Thermodynamic signatures of short-range magnetic correlations in UTe$_2$

TL;DR

This study investigates the normal state of UTe$_2$, revealing thermodynamic signatures of short-range magnetic correlations and their potential link to unconventional superconductivity, through detailed thermodynamic and transport measurements.

Contribution

It provides new thermodynamic evidence of magnetic correlations in UTe$_2$ and constructs an $H$-$T$ phase diagram similar to ferromagnetic superconductors, highlighting the role of short-range fluctuations.

Findings

Observation of a Schottky-like anomaly around 12K with R ln 2 entropy.

Construction of an $H$-$T$ phase diagram resembling URhGe.

Enhanced Wilson and Korringa ratios indicating short-range ferromagnetic fluctuations.

Abstract

The normal-state out of which unconventional superconductivity in UTe$_2$ emerges is studied in detail using a variety of thermodynamic and transport probes. Clear evidence for a broad Schottky-like anomaly with roughly R ln 2 entropy around $T^{*} \approx 12$K is observed in all measured quantities. Comparison with high magnetic field transport data allows the construction of an $H\text{-}T$ phase diagram resembling that of the ferromagnetic superconductor URhGe. The low field electronic Gr\"uneisen parameter of $T^{*}$ and that of the metamagnetic transition at $H_m \approx 35$T are comparable pointing to a common origin of both phenomena. Enhanced Wilson and Korringa ratios suggests that the existence of short range ferromagnetic fluctuations cannot be ruled out.