CRITICAL PROPERTIES OF PURE AND DILUTED HEISENBERG SPIN SYSTEMS

Abstract

In this thesis we have made an attempt to understand the critical properties of pure and diluted Heisenberg spin systems using a position space renormaliz,ation group (HG) treatment. The interest in this problem arises from experi-mental as well as theoretical considerations. For quite some time there is theoretical interest in understanding, how critical properties of magnetic models like Ising model and Heisenberg model change when one dilutes the system randomly More recently, much attention has been given to the complex critical phenomena that occurs as the dilution approaches the percolation limit. Much of the initial theoretical work has been done on Ising model for the obvious reason of its simpli- city. In this thesis, we extend these studies to systems with vector spins...