Pecularities of acoustic phonon scattering from a planar crystal defect and pseudosurface phonons (Resonant scattering of transverse phonons from a thin defect layer)

Abstract

A scattering of acoustical phonons from a planar crystal defect is studied. A resonance reflection of the transverse phonons from the planar defect is discovered and conditions of such a reflection are investigated. It is shown that the resonance conditions are connected with existence of longitudinal phonons localized at the planar defect and travelling along it. The problem is analyzed basing both on the lattice dynamics and on the theory of elasticity. A non-symmetrical stationary solution which consists of (1) a homogeneous transverse wave propagating only in one elastic semispace and (2) longitudinal localized waves in the both elastic semispaces is found. The condition of the resonance reflection of the transverse phonons from the defect layer coincides with a condition under which the non-symmetrical stationary vibration exists. The influence of properties of the models considered on the resonance frequencies is discussed.