Coherent Modulation of Quasiparticle Scattering Rates in a Photoexcited Charge-Density-Wave System

TL;DR

This study combines experimental and theoretical methods to reveal how ultrafast optical excitation modulates quasiparticle scattering rates in a charge-density-wave system, highlighting the role of collective excitations and electronic structure.

Contribution

It introduces a novel analysis of transient scattering rate modulation in a CDW system using time-resolved photoemission and nonequilibrium Green's functions.

Findings

Transient modulation of quasiparticle relaxation rates observed

Electron-electron scattering phase space critically modulated by CDW excitation

Electronic band structure influences self-energy dynamics

Abstract

We present a complementary experimental and theoretical investigation of relaxation dynamics in the charge-density-wave (CDW) system TbTe$_3$ after ultrafast optical excitation. Using time- and angle-resolved photoemission spectroscopy, we observe an unusual transient modulation of the relaxation rates of excited photocarriers. A detailed analysis of the electron self-energy based on a nonequilibrium Green's function formalism reveals that the phase space of electron-electron scattering is critically modulated by the photoinduced collective CDW excitation, providing an intuitive microscopic understanding of the observed dynamics and revealing the impact of the electronic band structure on the self-energy.