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We study a two-terminal graphene Josephson junction with contacts shaped to form a narrow constriction, less than 100nm in length. The contacts are made from type II superconducting contacts and able to withstand magnetic fields high enough…

Mesoscale and Nanoscale Physics · Physics 2019-09-18 M. T. Wei , A. W. Draelos , A. Seredinski , C. T. Ke , H. Li , Y. Mehta , K. Watanabe , T. Taniguchi , M. Yamamoto , S. Tarucha , G. Finkelstein , F. Amet , I. V. Borzenets

We investigated the magnetic field dependence of the Hall and the bend resistances in the ballistic regime for a single layer graphene Hall bar structure containing a pn-junction. When both regions are n-type the Hall resistance dominates…

Mesoscale and Nanoscale Physics · Physics 2013-12-05 S. P. Milovanovic , M. Ramezani Masir , F. M. Peeters

We study the interplay of Klein tunneling (= interband tunneling) between n-doped and p-doped regions in graphene and Andreev reflection (= electron-hole conversion) at a superconducting electrode. The tunneling conductance of an n-p-n…

Mesoscale and Nanoscale Physics · Physics 2007-06-10 A. Ossipov , M. Titov , C. W. J. Beenakker

A graphene sheet partially covered with a bulk superconductor serves as a normal conductor--superconductor (NS) junction, in which electron transport is mainly governed by Andreev reflection (AR). As excess carriers induced over the covered…

Mesoscale and Nanoscale Physics · Physics 2017-06-28 Yositake Takane , Katsuhide Yarimizu , Akinobu Kanda

We study a relativistic quantum cavity system realized by etching out from a graphene sheet by quantum transport measurements and theoretical calculations. The conductance of the graphene cavity has been measured as a function of the back…

Mesoscale and Nanoscale Physics · Physics 2020-02-12 G. Q. Zhang , Xianzhang Chen , Li Lin , Hailin Peng , Zhongfan Liu , Liang Huang , N. Kang , H. Q. Xu

We study the electron/hole transport in puddle-disordered and rough graphene samples which are subject to in-plane magnetic fields. Previous treatments, mostly devoted to regimes where the electron/hole scattering wavelengths are larger…

Mesoscale and Nanoscale Physics · Physics 2015-04-15 R. R. Brandão , L. Moriconi

We present a method for obtaining quantum transport properties in graphene that uniquely combines three crucial features: microscopic treatment of charge disorder, fully quantum mechanical analysis of transport, and the ability to model…

Mesoscale and Nanoscale Physics · Physics 2010-03-12 E. Rossi , J. H. Bardarson , P. W. Brouwer , S. Das Sarma

Near the sample edge, or a sharp magnetic field step the drift of two-dimensional electrons in a magnetic field has the form of skipping/snake orbits. We show that families of skipping/snake orbits of electrons injected at one point inside…

Mesoscale and Nanoscale Physics · Physics 2015-05-28 Nathan Davies , Aavishkar A. Patel , Alberto Cortijo , Vadim Cheianov , Francisco Guinea , Vladimir I. Fal'ko

Graphene consists in a single-layer carbon crystal where 2$p_z$ electrons display a linear dispersion relation in the vicinity of the Fermi level, conveniently described by a massless Dirac equation in $2+1$ spacetime. Spin-orbit effects…

Mesoscale and Nanoscale Physics · Physics 2017-04-04 B. Berche , F. Mireles , E. Medina

In this paper we describe a graphene p-n junction created by chemical doping. We find that chemical doping does not reduce mobility in contrast to top-gating. The preparation technique has been developed from systematic studies about…

Mesoscale and Nanoscale Physics · Physics 2015-05-13 Timm Lohmann , Klaus v. Klitzing , Jurgen H. Smet

Just a few of the promising applications of graphene Corbino pnJ devices include two-dimensional Dirac fermion microscopes, custom programmable quantized resistors, and mesoscopic valley filters. In some cases, device scalability is…

Mesoscale and Nanoscale Physics · Physics 2022-03-15 Chieh-I Liu , Dominick S. Scaletta , Dinesh K. Patel , Mattias Kruskopf , Antonio Levy , Heather M. Hill , Albert F. Rigosi

Characterized by zigzag and armchair boundaries, the narrow ribbons display the very different characteristics in Hall conductivities. It is shown that the multi-band-crossings occur in the energy spectrum for armchair ribbons, and the…

Mesoscale and Nanoscale Physics · Physics 2009-04-02 Junfeng Liu , Zhongshui Ma

Graphene-based Josephson junctions provide a novel platform for studying the proximity effect due to graphene's unique electronic spectrum and the possibility to tune junction properties by gate voltage. Here we describe graphene junctions…

The unusual electronic properties of single-layer graphene make it a promising material system for fundamental advances in physics, and an attractive platform for new device technologies. Graphene's spin transport properties are expected to…

Mesoscale and Nanoscale Physics · Physics 2009-10-23 Mark B. Lundeberg , Joshua A. Folk

Observations of electron-hole asymmetry in transport through graphene devices at high magnetic field challenge prevalent models of the graphene quantum Hall effect. Here, we study this asymmetry both in conventional magnetotransport and in…

Mesoscale and Nanoscale Physics · Physics 2021-11-23 Nicolas Moreau , Boris Brun , Sowmya Somanchi , Kenji Watanabe , Takashi Taniguchi , Christoph Stampfer , Benoît Hackens

We investigate the electron transport in smooth graphene pn junctions, generated by gradually varying electrostatic potentials. The numerically calculated coherent current flow patterns can be understood largely in terms of semi-classical…

Mesoscale and Nanoscale Physics · Physics 2021-01-13 Emmanuel Paredes-Rocha , Yonatan Betancur-Ocampo , Nikodem Szpak , Thomas Stegmann

We study the electronic structure of the junctions between a single graphene layer and carbon nanotubes, using a tight-binding model and the continuum theory based on Dirac fermion fields. The latter provides a unified description of…

Mesoscale and Nanoscale Physics · Physics 2013-05-29 J. Gonzalez , F. Guinea , J. Herrero

We show a dramatic deviation from ergodicity for the conductance fluctuations in graphene. In marked contrast to the ergodicity of dirty metals, fluctuations generated by varying magnetic field are shown to be much smaller than those…

Mesoscale and Nanoscale Physics · Physics 2012-10-19 G. Bohra , R. Somphonsane , N. Aoki , Y. Ochiai , R. Akis , D. K. Ferry , J. P. Bird

The interplay between quantum Hall states and Cooper pairs is usually hindered by the suppression of the superconducting state due to the strong magnetic fields needed to observe the quantum Hall effect. From this point of view graphene is…

Superconductivity · Physics 2015-06-03 Lucian Covaci , Francois Peeters

We examine the possibility that the superconductivity in the newly discovered FeAs materials may be caused by the Coulomb interaction between d-electrons of the iron atoms. We find that when the Hund's rule ferromagnetic interaction is…

Superconductivity · Physics 2009-11-13 Patrick A. Lee , Xiao-Gang Wen