Dispersion relation of square lattice waves in a two-dimensional binary complex plasma

Binary complex plasmas consist of microparticles two different species and can form two-dimensional square lattices under certain conditions. The dispersion relations the lattice waves are derived for longitudinal transverse in-plane modes, assuming that out-of-plane mode is suppressed by strong vertical confinement. results compared with spectra obtained in Langevin dynamics simulations. Furthermore, we investigate dependence relation on charge ratio mass particle species.