Magnetic phase diagrams of Nb xFe 100− x and Ta xFe 100− x amorphous alloy systems

Abstract

The magnetic phase diagrams of Nb x Fe 100− x and Ta x Fe 100− x amorphous alloy systems have been investigated. The phase transition from the paramagnetic state to the spin-glass state was observed above about x=34% for Nb x Fe 100− x and x=36% for Ta x Fe 100− x amorphous alloys. The re-entrant spin-glass behavior was confirmed below these concentrations. The saturation magnetic moment M s of both amorphous alloy systems decreases with increasing x. The value of M s at the concentration where the spin-glass state takes place is small of about 0.4 μ B per Fe atom due to the short average Fe–Fe interatomic distance, compared with that of other Fe-based amorphous alloy systems such as La–Fe, Ce–Fe and Lu–Fe. The magnetic phase diagrams of the Nb–Fe and Ta–Fe amorphous alloy systems are similar to those of other Fe-based amorphous alloy systems, although the Curie temperature and the magnetic moment of the former two systems are much lower than those of the latter alloys systems.