title: Generalized spin-glass relaxation.
abstract: Spin relaxation close to the glass temperature of CuMn and AuFe spin glasses is shown, by neutron spin echo, to follow a generalized exponential function which explicitly introduces hierarchically constrained dynamics and macroscopic interactions. The interaction parameter is directly related to the normalized Tsallis nonextensive entropy parameter q and exhibits universal scaling with reduced temperature. At the glass temperature q=5/3 corresponding, within Tsallis' q statistics, to a mathematically defined critical value for the onset of strong disorder and nonlinear dynamics.
authors.affiliation: School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, United Kingdom.
authors.forename: R M
authors.initials: RM
authors.lastname: Pickup
authors.forename: R
authors.initials: R
authors.lastname: Cywinski
authors.forename: C
authors.initials: C
authors.lastname: Pappas
authors.forename: B
authors.initials: B
authors.lastname: Farago
authors.forename: P
authors.initials: P
authors.lastname: Fouquet