Magnetic-field dependent vortex dynamics and critical currents in superconducting microwires with regular large-area perforation by pinholes

Abstract

We report on results of simulations and experiments of vortex states in superconducting micro-wires with periodic rectangular pinhole structures. The simulations have been performed by means of numerically solving the time-dependent Ginzburg-Landau (TDGL) equations. With increasing bias current and for different values of the external magnetic field applied normal to the structure plane, we observe at first a vortex free Meissner state, followed by a resistive vortex-flow mixed state and a state with a more complex vortex pattern. The resulting dependence of the critical current Ic on magnetic field exhibits two plateaus with distinctly different vortex dynamics. Corresponding experimentally measured magnetic-field dependences of Ic of WSi microwires with periodic pinhole structures and varying hole spacing confirmed the predictions of these simulations, showing two ranges of magnetic field with almost field-independent critical currents. The experimentally determined critical currents are larger for a smaller pinhole spacing, in agreement with the results of the TDGL simulations. The good agreement of the simulations with the experimental results provides a convenient strategy for the optimization of single-photon detectors with or without artificial and natural defects.