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

TL;DR

This study uses advanced computational methods to predict that a bilayer of LaCoO$_3$ grown along the (111) direction can exhibit a robust quantum anomalous Hall phase due to the interplay of spin-orbit coupling and Coulomb interactions.

Contribution

First application of LDA+G to predict quantum anomalous Hall effect in LaCoO$_3$ bilayer with detailed analysis of electronic structure and topological properties.

Findings

Identification of nearly flat bands at the Fermi level in LaCoO$_3$ bilayer.

Prediction of a ferromagnetic insulator phase with non-zero Chern number.

Potential realization of quantum anomalous Hall effect in this material system.

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.