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Chiral interaction between light and two-dimensional transition metal dichalcogenides (2D-TMDs) has recently drawn enormous scientific attention. The optical selection rules of these atomically thin semiconductors allow the attribution of a…

Optics · Physics 2021-06-08 Irina Komen , Sabrya E. van Heijst , Sonia Conesa-Boj , L. Kuipers

Two-dimensional magnetism and valleys have recently emerged as two significant research areas, with intriguing properties and practical uses in advanced information technology. Considering the importance of these two areas and their…

Materials Science · Physics 2023-09-06 Xiaoyu Wang , Li Liang , Huiqian Wang , Xiao Li

We investigate the chirality of phonon modes in twisted bilayer WSe2 and demonstrate distinct chiral behavior of the $K/K^\prime$ valley phonons for twist angles close to $0^{\circ}$ and close to $60^{\circ}$. In particular, multiple chiral…

Materials Science · Physics 2022-01-26 Indrajit Maity , Arash A. Mostofi , Johannes Lischner

We study the electronic structures and topological properties of $(M+N)$-layer twisted graphene systems. We consider the generic situation that $N$-layer graphene is placed on top of the other $M$-layer graphene, and is twisted with respect…

Mesoscale and Nanoscale Physics · Physics 2019-08-14 Jianpeng Liu , Zhen Ma , Jinhua Gao , Xi Dai

Monolayer transition-metal dichalcogenides (TMDCs) have recently emerged as possible candidates for valleytronic applications, as the spin and valley pseudospin are directly coupled and stabilized by a large spin splitting. In these…

The phonon magnetochiral effect consists of a nonreciprocity in the velocity or attenuation of acoustic waves when they propagate parallel and antiparallel to an external magnetic field. The first experimental observation of this effect has…

Mesoscale and Nanoscale Physics · Physics 2020-10-07 Sanghita Sengupta , M. Nabil Y. Lhachemi , Ion Garate

The notion that phonons can carry pseudo-angular momentum has become popular in the last decade, with recent research efforts highlighting phonon chirality, Berry curvature of phonon band structure, and the phonon Hall effect. When a phonon…

The altermagnetism caused by alternating crystal environment provides a unique opportunity for designing new type of valley polarization. Here, we propose a way to realize valley polarization in two-dimensional (2D) tetragonal…

Mesoscale and Nanoscale Physics · Physics 2024-09-24 San-Dong Guo Xiao-Shu Guo , Guangzhao Wang

To date, a number of valley materials have been discovered with the spin-valley or valley-layer couplings. It is highly desirable to realize the interplay of more electronic degrees of freedom in a valley material. Based on the…

Materials Science · Physics 2023-05-24 Xiaohui Wang , Li Liang , Xiao Li

Valley Hall effect has been observed in asymmetric single-layer and bilayer graphene systems. In single-layer graphene systems, asymmetry is introduced by aligning graphene with hexagonal boron nitride (hBN) with a near-zero twist angle,…

Mesoscale and Nanoscale Physics · Physics 2023-11-16 Teppei Shintaku , Afsal Kareekunnan , Masashi Akabori , Kenji Watanabe , Takashi Taniguchi , Hiroshi Mizuta

In monolayer transition metal dichalcogenides, tightly bound excitons have been discovered with a valley pseudospin that can be optically addressed through polarization selection rules. Here, we show that this valley pseudospin is strongly…

Mesoscale and Nanoscale Physics · Physics 2014-05-20 Hongyi Yu , Guibin Liu , Pu Gong , Xiaodong Xu , Wang Yao

Using the density functional theory calculations, we predict that several monolayer chromium-based materials exhibit a triple-Q tetrahedral magnetic insulating ground state. By studying the effect of biaxial strain on monolayer…

Materials Science · Physics 2025-05-06 Xiu-Cai Jiang , Li-Ya Qiao , Yu-Zhong Zhang

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

Using the valley degree of freedom as a carrier of information for storage and processing, valley polarization plays a crucial role. A variety of mechanisms for valley polarization have been proposed, among which the valley-layer coupling…

Materials Science · Physics 2025-05-29 San-Dong Guo , Liguo Zhang , Xiao-Shu Guo , Gangqiang Zhu

Two-dimensional semiconductors feature valleytronics phenomena due to locking of the spin and momentum valley of the electrons. However, the valley polarization is intrinsically limited in monolayer crystals by the fast intervalley…

Mesoscale and Nanoscale Physics · Physics 2019-07-10 Long Zhang , Rahul Gogna , G. William Burg , Jason Horng , Eunice Paik , Yu-Hsun Chou , Kyounghwan Kim , Emanuel Tutuc , Hui Deng

Monolayer (1L) transition metal dichalcogenides (TMDCs) are attractive materials for several optoelectronic applications because of their strong excitonic resonances and valley-selective response. Valley excitons in 1L-TMDCs are formed at…

Optics · Physics 2018-05-30 Alex Krasnok , Andrea Alu

Lattice vibrations carrying angular momentum, known as chiral phonons, have emerged as a promising route to control and understand complex material properties, yet their deterministic manipulation remains largely unexplored. Here we…

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.…

Electrons in monolayer transition metal dichalcogenides (TMDs) possess both the valley and spin degree of freedom. These internal quantum degrees of freedom have provided an ideal laboratory for exploring both new physical phenomena and…

Mesoscale and Nanoscale Physics · Physics 2017-02-21 Zefang Wang , Jie Shan , kin Fai Mak

We study the hybrid excitations due to the coupling between surface optical phonons of a polar insulator substrate and plasmons in the valley-spin-polarized metal phase of silicene under an exchange field. We perform the calculations within…

Mesoscale and Nanoscale Physics · Physics 2018-11-30 M. Mirzaei , T. Vazifehshenas , T. Salavati-fard , M. Farmanbar , B. Tanatar