Noise-induced switching between vortex states with di erent polarization in classical two-dimensional easy-plane magnets
نویسندگان
چکیده
In the 2-dimensional anisotropic classical Heisenberg model with XY-symmetry there are nonplanar vortices which exhibit a localized structure of the z-components of the spins around the vortex center. We study how thermal noise induces a transition of this structure from one polarization to the opposite one. We describe the vortex core by a discrete Hamiltonian and consider a stationary solution of the Fokker-Planck equation. We nd a bimodal distribution function and calculate the transition rate using Langer's instanton theory (1969). The result is compared with Langevin dynamics simulations for the full many-spin model.
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