Magnetic lattice gas

Abstract
We consider a lattice gas for which particles possessing magnetic moments can interact via magnetic long-range Kac potential and short-range intermolecular potential. From the exact equation of state of the lattice gas and the magnetization we construct and discuss phase diagrams in one and two dimensions. The appearance of any of the possible phases—nonmagnetic gas, nonmagnetic liquid, or magnetic liquid—is shown to depend crucially on the value of the parameter R, the ratio of the short-range (nonmagnetic) to long-range (magnetic) interaction strengths.