Muon spin relaxation in NaV 2O 5 in its spin-Peierls phase

Abstract

Depolarization measurements of muons have been carried out on NaV 2O 5 in the temperature range from 6 K up to 150 K, through the spin-Peierls transition at T sP=33 K. Surprisingly, the relaxation is fitted throughout to a stretched exponential, exp(−( λ( T) t) β( T) ). We observe a dramatic rise in the relaxation rate λ below T sP. On the other hand, the exponent β is greater than 1 above the transition temperature but falls to below 1 3 at 6 K, as in frustrated systems. Furthermore, the fit of the data shows that a fraction of muons is rapidly depolarized when implanted in the sample.