State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China.
High Field Magnet Laboratory (HFML-EMFL), Radboud University, Toernooiveld 7, Nijmegen 6525 ED, Netherlands.
Phys Rev Lett. 2019 Jan 25;122(3):036602. doi: 10.1103/PhysRevLett.122.036602.
The quantum Hall effect (QHE) in a 3D Dirac semimetal thin film is attributed to either the quantum confinement induced bulk subbands or the Weyl orbits that connect the opposite surfaces via bulk Weyl nodes. However, it is still unknown whether the QHE based on the Weyl orbit can survive as the bulk Weyl nodes are gapped. Moreover, there are closed Fermi loops rather than open Fermi arcs on the Dirac semimetal surface, which can also host the QHE. Here we report the QHE in the 3D Dirac semimetal Cd_{3}As_{2} nanoplate by tuning the gate voltage under a fixed 30 T magnetic field. The quantized Hall plateaus at odd filling factors are observed as a magnetic field along the [001] crystal direction, indicating a Berry's phase π from the topological surface states. Furthermore, even filling factors are observed when the magnetic field is along the [112] direction, indicating the C_{4} rotational symmetry breaking and a topological phase transition. The results shed light on the understanding of QHE in 3D Cd_{3}As_{2}.
三维狄拉克半金属薄膜中的量子霍尔效应（QHE）归因于量子限制诱导的体子带或连接体子 Wey 节点的 Weyl 轨道。然而，基于 Weyl 轨道的 QHE 是否能在体子 Wey 节点被能隙化的情况下仍然未知。此外，狄拉克半金属表面上存在封闭的费米环而不是开放的费米弧，这也可以承载 QHE。在这里，我们通过在固定的 30 T 磁场下调节栅极电压，在三维狄拉克半金属 Cd_3As_2 纳米片中报告了 QHE。当磁场沿 [001] 晶体方向时，观察到奇数填充因子的量子霍尔平台，表明来自拓扑表面态的 Berry 相π。此外，当磁场沿 [112] 方向时，观察到偶数填充因子，表明 C_4 旋转对称破缺和拓扑相变。这些结果有助于理解三维 Cd_3As_2 中的 QHE。
