Polarized Raman Scattering of In‐Plane Anisotropic Phonon Modes in α‑MoO3

作者：Youning Gong, Yanyu Zhao, Zhichao Zhou, Delong Li, Hu Mao, Qiaoliang Bao, Yupeng Zhang, Guo Ping Wang · 发表于：Advanced Optical Materials · 年份：2022 · DOI：10.1002/adom.202200038 · 被引用次数：59 · 研究领域：Transition Metal Oxide Nanomaterials、Thermal Radiation and Cooling Technologies、Nonlinear Optical Materials Studies

Abstract The recent discovery of in‐plane hyperbolic phonon polaritons in biaxial polar crystal—α‐MoO 3 , has aroused a huge research upsurge on anisotropic photonic quasiparticles in van der Waals materials. The physical origin of these highly anisotropic phonon polaritons is attributed to the strong anisotropy of crystal phonons. However, the orientation‐dependent phonon modes have not been fully understood from crystallographic point of view. This work systematically performs in situ angle‐resolved polarized Raman spectroscopy on α‐MoO 3 to investigate its anisotropic photo‐phonon interactions. The sample orientation and Raman tensors are unambiguously determined under different polarization configurations. Specifically, the in‐plane anisotropic phonon modes of α‐MoO 3 can be well characterized from the highly polarization‐dependent Raman‐active modes with periodic intensity variation. It can be concluded that these findings cannot only offer a better understanding of anisotropic phonon modes in α‐MoO 3 , but also provide a valuable reference for other anisotropic van der Waals crystals.