Paramagnetic Colloidal Chians in Rotating Fields: Chaotic Routes to Periodic Orbits

We present computer simulations and experiments on dilute suspensions of
superparamagnetic particles subject to rotating magnetic fields. We focus
on chains of particles with different length and their decay routes to stable structures.
At sufficiently high rates, the chains generally undergo chaotic motion at
short times and decay to one of a number of possible periodic orbits that are indefinitely stable at non-Brownian limit. We show that many-body interactions are essential in determinign the final periodic orbits, however, the essential physics of the problem is captured even by disregarding them.