Edge superconducting state in Nb thin film with rectangular arrays of antidots

TL;DR

This study investigates the behavior of superconducting Nb thin films with rectangular antidot arrays, revealing edge superconducting states and vortex dynamics through transport measurements across various magnetic fields.

Contribution

It uncovers the existence of edge superconducting states and vortex sublattices in Nb films with antidots, highlighting a crossover in vortex behavior at high magnetic fields.

Findings

Magnetoresistance dips at rational flux quanta indicate a wire network regime.

Interstitial vortices form sublattices at higher fields.

Edge superconducting states influence oscillation periods.

Abstract

Superconducting Nb thin films with rectangular arrays of submicron antidots have been systemically investigated by transport measurements. In low fields, the magnetoresistance curves demonstrate well-defined dips at integral and rational numbers of flux quanta per unit cell, which corresponds to a superconducting wire network-like regime. When the magnetic field is higher than a saturation field, interstitial vortices interrupt the collective oscillation in low fields and form vortex sublattice, where a larger magnetic field interval is observed. In higher fields, a crossover behavior from the interstitial sublattice state to a single-loop-like state is observed, characterized by oscillations with a period of $\Phi_0/\pi r_{eff}^2$, originating from the existence of edge superconducting states with a size $r_{eff}$ around the antidots.