Orientation-Dependent Optical Magnetoelectric Effect in Patterned BaTiO₃/La_0.67Sr_0.33MnO₃ Heterostructures

The optical magnetoelectric effect has been widely investigated, but obtaining the large and tunable optical magnetoelectric effect at room temperature is still a big challenge. We here design ferroelectric/ferromagnetic heterostructures with various orientations, which are composed of titanate BaTiO3 and manganese oxide La0.67Sr0.33MnO3. This artificial bilayer structure presents room-temperature ferroelectric and ferromagnetic properties. After patterning a 4 μm grating structure on the bilayer thin film, the optical magnetoelectric effect for near-infrared light is investigated systematically through the Bragg diffraction method. The relative change of diffracted light intensity of the order n = 1 has a strong dependence on the magnetization and polarization of the thin films, whether the superlattice is irradiated in reflection or transmission geometries. For (100)- and (111)-oriented samples, both show the room-temperature optical magnetoelectric effect, while the (111)-oriented thin film has a stronger optical magnetoelectric effect. These results pave the way for designing next-generation optical magnetoelectric devices based on the ferroelectric/ferromagnetic structure.