Low temperature line-width broadening in optical-conductivity spectra of the off-center rattling phonons in type-I clathrate Ba${}_8$Ga${}_{16}$Sn${}_{30}$

T. Mori, K. Iwamoto, S. Kushibiki +6

With a terahertz time-domain spectrometer (0.3 - 3.0 THz) we have measured the optical conductivity of the type-I clathrate Ba${}_8$Ga${}_{16}$Sn${}_{30}$ at temperatures from 300 K down…