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We present a systematic Raman study of unconventionally-stacked double-layer graphene, and find that the spectrum strongly depends on the relative rotation angle between layers. Rotation-dependent trends in the position, width and intensity…

Mesoscale and Nanoscale Physics · Physics 2012-06-15 Kwanpyo Kim , Sinisa Coh , Liang Z. Tan , William Regan , Jong Min Yuk , Eric Chatterjee , M. F. Crommie , Marvin L. Cohen , Steven G. Louie , A. Zettl

We investigate the quality of hydrogen plasma defined graphene edges by Raman spectroscopy, atomic resolution AFM and low temperature electronic transport measurements. The exposure of graphite samples to a remote hydrogen plasma leads to…

In this study, we determined the chiral direction of the quantum-Hall (QH) edge states in graphene by adopting simple two-terminal conductance measurements while grounding different edge positions of the sample. The edge state with a…

Mesoscale and Nanoscale Physics · Physics 2012-03-05 Dong-Keun Ki , Sanghyun Jo , Hu-Jong Lee

We investigated Raman spectra of single-layer and multi-layer graphene under ultraviolet laser excitation at the wavelength of 325 nm. It was found that while the G peak of graphene remains pronounced in UV Raman spectra, the 2D band…

Materials Science · Physics 2015-05-13 Irene Calizo , Igor Bejenari , Muhammad Rahman , Guanxiong Liu , Alexander A. Balandin

Results of room temperature Raman scattering studies of ultrathin graphitic films supported on Si (111)/SiO2 substrates are reported. The results are significantly different from those known for graphite. Spectra were collected using 514 nm…

Mesoscale and Nanoscale Physics · Physics 2015-06-25 Awnish Gupta , Gugang Chen , P. Joshi , S. Tadigadapa , P. C. Eklund

In this paper, optical properties of Chiral Graphene Nanoribbons both in longitude and transverse polarization have been studied using density functional theory calculation. It has been shown that the selection rule which have been reported…

Mesoscale and Nanoscale Physics · Physics 2012-05-22 M. Berahman , M. Asad , M. H. Sheikhi

Using a model Hamiltonian approach including electron-electron interactions, we systematically investigate the electronic structure and magnetic properties of chiral graphene nanoribbons. We show that the presence of magnetic edge states is…

Mesoscale and Nanoscale Physics · Physics 2011-09-13 Oleg V. Yazyev , Rodrigo B. Capaz , Steven G. Louie

This study examines the roughness of mechanically cleaved edges in 2D crystals and glasses using molecular dynamics simulations with chemically accurate machine-learning force fields. Our results show that ultra-flat armchair and zigzag…

Materials Science · Physics 2024-07-22 Pengjie Shi , Zhiping Xu

We present a Raman study of Ar(+)-bombarded graphene samples with increasing ion doses. This allows us to have a controlled, increasing, amount of defects. We find that the ratio between the D and G peak intensities for a given defect…

We report an atomically-resolved scanning tunneling microscopy (STM) investigation of the edges of graphene grains synthesized on Cu foils by chemical vapor deposition (CVD). Most of the edges are macroscopically parallel to the zigzag…

Mesoscale and Nanoscale Physics · Physics 2011-09-20 Jifa Tian , Helin Cao , Wei Wu , Qingkai Yu , Yong P. Chen

We investigated the atomic structures, Raman spectroscopic and electrical transport properties of individual graphene nanoribbons (GNRs, widths ~10-30 nm) derived from sonochemical unzipping of multi-walled carbon nanotubes (MWNTs).…

Materials Science · Physics 2011-06-21 Liming Xie , Hailiang Wang , Chuanhong Jin , Xinran Wang , Liying Jiao , Kazu Suenaga , Hongjie Dai

The authors report micro-Raman investigation of changes in the single and bilayer graphene crystal lattice induced by the low and medium energy electron-beam irradiation (5 and 20 keV). It was found that the radiation exposures results in…

Materials Science · Physics 2009-11-13 Desalegne Teweldebrhan , Alexander A. Balandin

The X-ray edge singularity of bilayer graphene is studied by generalizing the path integral approach based on local action which was employed for monolayer graphene. In sharp contrast to the case of monolayer graphene, the bilayer graphene…

Strongly Correlated Electrons · Physics 2015-05-20 Hyun C. Lee

We compare the main feature of the measured Raman scattering spectra from single layer graphene with a bilayer in which the two layers are arbitrarily misoriented. The profiles of the 2D bands are very similar having only one component,…

Mesoscale and Nanoscale Physics · Physics 2009-11-13 Philippe Poncharal , Anthony Ayari , Thierry Michel , Jean-Louis Sauvajol

In this work, we study the Raman spectra of twisted bilayer graphene samples as a function of their twist-angles ($\theta$), ranging from 0.03$^\circ$ to 3.40$^\circ$, where local $\theta$ are determined by analysis of their associated…

We show how the two-dimensional Dirac oscillator model can describe some properties of electrons in graphene. This model explains the origin of the left-handed chirality observed for charge carriers in monolayer and bilayer graphene. The…

Mesoscale and Nanoscale Physics · Physics 2013-11-21 C. Quimbay , P. Strange

We show the evolution of Raman spectra with number of graphene layers on different substrates, SiO$_{2}$/Si and conducting indium tin oxide (ITO) plate. The G mode peak position and the intensity ratio of G and 2D bands depend on the…

Materials Science · Physics 2007-10-24 Anindya Das , Biswanath Chakraborty , A. K. Sood

The small mass and atomic-scale thickness of graphene membranes make them highly suitable for nanoelectromechanical devices such as e.g. mass sensors, high frequency resonators or memory elements. Although only atomically thick, many of the…

We investigate graphene and graphene layers on different substrates by monochromatic and white-light confocal Rayleigh scattering microscopy. The image contrast depends sensitively on the dielectric properties of the sample as well as the…

Materials Science · Physics 2008-01-07 C. Casiraghi , A. Hartschuh , E. Lidorikis , H. Qian , H. Harutyunyan , T. Gokus , K. S. Novoselov , A. C. Ferrari

We present a systematic experimental and theoretical study of the two-phonon (2D) Raman scattering in graphene under uniaxial tension. The external perturbation unveils that the 2D mode excited with 785nm has a complex line-shape mainly due…