Rotational dynamics of semiflexible paramagnetic particle chains.

Paramagnetic particles have the unique ability to reversibly form magnetic chains. We have taken advantage of this property by permanently linking the chains with three linking chemistries to create flexible chains whose behavior changes with the application of a magnetic field. We study the behavior of these chains in a rotating magnetic field and model them as elastic rods. Rigid chains rotate as a solid body while flexible chains deform under the influence of magnetic, viscous, and elastic stresses. We find that the shapes chains assume in rotating magnetic fields confirm the chain flexibility determined from previous micromechanics measurements.