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

We report on the findings of simulations and experiments of vortex states in superconducting microwires with periodic rectangular pinhole structures. The simulations are 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 first observe a vortex-free Meissner state, followed by a resistive vortex-flow mixed state and a state with a more intricate vortex pattern. The resulting dependence of the critical current I c on magnetic field exhibits two plateaus with distinctly different vortex dynamics. Corresponding experimentally measured magnetic field dependences of I c of WSi microwires with periodic pinhole structures and varying hole spacing confirm 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 smaller pinhole spacings, in agreement with the results of TDGL simulations. The good agreement of the simulations with the experimental observations presents a convenient strategy for the optimization of single-photon detectors with or without artificial and natural defects.