Non-stationary magnetization dynamics driven by spin transfer torque

Abstract

This paper shows that the presence of two dynamical regimes, characterized by different precessional-axis, is the origin of the non-monotonic behavior of the output integrated power for large-amplitude magnetization precession driven by spin-polarized current in nanoscale exchange biased spin-valves. In particular, at the transition current between those two regimes exists an abruptly loss in the integrated output power. After the introduction of a time-frequency analysis of magnetization dynamics based on the wavelet transform, we performed a numerical experiment by means of micromagnetic simulations. Our results predicted that, together with a modulation of the frequency of the main excited mode of the magnetization precession, at high non-linear dynamical regime the instantaneous output power of the spin-torque oscillator can disappear and then reappear at nanosecond scale.

10 pages 4 figures, to be appear in Physical Review B

References in corpus (6)

• Magnetoresistance and spin-transfer torque in magnetic tunnel junctions
• Large-amplitude coherent spin waves exited by spin-polarized current in nanoscale spin valves
• Strong linewidth variation for spin-torque nano-oscillators as a function of in-plane magnetic field angle
• Time-Domain Studies of Very-Large-Angle Magnetization Dynamics Excited by Spin Transfer Torques
• Stochastic theory of spin-transfer oscillator linewidths
• Micromagnetic simulations of persistent oscillatory modes excited by spin-polarized current in nanoscale exchange-biased spin valves