Long-range interactions and nonextensivity in ferromagnetic spin models

SERGIO CANNAS; FRANCISCO TAMARIT

PHYSICAL REVIEW B

AMER PHYSICAL SOC

Lugar: New York; Año: 1996 vol. 54

1098-0121

The Ising model with ferromagnetic interactions that decay as is analyzed in the nonextensive regime, where the thermodynamic limit is not defined. In order to study the asymptotic properties of the model we propose a generalization of the Curie-Weiss model, for which the thermodinamic limit is well defined under certain conditions. We conjecture that mean-field theory is exact in the last model and this conjecture is supported by Monte Carlo heat-bath simulations in the d=1 case. Moreover, we confirm a recently conjectured scaling by Tsallis that allows for a unification of extensive and nonextensive regimes.