Diffraction and transmission antiresonances of lattice waves in sparse two-dimensional arrays of defect atoms

Abstract

The paper theoretically studies the influence of diffraction on the transmission of displacement waves in discrete lattices through crystal planes with sparse two-dimensional arrays of periodically embedded point (atomic) defects by analytical lattice dynamics calculations and molecular dynamics simulations. Transmission through the sparse two-dimensional arrays of atomic defects results in destructive interference of the waves propagating through two paths and the appearance of antiresonances (transmission nodes) in transmission spectrum. It is shown that the diffracted waves can substantially reduce or enhance the phonon transmission and can produce an additional narrow transmission antiresonance, depending on the properties of atomic defects and interatomic interactions. Specific features of the diffraction in discrete lattices as compared with those in a continua are discussed. The influence of positional disorder in defect atoms distribution on lattice waves diffraction and transmission antiresonances is considered. It is demonstrated by the lattice dynamics calculations and molecular dynamics simulations that the diffraction and transmission antiresonances of lattice waves are not suppressed by moderate disorder in the defect atoms distribution. The presented results can be used in the design of novel devices for high-frequency acoustic switching, filtering and interferometry.