Disorder, low-energy excitations, and topology in the Kitaev spin-liquid
Autor(a) principal: | |
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Data de Publicação: | 2022 |
Tipo de documento: | Dissertação |
Idioma: | eng |
Título da fonte: | Biblioteca Digital de Teses e Dissertações da USP |
Texto Completo: | https://doi.org/10.11606/D.76.2022.tde-18082022-085608 |
Resumo: | Frustrated magnetism is a very active research topic in condensed matter physics. The competition between different ground states often leads to a suppression of the ordering temperature and opens up the possibility that novel states emerge. One state of particular interest are the spin liquids, for which we find no broken symmetry down to T —› 0, where T is the temperature. Moreover, theses states show topological order and are notable for their peculiar features, such as long-range entanglement and the emergence of fractionalized excitations. The Kitaev model is a fascinating example of an exactly solvable model displaying a spin-liquid ground state in two dimensions. In real materials, however, deviations from the original Kitaev model are expected to appear, and we discuss relevant perturbations here. In this work, we investigate the fate of Kitaevs spin-liquid in the presence of disorder bond defects or vacancies for an extended version of the model. Considering static flux backgrounds, we observe a power-law divergence in the low-energy limit of the density of states, with a non-universal exponent. We link this power-law distribution of energy scales to weakly coupled droplets inside the bulk, in an uncanny similarity to the Griffiths phase often present in the vicinity of disordered quantum phase transitions. If time-reversal symmetry is broken, we find that power-law singularities are tied to the destruction of the topological phase of the Kitaev model in the presence of bond disorder alone. For weak to moderate site dilution, there is a transition from this topologically trivial phase with power-law singularities to a topologically non-trivial one. Therefore, diluted Kitaev materials are potential candidates to host Kitaevs chiral spin-liquid phase. |
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info:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/masterThesis Disorder, low-energy excitations, and topology in the Kitaev spin-liquid Desordem, excitações de baixas energias, e topologia no líquido de spin de Kitaev. 2022-05-31Eric de Castro e AndradeNatanael de Carvalho CostaEduardo MirandaVítor Dantas MeirelesUniversidade de São PauloFísicaUSPBR Fases de Griffiths Fases topológicas Frustrated magnetism Griffiths phase Kitaev model Líquidos de spin quânticos Magnetismo frustrado Modelo de Kitaev Quantum spin liquids Topological phases Frustrated magnetism is a very active research topic in condensed matter physics. The competition between different ground states often leads to a suppression of the ordering temperature and opens up the possibility that novel states emerge. One state of particular interest are the spin liquids, for which we find no broken symmetry down to T —› 0, where T is the temperature. Moreover, theses states show topological order and are notable for their peculiar features, such as long-range entanglement and the emergence of fractionalized excitations. The Kitaev model is a fascinating example of an exactly solvable model displaying a spin-liquid ground state in two dimensions. In real materials, however, deviations from the original Kitaev model are expected to appear, and we discuss relevant perturbations here. In this work, we investigate the fate of Kitaevs spin-liquid in the presence of disorder bond defects or vacancies for an extended version of the model. Considering static flux backgrounds, we observe a power-law divergence in the low-energy limit of the density of states, with a non-universal exponent. We link this power-law distribution of energy scales to weakly coupled droplets inside the bulk, in an uncanny similarity to the Griffiths phase often present in the vicinity of disordered quantum phase transitions. If time-reversal symmetry is broken, we find that power-law singularities are tied to the destruction of the topological phase of the Kitaev model in the presence of bond disorder alone. For weak to moderate site dilution, there is a transition from this topologically trivial phase with power-law singularities to a topologically non-trivial one. Therefore, diluted Kitaev materials are potential candidates to host Kitaevs chiral spin-liquid phase. Magnetismo frustrado é um tópico de pesquisa muito ativo em física da matéria condensada. A competição entre diferentes estados fundamentais muitas vezes leva a uma supressão da temperatura de ordenamento e abre a possibilidade para a emergência de novos estados da matéria. Um estado de particular interesse são os líquidos de spin, para os quais não encontramos quebra de simetria em T —› 0, onde T é a temperatura. Além disso, esses estados apresentam ordem topológica e são notáveis por suas características peculiares, como o emaranhamento de longo alcance e o surgimento de excitações fracionalizadas. O modelo Kitaev é um exemplo fascinante de um modelo exatamente solúvel que exibe um estado fundamental de líquido de spin em duas dimensões. Em materiais reais, no entanto, espera-se que surjam desvios do modelo original de Kitaev. Neste trabalho, investigamos o destino do líquido de spin de Kitaev na presença de desordem defeitos nas ligações ou vacâncias para uma versão estendida do modelo. Considerando configurações de fluxo estáticas, observamos uma divergência do tipo lei de potência no limite de baixas energias da densidade de estados, com um expoente não universal. Associamos essa distribuição da lei de potência nas escalas de energia à regiões fracamente acopladas dentro do sistema, em uma surpreendente semelhança com a fase de Griffiths, frequentemente encontrada nas redondezas de transições de fase quânticas desordenadas. No caso em que a simetria de reversão temporal é quebrada, descobrimos que as singularidades do tipo lei de potência estão ligadas à destruição da fase topológica do modelo de Kitaev, na presença de desordem nas ligações apenas. Para uma diluição de sítios fraca a moderada, há uma transição desta fase topologicamente trivial com singularidades de lei de potência para uma fase topologicamente não trivial. Portanto, materiais de Kitaev diluídos são potenciais candidatos para hospedar a fase de líquido de spin quiral de Kitaev. https://doi.org/10.11606/D.76.2022.tde-18082022-085608info:eu-repo/semantics/openAccessengreponame:Biblioteca Digital de Teses e Dissertações da USPinstname:Universidade de São Paulo (USP)instacron:USP2023-12-21T19:19:14Zoai:teses.usp.br:tde-18082022-085608Biblioteca Digital de Teses e Dissertaçõeshttp://www.teses.usp.br/PUBhttp://www.teses.usp.br/cgi-bin/mtd2br.plvirginia@if.usp.br|| atendimento@aguia.usp.br||virginia@if.usp.bropendoar:27212023-12-22T12:52:00.761638Biblioteca Digital de Teses e Dissertações da USP - Universidade de São Paulo (USP)false |
dc.title.en.fl_str_mv |
Disorder, low-energy excitations, and topology in the Kitaev spin-liquid |
dc.title.alternative.pt.fl_str_mv |
Desordem, excitações de baixas energias, e topologia no líquido de spin de Kitaev. |
title |
Disorder, low-energy excitations, and topology in the Kitaev spin-liquid |
spellingShingle |
Disorder, low-energy excitations, and topology in the Kitaev spin-liquid Vítor Dantas Meireles |
title_short |
Disorder, low-energy excitations, and topology in the Kitaev spin-liquid |
title_full |
Disorder, low-energy excitations, and topology in the Kitaev spin-liquid |
title_fullStr |
Disorder, low-energy excitations, and topology in the Kitaev spin-liquid |
title_full_unstemmed |
Disorder, low-energy excitations, and topology in the Kitaev spin-liquid |
title_sort |
Disorder, low-energy excitations, and topology in the Kitaev spin-liquid |
author |
Vítor Dantas Meireles |
author_facet |
Vítor Dantas Meireles |
author_role |
author |
dc.contributor.advisor1.fl_str_mv |
Eric de Castro e Andrade |
dc.contributor.referee1.fl_str_mv |
Natanael de Carvalho Costa |
dc.contributor.referee2.fl_str_mv |
Eduardo Miranda |
dc.contributor.author.fl_str_mv |
Vítor Dantas Meireles |
contributor_str_mv |
Eric de Castro e Andrade Natanael de Carvalho Costa Eduardo Miranda |
description |
Frustrated magnetism is a very active research topic in condensed matter physics. The competition between different ground states often leads to a suppression of the ordering temperature and opens up the possibility that novel states emerge. One state of particular interest are the spin liquids, for which we find no broken symmetry down to T —› 0, where T is the temperature. Moreover, theses states show topological order and are notable for their peculiar features, such as long-range entanglement and the emergence of fractionalized excitations. The Kitaev model is a fascinating example of an exactly solvable model displaying a spin-liquid ground state in two dimensions. In real materials, however, deviations from the original Kitaev model are expected to appear, and we discuss relevant perturbations here. In this work, we investigate the fate of Kitaevs spin-liquid in the presence of disorder bond defects or vacancies for an extended version of the model. Considering static flux backgrounds, we observe a power-law divergence in the low-energy limit of the density of states, with a non-universal exponent. We link this power-law distribution of energy scales to weakly coupled droplets inside the bulk, in an uncanny similarity to the Griffiths phase often present in the vicinity of disordered quantum phase transitions. If time-reversal symmetry is broken, we find that power-law singularities are tied to the destruction of the topological phase of the Kitaev model in the presence of bond disorder alone. For weak to moderate site dilution, there is a transition from this topologically trivial phase with power-law singularities to a topologically non-trivial one. Therefore, diluted Kitaev materials are potential candidates to host Kitaevs chiral spin-liquid phase. |
publishDate |
2022 |
dc.date.issued.fl_str_mv |
2022-05-31 |
dc.type.status.fl_str_mv |
info:eu-repo/semantics/publishedVersion |
dc.type.driver.fl_str_mv |
info:eu-repo/semantics/masterThesis |
format |
masterThesis |
status_str |
publishedVersion |
dc.identifier.uri.fl_str_mv |
https://doi.org/10.11606/D.76.2022.tde-18082022-085608 |
url |
https://doi.org/10.11606/D.76.2022.tde-18082022-085608 |
dc.language.iso.fl_str_mv |
eng |
language |
eng |
dc.rights.driver.fl_str_mv |
info:eu-repo/semantics/openAccess |
eu_rights_str_mv |
openAccess |
dc.publisher.none.fl_str_mv |
Universidade de São Paulo |
dc.publisher.program.fl_str_mv |
Física |
dc.publisher.initials.fl_str_mv |
USP |
dc.publisher.country.fl_str_mv |
BR |
publisher.none.fl_str_mv |
Universidade de São Paulo |
dc.source.none.fl_str_mv |
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USP |
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Biblioteca Digital de Teses e Dissertações da USP |
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Biblioteca Digital de Teses e Dissertações da USP |
repository.name.fl_str_mv |
Biblioteca Digital de Teses e Dissertações da USP - Universidade de São Paulo (USP) |
repository.mail.fl_str_mv |
virginia@if.usp.br|| atendimento@aguia.usp.br||virginia@if.usp.br |
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