Electronic structure and anomalous Hall effect in the ferromagnetic 3d−5d superlattice SrMnO3/SrIrO3

The electronic structure and the anomalous Hall effect (AHE) at the recently grown $3d\text{\ensuremath{-}}5d$ superlattice structure ${({\mathrm{SrMnO}}_{3})}_{1}/{({\mathrm{SrIrO}}_{3})}_{1}$ are investigated theoretically using model and density-functional calculations. The observed ferromagnetism for the SMO layer, which becomes electron doped because of the charge transfer across the interface, is explained to be due to the Anderson-Hasegawa double exchange, while the SIO side becomes ferromagnetic due to the proximity effect and the Nagaoka physics of a hole-doped system. The broken time-reversal symmetry and the strong spin-orbit coupling in SIO provide the two essential ingredients for the AHE, which we describe within a square lattice model of $d$-orbitals relevant for the present structure. The model correctly predicts the order of magnitude of the anomalous Hall conductivity (AHC), which is computed using the Kubo formula. The density-functional results for the AHC are in good agreement with the experiments.