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Exploration of Fermi-Pasta-Ulam Behavior in a Magnetic System
Jeramy Lewis1, Robert E Camley1,2, Nicholas R Anderson2
1Center for Magnetism and Magnetic Nanostructures, University of Colorado, Colorado Springs, Colorado Springs, Colorado 80918, USA.
Abstract:
We study nonlinear spin motion in one-dimensional magnetic chains. We find significant differences from the classic Fermi-Pasta-Ulam (FPU) problem examining nonlinear elastic motion in a chain. We find that FPU behavior, the transfer of energy among low order eigenmodes, does not occur in magnetic systems with only exchange and external fields, but does exist if a uniaxial anisotropy is also present. The FPU behavior may be altered or turned off through the magnitude and orientation of an external magnetic field. A realistic micromagnetic model shows such behavior could be measurable.
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