Giant nonlocal edge conduction in the axion insulator state of MnBi2Te4

Yaoxin Li; Chang Liu; Yongchao Wang; Zichen Lian; Shuai Li; Hao Li; Yang Wu; Hai-Zhou Lu; Jinsong Zhang; Yayu Wang

doi:10.1016/j.scib.2023.05.011

Giant nonlocal edge conduction in the axion insulator state of MnBi₂Te₄

Sci Bull (Beijing). 2023 Jun 30;68(12):1252-1258. doi: 10.1016/j.scib.2023.05.011. Epub 2023 May 12.

Authors

Yaoxin Li¹, Chang Liu², Yongchao Wang¹, Zichen Lian¹, Shuai Li³, Hao Li⁴, Yang Wu⁵, Hai-Zhou Lu⁶, Jinsong Zhang⁷, Yayu Wang⁸

Affiliations

¹ State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China.
² State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China; Beijing Academy of Quantum Information Sciences, Beijing 100193, China; Beijing Key Laboratory of Opto-electronic Functional Materials & Micro-Nano Devices, Department of Physics, Renmin University of China, Beijing 100872, China; Key Laboratory of Quantum State Construction and Manipulation (Ministry of Education), Renmin University of China, Beijing 100872, China.
³ Shenzhen Institute for Quantum Science and Engineering and Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China; Shenzhen Key Laboratory of Quantum Science and Engineering, Shenzhen 518055, China; Quantum Science Center of Guangdong-Hong Kong-Macao Greater Bay Area (Guangdong), Shenzhen 518045, China; International Quantum Academy, Shenzhen 518048, China.
⁴ School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China; Tsinghua-Foxconn Nanotechnology Research Center, Department of Physics, Tsinghua University, Beijing 100084, China.
⁵ Tsinghua-Foxconn Nanotechnology Research Center, Department of Physics, Tsinghua University, Beijing 100084, China; College of Science, Beijing University of Chemical Technology, Beijing 100029, China.
⁶ Shenzhen Institute for Quantum Science and Engineering and Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China; Shenzhen Key Laboratory of Quantum Science and Engineering, Shenzhen 518055, China; Quantum Science Center of Guangdong-Hong Kong-Macao Greater Bay Area (Guangdong), Shenzhen 518045, China; International Quantum Academy, Shenzhen 518048, China. Electronic address: luhz@sustech.edu.cn.
⁷ State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China; Hefei National Laboratory, Hefei 230088, China. Electronic address: jinsongzhang@tsinghua.edu.cn.
⁸ State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China; New Cornerstone Science Laboratory, Frontier Science Center for Quantum Information, Beijing 100084, China; Hefei National Laboratory, Hefei 230088, China. Electronic address: yayuwang@tsinghua.edu.cn.

PMID: 37268443
DOI: 10.1016/j.scib.2023.05.011

Abstract

The recently discovered antiferromagnetic (AFM) topological insulator (TI) MnBi₂Te₄ represents a versatile material platform for exploring exotic topological quantum phenomena in nanoscale devices. It has been proposed that even-septuple-layer (even-SL) MnBi₂Te₄ can host helical hinge currents with unique nonlocal behavior, but experimental confirmation is still lacking. In this work, we report transport studies of exfoliated MnBi₂Te₄ flakes with varied thicknesses down to the few-nanometer regime. We observe giant nonlocal transport signals in even-SL devices when the system is in the axion insulator state but vanishingly small nonlocal signal in the odd-SL devices at the same magnetic field range. In conjunction with theoretical calculations, we demonstrate that the nonlocal transport is via the helical edge currents mainly distributed at the hinges between the side and top/bottom surfaces. The helical edge currents in the axion insulator state may find unique applications in topological quantum devices.

Keywords: Axion insulator; Edge state; Nonlocal transport; Topological insulator.