Temperature induced Lifshitz transition in WTe2

TL;DR

This study reveals a temperature-induced Lifshitz transition in WTe2, where hole pockets disappear at higher temperatures, significantly affecting its electronic and transport properties.

Contribution

The paper demonstrates the first observation of a temperature-induced Lifshitz transition in WTe2 using ARPES and transport measurements, highlighting temperature's role in electronic structure changes.

Findings

Hole pockets sink below the chemical potential with increasing temperature.

Temperature induces a Lifshitz transition in WTe2.

Transport properties are explained by changes in the Fermi surface.

Abstract

We use ultra-high resolution, tunable, VUV laser-based, angle-resolved photoemission spectroscopy (ARPES) and temperature and field dependent resistivity and thermoelectric power (TEP) measurements to study the electronic properties of WTe2, a compound that manifests exceptionally large, temperature dependent magnetoresistance. The temperature dependence of the TEP shows a change of slope at T=175 K and the Kohler rule breaks down above 70-140 K range. The Fermi surface consists of two electron pockets and two pairs of hole pockets along the X-Gamma-X direction. Upon increase of temperature from 40K, the hole pockets gradually sink below the chemical potential. Like BaFe2As2, WTe2 has clear and substantial changes in its Fermi surface driven by modest changes in temperature. In WTe2, this leads to a rare example of temperature induced Lifshitz transition, associated with the complete disappearance of the hole pockets. These dramatic changes of the electronic structure naturally explain unusual features of the transport data.