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

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 Jₛ=J(1+Δ) and concentration P of magnetic atoms at the surface. The critical value Δc, transition temperatures Tcˢ, and phase diagram for surface ordering are obtained as functions of P and Δ. The reduced magnetization curves of surface and bulk are also studied. We obtain some characteristic behaviors of magnetism at the diluted surface.