Breakdown of the giant spin model in the magnetic relaxation of the Mn6 nanomagnets.

@article{Carretta2008BreakdownOT,
  title={Breakdown of the giant spin model in the magnetic relaxation of the Mn6 nanomagnets.},
  author={Stefano Carretta and Tatiana Guidi and P M Santini and Giuseppe Amoretti and Oliver Pieper and Bella Lake and Joris van Slageren and Fadi El Hallak and Wolfgang Wernsdorfer and H. Mutka and Margarita Russina and Constantinos J. Milios and Euan K. Brechin},
  journal={Physical review letters},
  year={2008},
  volume={100 15},
  pages={
          157203
        }
}
We study the spin dynamics in two variants of the high-anisotropy Mn6 nanomagnet by inelastic neutron scattering, magnetic resonance spectroscopy and magnetometry. We show that a giant-spin picture is completely inadequate for these systems and that excited S multiplets play a key role in determining the effective energy barrier for the magnetization reversal. Moreover, we demonstrate the occurrence of tunneling processes involving pair of states having different total spin. 

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References

SHOWING 1-3 OF 3 REFERENCES
Science 284
  • 133
  • 1999
Because of S mixing, S is not a good quantum number. We label the states by their leading S component
The T dependence of high-energy peaks is partially hidden by the presence of phonons in the same energy range