Spin-torque driven ferromagnetic resonance in a nonlinear regime

W. Chen, G. De Loubens, J. M.L. Beaujour, J. Z. Sun, A. D. Kent

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    Abstract

    Spin-valve based nanojunctions incorporating Co∫Ni multilayers with perpendicular anisotropy were used to study spin-torque driven ferromagnetic resonance (ST-FMR) in a nonlinear regime. Perpendicular field swept resonance lines were measured under a large amplitude microwave current excitation, which produces a large angle precession of the Co∫Ni layer magnetization. With increasing rf power the resonance lines broaden and become asymmetric, with their peak shifting to lower applied field. A nonhysteretic step jump in ST-FMR voltage signal was also observed at high powers. The results are analyzed in terms of the foldover effect of a forced nonlinear oscillator and compared to macrospin simulations. The ST-FMR nonhysteretic step response may have applications in frequency and amplitude tunable nanoscale field sensors.

    Original languageEnglish (US)
    Article number172513
    JournalApplied Physics Letters
    Volume95
    Issue number17
    DOIs
    StatePublished - Nov 10 2009

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    ASJC Scopus subject areas

    • Physics and Astronomy (miscellaneous)

    Cite this

    Chen, W., De Loubens, G., Beaujour, J. M. L., Sun, J. Z., & Kent, A. D. (2009). Spin-torque driven ferromagnetic resonance in a nonlinear regime. Applied Physics Letters, 95(17), [172513]. https://doi.org/10.1063/1.3254242