MoTe2 is a good match for GeI by preserving quantum spin Hall phase
MoTe2 is a good match for GeI by preserving quantum spin Hall phase
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MoTe2 通过保留量子自旋霍尔相而与 GeI 非常匹配
DOI：
10.1007/s12274-017-1488-4
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发表时间：
2017
期刊：
影响因子：
9.9
通讯作者：
Baibiao Huang
中科院分区：
文献类型：
--
作者：
Xinru Li;Ying Dai;Chengwang Niu;Y;ong Ma;Wei Wei;Baibiao Huang
量子自旋霍尔（QSH）绝缘体是一类新型材料，正在迅速成为凝聚态物理的主流。 QSH绝缘体发展的主要障碍是它们与基底的强相互作用使得它们难以进行实验研究。在这项研究中，我们利用密度泛函理论，发现 MoTe2 与 GeI 单层非常匹配。通过分子动力学模拟检查了范德华 GeI/MoTe2 异质片的热稳定性。模拟扫描隧道显微镜显示，GeI 单层完美地保留了 MoTe2 的块状蜂窝结构。通过直接计算自旋陈数为-1，MoTe2 上的 GeI 被证实保持了其拓扑能带结构，具有 0.24 eV 的相当大的间接体带隙。正如预期的那样，GeI 的电子迁移率因 MoTe2 衬底限制而增强。根据有效质量近似的变形势理论，GeI/MoTe2在300 K时的电子迁移率估计为372.7 cm2·s−1·V−1，比独立式GeI高20倍。我们的研究表明，传统衬底总是会破坏QSH绝缘体的拓扑状态并阻碍电子传输，这为QSH绝缘体在室温下的进一步实现和利用铺平了道路。
Quantum spin Hall (QSH) insulator is a new class of materials that is quickly becoming mainstream in condensed-matter physics. The main obstacle for the development of QSH insulators is that their strong interactions with substrates make them difficult to study experimentally. In this study, using density functional theory, we discovered that MoTe2 is a good match for a GeI monolayer. The thermal stability of a van der Waals GeI/MoTe2 heterosheet was examined via molecular-dynamics simulations. Simulated scanning tunneling microscopy revealed that the GeI monolayer perfectly preserves the bulked honeycomb structure of MoTe2. The GeI on MoTe2 was confirmed to maintain its topological band structure with a sizable indirect bulk bandgap of 0.24 eV by directly calculating the spin Chern number to be −1. As expected, the electron mobility of the GeI is enhanced by MoTe2 substrate restriction. According to deformation-potential theory with the effective-mass approximation, the electron mobility of GeI/MoTe2 was estimated as 372.7 cm2·s−1·V−1 at 300 K, which is 20 times higher than that of freestanding GeI. Our research shows that traditional substrates always destroy the topological states and hinder the electron transport in QSH insulators, and pave way for the further realization and utilization of QSH insulators at room temperature.