Controlling sliding velocity by mode locking at nanoscale solid surfaces with lubricants

Driven dynamics and kinetic frictional phenomena at nanoscale solid–solid surfaces with lubricants in the presence of both dc and ac driving forces are studied numerically. Using a lattice model which consists of two rigid substrates and a monolayer of lubricant molecules, we found mode locking phenomena, that is, the dc sliding velocity is locked to be fixed values concerning the ac driving frequency for a finite range of the dc driving force. We discuss the details of the mode locking and the kinetic frictional force in connection with the control of friction at nanoscale.