Observation of Quantum Anomalous Hall Effect and Exchange Interaction in Topological Insulator/Antiferromagnet Heterostructure

Lei Pan; Alexander Grutter; Peng Zhang; Xiaoyu Che; Tomohiro Nozaki; Alex Stern; Mike Street; Bing Zhang; Brian Casas; Qing Lin He; Eun Sang Choi; Steven M Disseler; Dustin A Gilbert; Gen Yin; Qiming Shao; Peng Deng; Yingying Wu; Xiaoyang Liu; Xufeng Kou; Sahashi Masashi; Xiaodong Han; Christian Binek; Scott Chambers; Jing Xia; Kang L Wang

doi:10.1002/adma.202001460

Observation of Quantum Anomalous Hall Effect and Exchange Interaction in Topological Insulator/Antiferromagnet Heterostructure

Adv Mater. 2020 Aug;32(34):e2001460. doi: 10.1002/adma.202001460. Epub 2020 Jul 21.

Authors

Lei Pan¹, Alexander Grutter², Peng Zhang¹, Xiaoyu Che¹, Tomohiro Nozaki³, Alex Stern⁴, Mike Street⁵, Bing Zhang⁶, Brian Casas⁴, Qing Lin He^{1

7}, Eun Sang Choi⁸, Steven M Disseler², Dustin A Gilbert⁹, Gen Yin¹, Qiming Shao^{1

10}, Peng Deng¹, Yingying Wu¹, Xiaoyang Liu¹¹, Xufeng Kou¹¹, Sahashi Masashi³, Xiaodong Han⁶, Christian Binek⁵, Scott Chambers¹², Jing Xia⁴, Kang L Wang^{1

13

14}

Affiliations

¹ Department of Electrical and Computer Engineering, University of California, Los Angeles, CA, 90095, USA.
² NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD, 20899-6102, USA.
³ Department of Electronic Engineering, Tohoku University, Sendai, 980-8579, Japan.
⁴ Department of Physics and Astronomy, University of California, Irvine, CA, 92697, USA.
⁵ Department of Physics and Astronomy, University of Nebraska, Lincoln, NE, 68588, USA.
⁶ Beijing Key Lab of Microstructure and Property of Advanced Materials, Beijing University of Technology, Beijing, 100124, China.
⁷ International Center for Quantum Materials, School of Physics, Peking University, Beijing, 100871, China.
⁸ National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL, 32310-3706, USA.
⁹ Department of Materials Science, University of Tennessee, Knoxville, TN, 37996, USA.
¹⁰ Department of Electronic and Computer Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR, China.
¹¹ School of Information Science and Technology, ShanghaiTech University, Shanghai, 200031, China.
¹² Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, WA, 99352, USA.
¹³ Department of Materials Science and Engineering, University of California, Los Angeles, CA, 90095, USA.
¹⁴ Department of Physics, University of California, Los Angeles, CA, 90095, USA.

PMID: 32691882
DOI: 10.1002/adma.202001460

Abstract

Integration of a quantum anomalous Hall insulator with a magnetically ordered material provides an additional degree of freedom through which the resulting exotic quantum states can be controlled. Here, an experimental observation is reported of the quantum anomalous Hall effect in a magnetically-doped topological insulator grown on the antiferromagnetic insulator Cr₂ O₃ . The exchange coupling between the two materials is investigated using field-cooling-dependent magnetometry and polarized neutron reflectometry. Both techniques reveal strong interfacial interaction between the antiferromagnetic order of the Cr₂ O₃ and the magnetic topological insulator, manifested as an exchange bias when the sample is field-cooled under an out-of-plane magnetic field, and an exchange spring-like magnetic depth profile when the system is magnetized within the film plane. These results identify antiferromagnetic insulators as suitable candidates for the manipulation of magnetic and topological order in topological insulator films.

Keywords: antiferromagnet; quantum anomalous Hall effect; topological insulators.

Abstract

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