One-dimensional Superdiffusive Heat Propagation Induced by Optical Phonon-Phonon Interactions

TL;DR

This paper reveals a new type of superdiffusive heat propagation driven by optical phonon interactions in one-dimensional systems, challenging existing theories and expanding understanding of thermal transport.

Contribution

It uncovers a novel superdiffusive heat propagation mechanism caused by optical phonon-phonon interactions in nonacoustic, momentum-nonconserving systems, without side peaks.

Findings

Identifies a non-Gaussian superdiffusive heat propagation without side peaks.

Shows this mechanism violates the Fourier law in certain low-dimensional systems.

Highlights the role of optical phonon interactions in thermal transport.

Abstract

It is known that one-dimensional anomalous heat propagation is usually characterized by a L\'{e}vy walk superdiffusive spreading function with two side peaks located on the fronts due to the finite velocity of acoustic phonons, and in the case when the acoustic phonons vanish, e.g., due to the phonon-lattice interactions such that the system's momentum is not conserved, the side peaks will disappear and a normal Gaussian diffusive heat propagating behavior will be observed. Here we show that there exists another type of superdiffusive, non-Gaussian heat propagation but without side peaks in a typical nonacoustic, momentum-nonconserving system. It implies that thermal transport in this system disobeys the Fourier law, in clear contrast with the existing theoretical predictions. The underlying mechanism is related to a novel effect of optical phonon-phonon interactions. These findings may open a new avenue for further exploring thermal transport in low dimensions.