Axion Insulator State with ferromagnetic ordering in CrI3/Bi2Se3/MnBi2Se4 Heterostructure

Understand

Realizing axion insulator state with a uniform magnetization considerably facilitates experimental explorations of the intriguing topological magnetoelectric effect, a hallmark of three-dimensional (3D) topological insulators (TIs).

• Through density functional theory calculations and four-band model studies, we find that magnetic ions Cr3+ in monolayer CrI3 and Mn2+ in septuple-layer MnBi2Se4 have opposite exchange couplings to the topological surface states of 3D TI Bi2Se3.
• As an exciting result of such opposite exchange couplings, axion insulator state is realized by a uniform magnetization in CrI3/Bi2Se3/MnBi2Se4 heterostructure.
• Our work opens up opportunities for exploring topological magnetoelectric effect realized by the uniform magnetization induced axion insulator state in heterostructures of 3D TIs and two-dimensional van der Waals ferromagnetic insulators.