高Tc氧化物YBa2Cu3Oy超导体中的磁通蠕动

利用观察磁化随时间变化的方法研究了高T_c氧化物YBa₂Cu₃O_y超导体临界态的磁通蠕动。实验结果表明,零场冷却的样品,加一个所选定场值的磁场,产生的磁化随对数时间线性衰减,同时伴随有磁通跳跃的发生。磁化衰减速率dM/dlnt随外场H的变化在H=3H_P附近有一峰值,并认为与弱连结超导电性的存在有关。在77K以上温度,dM/dlnt随温度的升高而单调减小。讨论了钉扎磁通的热激活能U_{0关键词：}

FLUX CREEP IN HIGH Tc YBa2Cu3Oy BULK SUPERCONDUCTOR

Flux creep in high T_c oxide YBa₂Cu₃O_y superconductor in critical state has been studied by observing variation of magnetization with time. Experimental results show that for the zero field cooling sample, the magnetization decays with time following the law M∝lnt over the observation time period, and this process accompanies by the occurrence of flux jumps. The rate of the magnetization decay dM/dlnt, as a function of the field, exhibits a maximum near H=3H_P. It is believed to be related to weak link superconductivity. dM/dlnt decreases monoto-neously with the rising temperature in the temperature range above 77K. Finally, a discussion is made about the activation energy of the flux lines U₀.