Slow Electronic Dynamics in the Paramagnetic State of UTe$_2$

TL;DR

This study uses $^{125}$Te NMR to reveal slow electronic fluctuations and growing correlations in UTe$_2$'s paramagnetic state, influenced by disorder and near an electronic phase boundary.

Contribution

It provides new insights into the slow electronic dynamics and inhomogeneous states in UTe$_2$, highlighting the role of disorder and proximity to phase instability.

Findings

Slow electronic fluctuations develop below 30-40 K.

Disorder induces inhomogeneous electronic states at low temperatures.

UTe$_2$ is near an electronic phase boundary with potential magnetic or Fermi-surface instabilities.

Abstract

$^{125}$Te NMR experiments in field ($H$) applied along the easy magnetization axis (the $a$-axis) revealed slow electronic dynamics developing in the paramagnetic state of UTe$_2$. The observed slow fluctuations are concerned with a successive growth of long-range electronic correlations below 30$-$40 K, where the spin susceptibility along the hard magnetization axis (the $b$-axis) shows a broad maximum. The experiments also imply that tiny amounts of disorder or defects locally disturb the long-range electronic correlations and develop an inhomogeneous electronic state at low temperatures, leading to a low temperature upturn observed in the bulk-susceptibility in $H\|a$. We suggest that UTe$_2$ would be located on the paramagnetic side near an electronic phase boundary, where either magnetic or Fermi-surface instability would be the origin of the characteristic fluctuations.