Fig. 2. Atomic structure of the novel heterostructure.

a Large scale HAADF-STEM image of the heterostructure measured at room temperature. The electron beam was incident along the [210] direction. Scale bar, 50 nm (horizontal white solid line). b, c Close-up image of region b and c in a, respectively. The inset shows the atomically-resolved image along the [110] direction showing the stacking sequence. The structure of the topmost layer is MnBi₂Te₄ (b) and Mn₄Bi₂Te₇ (c), respectively. Scale bar, 2 nm (horizontal white solid line). d, e EDS mapping along the arrow in b (d) and c (e), respectively, showing the chemical composition of the heterostructure.