Surface phase diagrams of a random transverse Ising model

Abstract:

The effect of surface on the critical behaviour of a ferromagnetic Ising spin model in a random transverse surface and bulk fields is studied by the use of an effective field method within the framework of a single-site cluster theory. The state equations are derived using a probability distribution method based on the use of Van der Waerden identities. The complete phase diagrams are investigated when the transverse fields are bimodally and trimodally distributed. In particular, the influence of the transverse fields, exchange interaction strength ratio and the distribution parameter on the phase diagrams behaviour is examined in detail.