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Structured light beams with space-variant polarization can be efficiently generated using voltage-tunable nematic liquid-crystal (Q-plate). By appropriately selecting the input state and the retardation of the Q-plate, an optical field…

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 demonstrate a pump-probe scheme in which an atomic vapor is optically pumped with circularly polarized light and probed with a vector vortex beam. The pump induces a macroscopic magnetization in the medium, which gives rise to…

Understanding the origin of splitting of valance band is important since it governs the unique spin and valley physics in few-layer MoS2. With first principle methods, we explore the effects of spin-orbit coupling and layer's coupling on…

Materials Science · Physics 2015-09-22 Xiaofeng Fan , W. T. Zheng , David J. Singh

Local energy extrema of the bands in momentum space, or valleys, can endow electrons in solids with pseudo-spin in addition to real spin. In transition metal dichalcogenides this valley pseudo-spin, like real spin, is associated with a…

Mesoscale and Nanoscale Physics · Physics 2015-06-22 Grant Aivazian , Zhirui Gong , Aaron M Jones , Rui-Lin Chu , Jiaqiang Yan , David G Mandrus , Chuanwei Zhang , David Cobden , Wang Yao , Xiaodong Xu

Monolayer transition metal dichalcogenides have emerged as prominent candidates to explore the complex interplay between the spin and the valleys degrees of freedom. The strong spin-orbit interaction and broken inversion symmetry within…

MoS2 is a highly interesting material system, which exhibits a crossover from an indirect band gap in the bulk crystal to a direct gap for single layers. Here, we perform a direct comparison between large-area MoS$_2$ films grown by…

Materials Science · Physics 2014-05-28 G. Plechinger , J. Mann , E. Preciado , D. Barroso , A. Nguyen , J. Eroms , C. Schüller , L. Bartels , T. Korn

Two-dimensional (2D) transition metal dichalcogenides (TMDs), especially MoS2 and WS2 recently attract extensive attentions due to their rich physics and great potential applications. Superior to graphene, MS2 (M = Mo/W) monolayers have a…

Materials Science · Physics 2013-12-06 Chunxiao Cong , Jingzhi Shang , Xing Wu , Bingchen Cao , Namphung Peimyoo , Caiyu Qiu , Litao Sun , Ting Yu

Optical pumping of excited exciton states in semiconductor quantum wells is a tool for realisation of ultra-compact terahertz (THz) lasers based on stimulated optical transition between excited (2p) and ground (1s) exciton state. We show…

Mesoscale and Nanoscale Physics · Physics 2013-01-30 G. Slavcheva , A. V. Kavokin

Electrons in certain two-dimensional crystals possess a pseudospin degree of freedom associated with the existence of two inequivalent valleys in the Brillouin zone. If, as in monolayer MoS2, inversion symmetry is broken and time-reversal…

Disordered Systems and Neural Networks · Physics 2015-09-28 Thomas Olsen , Ivo Souza

Air lasing provides a promising technique to remotely produce coherent radiation in the atmosphere and attracts continuous attention. However, the polarization properties of N2+ lasing with seeding has not been understood since it was…

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

Two-dimensional (2D) compounds provide unique building blocks for novel layered devices and hybrid photonic structures. However, large surface-to-volume ratio in thin films enhances the significance of surface interactions and charging…

Photon splitting due to vacuum polarization in a laser field is considered. Using an operator technique, we derive the amplitudes for arbitrary strength, spectral content and polarization of the laser field. The case of a monochromatic…

High Energy Physics - Phenomenology · Physics 2007-09-08 A. Di Piazza , A. I. Milstein , C. H. Keitel

We investigate the valley depolarization due to the electron-hole exchange interaction in monolayer MoS$_{2}$. Both the long- and short-range parts of the intra- and inter-valley electron-hole exchange interactions are calculated. We find…

Mesoscale and Nanoscale Physics · Physics 2014-05-13 T. Yu , M. W. Wu

In this letter we report on the synthesis of monolayers of MoS$_2$ via chemical vapor deposition directly on thin films of Al$_2$O$_3$ grown by spatial atomic layer deposition. The synthesized monolayers are characterized by atomic force…

We theoretically study the ultrafast optical control of multiple valley states in two-dimensional (2D) tin sulfide (SnS) monolayers, a member of the layered group-IV monochalcogenides, which is a promising class of materials for overcoming…

We investigate the nonequilibrium topological phases of monolayer 1T$^\prime$--MoS$_2$ under high-frequency circularly polarized driving using a low-energy $k\!\cdot\!p$ Hamiltonian combined with a van Vleck expansion. The off-resonant…

Mesoscale and Nanoscale Physics · Physics 2025-11-20 Mohammad Mortezaei Nobahari

Using temperature dependent photoluminescence (PL), polarization resolved PL and Raman spectroscopy, we investigate the effect of in situ vacuum annealing as well as the relaxation of strain on the luminescence and the valley polarization…

Materials Science · Physics 2022-12-09 Poulab Chakrabarti , Faiha Mujeeb , Subhabrata Dhar

Valley, as a new degree of freedom for electrons, has drawn considerable attention due to its significant potential for encoding and storing information. Lifting the energy degeneracy to achieve valley polarization is necessary for…

Materials Science · Physics 2020-03-11 Pei Zhaos , Yandong Ma , Hao Wang , Baibiao Huang , Liangzhi Kou , Ying Dai