Optical conductivity of rattling phonons in type-I clathrate Ba${}_8$Ga${}_{16}$Ge${}_{30}$

T. Mori, S. Goshima, K. Iwamoto +9

A series of infrared-active optical phonons have been detected in type-I clathrate Ba${}_8$Ga${}_{16}$Ge${}_{30}$ by terahertz time-domain spectroscopy. The conductivity spectra with the…