A Modfied Form of Heisenberg's Theory of Ferromagnetism

R H Tredgold

Abstract

The Heisenberg theory of ferromagnetism is extended to include exchange interactions between atoms other than nearest neighbours. The calculation is carried through as far as the third approximation and a general expression for the susceptibility above the Curie point is obtained. A particular law of variation of exchange interaction with distance is investigated and it is shown that the results obtained reproduce the general features of the susceptibility versus temperature curves of real ferromagnetic materials.

https://sci-hub.tw/https://iopscience.iop.org/article/10.1088/0370-1298/67/2/306/pdf