Role of grain boundary networks in vortex motion in superconducting films

作     者：刘宇 薛峰 苟晓凡 Yu Liu;Feng Xue;Xiao-Fan Gou

作者机构：College of Mechanics and MaterialsHohai UniversityNanjing 211100China 

出 版 物：《Chinese Physics B》 (中国物理B（英文版）)

年 卷 期：2023年第32卷第12期

页      面：528-533页

核心收录：

学科分类：07[理学] 070205[理学-凝聚态物理] 0702[理学-物理学] 

基　　金：Project supported by the National Natural Science Foundation of China (Grant Nos. 12232005 and 12072101) 

主　　题：grain boundary network Voronoi tessellation synergistic effect intensity factor of synergistic effect vortex motion combined channels 

摘      要：We study the vortex dynamics of the polycrystalline superconductors in the presence of both random point defects and the generated grain boundary(GB) networks with Voronoi diagram. The synergistic effect of adjacent GBs on restricting the vortex motion in intragranular region is proposed and the corresponding intensity factor of the synergistic effect which characterizes the strength of the synergistic restriction of adjacent grain boundaries is also determined in the present *** interconnected GBs offer easy-flow channels for vortices in addition to pinning effects on the vortices. The combined channels and the vortex flow patterns in the superconducting film are analyzed in detail from molecular dynamics simulations. Furthermore, it is discovered that the critical current increases with the decrease of magnetic field intensity,temperature, and the average grain size. The large number of vortices results in the enhanced repulsive interaction forcing the vortices to move out from the GBs. The thermal depinning from GBs leads to the lower Lorentz force range. The increase of the grain size causes the number of GBs to decrease. In summary, these effects leads the critical current to become a decreasing function of magnetic field, temperature, and grain size.