Probing the low-temperature limit of the quantum anomalous Hall effect

Lei Pan; Xiaoyang Liu; Qing Lin He; Alexander Stern; Gen Yin; Xiaoyu Che; Qiming Shao; Peng Zhang; Peng Deng; Chao-Yao Yang; Brian Casas; Eun Sang Choi; Jing Xia; Xufeng Kou; Kang L Wang

doi:10.1126/sciadv.aaz3595

Probing the low-temperature limit of the quantum anomalous Hall effect

Sci Adv. 2020 Jun 17;6(25):eaaz3595. doi: 10.1126/sciadv.aaz3595. eCollection 2020 Jun.

Authors

Lei Pan¹, Xiaoyang Liu², Qing Lin He^{1

3}, Alexander Stern^{4

5}, Gen Yin¹, Xiaoyu Che¹, Qiming Shao^{1

6}, Peng Zhang¹, Peng Deng¹, Chao-Yao Yang¹, Brian Casas⁴, Eun Sang Choi⁷, Jing Xia⁴, Xufeng Kou², Kang L Wang^{1

8

9}

Affiliations

¹ Department of Electrical and Computer Engineering, University of California, Los Angeles, Los Angeles, CA 90095, USA.
² School of Information Science and Technology, ShanghaiTech University, Shanghai 200031, China.
³ International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China.
⁴ Department of Physics and Astronomy, University of California, Irvine, Irvine, CA 92697, USA.
⁵ Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straße 40, 01187 Dresden, Germany.
⁶ Department of Electronic and Computer Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR, China.
⁷ National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL 32310-3706, USA.
⁸ Department of Materials Science and Engineering, University of California, Los Angeles, Los Angeles, CA 90095, USA.
⁹ Department of Physics, University of California, Los Angeles, Los Angeles, CA 90095, USA.

Abstract

Quantum anomalous Hall effect has been observed in magnetically doped topological insulators. However, full quantization, up until now, is limited within the sub-1 K temperature regime, although the material's magnetic ordering temperature can go beyond 100 K. Here, we study the temperature limiting factors of the effect in Cr-doped (BiSb)₂Te₃ systems using both transport and magneto-optical methods. By deliberate control of the thin-film thickness and doping profile, we revealed that the low occurring temperature of quantum anomalous Hall effect in current material system is a combined result of weak ferromagnetism and trivial band involvement. Our findings may provide important insights into the search for high-temperature quantum anomalous Hall insulator and other topologically related phenomena.

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