Static and dynamic properties of magnetic nanowires in nematic fluids (invited)

Microscopy experiments are employed to characterize the elastic interactions of magnetic nickel nanowires suspended in a nematic liquid crystal. The nematic imposes a torque on an isolated wire that increases linearly with the angle between the wire and the nematic director in a manner quantitatively consistent with predictions based on an analogy between the nematic elasticity and electrostatics. An extension of this analogy also explains a measured orientation-dependent repulsive force between a wire and a wall. The angular relaxation of a wire in response to the elastic torque displays a nonexponential time dependence from which effective viscosities for the fluid are determined. The behavior of a wire in a twisted nematic cell further demonstrates how spatial variations in the director can convert the torque to a controlled translational force that levitates a wire to a specified height. (c) 2005 American Institute of Physics.