A spin-1/2 model for the Curie temperature of binary superlattices containing alloy disordered interfaces

A. Khater, M. Abou Ghantous, M. Fresneau

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    Abstract

    A theoretical model is presented on a simple cubic lattice to determine the Curie temperature phase diagrams for superlattices A2(Ap1 B1-p1)(Ap2 B1-p2)B2. These are considered to consist of periodic cells containing two layers of spin-1/2 A atoms, two layers of spin-1/2 B atoms and alloy disordered (Ap1 B1-p1)(Ap2 B1-p2) double layer interfaces in between, that are characterised by a random arrangement of the A and B atoms. The model is general and can be used for ferro- or anti-ferromagnetic A-B exchange coupling. The A-A and B-B exchange couplings are considered ferromagnetic. An effective field theory is employed to calculate the Curie temperature TC phase diagrams as a function of the two-dimensional (2D) alloy concentrations p1 and p2. The needed superlattice exchange constants are determined by calculating the TC phase diagram for an equivalent bulk alloy and comparing with known experimental data. The theoretical phase diagram results for the considered superlattices are presented for different values of the 2D concentrations and compared with those for a spin-1/2 Ising multilayer superlattice A2(Ap B1-p)B2 with concentrations 0≤p≤1. The concentration dependence of the phase diagram is an important feature of this work allowing a useful experimental analysis of similar systems.

    Original languageEnglish
    Pages (from-to)305-315
    Number of pages11
    JournalJournal of Magnetism and Magnetic Materials
    Volume247
    Issue number3
    DOIs
    Publication statusPublished - Jun 2002

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    Keywords

    • Effective field theory and Ising films
    • Multilayers
    • Phase diagrams
    • Superlattices

    ASJC Scopus subject areas

    • Electronic, Optical and Magnetic Materials
    • Condensed Matter Physics

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