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We introduce a two-dimensional model of spin-1/2 Dirac fermions in graphene subjected to a highly tunable electric field, which exhibits super-Klein tunneling. The electric field can be continuously interpolated between two limiting…

Mesoscale and Nanoscale Physics · Physics 2026-03-24 Alonso Contreras-Astorga , Francisco Correa , Luis Inzunza , Vit Jakubsky , Raul Valencia-Torres

We show that a graphene pnp junction with a central superconducting electrode acts as a Veselago lens for incoming electrons by focusing them and their phase-conjugated counterpart (holes) into different points of the optical axis. This…

Mesoscale and Nanoscale Physics · Physics 2012-04-11 S. Gomez , P. Burset , W. J. Herrera , A. Levy Yeyati

Next generation hard X-ray free electron lasers require electron beams with low transverse emittance. One proposal to achieve these low emittances is to exploit the eigen-emittance values of the beam. The eigen-emittances are invariant…

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

In this Letter, both the manipulation of valley-polarized currents and the optical-like behaviors of Dirac fermions are theoretically explored in polycrystalline graphene. When strain is applied, the misorientation between two graphene…

Mesoscale and Nanoscale Physics · Physics 2016-12-14 Viet Hung Nguyen , Samuel Dechamps , Philippe Dollfus , Jean-Christophe Charlier

The properties of Dirac electrons in a magnetic superlattice (SL) on graphene consisting of very high and thin (delta-function) barriers are investigated. We obtain the energy spectrum analytically and study the transmission through a…

Mesoscale and Nanoscale Physics · Physics 2015-05-13 M. Ramezani Masir , P. Vasilopoulos , F. M. Peeters

Focusing of electron waves in graphene p-n junctions is a striking manifestation of fermionic negative refraction. We analyze lensing in smooth p-n junctions and find that it differs in several interesting ways from that in the previously…

Mesoscale and Nanoscale Physics · Physics 2016-10-04 Vo Tien Phong , Jian Feng Kong

The hybridization of $\sigma$ and $\pi$ orbitals of carbon atoms in graphene depends on the surface curvature. Considering a single junction between flat and rippled graphene subsystems, it is found an accumulation of charge in the rippled…

Mesoscale and Nanoscale Physics · Physics 2019-11-19 M. Pudlak , R. G. Nazmitdinov

The unconventional properties of graphene, with a massless Dirac band dispersion and large coherence properties, have raised a large interest for applications in nanoelectronics. In this work, we emphasize that graphene two dimensional…

Mesoscale and Nanoscale Physics · Physics 2008-08-27 Pierre Darancet , Valerio Olevano , Didier Mayou

We show that surface plasmons of a two-dimensional Dirac metal such as graphene can be reflected by line-like perturbations hosting one-dimensional electron states. The reflection originates from a strong enhancement of the local optical…

Mesoscale and Nanoscale Physics · Physics 2016-08-24 Bor-Yuan Jiang , Guangxin Ni , Cheng Pan , Zhe Fei , Bin Cheng , Chun Ning Lau , Marc Bockrath , Dimitri N. Basov , Michael M. Fogler

The relativistic charge carriers in monolayer graphene can be manipulated in manners akin to conventional optics (electron-optics): angle-dependent Klein tunneling collimates an electron beam (analogous to a laser), while a Veselago…

Mesoscale and Nanoscale Physics · Physics 2022-11-23 Xi Zhang* , Wei Ren* , Elliot Bell , Ziyan Zhu , Kenji Watanabe , Takashi Taniguchi , Efthimios Kaxiras , Mitchell Luskin , Ke Wang

Transport through potential barriers in graphene is investigated using a set of metallic gates capacitively coupled to graphene to modulate the potential landscape. When a gate-induced potential step is steep enough, disorder becomes less…

Mesoscale and Nanoscale Physics · Physics 2009-01-18 N. Stander , B. Huard , D. Goldhaber-Gordon

High-mobility graphene hosting massless charge carriers with linear dispersion provides a promising platform for electron optics phenomena. Inspired by the physics of dielectric optical micro-cavities where the photon emission…

Mesoscale and Nanoscale Physics · Physics 2022-12-15 Jule-Katharina Schrepfer , Szu-Chao Chen , Ming-Hao Liu , Klaus Richter , Martina Hentschel

We study electronic transport in graphene/ferromagnetic insulator hybrid devices. The system comprises an armchair graphene nanoribbon with a lens-shaped EuO ferromagnetic insulator layer deposited on top of it. When the device supports a…

Mesoscale and Nanoscale Physics · Physics 2021-02-12 Yuriko Baba , Marta Saiz-Bretín

The relativistic nature of charge carriers in graphene is expected to lead to an angle- dependent transmission through a potential barrier, where Klein tunneling involves annihilation of an electron and a hole at the edges of the barrier.…

Mesoscale and Nanoscale Physics · Physics 2014-01-29 Atikur Rahman , Janice Wynn Guikema , N. M. Hassan , Nina Markovic

Compact acceleration of a tightly collimated relativistic electron beam with high charge from a laser-plasma interaction has many unique applications. However, currently the well-known schemes, including laser wakefield acceleration from…

Graphene placed in a magnetic field possesses an extremely high mid/far-infrared optical nonlinearity originating from its unusual band structure and selection rules for the optical transitions near the Dirac point. Here we study the linear…

Mesoscale and Nanoscale Physics · Physics 2016-11-26 Xianghan Yao , Alexey Belyanin

Graphene has exceptional optical, mechanical and electrical properties, making it an emerging material for novel optoelectronics, photonics and for flexible transparent electrode applications. However, the relatively high sheet resistance…

Mesoscale and Nanoscale Physics · Physics 2013-02-06 Guang-Xin Ni , Yi Zheng , Sukang Bae , Chin Yaw Tan , Orhan Kahya , Jing Wu , Byung Hee Hong , Kui Yao , Barbaros Özyilmaz

We study theoretically nonlinear propagation of light in a graphene monolayer. We show that the large intrinsic nonlinearity of graphene at optical frequencies enables the formation of quasi one-dimensional self-guided beams (spatial…

Quantum confinement of graphene Dirac-like electrons in artificially crafted nanometer structures is a long sought goal that would provide a strategy to selectively tune the electronic properties of graphene, including bandgap opening or…