Flux-induced Nernst effect in a superconducting loop

Abstract

When a superconducting ring encloses a magnetic flux that is not an integer multiple of half the quantum of flux, a voltage arises in the direction perpendicular to the temperature gradient. This effect is entirely due to thermal fluctuations. We study the dependence of this voltage on the temperature gradient, flux, position, average temperature, BCS coherence length, thermal coherence length, and the Kramer--Watts-Tobin parameter. The largest voltages were obtained for fluxes close to $0.3\Phi_0$, average temperatures slightly below the critical temperature, thermal coherence length of the order of the perimeter of the ring and BCS coherence length that is not negligible in comparison to the thermal coherence length. As a rough comparison between the flux-induced and the field-induced effects, we also considered a two dimensional sample.