Cluster-variation-method simulations of the magnetic phase diagrams with competing magnetic interactions

The alloying of isomorphic (Formula presented) ferromagnetic (Formula presented), (Formula presented), and antiferromagnetic (Formula presented) yields pseudobinary ((Formula presented)) compounds whose magnetic phase diagrams display paramagnetic, ferromagnetic, antiferromagnetic, spin glass, and reentrant spin glass regions, depending on concentration and temperature. We show that it is possible to reproduce many features of these phase diagrams, namely, the Curie and Néel temperatures, using a simple Ising Hamiltonian, treated in the pair approximation of a square cluster-variation method, with only three dominant magnetic interactions between 3(Formula presented) elements, the magnetic role of Pt being neglected. The homoatomic interactions ((Formula presented)) are given by the magnetic transitions of the binary compounds, whereas the heteroatomic (Formula presented) interaction is either parametrized or fitted and left free to vary with concentration. © 1997 The American Physical Society.

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