Abstract
Michael Schmiedeberg: „Colloidal particles on substrates with decagonal and tetradecagonal symmetry”
University of Pennsylvania, Philadelphia, USA
In recent years, there has been a lot of interest in growing
quasicrystalline films by depositing atoms on the surfaces of
quasicrystals. We aim to contribute to these investigations by
concentrating on the structural features of the substrate potential
leaving aside chemical details. We study a model system consisting of a
2D charge-stabilized colloidal suspension in quasicrystalline potentials
with decagonal or tetradecagonal symmetry that in experiments are
realized by five or seven interfering laser beams.
We discover a rich phase behavior. Especially, at medium substrate
strengths, when the colloidal ordering results from a competition of the
colloidal interaction and the substrate potential, interesting
intermediate phases occur. For example, in dilute systems, we observe a
quasicrystalline phase which exhibits bond orientations in 20 different
directions [1]. On the other hand, for larger densities, the system
locks into a highly ordered phase that is close to an Archimedean tiling
[2]. Furthermore, our study gives a new insight into the question why
many five-fold symmetric quasicrystals have been identified in nature
while not a single quasicrystal with seven-fold symmetry has been
observed so far.
References
- M. Schmiedeberg and H. Stark, Phys. Rev. Lett. 101, 218302 (2008).
- J. Mikhael, J. Roth, L. Helden and C. Bechinger, Nature 454, 501 (2008).