Paramagnetic Meissner effect of highTc superconductors IIA phenomenological local moment model

A range of powdered Bi:2 212 samples exhibiting the paramagnetic Meissner effect (PME) are systematically examined. Interpretation of the results 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 between the local moments and the particle sizes, the weak link, oxygen content and the interactions between the local moments are also discussed. Comparison of the results from small particles and bulk samples shows that conclusions obtained from small particle experiments are reliable and universal.