Phononic origin of strain-controlled friction force

Employing fast Fourier transform (FFT) of instantaneous friction and interfacial phonon spectrum, phononic origin of friction between graphene layers, in which one layer suffering different biaxial strain, is disclosed. FFT spectrum indicates washboard frequencies make major contribution to friction. Peak value in FFT spectrum decreases with increase of strain, leading to drop of friction. Density of states for interface atoms proves energy exchange between tip and substrate is conditional on coupling of interfacial vibration frequencies. There is unified phonon spectrum on relative sliding surfaces at zero strain, which can establish effective energy dissipation channels. Once a strain is applied, unified phonon modes are no longer formed, which destroys conditions for establishment of energy dissipation channels and thus hinders energy dissipation.