Transition from acoustic plasmon to electronic sound in graphene
Abstract
Fermi liquids respond differently to perturbations depending on whether their frequency is larger (collisionless regime) or smaller (hydrodynamic regime) than the inter-particle collision rate. This results in a different phase velocity between the collisionless zero sound and hydrodynamic first sound. We performed terahertz photocurrent nanoscopy measurements on graphene devices, with a metallic gate in close proximity to the sample, 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. This first observation of the first sound mode in an electronic Fermi liquid is of fundamental interest and can enable novel terahertz emitter and detection implementations.
Keywords
Cite
@article{arxiv.2301.07399,
title = {Transition from acoustic plasmon to electronic sound in graphene},
author = {David Barcons Ruiz and Niels C. H. Hesp and Hanan Herzig Sheinfux and Carlos Ramos Marimón and Curdin Martin Maissen and Alessandro Principi and Reza Asgari and Takashi Taniguchi and Kenji Watanabe and Marco Polini and Rainer Hillenbrand and Iacopo Torre and Frank H. L. Koppens},
journal= {arXiv preprint arXiv:2301.07399},
year = {2023}
}