Topological insulators from complex orbital order in transition-metal oxides heterostructures

Topological band insulators which are dynamically generated by electron-electron interactions have been theoretically proposed in two- and three-dimensional lattice models. We present evidence that the two-dimensional version can be stabilized in digital (111) heterostructures of transition-metal oxides as a result of purely local interactions. The topological phases are accompanied by spontaneous ordering of complex orbitals and we discuss their stability with respect to the Hund's rule coupling, Jahn-Teller interaction, and inversion-symmetry breaking terms. As main competitors we identify spin-nematic and magnetic phases.