Long lifetime of the E-1(u) in-plane infrared-active modes of h-BN

Article

关键词: HEXAGONAL BORON-NITRIDE;    HIGH-PRESSURE;    CRYSTALS;    ANHARMONICITY;    POLARITONS;   

DOI  :  10.1103/PhysRevB.101.235203

来源: SCIE

【 摘 要 】

We present an infrared reflectivity study of the E-1u in plane phonons of hexagonal BN as a function of temperature in the 40-680 K range. The infrared reflectance spectra of high-quality lamellar single crystals are accurately fitted using Lowndes' factorized form of the dielectric response, where the longitudinal-optic (LO) frequency is an independent adjustable parameter. From this analysis we obtain reliable values for the phonon damping of the IR-active E-1u phonons which couple to light and give rise to the phonon-polariton excitations in this hyperbolic material. Anharmonic coupling potentials are estimated from the temperature dependence of the damping parameters. The E-1u(LO) mode exhibits a substantially longer lifetime than its transverse-optic counterpart, as it is basically unaffected by isotopic-disorder scattering owing to the low density of phonon states around the E-1u(LO) frequency.

【 授权许可】

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