Aspects of multigap and multilayer superconductivity
Autor(a) principal: | |
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Data de Publicação: | 2017 |
Tipo de documento: | Tese |
Idioma: | eng |
Título da fonte: | Repositório Institucional da Universidade Federal Fluminense (RIUFF) |
Texto Completo: | https://app.uff.br/riuff/handle/1/6193 |
Resumo: | This dissertation is composed of two parts. The first part was developed at Universidade Federal Fluminense (UFF) under the supervision of Prof. Dr. Evandro Vidor Lins de Mello and addresses the temperature dependence of the superconducting gaps in ironbased superconductors. The second part was developed at the Eidgenössische Technische Hochschule Zürich (ETH) during a visiting year under the supervision of Prof. Dr. Manfred Sigrist. This part concerns the effect of vortices on the superconducting properties of a three-layer system. The following paragraph is the abstract of part one. The last paragraph is the abstract of part two. The temperature dependence of the multiple superconducting gaps in the typical high-Tc iron-based superconductor Ba0.6K0.4Fe2As2 is studied. These multiband ironbased superconductors display multiple superconducting gaps with different coupling ratios 2Δ0/kBTc, but a single Tc. The guiding question throughout this project is: is it possible to reproduce the various coupling ratios and single Tc observed in Fe-based superconductors within a weak-coupling Bogoliubov-deGennes theory? This dissertation proposes two distinct mechanisms through which it is possible to reproduce the temperature dependence of the multigap structure of Ba0.6K0.4Fe2As2. The first proposal shows how intrinsic charge inhomogeneity might lead to a temperature dependent Cooper pairing potential. The second proposal uses arguments from inhomogeneous superconductivity applied to multiband superconductors to introduce a temperature dependent chemical potential. In part two, we investigate the pair-density wave phase of multilayer superconductors in the context of a Ginzburg-Landau theory. In multilayer systems, due to local inversion symmetry breaking at the outer layers, a Rashba spin-orbit coupling is induced. This combined with a perpendicular Pauli limiting magnetic field stabilizes a pair-density wave (PDW) phase, which is achieved through a first-order phase transition. The PDW phase is robust against magnetic fields. The central issue discussed in this dissertation is whether orbital limiting (on top of dominant paramagnetic limiting) destroys the PDW phase. We find that orbital limiting does not destroy the the PDW phase and investigate the behavior of a single vortex core through the first-order BCS-PDW phase transition. As a subproject, we also study the paramagnetic effect on the reversible magnetization curves of high-κ type II superconductors by generalizing a circular cell method within a Ginzburg-Landau theory. |
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Aspects of multigap and multilayer superconductivitySupercondutividadeMagnetismoTeoria de Ginzburg-LandauSuper-redeThis dissertation is composed of two parts. The first part was developed at Universidade Federal Fluminense (UFF) under the supervision of Prof. Dr. Evandro Vidor Lins de Mello and addresses the temperature dependence of the superconducting gaps in ironbased superconductors. The second part was developed at the Eidgenössische Technische Hochschule Zürich (ETH) during a visiting year under the supervision of Prof. Dr. Manfred Sigrist. This part concerns the effect of vortices on the superconducting properties of a three-layer system. The following paragraph is the abstract of part one. The last paragraph is the abstract of part two. The temperature dependence of the multiple superconducting gaps in the typical high-Tc iron-based superconductor Ba0.6K0.4Fe2As2 is studied. These multiband ironbased superconductors display multiple superconducting gaps with different coupling ratios 2Δ0/kBTc, but a single Tc. The guiding question throughout this project is: is it possible to reproduce the various coupling ratios and single Tc observed in Fe-based superconductors within a weak-coupling Bogoliubov-deGennes theory? This dissertation proposes two distinct mechanisms through which it is possible to reproduce the temperature dependence of the multigap structure of Ba0.6K0.4Fe2As2. The first proposal shows how intrinsic charge inhomogeneity might lead to a temperature dependent Cooper pairing potential. The second proposal uses arguments from inhomogeneous superconductivity applied to multiband superconductors to introduce a temperature dependent chemical potential. In part two, we investigate the pair-density wave phase of multilayer superconductors in the context of a Ginzburg-Landau theory. In multilayer systems, due to local inversion symmetry breaking at the outer layers, a Rashba spin-orbit coupling is induced. This combined with a perpendicular Pauli limiting magnetic field stabilizes a pair-density wave (PDW) phase, which is achieved through a first-order phase transition. The PDW phase is robust against magnetic fields. The central issue discussed in this dissertation is whether orbital limiting (on top of dominant paramagnetic limiting) destroys the PDW phase. We find that orbital limiting does not destroy the the PDW phase and investigate the behavior of a single vortex core through the first-order BCS-PDW phase transition. As a subproject, we also study the paramagnetic effect on the reversible magnetization curves of high-κ type II superconductors by generalizing a circular cell method within a Ginzburg-Landau theory.Conselho Nacional de Desenvolvimento Científico e TecnológicoEsta tese é composta por duas partes. A primeira foi desenvolvida na Universidade Federal Fluminense (UFF) sob orientação do Prof. Dr. Evandro Vidor Lins de Mello. Neste projeto, estudamos como os gaps supercondutores variam com a temperatura em supercondutores a base de ferro. A parte dois desta tese foi desenvolvida na Eidgenössische Technische Hochschule Zürich (ETH) durante um estágio sanduíche supervisionado pelo Prof. Dr. Manfred Sigrist. Nesta parte estudamos o efeito de vórtices sobre as propriedades supercondutoras de um sistema de três camadas. O seguinte parágrafo corresponde ao resumo da parte um, e o último parágrafo a parte dois. Aqui estudamos como os múltiplos gaps supercondutores variam com a temperatura no supercondutor a base de ferro Ba0.6K0.4Fe2As2. Estes materiais multibanda possuem múltiplos gaps com acoplamentos 2Δ0/kBTc distintos, mas apresentam uma única temperatura crítica de transição Tc. A pergunta guia deste projeto é: é possível reproduzir os diferentes acoplamentos e único Tc presente em supercondutores a base de ferro, dentro do contexto de uma teoria de Bogoliubov-deGennes de acoplamento fraco? Nesta tese apresentamos dois mecanismos que permite reproduzir os gaps de Ba0.6K0.4Fe2As2. A primeira proposta mostra como uma inomogeneidade intrínseca destes materiais pode levar a um potencial de pareamento dependente da temperatura. A segunda proposta usa argumentos da supercondutividade inomogênea aplicada a supercondutores multibanda para introduzir um potencial químico dependente da temperatura. Na parte dois, investigamos a fase PDW (pair-density wave) em supercondutores multicamada no contexto de uma teoria de Ginzburg-Landau. Nestes sistemas, uma interação spin-órbita do tipo Rashba é induzida devido a quebra local de simetria de inversão nas camadas externas. Isto combinado com um campo magnético perpendicular externo estabiliza a fase PDW, que é obtida através de uma transição de fase de primeira ordem. A fase PDW é robusta contra a ação de campos magnéticos. A questão central discutida nesta tese é se a penetração de vórtices destrói a fase PDW. Como um subprojeto, nós também obtivemos as curvas de magnetização reversíveis para supercondutores do tipo-II com κ grande. Para isto, generalizamos um método de aproximação circular dentro do contexto da teoria de Ginzurg-Landau.NiteróiMello, Evandro Vidor Lins deSigrist, ManfredMöckli, David2018-04-11T16:49:34Z2018-04-11T16:49:34Z2017info:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/doctoralThesisapplication/pdfhttps://app.uff.br/riuff/handle/1/6193Aluno de doutoradoopenAccesshttp://creativecommons.org/licenses/by-nc-nd/3.0/br/CC-BY-SAinfo:eu-repo/semantics/openAccessengreponame:Repositório Institucional da Universidade Federal Fluminense (RIUFF)instname:Universidade Federal Fluminense (UFF)instacron:UFF2020-07-27T17:11:51Zoai:app.uff.br:1/6193Repositório InstitucionalPUBhttps://app.uff.br/oai/requestriuff@id.uff.bropendoar:21202024-08-19T10:52:49.778134Repositório Institucional da Universidade Federal Fluminense (RIUFF) - Universidade Federal Fluminense (UFF)false |
dc.title.none.fl_str_mv |
Aspects of multigap and multilayer superconductivity |
title |
Aspects of multigap and multilayer superconductivity |
spellingShingle |
Aspects of multigap and multilayer superconductivity Möckli, David Supercondutividade Magnetismo Teoria de Ginzburg-Landau Super-rede |
title_short |
Aspects of multigap and multilayer superconductivity |
title_full |
Aspects of multigap and multilayer superconductivity |
title_fullStr |
Aspects of multigap and multilayer superconductivity |
title_full_unstemmed |
Aspects of multigap and multilayer superconductivity |
title_sort |
Aspects of multigap and multilayer superconductivity |
author |
Möckli, David |
author_facet |
Möckli, David |
author_role |
author |
dc.contributor.none.fl_str_mv |
Mello, Evandro Vidor Lins de Sigrist, Manfred |
dc.contributor.author.fl_str_mv |
Möckli, David |
dc.subject.por.fl_str_mv |
Supercondutividade Magnetismo Teoria de Ginzburg-Landau Super-rede |
topic |
Supercondutividade Magnetismo Teoria de Ginzburg-Landau Super-rede |
description |
This dissertation is composed of two parts. The first part was developed at Universidade Federal Fluminense (UFF) under the supervision of Prof. Dr. Evandro Vidor Lins de Mello and addresses the temperature dependence of the superconducting gaps in ironbased superconductors. The second part was developed at the Eidgenössische Technische Hochschule Zürich (ETH) during a visiting year under the supervision of Prof. Dr. Manfred Sigrist. This part concerns the effect of vortices on the superconducting properties of a three-layer system. The following paragraph is the abstract of part one. The last paragraph is the abstract of part two. The temperature dependence of the multiple superconducting gaps in the typical high-Tc iron-based superconductor Ba0.6K0.4Fe2As2 is studied. These multiband ironbased superconductors display multiple superconducting gaps with different coupling ratios 2Δ0/kBTc, but a single Tc. The guiding question throughout this project is: is it possible to reproduce the various coupling ratios and single Tc observed in Fe-based superconductors within a weak-coupling Bogoliubov-deGennes theory? This dissertation proposes two distinct mechanisms through which it is possible to reproduce the temperature dependence of the multigap structure of Ba0.6K0.4Fe2As2. The first proposal shows how intrinsic charge inhomogeneity might lead to a temperature dependent Cooper pairing potential. The second proposal uses arguments from inhomogeneous superconductivity applied to multiband superconductors to introduce a temperature dependent chemical potential. In part two, we investigate the pair-density wave phase of multilayer superconductors in the context of a Ginzburg-Landau theory. In multilayer systems, due to local inversion symmetry breaking at the outer layers, a Rashba spin-orbit coupling is induced. This combined with a perpendicular Pauli limiting magnetic field stabilizes a pair-density wave (PDW) phase, which is achieved through a first-order phase transition. The PDW phase is robust against magnetic fields. The central issue discussed in this dissertation is whether orbital limiting (on top of dominant paramagnetic limiting) destroys the PDW phase. We find that orbital limiting does not destroy the the PDW phase and investigate the behavior of a single vortex core through the first-order BCS-PDW phase transition. As a subproject, we also study the paramagnetic effect on the reversible magnetization curves of high-κ type II superconductors by generalizing a circular cell method within a Ginzburg-Landau theory. |
publishDate |
2017 |
dc.date.none.fl_str_mv |
2017 2018-04-11T16:49:34Z 2018-04-11T16:49:34Z |
dc.type.status.fl_str_mv |
info:eu-repo/semantics/publishedVersion |
dc.type.driver.fl_str_mv |
info:eu-repo/semantics/doctoralThesis |
format |
doctoralThesis |
status_str |
publishedVersion |
dc.identifier.uri.fl_str_mv |
https://app.uff.br/riuff/handle/1/6193 Aluno de doutorado |
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https://app.uff.br/riuff/handle/1/6193 |
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Aluno de doutorado |
dc.language.iso.fl_str_mv |
eng |
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eng |
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openAccess http://creativecommons.org/licenses/by-nc-nd/3.0/br/ CC-BY-SA info:eu-repo/semantics/openAccess |
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openAccess http://creativecommons.org/licenses/by-nc-nd/3.0/br/ CC-BY-SA |
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openAccess |
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application/pdf |
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Niterói |
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Niterói |
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reponame:Repositório Institucional da Universidade Federal Fluminense (RIUFF) instname:Universidade Federal Fluminense (UFF) instacron:UFF |
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Universidade Federal Fluminense (UFF) |
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UFF |
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UFF |
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Repositório Institucional da Universidade Federal Fluminense (RIUFF) |
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Repositório Institucional da Universidade Federal Fluminense (RIUFF) |
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Repositório Institucional da Universidade Federal Fluminense (RIUFF) - Universidade Federal Fluminense (UFF) |
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riuff@id.uff.br |
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