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Hierarchical structure foramtion in layered superconducting systems with multi-scale inter-vortex interactions
KTH, School of Engineering Sciences (SCI), Theoretical Physics, Statistical Physics.
Show others and affiliations
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.

Place, publisher, year, edition, pages
2013. Vol. 25, no 41, p. 415702-
Keywords [en]
Vortices
National Category
Other Physics Topics
Identifiers
URN: urn:nbn:se:kth:diva-132201DOI: 10.1088/0953-8984/25/41/415702ISI: 000324920400016Scopus ID: 2-s2.0-84884851147OAI: oai:DiVA.org:kth-132201DiVA, id: diva2:659347
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
In thesis
1. Phase transitions and vortex structures in multicomponent superconductors
Open this publication in new window or tab >>Phase transitions and vortex structures in multicomponent superconductors
2015 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Theoretical aspects of multicomponent superconductivity and systemswith competing interactions are studied using Monte Carlo techniques.Motivated by recent experimental and theoretical results of complex struc-ture formation of vortices in multicomponent systems, possible vortex struc-ture formations due to vortex interactions that are not purely attractive orrepulsive are considered. Vortex structures such as clusters, superclusters,hierarchical structure formation, stripes, gossamer patters, glassy phases, aswell as checkerboard lattices and loops are demonstrated to be possible.The order of the superconducting phase transition is considered for multi-component lattice London superconductors. The phase transition is demon-strated to be either rst-order or continuous depending on the strength of asymmetry-breaking Josephson intercomponent interaction. It is argued thatthe rst-order phase transition is caused by a vortex phase separation due toa uctuation-induced attractive interaction between vortex lines.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2015. p. 41
Series
TRITA-FYS, ISSN 0280-316X ; 2015:78
Keywords
multicomponent superconductors, superconductivity, phase transitions, monte carlo, vortices, vortex structure formation, competing interactions
National Category
Condensed Matter Physics Physical Sciences
Identifiers
urn:nbn:se:kth:diva-177141 (URN)978-91-7595-758-6 (ISBN)
Presentation
2015-12-07, FB42, AlbaNova universitetscentrum, Roslagstullsbacken 21, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

QC 20151117

Available from: 2015-11-17 Created: 2015-11-16 Last updated: 2015-11-17Bibliographically approved
2. Structure formation, phase transitions and drag interactions in multicomponent superconductors and superfluids
Open this publication in new window or tab >>Structure formation, phase transitions and drag interactions in multicomponent superconductors and superfluids
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:nbn:se:kth:diva-221081 (URN)978-91-7729-657-7 (ISBN)
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

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