Ferromagnetism and spatial long-range order in binary alloys

Abstract

Ferromagnetism and chemical long-range order in binary alloys are studied within the mean-field approximation. The ordering process is driven by pairwise interatomic forces and the magnetic interactions are of the Ising type. Only nearest-neighbour forces are included. It is found that there is a strong influence of one phenomenon on the other, with either the critical order-disorder transformation temperature or the Curie temperature appreciably altered from the corresponding isolated values. The interplay of the two phenomena yields in some cases unusual sequences of phases as a function of temperature. The case of Co_xFe_1-x alloy is examined along these lines and it is found that the phase diagram can be well reproduced for 0.3<x<0.7, including the observed asymmetry around x=0.5.