谷相干的直接识别及其在单层二维半导体中的操作

IF 16 1区 材料科学 Q1 CHEMISTRY, MULTIDISCIPLINARY
Haonan Wang, Keisuke Shinokita, Kenji Watanabe, Takashi Taniguchi, Satoru Konabe* and Kazunari Matsuda*, 
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引用次数: 0

摘要

由于逆对称破缺和强自旋-轨道耦合,单层二维半导体具有谷自由度。K谷和K′谷的激发态具有谷伪自旋的信息,这对谷伪自旋布洛赫球的量子态操纵是有用的。然而,由于在光发射过程中会发生谷间退相干,因此在时域上直接探测谷相干性仍然具有挑战性。在此,我们展示了在单层WSe2器件中使用偏振干涉法直接测量K和K '谷激子之间的谷间相干性。实验结果表明,根据激发功率和温度的不同,谷间相干时间在200 ~ 300 fs之间。此外,在电子和空穴载流子掺杂下,通过施加外部偏置电压,观察到谷间相干时间和线极化程度的不对称调制,表明在高电子掺杂下,谷间相干时间延长至400 fs。阐明了K和K '谷激子间谷退相干的极性和载流子掺杂依赖性的潜在机制。本文的结果为直接探测时域谷相干性和阐明谷伪自旋量子态操纵的退相干过程的潜在机制提供了可行的方法。
本文章由计算机程序翻译,如有差异,请以英文原文为准。

Direct Identification of Valley Coherence and Its Manipulation in Monolayer Two-Dimensional Semiconductor

Direct Identification of Valley Coherence and Its Manipulation in Monolayer Two-Dimensional Semiconductor

Monolayer two-dimensional semiconductors are endowed with valley degrees of freedom due to broken inversion symmetry and strong spin–orbit coupling. The excited states in the K and K′ valleys possess information on valley pseudospin, which is useful for quantum-state manipulation in the valley pseudospin Bloch sphere. However, since intervalley decoherence occurs during light emission, directly probing valley coherence in the time domain has remained challenging. Herein, we have demonstrated the direct measurement of intervalley coherence between K and K′ valley excitons using polarized interferometry in a monolayer WSe2 device. The experimental results showed that the intervalley coherence time is in the range of 200–300 fs, depending on the excitation power and temperature. Moreover, an asymmetric modulation of the intervalley coherence time as well as the degree of linear polarization was observed under electron and hole carrier doping by applying an external bias voltage, demonstrating an extended valley coherence time reaching 400 fs under high electron doping. The underlying mechanism of the polarity and carrier doping dependence of valley decoherence between K and K′ valley excitons was elucidated. The results presented herein offer a viable approach for directly probing valley coherence in the time domain and elucidating the underlying mechanism of the decoherence process toward quantum-state manipulation of valley pseudospin.

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来源期刊
ACS Nano
ACS Nano 工程技术-材料科学:综合
CiteScore
26.00
自引率
4.10%
发文量
1627
审稿时长
1.7 months
期刊介绍: ACS Nano, published monthly, serves as an international forum for comprehensive articles on nanoscience and nanotechnology research at the intersections of chemistry, biology, materials science, physics, and engineering. The journal fosters communication among scientists in these communities, facilitating collaboration, new research opportunities, and advancements through discoveries. ACS Nano covers synthesis, assembly, characterization, theory, and simulation of nanostructures, nanobiotechnology, nanofabrication, methods and tools for nanoscience and nanotechnology, and self- and directed-assembly. Alongside original research articles, it offers thorough reviews, perspectives on cutting-edge research, and discussions envisioning the future of nanoscience and nanotechnology.
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