Tunable topological states in layered magnetic materials of MnSb2Te4, MnBi2Se4, and MnSb2Se4

The recently discovered magnetic topological insulator of $\mathrm{Mn}{\mathrm{Bi}}_{2}{\mathrm{Te}}_{4}$, has been successfully used to explore emerging physical phenomena, such as the quantum anomalous Hall effect (QAHE) and axion insulator state. Based on first-principles calculations, we have systematically investigated the electronic, magnetic, and topological properties of layered $\mathrm{Mn}{\mathrm{Sb}}_{2}{\mathrm{Te}}_{4}, \mathrm{Mn}{\mathrm{Bi}}_{2}{\mathrm{Se}}_{4}$, and $\mathrm{Mn}{\mathrm{Sb}}_{2}{\mathrm{Se}}_{4}$, where those materials host similar crystal structure as the $\mathrm{Mn}{\mathrm{Bi}}_{2}{\mathrm{Te}}_{4}$. Our calculations first show that each bulk system with antiferromagnetic order can be converted into a three-dimensional topologically nontrivial insulator by applying appropriate pressure. Then, we find that ferromagnetic (FM) $\mathrm{Mn}{\mathrm{Sb}}_{2}{\mathrm{Te}}_{4}$ is a type II Weyl semimetal with a single pair of Weyl points near Fermi level. Specifically, FM $\mathrm{Mn}{\mathrm{Bi}}_{2}{\mathrm{Se}}_{4}$ and $\mathrm{Mn}{\mathrm{Sb}}_{2}{\mathrm{Se}}_{4}$ can be readily converted into Weyl semimetals under pressure. Furthermore, we notice that QAHE can also be achieved in layered FM $\mathrm{Mn}{\mathrm{Sb}}_{2}{\mathrm{Te}}_{4}$ and $\mathrm{Mn}{\mathrm{Bi}}_{2}{\mathrm{Se}}_{4}$. All those findings demonstrate that the $\mathrm{Mn}{\mathrm{Bi}}_{2}{\mathrm{Te}}_{4}$-like materials of $\mathrm{Mn}{\mathrm{Sb}}_{2}{\mathrm{Te}}_{4}, \mathrm{Mn}{\mathrm{Bi}}_{2}{\mathrm{Se}}_{4}$, and $\mathrm{Mn}{\mathrm{Sb}}_{2}{\mathrm{Se}}_{4}$ are promising candidates to explore intriguing topological quantum states.