AC SUSCEPTIBILITY AND TEMPERATURE MODULATION STUDIES OF GADOLINIUM

Studies of the low field (Hrms<or approximately=14 A m -1) initial AC susceptibility chi i of unannealed and annealed gadolinium around the Curie temperature (Tc approximately 290K) are reported. The frequency dependence of chi i is found to be characteristic of an impurity diffusion magnetic after effect of mean relaxation time tau approximately 0.3 s. A comparison of thermal modulation experiments for annealed and unannealed samples shows that annealing greatly reduces both the observed temperature hysteresis of chi i and the thermal relaxation of domain properties in the temperature region of domain nucleation.