Direct measurement of the electron energy relaxation dynamics in metallic wires

TL;DR

This paper introduces a method to directly measure electron energy relaxation times in metallic wires by analyzing thermal noise response to ac excitation, providing insights into electron-phonon interactions and heat capacity at low temperatures.

Contribution

It presents a novel, reliable technique to measure inelastic relaxation times and heat capacity in metallic conductors using thermal noise impedance analysis.

Findings

Measured electron-phonon scattering times at low temperatures.

Determined electron diffusion times in metallic wires.

Provided heat capacity measurements for thin film samples.

Abstract

We present measurements of the dynamical response of thermal noise to an ac excitation in conductors at low temperature. From the frequency dependence of this response function - the noise thermal impedance - in the range 1 kHz-1 GHz we obtain direct determinations of the inelastic relaxation times relevant in metallic wires at low temperature: the electron-phonon scattering time and the diffusion time of electrons along the wires. Combining these results with that of resistivity provides a measurement of heat capacity of samples made of thin film. The simplicity and reliability of this technique makes it very promising for future applications in other systems.