We investigate the coupled lateral-normal response to a lateral external drive in a nanoscale molecular system confined between two atomically smooth solid surfaces. We discuss the effects of shear induced dilatancy, which results from the coupling, on the energy dissipation, and therefore on the frictional properties. It is demonstrated that measurements of response in the normal direction provide additional information on the mechanisms of friction and that manipulating the dilatancy opens new possibilities to control the motion in the lateral direction. The dilatancy leads to a novel memory effect which is amenable to experimental verification.

• Received 22 December 1998

DOI:https://doi.org/10.1103/PhysRevLett.82.4823