Quantum Hall effect of Weyl fermions in n-type semiconducting tellurene
Quantum Hall effect of Weyl fermions in n-type semiconducting tellurene
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DOI：
10.1038/s41565-020-0715-4
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发表时间：
2020-06-29
影响因子：
38.3
通讯作者：
Ye, Peide D.
中科院分区：
文献类型：
--
作者：
Qiu, Gang;Niu, Chang;Ye, Peide D.
狄拉克和韦尔节点材料可以容纳低能量相对论准粒子。在强磁场下，可以通过量子霍尔态直接观察Dirac/Weyl材料的拓扑性质。然而，大多数狄拉克/韦尔节点通常存在于半金属中，由于其偶然的带交叉起源而没有可利用的带隙。在这里，我们报告了半导体中外尔费米子的首次实验观察。碲烯是碲的二维形式，具有手性晶体结构，可在导带边缘附近产生具有刺猬状径向自旋结构的非常规韦尔节点。我们通过水热法和随后的介电掺杂合成了高质量的 n 型碲烯，并在量子霍尔序列中检测到了拓扑上非平凡的 pi Berry 相。我们的工作将外尔物质的范围扩展到半导体，并通过将拓扑材料的优点与多功能半导体相结合，提供了设计新型量子器件的新平台。外尔节点的意外带交叉起源加上不存在相当大的带隙，阻碍了外尔半金属中低能相对论准粒子的开发。在门可调的高质量碲烯薄膜中，量子霍尔测量揭示了由这些碲二维片中非常规的韦尔节点引起的拓扑上非平凡的 pi Berry 相。
Dirac and Weyl nodal materials can host low-energy relativistic quasiparticles. Under strong magnetic fields, the topological properties of Dirac/Weyl materials can directly be observed through quantum Hall states. However, most Dirac/Weyl nodes generically exist in semimetals without exploitable band gaps due to their accidental band-crossing origin. Here, we report the first experimental observation of Weyl fermions in a semiconductor. Tellurene, the two-dimensional form of tellurium, possesses a chiral crystal structure which induces unconventional Weyl nodes with a hedgehog-like radial spin texture near the conduction band edge. We synthesize high-quality n-type tellurene by a hydrothermal method with subsequent dielectric doping and detect a topologically non-trivial pi Berry phase in quantum Hall sequences. Our work expands the spectrum of Weyl matter into semiconductors and offers a new platform to design novel quantum devices by marrying the advantages of topological materials to versatile semiconductors.The accidental band-crossing origin of Weyl nodes paired with the absence of sizeable band gaps hampers the exploitation of low-energy relativistic quasiparticles in Weyl semimetals. In a gate-tunable high-quality tellurene film, quantum Hall measurements unveil a topologically non-trivial pi Berry phase caused by unconventional Weyl nodes in these tellurium two-dimensional sheets.