Frequency-dependent susceptibility and Mossbauer experiments in CsNiFeF6

AC susceptibility measurements have been performed between 19 Hz and 50 kHz on the insulating spin glass compound CsNiFeF 6 . Very large well marked maxima have been found for the in-phase chi ' and out-of-phase chi " susceptibilities. A slight frequency dependence has been observed. The temperatures T m of the maxima of chi ' follow a Vogel-Fulcher law with (T m (10)-T 0 )/T m (10)=0.081. The high-temperature side of the chi "-curves is almost independent of the frequency. The Mossbauer experiments for the same sample show that a local spin polarisation occurs at a temperature close to the point where the chi "-curves drop to zero. The analysis of the Mossbauer spectrum at 1.4K shows that the magnetic moments of the Fe ions are not randomly oriented with respect to the local axes of the electric field gradient.