Intrinsic exchange biased anomalous Hall effect in an uncompensated antiferromagnet MnBi2Te4

Su Kong Chong; Yang Cheng; Huiyuan Man; Seng Huat Lee; Yu Wang; Bingqian Dai; Masaki Tanabe; Ting-Hsun Yang; Zhiqiang Mao; Kathryn A Moler; Kang L Wang

doi:10.1038/s41467-024-46689-8

Intrinsic exchange biased anomalous Hall effect in an uncompensated antiferromagnet MnBi₂Te₄

Nat Commun. 2024 Apr 3;15(1):2881. doi: 10.1038/s41467-024-46689-8.

Authors

Su Kong Chong^#¹, Yang Cheng^#², Huiyuan Man^{3

4}, Seng Huat Lee^{5

6}, Yu Wang^{5

6}, Bingqian Dai², Masaki Tanabe², Ting-Hsun Yang², Zhiqiang Mao^{5

6}, Kathryn A Moler^{3

7

8}, Kang L Wang⁹

Affiliations

¹ Department of Electrical and Computer Engineering, University of California, Los Angeles, CA, 90095, USA. sukongc@g.ucla.edu.
² Department of Electrical and Computer Engineering, University of California, Los Angeles, CA, 90095, USA.
³ Geballe Laboratory for Advanced Materials, Stanford University, Stanford, CA, 94305, USA.
⁴ Stanford Nano Shared Facilities, Stanford University, Stanford, CA, 94305, USA.
⁵ 2D Crystal Consortium, Materials Research Institute, The Pennsylvania State University, University Park, PA, 16802, USA.
⁶ Department of Physics, The Pennsylvania State University, University Park, PA, 16802, USA.
⁷ Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA.
⁸ Department of Physics and Applied Physics, Stanford University, Stanford, CA, 94305, USA.
⁹ Department of Electrical and Computer Engineering, University of California, Los Angeles, CA, 90095, USA. wang@seas.ucla.edu.

^# Contributed equally.

Abstract

Achieving spin-pinning at the interface of hetero-bilayer ferromagnet/antiferromagnet structures in conventional exchange bias systems can be challenging due to difficulties in interface control and the weakening of spin-pinning caused by poor interface quality. In this work, we propose an alternative approach to stabilize the exchange interaction at the interface of an uncompensated antiferromagnet by utilizing a gradient of interlayer exchange coupling. We demonstrate this exchange interaction through a designed field training protocol in the odd-layer topological antiferromagnet MnBi₂Te₄. Our results reveal a remarkable field-trained exchange bias of up to ~ 400 mT, which exhibits high repeatability and can be easily reset by a large training field. Notably, this field-trained exchange bias effect persists even with zero-field initialization, presenting a stark contrast to the traditional field-cooled exchange bias. The highly tunable exchange bias observed in this single antiferromagnet compound, without the need for an additional magnetic layer, provides valuable insight into the exchange interaction mechanism. These findings pave the way for the systematic design of topological antiferromagnetic spintronics.

Abstract

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