MAGNETIC-PROPERTIES OF BINARY DISORDERED ALLOY

A model binary alloy A(x) B-1-x, where A and B represent ferromagnetic and paramagnetic transition metal respectively is considered within t he framework of periodic Anderson model, and the effects of d-level di sorder and variation of electron concentration due to alloying on the magnetic properties are investigated. The phase boundary, thermal beha vior of magnetization and susceptibility of the alloy are obtained usi ng HF approximation for the Coulomb interaction and the virtual crysta l approximation for d-level disorder. The ferromagnetic state of alloy vanishes at a critical concentration x(c) which depends on d-band wid th, strength of s-d hybridization and the Coulomb interaction. The re- entrant magnetic phase is found within a small region of x for alloy w ith narrow d-band. For x less than or similar to x(c), the magnetic pr operties resemble that of spin-glass system. For x << x(c), the alloy behaves like a Pauli paramagnet. The re-entrant and spin-glass-like ph ases are associated with the increase in d-level population as tempera ture decreases. Local moment for x similar or equal to 1 decreases wit h temperature up to T-c whereas the reverse is the situation for alloy exhibiting spin-glass-like behavior.