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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

A population imbalance at different valleys of an electronic system lowers its effective rotational symmetry. We introduce a technique to measure such imbalance - a valley polarization - that exploits the unique fingerprints of this…

The band structure of transition metal dichalcogenides (TMDCs) with valence band edges at different locations in the momentum space could be harnessed to build devices that operate relying on the valley degree of freedom. To realize such…

Mesoscale and Nanoscale Physics · Physics 2016-09-06 Oriol Lopez Sanchez , Dmitry Ovchinnikov , Shikhar Misra , Adrien Allain , Andras Kis

Manipulating the valley degree of freedom to encode information for potential valleytronic devices has ignited a new direction in solid-state physics. A significant, fundamental challenge in the field of valleytronics is how to generate and…

Mesoscale and Nanoscale Physics · Physics 2020-07-02 Hui-Ying Mu , Yi-Tong Yao , Jie-Ru Li , Guo-Cai Liu , Chao He , Ying-Jie Sun , Guang Yang , Xing-Tao An , Yong-Zhe Zhang , Jian-Jun Liu

We theoretically demonstrate that 100\% valley-polarized transport in monolayers of MoS$_{2}$ and other group-VI dichalcogenides can be obtained using off-resonant circularly polarized light. By tuning the intensity of the off-resonant…

Mesoscale and Nanoscale Physics · Physics 2015-04-21 M. Tahir , A. Manchon , U. Schwingenschlogl

Two-dimensional materials that exhibit optically active spin and valley degrees of freedom represent one of the most fascinating -- and potentially most technologically useful -- platforms for the ultrafast interaction of light and matter.…

Mesoscale and Nanoscale Physics · Physics 2026-04-14 Ruikai Wu , Deepika Gill , Sangeeta Sharma , Sam Shallcross

Analogous to charge and spin, electrons in solids endows an additional degree of freedom: the valley pseudospin. Two-dimensional hexagonal materials such as graphene exhibit two valleys, labelled as $\mathbf{K}$ and $\mathbf{K}^{\prime}$.…

Mesoscale and Nanoscale Physics · Physics 2022-01-12 M. S. Mrudul , Gopal Dixit

Monolayer valley semiconductors, such as tungsten diselenide (WSe$_2$), possess valley pseudospin degrees of freedom that are optically addressable but degenerate in energy. Lifting the energy degeneracy by breaking time-reversal symmetry…

Strong spin-orbit coupling and inversion symmetry breaking in transition metal dichalcogenide monolayers yield the intriguing effects of valley-dependent optical selection rules. As such, it is possible to substantially polarize valley…

The selective control of specific momentum valleys lies at the core of valleytronics, a field that has thus far focused primarily on the $\mathbf{K}$ and $\mathbf{K'}$ valleys in transition metal dichalcogenides (TMDs). However, direct…

Strongly Correlated Electrons · Physics 2026-05-05 Youngjae Kim

Controlling the momentum of carriers in semiconductors, known as valley polarization, is a new resource for optoelectronics and information technologies. Materials exhibiting high polarization are needed for valley-based devices. Few-layer…

Mesoscale and Nanoscale Physics · Physics 2022-12-14 Rasmus H. Godiksen , Shaojun Wang , T. V. Raziman , Jaime Gómez Rivas , Alberto G. Curto

Some semiconductors have more than one degenerate minimum of the conduction band in their band structure. These minima-known as valleys-can be used for storing and processing information, if it is possible to generate a difference in their…

Mesoscale and Nanoscale Physics · Physics 2026-02-24 Adam Gindl , Martin Čmel , František Trojánek , Petr Malý , Martin Kozák

In solid, the crystalline structure can endow electron an internal degree of freedom known as valley, which characterizes the degenerate energy minima in momentum space. The recent success in optical pumping of valley polarization in 2D…

Mesoscale and Nanoscale Physics · Physics 2017-03-07 Xing-Tao An , Jiang Xiao , M. W. -Y. Tu , Hongyi Yu , Vladimir I. Fal'ko , Wang Yao

Producing currents predominantly from a single valley, namely valley-polarized currents, at optical-cycle timescales is an important aspect of the petahertz valleytronics, yet it remains less developed. This work exhibits the feasibility of…

Optics · Physics 2025-03-13 Wenqing Li , Xiaosong Zhu , Liang Li , Wanzhu He , Jie Long , Pengfei Lan , Peixiang Lu

The multiferroic materials, which coexist magnetism, ferroelectric, and ferrovalley, have broad practical application prospects in promoting the miniaturization and integration of spintronic and valleytronic devices. However, it is rare…

Materials Science · Physics 2025-02-26 Chao Wu , Hanbo Sun , Pengqiang Dong , Yin-Zhong Wu , Ping Li

Memory or transistor devices based on electron's spin rather than its charge degree of freedom offer certain distinct advantages and comprise a cornerstone of spintronics. Recent years have witnessed the emergence of a new field,…

Mesoscale and Nanoscale Physics · Physics 2021-09-13 Md. S. Hossain , M. K. Ma , K. A. Villegas Rosales , Y. J. Chung , L. N. Pfeiffer , K. W. West , K. W. Baldwin , M. Shayegan

In monolayers of semiconducting transition metal dichalcogenides, the light helicity ($\sigma^+$ or $\sigma^-$) is locked to the valley degree of freedom, leading to the possibility of optical initialization of distinct valley populations.…

Mesoscale and Nanoscale Physics · Physics 2016-05-25 T. Smoleński , M. Goryca , M. Koperski , C. Faugeras , T. Kazimierczuk , K. Nogajewski , P. Kossacki , M. Potemski

Ultrafast all-optical logic devices based on nonlinear light-matter interactions hold the promise to overcome the speed limitations of conventional electronic devices. Strong coupling of excitons and photons inside an optical resonator…

Valleytronics is one of the breaking-through to the technology of electronics, which provides a new degree of freedom to manipulate the properties of electrons. Combining DFT calculations, optical absorption analysis and the linear…

Materials Science · Physics 2017-08-16 Tiantian Zhang , Sijie Zhang , Gang Xu , Nanlin Wang , Zhong Fang

The robust spin and momentum valley locking of electrons in two-dimensional semiconductors make the valley degree of freedom of great utility for functional optoelectronic devices. Owing to the difference in optical selection rules for the…