Phonon Polaritons in Monolayers of Hexagonal Boron Nitride. Issue 37 (28th July 2019)

• Record Type: Journal Article
• Authors: Dai, Siyuan; Fang, Wenjing; Rivera, Nicholas; Stehle, Yijing; Jiang, Bor‐Yuan; Shen, Jialiang; Tay, Roland Yingjie; Ciccarino, Christopher J.; Ma, Qiong; Rodan‐Legrain, Daniel; Jarillo‐Herrero, Pablo; Teo, Edwin Hang Tong; Fogler, Michael M.; Narang, Prineha; Kong, Jing; Basov, Dimitri N.
• Is Part Of: Advanced materials. Volume 31:Issue 37(2019)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2019-07-28
• Subjects: monolayers -- phonon polaritons -- van der Waals materials; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adma.201806603
• Languages: English
• ISSNs: 0935-9648

Abstract

Abstract: Phonon polaritons in van der Waals materials reveal significant confinement accompanied with long propagation length: important virtues for tasks pertaining to the control of light and energy flow at the nanoscale. While previous studies of phonon polaritons have relied on relatively thick samples, here reported is the first observation of surface phonon polaritons in single atomic layers and bilayers of hexagonal boron nitride (hBN). Using antenna‐based near‐field microscopy, propagating surface phonon polaritons in mono‐ and bilayer hBN microcrystals are imaged. Phonon polaritons in monolayer hBN are confined in a volume about one million times smaller than the free‐space photons. Both the polariton dispersion and their wavelength–thickness scaling law are altered compared to those of hBN bulk counterparts. These changes are attributed to phonon hardening in monolayer‐thick crystals. The data reported here have bearing on applications of polaritons in metasurfaces and ultrathin optical elements. Abstract : Surface phonon polaritons in monolayer and bilayer hexagonal boron nitride are investigated by direct IR nanoimaging. Phonon polaritons in isolated monolayers are highly confined into the single atomic plane and exhibit dispersion properties at variance with hyperbolic phonon polaritons in bulk crystals.