title: Ultrafast multi-level logic gates with spin-valley coupled polarization anisotropy in monolayer MoS2.
abstract: The inherent valley-contrasting optical selection rules for interband transitions at the K and K' valleys in monolayer MoS2 have attracted extensive interest. Carriers in these two valleys can be selectively excited by circularly polarized optical fields. The comprehensive dynamics of spin valley coupled polarization and polarized exciton are completely resolved in this work. Here, we present a systematic study of the ultrafast dynamics of monolayer MoS2 including spin randomization, exciton dissociation, free carrier relaxation, and electron-hole recombination by helicity- and photon energy-resolved transient spectroscopy. The time constants for these processes are 60 fs, 1 ps, 25 ps, and ~300 ps, respectively. The ultrafast dynamics of spin polarization, valley population, and exciton dissociation provides the desired information about the mechanism of radiationless transitions in various applications of 2D transition metal dichalcogenides. For example, spin valley coupled polarization provides a promising way to build optically selective-driven ultrafast valleytronics at room temperature. Therefore, a full understanding of the ultrafast dynamics in MoS2 is expected to provide important fundamental and technological perspectives.
authors: Department of Electrophysics, National Chiao Tung University, Hsinchu, Taiwan.
authors: Yu-Ting
authors: YT
authors: Wang
authors: 1] Department of Electrophysics, National Chiao Tung University, Hsinchu, Taiwan [2] Taiwan Consortium of Emergent Crystalline Materials, Ministry of Science and Technology, Taipei 10601, Taiwan.
authors: Chih-Wei
authors: CW
authors: Luo
authors: Department of Electrophysics, National Chiao Tung University, Hsinchu, Taiwan.
authors: Atsushi
authors: A
authors: Yabushita
authors: Department of Electrophysics, National Chiao Tung University, Hsinchu, Taiwan.
authors: Kaung-Hsiung
authors: KH
authors: Wu
authors: 1] Department of Electrophysics, National Chiao Tung University, Hsinchu, Taiwan [2] Advanced Ultrafast Laser Research Center and Department of Engineering Science, The University of Electro-Communications, Chofu, Tokyo 182-8585, Japan [3] JST, CREST, 5 Sanbancho, Chiyoda-Ku, Tokyo 102-0075, Japan.
authors: Takayoshi
authors: T
authors: Kobayashi
authors: Center for Micro/Nano Science and Technology, National Cheng Kung University, Tainan, Taiwan.
authors: Chang-Hsiao
authors: CH
authors: Chen
authors: Institute of Atomic and Molecular Science, Academia Sinica, Taipei, Taiwan.
authors: Lain-Jong
authors: LJ
authors: Li
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