Phonon transmission via nanojunctions in BCC waveguides

Coherent and ballistic phonon transport via nanojunctions between bcc lattices is presented. The model system A/B/A consists of a finite number of bcc atomic layers of an element B sandwiched between two bcc semi-infinite crystals of another element A. The matching method theoretical approach is used to study the dynamical properties of the bcc sandwich system. A calculation is presented for the coherent reflection and transmission scattering probabilities of the system phonons, as elements of a Landauer type scattering matrix. The scattering and transmission spectra via the nanojunctions are analyzed as a function of the incident frequency per propagating mode of the perfect bcc waveguides and as a function of the thickness of the sandwiched film and of a parameter that describes the nanojunction zones. The possible experimental measurements of this ballistic transmission in comparison with theoretical results should be a useful probe for the determination of alloying force constants across the interface between two such elements. Our results show that the nanojunction is an effective phonon splitter and suggest that its characteristics may be controlled by varying its nanometric parameters. Knowledge of these characteristics enables the authors to study all the vibrational properties of such a system.