Fluctuations of the superconducting order parameter as an origin of the Nernst effect

TL;DR

This paper explains the large Nernst effect observed in amorphous superconducting films above the critical temperature as arising from fluctuations in the superconducting order parameter, supported by theoretical and experimental agreement.

Contribution

It introduces a theoretical framework linking superconducting order parameter fluctuations to the Nernst effect, aligning with experimental data and discussing thermodynamic constraints.

Findings

Strong Nernst signal explained by order parameter fluctuations

Theoretical calculations match experimental data across conditions

Thermodynamic constraints limit the Nernst effect magnitude

Abstract

We show that the strong Nernst signal observed recently in amorphous superconducting films far above the critical temperature is caused by the fluctuations of the superconducting order parameter. We demonstrate a striking agreement between our theoretical calculations and the experimental data at various temperatures and magnetic fields. Besides, the Nernst effect is interesting not only in the context of superconductivity. We discuss some subtle issues in the theoretical study of thermal phenomena that we have encountered while calculating the Nernst coefficient. In particular, we explain how the Nernst theorem (the third law of thermodynamics) imposes a strict constraint on the magnitude of the Nernst effect.