期刊
NANO LETTERS
卷 23, 期 11, 页码 5048-5054出版社
AMER CHEMICAL SOC
DOI: 10.1021/acs.nanolett.3c00956
关键词
MnBi2Te4; antisite defect; interlayer exchange; kinetic barrier; Dirac point-relatedbands
The theoretically predicted gapped surface state of antiferromagnetic topological insulator MnBi2Te4 has been experimentally observed to have a smaller or even gapless surface state, which is caused by the defects in MnBi2Te4. The study identifies antisite Mn-Bi and Bi(Mn) as dominant defects and reveals their evolution during the phase transition from MnTe/Bi2Te3 to MnBi2Te4. It is found that complete elimination of Mn(Bi) and Bi-Mn defects in MnBi2Te4 through simple annealing is almost impossible due to high migration barrier in kinetics. Moreover, increasing concentration of Mn-Bi and Bi-Mn defects in MnBi2Te4 monolayer leads to the elimination of gap in the Dirac point-related bands, explaining the experimentally unobserved large-gap surface state. The results provide insight into the theoretical understanding of the synthesized MnBi2Te4's quality and experimentally measured topological properties.
MnBi2Te4, an antiferromagnetictopologicalinsulator, was theoretically predicted to have a gapped surface stateon its (111) surface. However, a much smaller gapped or even gaplesssurface state has been observed experimentally, which is thought tobe caused by the defects in MnBi2Te4. Here,we have theoretically identified the antisite Mn-Bi andBi(Mn) as dominant defects and revealed their evolution duringthe phase transition from MnTe/Bi2Te3 to MnBi2Te4. We found that the complete elimination ofMn(Bi) and Bi-Mn defects in MnBi2Te4 by simple annealing is almost impossible due to the highmigration barrier in kinetics. Moreover, the gap of the Dirac point-relatedbands in a MnBi2Te4 monolayer would be eliminatedwith an increasing concentration of Mn-Bi and Bi-Mn defects, which could explain the experimentally unobserved large-gapsurface state in MnBi2Te4. Our results providean insight into the theoretical understanding of the quality and theexperimentally measured topological properties of the synthesizedMnBi(2)Te(4).
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