  In a sharp contrast to the response of silica particles we show that the
metal-dielectric Janus particles with boojum defects in a nematic liquid
crystal are self-propelled under the action of an electric field applied
perpendicular to the director. The particles can be transported along any
direction in the plane of the sample by selecting the appropriate orientation
of the Janus vector with respect to the director. The direction of motion of
the particles is controllable by varying the field amplitude and frequency. The
command demonstrated on the motility of the particles is promising for tunable
transport and microrobotic applications.
