Time correlation function for a Cu-Mn spin glass

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Abstract
The self-correlation function xi (t) for a Cu-3 at.% Mn alloy has been determined with good statistical accuracy using conventional time-of-flight as well as the more sophisticated backscattering technique. Around the low-frequency (10 Hz) freezing temperature Tf the correlation function xi (t) shows a power-law decay, i.e. xi (t)=at-v with nu approximately 0.25 above Tf, but nu =0.1+or-0.02 and just below Tf. At lower temperatures (T/Tf approximately=0.75) xi (t) is best expressed as xi (t)=at-v+b log(t) and yields nu =0.4+or-0.1. At still lower temperatures (Tf) xi (t) can be expressed as xi (t)=c+at-v, with a value of nu which is consistent with nu approximately 0.5, predicted by recent mean-field theories as well as computer simulations. An important result of the measurements is that the mean correlation time tau 1e/ obeys the Vogel-Fulcher law suggesting a glass-like transition with Tg approximately=0.8 Tf(10 Hz).

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