Effect of Defect Potential Well Shape on the Critical Current and n-Value of a High-Temperature Superconductor

We report Monte Carlo simulation results on the influence of the defect potential well shape on the Abrikosov vortex pinning and the transport properties of a high-temperature superconductor. It is shown that variations in the effective defect width significantly affects both the critical current and the n-value of the current‒voltage characteristic. As the defect width increases from fractions to tens of coherence lengths, the critical current increases in a stepwise manner until saturation, while the n-value changes nonmonotonically due to enhanced vortex mobility on widened defects. Analysis of vortex configurations reveals an optimal range of well widths (from one to ten coherence lengths) that ensures the maximum transport characteristics of the material.