Dirac electron behavior and NMR evidence for topological band inversion in ZrTe5

TL;DR

This study uses NMR measurements and theoretical modeling to reveal temperature-dependent topological phase transitions and band inversion in ZrTe$_5$, identifying a Lifshitz transition and Dirac semimetal state.

Contribution

It provides experimental NMR evidence for topological phase transition and band inversion in ZrTe$_5$, supported by electronic structure calculations.

Findings

Identification of a Lifshitz transition at 85 K

Observation of a temperature-dependent topological phase change

Direct NMR evidence of band inversion

Abstract

We report $^{125}$Te NMR measurements of the topological quantum material ZrTe$_5$. Spin-lattice relaxation results, well-explained by a theoretical model of Dirac electron systems, reveal that the topological characteristic of ZrTe$_5$ is $T$-dependent, changing from weak topological insulator to strong topological insulator as temperature increases. Electronic structure calculations confirm this ordering, the reverse of what has been proposed. NMR results demonstrate a gapless Dirac semimetal state occurring at a Lifshitz transition temperature, $T_c=85$ K in our crystals. We demonstrate that the changes in NMR shift at $T_c$ also provide direct evidence of band inversion when the topological phase transition occurs.