Effect of aging-induced disorder on the quantum transport properties of few-layer WTe2
Effect of aging-induced disorder on the quantum transport properties of few-layer WTe2
复制标题
老化引起的无序对少层WTe2量子输运特性的影响
DOI：
10.1088/2053-1583/4/1/011011
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发表时间：
2017-03-01
期刊：
影响因子：
5.5
通讯作者：
Zhang, Zhi Dong
中科院分区：
文献类型：
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作者：
Liu, Wei Lai;Chen, Mao Lin;Zhang, Zhi Dong
近年来，过渡金属二硫属化合物（TMDC）中的物理现象引起了人们的广泛研究。其中，WTe 2器件中的纳米电子学由于其奇异的能带结构而引起了人们的特别关注，该能带结构导致了诸如预测的II型Weyl半金属态等令人兴奋的现象。然而，其量子输运性质在二维极限的厚度依赖性仍然存在争议。在以前的研究中主要缺少的成分是老化引起的紊乱，因为原子薄层的TMDC通常被认为在环境大气中是亚稳态的。在这里，我们展示了几层WTe2的低温量子电子输运的系统性能。据观察，老化引起的本地化的电子状态解释了低温库仑隙的运输测量，导致异常的磁输运似乎是外在的。虽然几层WTe2在新鲜状态下显示出明显的金属倾向，但降解的器件首先表现出凹入绝缘行为，最后进入完全绝缘状态。相应地，从抛物线到线性磁阻的交叉，并且，在进一步老化时，导致观察到弱反定位。我们的研究首次揭示了在几层WTe 2中不寻常的磁输运和无序之间的相关性，这对于指导其未来的器件应用是不可或缺的。
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.