Science https://doi.org/dmwz (2020)
The quantum Hall effect was originally observed in two-dimensional electron systems subjected to a magnetic field. Crucially, the magnetic field leads to nontrivial band topology and breaks time-reversal symmetry. A ferromagnetically ordered topological insulator simultaneously satisfies these two requirements so that the effect can occur even without an external field; this is referred to as the quantum anomalous Hall effect. Yujun Deng and co-workers have now reported the observation of this anomalous effect in an intrinsic magnetic topological insulator MnBi2Te4.
A quantized anomalous Hall response has been observed previously in a doped topological insulator. Doping endows the material itself with magnetism, but there is a caveat — the dopants act as impurities that limit the quality of the material. MnBi2Te4 is a topological insulator with intrinsic magnetic order from the Mn2+ ions, allowing the study of the quantum anomalous Hall effect in pristine crystals. Deng and co-workers showed that a quantized Hall response can be achieved under more relaxed conditions.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Li, Y. Free from doping. Nat. Phys. 16, 240 (2020). https://doi.org/10.1038/s41567-020-0852-6
Published:
Issue Date:
DOI: https://doi.org/10.1038/s41567-020-0852-6