Hard-spin mean-field theory of a three-dimensional stacked-triangular-lattice system

Abstract

Closed form solutions to the hard-spin mean-field equations are constructed for the three-dimensional stacked triangular system. The phase diagram of this system is examined. The free energy of the system is calculated within the same approximation to identify the thermodynamically stable states in the phase diagram. A second-order phase transition line is found to exist for very small values of the external field. Our results display the details of the structure of the multicritical region within the hard-spin mean-field theory approximation. © 1995 The American Physical Society.