Effects of critical temperature inhomogeneities on the voltage-current characteristics of a planar superconductor near the Berezinskii-Kosterlitz-Thouless transition

摘要

We analyze numerically how the voltage-current (V-I) characteristics near theso-called Berezinskii-Kosterlitz-Thouless (BKT) transition of 2Dsuperconductors are affected by a random spatial Gaussian distribution ofcritical temperature inhomogeneities with long characteristic lengths (muchlarger than the in-plane superconducting coherence length amplitude). Oursimulations allow to quantify the broadening around the average BKT transitiontemperature of both the exponent alpha in V I^alpha and of the resistance V/I.These calculations reveal that strong spatial redistributions of the localcurrent will occur around the transition as either I or the temperature T arevaried. Our results also support that the condition alpha=3 provides a goodestimate for the location of the average BKT transition temperature, and thatextrapolating to alpha->1 the alpha(T) behaviour well below the transitionprovides a good estimate for the average mean-field critical temperature.