  Using a combination of density functional theory, tight-binding models, and
Hartree-Fock theory, we predict topological phases with and without
time-reversal symmetry breaking in oxide heterostructures. We consider both
heterostructures containing light transition metal ions, and those containing
heavy transition metal ions. We find the (111) growth direction naturally leads
to favorable conditions for topological phases in both perovskite structures
and pyrochlore structures. For the case of light transition metal elements,
Hartree-Fock theory predicts the spin-orbit coupling is effectively enhanced by
on-site multiple-orbital interactions and may drive the system through a
topological phase transition, while heavy elements with intrinsically large
spin-orbit coupling require much weaker, or even vanishing electron
interactions to bring about a topological phase.
