Peak effect, oxygen deficiency, and scaling behavior of magnetization for YBa 2Cu 3O 7−δ crystals prepared by top-seeded solution growth

Abstract

We present the magnetic properties of YBa 2Cu 3O 7−δ crystals prepared by top-seeded solution growth (TSSG) [1]. The crystals showed the peculiar peak effect (fish-tail) for fields parallel to the c-axis, for which the hysteresis width in the magnetic isotherm M( H) showed a single maximum at | H p| > 0. This M( H) was observed up to 85 K, just below the maximum T c = 86 K, and was found to be insensitive to various oxygen annealings. On the other hand, oxygen reduction, which resulted in a decrease in T c by up to 4 K, showed a scaling behavior of the normalized ( M · H) for both temperatures and oxygen contents, indicating a single pinning mechanism. This implies that the oxygen vacancies or twin planes are unlikely to account for this peak effect. We also discuss the effects of defects such as twisted boundaries, localized stacking faults, and impurities on the peak effect. Together with the fish-tail associated with oxygen vacancies, we suggest that the peak effect is not related to specific ions, but to material processing.