Interfacial Mott state in iridate-nickelate superlattices*

In new SrIrO₃/LaNiO₃ superlattices up to a full electron transfer at the interface from Ir to Ni is experimentally observed, triggering a massive structural and electronic reconstruction. The large crystal eld 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) congurations on both Ir and Ni sites. First-principles calculations agree well with the experimental results, supporting the formation of an intricate Mott state in the superlattices.