Polarons in highly doped atomically thin graphitic materials

TL;DR

This study uses diagrammatic Monte Carlo to analyze how electron-phonon interactions affect spectral functions and transport gaps in highly doped, symmetry-broken atomically thin graphitic materials, revealing polaronic features and spectral modifications.

Contribution

It provides the first detailed computational analysis of polaron spectral functions in doped graphene-like systems with broken sub-lattice symmetry, including effects of phonon dispersion and long-range interactions.

Findings

Electron-phonon coupling causes band-flattening and lifetime changes.

Transport gap increases with electron-phonon coupling at the K point.

Spectral gap decreases slightly despite increased transport gap.

Abstract

Polaron spectral functions are computed for highly doped graphene-on-substrate and other atomically thin graphitic systems using the diagrammatic Monte Carlo technique. The specific aim is to investigate the effects of interaction on spectral functions when the symmetry between sub-lattices of a honeycomb lattice has been broken by the substrate or ionicity, inducing a band gap. Introduction of electron-phonon coupling leads to several polaronic features, such as band-flattening and changes in particle lifetimes. At the K point, differences between energies on each sub-lattice increase with electron-phonon coupling, indicating an augmented transport gap, while the spectral gap decreases slightly. Effects of phonon dispersion and long-range interactions are investigated, and found to lead to only quantitative changes in spectra.