Electron-phonon coupling in single walled carbon nanotubes determined by shot noise

TL;DR

This study measures shot noise in single-walled carbon nanotubes to analyze electron-phonon interactions, revealing different heat flow regimes dominated by acoustic and optical phonons at various bias voltages.

Contribution

It provides a quantitative analysis of electron-phonon coupling in nanotubes using shot noise measurements, introducing a model for heat flow involving both acoustic and optical phonons.

Findings

Strong noise suppression with increasing voltage.

Heat flow described by different models at intermediate and high biases.

Quantitative estimates of electron-phonon coupling parameters.

Abstract

We have measured shot noise in metallic single-walled carbon nanotubes of length L=1 $\mu$m and have found strong suppression of noise with increasing voltage. We conclude that the coupling of electron and phonon baths at temperatures $T_e$ and $T_{ph}$ is described at intermediate bias (20 mV $<$ \vv $\lesssim $ 200 mV) by heat flow equation $P=\Sigma L (T_e^3-T_{ph}^3)$ where $\Sigma \sim 3 \cdot 10^{-9}$ W/mK$^3$ due to electron interaction with acoustic phonons, while at higher voltages optical phonon - electron interaction leads to $P =\kappa_{op} L [N (T_e)-N(T_{ph})]$ where $N(T)= 1/(\exp(\hbar\Omega/k_BT)-1)$ with optical phonons energy $\hbar \Omega$ and $\kappa_{op}=2 \cdot 10^{2}$ W/m.