Chern insulator at a magnetic rocksalt interface

Considerable efforts have recently been devoted to the experimental realization of a two-dimensional Chern insulator, i.e., a system displaying a quantum anomalous Hall effect. However, existing approaches such as those based on magnetic doping of topological-insulator thin films have resulted in small band gaps, restricting the effect to low temperatures. We use first-principles calculations to demonstrate that an interface between thin films of the topologically trivial ferromagnetic insulators EuO and GdN can result in a band inversion and a nonzero Chern number. Both materials are stoichiometric and the interface is nonpolar and lattice-matched, which should allow this interface to be achievable experimentally. We show that the band structure can be tuned by layer thickness or epitaxial strain, and can result in Chern insulators with gaps of over 0.1 eV.