Polarized neutron scattering study of the kagome antiferromagnet SrCr8Ga4O19

We present a polarized neutron scattering study on the magnetic fluctuation s on a powder sample of the SrCr8Ga4O19 compound. We use the D7 instrument at the ILL with the classical xyz-polarization analysis as well as time-of- flight analysis with Delta E approximate to 1 meV energy resolution. We ext ract the true magnetic scattering over a broader temperature range than tha t earlier examined in other studies. The results show that the broadly peak ed e-dependence observed in the elastic response at low T less than or equa l to 2 K persists in the dynamic signal up to T less than or equal to 50 K. At higher temperatures the peak broadens further into a structureless, par amagnetic like Q-dependence. Our data shows that the short-ranged dynamic A F correlations prevail up to a much higher temperature range than what had been earlier observed. (C) 1999 Elsevier Science B.V. All rights reserved.