Magnetic Field Dependence of Jc In NdBa_2Cu_3O_(7-#delta#) Single Crystals Grown Under Various O_2 Partial Pressures

摘要

NdBa_2Cu_3O_(7-#delta#) (Nd123) single crystals were grown by the horizontal-Bridgman like method under various O_2 partial pressures (0.1precentapprox 0.01precent) in Ar atmosphere. High quality Nd123 single crystals with T_c higher than 94.9K were obtained using YSZ boats. The enhancement of the magnetization with increasing field, i.e., fishtail or peak effect was observed in the hysteresis (M-H) loops in the field parallel to the c-axis of the single crystals grown under 0.1precent and 0.06precent O_2 pressure at around 77K. But it was not observed for the crystals grown under 0.05precent and 0.04precent O_2 atmosphere. This indicates the existence of an optimum O_2 pressure under which the amount of Nd/Ba substitution becomes the minimum in Nd123 single crystals.