Effect of aging-induced disorder on the quantum transport properties of atomically thin WTe$_{2}$

TL;DR

This study investigates how aging-induced disorder affects the quantum transport properties of atomically thin WTe₂, revealing a transition from metallic to insulating behavior linked to structural degradation.

Contribution

It provides the first detailed correlation between disorder and magnetotransport phenomena in few-layered WTe₂, advancing understanding of its stability and electronic properties.

Findings

Degradation causes a transition from metallic to insulating behavior.

Magnetoresistance evolves from parabolic to weak anti-localization.

Structural analysis confirms formation of amorphous islands and localized states.

Abstract

Atomically thin layers of transition-metal dicalcogenides (TMDCs) are often known to be metastable in the ambient atmosphere. Understanding the mechanism of degradation is essential for their future applications in nanoelectronics, and thus has attracted intensive interest recently. Here, we demonstrate a systematic study of atomically thin WTe$_{2}$ in its low temperature quantum electronic transport properties. Strikingly, while the temperature dependence of few layered WTe$_{2}$ showed clear metallic tendency in the fresh state, degraded devices first exhibited a re-entrant insulating behavior, and finally entered a fully insulating state. Correspondingly, a crossover from parabolic to linear magnetoresistance, and finally to weak anti-localization was seen. Real-time Raman scattering measurement, together with transmission electron microscopy studies done before and after air degradation of atomically thin WTe$_{2}$ further confirmed that the material gradually form amorphous islands. It thus leads to localized electronic states and explains the low temperature Coulomb gap observed in transport measurements. Our study reveals for the first time the correlation between the unusual magnetotransport and disorder in few-layered WTe$_{2}$, which is indispensable in providing guidance on its future devices application.