Ballistic Heat Transfer and Energy Waves in an Electron System

TL;DR

This paper predicts a novel ballistic energy transfer mode in graphene's electron-hole plasma, where heat propagates as a wave with significantly higher velocity than phonon-based mechanisms, enabling new energy transduction approaches.

Contribution

It introduces a new wave-like energy transfer mode in electronic systems, distinct from diffusive heat conduction, with potential for high-speed energy transport in graphene.

Findings

Energy propagates as a collective oscillation in graphene's electron-hole plasma.

Propagation velocity is approximately 1000 times faster than phonon-based heat transfer.

Coupling to charge dynamics allows for all-electric excitation and detection.

Abstract

Materials in which heat and entropy can be transmitted by directed ballistic pulses can trigger new approaches to energy transduction in solids. We predict that a ballistic energy transfer mode, with heat propagation governed by a wave equation rather than a diffusion equation, can be realized for a thermal electron-hole plasma in graphene. The new behavior originates from rapid exchange of energy and momentum in particle collisions leading to energy propagation as a collective weakly-damped oscillation. Due to the electronic nature of this mode, the estimated propagation velocity can be ~10^3 times larger than that for previously studied phonon mechanisms. The energy mode is uncharged at charge neutrality, but becomes coupled to charge dynamics upon doping. This coupling can be used for all-electric excitation and detection of energy transport.