Layer Hall effect in a 2D topological Axion antiferromagnet
| Autor: | Gao, Anyuan, Liu, Yu-Fei, Hu, Chaowei, Qiu, Jian-Xiang, Tzschaschel, Christian, Ghosh, Barun, Ho, Sheng-Chin, Bérubé, Damien, Chen, Rui, Sun, Haipeng, Zhang, Zhaowei, Zhang, Xin-Yue, Wang, Yu-Xuan, Wang, Naizhou, Huang, Zumeng, Felser, Claudia, Agarwal, Amit, Ding, Thomas, Tien, Hung-Ju, Akey, Austin, Gardener, Jules, Singh, Bahadur, Watanabe, Kenji, Taniguchi, Takashi, Burch, Kenneth S., Bell, David C., Zhou, Brian B., Gao, Weibo, Lu, Hai-Zhou, Bansil, Arun, Lin, Hsin, Chang, Tay-Rong, Fu, Liang, Ma, Qiong, Ni, Ni, Xu, Su-Yang |
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| Rok vydání: | 2021 |
| Předmět: | |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1038/s41586-021-03679-w |
| Popis: | While ferromagnets have been known and exploited for millennia, antiferromagnets (AFMs) were only discovered in the 1930s. The elusive nature indicates AFMs' unique properties: At large scale, due to the absence of global magnetization, AFMs may appear to behave like any non-magnetic material; However, such a seemingly mundane macroscopic magnetic property is highly nontrivial at microscopic level, where opposite spin alignment within the AFM unit cell forms a rich internal structure. In topological AFMs, such an internal structure leads to a new possibility, where topology and Berry phase can acquire distinct spatial textures. Here, we study this exciting possibility in an AFM Axion insulator, even-layered MnBi$_2$Te$_4$ flakes, where spatial degrees of freedom correspond to different layers. Remarkably, we report the observation of a new type of Hall effect, the layer Hall effect, where electrons from the top and bottom layers spontaneously deflect in opposite directions. Specifically, under no net electric field, even-layered MnBi$_2$Te$_4$ shows no anomalous Hall effect (AHE); However, applying an electric field isolates the response from one layer and leads to the surprising emergence of a large layer-polarized AHE (~50%$\frac{e^2}{h}$). Such a layer Hall effect uncovers a highly rare layer-locked Berry curvature, which serves as a unique character of the space-time $\mathcal{PT}$-symmetric AFM topological insulator state. Moreover, we found that the layer-locked Berry curvature can be manipulated by the Axion field, E$\cdot$B, which drives the system between the opposite AFM states. Our results achieve previously unavailable pathways to detect and manipulate the rich internal spatial structure of fully-compensated topological AFMs. The layer-locked Berry curvature represents a first step towards spatial engineering of Berry phase, such as through layer-specific moir\'e potential. Comment: A revised version of this article is published in Nature |
| Databáze: | arXiv |
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