The strong dynamics of magnetic correlations are observed by high field
57Fe Mössbauer investigations for the spin glasses
AuFe and Y(Fe, Al)2 in the temperature interval between
the freezing temperature Tf and
approximately 7 to 10Tf. All
recorded spectra can be analysed with a model which takes into account these
dynamics by allowing the formation of correlated states after a stochastically
varying time τoff and their decay after a time
τon, restricting the number of subspectra to the
different number of Fe atoms in the first neighbour shell. Whereas for the
different Fe environments, in addition to centre shift and quadrupole
splitting, different hyperfine fields of the two stochastically formed states
can always be resolved, the same set of τon and
τoff values was obtained for all subspectra above
approximately 4Tf. The external
field hinders the decay of the correlated regions. The temperature dependence
of ¿ on scales with
Tf and exhibits a power law with
exponents of –2 for the Fe-rich and –1 for the Fe-poor compounds.