A model for vibrational properties of the atomic interface in A/B fcc metals

• Coherent phonon transmission by an atomic interface in face-centered cubic (fcc) lattices is analyzed.
• The dynamics of the systems Cu/Ni and Ni/Cu are determined.
• The response of the local dynamics to the changes in the environment of the interface zone is examined.
• The interaction between continuum and localized modes leads to localized vibration states.

The motivation of this theoretical work is to introduce a model calculation for the elastic waves scattering and coherent phonon transport at an atomic nanojunction between face-centered cubic (fcc) leads. The model system A/B consists of two perfect semi-infinite fcc leads A and B, oriented in the same direction and joined by an atomic interface. It is applied to the system Cu/Ni and its inverse Ni/Cu. A theoretical approach based on the matching method is used to study the dynamics of the system A/B.The interface observables are numerically calculated, in the harmonic approximation, to investigate how the interface properties can respond to changes in the elastic force constants of the sub-lattice from where the elastic waves are incident. We have calculated the phonon scattering and the total coherent transmission via the fcc interface as elements of a Landauer–Büttiker-type scattering matrix. The calculated properties are presented for all accessible frequencies in the propagating interval and for the elastic force constants of the leads A and B. The system dynamics, the scattering, and transmission spectra via the atomic interface are analyzed as a function of the incident frequency per propagating mode of the perfect fcc waveguides. Our results show that the atomic interface is an effective phonon splitter and suggest that its characteristics may be controlled by varying its nanometric parameters. In addition, the localized phonon modes associated with the interface domain interact with propagating modes of the perfect fcc systems, located on both sides, leading to interference effects.