Confinement-Induced Chiral Edge Channel Interaction in Quantum Anomalous Hall Insulators

Ling Jie Zhou, Ruobing Mei, Yi Fan Zhao, Ruoxi Zhang, Deyi Zhuo, Zi Jie Yan, Wei Yuan, Morteza Kayyalha, Moses H.W. Chan, Chao Xing Liu, Cui Zu Chang

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Abstract

In quantum anomalous Hall (QAH) insulators, the interior is insulating but electrons can travel with zero resistance along one-dimensional (1D) conducting paths known as chiral edge channels (CECs). These CECs have been predicted to be confined to the 1D edges and exponentially decay in the two-dimensional (2D) bulk. In this Letter, we present the results of a systematic study of QAH devices fashioned in a Hall bar geometry of different widths under gate voltages. At the charge neutral point, the QAH effect persists in a Hall bar device with a width of only ∼72 nm, implying the intrinsic decaying length of CECs is less than ∼36 nm. In the electron-doped regime, we find that the Hall resistance deviates quickly from the quantized value when the sample width is less than 1 μm. Our theoretical calculations suggest that the wave function of CEC first decays exponentially and then shows a long tail due to disorder-induced bulk states. Therefore, the deviation from the quantized Hall resistance in narrow QAH samples originates from the interaction between two opposite CECs mediated by disorder-induced bulk states in QAH insulators, consistent with our experimental observations.

Original languageEnglish (US)
Article number086201
JournalPhysical review letters
Volume130
Issue number8
DOIs
StatePublished - Feb 24 2023

All Science Journal Classification (ASJC) codes

  • General Physics and Astronomy

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