Plasmonic polarons induced by alkali-atom deposition in hafnium disulfide (1$T$-HfS$_2$)

TL;DR

This study combines advanced theoretical calculations and experimental ARPES measurements to investigate how alkali-atom doping induces plasmonic polarons in the semiconducting 1T-HfS2, revealing strong electron-plasmon coupling effects.

Contribution

It provides a detailed first-principles analysis of electron-plasmon interactions in doped 1T-HfS2, highlighting surface screening effects on plasmonic polaron formation.

Findings

ARPES detects satellite features near conduction band minima.

First-principles calculations attribute features to electron-plasmon coupling.

Surface screening enhances electron-plasmon interactions.

Abstract

We combine ab-initio calculations based on many-body perturbation theory and the cumulant expansion with angle-resolved photoemission spectroscopy (ARPES) to quantify the electron-plasmon interaction in the highly-doped semiconducting transition metal dichalcogenide 1$T$-HfS$_2$. ARPES reveals the emergence of satellite spectral features in the vicinity of quasiparticle excitations at the bottom of the conduction band, suggesting coupling to bosonic excitations with a characteristic energy of 200 meV. Our first-principles calculations of the photoemission spectral function reveal that these features can be ascribed to electronic coupling to carrier plasmons (doping-induced collective charge-density fluctuations). We further show that reduced screening at the surface enhances the electron-plasmon interaction and is primarily responsible for the emergence of plasmonic polarons.