Anomalous Landau quantization in intrinsic magnetic topological insulators

Su Kong Chong; Chao Lei; Seng Huat Lee; Jan Jaroszynski; Zhiqiang Mao; Allan H MacDonald; Kang L Wang

doi:10.1038/s41467-023-40383-x

Anomalous Landau quantization in intrinsic magnetic topological insulators

Nat Commun. 2023 Aug 9;14(1):4805. doi: 10.1038/s41467-023-40383-x.

Authors

Su Kong Chong^#¹, Chao Lei^#², Seng Huat Lee^{3

4}, Jan Jaroszynski⁵, Zhiqiang Mao^{3

4}, Allan H MacDonald², Kang L Wang⁶

Affiliations

¹ Department of Electrical and Computer Engineering, University of California, Los Angeles, CA, 90095, USA. sukongc@g.ucla.edu.
² Department of Physics, The University of Texas at Austin, Austin, TX, 78712, USA.
³ 2D Crystal Consortium, Materials Research Institute, The Pennsylvania State University, University Park, PA, 16802, USA.
⁴ Department of Physics, The Pennsylvania State University, University Park, PA, 16802, USA.
⁵ National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL, USA.
⁶ Department of Electrical and Computer Engineering, University of California, Los Angeles, CA, 90095, USA. wang@seas.ucla.edu.

^# Contributed equally.

Abstract

The intrinsic magnetic topological insulator, Mn(Bi_1-xSb_x)₂Te₄, has been identified as a Weyl semimetal with a single pair of Weyl nodes in its spin-aligned strong-field configuration. A direct consequence of the Weyl state is the layer dependent Chern number, [Formula: see text]. Previous reports in MnBi₂Te₄ thin films have shown higher [Formula: see text] states either by increasing the film thickness or controlling the chemical potential. A clear picture of the higher Chern states is still lacking as data interpretation is further complicated by the emergence of surface-band Landau levels under magnetic fields. Here, we report a tunable layer-dependent [Formula: see text] = 1 state with Sb substitution by performing a detailed analysis of the quantization states in Mn(Bi_1-xSb_x)₂Te₄ dual-gated devices-consistent with calculations of the bulk Weyl point separation in the doped thin films. The observed Hall quantization plateaus for our thicker Mn(Bi_1-xSb_x)₂Te₄ films under strong magnetic fields can be interpreted by a theory of surface and bulk spin-polarised Landau level spectra in thin film magnetic topological insulators.

Abstract

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