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Journal articles
Phase space gaps and ergodicity breaking in systems with long range interactions
Abstract : We study a generalized isotropic XY-model which includes both two-spin and four-spin mean-field interactions. This model can be solved in the microcanonical ensemble. It is shown that in certain parameter regions the model exhibits gaps in the magnetization at fixed energy, resulting in ergodicity breaking. This phenomenon has previously been reported in anisotropic and discrete spin models. The entropy of the model is calculated and the microcanonical phase diagram is derived, showing the existence of first order phase transitions from the ferromagnetic to a paramagnetic disordered phase. It is found that ergodicity breaking takes place both in the ferromagnetic and the paramagnetic phases. As a consequence, the system can exhibit a stable ferromagnetic phase within the paramagnetic region, and conversely a disordered phase within the magnetically ordered region.
Keywords :
Ergodicity breaking
Long-range interaction
Cited literature [8 references]
https://hal-ens-lyon.archives-ouvertes.fr/ensl-00184817
Contributor : Thierry Dauxois <>
Submitted on : Friday, November 2, 2007 - 9:16:47 AM
Last modification on : Monday, October 12, 2020 - 10:27:30 AM
Long-term archiving on: : Monday, April 12, 2010 - 1:12:23 AM
Contributor : Thierry Dauxois <>
Submitted on : Friday, November 2, 2007 - 9:16:47 AM
Last modification on : Monday, October 12, 2020 - 10:27:30 AM
Long-term archiving on: : Monday, April 12, 2010 - 1:12:23 AM
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