Interfacial Study of SrIrO₃-SrNbO₃ Superlattices Grown by Hybrid Molecular Beam Epitaxy

In recent years, there has been a significant surge of interest in 4d and 5d transition metal oxides due to their strong spin-orbit interactions and the consequent exotic phases such as correlated topological electronic states and spin structures. The heterointerface of such oxides is an excellent platform to investigate the intricate interplay among different order parameters, charge transfer phenomena, and emergent interfacial effects. SrNbO₃ is highly promising as a donor material and could be expected to donate electrons to SrIrO₃ [1], filling the hole-like pockets in the SrIrO₃ Fermi surface. To probe the interfacial phenomena in such a system, we successfully synthesized (SrNbO₃)_m/(SrIrO₃)_n superlattices with different thicknesses by using a hybrid molecular beam epitaxy system. The growth and crystallinity of the superlattices were monitored utilizing in-situ reflected high-energy electron diffraction, followed by ex-situ high-resolution XRD. The structures were also examined using scanning transmission electron microscopy (STEM). Temperature-dependent electrical transport measurements were carried out to probe the electronic nature of the superlattices. To observe the chemical states of the constituent elements and probe the charge transfer, we used in-vacuo X-ray photoelectron spectroscopy (XPS) and X-ray Absorption Spectroscopy (XAS).