The electron-phonon coupling constant for single-layer graphene on metal substrates determined from He atom scattering

Recent theory has demonstrated that the value of the electron-phonon coupling strength lambda can be extracted directly from the thermal attenuation (Debye-Waller factor) of helium atom scattering reflectivity. This theory is here extended to multivalley semimetal systems and applied to the case of graphene on different metal substrates and graphite. It is shown that lambda rapidly increases for decreasing graphene-substrate binding strength. Two different calculational models are considered which produce qualitatively similar results for the dependence of lambda on binding strength. These models predict, respectively, values of lambda(HAS) = 0.89 and 0.32 for a hypothetical flat free-standing single-layer graphene with cyclic boundary conditions. The method is suitable for analysis and characterization of not only the graphene overlayers considered here, but also other layered systems such as twisted graphene bilayers.

Automated summary

Recent theory demonstrates the value of the electron-phonon coupling strength lambda can be extracted directly from thermal attenuation of helium atom scattering reflectivity. This theory is extended to multivalley semimetal systems and applied to graphene on different metal substrates and graphite, showing that lambda rapidly increases with decreasing graphene-substrate binding strength.