Effect of aging-induced disorder on the quantum transport properties of few-layer WTe2

Abstract

The emerging physical phenomena found in transition metal dicalcogenides (TMDCs) have triggered vast investigations in recent years. Among them, nanoelectronics in WTe2 devices have attracted particular attentions due to its exotic band structure that leads to exciting phenomena such as the predicted type-II Weyl semimetallic state. However, the thickness dependence of its quantum transport properties in the two-dimensional limit remains under debate. The major missing ingredient in the previous studies is the aging-induced disorder, as atomically thin layers of TMDCs are often known to be metastable in the ambient atmosphere. Here, we show systematic performance of low temperature quantum electronic transport of few-layer WTe2. It is observed that aging-induced localized electronic states explains the low temperature Coulomb gap in transport measurements, leading to the anomalous magnetotransport which appears to be extrinsic. While few-layered WTe2 shows 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, upon further aging, leads to the observation of weak anti-localization. Our study reveals for the first time the correlation between the unusual magnetotransport and disorder in few-layered WTe2, which is indispensable in providing guidance on its future device applications.