Spectral Line Shape and Line Width of a Single-Mode Spin Torque Oscillator
ORAL
Abstract
Spin torque auto-oscillators are strongly nonlinear dynamical systems that are highly susceptible to external perturbations such as spin-polarized current and temperature. To understand the effect of thermal fluctuations on the oscillator dynamics, we measure power spectrum of single-mode spin torque oscillators based on a GMR nanocontact to a permalloy nanowire. Our measurements reveal deviations of the power spectral line shape from a simple Lorentzian. These deviations can be understood in terms of dephasing induced by the oscillator amplitude fluctuations. The measured spectral line shape is in a good agreement with a recent analytic theory of spin torque oscillator dynamics at a non-zero temperature [1]. We show that precise measurements of the line shape give information on important oscillator parameters such as Gilbert damping in the large-amplitude regime of current-driven magnetization dynamics. [1] V. S. Tiberkevich, A. N. Slavin, J.-V. Kim, Phys. Rev. B 78, 092401 (2008).
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Authors
Ilya Krivorotov
University of California Irvine, Department of Physics and Astronomy, University of California, Irvine, University of California, Irvine
Carl Boone
University of California Irvine, Department of Physics and Astronomy, University of California, Irvine, University of California, Irvine
Jian Zhu
University of California Irvine, Department of Physics and Astronomy, University of California, Irvine, University of California, Irvine
Xiao Cheng
University of California Irvine, Department of Physics and Astronomy, University of California, Irvine, University of California, Irvine
Jordan Katine
Hitachi Global Storage Technologies, San Jose Research Center, San Jose, CA 95135, Hitachi Global Storage Technologies
