Probing Nonlocal Effects in Metals with Graphene Plasmons

TL;DR

This paper investigates how nonlocal effects in metals influence graphene plasmon properties and demonstrates that graphene surface plasmons can serve as a sensitive probe for these effects in metallic nanostructures.

Contribution

The study reveals the impact of nonlocality on metallic surface plasmon-polaritons and proposes using graphene plasmons as a tool to probe nonlocal effects in metals.

Findings

Nonlocal effects significantly alter the spectrum of graphene surface plasmons.

Graphene surface plasmons can be used to detect nonlocal effects in metallic nanostructures.

Nonlocal effects reduce losses in graphene plasmons compared to local predictions.

Abstract

In this paper we analyze the effects of nonlocality on the optical properties of a system consisting of a thin metallic film separated from a graphene sheet by a hexagonal boron nitride (hBN) layer. We show that nonlocal effects in the metal have a strong impact on the spectrum of the surface plasmon-polaritons on graphene. If the graphene sheet is shaped into a grating, we show that the extinction curves can be used to shed light on the importance of nonlocal effects in metals. Therefore, graphene surface plasmons emerge as a tool for probing nonlocal effects in metallic nanostructures, including thin metallic films. As a byproduct of our study, we show that nonlocal effects lead to smaller losses for the graphene plasmons than what is predicted by a local calculation. We show that these effects can be very well mimicked using a local theory with an effective spacer thickness larger than its actual value.