In the search of new 2D electron systems at the surface of BaBiO3 thin films

V. L. VILDOSOLA; F. GULLER; ANA MARÍA LLOIS; CRISTIAN FERREYRA; D. RUBI

Workshop; MULTIFUNCTIONAL OXIDES: SYNERGY BETWEEN FUNDAMENTAL SCIENCE AND NOVEL TECHNOLOGIES; 2017

The presence of 2D electron systems (2DES) at surfaces or interfaces in oxide thinfilms remains a hot topic in condensed matter physics. In particular, BaBiO3 is a material with fascinating properties already in bulk, presenting a charge ordered insulating phase that is in proximity of a superconducting one upon doping.It has also been suggested as a topological material very recently. In a previuos work, we have theoretically proposed that its(001) surface should become metallic if a Bi-termination is achieved and the mechanism behind this effect is predicted to be independent of the presence of oxygen vacancies or polar discontinuities. Here we report on the preparation by pulsedlaser deposition and characterization of BaBiO3 thin films on silicon. We showthat the texture of the films can be tuned by controlling the growthconditions, being possible to stabilize strongly (100)-textured films. We findsignificant differences on the spectroscopic and transport properties between(100)-textured and non-textured films. We rationalize these experimentalresults by performing first principles calculations, which indicate theexistence of electron doping at the (100) surface. This stabilizes Bi ions in a3+ state, shortens Bi-O bonds and reduces the electronic band gap, increasingthe surface conductivity. Our results emphasize the importance of surfaceeffects on the electronic properties of perovskites, and provide strategies todesign novel oxide heterostructures with potential interface-related 2DES.