  Ab initio calculations are used to predict that a superlattice composed of
layers of LaTiO3 and LaNiO3 alternating along the [001] direction is a S=1 Mott
insulator with large magnetic moments on the Ni sites, negligible moments on
the Ti sites and a charge transfer gap set by the energy difference between Ni
d and Ti d states, distinct from conventional Mott insulators. Correlation
effects are enhanced on the Ni sites via filling the oxygen p states and
reducing the Ni-O-Ni bond angle. Small hole (electron) doping of the
superlattice leads to a two-dimensional single-band situation with holes
(electrons) residing on Ni dx2-y2 (Ti dxy) orbital and coupled to
antiferromagnetically correlated spins in the NiO2 layer.
