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Valley currents and non-local resistances of graphene nanostructures with broken inversion symmetry are considered theoretically in the linear response regime. Scattering state wave functions of electrons entering the nanostructure from the…

Mesoscale and Nanoscale Physics · Physics 2015-09-24 George Kirczenow

The anomalous Hall effect in time-reversal symmetry broken systems is underpinned by the concept of Berry curvature in band theory. However, recent experiments reveal that the nonlinear Hall effect can be observed in non-magnetic systems…

Mesoscale and Nanoscale Physics · Physics 2023-08-22 Arka Bandyopadhyay , Nesta Benno Joseph , Awadhesh Narayan

We propose a spectroscopic method of identifying broken symmetry states of bilayer graphene. We demonstrate theoretically that, in contrast to gapped states, a strained bilayer crystal or nematic phase of the electronic liquid are…

Mesoscale and Nanoscale Physics · Physics 2012-11-01 D. S. L. Abergel , Vladimir I. Fal'ko

Valleytronics, which makes use of the two valleys in graphenes, attracts considerable attention and a valley filter is expected to be the central component in valleytronics. We propose the application of the graphene valley filter using…

Mesoscale and Nanoscale Physics · Physics 2023-08-15 Mitsuharu Uemoto , Masaki Nishiura , Tomoya Ono

The valley Hall effect arises from valley contrasting Berry curvature and requires inversion symmetry breaking. Here, we propose a nonlinear mechanism to generate a valley Hall current in systems with both inversion and time-reversal…

Mesoscale and Nanoscale Physics · Physics 2025-01-28 Kamal Das , Koushik Ghorai , Dimitrie Culcer , Amit Agarwal

We study spatial symmetry in general ABA-stacked multilayer graphene to illustrate how electronic spectra at the two valleys are related in a magnetic field. We show that the lattice of multilayers with an even number of layers, as well as…

Mesoscale and Nanoscale Physics · Physics 2015-05-14 Mikito Koshino , Edward McCann

We show that inversion symmetry breaking together with spin-orbit coupling leads to coupled spin and valley physics in monolayers of MoS2 and other group-VI dichalcogenides, making possible controls of spin and valley in these 2D materials.…

Mesoscale and Nanoscale Physics · Physics 2012-05-09 Di Xiao , Gui-Bin Liu , Wanxiang Feng , Xiaodong Xu , Wang Yao

We investigate the electronic dispersion and transport properties of graphene/WSe$_{2}$ heterostructures in the presence of a proximity-induced spin-orbit coupling $\lambda_{v}$, sublattice potential $\Delta$, and an off-resonant circularly…

Mesoscale and Nanoscale Physics · Physics 2023-07-07 M. Zubair , P. Vasilopoulos , M. Tahir

Achieving a population imbalance between the two inequivalent valleys is a critical first step for any valleytronic device. A valley-polarization can be induced in biased bilayer graphene using circularly polarized light. In this paper, we…

Mesoscale and Nanoscale Physics · Physics 2021-02-17 Alex Friedlan , Marc M. Dignam

In this paper, we study valley degree of freedom in all dielectric silicon photonic graphene. Photonic band gap opening physics under inversion symmetry breaking is revisited by the viewpoint of nonzero valley Chern number. Bulk valley…

Optics · Physics 2019-06-18 Xiao-Dong Chen , Jian-Wen Dong

In this letter we demonstrate universal symmetry breaking by means of magnetically induced circular dichroism. Magnetic field induces forbidden at zero field atomic transitions between $\Delta F = \pm2$ hyperfine levels. In a particular…

Atomic Physics · Physics 2017-08-31 A. Tonoyan , A. Sargsyan , E. Klinger , G. Hakhumyan , C. Leroy , M. Auzinsh , A. Papoyan , D. Sarkisyan

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

In transition metal dichalcogenides, the valley degree of freedom directly couples valley-polarised excitons - excited by circularly polarised light - to valley-dependent chiral photons, enabling ultrafast light-driven valleytronics.…

Symmetry breaking in two-dimensional layered materials plays a significant role in their macroscopic electrical, optical, magnetic and topological properties, including but not limited to spin-polarization effects, valley-contrasting…

Mesoscale and Nanoscale Physics · Physics 2021-03-09 Luojun Du , Tawfique Hasan , Andres Castellanos-Gomez , Gui-Bin Liu , Yugui Yao , Chun Ning Lau , Zhipei Sun

Photonics and optoelectronics are at the foundations of widespread technologies, from high-speed Internet to systems for artificial intelligence, automotive LiDAR, and optical quantum computing. Light enables ultrafast speeds and low energy…

Optics · Physics 2021-06-30 Alex Krasnok , Andrea Alú

Berry curvature is analogous to magnetic field but in momentum space and is commonly present in materials with non-trivial quantum geometry. It endows Bloch electrons with transverse anomalous velocities to produce Hall-like currents even…

Valley pseudospin, the quantum degree of freedom characterizing the degenerate valleys in energy bands, is a distinct feature of two-dimensional Dirac materials. Similar to spin, the valley pseudospin is spanned by a time reversal pair of…

Mesoscale and Nanoscale Physics · Physics 2016-01-20 Mengqiao Sui , Guorui Chen , Liguo Ma , Wenyu Shan , Dai Tian , Kenji Watanabe , Takashi Taniguchi , Xiaofeng Jin , Wang Yao , Di Xiao , Yuanbo Zhang

Two-dimensional (2D) noncentrosymmetric systems offer potential opportunities for exploiting the valley degrees of freedom for advanced information processing, owing to non-zero Berry curvature. However, such valley polarization in 2D…

Materials Science · Physics 2023-10-10 Souren Adhikary , Sudipta Dutta

Physical properties reflecting valley asymmetry of Landau levels in a biased bilayer graphene under magnetic field are discussed. Within the $4-$band continuum model with Hartree-corrected self-consistent gap and finite damping factor we…

Mesoscale and Nanoscale Physics · Physics 2010-01-14 Masaaki Nakamura , Eduardo V. Castro , Balazs Dora

Three symmetries prevent a twisted bilayer of graphene from developing an in-plane spontaneous magnetization in the absence of a magnetic field - time reversal symmetry, $C_2$ symmetry to $\pi$ rotation and $C_3$ symmetry to $2\pi/3$…

Strongly Correlated Electrons · Physics 2022-04-06 Ohad Antebi , Ady Stern , Erez Berg