Thermally induced suppression of friction at the atomic scale

Abstract

Atomic-scale friction, as accessed in tip-based experiments, is investigated theoretically in the full range of surface corrugations, temperatures, and velocities. Emphasis is given to the regime of thermal drift, when the regular stick-slip behavior is completely ruined by thermal effects. The possibility of nearly vanishing friction ("thermolubricity") is predicted even for strong (overcritical) surface corrugations, when traditional models would predict significant friction. The manifestation of this effect in recently published experimental data is demonstrated.

Fluctuations and jump dynamics in atomic friction experiments

“…A similar mechanisms of molecular rebinding has been predicted through simulations of the rupture of adhesion bonds in dynamic force spectroscopy by Dudko et al 17 In recent theoretical study, Krylov et al have pointed out that the thermally activated jumps between atomic positions can create a situation of ultralow friction, provided that the scan velocity is small enough. 18 The jump mechanism is clearly observed in our experiments. Figures 3͑c͒ and 3͑d͒ exhibits signatures of jumps between positions and intermediate states, respectively.…”

Influence of carrier density on the friction properties of siliconpnjunctions

“…This increase, if present, should decrease, not increase, friction, as shown in recent works. [33][34][35] For the current and voltages used here, however, the temperature increase should be negligible based on simple calculations of thermal transport. 36 Finally, we explored the effects of tip passivation, which we achieved by intentionally coating the tip with an insulat- ing molecular film of hexadecylthiol molecules.…”

Current trends in the physics of nanoscale friction

“…While this statement may easily be academic for macroscopic sliders, where the waiting time could exceed the age of the universe, the consequence for microscopic or nanoscopic sliders is that friction must vanish in the limit of zero sliding velocity, then growing linearly at nonzero velocity. This is the essence of the substantial suppression of friction due to thermal effects, referred to in recent times as thermolubricity [77]. L. Prandtl first recognized the role of temperature in reducing friction [78].…”

“…In general, the energy landscape of an AFM tip dragged along an atomically flat substrate exhibits valleys and barriers, and thermal excitations at sufficiently low speed always provide sufficient energy to overcome local barriers and enable slip [79]. Thus, it is commonly expected that the friction of a dry nanocontact should classically decrease with increasing temperature provided no other surface or material parameters are altered by the temperature changes [77,[80][81][82][83].…”