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We present electronic structure calculations of twisted double bilayer graphene (TDBG): A tetralayer graphene structure composed of two AB-stacked graphene bilayers with a relative rotation angle between them. Using first-principles…

Mesoscale and Nanoscale Physics · Physics 2019-11-05 F. J. Culchac , Rodrigo B. Capaz , Leonor Chico , E. Suarez Morell

Evidence of flat-band magnetism and half-metallicity in compressed twisted bilayer graphene is provided with first-principles calculations. We show that dynamic band-structure engineering in twisted bilayer graphene is possible by…

Materials Science · Physics 2019-06-05 Alejandro Lopez-Bezanilla

We perform density functional calculations on one-dimensional zigzag edge graphene nano-ribbons (ZGNRs) of different widths, with and without edge doping including semi-local exchange-correlations. Our study reveals that, although the…

Materials Science · Physics 2008-06-13 Sudipta Dutta , Swapan K. Pati

Understanding the magnetic response of the normal state of the cuprates is considered a key piece in solving the puzzle of their high-temperature superconductivity. The essential physics of these materials is believed to be captured by the…

Using exact quantum Monte Carlo method, we examine the recent novel electronic states seen in magic-angle graphene superlattices. From the Hubbard model on a double-layer honeycomb lattice with a rotation angle $\theta=1.08^{\circ}$, we…

Superconductivity · Physics 2019-03-07 Tongyun Huang , Lufeng Zhang , Tianxing Ma

An energy gap can be opened in the electronic spectrum of graphene by lifting its sublattice symmetry. In bilayers, it is possible to open gaps as large as 0.2 eV. However, these gaps rarely lead to a highly insulating state expected for…

We investigate electronic band structure and transport properties in bilayer graphene superlattices of Thue-Morse sequence. It is interesting to find that the zero-$\bar{k}$ gap center is sensitive to interlayer coupling $t'$, and the…

Strongly Correlated Electrons · Physics 2013-10-30 Changan Li , Hemeng Cheng , Ruofan Chen , Tianxing Ma , Li-Gang Wang , Yun Song , Hai-Qing Lin

Motivated by the recently experimental reported signatures of the tunable Mott insulating state and superconductivity in an ABC graphene trilayer superlattice, we investigate the charge compressibility, the spin correlation, and the…

Strongly Correlated Electrons · Physics 2021-07-09 Huijia Dai , Junchen Hou , Xiao Zhang , Ying Liang , Tianxing Ma

We study theoretically the coherent electron focusing in graphene nanoribbons. Using semiclassical and numerical tight binding calculations we show that perfect armchair edges give rise to equidistant peaks in the focusing spectrum. In the…

Mesoscale and Nanoscale Physics · Physics 2010-03-22 Peter Rakyta , Andor Kormanyos , Jozsef Cserti , Pekka Koskinen

Electronic band gap and transport in quasi-periodic graphene superlattice of double-periodic sequence have been investigated. It is found that such quasi-periodic structure can possess a zero-averaged wave number (zero-$\bar{k}$) gap which…

Mesoscale and Nanoscale Physics · Physics 2012-11-29 Xi Chen , Pei-Liang Zhao , Qi-Biao Zhu

Motivated by the experimental detection of superconductivity in the low-carrier density half-Heusler compound YPtBi, we study the pairing instabilities of three-dimensional strongly spin-orbit coupled semimetals with a quadratic band…

Superconductivity · Physics 2018-01-03 Lucile Savary , Jonathan Ruhman , Jörn W. F. Venderbos , Liang Fu , Patrick A. Lee

We study the electronic and transport properties of a graphene-based superlattice theoretically by using an effective Dirac equation. The superlattice consists of a periodic potential applied on a single-layer graphene deposited on a…

Mesoscale and Nanoscale Physics · Physics 2015-02-26 Jonas R. F. Lima

Hydrogenated graphene, graphane, is studied on oxygen-terminated silicon dioxide substrate using ab initio calculations. A structure with hydrogenation only on one side of the graphene layer is found stable and its hydrogen configurations…

Mesoscale and Nanoscale Physics · Physics 2011-07-13 M. Ijäs , P. Havu , A. Harju , P. Pasanen

The bands of graphite are extremely sensitive to topological defects which modify the electronic structure. In this paper we found non-dispersive flat bands no farther than 10 meV of the Fermi energy in slightly twisted bilayer graphene as…

Mesoscale and Nanoscale Physics · Physics 2010-12-21 E. Suárez Morell , J. D. Correa , P. Vargas , M. Pacheco , Z. Barticevic

Starting from a continuum-model description, we develop a microscopic weak-coupling theory for superconductivity in twisted double-bilayer graphene. We study both electron-phonon and entirely electronic pairing mechanisms. In each case, the…

Superconductivity · Physics 2020-08-04 Rhine Samajdar , Mathias S. Scheurer

Electronic properties of two-dimensional graphene superlattice made with partial hydrogenation were thoroughly studied via Density Functional Tight Binding approach (DFTB) which incorporates the tight-binding method into the density…

Mesoscale and Nanoscale Physics · Physics 2015-05-18 Ming Yang , Argo Nurbawono , Chun Zhang , Ariando , Yuan Ping Feng

Using density functional theory calculations, we have studied the edge-functionalization of armchair graphene nanoribbons (AGNRs) with pentagonal-hexagonal edge structures. While the AGNRs with pentagonal-hexagonal edge structures (labeled…

Mesoscale and Nanoscale Physics · Physics 2020-02-05 Junga Ryou , Jinwoo Park , Gunn Kim , Suklyun Hong

Anisotropic electronic transport is a possible route towards nanoscale circuitry design, particularly in two-dimensional materials. Proposals to introduce such a feature in patterned graphene have to date relied on large-scale structural…

Mesoscale and Nanoscale Physics · Physics 2018-12-07 Soren Schou Gregersen , Jose H. Garcia , Antti-Pekka Jauho , Stephan Roche , Stephen R. Power

Periodic arrays of antidots, i.e. nanoscale perforations, in graphene enable tight confinement of carriers and efficient transport barriers. Such barriers evade the Klein tunneling mechanism by being of the mass rather than electrostatic…

Mesoscale and Nanoscale Physics · Physics 2013-06-11 Thomas Garm Pedersen , Jesper Goor Pedersen

We find clear signatures of spin-dependent negative differential resistance in compound systems comprising a graphene nanoribbon and a set of ferromagnetic insulator strips deposited on top of it. The periodic array of ferromagnetic strips…

Mesoscale and Nanoscale Physics · Physics 2013-10-21 J. Munárriz , C. Gaul , A. V. Malyshev , P. A. Orellana , C. A. Müller , F. Domínguez-Adame