Double ferromagnetic resonance and configuration-dependent dipolar coupling in unsaturated arrays of bistable magnetic nanowires

Medina, Joaquin De La Torre;Piraux, Luc;Olais Govea, J. M.;Encinas, Armando
(2010) Physical review. B, Condensed matter and materials physics — Vol. 81, n° 14 (2010)

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Authors
  • Medina, Joaquin De La TorreUCLouvain
    Author
  • Piraux, LucUCLouvain
    Author
  • Olais Govea, J. M.
    Author
  • Encinas, ArmandoUCLouvain
    Author
Abstract
The ferromagnetic resonance properties in arrays of low diameter bistable nanowires have been studied. Measurements performed in the frequency swept mode show that in nonsaturated states, wires magnetized in the positive and negative direction absorb at different frequencies giving place to spectra with two absorption peaks. Moreover, the positive and negative wires obey different dispersion relations, which allow interpreting their different frequency-field dependence in terms of the uniform precession mode. Measurements along sets of first-order reversal curves allow to determine the dipolar interaction field as a function of the magnetic state. The configuration dependence of the interaction field is found to be proportional to the value of the dipolar interaction field of the saturated state. An analytical mean-field expression, which explicitly incorporates the dependence of the interaction field with the magnetic configuration, is proposed and used to obtain a general expression for both the effective field and the dispersion relation, which describes with remarkable agreement the ferromagnetic resonance measurements in saturated and nonsaturated states.
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Citations

Medina, J. D. L. T., Piraux, L., Olais Govea, J. M., & Encinas, A. (2010). Double ferromagnetic resonance and configuration-dependent dipolar coupling in unsaturated arrays of bistable magnetic nanowires. Physical review. B, Condensed matter and materials physics, 81(14). https://doi.org/10.1103/PhysRevB.81.144411 (Original work published 2010)