Study of the influence of surface acoustic waves on friction

We present the study of the influence of surface acoustic waves (SAWs) on point-contact friction in scanning force microscopy. First, the effect of friction reduction due to Rayleigh-type SAWs was demonstrated. In order to visualize the dependence of this effect on the wave amplitude, we mapped standing wave fields in two dimensions. In order to detect and to distinguish between the influence of in-plane and vertical surface oscillation components on the cantilever´s torsion and bending, we employed both lateral force microscopy (LFM) and multimode scanning acoustic force microscopy (SAFM). We found that the friction reduction effect is only due to the vertical oscillation component. Moreover, as this effect doesn´t appear for purely inplane polarized Love waves, we conclude that the mechanical diode effect is most probably responsible for the SAW-induced lubrication