Electric field and charge doping induced superconducting transition in 2D freestanding perovskite barium bismuthate

We present an ab-initio study of monolayer BaBiO3 focused on how to harness the insulator-metal transition through suppression of the charge density wave (CDW) phase in this material. After the determination of the most stable structure for the free-standing monolayer, we investigate the effects of an applied electric field and of charge doping on the electronic properties of the system. Our results show that external electric fields of the order of 0.1-0.3 V/Å are able to stabilize the metallic phase, destroy the CDW phase and, in addition, lead to a metallic metastable phase. On this same footing, we show that hole doping could also suppress the CDW phase and drive the system toward a metallic phase with large electron-phonon coupling. To this end, we also study the dependence of the electron-phonon coupling on hole-doping concentration and show that this could drive the onset of superconductivity. Indeed, low-dimensional BaBiO3 is an extremely flexible material with electronic properties that could be tuned using different and possibly combined external tools such as electric fields and charge doping, paving the way to achieve effective control on the transition from the CDW, to the metallic and then superconducting phase.