Analysis of magnetization instability patterns in spin-transfer nano-oscillators

作者：Bonin R^*; d' Aquino M; Bertotti G; Serpico C; Mayergoyz I D

来源：European Physical Journal B, 2012, 85(1): 47.

DOI：10.1140/epjb/e2011-20505-3

The stability of large precessional magnetization motions induced by spin-polarized currents in spin-transfer nano-oscillators is discussed. Quantitative analytical predictions are obtained for the critical values of spin-polarized injected current and external magnetic field at which the oscillator magnetization precession becomes unstable. It is shown that the mechanism leading to instability is parametric resonance of well-defined pairs of magnetostatically coupled perturbation modes. The amplitude of these modes grows to large non-thermal values when the oscillator frequency matches the mean of the natural frequencies of the two coupled modes. Analytical predictions are obtained for the space-time structure and symmetry of the magnetization patterns that are formed at the instability. Analytical results are compared with numerical simulations of spin-transfer-driven magnetization dynamics.

• 出版日期2012-1