拓扑半金属 Co3Sn2S2 的偏振拉曼光谱,Journal of Raman Spectroscopy

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拓扑半金属 Co3Sn2S2 的偏振拉曼光谱
Journal of Raman Spectroscopy ( IF 2.4 ) Pub Date : 2022-10-07 , DOI: 10.1002/jrs.6459
Kenya Tanaka ₁ , Taishi Nishihara ₁ , Akira Takakura ₁ , Yasutomo Segawa _{2,

3} , Kazunari Matsuda ₁ , Yuhei Miyauchi ₁

Affiliation

_{我们展示了拓扑半金属 Co 3} Sn ₂ S ₂的偏振拉曼光谱，最近显示它具有 Weyl 半金属相。使用平行于Co ₃ Sn ₂ S _2的c轴的入射光获得斯托克斯拉曼光谱。在连续背景发射信号上，在 289 和 386 cm ^-1处观察到两个主要的声子拉曼峰。低波数（289 cm ^-1）峰的强度不显示偏振相关性。高波数 (386 cm ^-1) 峰值和连续背景信号在入射光偏振方向上强烈偏振。这些响应几乎与入射偏振的面内晶体取向无关，正如

◂◽.▸ 丁_{3个 d}

_{Co 3} Sn ₂ S ₂晶胞的点群对称性。根据群论和拉曼张量分析，低波数和高波数拉曼信号归因于 Γ 点声子模式

乙_{G}

和

◂◽.▸ {一种}_{1个 G}

对称性，分别。此外，线形分析表明，高波数

◂◽.▸ {一种}_{1个 G}

模式表现出 Breit-Wigner-Fano 函数很好地描述的不对称峰特征。这些结果表明

◂◽.▸ {一种}_{1个 G}

声子散射与费米能量附近的低能量激发相关的连续电子背景。澄清的声子能量和对称性，以及电子对拉曼散射的贡献，不仅可以用作指纹来轻松验证实验生长或理论计算的晶体结构，而且还表明拉曼光谱作为研究的有效工具的重要性低能激发及其在 Co ₃ Sn ₂ S ₂中的相互作用。

"点击查看英文标题和摘要"

Polarized Raman spectroscopy on topological semimetal Co3Sn2S2

We present polarized Raman spectroscopy of the topological semimetal Co₃Sn₂S₂, which was recently shown to host a Weyl semimetal phase. Stokes Raman spectra were obtained with the incident light parallel to the c-axis of Co₃Sn₂S₂. Two major phonon Raman peaks were observed at 289 and 386 cm⁻¹ over continuous background emission signals. The intensity of the low-wavenumber (289 cm⁻¹) peak showed no polarization dependence. The high-wavenumber (386 cm⁻¹) peak and the continuous background signal were strongly polarized in the incident light polarization direction. These responses were almost independent of the in-plane crystal orientation to the incident polarization, as is the manifestation of the

◂◽.▸ D_{3 d}

point group symmetry of the unit cell of Co₃Sn₂S₂. According to the group theory and Raman tensor analyses, the low- and high-wavenumber Raman signals are attributed to Γ point phonon modes with

E_{g}

and

◂◽.▸ A_{1 g}

symmetries, respectively. Furthermore, line shape analyses revealed that the high-wavenumber

◂◽.▸ A_{1 g}

mode exhibited asymmetric peak feature well described by the Breit–Wigner–Fano function. These results suggest the Fano resonance between the

◂◽.▸ A_{1 g}

phonon scattering with the continuous electronic background associated with low energy excitations near the Fermi energy. The clarified phonon energies and symmetries, as well as the electronic contribution to the Raman scattering, will not only be useful as a fingerprint to readily verify the experimentally grown or theoretically calculated crystal structure but also suggest importance of Raman spectroscopy as an effective tool to study low energy excitations and their interactions in Co₃Sn₂S₂.

更新日期：2022-10-07

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