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Graphene has opened new avenues of research in quantum transport, with potential applications for coherent electronics. Coherent transport depends sensitively on scattering from microscopic disorder present in graphene samples: electron…

Mesoscale and Nanoscale Physics · Physics 2015-05-18 Jesse Berezovsky , Robert M Westervelt

We study conductance fluctuations (CF) and the sensitivity of the conductance to the motion of a single scatterer in two-dimensional massless Dirac systems. Our extensive numerical study finds limits to the predicted universal value of CF.…

Mesoscale and Nanoscale Physics · Physics 2013-04-29 Mario F. Borunda , Jesse Berezovsky , Robert M. Westervelt , Eric J. Heller

We study electron transport properties of a monoatomic graphite layer (graphene) with different types of disorder. We show that the transport properties of the system depend strongly on the character of disorder. Away from half filling, the…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 P. M. Ostrovsky , I. V. Gornyi , A. D. Mirlin

Graphene provides a fascinating testbed for new physics and exciting opportunities for future applications based on quantum phenomena. To understand the coherent flow of electrons through a graphene device, we employ a nanoscale probe that…

Mesoscale and Nanoscale Physics · Physics 2010-01-29 J. Berezovsky , M. F. Borunda , E. J. Heller , R. M. Westervelt

We study quantum transport in Dirac materials with a single fermionic Dirac cone (strong topological insulators and graphene in the absence of intervalley coupling) in the presence of non-Gaussian long-range disorder. We show, by directly…

Mesoscale and Nanoscale Physics · Physics 2012-09-04 E. Rossi , J. H. Bardarson , M. S. Fuhrer , S. Das Sarma

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 investigate the amplitude of mesoscopic fluctuations of the differential conductance of a metallic wire at arbitrary bias voltage V. For non-interacting electrons, the variance <delta g^2> increases with V. The asymptotic large-V…

Mesoscale and Nanoscale Physics · Physics 2009-11-10 T. Ludwig , Ya. M. Blanter , A. D. Mirlin

Excess conductance fluctuations with peculiar temperature-dependence from 1.4 to 250 K were observed in curved nano-graphite sheets with an electrode gap length of 300 and 450 nm, whereas the conductance fluctuation is greatly suppressed…

Mesoscale and Nanoscale Physics · Physics 2009-12-31 Haomin Wang , Catherine Choong , Jun Zhang , Kie Leong Teo , Yihong Wu

We solve the Dirac equation, which describes charge massless chiral relativistic carriers in a two-dimensional graphene. We have identified and analysed a novel pseudospin-dependent scattering effect. We compute the tunneling conductance…

Mesoscale and Nanoscale Physics · Physics 2012-11-21 Dima Bolmatov , D. V. Zavialov

Much of the qualitative nature of physical systems can be predicted from the way it scales with system size. Contrary to the continuum expectation, we observe a profound deviation from logarithmic scaling in the impedance of a…

Conductions fluctuations (CF) are studied in single layer graphene devices with superconducting source and drain contacts made from aluminium. The CF are found to be enhanced by superconductivity by a factor of 1.4 to 2. This (near)…

Mesoscale and Nanoscale Physics · Physics 2011-09-19 F. Freitag , J. Trbovic , C. Schönenberger

We study the conductivity of graphene with a smooth but particle-hole-asymmetric disorder potential. Using perturbation theory for the weak-disorder regime and numerical calculations we investigate how the particle-hole asymmetry shifts the…

Mesoscale and Nanoscale Physics · Physics 2016-01-12 Max Hering , Martin Schneider , Piet W. Brouwer

We study the statistics of the reflectance (the ratio of reflected and incident intensities) of an $N$-mode disordered waveguide with weak absorption $\gamma$ per mean free path. Two distinct regimes are identified. The regime $\gamma…

Condensed Matter · Physics 2007-05-23 T. Sh. Misirpashaev , C. W. J. Beenakker

We have performed systematic investigations of transport through graphene on hexagonal boron nitride (hBN) substrates, together with confocal Raman measurements and a targeted theoretical analysis, to identify the dominant source of…

Thermodynamic and transport properties of normal disordered conductors are strongly influenced by the proximity of a superconductor. A cooperation between mesoscopic coherence and Andreev scattering of particles from the superconductor…

Mesoscale and Nanoscale Physics · Physics 2009-10-30 Alexander Altland , B D Simons , D Taras-Semchuk

Mesoscopic conductance fluctuations are a ubiquitous signature of phase-coherent transport in small conductors, exhibiting universal character independent of system details. In this work, however, we demonstrate a pronounced breakdown of…

Magic-angle twisted bilayer graphene is a tunable material with remarkably flat energy bands near the Fermi level, leading to fascinating transport properties and correlated states at low temperatures. However, grown pristine samples of…

Mesoscale and Nanoscale Physics · Physics 2024-03-29 Aleksander Sanjuan Ciepielewski , Jakub Tworzydło , Timo Hyart , Alexander Lau

Conductance fluctuations produced by the presence of disorder in zigzag and armchair graphene nanoribbons are studied. We show that quantum transport in zigzag nanoribbons takes place via edge states which are exponentially localized, as in…

Mesoscale and Nanoscale Physics · Physics 2015-06-17 Ioannis Kleftogiannis , Ilias Amanatidis , Victor A. Gopar

We investigate quantum transport in a normal/superconductor graphene heterostructure, including the possibility of an anisotropic pairing potential in the superconducting region. We find that under certain circumstances, the conductance…

Superconductivity · Physics 2009-11-13 J. Linder , A. Sudbø

We present electron transport measurements on lithographically defined and etched graphene nanoconstrictions with different aspect ratios including different lengths (L) and widths (W). A roughly length-independent disorder induced…

Mesoscale and Nanoscale Physics · Physics 2011-04-13 B. Terrés , J. Dauber , C. Volk , S. Trellenkamp , U. Wichmann , C. Stampfer