Charge transfer is of particular importance in manipulating the interface physics in transition-metal oxide heterostructures. In this work, we have fabricated epitaxial bilayers composed of polar 3d LaMnO3 and nonpolar 5d SrIrO3. Systematic magnetic measurements reveal an unexpectedly large exchange bias effect in the bilayer, together with a dramatic enhancement of the coercivity of LaMnO3. Based on first-principle calculations and X-ray absorption spectroscopy measurements, such a strong interfacial magnetic coupling is found closely associated with the polar nature of LaMnO3 and the strong spin-orbit interaction in SrIrO3, which collectively drive an asymmetric interfacial charge transfer and lead to the emergence of an interfacial reentrant spin/superspin glass state. Our study provides a new insight into the charge transfer in transition-metal oxide heterostructures and offers a novel means to tune the interfacial exchange coupling for a variety of device applications.
Keywords: charge transfer; interfacial magnetic coupling; molecular orbital coupling; polarity discontinuity; spin−orbit coupling.