Orbital order and possible superconductivity in LaNiO3/LaMO3 superlattices

Phys Rev Lett. 2008 Jan 11;100(1):016404. doi: 10.1103/PhysRevLett.100.016404. Epub 2008 Jan 10.


A hypothetical layered oxide La2NiMO6 where NiO2 and MO2 planes alternate along the c axis of ABO3 perovskite lattice is considered theoretically. Here, M denotes a trivalent cation Al, Ga,... such that MO2 planes are insulating and suppress the c-axis charge transfer. We predict that correlated eg electrons in the NiO2 planes develop a planar x2-y2 orbital order driven by the reduced dimensionality and further supported by epitaxial strain from the substrate. Low-energy electronic states can be mapped to a single-band t - t' - J model, suggesting favorable conditions for high-Tc superconductivity.