Hyperbolic phonon polaritons and wave vector direction dependent dielectric tensors in anisotropic crystals

Fuente: arXiv
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Hauptverfasser: Fang, Yue, Chen, Huanjun, Li, Zhibing, Wang, Weiliang
Format: Preprint
Veröffentlicht: 2024
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author Fang, Yue
Chen, Huanjun
Li, Zhibing
Wang, Weiliang
author_facet Fang, Yue
Chen, Huanjun
Li, Zhibing
Wang, Weiliang
contents Hyperbolic phonon polariton is important in precisely controlling photons at the nanoscale. It was common practice to calculate the dielectric function of the phonon polariton system with the Drude-Lorenz model. We considered the impact of LO-TO splitting while applying the Drude-Lorenz model. Then the dielectric functions become wave vector direction dependent besides electric polarization direction dependent. Our results show that considering LO-TO splitting can more accurately predict dielectric functions. Additionally, we discovered that, besides hexagonal BN, hexagonal AlN exhibits a wide hyperbolic frequency band range, while the other four materials display it scarcely. Furthermore, we found that the phonon frequency, lifetime, and the difference of infrared active transverse optical phonon frequencies with different wave vector directions are critical factors in determining the width of the hyperbolic frequency band range. We also found some dumbbell-shaped and butterfly-shaped isofrequency curves in h-AlN, h-GaP, and especially h-GaN. Our study provides a fresh perspective on understanding the dielectric properties of these materials and lays a theoretical foundation for further exploration and development of new hyperbolic phonon polariton materials.
format Preprint
id arxiv_https___arxiv_org_abs_2402_11956
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Hyperbolic phonon polaritons and wave vector direction dependent dielectric tensors in anisotropic crystals
Fang, Yue
Chen, Huanjun
Li, Zhibing
Wang, Weiliang
Materials Science
Computational Physics
Optics
Hyperbolic phonon polariton is important in precisely controlling photons at the nanoscale. It was common practice to calculate the dielectric function of the phonon polariton system with the Drude-Lorenz model. We considered the impact of LO-TO splitting while applying the Drude-Lorenz model. Then the dielectric functions become wave vector direction dependent besides electric polarization direction dependent. Our results show that considering LO-TO splitting can more accurately predict dielectric functions. Additionally, we discovered that, besides hexagonal BN, hexagonal AlN exhibits a wide hyperbolic frequency band range, while the other four materials display it scarcely. Furthermore, we found that the phonon frequency, lifetime, and the difference of infrared active transverse optical phonon frequencies with different wave vector directions are critical factors in determining the width of the hyperbolic frequency band range. We also found some dumbbell-shaped and butterfly-shaped isofrequency curves in h-AlN, h-GaP, and especially h-GaN. Our study provides a fresh perspective on understanding the dielectric properties of these materials and lays a theoretical foundation for further exploration and development of new hyperbolic phonon polariton materials.
title Hyperbolic phonon polaritons and wave vector direction dependent dielectric tensors in anisotropic crystals
topic Materials Science
Computational Physics
Optics
url https://arxiv.org/abs/2402.11956