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arXiv · 2208.02339

A hybrid Monte Carlo study of bond-stretching electron-phonon interactions and charge order in BaBiO$_3$

Benjamin Cohen-Stead·Kipton Barros·Richard Scalettar·Steven Johnston
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Abstract

The relationship between electron-phonon ($e$-ph) interactions and charge-density-wave (CDW) order in the bismuthate family of high-temperature superconductors remains unresolved. We address this question using nonperturbative hybrid Monte Carlo calculations for the parent compound BaBiO$_3$. Our model includes the Bi $6s$ and O $2p_\sigma$ orbitals and coupling to the Bi-O bond-stretching branch of optical phonons via modulations of the Bi-O hopping integral. We simulate three-dimensional clusters of up to 4000 orbitals, with input model parameters taken from {\it ab initio} electronic structure calculations and a phonon energy $\hbar\Omega_0 = 60$~meV. Our results demonstrate that the coupling to the bond-stretching modes is sufficient to reproduce the CDW transition in this system, despite a relatively small dimensionless coupling. We also find that the transition deviates from the weak-coupling Peierls' picture. This work demonstrates that off-diagonal $e$-ph interactions in orbital space are vital in establishing the bismuthate phase diagram.

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Benjamin Cohen-Stead, Kipton Barros, Richard Scalettar, Steven Johnston. 2022-08-03. A hybrid Monte Carlo study of bond-stretching electron-phonon interactions and charge order in BaBiO$_3$. https://doi.org/10.1038/s41524-023-00998-6

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