Specific heat and nonlinear susceptibility in spin glasses with random fields
Autor(a) principal: | |
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Data de Publicação: | 2019 |
Outros Autores: | , , |
Tipo de documento: | Artigo |
Idioma: | eng |
Título da fonte: | Repositório Institucional da UFRGS |
Texto Completo: | http://hdl.handle.net/10183/198633 |
Resumo: | We study magnetic properties of spin glass (SG) systems under a random field (RF), based on the suggestion that RFs can be induced by a weak transverse field in the compound LiHo x Y 1 − x F 4 .Weconsideracluster spin model that allows long-range disordered interactions among clusters and short-range interactions inside the clusters, besides a local RF for each spin following a Gaussian distribution with standard deviation Δ. We adopt the one-step replica symmetry breaking approach to get an exactly solvable single-cluster problem. We discuss the behavior of order parameters, specific heat C m , nonlinear susceptibility χ 3 , and phase diagrams for different disorder configurations. In the absence of RF, the χ 3 exhibits a divergence at T f , while the C m shows a broad maximum at a temperature T** around 30% above T f , as expected for conventional SG systems. The presence of RF changes this scenario. The C m still shows the maximum at T** that is weakly dependent on Δ. However,the T f is displaced to lower temperatures, enhancing considerably the ratio T** /T f . Furthermore, the divergence in χ 3 is replaced by a rounded maximum at a temperature T*, which becomes increasingly higher than T f as Δ is enhanced. As a consequence, the paramagnetic phase is unfolded in three regions: (i) a conventional paramagnetism ( T>T** ); (ii) a region with formation of short-range order with frozen spins ( T*<T <T** ); (iii) a region with slow growth of free-energy barriers slowing down the spin dynamics before the SG transition ( T f <T <T* ) suggesting an intermediate Griffiths phase before the SG state. Our results reproduce qualitatively some findings of LiHo x Y 1 − x F 4 as the rounded maximum of χ 3 behavior triggered by RF and the deviation of the conventional relationship between the T f and T**. |
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Romitti, Marcos ViniciosZimmer, Fábio MallmannMorais Junior, Carlos Alberto Vaz deMagalhaes, Sergio Garcia2019-08-29T02:35:26Z20191098-0121http://hdl.handle.net/10183/198633001097228We study magnetic properties of spin glass (SG) systems under a random field (RF), based on the suggestion that RFs can be induced by a weak transverse field in the compound LiHo x Y 1 − x F 4 .Weconsideracluster spin model that allows long-range disordered interactions among clusters and short-range interactions inside the clusters, besides a local RF for each spin following a Gaussian distribution with standard deviation Δ. We adopt the one-step replica symmetry breaking approach to get an exactly solvable single-cluster problem. We discuss the behavior of order parameters, specific heat C m , nonlinear susceptibility χ 3 , and phase diagrams for different disorder configurations. In the absence of RF, the χ 3 exhibits a divergence at T f , while the C m shows a broad maximum at a temperature T** around 30% above T f , as expected for conventional SG systems. The presence of RF changes this scenario. The C m still shows the maximum at T** that is weakly dependent on Δ. However,the T f is displaced to lower temperatures, enhancing considerably the ratio T** /T f . Furthermore, the divergence in χ 3 is replaced by a rounded maximum at a temperature T*, which becomes increasingly higher than T f as Δ is enhanced. As a consequence, the paramagnetic phase is unfolded in three regions: (i) a conventional paramagnetism ( T>T** ); (ii) a region with formation of short-range order with frozen spins ( T*<T <T** ); (iii) a region with slow growth of free-energy barriers slowing down the spin dynamics before the SG transition ( T f <T <T* ) suggesting an intermediate Griffiths phase before the SG state. Our results reproduce qualitatively some findings of LiHo x Y 1 − x F 4 as the rounded maximum of χ 3 behavior triggered by RF and the deviation of the conventional relationship between the T f and T**.application/pdfengPhysical review. B, Condensed matter and materials physics. Woodbury. Vol. 99, no. 1 (Jan. 2019), 014203, 8 p.Vidros de spinSuscetibilidade magnéticaTransformações de faseCampos aleatóriosSpecific heat and nonlinear susceptibility in spin glasses with random fieldsEstrangeiroinfo:eu-repo/semantics/articleinfo:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/openAccessreponame:Repositório Institucional da UFRGSinstname:Universidade Federal do Rio Grande do Sul (UFRGS)instacron:UFRGSTEXT001097228.pdf.txt001097228.pdf.txtExtracted Texttext/plain38909http://www.lume.ufrgs.br/bitstream/10183/198633/2/001097228.pdf.txtf0953f87d7395ccb552be36b3a43fa19MD52ORIGINAL001097228.pdfTexto completo (inglês)application/pdf536033http://www.lume.ufrgs.br/bitstream/10183/198633/1/001097228.pdf94057cf1fa373891d2d05ff9429ae9dbMD5110183/1986332019-08-30 02:35:43.351459oai:www.lume.ufrgs.br:10183/198633Repositório de PublicaçõesPUBhttps://lume.ufrgs.br/oai/requestopendoar:2019-08-30T05:35:43Repositório Institucional da UFRGS - Universidade Federal do Rio Grande do Sul (UFRGS)false |
dc.title.pt_BR.fl_str_mv |
Specific heat and nonlinear susceptibility in spin glasses with random fields |
title |
Specific heat and nonlinear susceptibility in spin glasses with random fields |
spellingShingle |
Specific heat and nonlinear susceptibility in spin glasses with random fields Romitti, Marcos Vinicios Vidros de spin Suscetibilidade magnética Transformações de fase Campos aleatórios |
title_short |
Specific heat and nonlinear susceptibility in spin glasses with random fields |
title_full |
Specific heat and nonlinear susceptibility in spin glasses with random fields |
title_fullStr |
Specific heat and nonlinear susceptibility in spin glasses with random fields |
title_full_unstemmed |
Specific heat and nonlinear susceptibility in spin glasses with random fields |
title_sort |
Specific heat and nonlinear susceptibility in spin glasses with random fields |
author |
Romitti, Marcos Vinicios |
author_facet |
Romitti, Marcos Vinicios Zimmer, Fábio Mallmann Morais Junior, Carlos Alberto Vaz de Magalhaes, Sergio Garcia |
author_role |
author |
author2 |
Zimmer, Fábio Mallmann Morais Junior, Carlos Alberto Vaz de Magalhaes, Sergio Garcia |
author2_role |
author author author |
dc.contributor.author.fl_str_mv |
Romitti, Marcos Vinicios Zimmer, Fábio Mallmann Morais Junior, Carlos Alberto Vaz de Magalhaes, Sergio Garcia |
dc.subject.por.fl_str_mv |
Vidros de spin Suscetibilidade magnética Transformações de fase Campos aleatórios |
topic |
Vidros de spin Suscetibilidade magnética Transformações de fase Campos aleatórios |
description |
We study magnetic properties of spin glass (SG) systems under a random field (RF), based on the suggestion that RFs can be induced by a weak transverse field in the compound LiHo x Y 1 − x F 4 .Weconsideracluster spin model that allows long-range disordered interactions among clusters and short-range interactions inside the clusters, besides a local RF for each spin following a Gaussian distribution with standard deviation Δ. We adopt the one-step replica symmetry breaking approach to get an exactly solvable single-cluster problem. We discuss the behavior of order parameters, specific heat C m , nonlinear susceptibility χ 3 , and phase diagrams for different disorder configurations. In the absence of RF, the χ 3 exhibits a divergence at T f , while the C m shows a broad maximum at a temperature T** around 30% above T f , as expected for conventional SG systems. The presence of RF changes this scenario. The C m still shows the maximum at T** that is weakly dependent on Δ. However,the T f is displaced to lower temperatures, enhancing considerably the ratio T** /T f . Furthermore, the divergence in χ 3 is replaced by a rounded maximum at a temperature T*, which becomes increasingly higher than T f as Δ is enhanced. As a consequence, the paramagnetic phase is unfolded in three regions: (i) a conventional paramagnetism ( T>T** ); (ii) a region with formation of short-range order with frozen spins ( T*<T <T** ); (iii) a region with slow growth of free-energy barriers slowing down the spin dynamics before the SG transition ( T f <T <T* ) suggesting an intermediate Griffiths phase before the SG state. Our results reproduce qualitatively some findings of LiHo x Y 1 − x F 4 as the rounded maximum of χ 3 behavior triggered by RF and the deviation of the conventional relationship between the T f and T**. |
publishDate |
2019 |
dc.date.accessioned.fl_str_mv |
2019-08-29T02:35:26Z |
dc.date.issued.fl_str_mv |
2019 |
dc.type.driver.fl_str_mv |
Estrangeiro info:eu-repo/semantics/article |
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info:eu-repo/semantics/publishedVersion |
format |
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dc.identifier.uri.fl_str_mv |
http://hdl.handle.net/10183/198633 |
dc.identifier.issn.pt_BR.fl_str_mv |
1098-0121 |
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001097228 |
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1098-0121 001097228 |
url |
http://hdl.handle.net/10183/198633 |
dc.language.iso.fl_str_mv |
eng |
language |
eng |
dc.relation.ispartof.pt_BR.fl_str_mv |
Physical review. B, Condensed matter and materials physics. Woodbury. Vol. 99, no. 1 (Jan. 2019), 014203, 8 p. |
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info:eu-repo/semantics/openAccess |
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openAccess |
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application/pdf |
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