Vortices dynamics and critical currents of superconductor having holes and slits with de Gennes boundary condition

Abstract

Critical current of the superconductor is one of the important quantities determining the quality of the superconductor. Many efforts have been done to enhance this quantity including the use of holes in different form of lattices fabricated on the superconductor. In the enhancement of critical current using such holes, it is usually understood that the enhancement process is due to the commensurate effect between flux quantization with the structure of the lattice hole. However, there is another explanation that the enhancement is caused rather by the vortex-hole interaction compared to such an effect. To review this, we investigate the phenomena at superconductor having holes and slit to see the roles of those structure in increasing the pinning force responsible for the critical current enhancement. The investigation was done numerically through the calculation of vortices dynamics using time dependent Ginzburg-Landau equation on the superconductor exposed under electric current and magnetic field. To account the effect of the boundary, the holes and the slits are accompanied by de Gennes boundary condition. The result supports the explanation that the enhancement of the critical current caused by the addition of an array of hole or slit is due to the interaction of vortex and hole or slit. The result also indicates that the use of a negative de Gennes extrapolation length at the superconductor boundary enhancing the critical current higher than the use of superconductor-vacuum.