Commensurability-Dependent Phononic Superlubricity Between Molybdenum Disulfide Layers

This paper decodes the dependence of phononic superlubricity on commensurability caused by relative rotation between molybdenum disulfide (MoS2) layers. Results show that under commensurate state, due to the strong interfacial potential, the sliding probe exhibits obvious stick–slip phenomenon; the vibration frequencies of the probe and the substrate are coupled, constructing effective energy transfer channels. As the rotation angle increases, the stick–slip phase and probe inherent oscillation are coupled owing to the decreasing interfacial potential. Once the contacting state reaches to completely incommensurability, the probe only undergoes inherent oscillation. More importantly, we further find that the potential period is determined by the lattice period, which causes the frequency distribution of the excited phonons to remain unchanged although changes in rotation angle. In addition, the contribution of atoms adjacent to friction interface to frictional energy dissipation becomes more significant with the rotation angle increasing. These findings reveal the phononic mechanism of angle-dependent superlubricity between MoS2 layers and provide a viable approach for friction regulation.