The critical current density in type-II superconducting bulk materials

TL;DR

This paper investigates the temperature and magnetic field dependence of the critical current density in type-II superconductors using quantum vortex dynamics, revealing specific decay behaviors consistent with experiments.

Contribution

It introduces a quantum theory-based model for vortex dynamics that explains the temperature and magnetic field dependence of Jc in bulk superconductors.

Findings

Jc decreases weakly with temperature below T_dp

Jc follows a power-law decay between T_dp and T_f

Jc decays exponentially above T_f

Abstract

The critical current density Jc in type-II conventional and high-Tc superconducting bulk materials is investigated based on the quantum theory for the vortex dynamics. It is shown that for a constant magnetic field, the critical current density Jc decreases weakly with increasing temperature when T<T_dp(depinning temperature); when T_dp< T <T_f (boundary fluctuation temperature,Jc is power-law-decaying,and when T>T_f,Jc decays exponentially; while for a constant temperature, Jc first decreases, then increases after reaching a maximum, and finally decreases again as the magnetic field increases. These results are in agreement with the experiments.