Local polariton states in impure ionic crystals
نویسندگان
چکیده
We consider the dynamics of an ionic crystal with a single impurity in the vicinity of the polariton resonance. We show that if the polariton spectrum of the host crystal allows for a gap between polariton branches, the defect gives rise to local states with frequencies within the gap. Despite the atomic size of the impurity we find that the in-gap local states are predominated by long-wavelength polaritons. The properties of these states are shown to be different from the properties of the well-known vibrational local states. The difference is due to the singular behavior of the density of states of polaritons near the low-frequency boundary of the polariton gap. Assuming cubic symmetry of the defect site we consider a complete set of the local states arising near the bottom of the polariton gap. @S0163-1829~98!05909-8#
منابع مشابه
X iv : c on d - m at / 9 70 80 28 v 1 4 A ug 1 99 7 Local polariton states in impure ionic crystals
We consider dynamics of an ionic crystal with a single impurity in the vicinity of the polariton resonance. We show that if the polariton spectrum of the host crystal allows for a gap between polariton branches, the defect gives rise to a novel kind of local states with frequencies within the gap. Despite the atomic size of the impurity we find that new local states are predominated by long wav...
متن کاملar X iv : c on d - m at / 9 70 80 28 v 2 6 J an 1 99 8 Local polariton states in impure ionic crystals
We consider the dynamics of an ionic crystal with a single impurity in the vicinity of the polariton resonance. We show that if the polariton spectrum of the host crystal allows for a gap between polariton branches, the defect gives rise to a novel kind of local states with frequencies within the gap. Despite the atomic size of the impurity we find that new local states are predominated by long...
متن کاملLocal Polariton States in Polar Crystals with Impurities
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. Electromagnetic component of the states along with the corresponding excitations of the material are localized in the vicini...
متن کاملConcept of local polaritons and optical properties of mixed polar crystals
The concept of local polaritons is used to describe the optical properties of mixed crystals in the frequency region of their restrahlen band. It is shown that this concept allows for a physically transparent explanation of the presence of weak features in the spectra of so-called one-mode crystals and for one-two mode behavior. The previous models were able to explain these features only with ...
متن کاملDefect-induced resonant tunneling of electromagnetic waves through a polariton gap
– We consider tunneling of electromagnetic waves through a polariton band gap of a 1-D chain of atoms. We analytically demonstrate that a defect embedded in the structure gives rise to the resonance transmission at the frequency of a local polariton state associated with the defect. The optical properties of materials with band gaps in their electromagnetic spectrum have recently attracted a gr...
متن کامل