Exchange bias and quantum anomalous nomalous Hall effect in the MnBi<sub>2</sub>Te<sub>4</sub>/CrI<sub>3</sub> heterostructure.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 32181356.
- Also identified by DOI 10.1126/sciadv.aaz0948 and PMC identifier 7060064.
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Abstract
The layered antiferromagnetic MnBi<sub>2</sub>Te<sub>4</sub> films have been proposed to be an intrinsic quantum anomalous Hall (QAH) insulator with a large gap. It is crucial to open a magnetic gap of surface states. However, recent experiments have observed gapless surface states, indicating the absence of out-of-plane surface magnetism, and thus, the quantized Hall resistance can only be achieved at the magnetic field above 6 T. We propose to induce out-of-plane surface magnetism of MnBi<sub>2</sub>Te<sub>4</sub> films via the magnetic proximity with magnetic insulator CrI<sub>3</sub>. A strong exchange bias of ∼40 meV originates from the long Cr-<i>e<sub>g</sub></i> orbital tails that hybridize strongly with Te <i>p</i> orbitals. By stabilizing surface magnetism, the QAH effect can be realized in the MnBi<sub>2</sub>Te<sub>4</sub>/CrI<sub>3</sub> heterostructure. Moreover, the high-Chern number QAH state can be achieved by controlling external electric gates. Thus, the MnBi<sub>2</sub>Te<sub>4</sub>/CrI<sub>3</sub> heterostructure provides a promising platform to realize the electrically tunable zero-field QAH effect.