Orbital and Spin Reconstruction by Interface Symmetry Engineering in Oxide Superlattices

Abstract

Phase transitions in transition metal oxides, particularly those involving charge, orbital, and spin order, give rise to emergent electronic and magnetic phenomena, making these materials critical to the advancement of spintronics and quantum technologies. SrRuO₃ (SRO) and LaNiO₃ (LNO) have distinct physical properties. SRO is characterized by its metallic conductivity, ferromagnetism, and strong spin polarization, while LNO exhibits pronounced electron correlations and sensitivity to structural distortion. However, advancements in fabrication techniques and interface engineering have made it easier to integrate these materials into combined systems. In this work, the [5 nm SRO/t nm LNO]₁₀ superlattices are explored, where the interfacial coupling mechanisms give rise to intriguing electronic phenomena such as charge transfer, orbital hybridization, and spin rearrangement. The thickness-dependent X-ray absorption spectroscopy (XAS) and X-ray magnetic circular dichroism (XMCD) reveal a Ru-to-Ni charge transfer. Additionally, X-ray linear dichroism (XLD) measurements demonstrate reduced structural disorder and enhanced Ru-4d/Ni-3d orbital hybridization, mediated by O-2p states. This study addresses key challenges in developing functional oxide superlattices using mechanisms such as charge transfer, orbital hybridization, and spin reconstruction which offer new pathways for their application in next-generation spintronic devices and quantum materials.