Membranes with rotating motors.

We study collections of rotatory motors confined to two-dimensional manifolds. These systems show a nontrivial collective behavior since the rotational motion leads to a repulsive hydrodynamic interaction between motors. While for high rotation speed motors might exhibit crystalline order, they form at low speed a disordered phase where diffusion is enhanced by velocity fluctuations. These effects should be experimentally observable for motors driven by external fields and for dipolar biological motors embedded into lipid membranes in a viscoelastic solvent.