Quenched randomness, thermal fluctuations and reentrant superconductivity: application to UTe$_2$

TL;DR

This paper proposes a phenomenological model explaining reentrant superconductivity in UTe$_2$ through quenched randomness and enhanced fluctuations, accounting for experimental observations of broadened transitions and reentrant behavior.

Contribution

It introduces a new phenomenological framework linking quenched disorder and fluctuations to reentrant superconductivity in UTe$_2$, emphasizing the role of inhomogeneity.

Findings

Quenched randomness can induce reentrant superconductivity.

Superconducting fluctuations are enhanced near the transition.

Inhomogeneity explains broadened superconducting transitions.

Abstract

Reentrant superconductivity has been observed in the candidate spin-triplet superconductor UTe$_2$ as a function of the magnetic field applied along the hard axis. Resistivity measurements have shown, a broadened superconducting transition appears near the minimal $T_c$, highlighting the importance of superconducting fluctuations in this regime. We present a phenomenological study assuming a field-driven first-order transition between two superconducting states. We show that with quenched randomness, inhomogeneity-enhanced superconducting fluctuations near the transition could naturally account for both the reentrant superconductivity as well as the broadened superconducting transition.