Hybrid Surface-Phonon-Plasmon Polariton Modes in Graphene/Monolayer h‑BN Heterostructures

• Published in: Nano letters Vol. 14; no. 7; pp. 3876 - 3880
• Main Authors: Brar, Victor W, Jang, Min Seok, Sherrott, Michelle, Kim, Seyoon, Lopez, Josue J, Kim, Laura B, Choi, Mansoo, Atwater, Harry
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 09.07.2014
• Subjects: Boron nitride; Collective excitations (including excitons, polarons, plasmons and other charge-density excitations); Condensed matter: electronic structure, electrical, magnetic, and optical properties; Cross-disciplinary physics: materials science; rheology; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Exact sciences and technology; Fullerenes and related materials; diamonds, graphite; Graphene; Joining; Materials science; Monolayers; Nanostructure; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of low-dimensional, mesoscopic, and nanoscale materials and structures; Phonons; Physics; Plasmons; Polaritons; Specific materials; Surface and interface electron states; surface phonon plasmon polariton; Graphene; plasmonics; phonon-induced transparency; plasmon phonon hybridization; boron nitride; strong coupling; Optical phonons; Hexagonal crystals; Dispersion relations; Plasmon polariton interaction; Optical properties; Monolayers; Phonon mode; Hybridization; Surface phonons; Surface plasmons; Heterostructures
• ISSN: 1530-6984; 1530-6992
• DOI: 10.1021/nl501096s

Infrared transmission measurements reveal the hybridization of graphene plasmons and the phonons in a monolayer hexagonal boron nitride (h-BN) sheet. Frequency-wavevector dispersion relations of the electromagnetically coupled graphene plasmon/h-BN phonon modes are derived from measurement of nanoresonators with widths varying from 30 to 300 nm. It is shown that the graphene plasmon mode is split into two distinct optical modes that display an anticrossing behavior near the energy of the h-BN optical phonon at 1370 cm–1. We explain this behavior as a classical electromagnetic strong-coupling with the highly confined near fields of the graphene plasmons allowing for hybridization with the phonons of the atomically thin h-BN layer to create two clearly separated new surface-phonon-plasmon-polariton (SPPP) modes.