Transport and relaxation of current-generated nonequilibrium phonons from nonlocal electronic measurements

TL;DR

This study investigates how current-generated phonons behave and relax in nanoscale systems, revealing non-thermal distributions and nonlinear relaxation processes that impact heat management in electronic devices.

Contribution

It provides new insights into nonequilibrium phonon dynamics and relaxation mechanisms in nanoscale conductors, highlighting nonlinear processes over traditional thermal models.

Findings

Resistance varies linearly with current for thin spacers at cryogenic temperatures.

An additional quadratic resistance component appears with thicker spacers.

Phonons relax via nonlinear dynamical processes rather than simple phonon scattering.

Abstract

We study phonons generated by current in a Pt nanowire, by measuring resistance of another nanowire separated from the first one by an insulating spacer. For thin spacers, the resistance varies almost linearly with current at cryogenic temperatures, while an additional quadratic contribution emerges for thicker spacers. These observations suggest a non-thermal distribution of current-generated phonons that relax via strongly nonlinear dynamical processes rather than few-phonon scattering. Our results provide insight into the nonequilibrium phonon dynamics at nanoscale, which may facilitate efficient heat management in electronic nanodevices.