High-frequency diode effect in superconducting Nb$_3$Sn micro-bridges

TL;DR

This study demonstrates a superconducting diode effect in Nb$_3$Sn micro-bridges, operating at frequencies up to 100 kHz, with potential for GHz-range applications, driven by vortex dynamics and symmetry breaking.

Contribution

First observation of high-frequency superconducting diode effect in Nb$_3$Sn micro-bridges, supported by finite element modeling and microscopy evidence.

Findings

Diode efficiency peaks at ~10% around 10 mT magnetic field.

Diode effect persists up to 100 kHz frequency.

Resistance during diode operation is halved compared to normal state.

Abstract

The superconducting diode effect has been recently reported in a variety of systems and different symmetry breaking mechanisms have been examined. However, the frequency range of these potentially important devices still remains obscure. We investigated superconducting micro-bridges of Nb$_{3}$Sn in out-of-plane magnetic fields; optimum magnetic fields of $\sim$10 mT generate $\sim $10% diode efficiency, while higher fields of $\sim$15-20 mT quench the effect. The diode changes its polarity with magnetic field reversal. We documented superconductive diode rectification at frequencies up to 100 kHz, the highest reported as of today. Interestingly, the bridge resistance during diode operation reaches a value that is a factor of two smaller than in its normal state, which is compatible with the vortex-caused mechanism of resistivity. This is confirmed by finite element modeling based on time-dependent Ginzburg-Landau equations. To explain experimental findings, no assumption of lattice thermal inequilibrium was required. Dissimilar edges of the superconductor strip can be responsible for the inversion symmetry breaking by vortex penetration barrier; visual evidence of this opportunity was revealed by scanning electron microscopy. Estimates are in favor of much higher (GHz) range of frequencies for this type of diode.