title: Dielectric constant of glasses: evidence for dipole-dipole interactions.
abstract: The 1 kHz real part chi(') of the dielectric constant of a structural glass (a-SiO(2+x)C(1+y)H(z)) was measured at low temperature T. Reducing the sample thickness h below 100 nm weakens the slope /delta(chi('))/delta (T) for T less than or approximately equal 0.1 K, for all measuring fields E. This contrasts with the predictions of the two-level system (TLS) model but is in agreement with the recently proposed delocalization of excitations derived from a field-induced TLS-TLS interaction mechanism. For small h this interaction is screened, which explains the h effects on chi('). Hence, interactions must play a key role in standard thick samples as soon as T less than or approximately equal 0.1 K.
authors.affiliation: DSM/DRECAM/LPS, C. E. Saclay, 91191 Gif-sur-Yvette Cedex, France. ladieu@drecam.cea.fr
authors.forename: F
authors.initials: F
authors.lastname: Ladieu
authors.forename: J
authors.initials: J
authors.lastname: Le Cochec
authors.forename: P
authors.initials: P
authors.lastname: Pari
authors.forename: P
authors.initials: P
authors.lastname: Trouslard
authors.forename: P
authors.initials: P
authors.lastname: Ailloud