Abstract
The intrinsic antiferromagnetic topological insulator MnBi2Te4 provides an ideal platform for exploring exotic topological quantum phenomena. Recently, the Chern insulator and axion insulator phases have been realized in few-layer MnBi2Te4 devices at low magnetic field regime. However, the fate of MnBi2Te4 in high magnetic field has never been explored in experiment. In this work, we report transport studies of exfoliated MnBi2Te4 flakes in pulsed magnetic fields up to 61.5 T. In the high-field limit, the Chern insulator phase with Chern number C = −1 evolves into a robust zero Hall resistance plateau state. Nonlocal transport measurements and theoretical calculations demonstrate that the charge transport in the zero Hall plateau state is conducted by two counter-propagating edge states that arise from the combined effects of Landau levels and large Zeeman effect in strong magnetic fields. Our result demonstrates the intricate interplay among intrinsic magnetic order, external magnetic field, and nontrivial band topology in MnBi2Te4.
Highlights
The intrinsic antiferromagnetic topological insulator MnBi2Te4 provides an ideal platform for exploring exotic topological quantum phenomena
It was demonstrated that helical phases analogous to the quantum spin Hall (QSH) phase exist in charge-neutral graphene[20,21] and non-symmorphic KHgSb crystal[22] in strong magnetic fields, which are characterized by quantized longitudinal resistance (Rxx) and zero Hall resistance (Ryx) plateau in certain magnetic fields and gate voltage (Vg) ranges
The physical picture of emergent Chern band gaps induced by Landau levels and the Zeeman effect gives a comprehensive understanding of the zero Hall plateau state-observed here in thin flakes of MnBi2Te4 in strong magnetic fields
Summary
The intrinsic antiferromagnetic topological insulator MnBi2Te4 provides an ideal platform for exploring exotic topological quantum phenomena. It was demonstrated that helical phases analogous to the QSH phase exist in charge-neutral graphene[20,21] and non-symmorphic KHgSb crystal[22] in strong magnetic fields, which are characterized by quantized longitudinal resistance (Rxx) and zero Hall resistance (Ryx) plateau in certain magnetic fields and gate voltage (Vg) ranges Inspired by these discoveries, it is imperative to find out the fate of the Chern insulator phase in MnBi2Te4 in strong magnetic fields, as has been discussed theoretically for magnetic TIs23,24. Because magnetic field couples with both magnetic moment and electron spin, for certain spin configurations of band structure, the combination of Landau levels and a sufficiently strong Zeeman energy may lead to topological quantum phenomena such as TRS-broken QSH effect or the quantum pseudospin Hall effect[23,24] which have been proposed theoretically but never been realized in the experiment
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