We have studied the role of long-range interactions on the thermodynamics of magnetic systems. We have simulated, through the Monte Carlo method, magnetization curves of a two-dimensional classical Ising model including a long-range dipole-dipole-like interaction, where the range of interaction is tuned by a parameter ␣. Based on the conjectures of Tsallis statistics, we show that, for ␣/dр1 (dϭ2), the appropriate form of the equation of state is given by M /Nϭm(T*,H*) with T*ϵT/N* and H*ϵH/N*. The normalization factor N*͓N*ϵ(N (1Ϫ␣/d) Ϫ1)/(1Ϫ␣/d)͔ emerges from the nonextensivity of thermodynamic variables of energy type. The crossover from nonextensive to extensive behavior at ␣/dϭ1 occurs smoothly and similarly to other quite different systems, thus suggesting it to be a general result. ͓S0163-1829͑97͒06009-8͔ PHYSICAL REVIEW B
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.