Asymmetric interfaces sandwiched between infinite-layer oxides and perovskite oxides

Abstract

Asymmetric heterointerfaces that bridge two nonisostructural oxides provide valuable opportunities for novel emergent phenomena that may be unavailable for symmetric interfaces. Here we present a theoretical investigation on three different asymmetric interfaces consisting of the infinite-layer nickelate $\mathrm{LaNi}{\mathrm{O}}_{2}$ and the perovskite manganite $\mathrm{LaMn}{\mathrm{O}}_{3}$ (type A, B and C). An alternative crystal geometry, pyramid, is introduced when the planar-type $\mathrm{LaNi}{\mathrm{O}}_{2}$ and the $\mathrm{LaMn}{\mathrm{O}}_{3}$ are jointed at the interface, resulting in strong charge and orbital reconstruction. For type A interface, the magnetic moment per Mn ion has increased by 10% due to the replacement of $\mathrm{Mn}{\mathrm{O}}_{6}$ by $\mathrm{Mn}{\mathrm{O}}_{5}$. For type B interface, in contrast, the magnetic moment grew by 26% for the interfacial Ni ions due to the strong charge transfer between center nickel and apical oxygen. For type C interface, only slightly enhanced $\mathrm{Mn}{\mathrm{O}}_{6}$ distortions are observed and thus the change of charge and orbital occupancy are negligible. Our results demonstrated that an interface-selective orbital occupancy, where the Mn ${e}_{\mathrm{g}}$ orbital preferential occupation alternated from the out-of-plane ${\mathrm{d}}_{3{z}^{2}\ensuremath{-}{r}^{2}}$ state at type A interface to nearly degenerate at type C interface and then to in-plane ${\mathrm{d}}_{{x}^{2}\ensuremath{-}{y}^{2}}$ state at type B interface. The values of relative change of Mn ${e}_{\mathrm{g}}$ orbital occupancy are 15%, 2%, and \ensuremath{-}21%, respectively. The values of relative change at type A and B interface are larger than that achieved by strain $(\ensuremath{\sim}5%)$ or symmetric interface design (10%). Therefore, interface reconstructions lead to unusual electronic properties, opening space for the advancement of oxide electronics.