Demonstration of Dissipative Quasihelical Edge Transport in Quantum Anomalous Hall Insulators

Shu-Wei Wang, Di Xiao, Ziwei Dou, Moda Cao, Yi-Fan Zhao, Nitin Samarth, Cui-Zu Chang, Malcolm R. Connolly, and Charles G. Smith
Phys. Rev. Lett. 125, 126801 – Published 18 September 2020
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Abstract

Doping a topological insulator (TI) film with transition metal ions can break its time-reversal symmetry and lead to the realization of the quantum anomalous Hall (QAH) effect. Prior studies have shown that the longitudinal resistance of the QAH samples usually does not vanish when the Hall resistance shows a good quantization. This has been interpreted as a result of the presence of possible dissipative conducting channels in magnetic TI samples. By studying the temperature- and magnetic-field-dependence of the magnetoresistance of a magnetic TI sandwich heterostructure device, we demonstrate that the predominant dissipation mechanism in thick QAH insulators can switch between nonchiral edge states and residual bulk states in different magnetic-field regimes. The interactions between bulk states, chiral edge states, and nonchiral edge states are also investigated. Our Letter provides a way to distinguish between the dissipation arising from the residual bulk states and nonchiral edge states, which is crucial for achieving true dissipationless transport in QAH insulators and for providing deeper insights into QAH-related phenomena.

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  • Received 6 April 2020
  • Accepted 17 August 2020

DOI:https://doi.org/10.1103/PhysRevLett.125.126801

© 2020 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Shu-Wei Wang1,*, Di Xiao2, Ziwei Dou1, Moda Cao1, Yi-Fan Zhao2, Nitin Samarth2, Cui-Zu Chang2, Malcolm R. Connolly3, and Charles G. Smith1

  • 1Department of Physics, Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE, United Kingdom
  • 2Department of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
  • 3Department of Physics, Imperial College London, London SW7 2AZ, United Kingdom

  • *Corresponding author. sww38@cam.ac.uk

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Issue

Vol. 125, Iss. 12 — 18 September 2020

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