Polaron formation in Bi-deficient BaBiO3

Abstract

$\mathrm{Ba}\mathrm{Bi}{\mathrm{O}}_{3}$ is a charged ordered Peierls-like perovskite well known for its superconducting properties upon K or Pb doping. We present a study on the transport and electronic properties of $\mathrm{Ba}\mathrm{Bi}{\mathrm{O}}_{3}$ perovskite with strong Bi deficiency. We show that it is possible to synthesize $\mathrm{Ba}\mathrm{Bi}{\mathrm{O}}_{3}$ thin layers with Bi vacancies above 8--10% by depositing an yttrium-stabilized zirconia capping layer. By combining transport measurements with ab initio calculations we propose a scenario where the Bi vacancies give rise to the formation of polarons and suggest that the electrical transport is dominated by the migration of these polarons trapped at ${\mathrm{Bi}}^{3+}$ sites. Our paper shows that cation vacancies engineering, hardly explored to date, appears as a promising pathway to tune the electronic and functional properties of perovskites.