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

We report 125Te NMR measurements of the topological quantum material ZrTe5. Spin-lattice relaxation results, well explained by a theoretical model of Dirac electron systems, reveal that the topological characteristic of ZrTe5 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, Tc=85 K, in our crystals. We demonstrate that the changes in NMR shift at Tc also provide direct evidence of band inversion when the topological phase transition occurs.

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