A method for phase diagrams of spin-1 Ising ferromagnetic systems

摘要

A method in Ising models is introduced by using the effective field theory (EFT) with correlations. In the present method, for the spin-1 Ising ferromagnetic systems with three coordination numbers q (q = 3,4 and 6), we have derived a set of linear equations by taking as a basis the thermal averages of a central spin and a perimeter spin at the site i, which is defined within spin identities and differential operator technique. By solving numerically the set of linear equations derived individually for the Ising systems, we have evaluated the phase diagrams of both the spin-1 Ising ferromagnetic systems with a single-ion anisotropy and the spin-1 transverse Ising ferromagnetic systems with a transverse field. The present results of critical transverse field for the spin-1 transverse Ising systems improve those obtained by the pair approximation. (C) 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. [References: 29]