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

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 $1/T_{1}T$ 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 $1/T_{1}T$, corroborating a predominant spin contribution in low-lying excitation. The observed dependence of $K$ and $1/T_{1}T$ 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.

6 pages, 5 figures

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