Polarized Raman scattering has been performed on CaC6 superconductor. We identify two of the three Raman active Eg phonon modes at 440 and 1508 cm-1 expected for the R-3m space group of CaC6. These first order scattering modes appear along with the D and G bands around 1300 cm-1 and 1600 cm-1 that are similar in origin to the corresponding bands in plain graphite. The intensities of the D and G bands in CaC6 correlate with degree of disorder. The D band arises from the double resonant Raman scattering process; its frequency shifts as a function of excitation energy with approximately 35 cm-1/eV. The double resonant Raman scattering probes phonon excitations with finite wave vector q. We estimate the characteristic spacing of structural defects to be on the scale of about 100 Angstrom by comparing the intensity of the D band and the 1508 cm-1 Eg mode in CaC6 to calibrated intensity ratio of analogous bands in disordered graphites. A sharp superconducting coherence peak at 24 cm-1 is observed below Tc.
Low-Temperature Phase of the Cd$_2$Re$_2$O$_7$ Superconductor: Ab initio Phonon Calculations and Raman Scattering
利用{\it ab initio}方法，我们报道了$1$ K $5d$超导体Cd $_2$ Re $_2$ O $_7$四元结构中空间群为$I4_{1}22$的声子软模.它诱导正交畸变的晶体结构所描述的空间群$F222$主机的超导状态。该新相具有比Cd $_2$ Re $_2$ O $_7$的其它已知晶体结构更低的总能量。对同位素富集样品$^{116}$ Cd $_2$ Re $_2{^{18}}$ O $_7$进行了全面的温度相关拉曼散射实验，不仅证实了已知的结构相变，而且还使我们能够确定$\sim 80$ K附近的一个新的特征温度区，低于该温度区，拉曼光谱随着几个尖锐模式和模式分裂的发展而发生显著变化。连同\textit{ab initio}声子计算的结果，我们把这些观察作为另一个相变到一个新的低温晶体结构的Cd $_2$ Re $_2$ O $_7$的强有力的证据。
Raman and photoluminescence spectroscopic studies on structural disorder in oxygen deficient Gd2Ti2O7-d single crystals
本文报道了在氩气氛下用光学浮区法生长的Gd_2Ti_2O_（7-d）单晶中氧空位引起的结构无序的拉曼光谱和光致发光光谱研究。Gd 2 Ti 2 O 7-d晶片中的氧空位随着在空气气氛中的热退火而减少。生长后热退火的X射线衍射摇摆曲线的半高宽从245降低到157角秒，光学透射率从23%增加到87%（在1000 nm处）。拉曼光谱研究表明，随着热退火，O-Gd-O（Eg）和Ti-O（A1 g）伸缩模的强度单调增加。由于这些模式是与调制的氧x参数，这是敏感的Ti-O八面体畸变，拉曼强度的增加表明在Gd 2 Ti 2 O 7-d的氧亚晶格的结构有序性的改善。此外，光致发光的研究也证实了拉曼分析方面的减少与氧空位作为一个功能的热退火的结构缺陷。这项研究表明，使用拉曼光谱探测Gd 2 Ti 2 O 7-d晶体中的结构无序的有效性。
Probing the multi spin-phonon coupling and local B-site disorder in Pr2CoFeO6 by Raman spectroscopy and correlation with its electronic structure by X-ray photoemission spectroscopy
