A mean field method for disordered magnetic alloys with application to FCC iron-nickel.

Abstract

We present a mean field model for the magnetism of random alloys. The reader is introduced to the philosophy of the mean field approach with an example of a simple ferromagnet. The special problem presented by random arrangement of alloy components on a lattice is discussed before we describe the technique we have developed. Our approach simplifies the treatment of these complicated systems by classifying sites according to the characteristics of their local environments. We apply this technique to both a fictional 1-D chain and to a real 3-D alloy series (fcc Fe-Ni). Fair success in modelling the complex magnetic behaviour characteristic of mixed exchange alloys (such as flattened magnetization curves, departure of the saturation moment from the Slater-Pauling curve, a complex phase diagram, and para-process susceptibility) is achieved.