Effect of phonon-phonon interactions on localization

TL;DR

This paper investigates how phonon-phonon interactions influence heat transport in disordered chains, showing that even slight anharmonicity transitions the system from localized to diffusive energy conduction.

Contribution

It demonstrates that small anharmonic effects can significantly alter heat conduction behavior in disordered systems, shifting from localization to diffusion.

Findings

Without anharmonicity, heat current decays exponentially with system size.

Introduction of anharmonicity results in a 1/N dependence of heat current.

Anharmonicity induces a transition from localized to diffusive transport.

Abstract

We study the heat current J in a classical one-dimensional disordered chain with on-site pinning and with ends connected to stochastic thermal reservoirs at different temperatures. In the absence of anharmonicity all modes are localized and there is a gap in the spectrum. Consequently J decays exponentially with system size N. Using simulations we find that even a small amount of anharmonicity leads to a J~1/N dependence, implying diffusive transport of energy.