NMR investigations of nodal-line semimetal ZrSiTe

In this work, we have applied ¹²⁵Te nuclear magnetic resonance (NMR) spectroscopy combined with density functional theory (DFT) to characterize the electronic structure of a single crystal sample of ZrSiTe. Both the NMR shift and the spin-lattice relaxation rate (1/T₁) clearly show minima at 20 K. The observed T-dependence corresponds to the chemical potential crossing an ungapped 2D Dirac nodal line, which corresponds to the symmetry-protected R-X nodal line in ZrSiTe. From the orientation dependence we show that diamagnetism of electrons along this nodal line dominates the low-T shifts, and the results indicate very small or zero nodal line energy dispersion. 1/T₁ is also dominated by these carriers, with the results agreeing with a model for fluctuating local fields due to very high mobility quasi-2D Dirac electrons. At higher temperatures, additional extrema reflect the topology of the bands connecting the protected node to the network of nodal loops in ZrSiTe, and these provide direct evidence of temperature-driven Lifshitz transitions.