Visualizing the mechanism that determines the critical current density in polycrystalline superconductors using time-dependent Ginzburg-Landau theory

Abstract

In polycrystalline superconducting materials optimized for high critical current density $({J}_{C})$ in high magnetic fields, the mechanism that determines ${J}_{C}$ has long remained uncertain because of the complicated manner in which the fluxon-fluxon and fluxon-microstructure forces combine. In this work, the time-dependent Ginzburg-Landau equations are used to produce visualizations of fluxons at ${J}_{C}$ that show the disorder in the pinned part of the flux-line lattice and the motion of those fluxons along grain boundaries that cause dissipation. Calculated values of ${J}_{C}$ are consistent with experimental data.