Directed Motion of Particles on a Surface

Abstract

Novel directed motion of particle lattices on a periodic surface is studied by numerical simulations based on an extended Frenkel-Kontorova model. The directed motion is induced by introducing the spatiotemporal modulation of natural length between particles in the presence of a periodic potential. The dynamical states where the directed motion occurs are classified into two characteristic regimes, i.e., locking regime and unlocking one. The adiabaticity of motion of the particle lattice against the spatiotemporal modulation is essentially important to understand the dynamical behaviors of the present system. For the directed motion under adiabatic conditions, time-averaged velocity of the particle lattice is locked to a fundamental value. The velocity locking can occur when the amplitude of the spatiotemporal modulation is larger than a certain threshold value. Using a scaling analysis of the threshold of modulation amplitude, we can reveal the scaling nature of the directed motion in the velocity locking state.