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We investigate disorder effects on Landau levels in Dirac electron systems with the use of a non-Hermitian quasiparticle Hamiltonian formalism. This formalism reveals that spin-dependent scattering rates induce the spectrum collapse of…

Mesoscale and Nanoscale Physics · Physics 2021-06-07 Taiki Matsushita , Yuki Nagai , Satoshi Fujimoto

We investigate the fine structure in the energy spectrum of bilayer graphene in the presence of various stacking defaults, such as a translational or rotational mismatch. This fine structure consists of four Dirac points that move away from…

Mesoscale and Nanoscale Physics · Physics 2013-10-22 R. de Gail , M. O. Goerbig , G. Montambaux

We investigate the spin-dependent transport properties of a ferromagnetic/strained/normal graphene junctions with central region subjected to a magnetic field $B$. An analytical approach, based on Dirac equation, is implemented to obtain…

Mesoscale and Nanoscale Physics · Physics 2019-09-04 Youness Zahidi , Ilham Redouani , Ahmed Jellal , Hocine Bahlouli

A single graphene layer exhibits an anomalous Landau level spectrum. A massless Dirac like low energy electronic spectrum underlies this anomaly. We study, analytically and numerically, the effect of a uniform electric field $(E)$ on the…

Mesoscale and Nanoscale Physics · Physics 2007-07-07 Vinu Lukose , R. Shankar , G. Baskaran

Bilayer graphene under a magnetic field has an octet of quasidegenerate levels due to spin, valley, and orbital degeneracies. This zero-energy Landau level is resolved into several incompressible states whose nature is still elusive. We use…

Strongly Correlated Electrons · Physics 2016-12-28 Angelika Knothe , Thierry Jolicoeur

We review the energy spectrum and transport properties of several types of one- dimensional superlattices (SLs) on single-layer and bilayer graphene. In single-layer graphene, for certain SL parameters an electron beam incident on a SL is…

Mesoscale and Nanoscale Physics · Physics 2015-03-17 M. Barbier , P. Vasilopoulos , F. M. Peeters

We obtain analytical expressions for the eigenstates and the Landau level spectrum of biased graphene bilayers in a magnetic field. The calculations are performed in the context of a four-band continuum model and generalize previous…

Mesoscale and Nanoscale Physics · Physics 2007-08-08 J. Milton Pereira , F. M. Peeters , P. Vasilopoulos

We consider the problem of multilayer graphene on a Haldane sphere and determine the Landau level spectrum for this family of systems. This serves as a generalization of the Landau quantization problem of ordinary non-relativistic Haldane…

Mesoscale and Nanoscale Physics · Physics 2020-05-04 Wei-Han Hsiao

We consider graphene in the presence of external magnetic field and elastic deformations that cause emergent magnetic field. The total magnetic field results in the appearance of Landau levels in the spectrum of quasiparticles. In addition,…

Mesoscale and Nanoscale Physics · Physics 2016-10-04 Z. V. Khaidukov , M. A. Zubkov

The large lattice constant of Moire superlattice formed in twisted bilayer graphene for small twist enables observing the Landau levels splitting into Hofstadter butterflies in energy spectra for moderate magnetic field. This is expected…

Mesoscale and Nanoscale Physics · Physics 2021-04-22 Tomasz Chwiej

Dirac electrons in finite graphene samples with zigzag edges under high magnetic fields (in the regime of Landau-level formation) are investigated with regard to their bulk-type and edge-type character. We employ tight-binding calculations…

Mesoscale and Nanoscale Physics · Physics 2011-02-16 Igor Romanovsky , Constantine Yannouleas , Uzi Landman

When electrons are confined in a two dimensional (2D) system, typical quantum mechanical phenomena such as Landau quantization can be detected. Graphene systems, including the single atomic layer and few-layer stacked crystals, are ideal 2D…

Mesoscale and Nanoscale Physics · Physics 2017-03-14 Long-jing Yin , Ke-ke Bai , Wen-xiao Wang , Si-Yu Li , Yu Zhang , Lin He

We consider massless Dirac fermions in a graphene monolayer subject to both a perpendicular magnetic field $B$ and a proximity-induced pairing gap $\Delta$. When the chemical potential is at the Dirac point, our exact solution of the…

Mesoscale and Nanoscale Physics · Physics 2017-10-30 L. Cohnitz , A. De Martino , W. Häusler , R. Egger

If bilayer graphene is placed in a high perpendicular magnetic field, several quantum Hall plateaus are observed at low enough temperatures. Of these, the $\sigma_{xy}=4ne^2/h$ sequence ($n\neq0$) is explained by standard Landau…

Mesoscale and Nanoscale Physics · Physics 2013-05-30 Judit Sari , Csaba Toke

We investigate electronic transport in high mobility (\textgreater 100,000 cm$^2$/V$\cdot$s) trilayer graphene devices on hexagonal boron nitride, which enables the observation of Shubnikov-de Haas oscillations and an unconventional quantum…

Mesoscale and Nanoscale Physics · Physics 2011-08-02 Thiti Taychatanapat , Kenji Watanabe , Takashi Taniguchi , Pablo Jarillo-Herrero

In the presence of strong magnetic fields the electronic bandstructure of graphene drastically changes. The Dirac cone collapses into discrete non-equidistant Landau levels, which can be externally tuned by changing the magnetic field. In…

Mesoscale and Nanoscale Physics · Physics 2017-07-26 Samuel Brem , Florian Wendler , Ermin Malic

We investigate the emergence of extra Dirac points in the electronic structure of a periodically spaced barrier system, i.e., a superlattice, on single-layer graphene, using a Dirac-type Hamiltonian. Using square barriers allows us to find…

Mesoscale and Nanoscale Physics · Physics 2015-05-18 M. Barbier , P. Vasilopoulos , F. M. Peeters

We show through both theoretical arguments and numerical calculations that graphene discerns an unconventional sequence of quantized Hall conductivity, when subject to both magnetic fields (B) and strain. The latter produces time-reversal…

Mesoscale and Nanoscale Physics · Physics 2015-03-20 Bitan Roy , Zi-Xiang Hu , Kun Yang

Intricate interplay between the periodicity of the lattice structure and that of the cyclotron motion gives rise to a well-known self-similar fractal structure of the energy eigenvalue, known as the Hofstadter butterfly, for an electron…

Mesoscale and Nanoscale Physics · Physics 2013-02-08 Jun-Won Rhim , Kwon Park

Magnetotransport measurements are performed in ultraclean (lithographically patterned) graphene nanoribbons down to 70 nm. At high magnetic fields, a fragmentation of the electronic spectrum into a Landau levels pattern with unusual…