Direct Measurement of Electron-Phonon Coupling with Time-Resolved ARPES.

Umberto De Giovannini,Angel Rubio,Hannes Hübener,Shunsuke A. Sato

doi:10.1103/physrevlett.125.136401

Abstract

Time- and angular- resolved photoelectron spectroscopy is a powerful technique to measure electron dynamics in solids. Recent advances in this technique have facilitated band and energy resolved observations of the effect that excited phonons, have on the electronic structure. Here, we show with the help of abinitio simulations that the Fourier analysis of the time-resolved measurements of solids with excited phonon modes enables the determination of the band- and mode-resolved electron-phonon coupling directly from the experimental data without any additional input from theory. Such an observation is not restricted to regions of strong electron-phonon coupling and does not require strongly excited or hot phonons, but can be employed to monitor the dynamical renormalization of phonons in driven phases of matter.

Highlights

Electron-phonon coupling is one of the fundamental interactions in solids that determines a vast range of material phenomena, ranging from thermal properties like specific heat over carrier mobility in charge transport to the critical temperature of conventional superconductivity
In this Letter we show that FD-ARPES is an experimental technique that can directly observe the electronphonon coupling matrix elements [23] of single electronic bands with momentum space and mode resolution, elevating electron-phonon coupling to an observable of photoelectron spectroscopy
In the resulting FD-ARPES spectrum, shown in Fig. 1(b), one can already qualitatively observe from the intensity which bands are strongly coupled to the phonon mode across the Brillouin zone (BZ) and, for instance, by analyzing the phonon-pump fluence dependence of these signals one can obtain a qualitative measure of electronphonon coupling

Summary

Introduction

Electron-phonon coupling is one of the fundamental interactions in solids that determines a vast range of material phenomena, ranging from thermal properties like specific heat over carrier mobility in charge transport to the critical temperature of conventional superconductivity. In this Letter we show that FD-ARPES is an experimental technique that can directly observe the electronphonon coupling matrix elements [23] of single electronic bands with momentum space and mode resolution, elevating electron-phonon coupling to an observable of photoelectron spectroscopy.

Results

Conclusion