Atomic (phason) hopping in perfect icosahedral quasicrystals Al70.3Pd21.4Mn8.3 by time-of-flight quasielastic neutron scattering

We report neutron-scattering results on atomic hopping in quasicrystals (QC) in the system Al-Pd-Mn. Two distinct atomic jump times have been observed and studied as a function of temperature. The unusual temperature behavior reported previously for 3.9 Angstrom jumps in Al-Cu-Fe (and interpreted as evidence for assisted hopping) is also found here, such that it seems to be universal. We provide a full discussion of all previous quasi-elastic-scattering results in QC, and show that their most reasonable interpretation is in terms of atomic hopping (phason dynamics). The relation of these data to theoretical predictions of fast diffusion and depinning transitions in the phason dynamics is examined.