Low-energy surface phonons of decagonal and icosahedral quasicrystals by inelastic He-atom scattering
Physical Review B 68(5): 054205
Low-energy surface phonons (Rayleigh mode) on quasicrystals were investigated by inelastic He-atom scattering. The tenfold surface of decagonal Al71.8Ni14.8Co13.4 and the fivefold surface of icosahedral Al70.5Pd21Mn8.5 are found to possess well-defined Rayleigh modes with isotropic sound velocities of about 3840 m/s and 3470 m/s, respectively. The observed sound velocities are in good agreement with calculations based on the respective bulk data. The experimental phonon dispersions exhibit quasi-Brillouin-zone centers located at strong Bragg peaks.