声子
拉曼光谱
异质结
凝聚态物理
材料科学
共振(粒子物理)
单层
超晶格
堆积
范德瓦尔斯力
光学
分子物理学
纳米技术
物理
原子物理学
核磁共振
分子
量子力学
作者
Saidur Rahman,Xueqian Sun,Yi Zhu,Yuerui Lu
出处
期刊:ACS Nano
[American Chemical Society]
日期:2022-11-28
卷期号:16 (12): 21505-21517
被引量:8
标识
DOI:10.1021/acsnano.2c10092
摘要
Twisted van der Waals heterostructures are known to induce surprisingly diverse and intriguing phenomena, such as correlated electronic phase and unconventional optical properties. This can be realized by controlled rotation of adjacent atomic planes, which provides an uncommon way to manipulate inelastic light-matter interactions. Here, we discover an extraordinary blue shift of 5-6 wavenumbers for high-frequency phonon modes in WS2/WSe2 twisted heterobilayers, captured meticulously using Raman spectroscopy. Phonon spectra displace rapidly over a subtle change in interlayer twist angle owing to heterostrain and atomic reconstruction from the Moiré pattern. First-order linear coefficients of the phonon modes in twisted heterostructures are further found to increase largely compared to their monolayer counterpart and vary immensely with the twist angle. Exceptional and extravagant enhancement of up to 50-fold is observed in the Raman vibrational intensity at a specific twist angle; this is largely influenced by the resonance process derived from a simple critical twist angle model. In addition, we depict how the resonance can be modulated by changing the thermal conditions and also the stacking angle. Therefore, our work further highlights the twist-driven phonon dynamics in pristine two-dimensional heterostructures, adding vital insight into Moiré physics and promoting comprehensive understanding of structural and optical properties in Moiré superlattices.
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