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The electron-phonon coupling in potassium-doped graphene on Ir(111) is studied via the renormalization of the pi* band near the Fermi level, using angle-resolved photoemission spectroscopy. The renormalization is found to be fairly weak and…

Mesoscale and Nanoscale Physics · Physics 2010-01-26 M. Bianchi , E. D. L. Rienks , S. Lizzit , A. Baraldi , R. Balog , L. Hornekaer , Ph. Hofmann

Optical pump-terahertz probe differential transmission measurements of as-prepared single layer graphene (AG)(unintentionally hole doped with Fermi energy $E_F$ at $\sim$180 meV), nitrogen doping compensated graphene (NDG) with $E_F$…

Materials Science · Physics 2015-06-22 Srabani Kar , Dipti R. Mohapatra , Eric Freysz , A. K. Sood

"Pumping" of phonons by a dynamic magnetization promises to extend the range and functionality of magnonic devices. We explore the impact of phonon pumping on room-temperature ferromagnetic resonance (FMR) spectra of bilayers of thin…

Mesoscale and Nanoscale Physics · Physics 2022-07-20 Richard Schlitz , Luise Siegl , Takuma Sato , Weichao Yu , Gerrit E. W. Bauer , Hans Huebl , Sebastian T. B. Goennenwein

ZnO is co-doped with Na+ and Si4+ in the ratio 2:1. The ratio was intentionally chosen so that net valence state of dopant theoretically matches that of host. This is to avoid dependence in the amount of oxygen vacancies/interstitials…

Using exact diagonalzation techniques, we study a model of interacting electrons and phonons. The spectral width of the phonons is found to be reduced as the Coulomb interaction U is increased. For a system with two modes per site, we find…

Strongly Correlated Electrons · Physics 2009-10-31 J. E. Han , O. Gunnarsson

Alloying and doping are crucial for enhancing the electronic and optical properties of semiconductors while simultaneously introducing disorder. This report explores the effects of alloying and Si (0.5 at.\%) doping on…

Bi2Sr2CaCu2O{8 + \delta} crystals with varying hole concentrations (0.12 < p < 0.23) were studied to investigate the effects of doping on the symmetry and magnitude of the superconducting gap. Electronic Raman scattering experiments that…

Superconductivity · Physics 2009-10-31 K. C. Hewitt , J. C. Irwin

Electron-phonon coupling (EPC) in bilayer graphene (BLG) at different doping levels is studied by first-principles calculations. The phonons considered are long-wavelength high-energy symmetric (S) and antisymmetric (AS) optical modes. Both…

Materials Science · Physics 2013-03-26 Jia-An Yan , K. Varga , M. Y. Chou

Ab-initio calculations based on density functional theory (DFT) have been performed to study the optical properties of pure graphene and have been compared to that of individual boron (B), nitrogen (N) and BN co-doped graphene sheet. The…

Mesoscale and Nanoscale Physics · Physics 2020-05-22 Pooja Rani , Girija S Dubey , V. K. Jindal

Density functional calculations are used to explain the charge transfer doping mechanism by which species physisorptively bonded to graphene can increase its free hole or electron density, without giving rise to defects, and thus maintain a…

Materials Science · Physics 2017-03-22 Haichang Lu , Yuzheng Guo , John Robertson

Density functional theory calculations have been carried out to investigate single-layer phosphorene functionalized with two kinds of organic molecules, i.e. an electrophilic molecule tetracyano-p-quinodimethane (TCNQ) as electron acceptor…

Mesoscale and Nanoscale Physics · Physics 2014-09-26 Ruiqi Zhang , Bin Li , Jinlong Yang

Two-dimensional (2d) nano-electronics, plasmonics, and emergent phases require clean and local charge control, calling for layered, crystalline acceptors or donors. Our Raman, photovoltage, and electrical conductance measurements combined…

We argue, based on band structure calculations and Eliashberg theory, that the observed decrease of $T_c$ of Al and C doped MgB$_2$ samples can be understood mainly in terms of a band filling effect due to the electron doping by Al and C. A…

Superconductivity · Physics 2007-05-23 Jens Kortus , Oleg V. Dolgov , Reinhard K. Kremer , Alexander A. Golubov

Recent ARPES measurements of single-layer 1H-TaS2 grown on Au(111) suggest strong electron doping from the substrate. In addition, STM/STS measurements on this system show suppression of the charge-density-wave (CDW) instability that occurs…

Materials Science · Physics 2017-06-21 Oliver R. Albertini , Amy Y. Liu , Matteo Calandra

Here we use pristine graphene samples in order to analyze how the Raman peaks intensity, measured at 2.4 eV and 1.96 eV excitation energy, changes with the amount of doping. The use of pristine graphene allows investigating the intensity…

Mesoscale and Nanoscale Physics · Physics 2015-05-14 C. Casiraghi

Graphene is known as the strongest 2D material in nature, yet we show that moderate charge doping of either electrons or holes can further enhance its ideal strength by up to ~17%, based on first principles calculations. This unusual…

Materials Science · Physics 2015-06-11 Chen Si , Wenhui Duan , Zheng Liu , Feng Liu

Fluorite CeO$_2$ doped with group IV elements is studied within the DFT and DFT+U framework. Concentration dependent formation energies are calculated for Ce$_{1-x}$Z$_x$O$_2$ (Z= C, Si, Ge, Sn, Pb, Ti, Zr, Hf) with $0\leq x \leq 0.25$ and…

Materials Science · Physics 2014-02-13 D. E. P. Vanpoucke , S. Cottenier , V. Van Speybroeck , I. Van Driessche , P. Bultinck

Since their discovery, graphene-based systems represent an exceptional playground to explore the emergence of peculiar quantum effects. The present paper focuses on the anomalous appearence of strong infrared phonon resonances in the…

Mesoscale and Nanoscale Physics · Physics 2012-10-04 E. Cappelluti , L. Benfatto , M. Manzardo , A. B. Kuzmenko

Transient reflectivity spectroscopy is widely used to study ultrafast carrier- and phonon-dynamics in semiconductors. In their heterostructures, it is often not straightforward to distinguish contributions to the signal from the various…

Mesoscale and Nanoscale Physics · Physics 2022-02-09 Kunie Ishioka , Ethan Angerhoffer , Christopher J. Stanton , Gerson Mette , Kerstin Volz , Wolfgang Stolz , Ulrich Höfer

We show how coupling to an Einstein phonon $\omega_E$ affects the absorption peaks seen in the optical conductivity of graphene under a magnetic field $B$. The energies and widths of the various lines are shifted, and additional peaks arise…

Mesoscale and Nanoscale Physics · Physics 2015-06-04 Adam Pound , J. P. Carbotte , E. J. Nicol