First Principles Prediction of Topological Phases in Thin Films of Pyrochlore Iridates

Using density functional theory and Hartree-Fock theory, we predict topological phases in thin pyrochlore iridate films grown along the [111] direction. Including the full orbital structure of the the relevant d-orbitals and the strong but finite-spin orbit coupling strength, we find a two-dimensional time-reversal invariant topological insulator with a gap of up to ~.15eV is possible in a bilayer geometry, and a zero magnetic field quantum anomalous Hall state is possible in a trilayer geometry with a gap of up to ~0.1eV. Our results show that while the bulk pyrochlore iridates experimentally explored so far may not be promising for insulating topological phases, the thin film geometries are.