Even-Odd Layer-Dependent Exchange Bias Effect in MnBi2Te4 Chern Insulator Devices

Bo Chen, Xiaoda Liu, Yuhang Li, Han Tay, Takashi Taniguchi, Kenji Watanabe, Moses H.W. Chan, Jiaqiang Yan, Fengqi Song, Ran Cheng, Cui Zu Chang

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

Magnetic topological materials with coexisting magnetism and nontrivial band structures exhibit many novel quantum phenomena, including the quantum anomalous Hall effect, the axion insulator state, and the Weyl semimetal phase. As a stoichiometric layered antiferromagnetic topological insulator, thin films of MnBi2Te4 show fascinating even-odd layer-dependent physics. In this work, we fabricate a series of thin-flake MnBi2Te4 devices using stencil masks and observe the Chern insulator state at high magnetic fields. Upon magnetic field training, a large exchange bias effect is observed in odd but not in even septuple layer (SL) devices. Through theoretical calculations, we attribute the even-odd layer-dependent exchange bias effect to the contrasting surface and bulk magnetic properties of MnBi2Te4 devices. Our findings reveal the microscopic magnetic configuration of MnBi2Te4 thin flakes and highlight the challenges in replicating the zero magnetic field quantum anomalous Hall effect in odd SL MnBi2Te4 devices.

Original languageEnglish
JournalNano Letters
DOIs
StateAccepted/In press - 2024

Keywords

  • antiferromagnetism
  • Chern insulator
  • exchange bias effect
  • intrinsic magnetic topological insulator
  • stencil mask

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