Nonequivalent Ensembles for the Mean-Field φ⁶ Spin Model

Nonequivalent Ensembles for the Mean-Field φφ66 Spin Model

We derive the thermodynamic entropy of the mean field φφ6 spin model in the framework of the micro-canonical ensemble as a function of the energy and magnetization. Using the theory of large deviations and Rugh's micro-canonical formalism we obtain the entropy and its derivatives and study the thermodynamic properties of φφ6 spin model. The interesting point we found is that like φ4 model the e...

Negative magnetic susceptibility and nonequivalent ensembles for the mean-field φ spin model

We calculate the thermodynamic entropy of the mean-field φ spin model in the microcanonical ensemble as a function of the energy and magnetization of the model. The entropy and its derivative are obtained from the theory of large deviations, as well as from Rugh’s microcanonical formalism, which is implemented by computing averages of suitable observables in microcanonical molecular dynamics si...

Mean field theory for Heisenberg spin glasses

2014 The infinite-ranged spin glass model is studied in the general case of m-component spins. Results for the magnetization laws, the shape of the phase diagram, the nature of the transitions are presented. J. Physique LETTRES 42 (1981) L-103 L-106 1 PI MARS 1981, Classification Physics Abstracts 05.50 75.50K The infinite-ranged model [1], introduced by D. Sherrington and S. Kirkpatrick (SK), ...

Mean field models for spin glasses

Translation from physics: ‘Glass’: a material which is hard and inflexible (like a solid) but is not completely ordered or lattice-like in its microscropic structure (thus, unlike a crystal or simple metals). ‘Spin’: pertaining to the magnetic spins of ions in a material. ‘Spin glass’: a material, effectively solid, which contains some irregular distribution of magnetizable ions. Basic laborato...

Thermodynamic versus statistical nonequivalence of ensembles for the mean-field Blume-Emery-Griffiths model