Anomalous Temperature Dependence of Hc1 in High-Tc Superconductor YBa2Cu3O7-δ

Abstract
Temperature dependence of magnetization curves was measured on a polycrystalline sample of high-T c superconductor YBa2Cu3O7-δ. The lower critical field obtained from the magnetization curves has an anomalous temperature dependence, which may infer that a dimensional crossover occurs as observed in an artificial layered superconductor Nb/Cu.