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Graphene is an attractive electrode material to contact nanostructures down to the molecular scale since it can be gated electrostatically. Gating can be used to control the doping and the energy level alignment in the nanojunction, thereby…

Mesoscale and Nanoscale Physics · Physics 2016-01-20 Nick R. Papior , Tue Gunst , Daniele Stradi , Mads Brandbyge

Avoiding charge density variations and impurities in graphene is vital for high-quality graphene-based devices. Here, we demonstrate an optical method using Raman 2D peak-split to monitor charge density variations in the range 1-25e10 cm-2.…

Applied Physics · Physics 2020-05-12 Zhuofa Chen , Nathan Ullberg , Mounika Vutukuru , David Barton , Anna K Swan

Magneto Raman scattering study of the E$_{2g}$ optical phonons in multi-layer epitaxial graphene grown on a carbon face of SiC are presented. At 4.2K in magnetic field up to 33 T, we observe a series of well pronounced avoided crossings…

Materials Science · Physics 2015-05-13 C. Faugeras , M. Amado , P. Kossacki , M. Orlita , M. Sprinkle , C. Berger , W. A. de Heer , M. Potemski

In this work, we present an investigation regarding how and why molecular hydrogen changes the electronic properties of graphene field effect transistors. We demonstrate that interaction with H2 leads to local doping of graphene near of the…

Using in-situ Raman scattering from phosphorene channel in an electrochemically top-gated field effect transistor, we show that its phonons with A$_g$ symmetry depend much more strongly on concentration of electrons than that of holes,…

High quality epitaxial graphene films can be applied as templates for tailoring graphene-substrate interfaces that allow for precise control of the charge carrier behavior in graphene through doping and many-body effects. By combining…

Electron-doped high-Tc FeSe reportedly has a strong electron correlation that is enhanced with doping. It has been noticed that significant electric fields exist inevitably between FeSe and external donors along with electron transfer.…

Strongly Correlated Electrons · Physics 2019-02-04 Young Woo Choi , Hyoung Joon Choi

Suspended graphene exhibits ripples of size ranging from 50 to 100 {\AA} and height $\sim$10{\AA}, however, their origin remains undetermined. Previous theoretical works have proposed that rippling in graphene might be generated by the…

Mesoscale and Nanoscale Physics · Physics 2020-07-08 Tommaso Cea , Miguel Ruiz-Garcia , Luis Bonilla , Francisco Guinea

We study how the Fermi energy of a graphene monolayer separated from a conducting substrate by a dielectric spacer depends on the properties of the substrate and on an applied voltage. An analytical model is developed that describes the…

Mesoscale and Nanoscale Physics · Physics 2013-02-21 Menno Bokdam , Petr A. Khomyakov , Geert Brocks , Paul J. Kelly

We report strong electron-phonon coupling in magic-angle twisted bilayer graphene (MA-TBG) obtained from atomistic description of the system including more than 10000 atoms in the moire supercell. Electronic structure, phonon spectrum, and…

Mesoscale and Nanoscale Physics · Physics 2018-12-27 Young Woo Choi , Hyoung Joon Choi

Doping of semiconductors is essential in modern electronic and photonic devices. While doping is well understood in bulk semiconductors, the advent of carbon nanotubes and nanowires for nanoelectronic and nanophotonic applications raises…

Materials Science · Physics 2015-05-18 Catalin D. Spataru , François Léonard

We demonstrated theoretically that the renormalization of the electron energy spectrum near the Dirac point of graphene by a strong high-frequency electromagnetic field (dressing field) drastically depends on polarization of the field.…

Mesoscale and Nanoscale Physics · Physics 2016-02-04 K. Kristinsson , O. V. Kibis , S. Morina , I. A. Shelykh

In this work, we study the in-plane optical phonon modes of current-carrying single-layer graphene whose coupling to the $\pi$ electron gas is strong. Such modes are expected to undergo a frequency shift compared to the non-current-carrying…

Mesoscale and Nanoscale Physics · Physics 2022-06-07 Mohsen Sabbaghi , Tobias Stauber , Hyun-Woo Lee , J. Sebastian Gomez-Diaz , George W. Hanson

We consider an electron-acoustic phonon coupling mechanism associated with the dependence of crystal dielectric permittivity on the strain (the so-called Pekar mechanism) in nanostructures characterized by strong confining electric fields.…

Mesoscale and Nanoscale Physics · Physics 2009-11-10 B. A. Glavin , V. A. Kochelap , T. L. Linnik , K. W. Kim

We study the effect exerted by the electrons on the flexural phonons in graphene, accounting for the attractive interaction created by the exchange of electron-hole excitations. Combining the self-consistent computation of the phonon…

Mesoscale and Nanoscale Physics · Physics 2010-03-18 Pablo San-Jose , Jose González , Francisco Guinea

We have formulated a theory for investigating the conditions which are required to achieve entangled states of electrons on graphene and three-dimensional (3D) topological insulators (TIs). We consider the quantum entanglement of spins by…

Mesoscale and Nanoscale Physics · Physics 2015-06-16 Andrii Iurov , Godfrey Gumbs

We analyze the effect of electron-phonon coupling on photoemission properties and ultrafast response of doped monolayer MoS2. The analysis is based on combined DFT and many-body (Eliashberg theory) approaches. In particular, we have…

Materials Science · Physics 2015-02-02 Neha Nayyar , Duy Le , Volodymyr Turkowski , Talat S. Rahman

The limited quantum yield of strained monolayer transition metal dichalcogenides grown by vapor-phase methods and during transfer-based stacking poses a fundamental challenge for their optoelectronic applications. Here, we introduce the…

Kohn anomalies in three-dimensional metallic crystals are dips in the phonon dispersion that are caused by abrupt changes in the screening of the ion-cores by the surrounding electron-gas. These anomalies are also present at the…

Mesoscale and Nanoscale Physics · Physics 2013-11-19 F. Forster , A. Molina-Sanchez , S. Engels , A. Epping , K. Watanabe , T. Taniguchi , L. Wirtz , C. Stampfer

We demonstrate that the plasmon frequency and Drude weight of the electron liquid in a doped graphene sheet are strongly renormalized by electron-electron interactions even in the long-wavelength limit. This effect is not captured by the…

Mesoscale and Nanoscale Physics · Physics 2011-07-19 Saeed H. Abedinpour , G. Vignale , A. Principi , Marco Polini , Wang-Kong Tse , A. H. MacDonald