Simulation And Experiment Study Of High-T_c Superconductor With Grain Boundary

In high-temperature superconductor YBa2Cu3O7-δ film, twin boundaries (TB) are very siginificant existing, which caused the interests of scientists worldwide. With the presence of TB in YBCO sample, the resaerach on behavior of a flux quantum have been studied by scienticest both theoretically and experimentally. However, there are quantities of twin boundaries (TBs) on YBa2Cu3O7-δ single crystals making the study quite complicated. Instead, we consider the influence of an individual artificial YBCO bicrystal grain boundary in our research. Firstly, we started the vorties dynamic simulation on YBCO film with grain boundary, where we consider the superconcting material as an infinite dimensional surface. With periodic boundary conditions and Runge-Kutta method, we proceed molecular dynamics simulation. It’s found that the angle between grain boundaty and x-axis has significant impact on the distribution of vortices as well as their horizontal and vertical velocities. From the Ⅰ-Ⅴ curves in simulation, we also see the critical current value has related to the quantity of vortices and pinning sites. With more number of vortices or less number of pinning sites, the vortices start moving from pinning state to flow state earlier. At last, we went on verfication experimentally on YBCO sample with 30°,60°inclined along x-axis as well as no GB. The consistent concludsions have been found to prove the reasonability of the simulation process.