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Probing interlayer coupling in twisted single‐crystal bilayer graphene by Raman spectroscopy
Author(s) -
Yeh ChaoHui,
Lin YungChang,
Nayak Pramoda K.,
Lu ChunChieh,
Liu Zheng,
Suenaga Kazu,
Chiu PoWen
Publication year - 2014
Publication title -
journal of raman spectroscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.748
H-Index - 110
eISSN - 1097-4555
pISSN - 0377-0486
DOI - 10.1002/jrs.4571
Subject(s) - bilayer graphene , raman spectroscopy , graphene , condensed matter physics , bilayer , resonance (particle physics) , materials science , single crystal , van hove singularity , molecular physics , chemistry , optics , nanotechnology , crystallography , physics , electron , atomic physics , fermi level , membrane , biochemistry , quantum mechanics
Twisted bilayer graphene, in which interlayer interaction plays a critical role in this coupled system, is characterized for its angle‐dependent electronic and optical properties. Here, we present a systematic Raman study of single‐crystal twisted bilayer graphene grains, with the spectra of each bilayer graphene precisely correlated to its twist angle using combined transmission electron microscopic technique. Van Hove singularities develop as a result of band rehybridization at the crossing Dirac cones of the two layers, giving rise to a critical twist angle that determines the energy separation between the saddle points in the band structure and the resonance Raman spectra accordingly. The 2D mode becomes sensitive to the twist angle, showing the angle‐dependent position, peak width, and intensity. Our results interpreted in the framework of angle‐dependent double resonance scattering provide an important experimental perspective in understanding the coupled bilayer graphene system. Copyright © 2014 John Wiley & Sons, Ltd.