Phason-strain-field influences on low-temperature specific heat in icosahedral quasicrystals Al-Li-Cu and Al-Fe-Cu

We investigated the phason-strain-field influences on electronic and vibrational properties of two icosahedral quasicrystals, Al-Li-Cu and Al-Fe-Cu. For that purpose we performed low-temperature specific-heat measurements on samples before and after annealing treatments that allowed strong phason-strain elimination. The electronic specific heat for the two systems is found to be scarcely sensitive to the annealing treatments, while the vibrational specific heat displays a different behavior: it remains unchanged in Al-Li-Cu, but is strongly reduced in Al-Fe-Cu after annealing. We interpret this to arise from the correlation between the symmetry of the phason-strain field and the electronic and vibrational properties.