Surface acoustic waves with transverse electric field

Surface acoustic waves, in particular Rayleigh waves near the surface of a piezoelectric material, have attracted a lot of attention lately through their abilities to carry electrons, and to couple strongly with superconducting qubits. Here we report a theoretical study of a previously unexplored surface mode in a piezoelectric material with transverse electric field. In particular, we develop a theory of elastic waves coupled with a general electromagnetic field and find the eigenmodes of the coupled wave. We clarify properties of this surface wave mode, such as its polarization, dispersion, and speed of sound at different propagation directions. While this surface mode cannot be used to carry an electron, it could play an important role when surface acoustic phonons are used as quantum bus to convey information between quantum dots.