superlattices and heterostructures grown by molecular beam epitaxy (MBE)*

Interfacial charge transfer in complex oxide films induces emergent electronic and magnetic properties in interfaces making them promising avenues for the study of quantum materials. To study DFT predictions [1] of charge transfer in ABO₃/AB’O₃ interfaces, we grew a series of (SrCoO_3-x)_n /(SrIrO₃)_n superlattices, where Ir is expected to donate charge to Co, using molecular beam epitaxy (MBE) on two different substrates: La_0.3Sr_0.7Al_0.65Ta_0.35O₃ (LSAT), and SrTiO₃ (STO). Good crystallinity of the superlattice was observed during growth using in-situ reflection high-energy electron diffraction (RHEED), followed by ex-situ X-ray diffraction (XRD). The epitaxial nature was further confirmed using scanning transmission electron microscopy (STEM) along with energy dispersive X-ray (EDX) spectroscopy. From temperature dependent transport measurements, we observed a metallic nature in the superlattice, with an increase in resistivity with increasing strain and a decrease in resistivity with shorter superlattice unit cell period, n. The chemical state of the superlattices was studied first using in-vacuo X-ray photoelectron spectroscopy (XPS), and interfacial charge transfer was confirmed using X-ray absorption spectroscopy (XAS). Our study provides a scope to explore charge transfer induced emergent properties in metastable oxide perovskites in superlattice or double-perovskite structures.