Abstract
We consider a large spin S in the magnetic field parallel to the uniaxial crystal field, interacting with nuclear spins via Hamiltonian with at temperature T. Tunneling splittings and the selection rules for the resonant values of are obtained perturbatively. The quantum coherence exists at while at the coherence is destroyed and the relaxation of S is described by a stretched dependence which can be close to under certain conditions. Relevance to acetate is discussed.
- Received 4 November 1999
DOI:https://doi.org/10.1103/PhysRevB.61.12204
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