Atomic and electronic structures of correlated SrRuO₃/SrTiO₃ superlattices

Atomic-scale precision epitaxy of perovskite oxide superlattices provides unique opportunities for controlling the correlated electronic structures, activating effective control knobs for intriguing functionalities including electromagnetic, thermoelectric, and electrocatalytic behaviors. In this study, we investigated the close interplay between the atomic and electronic structures of correlated superlattices synthesized by atomic-scale precision epitaxy. In particular, we employ superlattices composed of correlated magnetic SrRuO₃ (SRO) and quantum paraelectric SrTiO₃ (STO) layers. In those superlattices, RuO₆ octahedral distortion (tilt angle) is systematically controlled from 167° to 175° depending on the thickness of the STO layers, also affecting the TiO₆ octahedral distortion within the STO layer. Customized octahedral distortion within SRO/STO superlattices in turn modifies the electronic structures of both the Ti and Ru compounds, observed by X-ray absorption spectroscopy. Our results identify the close correlation between atomic lattice and electronic structures enabled by the facile controllability of atomic-scale epitaxy, which would be useful for designing future correlated oxide devices.