  Doping the distorted-perovskite Mott insulators LaTiO$_3$ and GdTiO$_3$ with
a single SrO layer along the [001] direction gives rise to a rich correlated
electronic structure. A realistic superlattice study by means of the charge
self-consistent combination of density functional theory with dynamical
mean-field theory reveals layer- and temperature-dependent multi-orbital
metal-insulator transitions. An orbital-selective metallic layer at the
interface dissolves via an orbital-polarized doped-Mott state into an
orbital-ordered insulating regime beyond the two conducting TiO$_2$ layers. We
find large differences in the scattering behavior within the latter. Breaking
the spin symmetry in $\delta$-doped GdTiO$_3$ results in blocks of
ferromagnetic itinerant and ferromagnetic Mott-insulating layers which are
coupled antiferromagnetically.
