Polarons formation in Bi-deficient BaBiO$_3$

TL;DR

This study investigates how bismuth vacancies in BaBiO$_3$ induce polaron formation, affecting its electronic transport, and demonstrates vacancy engineering as a novel method to modify perovskite properties.

Contribution

It reveals that Bi-deficiencies lead to polaron formation in BaBiO$_3$, highlighting cation vacancy engineering as a new approach to tune perovskite electronic properties.

Findings

Bi-vacancies above 8-10% can be synthesized in BaBiO$_3$ thin layers.

Bi-vacancies induce polaron formation and influence electrical transport.

Transport is dominated by polaron migration trapped at Bi$^{3+}$ sites.

Abstract

BaBiO$_3$ 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 BaBiO$_3$ perovskite with strong Bi-deficiency. We show that it is possible to synthesize BaBiO$_3$ 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 an 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 Bi$^{3+}$ sites. Our work shows that cation vacancies engineering -- hardly explored to date -- appears as a promising pathway to tune the electronic and functional properties of perovskites.