Interaction-induced quantum anomalous Hall phase in (111) bilayer of LaCoO$_3$

Abstract

In the present paper, the Gutzwiller density functional theory (LDA+G) has been applied to study a bilayer system of LaCoO$_3$ grown along the $(111)$ direction on SrTiO$_3$. The LDA calculations show that there are two nearly flat bands located at the top and bottom of $e_{g}$ bands of Co atoms with the Fermi level crossing the lower one, which is almost half-filled. After including both the spin-orbit coupling and the Coulomb interaction in the LDA+G method, we find that the interplay between spin-orbit coupling and Coulomb interaction stabilizes a very robust ferromagnetic insulator phase with non-zero Chern number, which indicates the possibility to realize quantum anomalous Hall effect in this system.