Controlling friction energy dissipation by ultrafast interlayer electron-phonon coupling in WS2/graphene heterostructures

摘要

Electrons and phonons are regarded as the microscopic carriers of friction energy dissipation and their coupling is a typical dissipation mode. However, due to the lack of ultrafast detection technic, the friction mechani sm about electron -phonon coupling remains unexplained. Here, using high resolution non -contact atomic force microscopy and femtosecond transient absorption spectroscopy, we find that interlayer electron-phonon coupling dissipation channel in WS 2/graphene heterostructures can be opened by defects. This is because defects provide a recoil -momentum which satisfies the requirement of momentum conservation between electrons in WS 2 and acoustic phonons in graphene and interlayer electron -phonon coupling occurs. Besides, the electron-phonon scattering time is accelerated from 2.4 ps to 1.1 ps. The enhanced electron-phonon coupling leads to significant energy dissipation. We further quantitatively model the friction with dissipation rate as to control the friction energy dissipation by ultrafast interlayer electron -phonon coupling. This work provides a new way to understand the mechanism of electron -phonon coupling in friction.