原子レベル構造制御による遷移金属酸化物の機能開発

抄録

Metal-oxygen bonds are responsible for a broad spectrum of functional properties of transition-metal oxides, and engineering the bonds is a key for exploring their properties. Artificial oxide heterostructures with chemically abrupt interfaces have provided a platform for engineering bonding geometries that could lead to emergent phenomena not seen in bulk oxides. In this paper, we demonstrate that interfacially engineering oxygen displacement is a good route for exploring structural and functional properties of oxides. Our high-resolution annular bright-field scanning transmission electron microscopy observations revealed that interfacial oxygen displacement determines metal-oxygen bond angles in entire heterostructures and the magnitude of the displacements can be adjusted by controlling propagations of the oxygen octahedral rotations across the heterointerface. We also show that by heterostructuring an itinerant ferromagnet SrRuO₃ with Ca_0.5Sr_0.5TiO₃ (0–4 monolayers thick) grown on a GdScO₃ substrate, structural phase and magnetic anisotropy of SrRuO₃ can be controlled through the interfacial engineering of its oxygen displacement.