Investigation of magnetic fluctuations in Tb2Sn2O7 ordered spin ice by high-resolution energy-resolved neutron scattering

We have studied magnetically frustrated Tb(2)Sn(2)O(7) by neutron diffraction and high-resolution energy-resolved neutron scattering. At 0.1 K, we observed short-range magnetic correlations with a typical scale of 4 A, close to the near-neighbor distance between Tb(3+) ions. This short-range order coexists with ferromagnetic correlations and long-range spin ice order at the scales of 18 and 190 A, respectively. Spin dynamics was investigated at a time scale down to 10(-9) s by energy-resolved experiments on a backscattering spectrometer. We observed a freezing of the spin dynamics for all length scales with a strong slowing down of the spin fluctuations when long-range order settles in. We discuss the spin fluctuations remaining in the ground state, in comparison with previous data obtained by muon spectroscopy.