Raman scattering study on Kondo semiconductors of CeRhSb and CeNiSn.

本研究的目的是通过拉曼散射来阐明CeRhSb和CeNiSn近道半导体的微观机理。在室温至5K的温度范围内测量了拉曼散射光谱的偏振依赖性。根据正模计算的结果，在0 ~ 250cm^-^1之间的能量区域观测到的峰被指定为声子。其中，CeRhSb的3个声子和CeNiSn的1个声子的能量表现出反常的温度依赖性。由于这些模态是Ce的振动，这种依赖关系表明在近藤态中存在磁波动和晶格振动之间的相互作用。在拉曼散射光谱中也观察到宽背景光谱。其低能区的强度在30K以下减小。赝隙的v形态密度很好地解释了谱的形状。所得参数与比热和核磁共振报告值相似。这种对LaNiSn的黑磨光谱的抑制还没有被观察到。因此，背景光谱低能区的抑制源于局域化的4f和传导电子之间的杂化效应导致的自旋间隙态的出现。

The purpose of this research is to clarify the microscopic mechanism of the Kondo semiconductors of CeRhSb and CeNiSn by Raman scattering. The detailed polarization dependence of Raman scattering spectra has been measured in the temperature region between room temperature and 5K.The peaks, observed in the energy region between 0 and 250cm^-^1, are assigned as the phonons, judging from the results of the normal mode calculation. Among them, three phonons of CeRhSb and one of CeNiSn show the anomalous temperature dependence of their energy. Since these modes are the vibrations of Ce, the dependence shows the existence of the interaction between magnetic fluctuation and lattice vibration in the Kondo states. The broad background spectrum has been also observed in the Raman scattering spectra. Its intensity of the low energy region decreases below 30K.The spectral shape is well explained by the V-shaped state density of the pseudo-gap. The obtained parameters are similar to the reported values by specific heat and NMR.Such suppression of the hack-ground spectra of LaNiSn has not been observed. Therefore, the suppression of the low energy region of the back-ground spectra is originated from the appearance of the spin gap state due to the hybridization effect between the localized 4f and conduction electrons.