Liu Chang, Wang Yongchao, Li Hao, Wu Yang, Li Yaoxin, Li Jiaheng, He Ke, Xu Yong, Zhang Jinsong, Wang Yayu
State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing, China.
Beijing Innovation Center for Future Chips, Tsinghua University, Beijing, China.
Nat Mater. 2020 May;19(5):522-527. doi: 10.1038/s41563-019-0573-3. Epub 2020 Jan 6.
The intricate interplay between non-trivial topology and magnetism in two-dimensional materials can lead to the emergence of interesting phenomena such as the quantum anomalous Hall effect. Here we investigate the quantum transport of both bulk crystal and exfoliated MnBiTe flakes in a field-effect transistor geometry. For the six septuple-layer device tuned into the insulating regime, we observe a large longitudinal resistance and zero Hall plateau, which are characteristics of an axion insulator state. The robust axion insulator state occurs in zero magnetic field, over a wide magnetic-field range and at relatively high temperatures. Moreover, a moderate magnetic field drives a quantum phase transition from the axion insulator phase to a Chern insulator phase with zero longitudinal resistance and quantized Hall resistance h/e, where h is Planck's constant and e is electron charge. Our results pave the way for using even-number septuple-layer MnBiTe to realize the quantized topological magnetoelectric effect and axion electrodynamics in condensed matter systems.
二维材料中不平凡的拓扑结构与磁性之间复杂的相互作用可导致诸如量子反常霍尔效应等有趣现象的出现。在此，我们研究了体晶体和剥离的MnBiTe薄片在场效应晶体管几何结构中的量子输运。对于调制成绝缘态的六层七层堆叠器件，我们观察到较大的纵向电阻和零霍尔平台，这是轴子绝缘体态的特征。稳健的轴子绝缘体态出现在零磁场、宽磁场范围以及相对较高温度下。此外，适度的磁场驱动量子相变，从轴子绝缘相转变为具有零纵向电阻和量子化霍尔电阻h/e的陈绝缘相，其中h是普朗克常数，e是电子电荷。我们的结果为利用偶数层七层堆叠的MnBiTe在凝聚态系统中实现量子化拓扑磁电效应和轴子电动力学铺平了道路。
