High resolution angle resolved photoemission studies on quasi-particle dynamics in graphite

TL;DR

This study uses high-resolution ARPES to analyze quasi-particle dynamics in graphite, revealing the relationship between spectral function width, electron-phonon coupling, and temperature dependence near the Fermi level.

Contribution

It provides a detailed experimental and theoretical analysis of electron-phonon interactions in graphite, especially near the H point, with new insights into the coupling strength and phonon energy scales.

Findings

Spectral function width is proportional to energy near the H point.

Electron-phonon coupling parameter is approximately 0.23.

Phonon modes in graphite have energies higher than 125K.

Abstract

We obtained the spectral function of the graphite H point using high resolution angle resolved photoelectron spectroscopy (ARPES). The extracted width of the spectral function (inverse of the photo-hole lifetime) near the H point is approximately proportional to the energy as expected from the linearly increasing density of states (DOS) near the Fermi energy. This is well accounted by our electron-phonon coupling theory considering the peculiar electronic DOS near the Fermi level. And we also investigated the temperature dependence of the peak widths both experimentally and theoretically. The upper bound for the electron-phonon coupling parameter is ~0.23, nearly the same value as previously reported at the K point. Our analysis of temperature dependent ARPES data at K shows that the energy of phonon mode of graphite has much higher energy scale than 125K which is dominant in electron-phonon coupling.