Order-disorder phase transition of the CoxFe1-x system

• Published in: Journal of magnetism and magnetic materials 2003-07, Vol.263 (1-2), p.182-191
• Main Authors: LOPEZ-CHAVEZ, Ernesto, DE LANDA CASTILLO-ALVARADO, Fray
• Format: Article
• Language: English
• Subjects: Band and itinerant models; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Equations of state, phase equilibria, and phase transitions; Exact sciences and technology; General studies of phase transitions; General theory and models of magnetic ordering; Magnetic properties and materials; Order-disorder and statistical mechanics of model systems; Order-disorder transformations; statistical mechanics of model systems; Physics
• ISSN: 0304-8853
• DOI: 10.1016/S0304-8853(02)01563-9

The order-disorder phase transitions in binary alloys with magnetic interactions are studied. We introduced an electronic theory for magnetic binary alloys, which is an extension of the cluster-Bethe lattice method. In this approximation we incorporate electronic correlations, itinerant and localize nature of electrons 3d, and both long-range and short-range chemical correlations. The magnetism is described by means of a Hubbard Hamiltonian that in conjunction with Green's functions techniques is used to calculate local densities of electronic states. For it we take an atom in the real lattice and it is joined to a Bethe's lattice with the same coordination number. The diagram for order-disorder phase transition is obtained. It is achieved by coupling the electronic theory introduced here, to combinatorial theory developed by Kikuchi. The first is used for calculating the alloy internal energy so long as the second is used for obtain the configurational entropy. An application to order-disorder transition of CoxFe1-x is studied and good agreement with experiment is obtained.