Fig. 1. Crystal structure of MnBi₈Te₁₃.

(A) Powder XRD and the refinement of MnBi₈Te₁₃. Inset: Low-angle (0 0 l) XRD peaks of the cleaved ab surface of MnBi₈Te₁₃. a.u., arbitrary units. (B) STEM images of MnBi₈Te₁₃ made on a focused-ion beam sample. The purple blocks label the [MnBi₂Te₄] SL, and the blue blocks mark the [Bi₂Te₃] QL. (C) Schematic drawing of the crystal and magnetic structure of MnBi_2nTe_3n+1 (n = 0, 1, 2, 3, and 4) with the stacking sequence listed. A, B, and C represent the bilayers of BiTe₆ octahedra whose bottom Te atoms, center Bi atoms, and top Te atoms are on the cell edges, respectively. Magenta arrow, magnetic structure in the order state; blue block, edge-sharing BiTe₆ octahedra; magenta block, edge-sharing MnTe₆ octahedra, which are connected to the blue block via edge sharing. Inset: T_c (the critical temperatures) versus d_Mn-Mn (the interlayer distance between the adjacent Mn-Mn layers) and n versus d_Mn-Mn in MnBi_2nTe_3n+1 (n = 1, 2, 3, and 4).