Modelo de Heisenberg com campo aleatório e interação Dzyaloshinskii-Moriya
Autor(a) principal: | |
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Data de Publicação: | 2018 |
Tipo de documento: | Dissertação |
Idioma: | por |
Título da fonte: | Repositório Institucional da UFS |
Texto Completo: | http://ri.ufs.br/jspui/handle/riufs/10739 |
Resumo: | The critical behavior of systems that exhibit magnetism has been the subject of intense research. The Heisenberg model deserves special attention because it is a tool to be used to describe the properties of many magnetic, insulators and anisotropic materials. In addition, it is known that the consideration of anisotropic effects in many spin models can result in the presence of tricritical behavior in the phase diagram and thermodynamic properties. In particular, the Dzyaloshinskii-Moriya (DM) interaction consists of an important type of anisotropy, which since the last decades has attracted a great deal of attention, playing an important role in the description of some classes of insulators, as well as in the study of the phenomena involving spin-glass, among others. The presence of disorder in the models, introduced by random variables governed by a given probability distribution, also usually results in the alteration of the critical behavior in relation to the homogeneous system. Therefore, the interest in the systems in the presence of random field has grown. With such motivation, the spin-1/2 and spin-1 anisotropic Heisenberg models with DM interaction and magnetic random field are studied within the framework of Oguchi’s pair approximation. Although the approach is developed for lattices with general coordination number z the model is discussed in detail for the simple cubic lattice (z = 6). The critical behavior dependent on both the DM parameter and the random field is analyzed. The investigation of phase diagrams reveals the presence of tricritical points and the results are extended to describe the behavior of the thermodynamic properties of the system. |
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Silva, Joeliton Barros daAlbuquerque, Douglas Ferreira de2019-03-21T22:04:17Z2019-03-21T22:04:17Z2018-12-20SILVA, Joeliton Barros da. Modelo de Heisenberg com campo aleatório e interação Dzyaloshinskii-Moriya. 2018. 75 f. Dissertação (Mestrado em Física) - Universidade Federal de Sergipe, São Cristóvão, SE, 2018.http://ri.ufs.br/jspui/handle/riufs/10739The critical behavior of systems that exhibit magnetism has been the subject of intense research. The Heisenberg model deserves special attention because it is a tool to be used to describe the properties of many magnetic, insulators and anisotropic materials. In addition, it is known that the consideration of anisotropic effects in many spin models can result in the presence of tricritical behavior in the phase diagram and thermodynamic properties. In particular, the Dzyaloshinskii-Moriya (DM) interaction consists of an important type of anisotropy, which since the last decades has attracted a great deal of attention, playing an important role in the description of some classes of insulators, as well as in the study of the phenomena involving spin-glass, among others. The presence of disorder in the models, introduced by random variables governed by a given probability distribution, also usually results in the alteration of the critical behavior in relation to the homogeneous system. Therefore, the interest in the systems in the presence of random field has grown. With such motivation, the spin-1/2 and spin-1 anisotropic Heisenberg models with DM interaction and magnetic random field are studied within the framework of Oguchi’s pair approximation. Although the approach is developed for lattices with general coordination number z the model is discussed in detail for the simple cubic lattice (z = 6). The critical behavior dependent on both the DM parameter and the random field is analyzed. The investigation of phase diagrams reveals the presence of tricritical points and the results are extended to describe the behavior of the thermodynamic properties of the system.O comportamento crítico de sistemas que exibem magnetismo tem sido objeto de intensa pesquisa. O modelo de Heisenberg merece especial atenção por se tratar de uma ferramenta a ser empregada para a descrição das propriedades de muitos materiais magnéticos, isolantes e anisotrópicos. Além disso, sabe-se que a consideração de efeitos anisotrópicos em muitos modelos de spins pode resultar na presença de comportamento tricrítico no diagrama de fases e propriedades termodinâmicas. Em particular, a interação Dzyaloshinskii-Moriya (DM) consiste em um importante tipo de anisotropia, que desde as últimas décadas tem atraído muita atenção, desempenhando um papel relevante na descrição de algumas classes de isolantes, bem como no estudo dos fenômenos envolvendo vidro de spin, dentre outros. A presença de desordem nos modelos, introduzida através de variáveis aleatórias governadas por uma dada distribuição de probabilidades, também resulta geralmente na alteração do comportamento crítico em relação ao sistema homogêneo, de modo que tem crescido o interesse nos sistemas em presença de campo aleatório. Com tal motivação, o modelo de Heisenberg anisotrópico com interação DM e campo magnético aleatório (com distribuição trimodal) é estudado nas versões spin 1/2 e spin 1 usando o método de Oguchi (aproximação de pares). Embora a abordagem seja desenvolvida para redes com número de coordenação z geral, é tratado em detalhes o modelo na rede cúbica simples, com número de coordenação z = 6. O comportamento crítico, com dependência tanto do parâmetro DM quanto do campo aleatório é analisado. Os diagramas de fases investigados revelam a presença de pontos tricríticos e os resultados são estendidos à descrição do comportamento das propriedades termodinâmicas do sistema.São Cristóvão, SEporModelo de HeisenbergInteração Dzyaloshinskii-MoriyaCampo aleatórioPonto tricríticoHeisenberg modelDzyaloshinskii-Moriya interactionRandom fieldTricritical pointCIENCIAS EXATAS E DA TERRA::FISICAModelo de Heisenberg com campo aleatório e interação Dzyaloshinskii-Moriyainfo:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/masterThesisPós-Graduação em FísicaUFSreponame:Repositório Institucional da UFSinstname:Universidade Federal de Sergipe (UFS)instacron:UFSinfo:eu-repo/semantics/openAccessTEXTJOELITON_BARROS_SILVA.pdf.txtJOELITON_BARROS_SILVA.pdf.txtExtracted texttext/plain139229https://ri.ufs.br/jspui/bitstream/riufs/10739/3/JOELITON_BARROS_SILVA.pdf.txtb3f017b5aeec04f315224f68056c3a37MD53THUMBNAILJOELITON_BARROS_SILVA.pdf.jpgJOELITON_BARROS_SILVA.pdf.jpgGenerated Thumbnailimage/jpeg1315https://ri.ufs.br/jspui/bitstream/riufs/10739/4/JOELITON_BARROS_SILVA.pdf.jpg176c703f7993d871c8c99b49db624b90MD54LICENSElicense.txtlicense.txttext/plain; charset=utf-81475https://ri.ufs.br/jspui/bitstream/riufs/10739/1/license.txt098cbbf65c2c15e1fb2e49c5d306a44cMD51ORIGINALJOELITON_BARROS_SILVA.pdfJOELITON_BARROS_SILVA.pdfapplication/pdf5164401https://ri.ufs.br/jspui/bitstream/riufs/10739/2/JOELITON_BARROS_SILVA.pdf513d4322d3a37446f8fe7ef66fd8f2f5MD52riufs/107392019-03-21 19:04:17.815oai:ufs.br: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Repositório InstitucionalPUBhttps://ri.ufs.br/oai/requestrepositorio@academico.ufs.bropendoar:2019-03-21T22:04:17Repositório Institucional da UFS - Universidade Federal de Sergipe (UFS)false |
dc.title.pt_BR.fl_str_mv |
Modelo de Heisenberg com campo aleatório e interação Dzyaloshinskii-Moriya |
title |
Modelo de Heisenberg com campo aleatório e interação Dzyaloshinskii-Moriya |
spellingShingle |
Modelo de Heisenberg com campo aleatório e interação Dzyaloshinskii-Moriya Silva, Joeliton Barros da Modelo de Heisenberg Interação Dzyaloshinskii-Moriya Campo aleatório Ponto tricrítico Heisenberg model Dzyaloshinskii-Moriya interaction Random field Tricritical point CIENCIAS EXATAS E DA TERRA::FISICA |
title_short |
Modelo de Heisenberg com campo aleatório e interação Dzyaloshinskii-Moriya |
title_full |
Modelo de Heisenberg com campo aleatório e interação Dzyaloshinskii-Moriya |
title_fullStr |
Modelo de Heisenberg com campo aleatório e interação Dzyaloshinskii-Moriya |
title_full_unstemmed |
Modelo de Heisenberg com campo aleatório e interação Dzyaloshinskii-Moriya |
title_sort |
Modelo de Heisenberg com campo aleatório e interação Dzyaloshinskii-Moriya |
author |
Silva, Joeliton Barros da |
author_facet |
Silva, Joeliton Barros da |
author_role |
author |
dc.contributor.author.fl_str_mv |
Silva, Joeliton Barros da |
dc.contributor.advisor1.fl_str_mv |
Albuquerque, Douglas Ferreira de |
contributor_str_mv |
Albuquerque, Douglas Ferreira de |
dc.subject.por.fl_str_mv |
Modelo de Heisenberg Interação Dzyaloshinskii-Moriya Campo aleatório Ponto tricrítico |
topic |
Modelo de Heisenberg Interação Dzyaloshinskii-Moriya Campo aleatório Ponto tricrítico Heisenberg model Dzyaloshinskii-Moriya interaction Random field Tricritical point CIENCIAS EXATAS E DA TERRA::FISICA |
dc.subject.eng.fl_str_mv |
Heisenberg model Dzyaloshinskii-Moriya interaction Random field Tricritical point |
dc.subject.cnpq.fl_str_mv |
CIENCIAS EXATAS E DA TERRA::FISICA |
description |
The critical behavior of systems that exhibit magnetism has been the subject of intense research. The Heisenberg model deserves special attention because it is a tool to be used to describe the properties of many magnetic, insulators and anisotropic materials. In addition, it is known that the consideration of anisotropic effects in many spin models can result in the presence of tricritical behavior in the phase diagram and thermodynamic properties. In particular, the Dzyaloshinskii-Moriya (DM) interaction consists of an important type of anisotropy, which since the last decades has attracted a great deal of attention, playing an important role in the description of some classes of insulators, as well as in the study of the phenomena involving spin-glass, among others. The presence of disorder in the models, introduced by random variables governed by a given probability distribution, also usually results in the alteration of the critical behavior in relation to the homogeneous system. Therefore, the interest in the systems in the presence of random field has grown. With such motivation, the spin-1/2 and spin-1 anisotropic Heisenberg models with DM interaction and magnetic random field are studied within the framework of Oguchi’s pair approximation. Although the approach is developed for lattices with general coordination number z the model is discussed in detail for the simple cubic lattice (z = 6). The critical behavior dependent on both the DM parameter and the random field is analyzed. The investigation of phase diagrams reveals the presence of tricritical points and the results are extended to describe the behavior of the thermodynamic properties of the system. |
publishDate |
2018 |
dc.date.issued.fl_str_mv |
2018-12-20 |
dc.date.accessioned.fl_str_mv |
2019-03-21T22:04:17Z |
dc.date.available.fl_str_mv |
2019-03-21T22:04:17Z |
dc.type.status.fl_str_mv |
info:eu-repo/semantics/publishedVersion |
dc.type.driver.fl_str_mv |
info:eu-repo/semantics/masterThesis |
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masterThesis |
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publishedVersion |
dc.identifier.citation.fl_str_mv |
SILVA, Joeliton Barros da. Modelo de Heisenberg com campo aleatório e interação Dzyaloshinskii-Moriya. 2018. 75 f. Dissertação (Mestrado em Física) - Universidade Federal de Sergipe, São Cristóvão, SE, 2018. |
dc.identifier.uri.fl_str_mv |
http://ri.ufs.br/jspui/handle/riufs/10739 |
identifier_str_mv |
SILVA, Joeliton Barros da. Modelo de Heisenberg com campo aleatório e interação Dzyaloshinskii-Moriya. 2018. 75 f. Dissertação (Mestrado em Física) - Universidade Federal de Sergipe, São Cristóvão, SE, 2018. |
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UFS |
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