title: Magnetic density of states at low energy in geometrically frustrated systems.
abstract: Using muon-spin-relaxation measurements we show that the pyrochlore compound Gd(2)Ti(2)O(7), in its magnetically ordered phase below approximately 1 K, displays persistent spin dynamics down to temperatures as low as 20 mK. The characteristics of the induced muon relaxation can be accounted for by a scattering process involving two magnetic excitations, with a density of states characterized by an upturn at low energy and a small gap depending linearly on the temperature. We propose that such a density of states is a generic feature of geometrically frustrated magnetic materials.
authors.affiliation: CEA/DSM/Département de Recherche Fondamentale sur la Matière Condensée, Grenoble, France.
authors.forename: A
authors.initials: A
authors.lastname: Yaouanc
authors.forename: P Dalmas
authors.initials: PD
authors.lastname: de Réotier
authors.forename: V
authors.initials: V
authors.lastname: Glazkov
authors.forename: C
authors.initials: C
authors.lastname: Marin
authors.forename: P
authors.initials: P
authors.lastname: Bonville
authors.forename: J A
authors.initials: JA
authors.lastname: Hodges
authors.forename: P C M
authors.initials: PC
authors.lastname: Gubbens
authors.forename: S
authors.initials: S
authors.lastname: Sakarya
authors.forename: C
authors.initials: C
authors.lastname: Baines