Band Alignment Tuning from Charge Transfer in Epitaxial SrIrO$_3$/SrCoO$_3$ Superlattices

Jibril Ahammad; Brian B. Opatosky; Tanzila Tasnim; John W. Freeland; Gabriel Calderon Ortiz; Jinwoo Hwang; Gaurab Rimal; Boris Kiefer; Ryan B. Comes

arXiv · 2511.04513

Band Alignment Tuning from Charge Transfer in Epitaxial SrIrO$_3$/SrCoO$_3$ Superlattices

Jibril Ahammad·Brian B. Opatosky·Tanzila Tasnim·John W. Freeland·Gabriel Calderon Ortiz·Jinwoo Hwang·Gaurab Rimal·Boris Kiefer·Ryan B. Comes

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Abstract

Understanding charge transfer at oxide interfaces is crucial for designing materials with emergent electronic and magnetic properties, especially in systems where strong electron correlations and spin-orbit coupling coexist. SrIrO$_3$/SrCoO$_3$ (SIO/SCO) superlattices offer a unique platform to explore these effects due to their contrasting electronic structures and magnetic behaviors. Building on past theory based on continuity of O 2p band alignment, we employ density functional theory (DFT) to model electron transfer from Ir to Co across the SIO/SCO interface. To characterize these effects, we synthesized epitaxial SIO/SCO superlattices via molecular beam epitaxy. Structural and transport measurements confirmed high crystallinity, metallic behavior, and suppression of Kondo scattering that has been reported in uniform SIO films. Further characterization via X-ray absorption spectroscopy (XAS) revealed orbital anisotropy and valence changes consistent with interfacial charge transfer. Co K- and L$_{2,3}$-edge and Ir L$_2$-edge spectra verified electron donation from Ir to Co, stabilizing the perovskite SCO phase and tuning the electronic structure of SIO via hole-doping. O K-edge XAS showed band alignment shifts in the SIO layer consistent with DFT predictions. Our work here provides a pathway for engineering oxide heterostructures with tailored magnetic and electronic properties.

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Jibril Ahammad, Brian B. Opatosky, Tanzila Tasnim, John W. Freeland, Gabriel Calderon Ortiz, Jinwoo Hwang, Gaurab Rimal, Boris Kiefer, Ryan B. Comes. 2025-11-06. Band Alignment Tuning from Charge Transfer in Epitaxial SrIrO$_3$/SrCoO$_3$ Superlattices. https://arxiv.org/abs/2511.04513

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