Generalized spin-glass relaxation.
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.
Pickup
R M
RM
School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, United Kingdom.
Cywinski
R
R
Pappas
C
C
Farago
B
B
Fouquet
P
P