Electron doping in single crystalline BaBiO$_3$: BaBiO$_{3-x}$F$_{x}$

TL;DR

This study successfully synthesized fluorine-doped BaBiO$_3$ single crystals, confirming electron doping effects on structure and electronic properties, and explored the potential for topological insulating states under electron doping.

Contribution

It reports the first successful growth of fluorine-doped BaBiO$_3$ single crystals and analyzes how F-doping influences their structural and electronic characteristics.

Findings

F-doping confirmed by X-ray photoelectron spectra

Single-phase F-doped BBO crystallizes in monoclinic structure

20% F-doped BBO appears multiphase

Abstract

Topological insulators are a new class of insulators with conducting surface state. Most of the topological insulators are chalcogenides, where a tiny amount of chalcogen vacancy destroys the predicted bulk insulating state and results in a metallic or semimetallic bulk electrical transport. BaBiO$_3$ (BBO) is an interesting large bandgap (0.7 eV) insulator that upon hole doping becomes a superconductor and is theoretically predicted to show a topological insulating state under electron doping. We have explored electron doping through the chemical substitution of fluorine atoms at the oxygen site. The single crystals of BBO and fluorine doped BBO were synthesized via a one-step solid-state technique. The single crystals of pure BBO and 10 % F -doped BBO (BaBiO$_{2.7}$F$_{0.3}$) are chemically single-phase samples and crystallize in monoclinic I2/m crystal structure. The core level and valence band X-ray photoelectron spectra confirm electron doping in the 10% fluorine-doped BBO. 20 % F-doped BBO appears to be a multiphase sample, confirmed by back-scattered electron (BSE) imaging and X-ray diffraction. This article reports on the successful growth of pure and F-doped BBO using a one-step solid-state technique and discusses the effect of F-doping on structural and electronic properties.