Thermal stability study of Weyl semimetal WTe2 by polarized micro-Raman scattering

Abstract

Weyl semimetal Td-phase WTe2, a novel topological matter, possesses non-trivial band structures with strong spin-orbit coupling and thus exhibits a pronounced charge-to-spin conversion efficiency, holding promises as a superior spin current source for spin memory and logic devices. Good thermal stability of WTe2 is crucial for device fabrication and performance, which should be compatible with the semiconductor technology usually involving high temperature process of ∼350–400 °C. However, the thermal stability of this novel material has not been very clear yet. Here, we study the exfoliated Td-WTe2 flakes by in-situ polarized micro-Raman scattering with a much higher heating temperature up to 550 °C. We find that the structure and composition of WTe2 flakes can remain unchanged up to 425 °C. However, around 450 °C, the composition of WTe2 flakes starts to change due to the decomposition and sublimation of Te atoms in WTe2. Our study demonstrates that Weyl semimetal WTe2 shows good thermal stability and has great potentials for the energy-efficient spintronic device application.