Fig. 5: DFT surface electronic structure calculations of ideal and defective MnBi2Te4.
From: Native point defects and their implications for the Dirac point gap at MnBi2Te4(0001)
a Illustration of the TSS real space distribution at the MnBi2Te4(0001) surface. The ∣Ψz∣2 profile corresponds to the band structure shown in panel b. The color coding for the atoms sorts is the same as in Fig. 1a. Unlike in the case of the ideal structure (Fig. 1a), the Mn-Bi intermixing leads to the appearance of the MnBi magnetic moments in the Bi layers that are coupled antiparallel to those in the central Mn layer of the same SL. The MnBi magnetic moments thus turn out to be located in the regions with a high weight of the TSS, strongly counteracting the effect from the magnetization of the central Mn layer, where the TSS weight is low. This is expected to lead to a strong reduction of the DP gap. The latter is illustrated in panels (b–d), where the MnBi2Te4 surface electronic structure in the defectless case (b) is compared to those with Mn-Bi intermixing when MnBi defect locates in the second (c) and sixth (d) atomic (Bi) layers counting from the surface (see a). Note that only the topological surface state is shown, while the bulk-like bands are omitted. The energy axes scales in (b, c) and (d) are different.
