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Mean-field theories have since long predicted edge magnetism in graphene nanoribbons, where the order parameter is given by the local magnetization. However, signatures of edge magnetism appears elusive in the experiments, suggesting…

Mesoscale and Nanoscale Physics · Physics 2022-07-20 T. Schmirander , D. Pfannkuche , M. Prada

We examine the 1/N expansion, where N is the number of two-component Dirac fermions, for Coulomb interactions in graphene with a gap of magnitude $\Delta = 2 m$. We find that for $N\alpha\gg1$, where $\alpha$ is graphene's "fine structure…

Mesoscale and Nanoscale Physics · Physics 2022-03-07 Valeri N. Kotov , Bruno Uchoa , A. H. Castro Neto

Transport measurements at cryogenic temperatures through a few electron top gated quantum dot fabricated in a silicon/silicon-germanium heterostructure are reported. Variations in gate voltage induce a transition from an isolated dot toward…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 Levente J. Klein , Donald E. Savage , Mark A. Eriksson

In this study, we investigate the charge transport properties of semiconducting armchair graphene nanoribbons (AGNRs) and heterostructures through their topological states (TSs), with a specific focus on the Coulomb blockade region. Our…

Mesoscale and Nanoscale Physics · Physics 2023-07-25 David M T Kuo

We report on Coulomb blockade and Coulomb diamond measurements on an etched, tunable single-layer graphene quantum dot. The device consisting of a graphene island connected via two narrow graphene constrictions is fully tunable by three…

Mesoscale and Nanoscale Physics · Physics 2008-01-24 C. Stampfer , J. Guettinger , F. Molitor , D. Graf , T. Ihn , K. Ensslin

Kane and Mele predicted that in presence of spin-orbit interaction graphene realizes the quantum spin Hall state. However, exceptionally weak intrinsic spin-orbit splitting in graphene ($\approx 10^{-5}$ eV) inhibits experimental…

Mesoscale and Nanoscale Physics · Physics 2013-06-18 Gabriel Autès , Oleg V. Yazyev

We have measured Coulomb drag between an individual single-walled carbon nanotube (SWNT) as a one-dimensional (1D) conductor and the two-dimensional (2D) conductor monolayer graphene, separated by a few-atom-thick boron nitride layer. The…

Mesoscale and Nanoscale Physics · Physics 2021-12-15 Laurel E. Anderson , Austin Cheng , Takashi Taniguchi , Kenji Watanabe , Philip Kim

We propose a mechanism to drive singlet-triplet spin transitions electrically, in a wide class of graphene nanostructures that present pairs of in-gap zero modes, localized at opposite sublattices. Examples are rectangular nanographenes…

Mesoscale and Nanoscale Physics · Physics 2018-05-23 R. Ortiz , N. A. García-Martínez , J. L. Lado , J. Fernández-Rossier

We explore the electronic properties of finite-length graphene nanoribbons as well as graphene nanodisks with various sizes and shapes in quest of metallic ones. For this purpose it is sufficient to search zero-energy states. We find that…

Mesoscale and Nanoscale Physics · Physics 2007-12-15 Motohiko Ezawa

We perform projective quantum Monte Carlo simulations of zigzag graphene nanoribbons within a realistic model with long-range Coulomb interactions. Increasing the relative strength of nonlocal interactions with respect to the on-site…

Strongly Correlated Electrons · Physics 2017-09-29 Marcin Raczkowski , Fakher F. Assaad

We consider a waveguide formed in a clean graphene monolayer by a spatially inhomogeneous magnetic field. The single-particle dispersion relation for this waveguide exhibits a zero-energy Landau-like flat band, while finite-energy bands…

Mesoscale and Nanoscale Physics · Physics 2015-08-21 Laura Cohnitz , Wolfgang Häusler , Alex Zazunov , Reinhold Egger

Based on ab-initio calculations we discuss Kondo effect due to Co adatom on graphene zigzag nanoribbon. Co atom located at hollow site behaves as spin S = 1/2 impurity with dxz and dyz orbitals contributing to magnetic moment. Dynamical…

Mesoscale and Nanoscale Physics · Physics 2015-06-16 Damian Krychowski , Jakub Kaczkowski , Stanislaw Lipinski

In this article we investigate the excitations in a single graphene layer and in a single-walled carbon nanotube, i.e. the spectrum of magnetic excitations is calculated. In the absence of interactions in these systems there is a unique gap…

Strongly Correlated Electrons · Physics 2015-06-19 Vladimir Posvyanskiy , Logi Arnarson , Per Hedegård

We study Coulomb drag in double-layer graphene near the Dirac point. A particular emphasis is put on the case of clean graphene, with transport properties dominated by the electron-electron interaction. Using the quantum kinetic equation…

Mesoscale and Nanoscale Physics · Physics 2013-06-26 M. Schütt , P. M. Ostrovsky , M. Titov , I. V. Gornyi , B. N. Narozhny , A. D. Mirlin

We investigate the nonlinear regime of charge and energy transport through Coulomb-blockaded quantum dots. We discuss crossed effects that arise when electrons move in response to thermal gradients (Seebeck effect) or energy flows in…

Mesoscale and Nanoscale Physics · Physics 2014-09-30 Miguel A. Sierra , David Sanchez

Carbon-based nanostructures and graphene, in particular, evoke a lot of interest as new promising materials for nanoelectronics and spintronics. One of the most important issue in this context is the impact of external electrodes on…

Mesoscale and Nanoscale Physics · Physics 2012-03-16 S. Krompiewski

When electrons are confined in two dimensions and subjected to strong magnetic fields, the Coulomb interactions between them become dominant and can lead to novel states of matter such as fractional quantum Hall liquids. In these liquids…

Mesoscale and Nanoscale Physics · Physics 2015-05-14 Kirill I. Bolotin , Fereshte Ghahari , Michael D. Shulman , Horst L. Stormer , Philip Kim

In the present work, we theoretically study the nonlinear regime of charge transport through a quantum dot coupled to the source and drain reservoirs. The investigation is carried out using a nonequilibrium Green's functions formalism…

Mesoscale and Nanoscale Physics · Physics 2015-12-01 Natalya A. Zimbovskaya

We report transport experiments on graphene quantum dots. We focus on excited state spectra in the near vicinity of the charge neutrality point and signatures of the electron-hole crossover as a function of a perpendicular magnetic field.…

Mesoscale and Nanoscale Physics · Physics 2009-11-19 J. Guettinger , C. Stampfer , T. Frey , T. Ihn , K. Ensslin

The electronic and transport properties of hybrid armchair zigzag nanostructures including U-shaped graphene nanoribbons and patterned nanopores structured graphene were studied using combination of density functional theory and…

Materials Science · Physics 2021-04-05 Nguyen Tien Cuong