Spin dynamics and tunneling of the Neel vector in the Fe10 magnetic wheel -: art. no. 184405

The spin dynamics of a ring-shaped molecule comprising 10 iron(III) ions (s=5/2) is studied by inelastic neutron scattering. Exchange integrals and single-ion anisotropy parameters are determined by studying several intermultiplet excitations. Difficulties associated with the dimension of the Hilbert space are overcome by exploiting both the irreducible tensor operator technique and the Lanczos algorithm. By calculating the time correlation function of the Neel vector we show that the low-temperature spin dynamics of Fe-10 is only approximately described by the semiclassical picture of tunneling of the Neel vector.