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A model with Holstein-like electron-phonon coupling is studied in the limit of adiabatic phonons. The phonon distribution is anharmonic with two degenerate maxima. This model can be related to fermions in a correlated binary alloy and…

Strongly Correlated Electrons · Physics 2007-05-23 K. Ziegler , D. Schneider

We derive the frequency shifts and the broadening of $\Gamma$ point longitudinal optical (LO) and transverse optical (TO) phonon modes, due to electron-phonon interaction, in graphene under uniaxial strain as a function of the electron…

Mesoscale and Nanoscale Physics · Physics 2015-06-19 Mohamed Assili , Sonia Haddad

Properties of phonons - quanta of the crystal lattice vibrations - in graphene have attracted strong attention of the physics and engineering communities. Acoustic phonons are the main heat carriers in graphene near room temperature while…

Mesoscale and Nanoscale Physics · Physics 2015-06-04 Denis L. Nika , Alexander A. Balandin

Using the Boltzmann equation for electrons in metals, we show that the optical phonons soften and have a dispersion due to screening in agreement with the results reported recently [M. Reizer, Phys. Rev. B {\bf 61}, 40 (2000)]. Additional…

Materials Science · Physics 2009-11-07 L. A. Falkovsky

The interactions among lattice, charge, and spin degrees of freedom fundamentally shape material properties. In FeSe, symmetry-breaking perturbations serve as highly sensitive probes of these couplings. Previous work has shown that defects…

We measure the temperature distribution in a biased single-layer graphene transistor using Raman scattering microscopy of the 2D-phonon band. Peak operating temperatures of 1050 K are reached in the middle of the graphene sheet at 210 KW…

We have studied electron scattering by out-of-plane (flexural) phonon modes in doped suspended graphene and its effect on charge transport. In the free-standing case (absence of strain) the flexural branch shows a quadratic dispersion…

Materials Science · Physics 2012-09-14 Héctor Ochoa , Eduardo V. Castro , M. I. Katsnelson , F. Guinea

We have implemented a generic method, based on the 2n+1 theorem within density functional perturbation theory, to calculate the anharmonic scattering coefficients among three phonons with arbitrary wavevectors. The method is used to study…

Materials Science · Physics 2014-06-24 Lorenzo Paulatto , Francesco Mauri , Michele Lazzeri

Our low-temperature magneto-Raman scattering measurements performed on graphene-like locations on the surface of bulk graphite reveal a new series of magneto-phonon resonances involving both K-point and Gamma-point phonons. In particular,…

Mesoscale and Nanoscale Physics · Physics 2016-01-29 D. M. Basko , P. Leszczynski , C. Faugeras , J. Binder , A. A. L. Nicolet , P. Kossacki , M. Orlita , M. Potemski

Interactions with electronic excitations can soften and/or broaden phonons. They are greatly amplified at wavevectors Q+- that connect parallel (nested) sheets of the Fermi surface. In such a case, called a Kohn anomaly, the phonon…

Strongly Correlated Electrons · Physics 2009-09-04 D. Lamago , M. Hoesch , M. Krisch , R. Heid , K. -P. Bohnen , P. Boeni , D. Reznik

We investigate the effect of electron- $\mathrm{A}_{1g}$ phonon coupling on the gapless electronic band dispersion of the pristine graphene. The electron-phonon interaction is introduced through a Kekul\'{e}-type distortion giving rise to…

Mesoscale and Nanoscale Physics · Physics 2013-10-29 B. S. Kandemir , A. Mogulkoc

We present a self-consistent analysis of the photoemission spectral function A(k, w) of graphene monolayers grown epitaxially on SiC(0001). New information derived from spectral intensity anomalies (in addition to linewidths and peak…

Strongly Correlated Electrons · Physics 2008-09-25 Jessica L. McChesney , Aaron Bostwick , Taisuke Ohta , Konstantin Emtsev , Thomas Seyller , Karsten Horn , Eli Rotenberg

One of the salient features of graphene is the very high carrier mobility that implies tremendous potential for use in electronic devices. Unfortunately, transport measurements find the expected high mobility only in freely suspended…

Mesoscale and Nanoscale Physics · Physics 2015-06-04 Søren Ulstrup , Marco Bianchi , Richard Hatch , Dandan Guan , Alessandro Baraldi , Dario Alfè , Liv Hornekær , Philip Hofmann

We calculate the probabilities of two- and four-phonon Raman scattering in graphene and show how the relative intensities of the overtone peaks encode information about relative rates of different inelastic processes electrons are subject…

Mesoscale and Nanoscale Physics · Physics 2009-11-13 D. M. Basko

We present a first-principles study of the temperature- and density-dependent intrinsic electrical resistivity of graphene. We use density-functional theory and density-functional perturbation theory together with very accurate Wannier…

Ultrafast dynamics of graphite is investigated by time-resolved photoemission spectroscopy. We observe spectral features of direct photoexcitations, non-thermal electron distributions, and recovery dynamics occurring with two time scales…

Materials Science · Physics 2011-08-24 Y. Ishida , T. Togashi , K. Yamamoto , M. Tanaka , T. Taniuchi , T. Kiss , M. Nakajima , T. Suemoto , S. Shin

Despite many of the applications of graphene rely on its uneven stiffness and high thermal conductivity, the mechanical properties of graphene, and in general of all 2D materials, are still elusive. The harmonic theory predicts a quadratic…

Intervalley collisions, which scatter electrons from one valley or band to another, can be detrimental to thermoelectric performance in materials with multiple valleys/bands. In this study, density functional theory is used to investigate…

Materials Science · Physics 2023-02-08 Vahid Askarpour , Jesse Maassen

We determine from first-principles the finite-temperature properties--linewidths, line shifts, and lifetimes--of the key vibrational modes that dominate inelastic losses in graphitic materials. In graphite, the phonon linewidth of the…

Materials Science · Physics 2007-10-25 Nicola Bonini , Michele Lazzeri , Nicola Marzari , Francesco Mauri

Inelastic phonon scattering in graphene field-effect transistors (FETs) is studied by numerically solving the Boltzmann transport equation in three dimensional real and phase spaces (x, kx, ky). A kink behavior due to ambipolar transport…

Mesoscale and Nanoscale Physics · Physics 2015-05-27 Jyotsna Chauhan , Jing Guo