Novel low-energy collective excitation at metal surfaces

TL;DR

This paper predicts a new low-energy acoustic plasmon at metal surfaces arising from surface-state and bulk band interactions, which could influence surface phenomena and enable new physics.

Contribution

It introduces a novel collective excitation at metal surfaces involving surface-state and bulk band interactions, with potential implications for surface physics.

Findings

Existence of a low-energy acoustic plasmon at metal surfaces.

Linear dispersion relation at small wave vectors.

Potential impact on surface phenomena and new physics.

Abstract

A novel collective excitation is predicted to exist at metal surfaces where a two-dimensional surface-state band coexists with the underlying three-dimensional continuum. This is a low-energy acoustic plasmon with linear dispersion at small wave vectors. Since new modern spectroscopies are especially sensitive to surface dynamics near the Fermi level, the existence of surface-state induced acoustic plasmons is expected to play a key role in a large variety of new phenomena and to create situations with potentially new physics.