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 obtain ed for the thermal conductivity and diffusion coefficient tensors at l ow temperatures. The role of specific processes of interference scatte ring of phonons by phonon density fluctuations near defects under cond itions of weak interaction between the layers is analyzed. It is shown that because of such processes a substantial renormalization of the d iffusion coefficient in the presence of strong diagonal disorder is po ssible at relatively low frequencies, where the dispersion laws for th e acoustic phonons display quasi-two-dimensional properties. A nonstan dard low-temperature dependence of the thermal conductivity of the lay ered systems BSCCO and BSYCO is discussed. (C) 1998 American Institute of Physics.