Theory of systems with random Ising bond interactions in the paramagnetic phase

Publisher Website
Google Scholar
Abstract
A theory of the thermodynamic properties (spin correlation functions, susceptibility and specific heat) in the paramagnetic phase of Ising systems with various forms of random bond arrangement is developed. It represents an extension of the random phase approximation (RPA). The difference equation for the spin correlation functions which has random coefficients is solved using the coherent potential approximation (CPA), and the various parameters calculated self-consistently. Results for the quenched dilute bond case are in good agreement with other theories. For a truncated Gaussian distribution of bond strengths it is found that the transition temperature and other properties are fairly universal functions of the mean square of the distribution. The transition to a ferromagnetic phase disappears when the concentration of negative exchange bonds becomes large enough, apparently because of spin glass formation. Results for various binary distributions are also given.

This publication has 37 references indexed in Scilit: