Coherent Phonons Scattering by Interstitial Impurities in QuasiPlanar crystals

Abstract

using the matching method formalism, this work presents the transmission and reflection coefficients of coherent phonons in a quasi 2D quantum waveguide perturbed by reticular defects as interstitial impurities. Our waveguide is modelled by two infinite atomic chains. The implied interactions refer only to the bonding strengths between nearest and next nearest close neighbours. .Numerical results show that the transmission spectra exhibit Fano-like resonance features which result from degeneracy of localized-impurity states and propagating continuum modes. In addition, the scattering by multiple impurities induces interferences between diffused and reflected waves in the defect region giving birth to Fabry-Pérot oscillations. This interference phenomenon could provide an interesting alternative to investigate structural properties of materials. The results could be also useful for the design of phonon devices.