Condensed Matter Physics Seminar: Dynamics of Colloidal Quasicrystals

Abstarct:

Most of the research on quasicrystals, since their discovery over three decades ago, has concentrated on the study of solid-state quasicrystals in the form of inter-metallic alloys. In my talk I will present molecular dynamics studies motivated by recent experiments with quasicrystals that are made of colloidal suspensions subjected to external quasiperiodic potentials. These systems allow us to track the dynamics of individual colloids, giving us the opportunity to study quasicrystals in ways that were impossible before. Like periodic crystals, quasicrystals possess low-energy phonon excitations arising from the fluctuations of particles around their equilibrium positions. Quasicrystals possess additional and unique low-energy excitations, called phasons, arising from local rearrangements of particles. My studies have shown that even though it is difficult to disentangle the effects of phonons and phasons in global reciprocal-space measurements, such as the dynamical structure factor, one can clearly observe the two types of excitations in real-space measurements, thereby elucidating the unique nature of phason modes in quasicrystals. 

Supervisor: Prof. Ron Lifshitz

Seminar Organizer: Prof. Yoram Dagan