TY - JOUR T1 - Geometric-Phase-Effect Tunnel-Splitting Oscillations in Single-Molecule Magnets with Fourth-Order Anisotropy Induced by Orthorhombic Distortion JF - EPL (Europhysics Letters) Y1 - 2009 A1 - Michael Foss-Feig A1 - Jonathan R. Friedman AB - 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. VL - 86 U4 - 27002 UR - http://arxiv.org/abs/0809.2289v2 CP - 2 J1 - Europhys. Lett. U5 - 10.1209/0295-5075/86/27002 ER -