Topological insulating phases in oxide multilayers using perovskites and rutiles

Ab initio calculations combined with tight-binding modelling have been performed\footnote{Phys. Rev. B 88, 155119 (2013).} in 5d-electron-based perovskite multilayers in the large spin-orbit coupling limit. The topological properties of the systems (SrTiO$_3$)$_7$/(SrIrO$_3$)$_2$ and isoelectronic (KTaO$_3$)$_7$/(KPtO$_3$)$_2$ grown along the (111) direction have been analyzed as a function of on-site Coulomb repulsion $U$, parity asymmetry and uniaxial strain. The former is found to be a topological semimetal and the latter is a topological insulator describable as the high-U limit of the other one. This high-U phase can be driven to a trivial insulating phase by a perpendicular external electric field. In the talk, we will describe how to proceed in a similar way with rutile-based multilayered structures, where a 4d/5d electron dioxide with rutile structure, sandwiched by a band insulator like TiO$_2$ or SnO$_2$ can lead to topologically non-trivial properties if band filling and strain are tuned. We discuss also the possibility of obtaining similar topological states using isoelectronic fluorides. The electronic structure and properties of free-standing thin films will be also briefly discussed.