Spectral Fingerprints of Electron-Plasmon Coupling

TL;DR

This paper introduces the plasmonic polaron model, a computationally efficient method to predict electron-plasmon coupling effects in spectral functions of materials like Si, Ge, GaAs, and diamond, revealing new insights into their electronic structure.

Contribution

The paper presents the plasmonic polaron model based on cumulant expansion, enabling accurate prediction of electron-plasmon interactions without GW self-energy calculations.

Findings

Identification of plasmonic polaron band structures in Si, Ge, and GaAs.

Assignment of silicon plasmon satellite features to Van Hove singularities.

Prediction of ARPES signatures of electron-plasmon coupling in multiple materials.

Abstract

We investigate the spectroscopic fingerprints of electron-plasmon coupling in integrated (PES) and angle-resolved photoemission spectroscopy (ARPES). To account for electron-plasmon interactions at a reduced computational cost, we derived the plasmonic polaron model, an approach based on the cumulant expansion of many-body perturbation theory that circumvents the calculation of the GW self-energy. Through the plasmonic polaron model, we predict the complete spectral functions and the effects of electron-plasmon coupling for Si, Ge, GaAs, and diamond. Si, Ge, and GaAs exhibit well-defined plasmonic polaron band structures, i.e., broadened replica of the valence bands redshifted by the plasmon energy. Based on these results, (i) we assign the structures of the plasmon satellite of silicon (as revealed by PES experiments) to plasmonic Van Hove singularities occurring at the L, $\Omega$, and X high-symmetry points and (ii) we predict the ARPES signatures of electron-plasmon coupling for Si, Ge, GaAs, and diamond. Overall, the concept of plasmonic polaron bands emerges as a new paradigm for the interpretation of electronic processes in condensed matter, and the theoretical approach presented here provides a computationally affordable tool to explore its effect in a broad set of materials.