Surface elastic waves in solid composites of two-dimensional periodicity

We have studied the elastic surface waves in a truncated two-dimensional solid composite. The periodic structure is constituted by a square array of parallel tungsten (W) cylinders embedded in silicon (Si). The surface plane that terminates the crystal cuts perpendicularly the plane of periodicity along the (10) direction. Thus the surface plane is parallel to the axes of a row of cylinders. We found that surface waves can propagate with wave vector laying along the one dimensional surface periodicity that results from the truncation. Both mixed and transverse polarizations were considered, but only surface waves of mixed polarization exist when the truncation leaves complete cells at the surface. We have also studied the guidance of elastic waves by a homogeneous layer of Si grown at the surface of the crystal. The wave confinement within this adlayer is possible due to the scattering effects suffered by the field of displacement inside the periodic structure at frequencies in the band gaps.