Effect of anisotropy on Curie temperature in Heisenberg ferromagnet

The variation of Curie temperature with small uniaxial anisotropy has been studied by using the Green's function technique. The scheme proposed by J.F. Devlin (1971) for overcoming the difficulty of Tsub(c)(D) → infinity as D → infinity, has been used, but unlike in Devlin's scheme all possible intersite correlations have been taken into account. The curve of Tsub(c) versus D/J obtained in the present study is found to be closer to experimental observations than that of M. Tanaka and Y. Kundo (1972). (author)