Broadband Focusing of Acoustic Plasmons in Graphene with an Applied Current

TL;DR

This paper theoretically investigates how an applied current in graphene with metallic gates can generate broadband, non-reciprocal acoustic plasmons that are directionally focused, with potential for experimental realization.

Contribution

It introduces a method to achieve broadband focused non-reciprocal plasmons in graphene via applied current and metallic gating, expanding control over plasmonic properties.

Findings

Spectral broadband focused plasmons are achievable.

Resonance linewidth depends on the angular direction due to Landau damping.

Forward focused non-reciprocal plasmons are predicted with accessible parameters.

Abstract

Non-reciprocal plasmons in current-driven, isotropic, and homogenous graphene with proximal metallic gates is theoretically explored. Nearby metallic gates screen the Coulomb interactions, leading to linearly dispersive acoustic plasmons residing close to its particle-hole continuum counterpart. We show that the applied bias leads to spectral broadband focused plasmons whose resonance linewidth is dependent on the angular direction relative to the current flow due to Landau damping. We predict that forward focused non-reciprocal plasmons are possible with accessible experimental parameters and setup.