Spin tunneling and topological selection rules for integer spins

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.

4 pages, 3 EPS figures, REVTeX

References in corpus (3)

• Spin Tunneling and Phonon-assisted Relaxation in Mn12-acetate
• Oscillatory Tunnel Splittings in Spin Systems: A Discrete Wentzel-Kramers-Brillouin Approach
• Reply to the comment of Chudnovsky&Garanin on "Spin relaxation in Mn12-acetate"

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