文章基本信息

标题：Origin of extremely large magnetoresistance in the candidate type-II Weyl semimetal MoTe2−x
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作者：Sangyun Lee ; Jaekyung Jang ; Sung-Il Kim 等
期刊名称：Scientific Reports
电子版ISSN：2045-2322
出版年度：2018
卷号：8
期号：1
页码：13937
DOI：10.1038/s41598-018-32387-1
语种：English
出版社：Springer Nature
摘要：The recent observation of extremely large magnetoresistance (MR) in the transition-metal dichalcogenide MoTe₂ has attracted considerable interest due to its potential technological applications as well as its relationship with novel electronic states predicted for a candidate type-II Weyl semimetal. In order to understand the origin of the MR, the electronic structure of MoTe_{2− x} ( x = 0.08) is systematically tuned by application of pressure and probed via its Hall and longitudinal conductivities. With increasing pressure, a monoclinic-to-orthorhombic (1 T′ to T_d) structural phase transition temperature ( T *) gradually decreases from 210 K at 1 bar to 58 K at 1.1 GPa, and there is no anomaly associated with the phase transition at 1.4 GPa, indicating that a T = 0 K quantum phase transition occurs at a critical pressure ( P _c) between 1.1 and 1.4 GPa. The large MR observed at 1 bar is suppressed with increasing pressure and is almost saturated at 100% for P > P _c. The dependence on magnetic field of the Hall and longitudinal conductivities of MoTe_{2− x} shows that a pair of electron and hole bands are important in the low-pressure T_d phase, while another pair of electron and hole bands are additionally required in the high-pressure 1 T′ phase. The MR peaks at a characteristic hole-to-electron concentration ratio ( n _c) and is sharply suppressed when the ratio deviates from n _c within the T_d phase. These results establish the comprehensive temperature-pressure phase diagram of MoTe_{2− x} and underscore that its MR originates from balanced electron-hole carrier concentrations.