Temperature-induced enhancement of nanoscale friction.

We introduce a novel mechanism of temperature dependence of friction at the nanoscale which is determined by a decrease of the slip length with temperature T. We find that the effect of temperature on the slip length may result in a rich temperature dependence of friction, including a peak and/or plateau in F as a function of T, and a sharp increase or decrease of F with T. This mechanism is of primary importance in the multiple-slip regimes of motion when the tip slips over a number of lattice spacings. The influence of normal load and driving velocity on the temperature dependence of friction is discussed. We predict that the presence of surface defects or adsorbate may strongly influence the temperature dependence of friction.