Application of an electric field to colloidal particles suspended in a liquid-crystal solvent.

We study the behavior of colloidal particles suspended in a thermotropic nematic solvent in the presence of an electric field. For normal boundary conditions of the nematic director at the particles' surface, we show experimentally that an electric field applied along the dipolar axis of an elastic dipole induces a transition to an elastic quadrupolar configuration. Turning the field off makes the system go back to the initial state. We also show that it is possible to directly evidence an elastic quadrupolar repulsion between droplets.