Lower Critical Fields in Bi-2212 and Bi-2223 Superconductors

Abstract
Low-field microwave magnetoabsorptions were observed for Bi-2212 and Bi-2223 specimens, and the lower critical fields were investigated. The principal values of H c1 were determined over a temperature range from 4 to 60 K. Their temperature variations may be related to the low dimensional character of superconductivity.