Surface Phason-Polaritons in Charge Density Wave Films

TL;DR

This paper investigates surface phason-polaritons in charge density wave films, revealing unique surface modes caused by anisotropic responses, with potential applications in submillimeter frequency technologies.

Contribution

It introduces a new class of surface phason-polaritons in CDW films, highlighting their unique properties and confinement due to anisotropy.

Findings

Two surface phason-polariton branches identified

Surface states confined to finite wave number bands

Presence of guided wave modes extending to large wave numbers

Abstract

The coupled non-radiative excitations of the electromagnetic field and phasons in films with a quasi one-dimensional charge density wave (CDW) are evaluated for P--polarization and CDW conducting axis inside the film. The prominent features are two surface phason-polariton branches extending from the CDW pinning frequency to the frequency of the longitudinal optical phason. These surface phason-polariton states are confined to a finite band of longitudinal wave numbers. Besides surface polaritons, infinite series of guided wave modes are found which extend to large wave numbers. These differences to usual phonon-polaritons are caused by the extreme anisotropy of the electric CDW reponse. This new class of surface polaritons is expected to be found in the submillimeter frequency range.