Quantum Anomalous Hall State in Ferromagnetic SrRuO3 (111) Bilayers

SrRuO3 heterostructures grown in the (111) direction are a rare example of thin film ferromagnets. By means of density functional theory plus dynamical mean field theory we show that the half-metallic ferromagnetic state with an ordered magnetic moment of 2 μB/Ru survives the ultimate dimensional confinement down to a bilayer, even at elevated temperatures of 500 K. In the minority channel, the spin-orbit coupling opens a gap at the linear band crossing corresponding to 34 filling of the t2g shell. We predict that the emergent phase is Haldane's quantum anomalous Hall state with Chern number C=1, without an external magnetic field or magnetic impurities.