S-wave pairing: A study of low-field dc magnetization in micrometer-sized HTSC powders

An extensive study of the low-field (μ0H ≤ 8 mT) dc initial susceptibility χin has been performed using micrometer-sized HTSC powders of varying sizes and methods of preparation. It is found, as before, that χin(T) is essentially constant for T approx-lt 0.4Tc. This supports s-wave pairing and implies no zeros of the gap on the fermi surface. Additionally, χin(T) finds reasonable description in a London model for superconducting spheres and a two-fluid model λ(T)