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Using a first-principles approach we calculate the acoustic electron-phonon couplings in graphene for the transverse (TA) and longitudinal (LA) acoustic phonons. Analytic forms of the coupling matrix elements valid in the long-wavelength…

Materials Science · Physics 2013-11-22 Kristen Kaasbjerg , Kristian S. Thygesen , Karsten W. Jacobsen

Based on first-principles calculations and full iterative solution of the linearized Boltzmann-Peierls transport equation for phonons within three-phonon scattering framework, we characterize the lattice thermal conductivities $\kappa$ of…

Materials Science · Physics 2015-06-30 Youdi Kuang , Lucas Lindsay , Sanqiang Shi , Xinjiang Wang , Ruiqiang Guo , Baoling Huang

Ballistic graphene samples in a multimode regime show the sub-Sharvin charge transport, characterized by the conductance reduced by a factor of $\pi/4$ comparing to standard Sharvin contacts in two-dimensional electron gas, and the…

Mesoscale and Nanoscale Physics · Physics 2022-11-02 Adam Rycerz , Piotr Witkowski

A Raman study of a back gated bilayer graphene sample is presented. The changes in the Fermi level induced by charge transfer splits the Raman G-band, hardening its higher component and softening the lower one. These two components are…

Mesoscale and Nanoscale Physics · Physics 2008-12-16 L. M. Malard , D. C. Elias , E. S. Alves , M. A. Pimenta

We calculate the shot noise generated by evanescent modes in graphene for several experimental setups. For two impurity-free graphene strips kept at the Dirac point by gate potentials, separated by a long highly doped region, we find that…

Mesoscale and Nanoscale Physics · Physics 2012-07-13 A. D. Wiener , M. Kindermann

In this work we study the behavior of the optical phonon modes in bilayer graphene devices by applying top gate voltage, using Raman scattering. We observe the splitting of the Raman G band as we tune the Fermi level of the sample, which is…

Mesoscale and Nanoscale Physics · Physics 2012-06-07 D. L. Mafra , P. Gava , L. M. Malard , R. S. Borges , G. G. Silva , J. A. Leon , F. Plentz , F. Mauri , M. A. Pimenta

First-principles calculations of the electronic structure and vibrational modes, in a system of graphene bilayers and trilayers intercalated with alkaline earth atoms, are resented. It is found that, in similarity to the case of…

Superconductivity · Physics 2011-07-12 R. A. Jishi , D. M. Guzman , H. M. Alyahyaei

Theoretical Raman line shape functions have been studied to take care of quantum confinement effect and Fano effect individually and jointly. The characteristics of various Raman line shapes have been studied in terms of the broadening and…

In superconducting copper oxides some Cu-O bond-stretching phonons around 70meV show anomalous giant softening and broadening of electronic origin and electronic dispersions have large renormalization kinks near the same energy. These…

Superconductivity · Physics 2014-01-27 S. R. Park , T. Fukuda , A. Hamann , D. Lamago , L. Pintschovius , M. Fujita , K. Yamada , D. Reznik

Recent scanning tunneling spectroscopy experiments [V. W. Brar et. al., Appl. Phys. Lett. 91, 122102 (2007), Y. Zhang et. al., arXiv:0802.4315 (2008)] on graphene reported an unexpected gap of about $\pm 60$meV around the Fermi level. Here,…

Mesoscale and Nanoscale Physics · Physics 2008-11-26 T. O. Wehling , I. Grigorenko , A. I. Lichtenstein , A. V. Balatsky

We present a Raman study of ZrAs_{2} single crystals, a nodal line semimetal with symmetry-enforced Dirac-like band crossings. We identified the symmetry of phonon modes by polarized light measurements and comparison with calculated phonon…

Materials Science · Physics 2024-05-16 R. Bacewicz , C. Jastrzębski , K. Zberecki , A. S. Wadge , D. Jastrzębski , A. Wiśniewski

Far infrared(FIR) data on the optical properties of graphite are presently lacking. An important step towards filling this gap was taken by Kuzmenko et al. (2008) who measured, on HOPG (Highly Oriented Pyrolitic Graphite) at normal…

Astrophysics of Galaxies · Physics 2015-06-22 Robert J. Papoular , Renaud Papoular

One of the factors limiting electron mobility in supported graphene is remote phonon scattering. We formulate the theory of the coupling between graphene plasmon and substrate surface polar phonon (SPP) modes, and find that it leads to the…

Mesoscale and Nanoscale Physics · Physics 2015-06-05 Zhun-Yong Ong , Massimo V. Fischetti

The optical conductivity of single crystals of Na_xCoO_2 for $x$ = 0.57 is first reported between 295 and 30 K. In the far infrared, an "anomalous Drude" analysis leads to a carrier effective mass of 5 electron masses. That this high value…

Superconductivity · Physics 2009-11-10 S. Lupi , M. Ortolani , P. Calvani

Extensive inelastic neutron scattering measurements of phonons on a single crystal of CaFe2As2 allowed us to establish a fairly complete picture of phonon dispersions in the main symmetry directions. The phonon spectra were also calculated…

We report phonon renormalisation in bilayer graphene as a function of doping. The Raman G peak stiffens and sharpens for both electron and hole doping, as a result of the non-adiabatic Kohn anomaly at the $\Gamma$ point. The bilayer has two…

Mesoscale and Nanoscale Physics · Physics 2015-05-13 A. Das , B. Chakraborty , S. Piscanec , S. Pisana , A. K. Sood , A. C. Ferrari

Magneto-Raman scattering experiments from the surface of graphite reveal novel features associated to purely electronic excitations which are observed in addition to phonon-mediated resonances. Graphene-like and graphite domains are…

Mesoscale and Nanoscale Physics · Physics 2015-05-27 C. Faugeras , M. Amado , P. Kossacki , M. Orlita , M. Kühne , A. A. L. Nicolet , Yu. I. Latyshev , M. Potemski

We report Raman light-scattering and optical conductivity measurements on a single crystal of La(1.775)Sr(0.225)NiO(4) which exhibits incommensurate charge-stripe order. The extra phonon peaks induced by stripe order can be understood in…

We present exact results for the electronic transport properties of graphene sheets connected to two metallic electrodes. Our results, obtained by transfer-matrix methods, are valid for all sheet widths and lengths. In the limit of large…

Mesoscale and Nanoscale Physics · Physics 2015-06-03 Shijie Hu , Wei Du , Guiping Zhang , Miao Gao , Zhong-Yi Lu , Xiaoqun Wang

Optically active defects often play a crucial role in governing the light emission as well as the electronic properties of materials. Moreover, defect-mediated states in the mid-gap region can trap electrons, thus opening a path for the…

Materials Science · Physics 2025-01-03 Aprajita Joshi , Sajid Saikia , Shalini Badola , Angshuman Nag , Surajit Saha