Electronic Structure of the Bond Disproportionated Bismuthate Ag$_2$BiO$_3$
Abstract
We present a comprehensive study on the silver bismuthate AgBiO, synthesized under high-pressure high-temperature conditions, which has been the subject of recent theoretical work on topologically complex electronic states. We present X-ray photoelectron spectroscopy results showing two different bismuth states, and X-ray absorption spectroscopy results on the oxygen -edge showing holes in the oxygen bands. These results support a bond disproportionated state with holes on the oxygen atoms for AgBiO. We estimate a band gap of 1.25~eV for AgBiO from optical conductivity measurements, which matches the band gap in density functional calculations of the electronic band structure in the non-symmorphic space group , which supports two inequivalent Bi sites. In our band structure calculations the disproportionated AgBiO is expected to host Weyl nodal chains, one of which is located 0.5~eV below the Fermi level. Furthermore, we highlight similarities between AgBiO and the well-known disproportionated bismuthate BaBiO, including breathing phonon modes with similar energy. In both compounds hybridization of Bi- and O- atomic orbitals is important in shaping the band structure, but in contrast to the Ba- in BaBiO, the Ag- bands in AgBiO extend up to the Fermi level.
Keywords
Cite
@article{arxiv.2106.09075,
title = {Electronic Structure of the Bond Disproportionated Bismuthate Ag$_2$BiO$_3$},
author = {Mohamed Oudah and Minu Kim and Ksenia S. Rabinovich and Kateryna Foyevtsova and Graham McNally and Berkay Kilic and Kathrin Küster and Robert Green and Alexander V. Boris and George Sawatzky and Andreas P. Schnyder and D. A. Bonn and Bernhard Keimer and Hidenori Takagi},
journal= {arXiv preprint arXiv:2106.09075},
year = {2021}
}