corresponding to the case of saturated drag.

National Category
Condensed Matter Physics
Research subject
Physics
Identifiers
urn:nbn:se:kth:diva-221080 (URN)
Note

QC 20180115

Available from: 2018-01-12 Created: 2018-01-12 Last updated: 2018-01-15Bibliographically approved
3. Hierarchical structure foramtion in layered superconducting systems with multi-scale inter-vortex interactions
Open this publication in new window or tab >>Hierarchical structure foramtion in layered superconducting systems with multi-scale inter-vortex interactions
Show others...
2013 (English)In: Journal of Physics: Condensed Matter, ISSN 0953-8984, E-ISSN 1361-648X, Vol. 25, no 41, p. 415702-Article in journal (Refereed) Published
Abstract [en]

We demonstrate the formation of hierarchical structures in two-dimensional systems with multiple length scales in the inter-particle interaction. These include states such as clusters of clusters, concentric rings, clusters inside a ring, and stripes in a cluster. We propose to realize such systems in vortex matter (where a vortex is mapped onto a particle with multi-scale interactions) in layered superconducting systems with varying inter-layer thicknesses and different layer materials.

Keywords
Vortices
National Category
Other Physics Topics
Identifiers
urn:nbn:se:kth:diva-132201 (URN)10.1088/0953-8984/25/41/415702 (DOI)000324920400016 ()2-s2.0-84884851147 (Scopus ID)
Funder
Knut and Alice Wallenberg FoundationSwedish Research Council
Note

QC 20131025

Available from: 2013-10-25 Created: 2013-10-24 Last updated: 2018-01-12Bibliographically approved
4. Skyrmions induced by dissipationless drag in U(1)xU(1) superconductors
Open this publication in new window or tab >>Skyrmions induced by dissipationless drag in U(1)xU(1) superconductors
2014 (English)In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 89, no 10, p. 104508-Article in journal (Refereed) Published
Abstract [en]

Rather generically, multicomponent superconductors and superfluids have intercomponent current-current interaction. We show that in superconductors with substantially strong intercomponent drag interaction, the topological defects which form in an external field are characterized by a skyrmionic topological charge. We then demonstrate that they can be distinguished from ordinary vortex matter by a very characteristic magnetization process due to the dipolar nature of inter-skyrmion forces. The results provide an experimental signature to confirm or rule out the formation p-wave state with reduced spin stiffness in p-wave superconductors.

Keywords
Lattices, Phases, Upt3
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-143682 (URN)10.1103/PhysRevB.89.104508 (DOI)000332459900006 ()2-s2.0-84897906225 (Scopus ID)
Funder
Swedish Research CouncilKnut and Alice Wallenberg Foundation
Note

QC 20140328

Available from: 2014-03-28 Created: 2014-03-27 Last updated: 2018-01-12Bibliographically approved
5. Stripe, gossamer, and glassy phases in systems with strong nonpairwise interactions
Open this publication in new window or tab >>Stripe, gossamer, and glassy phases in systems with strong nonpairwise interactions
2013 (English)In: Physical Review E. Statistical, Nonlinear, and Soft Matter Physics, ISSN 1539-3755, E-ISSN 1550-2376, Vol. 88, no 4, p. 042305-Article in journal (Refereed) Published
Abstract [en]

We study structure formation in systems of classical particles in two dimensions with long-range attractive short-range repulsive two-body interactions and repulsive three-body interactions. Stripe, gossamer, and glass phases are found as a result of nonpairwise interaction.

Keywords
Superconductivity, Forces
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-133971 (URN)10.1103/PhysRevE.88.042305 (DOI)000326047800007 ()2-s2.0-84886029788 (Scopus ID)
Funder
Knut and Alice Wallenberg FoundationSwedish Research Council
Note

QC 20131115

Available from: 2013-11-15 Created: 2013-11-14 Last updated: 2018-01-12Bibliographically approved

Open Access in DiVA

thesis(8396 kB)103 downloads
File information
File name FULLTEXT01.pdfFile size 8396 kBChecksum SHA-512
a752a1fc3dd8b0aac4c8f1778c2ee3139767fb87b1301bef34b10f8b6d99dcd801c6e29ba4a79645f6d9db8c99d7ae77f738e41231c20def6fb5cb5edd4cacb9
Type fulltextMimetype application/pdf

Search in DiVA

By author/editor
Sellin, Karl
By organisation
Statistical Physics
Condensed Matter Physics

Search outside of DiVA

GoogleGoogle Scholar
Total: 103 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

isbn
urn-nbn

Altmetric score

isbn
urn-nbn
Total: 895 hits
CiteExportLink to record
Permanent link

Direct 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