Neutron spin echo studies of SrCr8Ga 4O19

We performed neutron spin echo (NSE) measurements of the geometrically frustrated Kagomélattice spin system SrCrxGa 12− xO19 (SCGO) (x = 8), with a momentum transfer at Q = 1.4 Å −1. At high temperature (T ≅ 20K), the echo intensity quickly drops to zero, reflecting fast spin fluctuations. Below T ≅ 3.5K, we found a finite intensity persisting to long times, up to t ≌ 1ns. The persisting intensity increases with decreasing temperature, corresponding to the build-up of a static order parameter.