EFFECT OF DISORDER ON THE CRITICAL-BEHAVIOR OF A FERROMAGNETIC BINARYISING ALLOY

The effect of site and exchange disorders on the critical behaviour of a disordered ferromagnetic Ising binary alloy is studied by evaluatin g the magnetization and the susceptibility with the help of a cluster- variational method. The critical exponents gamma and gamma describing , respectively, the linear and nonlinear scaling of the susceptibility exhibit a non-monotonic temperature dependence for T > T(c). Gamma i ncreases with increasing disorder. The critical exponent beta increase s with disorder, whereas delta remains unaffected. A rapid shrinking o f the asymptotic critical region and variation of the limiting (T >> T (c)) values of gamma = THETA(p)/T(c) with the increase in disorder are observed.