Electron-phonon coupling of epigraphene at millikelvin temperatures

TL;DR

This study explores charge and heat transport in epigraphene at millikelvin temperatures, revealing a logarithmic electrical conductivity and a T^4 dependence of electron-phonon heat transport, with implications for ultra-sensitive bolometers.

Contribution

It provides the first measurement of electron-phonon heat transport in epigraphene at mK temperatures, demonstrating a T^4 dependence and predicting ultra-sensitive bolometer performance.

Findings

Electrical conductivity shows logarithmic dependence over two decades in temperature.

Electron-phonon heat transport follows a T^4 dependence in clean 2D conductors.

Predicted noise-equivalent power of epigraphene bolometers is ~10^-22 W/√Hz.

Abstract

We investigate the basic charge and heat transport properties of charge neutral epigraphene at sub-kelvin temperatures, demonstrating nearly logarithmic dependence of electrical conductivity over more than two decades in temperature. Using graphene's sheet conductance as in-situ thermometer, we present a measurement of electron-phonon heat transport at mK temperatures and show that it obeys the $T^4$ dependence characteristic for clean two-dimensional conductor. Based on our measurement we predict the noise-equivalent power of $\sim 10^{-22}~{\rm W}/\sqrt{{\rm Hz}}$ of epigraphene bolometer at the low end of achievable temperatures.