Localization of acoustic phonons in a layered lattice

The possibility of weak localization of acoustic phonons in a nonideal layered-crystal lattice is studied. Analytical expressions are obtained for the thermal conductivity and diffusion coefficient tensors at low temperatures. The role of specific processes of interference scattering of phonons by phonon density fluctuations near defects under conditions of weak interaction between the layers is analyzed. It is shown that because of such processes a substantial renormalization of the diffusion coefficient in the presence of strong diagonal disorder is possible at relatively low frequencies, where the dispersion laws for the acoustic phonons display quasi-two-dimensional properties. A nonstandard low-temperature dependence of the thermal conductivity of the layered systems BSCCO and BSYCO is discussed.

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