Layer Hall effect in a 2D topological axion antiferromagnet
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- Harvard Univ., Cambridge, MA (United States)
- Univ. of California, Los Angeles, CA (United States)
- Indian Inst. of Technology, Kanpur (India); Northeastern Univ., Boston, MA (United States)
- Southern Univ. of Science and Technology (SUSTech), Shenzhen (China)
- Nanyang Technological Univ. (Singapore)
- Boston College, Chestnut Hill, MA (United States)
- Max Planck Inst. for Chemical Physics of Solids, Dresden (Germany)
- Indian Inst. of Technology, Kanpur (India)
- National Cheng Kung Univ., Tainan (Taiwan)
- Tata Inst. of Fundamental Research, Mumbai (India)
- National Inst. for Materials Science, Tsukuba (Japan)
- Northeastern Univ., Boston, MA (United States)
- Academia Sinica, Taipei (Taiwan)
- National Cheng Kung Univ., Tainan (Taiwan); Center for Quantum Frontiers of Research and Technology (QFort), Tainan (Taiwan); National Taiwan Univ., Taipei (Taiwan)
- Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
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 MnBi2Te4 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 MnBi2Te4 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 (~50e2/h). Such a layer Hall effect uncovers a highly rare layer-locked Berry curvature, which serves as a unique character of the space-time PT-symmetric AFM topological insulator state. Moreover, we found that the layer-locked Berry curvature can be manipulated by the Axion field, E∙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 moiré potential.
- Research Organization:
- Univ. of California, Los Angeles, CA (United States); Ames Laboratory (AMES), Ames, IA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES)
- Grant/Contract Number:
- SC0021117; AC02-07CH11358
- OSTI ID:
- 1830792
- Alternate ID(s):
- OSTI ID: 1992707
- Journal Information:
- Nature (London), Vol. 595, Issue 7868; ISSN 0028-0836
- Publisher:
- Nature Publishing GroupCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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