Surface magnetic properties of the Ising model with a diluted free surface

Abstract

A semi-infinite ferromagnetic simple cubic Ising lattice which has nonmagnetic impurities substituted for the magnetic species only at the surface is investigated with the use of a new type of effective-field theory with correlation. The surface magnetism is examined as a function of modified exchange ${J}_{s}=J(1+\ensuremath{\Delta})$ and concentration $P$ of magnetic atoms at the surface. The critical value ${\ensuremath{\Delta}}_{c}$, transition temperatures ${T}_{c}^{s}$, and phase diagram for surface ordering are obtained as functions of $P$ and $\ensuremath{\Delta}$. The reduced magnetization curves of surface and bulk are also studied. We obtain some characteristic behaviors of magnetism at the diluted surface.