Comment on "Evidence for absence of metallic surface states in BiO2-terminated BaBiO3 thin films"

TL;DR

This paper questions the validity of claims that BaBiO3 thin films have no metallic surface states, arguing that the experimental evidence may be insufficient due to potential issues in film quality and termination control.

Contribution

It critically assesses previous experimental claims about surface states in BaBiO3 films, emphasizing the need for better film quality and characterization.

Findings

Questions the evidence for absence of metallic surface states

Highlights potential issues in film fabrication and characterization

Suggests that high-quality, well-controlled films are necessary for conclusive results

Abstract

In a recent work by Ji Seop Oh et al., BaBiO3(001) thin films were grown on SrTiO3 by Pulsed Laser Deposition. It was argued that the films are BiO2-terminated from the modelling of angle-resolved photoemission spectroscopy experiments. The authors claim, in opposition to previous theoretical predictions, that there are no metallic surface states on their films. In this short comment we question that the authors have enough evidence to make such a claim, as we consider that the large mismatch between SrTiO3 and BaBiO3 and the lack of control of their fabrication process with reflection high energy electron difraction could unlikely give high quality films with a single BiO2- termination, which is one of the requisites for the stabilization of these surface metallic states.