Violation of Fourier's Law and Anomalous Heat Diffusion in Silicon

TL;DR

This paper demonstrates that Fourier's law breaks down in silicon nanowires, showing length-dependent thermal conductivity and anomalous heat diffusion, challenging classical heat conduction theories in low-dimensional nanostructures.

Contribution

It provides systematic molecular dynamics evidence that Fourier's law does not hold in silicon nanowires, revealing anomalous heat diffusion and length-dependent thermal conductivity.

Findings

Thermal conductivity diverges with nanowire length up to 1100 nm.

Anomalous heat diffusion observed in silicon nanowires.

Fourier's law is invalid in low-dimensional nanostructures.

Abstract

We study heat conduction and diffusion in silicon nanowires (SiNWs) systematically by using non-equilibrium molecular dynamics. It is found that the thermal conductivity of SiNWs diverges with the length, even when the length is up to 1,100 nm which is much longer than the phonon mean free path. Moreover, an anomalous heat diffusion is observed which is believed to be responsible for the length dependent thermal conductivity. Our results provide strong evidence that Fourier's law of heat conduction is not valid in low dimensional nanostructures.