# 125Te-NMR Study on a Single Crystal of Heavy Fermion Superconductor UTe2

## TL;DR

This study uses 125Te-NMR to investigate the magnetic properties of UTe2, revealing Ising anisotropy and low-temperature magnetic fluctuations along the easy axis in this heavy fermion superconductor.

## Contribution

It provides the first NMR analysis of UTe2, demonstrating anisotropic susceptibilities and magnetic fluctuations near the superconducting transition.

## Key findings

- Moderate Ising anisotropy in static and dynamical susceptibilities.
- Sudden loss of NMR signal below 20 K along the easy axis.
- Development of low-frequency magnetic fluctuations below 20 K.

## Abstract

We report 125Te-NMR studies on a newly discovered heavy fermion superconductor UTe2. Using a single crystal, we have measured the 125Te-NMR Knight shift K and spin-lattice relaxation rate 1/T1 for fields along the three orthorhombic crystal axes. The data confirm a moderate Ising anisotropy for both the static (K) and dynamical susceptibilities (1/T1) in the paramagnetic state above about 20 K. Around 20 K, however, we have observed a sudden loss of NMR spin-echo signal due to sudden enhancement of the NMR spin-spin relaxation rate 1/T2, when the field is applied along the easy axis of magnetization (=a axis). This behavior suggests the development of longitudinal magnetic fluctuations along the a axis at very low frequencies below 20 K.