Critical currents for vortex defect motion in superconducting arrays

TL;DR

This paper investigates vortex motion in 2D Josephson junction arrays, measuring critical currents and pinning barriers, and finds good agreement with experiments especially in the frustrated case, challenging existing theories.

Contribution

It provides new numerical insights into vortex dynamics, especially in the fully frustrated case, and compares these with experimental and theoretical results.

Findings

Critical currents agree with previous theories in unfrustrated arrays.

In fully frustrated arrays, results match experimental data but differ from theoretical predictions.

Physical explanations for vortex motion are proposed based on simulation observations.

Abstract

We study numerically the motion of vortices in two-dimensional arrays of resistively shunted Josephson junctions. An extra vortex is created in the ground states by introducing novel boundary conditions and made mobile by applying external currents. We then measure critical currents and the corresponding pinning energy barriers to vortex motion, which in the unfrustrated case agree well with previous theoretical and experimental findings. In the fully frustrated case our results also give good agreement with experimental ones, in sharp contrast with the existing theoretical prediction. A physical explanation is provided in relation with the vortex motion observed in simulations.