Nonequilibrium phases for driven particle systems with effective orientational degrees of freedom

We show that a rich variety of nonequilibrium phases can be realized for interacting particles moving over a periodic substrate when the particles have effective internal orientational degrees of freedom. We specifically study driven colloidal molecular crystals where it has been established that n-merization produces effective orientational degrees of freedom. This system exhibits a polarization effect within the pinned phase, a remarkable variety of sliding phases, and has no single particle pinning regime. Similar dynamics should occur for other driven systems with effective orientational degrees of freedom such as sliding diatomic or higher-order states.