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We theoretically study the electronic transport properties of Dirac fermions through one and double triangular barriers in graphene. Using the transfer matrix method, we determine the transmission, conductance and Fano factor. They are…

Mesoscale and Nanoscale Physics · Physics 2015-06-15 Abderrahim El Mouhafid , Ahmed Jellal

Electrons are offered a valley degree of freedom in presence of particular lattice structures. Manipulating valley degeneracy is the subject matter of an emerging field of investigation, mostly focused on charge transport in graphene. In…

Strongly Correlated Electrons · Physics 2012-04-18 Zengwei Zhu , Aurelie Collaudin , Benoit Fauque , Woun Kang , Kamran Behnia

The electrons found in Dirac materials are notorious for being difficult to manipulate due to the Klein phenomenon and absence of backscattering. Here we investigate how spatial modulations of the Fermi velocity in two-dimensional Dirac…

Mesoscale and Nanoscale Physics · Physics 2017-07-10 C. A. Downing , M. E. Portnoi

Dirac electrons in graphene have a valley degree of freedom that is being explored as a carrier of information. In that context of "valleytronics" one seeks to coherently manipulate the valley index. Here we show that reflection from a…

Mesoscale and Nanoscale Physics · Physics 2018-09-12 C. W. J. Beenakker , N. V. Gnezdilov , E. Dresselhaus , V. P. Ostroukh , Y. Herasymenko , I. Adagideli , J. Tworzydlo

In graphene, the valleys represent spin-like quantities and can act as a physical resource in valley-based electronics to novel quantum computation schemes. Here we demonstrate a direct route to tune and read the valley quantum states of…

Mesoscale and Nanoscale Physics · Physics 2012-06-19 Atindra Nath Pal , Vidya Kochat , Arindam Ghosh

We present electronic structure and quantum transport calculations that predict conducting channels induced in graphene quantum dots by lines of adsorbed hydrogen atoms to function as highly efficient, experimentally realizable valley…

Mesoscale and Nanoscale Physics · Physics 2019-09-30 Mohammadhadi Azari , George Kirczenow

Valley degrees of freedom offer a potential resource for quantum information processing if they can be effectively controlled. We discuss an optical approach to this problem in which intense light breaks electronic symmetries of a…

Mesoscale and Nanoscale Physics · Physics 2016-01-11 Arijit Kundu , H. A. Fertig , Babak Seradjeh

In this work we study theoretically the electronic properties of a sheet of graphene grown on a periodic heterostructure substrate. We write an effective Dirac equation, which includes a dependence of both the band gap and the Fermi…

Materials Science · Physics 2014-11-12 Jonas R. F. Lima , F. Moraes

The valley transport properties of a superlattice of out-of-plane Gaussians deformations are calculated using a Green's function and a Machine Learning approach. Our results show that periodicity significantly improves the valley filter…

Mesoscale and Nanoscale Physics · Physics 2019-11-14 V. Torres , P. Silva , E. A. T. de Souza , L. A. Silva , D. A. Bahamon

Experimental realization of efficient graphene-based absorbers is a challenging task due to the low carrier mobility in processed graphene. In this paper, we circumvent this problem by placing uniform graphene sheets on metallic…

Applied Physics · Physics 2020-03-24 Xuchen Wang , Sergei A. Tretyakov

The time evolution of a wavepacket in strained graphene is studied within the tight-binding model and continuum model. The effect of an external magnetic field, as well as a strain-induced pseudo-magnetic field, on the wave packet…

Mesoscale and Nanoscale Physics · Physics 2011-05-06 Andrey Chaves , L. Covaci , Kh. Yu. Rakhimov , G. A. Farias , F. M. Peeters

An analogue of the Datta-Das spin FET is investigated, which is all-graphene and based on the valley degree of freedom of electrons / holes. The "valley FET" envisioned consists of a quantum wire of gapped graphene (channel) sandwiched…

Mesoscale and Nanoscale Physics · Physics 2013-01-01 M. -K. Lee , N. -Y. Lue , Y. -C. Chen , C. -K. Wen , G. Y. Wu

Motivated by the idea of smart metasurfaces, we will demonstrate a graphene-based tunable absorber in which perfect absorption can be achieved for all angles of incidence, only by tuning the Fermi level of graphene. We place an unpatterned…

Applied Physics · Physics 2018-03-23 Xu-Chen Wang , Sergei A. Tretyakov

Quantum transport calculations describing electron scattering off an extended line defect in graphene are presented. The calculations include potentials from local magnetic moments recently predicted to exist on sites adjacent to the line…

Mesoscale and Nanoscale Physics · Physics 2012-05-18 Daniel Gunlycke , Carter T. White

The interplay of massive electrons with spin-orbit coupling in bulk graphene results in a spin-valley dependent gap. Thus, a barrier with such properties can act as a filter, transmitting only opposite spins from opposite valleys. In this…

Mesoscale and Nanoscale Physics · Physics 2014-07-25 Marko M. Grujić , Milan Ž. Tadić , François M. Peeters

At low energy, electrons in doped graphene sheets behave like massless Dirac fermions with a Fermi velocity which does not depend on carrier density. Here we show that modulating a two-dimensional electron gas with a long-wavelength…

Mesoscale and Nanoscale Physics · Physics 2009-06-29 M. Gibertini , A. Singha , V. Pellegrini , M. Polini , G. Vignale , A. Pinczuk , L. N. Pfeiffer , K. W. West

Two dimensional (2D) materials provide a unique platform to explore the full potential of magnetic proximity driven phenomena, which can be further used for applications in next generation spintronic devices. Of particular interest is to…

We show that the angular range of the transmission through magnetic barrier structures can be efficiently controlled in single-layer and bilayer graphenes and this renders the structure's efficient wavevector filters. As the number of…

Mesoscale and Nanoscale Physics · Physics 2009-07-22 M. Ramezani Masir , P. Vasilopoulos , F. M. Peeters

We study graphene with an adsorbed spin texture, where the localized spins create a periodic magnetic flux. The latter produces gaps in the graphene spectrum and breaks the valley symmetry. The resulting effective electronic model, which is…

Materials Science · Physics 2011-03-31 Antonio Hill , Andreas Sinner , Klaus Ziegler

The group delay time of Dirac fermions subjected to a tilting barrier potential along the $ x $-axis is investigated in graphene. We start by finding the eigenspinor solution of the Dirac equation and then relating it to incident,…

Mesoscale and Nanoscale Physics · Physics 2022-09-07 Youssef Fattasse , Miloud Mekkaoui , Ahmed Jellal , Abdelhadi Bahaoui