Effect of Bi vacancies at the interface between BaBiO3 and YSZ: transport and electronic properties

F. ROMANO; C. QUINTEROS; D. RUBI; W. ACEVEDO; G. RODRIGUEZ RUIZ; L. STEREN; S. DI NAPOLI; P. NUKALA; V. VILDOSOLA

VIRTUAL

Congreso; RAFA 2020; 2020

AFA

BaBiO3has 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 BaBiO3thin films, from both spectroscopic measurements and ab-initio calculations,the presence of surface electronic effects associated with the absence of apical oxygens in Bi octahe-dra [2]. This reduces the electronic band-gap and enhances the surface electrical conductivity. In thiswork, BaBiO3/YSZ bilayers were deposited by laser ablation. YSZ is structurally compatible with theperovskite structure and behaves as an ?oxygen scavenger?, which in principle could lead into a strongdeoxigenation of a BaBiO3layer close to the interface. YSZ was deposited in a wide range of oxygenpressures and the electronic and transport properties of the interfaces were studied. An optimal pressureof 0.1 mbar was determined at which the conductivity of the interface is maximized. From transmis-sion electron microscopy experiments, the presence of a Bi-deficient BaBiO3layer close to the interfacewas determined. First-principle calculations were performed to study the effect of Bi vacancies on thematerial. Our theoretical results indicate that the presence of Bi vacancies leads into the formation ofpolarons 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 theBi-deficient perovskite zone.[1] V. Vildosola et al., Phys. Rev. Lett. 110 (2013) 206805.[2] C. Ferreyra et al., AIP Advances 6 (2016) 065310