title: Neutron spin-echo investigation of slow spin dynamics in kagomé-bilayer frustrated magnets as evidence for phonon assisted relaxation in SrCr9xGa12-9xO19.
abstract: A neutron spin-echo investigation of the low temperature spin dynamics in two well-characterized kagomé bilayer compounds SrCr9xGa12-9xO19 (x=0.95, SCGO) and Ba2Sn2ZnCr7xGa10-7xO22 (x=0.97, BSZCGO) reveals two novel features. One is the slowing down of the relaxation rate without critical behavior at Tg, where a macroscopic spin-glass-like freezing occurs. The second is, in SCGO at 4 K (approximately Tg)<T<7 K, the relaxation rate activation energy Ea=7+/-0.4 meV, equal to the energy of a phonon mode, pointing out the role of spin-lattice coupling.
authors.affiliation: Institut Laue-Langevin, Boîte Postale 156X, F-38042 Grenoble Cedex 9, France. mutka@ill.fr
authors.forename: H
authors.initials: H
authors.lastname: Mutka
authors.forename: G
authors.initials: G
authors.lastname: Ehlers
authors.forename: C
authors.initials: C
authors.lastname: Payen
authors.forename: D
authors.initials: D
authors.lastname: Bono
authors.forename: J R
authors.initials: JR
authors.lastname: Stewart
authors.forename: P
authors.initials: P
authors.lastname: Fouquet
authors.forename: P
authors.initials: P
authors.lastname: Mendels
authors.forename: J Y
authors.initials: JY
authors.lastname: Mevellec
authors.forename: N
authors.initials: N
authors.lastname: Blanchard
authors.forename: G
authors.initials: G
authors.lastname: Collin