Native defects in antiferromagnetic topological insulator MnBi2Te4

Using scanning tunneling microscopy and spectroscopy, we visualized the native defects in antiferromagnetic topological insulator MnBi2Te4. Two native defects, MnBi and BiTe antisites, can be well resolved in the topographic images. MnBi tend to suppress the density of states at the conduction band edge. Spectroscopy imaging reveals a localized peaklike local density of state at ∼80 meV below the Fermi energy. A careful inspection of topographic and spectroscopic images, combined with density functional theory calculation, suggests this results from BiMn antisites at Mn sites. The random distribution of MnBi and BiMn antisites results in spatial fluctuation of local density of states near the Fermi level in MnBi2Te4.