MEAN-FIELD ANALYSIS OF HIGH-FIELD MAGNETIZATION CURVES OF GLASSES - STRUCTURE OF MAGNETIC AGGREGATES

Magnetic properties of ions in glasses are usually deduced from the lo w held susceptibility data and are expressed as an effective localised moment S-eff and a paramagnetic Curie-Weiss temperature theta(p), the latter being indicative of the strength of the average interaction be tween the ions. We show that the temperature dependent high field magn etization curves (M versus eta) provide more information not only on t he average interaction but also on the structure of the aggregates. We apply simple mean field theory to the Brillioun function and show how the data can be treated to test the existence of a single interaction constant, separate the contribution of the noninteracting ions and al so see, in the case of two ions, whether one ion penetrates into the a ggregate structure of the other.