Near-surface Brownian motor with synchronously fluctuating symmetric potential and applied force

A model is suggested which accounts for the unidirectional surface-parallel motion of a Brownian particle under the action of fluctuating surface-inclined unbiased external force. The surface-normal force component induces amplitude fluctuations of the symmetric periodic near-surface potential, whereas the surface-parallel component makes the particle move along the surface. The combined effect of synchronous fluctuations of the symmetric potential and the applied force leads to the longitudinal drift of the particle. It is shown that the temperature dependence of the motor velocity is nonmonotonic, with the maximum governed by the range of the near-surface potential.