The transverse spin-1 Ising model with random interactions

Abstract The phase diagrams of the transverse spin-1 Ising model with random interactions are investigated using a new technique in the effective field theory that employs a probability distribution within the framework of the single-site cluster theory based on the use of exact Ising spin identities. A model is adopted in which the nearest-neighbor exchange couplings are independent random variables distributed according to the law P ( J ij )= pδ ( J ij − J )+(1− p ) δ ( J ij − αJ ). General formulae, applicable to lattices with coordination number N , are given. Numerical results are presented for a simple cubic lattice. The possible reentrant phenomenon displayed by the system due to the competitive effects between exchange interactions occurs for the appropriate range of the parameter α .