Quantum oscillations of rectified dc voltage as a function of magnetic field in an "almost" symmetric superconducting ring

TL;DR

This study observes quantum oscillations in the rectified dc voltage of an almost symmetric superconducting aluminum ring near Tc, revealing fundamental and satellite frequencies influenced by geometry and external parameters.

Contribution

It demonstrates quantum oscillations in a nearly symmetric superconducting ring without intentional asymmetry, highlighting the presence of unexpected satellite frequencies in the Fourier spectra.

Findings

Vdc(B) oscillations are similar to those in asymmetric rings but with smaller amplitude.

Fourier spectra show fundamental and harmonic frequencies related to the ring area.

Satellite frequencies depend on geometry and external parameters.

Abstract

Periodic quantum oscillations of a rectified dc voltage Vdc(B) vs the perpendicular magnetic field B were measured near the critical temperature Tc in a single superconducting aluminum almost symmetric ring (without specially created circular asymmetry) biased by alternating current with a zero dc component. With varying bias current and temperature, these Vdc(B) oscillations behave like the Vdc(B) oscillations observed in a circular-asymmetric ring but are of smaller amplitude. The Fourier spectra of the Vdc(B) functions exhibit a fundamental frequency, corresponding to the ring area, and its higher harmonics. Unexpectedly, satellite frequencies depending on the structure geometry and external parameters were found next to the fundamental frequency and around its higher harmonics.