Local Polariton States in Polar Crystals with Impurities

TL;DR

This paper demonstrates that impurities in polar crystals can create unique localized polariton states within the gap, combining crystal excitations and electromagnetic fields, localized near the impurity.

Contribution

It introduces the concept of local polariton states in ionic crystals caused by impurities, a novel phenomenon in solid-state physics.

Findings

Local polariton states exist within the polariton gap.

States are a hybrid of crystal excitations and electromagnetic fields.

States are localized near impurities.

Abstract

We show that an impurity embedded in an ionic crystal can give rise to a novel kind of local states. These states exist within a polariton gap of a material and are a mix of excitations of the crystal, such as phonons or excitons, and the transverse electromagnetic field. The electromagnetic component of the states along with the corresponding excitations of the material are localized in the vicinity of an impurity.