Large-amplitude coherent spin waves exited by spin-polarized current in nanoscale spin valves

Abstract

We present spectral measurements of spin-wave excitations driven by direct spinpolarized current in the free layer of nanoscale Ir20Mn80/Ni80Fe20/Cu/Ni80Fe20 spin valves. The measurements reveal that large-amplitude coherent spin wave modes are excited over a wide range of bias current. The frequency of these excitations exhibits a series of jumps as a function of current due to transitions between different localized nonlinear spin wave modes of the Ni80Fe20 nanomagnet. We find that micromagnetic simulations employing the Landau-Lifshitz-Gilbert equation of motion augmented by the Slonczewski spin torque term (LLGS) accurately describe the frequency of the current-driven excitations including the mode transition behavior. However LLGS simulations give qualitatively incorrect predictions for the amplitude of excited spin waves as a function of current.

24 pages, 4 figures, submitted to Physical Review B; in the 1st revised version some references were corrected

References in corpus (5)

• Excitations of incoherent spin-waves due to spin-transfer torque
• Current-driven microwave oscillations in current perpendicular-to-plane spin-valve nanopillars
• Lateral length scales in exchange bias
• Stochastic theory of spin-transfer oscillator linewidths
• Ferromagnetic relaxation by magnon-induced currents

Cited by in corpus (15)

• Spin Transfer Torques
• Spin-Torque Driven Magnetization Dynamics: Micromagnetic Modelling
• Coupling efficiency for phase locking of a spin transfer oscillator to a microwave current
• Impact of the electrical connection of N Spin Transfer Oscillators on their synchronization : an analytical study
• Spin-Torque Ferromagnetic Resonance Measurements of Damping in Nanomagnets
• Transverse spin diffusion in ferromagnets
• Time-Domain Studies of Very-Large-Angle Magnetization Dynamics Excited by Spin Transfer Torques
• Inhomogeneous Gilbert damping from impurities and electron-electron interactions
• Experimental Test of Analytic Theory of Spin Torque Oscillator Dynamics
• Micromagnetic study of a spin-torque oscillator based on a magnetic nano-contact magnetized at an arbitrary angle
• Spin-Torque-Induced Rotational Dynamics of a Magnetic Vortex Dipole
• Magnetization oscillations induced by a spin-polarized current in a point-contact geometry: mode hopping and non-linear damping effects
• Non-stationary magnetization dynamics driven by spin transfer torque
• Microwave excitations associated with a wavy angular dependence of the spin transfer torque : model and experiments
• Micromagnetic simulations of persistent oscillatory modes excited by spin-polarized current in nanoscale exchange-biased spin valves