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

Abstract

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.