Barrier or easy-flow channel: The role of grain boundary acting on vortex motion in type-Ⅱ superconductors  

作　　者：Yu Liu Xiao-Fan Gou Feng Xue 刘宇;苟晓凡;薛峰(College of Mechanics and Materials,Hohai University,Nanjing 211100,China)

机构地区：[1]College of Mechanics and Materials,Hohai University,Nanjing 211100,China

出　　处：《Chinese Physics B》2021年第9期499-505,共7页中国物理B（英文版）

基　　金：Project supported financially by the National Natural Science Foundation of China(Grant No.12072101);the Fundamental Research Funds for the Central Universities,China(Grant No.2018B48714).

摘　　要：Grain boundaries(GBs),as extremely anisotropic pinning defects,have a strong impact on vortex motion in type-Ⅱsuperconductors,and further on the macro level dominates the superconductivity for example the critical current density.Many previous studies indicated that mostly GB plays the role of a strong barrier for vortex motion,while an easy-flow channel just under some certain conditions.In order to thoroughly make clear of the questions of what is exactly the role of GB on vortex motion and how it works,in this article we developed a large scale molecular dynamic model and revealed the action of GB on vortex motion in type-Ⅱsuperconductors.The most significant finding is that the role of GB on vortex motion can be changeable from a barrier to an easy-flow channel,and which is intrinsically determined by the competition effect correlated with its action on vortex between in the GB and no-GB regions.Such the competition effect essentially depends on the attributes of both the GB(described by the GB strength and angleθ)and no-GB pining regions(by the relative disorder strengthα_(p)/α_(v)).Specifically,for a YBa_(2)Cu_(3)O_(7-x)(YBCO)sample,to obtain a clear knowledge of vortex motion in GB region,we visualized the three typical trajectories of vortices during the three vortex movement stages.Further,in order to understand how GB results in the macro current-carrying property,corresponding to the current-voltage relation of the YBCO conductor,we obtained the average velocity v_(y) of vortices varying with their driving force,which is nearly identical with the previous observations.

关 键 词：type-II superconductors grain boundary(GB) vortex motion competition effect GB strength the relative disorder strengthαp/αv 

分 类 号：O511.3[一般工业技术—材料科学与工程]