Charge transfer and metal-insulator transition in (CrO₂)/(TaO₂)superlattices

Various interfacial emergent phenomena have been discovered in tunable nanoscale materials, especially in artificially designed epitaxial superlattices. In conjunction, the atomically fabricated superlattices have exhibited a plethora of exceptional properties compared to either bulk materials separately. Here, the (CrO₂)/(TaO₂)superlattices composed of two lattice-matched metallic metal oxides are constructed. With the help of first-principle density-functional theory calculations, a computational and theoretical study of (CrO₂)/(TaO₂)superlattices manifests the interfacial electronic properties in detail. The results suggest that emergent properties result from the charge transfer from the TaO₂to CrO₂layers. At two special ratios of1:1and1:2betweenmandn, the superlattices undergo metal-to-insulator transition. Additionally, the bands below the Fermi level become narrower with the increasing thickness of the CrO₂and TaO₂layers. The study reveals that the electronic reconstruction at the interface of two metallic materials can generate interesting physics, which points the direction for the manipulation of functionalities in artificial superlattices or heterostructures within a few atomic layers.