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Abstract

The magnetization M(T,t) of high Tc superconducting BiCaSrCuO andBaErCuO was measured via the BTi SQUID susceptometer. To understand the glassy state and fluxoids trapped in superconductors, M(T,t), due to the trapped fluxoids, was measured as a function of T and time t, and it was found to decay with 1n(t). The rate, r = (dM/Mo)/(dt/t), was found to increase with T initially and found to have a maximum near 70K when a sample was cooled in 10G, and near 50K in 300G, respectively. In contrast, in BaLaCuO and SrLaCuO, r was reported to increase with T and H3 by which the existence of glassy state was suggested by Muller et al. The maximum decay rate appears where the magnetization changes rapidly. The observed decay rate can be understood in terms of fluxoid creeping idea of Anderson with a minor modification, i. e., introducing the effective volume V(T,H) occupied by the fluxoid bundles.