Experimental signatures of the transition from acoustic plasmon to electronic sound in graphene.

ABSTRACT: Fermi liquids respond differently to perturbations depending on whether their frequency is higher (collisionless regime) or lower (hydrodynamic regime) than the interparticle collision rate. This results in a different phase velocity between the collisionless zero sound and the hydrodynamic first sound. We performed terahertz photocurrent nanoscopy measurements on graphene devices, with a metallic gate close to the graphene layer, to probe the dispersion of propagating acoustic plasmons, the counterpart of sound modes in electronic Fermi liquids. We report the observation of a change in the plasmon phase velocity when the excitation frequency approaches the electron-electron collision rate that is compatible with the transition between the zero and the first sound mode.

SUBMITTER: Barcons Ruiz D 

PROVIDER: S-EPMC10541005 | biostudies-literature | 2023 Sep

REPOSITORIES: biostudies-literature