MnBi₂Te₄ family / (MnBi₂Te₄)(Bi₂Te₃)ₙ series (Manganese Bismuth Telluride homologous family)

A family of layered van der Waals magnetic topological materials built from magnetic MnBi₂Te₄ septuple layers (Te–Bi–Te–Mn–Te–Bi–Te) interleaved with a variable number n of non-magnetic Bi₂Te₃ quintuple layers, spanning MnBi₂Te₄ (n = 0), MnBi₄Te₇ (n = 1), and MnBi₆Te₁₀ (n = 2).

The parent compound MnBi₂Te₄ (space group R3̄m) is the first realized intrinsic antiferromagnetic topological insulator, combining A-type antiferromagnetic order (T_N ≈ 25 K) with topological surface states, which enables the quantum anomalous Hall effect, axion-insulator states, and layer-dependent magnetic topology.

Inserting Bi₂Te₃ spacer layers progressively increases the interlayer separation and thereby weakens the interlayer antiferromagnetic coupling: MnBi₄Te₇ (space group P3̄m1) has a lower ordering temperature and lies closer to a ferromagnetic ground state, while MnBi₆Te₁₀ (space group R3̄m) is even more strongly decoupled, exhibiting weak antiferromagnetic or near-ferromagnetic order.

This systematic magnetic dilution provides a tunable route to engineer axion insulators and quantum anomalous Hall physics, making the MnBi₂Te₄ family a central platform for studying the interplay between magnetism and band topology.

Related Sb-substituted variants such as Mn(Bi₀.₇₃Sb₀.₂₇)₄Te₇ further tune the carrier type and Fermi level toward charge neutrality while modulating the interlayer magnetic coupling, offering additional control for optimizing these topological states.