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Valley magnetic moments play a crucial role in valleytronics in 2D hexagonal materials. Traditionally, based on studies of quantum states in homogeneous bulks, it is widely believed that only materials with broken structural inversion…

Mesoscale and Nanoscale Physics · Physics 2023-09-04 Zheng-Han Huang , Feng-Wu Chen , Yu-Shu G. Wu

We study the intervalley scattering in defected graphene by low-temperature transport measurements. The scattering rate is strongly suppressed when defects are charged. This finding highlights "screening" of the short-range part of a…

Mesoscale and Nanoscale Physics · Physics 2016-02-23 Baoming Yan , Qi Han , Zhenzhao Jia , Jingjing Niu , Tuocheng Cai , Dapeng Yu , Xiaosong Wu

The theoretical results are presented showing that strain-induced anisotropy of graphene spectrum gives rise to the valley currents under the illumination by normally incident light. The currents of the two graphene valleys are mutually…

Mesoscale and Nanoscale Physics · Physics 2014-08-13 T. L. Linnik

Particular strain geometry in graphene could leads to a uniform pseudo-magnetic field of order 10T and might open up interesting applications in graphene nano-electronics. Through quantum transport calculations of realistic strained…

Mesoscale and Nanoscale Physics · Physics 2015-03-13 Tony Low , F. Guinea

We report a comprehensive study of the two-phonon inter-valley (2D) Raman mode in graphene monolayers, motivated by recent reports of asymmetric 2D-mode lineshapes in freestanding graphene. For photon energies in the range $1.53 \rm eV -…

Mesoscale and Nanoscale Physics · Physics 2014-06-26 Stéphane Berciaud , Xianglong Li , Han Htoon , Louis E. Brus , Stephen K. Doorn , Tony F. Heinz

We show that the electron-phonon coupling in graphene, in contrast with the non-relativistic two-dimensional electron gas, leads to shifts in the phonon frequencies that are non-trivial functions of the electronic density. These shifts can…

Strongly Correlated Electrons · Physics 2013-05-29 A. H. Castro Neto , Francisco Guinea

Valley-dependent topological physics offers a promising avenue for designing nanoscale devices based on gapless single-layer graphene. To demonstrate this potential, we investigate an electrical bias-controlled topological discontinuity in…

Mesoscale and Nanoscale Physics · Physics 2026-01-26 Zheng-Han Huang , Jing-Yuan Lai , Yu-Shu G. Wu

The dynamic polarization for kekul\'e-patterned graphene is studied within the Random Phase Approximation (RPA). It is shown how the breaking of the valley degeneracy by the lattice modulation is manifested through the dielectric spectrum,…

Mesoscale and Nanoscale Physics · Physics 2020-12-03 Saúl A. Herrera , Gerardo G. Naumis

Electrons in graphene have fourfold spin and valley degeneracies owing to the unique bipartite honeycomb lattice and an extremely weak spin-orbit coupling, which can support a series of broken symmetry states. Atomic-scale defects in…

Mesoscale and Nanoscale Physics · Physics 2022-08-17 Yu Zhang , Liangguang Jia , Yaoyao Chen , Lin He , Yeliang Wang

It is quite easy to control spin polarization and spin direction of a system via magnetic fields. However, there is no such a direct and efficient way to manipulate valley pseudospin degree of freedom. Here, we demonstrate experimentally…

Mesoscale and Nanoscale Physics · Physics 2020-03-18 Si-Yu Li , Ying Su , Ya-Ning Ren , Lin He

Graphene corrugations affect hybridization of $\pi$ and $\sigma$ orbitals of carbon atoms in graphene based systems. It can as well break differently the symmetry of the electron transfer integrals for different strip boundaries. Using…

Mesoscale and Nanoscale Physics · Physics 2024-05-07 M. Pudlak , R. G. Nazmitdinov

Valley-polarized currents can be generated by local straining of multi-terminal graphene devices. The pseudo-magnetic field created by the deformation allows electrons from only one valley to transmit and a current of electrons from a…

Mesoscale and Nanoscale Physics · Physics 2016-11-18 S. P. Milovanovic , F. M. Peeters

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

By analytically constructing the matrix elements of an electron-phonon interaction for the $D$ band in the Raman spectra of armchair graphene nanoribbons, we show that pseudospin and momentum conservation result in (i) a $D$ band consisting…

Mesoscale and Nanoscale Physics · Physics 2012-03-14 K. Sasaki , K. Kato , Y. Tokura , S. Suzuki , T. Sogawa

Valley polarization in graphene breaks inversion symmetry and therefore leads to second-harmonic generation. We present a complete theory of this effect within a single-particle approximation. It is shown that this may be a sensitive tool…

Mesoscale and Nanoscale Physics · Physics 2015-06-22 T. O. Wehling , A. Huber , A. I. Lichtenstein , M. I. Katsnelson

It is known that the lowest propagating mode in a narrow ballistic ribbon of graphene may lack the twofold valley degeneracy of higher modes. Depending on the crystallographic orientation of the ribbon axis, the lowest mode mixes both…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 A. Rycerz , J. Tworzydlo , C. W. J. Beenakker

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

Graphene's outstanding mechanical properties lend to strain engineering, allowing for future valleytronics and nanoelectromechanic applications. In this work, we have found that a Gaussian-shaped strain on a graphene p-n junction results in…

Mesoscale and Nanoscale Physics · Physics 2019-07-23 Nojoon Myoung , Hyungkook Choi , Hee Chul Park

At the 2D limit, hexagonal systems such as monolayer transition metal dichalcogenides (TMDs) and graphene exhibit unique coupled spin and momentum-valley physics (valley pseudospin) owing to broken spatial inversion symmetry and strong…

Materials Science · Physics 2023-06-21 Tristan L Britt , Bradley J. Siwick

The existence of two-inequivalent valleys in the band structure of graphene has motivated the search of mechanisms that allow their separation and control for potential device applications. Among the several schemes proposed in the…

Mesoscale and Nanoscale Physics · Physics 2018-10-31 Dawei Zhai , Nancy Sandler