title: Existence of an orientational electric dipolar response in c60 single crystals.
abstract: The dielectric constant in and conductivity sigma of undoped C(60) single crystals have been measured as a function of temperature, 10 K < T < 330 K, and frequency, 0.2 kilohertz < f < 100 kilohertz. On cooling below the first-order structural phase transition at 260 K, a Debye-like relaxational contribution to the dielectric response is observed, which requires the presence of permanent electric dipoles. The relaxation rate is thermally activated with a broad distribution of energies centered at 270 millielectron volts. The existence of a dipole moment in C(60) is unexpected, because it is precluded by symmetry for the pure ordered cubic phase. These data suggest that the high degree of frozen-in orientational disorder of the C(60) molecules is responsible for the existence of electric dipolar activity.
authors.forename: G B
authors.initials: GB
authors.lastname: Alers
authors.forename: B
authors.initials: B
authors.lastname: Golding
authors.forename: A R
authors.initials: AR
authors.lastname: Kortan
authors.forename: R C
authors.initials: RC
authors.lastname: Haddon
authors.forename: F A
authors.initials: FA
authors.lastname: Theil