Polarized Raman spectroscopy on topological semimetal Co3Sn2S2
Polarized Raman spectroscopy on topological semimetal Co3Sn2S2
复制标题
拓扑半金属 Co3Sn2S2 的偏振拉曼光谱
DOI：
10.1002/jrs.6459
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发表时间：
2022
影响因子：
2.5
通讯作者：
Miyauchi Yuhei
中科院分区：
文献类型：
--
作者：
Tanaka Kenya;Nishihara Taishi;Takakura Akira;Segawa Yasutomo;Matsuda Kazunari;Miyauchi Yuhei
我们提出了偏振拉曼光谱的拓扑半金属Co 3Sn 2S 2，这是最近被证明主机Weyl半金属相。斯托克斯拉曼光谱是用平行于Co 3Sn 2S 2的c轴的入射光获得的。两个主要的声子拉曼峰在289和386 cm− 1处观察到连续的背景发射信号。低波数（289 cm−1）峰的强度显示没有偏振依赖性。高波数（386 cm-1）峰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极化的面内晶体取向无关，这是Co 3Sn 2S 2晶胞的点群对称性的表现。根据群论和拉曼张量分析，低波数和高波数拉曼信号分别归属于具有和对称性的Γ点声子模。此外，线形分析表明，高波数模式具有Breit-Wigner-Fano函数很好地描述的非对称峰特征。这些结果表明，声子散射与连续电子背景之间的Fano共振与费米能级附近的低能激发有关。澄清的声子能量和对称性，以及电子的贡献的拉曼散射，将不仅是有用的指纹，以方便地验证实验生长或理论计算的晶体结构，但也建议的重要性拉曼光谱作为一种有效的工具，研究低能量激发和它们的相互作用在Co 3Sn 2S 2。
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 thec‐axis of Co3Sn2S2. Two major phonon Raman peaks were observed at 289 and 386 cm−1over 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 thepoint 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 withandsymmetries, respectively. Furthermore, line shape analyses revealed that the high‐wavenumbermode exhibited asymmetric peak feature well described by the Breit–Wigner–Fano function. These results suggest the Fano resonance between thephonon 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.