Critical properties of site-diluted Heisenberg and Ising magnets

Abstract

A simple modification of the real-space renormalisation group method is used to discuss critical behaviour of site diluted spin-1/2 Ising and Heisenberg ferromagnets in two and three dimensions. The critical parameters and critical exponents are evaluated, and are shown to be in good agreement with the exact results and series calculations for site-diluted Ising ferromagnets on the square and triangular lattices. Good values of the critical parameters have also been obtained for the site-diluted Heisenberg and Ising models in two and three dimensions using the Migdal-Kadanoff approximation (1976).