Pattern switching and polarizability for colloids in optical-trap arrays.
We show that colloidal molecular crystal states interacting with a periodic substrate, such as an optical-trap array, and a rotating external field can undergo a rapid pattern switching in which the orientation of the crystal changes. In some cases, a martensiticlike symmetry switching occurs. It is also possible to create a polarized state where the colloids in each substrate minimum develop a director field which smoothly rotates with the external drive, similar to liquid-crystal behavior. These results open the possibility for creating different types of devices using photonic band-gap materials, and should be generalizable to a variety of other condensed matter systems with multiple particle trapping.
Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
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Olson Reichhardt