Raman study of lattice dynamics in quasicrystals

We present the first Raman investigation of icosahedral quasicrystals. Broad structured bands in the energy range up to ~ 500 $cm^{-1} have been observed in a series of AlFeCu, AlPdMn and AlPdRe systems. Original information on the vibrational density of states g(omega) was obtained for AlPdRe; for AlFeCu and AlPdMn estimated g(omega) shows a good agreement with the previous neutron results, but demonstrates finer structure. Strong increase in the parameter of electron-vibrational coupling for the low-energy vibrations and its correlation with changes in electronic conductivity has been observed in the series from AlFeCu to AlPdRe. This suggests the increase of the degree of localization for these vibrational excitations and involved electronic states.