Star Ark

Abstract

The concentration dependence of the ferromagnetic ordering temperature, Tc(p) in a dilute bond Ising model,, is studied for several long-range interactions near the limit p to 0, Tc to 0. The critical region of the random Ising model transition, occurring at all finite Tc, is shown to shrink to zero as p approaches zero. For dipolar interactions, spin glass ordering may occur at sufficiently small p.