Electron-phonon coupling in suspended graphene: supercollisions by ripples

TL;DR

This study demonstrates that supercollision processes involving flexural modes dominate electron-phonon interactions in suspended graphene at room temperature, with a temperature-dependent power law change indicating two-phonon quantum effects.

Contribution

It provides experimental evidence for supercollision scattering by ripples as the main electron-phonon energy transfer mechanism in high-quality suspended graphene.

Findings

Electron-phonon coupling power law changes from cubic to quintic with temperature.

Quadratic dependence on chemical potential reflects two-phonon quantum processes.

Supercollision scattering by ripples dominates in high-quality suspended graphene.

Abstract

Using electrical transport experiments and shot noise thermometry, we find strong evidence that "supercollision" scattering processes by flexural modes are the dominant electron-phonon energy transfer mechanism in high-quality, suspended graphene around room temperature. The power law dependence of the electron-phonon coupling changes from cubic to quintic with temperature. The change of the temperature exponent by two is reflected in the quadratic dependence on chemical potential, which is an inherent feature of two-phonon quantum processes.