%0 Journal Article
%T Isotopic effects on phonon anharmonicity in layered van der Waals crystals: Isotopically pure hexagonal boron nitride
%+ Institute of Earth Sciences Jaume Almera
%+ Department of Physics [Kansas]
%+ Laboratoire Charles Coulomb (L2C)
%A Cusco, Ramon
%A Artus, Luis
%A Edgar, James H.
%A Liu, Song
%A Cassabois, Guillaume
%A Gil, Bernard
%< avec comité de lecture
%Z L2C:18-079
%@ 2469-9950
%J Physical Review B
%I American Physical Society
%V 97
%N 15
%P 155435
%8 2018
%D 2018
%R 10.1103/PhysRevB.97.155435
%Z Physics [physics]/Condensed Matter [cond-mat]/Other [cond-mat.other]Journal articles
%X Hexagonal boron nitride (h-BN) is a layered crystal that is attracting a great deal of attention as a promising material for nanophotonic applications. The strong optical anisotropy of this crystal is key to exploit polaritonic modes for manipulating light-matter interactions in 2D materials. h-BN has also great potential for solid-state neutron detection and neutron imaging devices, given the exceptionally high thermal neutron capture cross section of the boron-10 isotope. A good knowledge of phonons in layered crystals is essential for harnessing long-lived phonon-polariton modes for nanophotonic applications and may prove valuable for developing solid-state 10BN neutron detectors with improved device architectures and higher detection efficiencies. Although phonons in graphene and isoelectronic materials with a similar hexagonal layer structure have been studied, the effect of isotopic substitution on the phonons of such lamellar compounds has not been addressed yet. Here we present a Raman scattering study of the in-plane high-energy Raman active mode on isotopically enriched single-crystal h-BN. Phonon frequency and lifetime are measured in the 80–600-K temperature range for 10B-enriched, 11B-enriched, and natural composition high quality crystals. Their temperature dependence is explained in the light of perturbation theory calculations of the phonon self-energy. The effects of crystal anisotropy, isotopic disorder, and anharmonic phonon-decay channels are investigated in detail. The isotopic-induced changes in the phonon density of states are shown to enhance three-phonon anharmonic decay channels in 10B-enriched crystals, opening the possibility of isotope tuning of the anharmonic phonon decay processes.
%G English
%2 https://hal.science/hal-01807107/document
%2 https://hal.science/hal-01807107/file/PhysRevD.95.pdf
%L hal-01807107
%U https://hal.science/hal-01807107
%~ CNRS
%~ L2C
%~ MIPS
%~ UNIV-MONTPELLIER
%~ UM-2015-2021