  We numerically investigate a colloidal particle driven through a colloidal
crystal as a function of temperature. When the charge of the driven particle is
larger or comparable to that of the colloids comprising the crystal, a local
melting can occur, characterized by defect generation in the lattice
surrounding the driven particle. The generation of the defects is accompanied
by an increase in the drag force on the driven particle, as well as large noise
fluctuations. We discuss the similarities of these results to the peak effect
phenomena observed for vortices in superconductors.
