Abstract
We study phonon transport in random 3D lattices when the mean free path l becomes comparable to the lattice spacing a. Through numerical simulation, it is shown that in contrast to the electronic case, here the Ioffe-Regel criterion is inaccurate in the prediction of phonon localization. By using the Thouless criterion to pinpoint the mobility edge , a broad frequency regime is found below where kl≤1 but the phonon transport is still diffusive. The diffusion constant in this regime is given quantitatively by a/3, where is an energy transport velocity derived from a continuity relation.
- Received 1 June 1993
DOI:https://doi.org/10.1103/PhysRevLett.72.234
©1994 American Physical Society