Long-Lived Phonon Polaritons in Hyperbolic Materials

Natural hyperbolic materials with dielectric permittivities of opposite signs along different principal axes can confine long-wavelength electromagnetic waves down to the nanoscale, well below the diffraction limit. Confined electromagnetic waves coupled to phonons in hyperbolic dielectrics includin...

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Detalles Bibliográficos
Autores: Ni, Guangxin, McLeod, Alexander S., Sun, Zhiyuan, Matson, Joseph R., Lo, Chiu Fan Bowen, Rhodes, Daniel A., Ruta, Francesco L., Moore, Samuel L., Vitalone, Rocco A., Cuscó, Ramón, Artús, Lluís, Xiong, Lin, Dean, Cory R., Hone, James C., Millis, Andrew J., Fogler, Michael M., Edgar, James H., Caldwell, Joshua D., Basov, D. N.
Tipo de recurso: artículo
Estado:Versión enviada para evaluación y publicación
Fecha de publicación:2021
País:España
Institución:Consejo Superior de Investigaciones Científicas (CSIC)
Repositorio:DIGITAL.CSIC. Repositorio Institucional del CSIC
OAI Identifier:oai:digital.csic.es:10261/244312
Acceso en línea:http://hdl.handle.net/10261/244312
Access Level:acceso abierto
Palabra clave:Phonon polaritons
Van der Waals heterostructures
Hyperbolic materials
Nanoinfrared imaging
Descripción
Sumario:Natural hyperbolic materials with dielectric permittivities of opposite signs along different principal axes can confine long-wavelength electromagnetic waves down to the nanoscale, well below the diffraction limit. Confined electromagnetic waves coupled to phonons in hyperbolic dielectrics including hexagonal boron nitride (hBN) and α-MoO3 are referred to as hyperbolic phonon polaritons (HPPs). HPP dissipation at ambient conditions is substantial, and its fundamental limits remain unexplored. Here, we exploit cryogenic nanoinfrared imaging to investigate propagating HPPs in isotopically pure hBN and naturally abundant α-MoO3 crystals. Close to liquid-nitrogen temperatures, losses for HPPs in isotopic hBN drop significantly, resulting in propagation lengths in excess of 8 μm, with lifetimes exceeding 5 ps, thereby surpassing prior reports on such highly confined polaritonic modes. Our nanoscale, temperature-dependent imaging reveals the relevance of acoustic phonons in HPP damping and will be instrumental in mitigating such losses for miniaturized mid-infrared technologies operating at liquid-nitrogen temperatures.

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