Energy loss of the electron system in individual single-walled carbon nanotubes

TL;DR

This study measures how energy is lost in the electron system of individual metallic single-walled carbon nanotubes at low temperatures, using Johnson noise thermometry to relate resistance to electron temperature and analyze cooling mechanisms.

Contribution

It introduces a method to directly determine thermal conductance in nanotubes by linking resistance measurements to electron temperature, considering various cooling processes.

Findings

Resistance reflects electron temperature at finite bias.

Thermal conductance depends on nanotube length and temperature.

Cooling involves phonon emission and electron outdiffusion.

Abstract

We characterize the energy loss of the non-equilibrium electron system in individual metallic single-walled carbon nanotubes at low temperature. Using Johnson noise thermometry, we demonstrate that, for a nanotube with ohmic contacts, the dc resistance at finite bias current directly reflects the average electron temperature. This enables a straightforward determination of the thermal conductance associated with cooling of the nanotube electron system. In analyzing the temperature- and length-dependence of the thermal conductance, we consider contributions from acoustic phonon emission, optical phonon emission, and hot electron outdiffusion.