Magnetic phase transition in amorphous and crystalline ferromagnets

Abstract

For amorphous FeNi- and FeW-base alloys and for disordered crystalline Fe 70Ni 30 the asymptotic critical exponents and the temperature dependence of the effective exponent λ( T) are investigated. No significant deviations from the 3d-Heisenberg exponents were found in all cases. For λ( T) the characteristic non-monotonic temperature dependence is observed as predicted by the correlated molecular field theory. Anomalies in the Arrott plots which occur in all disordered alloys as well as in high-purity crystalline Ni at very low fields are discussed.