Atomic-Scale Control of Electronic Structure and Ferromagnetic Insulating State in Perovskite Oxide Superlattices by Long-Range Tuning of BO₆ Octahedra

Control of BO₆ octahedral rotations at the heterointerfaces of dissimilar ABO₃ perovskites has emerged as a powerful route for engineering novel physical properties. However, its impact length scale is constrained at 2–6 unit cells close to the interface and the octahedral rotations relax quickly into bulk tilt angles away from interface. Here, a long-range (up to 12 unit cells) suppression of MnO₆ octahedral rotations in La_0.9Ba_0.1MnO₃ through the formation of superlattices with SrTiO₃ can be achieved. The suppressed MnO₆ octahedral rotations strongly modify the magnetic and electronic properties of La_0.9Ba_0.1MnO₃ and hence create a new ferromagnetic insulating state with enhanced Curie temperature of 235 K. The emergent properties in La_0.9Ba_0.1MnO₃ arise from a preferential occupation of the out-of-plane Mn d_3z²_−r² orbital and a reduced Mn e_g bandwidth, induced by the suppressed octahedral rotations. The realization of long-range tuning of BO₆ octahedra via superlattices can be applicable to other strongly correlated perovskites for exploring new emergent quantum phenomena.