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Cuscó R, Edgar JH, Liu S, Li J, Artús L. Isotopic Disorder: The Prevailing Mechanism in Limiting the Phonon Lifetime in Hexagonal BN. PHYSICAL REVIEW LETTERS 2020; 124:167402. [PMID: 32383900 DOI: 10.1103/physrevlett.124.167402] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Accepted: 04/08/2020] [Indexed: 06/11/2023]
Abstract
The phonon linewidth of isotopically controlled hexagonal boron nitride (h-BN) single crystals has been determined by Raman scattering. The scattering by isotopic mass disorder induces a phonon broadening that is largest for boron 11 fractions around 0.65. Lowest-order perturbation theory does not suffice to explain the dependence of the isotopic broadening on isotopic composition. A multiple-scattering theory based on the coherent potential approximation provides a good quantitative account of the phonon shift and broadening with isotopic composition observed in the experiments. Isotopic-disorder scattering is shown to have a prominent role in limiting the optical-phonon lifetime in h-BN.
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Affiliation(s)
- Ramon Cuscó
- Institut Jaume Almera (ICTJA-CSIC), Consejo Superior de Investigaciones Científicas, Lluís Solé i Sabarís s.n., 08028 Barcelona, Spain
| | - James H Edgar
- Tim Taylor Department of Chemical Engineering, Kansas State University, Manhattan, Kansas 66506, USA
| | - Song Liu
- Tim Taylor Department of Chemical Engineering, Kansas State University, Manhattan, Kansas 66506, USA
| | - Jiahan Li
- Tim Taylor Department of Chemical Engineering, Kansas State University, Manhattan, Kansas 66506, USA
| | - Luis Artús
- Institut Jaume Almera (ICTJA-CSIC), Consejo Superior de Investigaciones Científicas, Lluís Solé i Sabarís s.n., 08028 Barcelona, Spain
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2
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Giles AJ, Dai S, Vurgaftman I, Hoffman T, Liu S, Lindsay L, Ellis CT, Assefa N, Chatzakis I, Reinecke TL, Tischler JG, Fogler MM, Edgar JH, Basov DN, Caldwell JD. Ultralow-loss polaritons in isotopically pure boron nitride. NATURE MATERIALS 2018; 17:134-139. [PMID: 29251721 DOI: 10.1038/nmat5047] [Citation(s) in RCA: 147] [Impact Index Per Article: 24.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2017] [Accepted: 11/01/2017] [Indexed: 05/20/2023]
Abstract
Conventional optical components are limited to size scales much larger than the wavelength of light, as changes to the amplitude, phase and polarization of the electromagnetic fields are accrued gradually along an optical path. However, advances in nanophotonics have produced ultrathin, so-called 'flat' optical components that beget abrupt changes in these properties over distances significantly shorter than the free-space wavelength. Although high optical losses still plague many approaches, phonon polariton (PhP) materials have demonstrated long lifetimes for sub-diffractional modes in comparison to plasmon-polariton-based nanophotonics. We experimentally observe a threefold improvement in polariton lifetime through isotopic enrichment of hexagonal boron nitride (hBN). Commensurate increases in the polariton propagation length are demonstrated via direct imaging of polaritonic standing waves by means of infrared nano-optics. Our results provide the foundation for a materials-growth-directed approach aimed at realizing the loss control necessary for the development of PhP-based nanophotonic devices.
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Affiliation(s)
| | - Siyuan Dai
- Department of Physics, University of California San Diego, San Diego, La Jolla, California 92093, USA
| | - Igor Vurgaftman
- United States Naval Research Laboratory, Washington DC 20375, USA
| | - Timothy Hoffman
- Department of Chemical Engineering, Kansas State University, Manhattan, Kansas 66506, USA
| | - Song Liu
- Department of Chemical Engineering, Kansas State University, Manhattan, Kansas 66506, USA
| | - Lucas Lindsay
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, USA
| | - Chase T Ellis
- United States Naval Research Laboratory, Washington DC 20375, USA
| | | | | | | | | | - Michael M Fogler
- Department of Physics, University of California San Diego, San Diego, La Jolla, California 92093, USA
| | - J H Edgar
- Department of Chemical Engineering, Kansas State University, Manhattan, Kansas 66506, USA
| | - D N Basov
- Department of Physics, University of California San Diego, San Diego, La Jolla, California 92093, USA
- Department of Physics, Columbia University, New York, New York 10027, USA
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Werheit H, Filipov V, Shitsevalova N, Armbrüster M, Schwarz U. Isotopic phonon effects in LaB6-LaB6 do not possess cubic symmetry and show a non-random isotope distribution. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2012; 24:385405. [PMID: 22945638 DOI: 10.1088/0953-8984/24/38/385405] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The isotopic phonon effects in LaB(6) are investigated on the Raman spectra of a series of high-quality single crystals with systematically varied contents of (10)B and (11)B isotopes. A detailed group theoretical analysis enlightens the correlation between distortions of the B(6) octahedra and the splitting or broadening of phonon modes. It is evident that LaB(6) does not have cubic symmetry as assumed so far. A further symmetry reduction of the B(6) octahedra occurs in isotopically mixed crystals. There, the distribution of isotopes is not random as commonly assumed; the probability of associating equal isotopes increases with their mass decreasing.
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Affiliation(s)
- H Werheit
- Institute of Physics, University Duisburg-Essen, Duisburg, Germany.
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Seeger T, Fuente GDL, Maser W, Benito A, Righi A, Sauvajol J, Martínez MT. Incorporation of Multi Wall Carbon Nanotubes into Glass-Surfaces via Laser-Treatment. ACTA ACUST UNITED AC 2011. [DOI: 10.1557/proc-772-m2.8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
AbstractCarbon nanotubes (CNT) are interesting candidates for the reinforcement in robust composites and for conducting fillers in polymers due to their fascinating electronic and mechanical properties. For the first time, we report the incorporation of multi walled carbon nanotubes (MWNTs) into silica-glass surfaces by means of partial surface-melting caused by a continuous wave Nd:YAG laser. MWNTs were detected being well incorporated in the silica-surface. The composites are characterized using scanning electron microscopy (SEM) and Raman-spectroscopy. A model for the composite-formation is proposed based on heatabsorption by MWNTs and a partial melting of the silica-surface.
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