Geometric-phase-effect tunnel-splitting oscillations in single-molecule magnets with fourth-order anisotropy induced by orthorhombic distortionM. S. Foss-Feig and Jonathan R. Friedman
Department of Physics, Amherst College - Amherst, MA 01002-5000, USA
received 7 November 2008; accepted in final form 20 March 2009; published April 2009
published online 30 April 2009
We analyze the interference between tunneling paths that occurs for a spin system with both fourth-order and second-order transverse anisotropy. Using an instanton approach, we find that as the strength of the second-order transverse anisotropy is increased, the tunnel splitting is modulated, with zeros occurring periodically. This effect results from the interference of four tunneling paths connecting easy-axis spin orientations and occurs in the absence of any magnetic field.
75.45.+j - Macroscopic quantum phenomena in magnetic systems.
75.50.Xx - Molecular magnets.
03.65.Vf - Phases: geometric; dynamic or topological.
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