The competition of bulk and surface fields in a transverse Ising model thin film

Abstract

Monte Carlo simulations have been performed to investigate the equilibrium phase behaviour of a transverse Ising model in a thin-film geometry under the action of competing surface fields. This model is a classical isotropic vector spin model with a ferromagnetic Ising Hamiltonian and a transverse field applied perpendicular to the Ising z-axis. For finite values of the transverse field strength, , the model displays an interface localization transition with a spontaneous magnetization of the film below a critical temperature Tc. However, in the limit , no spontaneous magnetization of the film is observed. In the two-phase regime, below Tc, a degeneracy exists in the magnetization profiles across the film between states of positive and negative total magnetization. The interface localization transition temperature lies below the bulk critical temperature of the film for competing surface fields.