Topological Crystalline Insulator Phases in Magnetic van der Waals Crystal MnBi₄Te₇ and Mn₂Bi₂Te₅ Families

In the past several years, the discoveries of multiple magnetic topological phases in MnBi2Te4 and its analogues have highlighted the research in modern condensed matter physics. The topological crystalline insulator (TCI) phase protected by space group symmetry is a valuable platform to understand the profound relation of crystalline symmetry and band topology in materials. Via first-principles calculations, we predict that the MnBi2Te4 analogues, MnBi4Te7, MnSb4Te7, Mn2Bi2Te5, and Eu2Bi2Te5, are all mirror-symmetry-protected TCI candidates when magnetized along the in-plane x orientation. Gapless surface states are expected for the van der Waals terminations in this phase. Particularly, the magnetic easy axis of Eu2Bi2Te5 is along the in-plane direction in our calculations. These findings open opportunities for research and application of magnetic TCIs and magnetically controllable topological quantum phase transitions.