Magnetic Phase Transitions

Abstract

Phase transitions are an important class of physical phenomena with enormous practical applications which also raise fundamental theoretical problems. In magnetic systems both of these aspects are evident. It was the existence of magnetic order in materials like iron which first attracted attention to the subject of magnetism. With our enhanced understanding of the fundamental theory of magnetism these materials now form what is probably the most important testing ground of the theory of phase transitions since it is often possible to obtain a simple but realistic model Hamiltonian to describe the system. For example the most studied theoretical model which displays a phase transition is the Ising model and this forms a good description of some,magnetic systems.