Designing iridate-based superlattice with large magnetoelectric coupling

摘要

The coupling between ferroelectric and magnetic order provides a powerful means to control magnetic properties with electric fields. In this study, we have investigated the magnetoelectric (ME) coupling in iridate-oxide based superlattices employing first-principles density functional theory (DFT) calculations. In particular, we have investigated several oxide superlattices, including (SrIrO3)(1)-(CaTiO3)(1) (SIO-CTO) and (SrIrO3)(1)-(BaTiO3)(1) (SIO-BTO), with an alternating single layer of SIO and CTO/BTO. We identify a very large ME coupling in SIO-BTO mediated by both lattice and electronic contributions. In comparison, moderate ME coupling constants are found in SIO-CTO. Further electronic and structural analyses reveal that the large ME coupling of SIO-BTO is caused by the large spin-orbit coupling of 5d iridium as well as the significant polarization induced in the SIO-BTO. Interestingly, we find that the ME coupling in SIO-BTO can further be enhanced by modulating epitaxial strain. These results suggest a route to significantly enhance the ME coupling effects, which might be applicable for other materials and practical applications.