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 mech anism 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 WS2/graphen e heterostructures can be opened by defects. This is because defects provide a recoil-momentum which satisfies the requirement of momentum conservation between electrons in WS2 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 Γ with dissipation rate τ−1 as Γ = 2.75 × 10−17 τ−1 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.