Interfacial charge-transfer Mott state in iridate–nickelate superlattices

Abstract

We investigate SrIrO3/LaNiO3 superlattices in which we observe a full electron transfer at the interface from Ir to Ni, triggering a massive structural and electronic reconstruction. Through experimental characterization and first-principles calculations, we determine that a large crystal field splitting from the distorted interfacial IrO6 octahedra surprisingly dominates over the spin–orbit coupling and together with the Hund’s coupling results in the high-spin (S = 1) configurations on both the Ir and Ni sites. This demonstrates the power of interfacial charge transfer in coupling lattice, charge, orbital, and spin degrees of freedom, opening fresh avenues of investigation of quantum states in oxide superlattices.