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Tunable Phonon Polaritons in Atomically Thin van der Waals Crystals of Boron Nitride

TitleTunable Phonon Polaritons in Atomically Thin van der Waals Crystals of Boron Nitride
Publication TypeJournal Article
Year of Publication2014
AuthorsDai, S., Fei Z., Ma Q., Rodin A. S., Wagner M., {McLeod} A. S., Liu M. K., Gannett W., Regan W., Watanabe K., Taniguchi T., Thiemens M., Dominguez G., Neto Castro A. H., Zettl A., Keilmann F., Jarillo-Herrero P., Fogler M. M., and Basov D. N.
Date Published03/2014
ISSN0036-8075, 1095-9203

van der Waals heterostructures assembled from atomically thin crystalline layers of diverse two-dimensional solids are emerging as a new paradigm in the physics of materials. We used infrared nanoimaging to study the properties of surface phonon polaritons in a representative van der Waals crystal, hexagonal boron nitride. We launched, detected, and imaged the polaritonic waves in real space and altered their wavelength by varying the number of crystal layers in our specimens. The measured dispersion of polaritonic waves was shown to be governed by the crystal thickness according to a scaling law that persists down to a few atomic layers. Our results are likely to hold true in other polar van der Waals crystals and may lead to new functionalities. Nanoimaged Polaritons Engineered heterostructures consisting of thin, weakly bound layers can exhibit many attractive electronic properties. Dai et al. (p. 1125) used infrared nanoimaging on the surface of hexagonal boron nitride crystals to detect phonon polaritons, collective modes that originate in the coupling of photons to optical phonons. The findings reveal the dependence of the polariton wavelength and dispersion on the thickness of the material down to just a few atomic layers.


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