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The achievement of valley-polarized electron currents is a cornerstone for the realization of valleytronic devices. Here, we report on ballistic coherent transport experiments where two opposite quantum point contacts (QPCs) are defined by…

We propose a device in which a sheet of graphene is coupled to a Weyl semimetal, allowing for the physical access to the study of tunneling from two-dimensional to three dimensional massless Dirac fermions. Due to the reconstructed band…

Mesoscale and Nanoscale Physics · Physics 2021-09-17 Ahmed Khalifa , Ribhu K. Kaul , Efrat Shimshoni , Herbert A. Fertig , Ganpathy Murthy

A novel type of photonic crystal formed by embedding a periodic array of constituent stacks of alternating graphene and dielectric discs into a background dielectric medium is proposed. The photonic band structure and transmittance of such…

Mesoscale and Nanoscale Physics · Physics 2010-12-21 Oleg L. Berman , Vladimir S. Boyko , Roman Ya. Kezerashvili , Anton A. Kolesnikov , Yurii E. Lozovik

We report on the possibility to simultaneously generate in graphene a {\it bulk valley-polarized dissipative transport} and a {\it quantum valley Hall effect} by combining strain-induced gauge fields and real magnetic fields. Such unique…

Mesoscale and Nanoscale Physics · Physics 2018-08-01 Mikkel Settnes , José Hugo García , Stephan Roche

The extensive research of two-dimensional layered materials has revealed that valleys, as energy extrema in momentum space, could offer a new degree of freedom for carrying information. Based on this concept, researchers have predicted…

Realizations of some topological phases in two-dimensional systems rely on the challenge of jointly incorporating spin-orbit and magnetic exchange interactions. Here, we predict the formation and control of a fully valley-polarized quantum…

Mesoscale and Nanoscale Physics · Physics 2021-10-25 Marc Vila , Jose H. Garcia , Stephan Roche

We investigate the electronic transport in graphene nanoelectromechanical resonators (GrNEMS), known also as graphene nanodrums or nanomembranes. We demonstrate that these devices, despite small values of out-of-plane strain, between $0.1$…

Mesoscale and Nanoscale Physics · Physics 2023-08-08 Walter Ortiz , Nikodem Szpak , Thomas Stegmann

Magic-angle twisted bilayer graphene displays a complex phase diagram as a function of flat band filling, featuring compressibility cascade transitions and a variety of competing ground states with broken spin, valley and point group…

Mesoscale and Nanoscale Physics · Physics 2026-01-29 Fernando Peñaranda , Héctor Ochoa , Fernando de Juan

A valley filter capable of generating a valley-polarized current is a crucial element in valleytronics, yet its implementation remains challenging. Here, we propose a valley filter made of a graphene bilayer which exhibits a 1D moir\'{e}…

Mesoscale and Nanoscale Physics · Physics 2024-04-19 Kai Shao , Hao Geng , Erfu Liu , Jose L. Lado , Wei Chen , D. Y. Xing

We theoretically study valley-filtering in pristine graphene irradiated by bicircular counter-rotating laser drive. The dynamical symmetry of the graphene and laser drive disrupts graphene's inversion symmetry, which results distinct…

Mesoscale and Nanoscale Physics · Physics 2024-01-23 Rekha Kumari , Gopal Dixit , Arijit Kundu

We study the effect of trigonal warping on the focussing of electrons by n-p junctions in graphene. We find that perfect focussing, which was predicted for massless Dirac fermions, is only preserved for one specific sample orientation. In…

Mesoscale and Nanoscale Physics · Physics 2017-07-25 K. J. A. Reijnders , M. I. Katsnelson

Valley degrees of freedom offer a potential resource for quantum information processing if they can be effectively controlled. We discuss an optical approach to this problem in which intense light breaks electronic symmetries of a…

Mesoscale and Nanoscale Physics · Physics 2016-01-11 Arijit Kundu , H. A. Fertig , Babak Seradjeh

We propose a scheme to trap and filter electrons, valley dependently, on a scale beyond the diffraction limit, in a gapped Dirac system using a circularly polarized light beam and a microscale metallic resonator. The main mechanism allowing…

Mesoscale and Nanoscale Physics · Physics 2019-01-23 Kevin Dini , Ivan V. Iorsh , Andrey Bogdanov , Ivan A. Shelykh

The ability to resolve the polarization of light with on-chip devices represents an urgent problem in optoelectronics. The detectors with polarization resolution demonstrated so far mostly require multiple oriented detectors or movable…

Mesoscale and Nanoscale Physics · Physics 2022-05-19 Valentin Semkin , Dmitry Mylnikov , Elena Titova , Sergey Zhukov , Dmitry Svintsov

For gapped graphene, we predict that an intense ultrashort (single-oscillation) circularly-polarized optical pulse can induce a large population of the conduction band and a large valley polarization. With an increase in the bandgap, the…

Mesoscale and Nanoscale Physics · Physics 2019-09-25 S. Azar Oliaei Motlagh , Fatemeh Nematollahi , Vadym Apalkov , Mark I. Stockman

Valley polarization (VP), an induced imbalance in the populations of a multi-valley electronic system, allows emission of second harmonic (SH) light even in centrosymmetric crystals such as graphene. Whereas in systems such as…

Mesoscale and Nanoscale Physics · Physics 2017-06-16 F. Hipolito , Vitor M. Pereira

Manipulating the circular polarization of light is of great importance in chemistry and biology, as chiral molecules exhibit different physiological properties when exposed to different circularly polarized waves. Here we suggest a…

Optics · Physics 2023-07-19 Tuo Chen , Sailing He

Junctions composed of two crossed graphene nanoribbons (GNRs) have been theoretically proposed as electron beam splitters where incoming electron waves in one GNR can be split coherently into propagating waves in \emph{two} outgoing…

Mesoscale and Nanoscale Physics · Physics 2022-07-13 Sofia Sanz , Nick Papior , Géza Giedke , Daniel Sánchez-Portal , Mads Brandbyge , Thomas Frederiksen

Graphene is a very promising test-bed for the field of electron quantum optics. However, a fully tunable and coherent electronic beam splitter is still missing. We report the demonstration of electronic beam splitters in graphene that…

Graphene on hBN (G/hBN) has a long period moir\'{e} superstructure owing to the lattice mismatch between two materials. Long periodic potential caused by the moir\'{e} superstructure induces modulation of electronic properties of the…

Mesoscale and Nanoscale Physics · Physics 2022-08-11 Keisuke Nakagahara , Katsunori Wakabayashi