# Metal surface induces strong acoustic plasmons in chemically doped graphene

## TL;DR

This study investigates how metallic surfaces affect acoustic plasmons in chemically doped graphene, revealing that Coulomb screening suppresses these modes but can be mitigated by increasing separation, restoring plasmonic properties.

## Contribution

The paper demonstrates that metallic surfaces suppress graphene's acoustic plasmons through Coulomb screening, but separation can restore and enhance these plasmonic modes, providing new insights into graphene-metal interactions.

## Key findings

- Metallic surfaces suppress acoustic plasmons in doped graphene.
- Increasing separation between graphene and metal restores plasmonic modes.
- Enhanced acoustic plasmons observed with separation, not present in freestanding graphene.

## Abstract

Recent theoretical considerations have demonstrated that freestanding graphene doped with alkali metals (AC x ) supports strong Dirac and weak acoustic plasmons. Here we show that when AC x is deposited on a metallic surface, the intense Coulomb screening completely washes out these collective modes. However, even small increase of separation between AC x and metallic surface causes recovery of AC x plasmonic properties and especially the enhancement of acoustic plasmons intensities not present in the freestanding case. We further provide the physical background of these intriguing phenomena. The studied systems consist of lithium- and cesium-doped graphene deposited on Ir(111) surface.