Universal features of the defect-induced damping of lattice vibrations

TL;DR

This paper demonstrates that defects universally cause Ohmic damping of lattice vibrations with nonzero wavevector, explaining low-temperature phenomena like phason damping and linear specific heat in dielectrics.

Contribution

It reveals that defect-induced damping is a universal Ohmic effect affecting all nonzero wavevector lattice modes at zero temperature.

Findings

Defects cause universal Ohmic damping of lattice vibrations.

Explains large phason damping at low temperatures.

Accounts for linear-in-T specific heat in dielectrics.

Abstract

It is shown that any defect gives an Ohmic contribution to the damping of any normal mode of the crystal lattice with nonzero wavevector which does not vanish at zero temperature. This explains the large phason damping observed at low temperatures in incommensurate phases, and might be a key factor to understand the linear-in-$T$ specific heat observed in a number of real dielectrics at low enough temperatures.