Ground state of the geometrically frustrated compound Tb2Sn2O7

Despite the observation of magnetic neutron reflections at low temperatures, muon-spin experiments have suggested the ground state of the geometrically frustrated magnetic material Tb2Sn2O7 to be dynamical. This unique situation requires additional characterizations of this magnetic ground state. Here we report a neutron spin-echo investigation which supports the existence of a dynamical component in the ground state. This result is backed by a thorough analysis of the diffraction profiles. A physical model is put forward in which the energy splitting between the ground and first excited states of the Tb3+ ion is comparable to other energies present in this frustrated system.