Temperature-Driven Topological Transition in 1T'-MoTe2

TL;DR

This study demonstrates that a temperature-induced structural phase transition in 1T'-MoTe2 switches its surface states between topological and trivial, confirmed through quasiparticle interference measurements.

Contribution

It reveals the temperature-driven topological transition in 1T'-MoTe2 and links structural changes to surface state topology using quasiparticle interference data.

Findings

Surface states are topologically non-trivial at low temperature.

Surface states become trivial at room temperature.

Temperature acts as a switch for topological surface states.

Abstract

The topology of Weyl semimetals requires the existence of unique surface states. Surface states have been visualized in spectroscopy measurements, but their connection to the topological character of the material remains largely unexplored. 1T'-MoTe2, presents a unique opportunity to study this connection. This material undergoes a phase transition at 240K that changes the structure from orthorhombic (putative Weyl semimetal) to monoclinic (trivial metal), while largely maintaining its bulk electronic structure. Here we show from temperature-dependent quasiparticle interference measurements that this structural transition also acts as a topological switch for surface states in 1T'-MoTe2. At low temperature, we observe strong quasiparticle scattering, consistent with theoretical predictions and photoemission measurements for the surface states in this material. In contrast, measurements performed at room temperature show the complete absence of the scattering wavevectors associated with the trivial surface states. These distinct quasiparticle scattering behaviors show that 1T'-MoTe2 is ideal for separating topological and trivial electronic phenomena via temperature dependent measurements.