Towards novel emergent properties at BaBiO3 interfaces

V. L. VILDOSOLA; DI NAPOLI, SOLANGE

Workshop; "Materials for Computing"; 2020

H2020-RISE MELON (https://www.melon.ferroix.net/networking)

BaBiO3 has been theoretically proposed as a candidate system to present a 2D electronic gas for a (001)Bi-terminated surface [1]; however, this system has not been synthesized so far. It was shown, instead, for (100)-textured BaBiO3 thin films, from both spectroscopic measurements and ab-initio calculations, the presence ofsurface electronic effects associated with the absence of apical oxygens in Bi octahedra [2]. This reduces theelectronic band-gap and enhances the surface electrical conductivity. In this work, BaBiO3/YSZ bilayers weredeposited by laser ablation. YSZ is structurally compatible with the perovskite structure and behaves as an?oxygen scavenger?, which in principle could lead into a strong deoxigenation of a BaBiO3 layer close to theinterface. YSZ was deposited in a wide range of oxygen pressures and the electronic and transport propertiesof the interfaces were studied. An optimal pressure of 0.1 mbar was determined at which the conductivity ofthe interface is maximized. From transmission electron microscopy experiments, the presence of a Bi-deficientBaBiO3 layer close to the interface was determined. First-principle calculations were performed to study the effectof Bi vacancies on the material. Our theoretical results indicate that the presence of Bi vacancies leads into theformation of polarons and bipolarons, depending on the number of vacancies. It is proposed that the experimentallyobserved increase in conductivity at the interface is associated with the diffusion of bipolarons in the Bi-deficientperovskite zone.