On the magnetically dilute Heisenberg and Ising ferromagnetics

The problem of a randomly dilute Heisenberg or Ising ferromagnetic is discussed on the basis of expansions of susceptibility in inverse powers of temperature. The first six significant coefficients in such expansions have been found, for any lattice and any spin value. The series are used to estimate the dependence of Curie temperature, ϑ c, on concentration of magnetic elements, p, for simple cubic, body-centred cubic and face-centred cubic lattices and spins ½ and 1. Near p = 1, it is found that for the Ising models ϑ c(p)=p ϑ c(1) whereas for the Heisenberg models ϑ c(p) < p ϑ c(1).