Phase transitions in the three-state Ising spin-glass model with finite connectivity

• Autor(a) principal: Erichsen Junior, Rubem
• Data de Publicação: 2011
• Outros Autores: Theumann, Walter Karl
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Institucional da UFRGS
• Texto Completo: http://hdl.handle.net/10183/101840
• topic: Física estatística; Análise estatística; Interacoes de campo cristalino; Entropia; Modelo de ising; Diagramas de fase; Vidros de spin

The statistical mechanics of a two-state Ising spin-glass model with finite random connectivity, in which each site is connected to a finite number of other sites, is extended in this work within the replica technique to study the phase transitions in the three-state Ghatak-Sherrington (or random Blume-Capel) model of a spin glass with a crystal-field term. The replica symmetry ansatz for the order function is expressed in terms of a two-dimensional effective-field distribution, which is determined numerically by means of a population dynamics procedure. Phase diagrams are obtained exhibiting phase boundaries that have a reentrance with both a continuous and a genuine first-order transition with a discontinuity in the entropy. This may be seen as “inverse freezing,” which has been studied extensively lately, as a process either with or without exchange of latent heat.