PHASON-STRAIN FIELD AND VIBRATIONAL SPECIFIC-HEAT IN ICOSAHEDRAL ALLICU

For an icosahedral system, phason-strain fields can be classified into two classes, transforming respectively under the GAMMA4 and GAMMA5 ir reducible representations of the icosahedral group. Group theory predi cts that the GAMMA4 phason-strain field, as the one observed in as-cas t quasicrystalline AlLiCu samples, is not coupled to phonon modes. The low temperature specific heat of AlLiCu samples was measured after 10 days of annealing which allows phason-strain elimination and leads to almost perfect samples. No vibrational contribution evolution is obse rved. Some consequences and implications are discussed.