PARAMAGNETIC MEISSNER EFFECT OF HIGH T-C SUPERCONDUCTORS II - A PHENOMENOLOGICAL LOCAL MOMENT MODEL

A range of powdered Bi:2 212 samples exhibiting the paramagnetic Meiss ner effect (PME) are systematically examined. Interpretation of the re sults is made in terms of a phenomenological model in which there is a concentration within the material of small local moments that can be polarized during a field cooling. Information about the magnitudes of these local m0oments and their distribution are deduced. Relations bet ween the local moments and the particle sizes, the weak link, oxygen c ontent and the interactions between the local moments are also discuss ed. Comparison of the results from small particles and bulk samples sh ows that conclusions obtained from small particle experiments are reli able and universal.