Electronic Evidence of Temperature-Induced Lifshitz Transition and Topological Nature in ZrTe5

TL;DR

This study uses high-resolution photoemission to reveal a temperature-induced Lifshitz transition in ZrTe5, shedding light on its complex topological nature and explaining its resistivity anomaly around 135 K.

Contribution

It provides direct electronic evidence of a temperature-driven Lifshitz transition in ZrTe5 and discusses its implications for the material's topological phase and transport properties.

Findings

Observation of a temperature-dependent evolution from p-type to n-type semimetal.

Identification of a persistent energy gap between nearly-linear bands down to 2 K.

Correlation of the Lifshitz transition with the resistivity peak at 135 K.

Abstract

The topological materials have attracted much attention recently. While three-dimensional topological insulators are becoming abundant, two-dimensional topological insulators remain rare, particularly in natural materials. ZrTe5 has host a long-standing puzzle on its anomalous transport properties; its underlying origin remains elusive. Lately, ZrTe5 has ignited renewed interest because it is predicted that single-layer ZrTe5 is a two-dimensional topological insulator and there is possibly a topological phase transition in bulk ZrTe5. However, the topological nature of ZrTe5 is under debate as some experiments point to its being a three-dimensional or quasi-two-dimensional Dirac semimetal. Here we report high-resolution laser-based angle-resolved photoemission measurements on ZrTe5. The electronic property of ZrTe5 is dominated by two branches of nearly-linear-dispersion bands at the Brillouin zone center. These two bands are separated by an energy gap that decreases with decreasing temperature but persists down to the lowest temperature we measured (~2 K). The overall electronic structure exhibits a dramatic temperature dependence; it evolves from a p-type semimetal with a hole-like Fermi pocket at high temperature, to a semiconductor around ~135 K where its resistivity exhibits a peak, to an n-type semimetal with an electron-like Fermi pocket at low temperature. These results indicate a clear electronic evidence of the temperature-induced Lifshitz transition in ZrTe5. They provide a natural understanding on the underlying origin of the resistivity anomaly at ~135 K and its associated reversal of the charge carrier type. Our observations also provide key information on deciphering the topological nature of ZrTe5 and possible temperature-induced topological phase transition.