Exploration of intrinsic magnetic topological insulators in multiple-MnTe-intercalated topological insulator Bi2Te3.

The fabrication of MnBi₂Te₄ family of materials has been demonstrated that intercalating magnetic MnTe layer into topological insulator Bi₂Te₃ is an efficient way to explore magnetic topological insulator. A natural question is that if multiple MnTe layers can be intercalated into Bi₂Te₃, meanwhile if the topological properties are well preserved. Based on first-principles calculations, we first confirm that multiple MnTe layers can be inserted into Bi₂Te₃ by forming antiferromagnetic Mn_nBi₂Te_3+n (n = 1–5) crystals, where each system is energetically stable and can be readily exfoliated down to a monolayer. Specifically, the structural phase transition from ABC to ABAC stacking happens when n ≥ 2. Further electronic band structure calculations and topological identification reveal that the magnetic Mn_nBi₂Te_3+n undergoes a topologically nontrivial to trivial phase transition when n > 2, which is attributed to that multiple MnTe layers destroy the topological property of Bi₂Te₃. In addition to applying compressed strain, the topological states can be restored by intercalating Bi₂Te₃ layers by forming (MnTe)_n(Bi₂Te₃)_m heterostructures. Most strikingly, it is found that the topological properties of (MnTe)_n(Bi₂Te₃)_m are universally determined by the ratio of n/m, once n/m ≤ 2.8, the desired topological states are recovered. Our notable findings enrich the family of magnetic topological insulator, providing opportunities to explore more intriguing topological phenomena. [ABSTRACT FROM AUTHOR]