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Spin tunneling and topological selection rules for integer spins

Michael N. Leuenberger·Daniel Loss
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Abstract

We present topological interference effects for the tunneling of a single large spin, which are caused by the symmetry of a general class of magnetic anisotropies. The interference originates from spin Berry phases associated with different tunneling paths exposed to the same dynamics. Introducing a generalized path integral for coherent spin states, we evaluate transition amplitudes between ground as well as low-lying excited states. We show that these interference effects lead to topological selection rules and spin-parity effects for integer spins that agree with quantum selection rules and which thus provide a generalization of the Kramers degeneracy to integer spins. Our results apply to the molecular magnets Mn12 and Fe8.

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Michael N. Leuenberger, Daniel Loss. 2000-12-04. Spin tunneling and topological selection rules for integer spins. https://doi.org/10.1103/physrevb.63.054414

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