title: The origin of two-dimensional electron gases at oxide interfaces: insights from theory.
abstract: The response of oxide thin films to polar discontinuities at interfaces and surfaces has generated enormous activity due to the variety of interesting effects that it gives rise to. A case in point is the discovery of the electron gas at the interface between LaAlO3 and SrTiO3, which has since been shown to be quasi-two-dimensional, switchable, magnetic and/or superconducting. Despite these findings, the origin of the two-dimensional electron gas is highly debated and several possible mechanisms remain. Here we review the main proposed mechanisms and attempt to model expected effects in a quantitative way with the ambition of better constraining what effects can/cannot explain the observed phenomenology. We do it in the framework of a phenomenological model constructed to provide an understanding of the electronic and/or redox screening of the chemical charge in oxide heterostructures. We also discuss the effect of intermixing, both conserving and not conserving the total stoichiometry.
authors.affiliation: Theoretical Materials Physics, University of Liège, B-4000 Sart-Tilman, Belgium. Theory of Condensed Matter, Cavendish Laboratory, University of Cambridge, J J Thomson Avenue, Cambridge CB3 0HE, UK.
authors.forename: N C
authors.initials: NC
authors.lastname: Bristowe
authors.forename: Philippe
authors.initials: P
authors.lastname: Ghosez
authors.forename: P B
authors.initials: PB
authors.lastname: Littlewood
authors.forename: Emilio
authors.initials: E
authors.lastname: Artacho
mesh_terms: D004553:Electric Conductivity; D004583:Electrons; D005740:Gases / Q000737:chemistry*; D008956:Models, Chemical; D010087:Oxides / Q000737:chemistry*; D011789:Quantum Theory
chemical_list: D005740:Gases; D010087:Oxides