Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • 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
Simulations of thermoelectric transport in granularsuperconductors
KTH, School of Engineering Sciences (SCI), Theoretical Physics, Statistical Physics.
2010 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis presents results from numerical simulations of the Nernst effect dueto phase fluctuations in models of two-dimensional granular superconductors. Inaddition other transport properties, such as thermal conductivity and electrical re-sistivity are calculated. The models are based on a phase only description withLangevin or resistively and capacitively shunted Josephson junction (RCSJ) dy-namics, generalized to be valid for any type of two-dimensional lattice structure.All transport coefficients are evaluated from equilibrium correlation functions usingKubo formulas.

In Paper I, anomalous sign reversals of the Nernst signal eN , corresponding tovortex motion from colder to hotter regions, are observed. These are attributedto geometric frustration effects close to magnetic fields commensurate with theunderlying lattice structure. The effect is seen also in systems with moderategeometric disorder, and should thus be possible to observe in real two-dimensionalgranular superconductors or Josephson junction arrays.

Paper II presents two different derivations of an expression for the heat current inLangevin and RCSJ dynamics. The resulting expression is through our simulationsseen to obey the required Onsager relation, as well as giving consistent resultswhen calculating κ and eN via Kubo formulas and through the responses to anapplied temperature gradient. In zero magnetic field and at low-temperatures, thecontribution to the thermal conductivity κ in RCSJ dynamics is calculated usinga spin-wave approximation, and is shown to be independent of temperature anddiverge logarithmically with system size. At higher temperatures, κ shows a non-monotonic temperature dependence. In zero magnetic field κ has a anomalouslogarithmic size dependence also in this regime. The off-diagonal component ofthe thermoelectric tensor αxy is calculated and displays the very same ∼1/T dependence at low temperatures predicted from calculations based on Gaussiansuperconducting fluctuations.

Place, publisher, year, edition, pages
Stockholm: KTH , 2010. , ix, 53 p.
Series
Trita-FYS, ISSN 0280-316X ; 2010:27
National Category
Condensed Matter Physics
Identifiers
URN: urn:nbn:se:kth:diva-12898ISBN: 978-91-7415-659-1 (print)OAI: oai:DiVA.org:kth-12898DiVA: diva2:319610
Presentation
2010-06-09, FD51, AlbaNova, Roslagstullsbacken 21, Stockholm, 10:00 (English)
Opponent
Supervisors
Available from: 2010-06-07 Created: 2010-05-18 Last updated: 2010-06-07Bibliographically approved

Open Access in DiVA

fulltext(860 kB)509 downloads
File information
File name FULLTEXT02.pdfFile size 860 kBChecksum SHA-512
f1d1d2206d94aded43e65278331a9b455ac15318a6e1d4742fc53709f1bfc8fbcd33a67e5eec87c48116762ab87f3d819d04b0a1cf642aa6d80d842eb2fc9160
Type fulltextMimetype application/pdf

Search in DiVA

By author/editor
Andersson, Andreas
By organisation
Statistical Physics
Condensed Matter Physics

Search outside of DiVA

GoogleGoogle Scholar
Total: 509 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: 231 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • 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