Magnetic properties of AuCo solid solutions and frequency dependent susceptibility maximum

Abstract

AuCo solid solutions of Co concentration ranging from 4 to 23 at.% are produced by simultaneous evaporation of both components on a substrate held at 14K. The susceptibility of the films (thickness 2 mu m) is determined in situ by applying AC magnetic fields of 0.6 to 11.5 mT and frequencies of 12 to 5500 Hz, DC fields can be superposed. The magnetic moment rises with Co concentration. Tf depends on frequency nu corresponding to in nu / nu 0=-TA/Tf. The representative 'activation' energy TA scales with Tf. The scaling factor Ta/Tf is independent of concentration and annealing temperature. TA, Tf and the magnetic moment increase with annealing.