Quadrupole Excitation in Tunnel Splitting Oscillation in Nano-Particle Mn12Mn_{12}

We analyze the interference between tunneling paths that occurs for a spin system with special Hamiltonian both for dipole and quadrupole excitation. Using an instanton approach, we find that as the strength of the second-order transverse anisotropy is increased, the tunnel splitting for both excitations are modulated, with zeros occurring periodically and the number of quenching points for quadrupole excitation decreases. This effect results from the interference of four tunneling paths connecting easy-axis spin orientations and occurs in the absence of any magnetic field.Comment: arXiv admin note: This paper has been withdrawn by arXiv administrators: v2 is withdrawn because it is unrelated to v1 and thus an inappropriate replacement. v1 is withdrawn because of excessive unattributed use of the work of other

Semiclassical description of anisotropic magnets for spin S=1

In this paper, nonlinear equations describing one-dimensional non-Heisenberg ferromagnetic model are studied by use of generalized coherent states in a real parameterization. Also dissipative spin wave equation for dipole and quadruple branches is obtained if there is a small linear excitation from the ground state