Site-dependent Local Spin Susceptibility and Low-energy Excitation in a Weyl Semimetal WTe$_2$

TL;DR

This study uses $^{125}$Te NMR to explore site-dependent spin susceptibility and low-energy excitations in WTe$_2$, revealing Weyl fermion signatures and site-specific electron correlations.

Contribution

It provides the first detailed site-dependent NMR analysis of spin susceptibility and hyperfine interactions in WTe$_2$, linking local electronic structure to Weyl physics.

Findings

Temperature dependence of $1/T_1T$ shows Weyl fermion behavior.

Knight shift scales with $ oot{ }$ of $1/T_1T$, indicating spin contributions.

Site-dependent hyperfine couplings reflect electron correlation variations.

Abstract

Site-dependent local spin susceptibility is investigated with $^{125}$Te nuclear magnetic resonance in a Weyl semimetal WTe$_2$. The nuclear spin-lattice relaxation rate $1/T_1T$ shows a dependence of the square of temperature $T$ at high temperatures, followed by a constant behavior below 50 K. The temperature dependence features Weyl fermions appearing around the linearly crossing bands. The Knight shift $K$ scales to the square root of $1/T_1T$, corroborating a predominant spin contribution in low-lying excitation. The observed dependence of $K$ and $1/T_1T$ on the four Te sites shows the site-dependent electron correlation and density of states. The angular profile of the NMR spectrum gives the anisotropic hyperfine coupling tensor, consistent with $5p$ hole occupations on Te sites.