Plasmonic polaron in self-intercalated 1T-TiS2

TL;DR

This study demonstrates the existence and tunability of plasmonic polarons in self-intercalated 1T-TiS2, revealing how electron-plasmon interactions can be controlled by external parameters using spectroscopy and first-principles calculations.

Contribution

It provides the first direct spectroscopic evidence of plasmonic polarons in a layered material and shows how their properties can be tuned by charge density, temperature, and dielectric screening.

Findings

Identification of plasmonic polaron satellites in ARPES spectra.

Demonstration of tunability of plasmonic polaron energy scale.

Evidence of dielectric screening effects on plasmonic polaron formation.

Abstract

Electron-boson coupling is central to a comprehensive understanding of the diverse physical phenomena emerging from many-body interactions. Yet less attention has been paid to how plasmons, collective bosonic modes of electron density oscillation, interact with conduction electrons and how external parameters can tune this interaction. Here, we present a clear display of composite quasiparticles stemming from electron-plasmon coupling, known as the plasmonic polaron, in self-intercalated 1T-TiS2, by using angle-resolved photoemission spectroscopy (ARPES), high-resolution electron energy loss spectroscopy (HR-EELS) and first-principles calculations. The single particle spectral function exhibits a distinctive plasmon-loss satellite with the same characteristic energy scale determined by HR-EELS measurements. The bosonic energy scale of plasmonic polaron is tunable by controlling charge carrier density and temperature, distinguishing itself from conventional polarons arising from electron-phonon interactions. Furthermore, we find that the dielectric screening strongly affects the formation of the plasmonic polaron states. Our findings provide direct spectroscopic evidence of plasmonic polarons and establish self-intercalated layered materials as a promising platform for studying, controlling, and harnessing plasmonic interactions in quantum materials.