Higher harmonic resistance oscillations in micro-bridge superconducting Nb ring

TL;DR

This study investigates resistance oscillations in superconducting Nb rings, revealing fundamental h/2e oscillations in simple rings and higher harmonics in micro-bridge configurations, even at larger device sizes.

Contribution

It demonstrates the occurrence of higher harmonic resistance oscillations in micro-bridge Nb rings, expanding understanding of quantum interference effects in larger superconducting devices.

Findings

Clear h/2e resistance oscillations in simple rings

Higher harmonic oscillations in micro-bridge rings with tuned current

Detection of higher harmonics despite larger device size

Abstract

We studied resistance oscillations in two types of superconducting mesoscopic Nb rings. In a simple superconducting ring device, a resistance oscillation with a period of the quantized magnetic flux h/2e was clearly observed. On the other hand, in a micro-bridge ring device where two-narrow parts are embedded in parallel and work as superconductor-normal metal-superconductor junctions, higher harmonic resistance oscillations were obtained when the measurement current was well-tuned. We argue that such higher harmonic resistance oscillations can be detected even in the micro-bridge Nb superconducting ring device where the device size is much larger than the coherence length of Nb.