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Microwave Oscillations of a Nanomagnet Driven by a Spin-Polarized Current

S. I. Kiselev·J. C. Sankey·I. N. Krivorotov·N. C. Emley·R. J. Schoelkopf·R. A. Buhrman·D. C. Ralph
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Abstract

We describe direct electrical measurements of microwave-frequency dynamics in individual nanomagnets that are driven by spin transfer from a DC spin-polarized current. We map out the dynamical stability diagram as a function of current and magnetic field, and we show that spin transfer can produce several different types of magnetic excitations, including small-angle precession, a more complicated large-angle motion, and a high-current state that generates little microwave signal. The large-angle mode can produce a significant emission of microwave energy, as large as 40 times the Johnson-noise background.

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S. I. Kiselev, J. C. Sankey, I. N. Krivorotov, N. C. Emley, R. J. Schoelkopf, R. A. Buhrman, D. C. Ralph. 2003-06-11. Microwave Oscillations of a Nanomagnet Driven by a Spin-Polarized Current. https://doi.org/10.1038/nature01967

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