不均匀超导体中的历史效应  

HISTORICAL EFFECT IN INHOMOGENEOUS SUPERCONDUCTOR

作　　者：刘洋[1] 罗虹[1] 冷祥[1] 王智河[1] 邱里[1] 丁世英[1] 林良真[2] 

机构地区：[1]南京大学固体微结构实验室,物理系,南京210093 [2]中国科学院,电工研究所,北京100081

出　　处：《低温物理学报》2002年第4期241-247,共7页Low Temperature Physical Letters

基　　金：国家科技部 (NKBRSF G1999 0 6 46 );国家自然科学基金 (No .199940 16 )资助项目~~

摘　　要：我们提出一个模型 ,解释了磁通钉扎不均匀超导体的历史效应 .钉扎不同由不同的临界电流密度jc 来表征 .基于这种模型以及磁通扩散方程 ,数值计算表明不均匀超导体的V I输运特性曲线具有明显的历史效应 ,即升降电流时电压具有不可逆性 ,且这种不可逆性对电流扫描速度非常敏感而对磁场很不敏感 .我们的银包套Bi2 -xPbxSr2 Ca2 Cu3Oy 电输运实验和文献的同样都显示出这种不可逆性 。We proposed a model accounting for a kind of history effect in an inhomogeneous superconductor with flux creep. The model consists of weaker and stronger region of flux pinning whose strength depicted by different critical current densities. Based on the model and highly non-linear vortex diffusion equation, we numerically observed a kind of history effect in the characteristic V-I curve at different sweeping rate of applied current dI/dt and magnetic fields B-a. Electric transport measurement was conducted of characteristic V-I curve of Ag-sheathed Bi-{2-x}Pb-xSr-2Ca-2Cu-3O-y tapes immersed in liquid nitrogen in applied fields. Hysteresis loop of V-I curve at certain dI/dt and Ba was observed, confirming the model. Hence there exists a new mechanism responsible for the history effect of j-c in vortex matter.

关 键 词：不均匀超导体 历史效应 临界电流 钉扎系统 磁通 磁场 低温物性 

分 类 号：O511.4[理学—低温物理]