Muon-spin-rotation measurements in the kagomé lattice systems: Cr-jarosite and Fe-jarosite

We have examined the magnetic properties of the frustrated kagomé lattice spin systems KFe3(OH)6(SO4)2 (Fe-jarosite) and KCr3(OH)6(SO4)2 (Cr-jarosite) using the μSR technique. In Fe-jarosite, a clear muon precession signal in zero field was found below 55 K, corresponding to the long-range order of Fe moments. In Cr-jarosite spin fluctuations persist without clear signature of spin freezing even at T = 25 mK, far below Tg∼2 K where the history dependence in the magnetic susceptibility appears. © 1996 The American Physical Society.