Microwave excitations associated with a wavy angular dependence of the spin transfer torque : model and experiments

Abstract

The spin transfer torque (STT) can lead to steady precession of magnetization without any external applied field in magnetic spin valve where the magnetic layer have very different spin diffusion length. This effect is associated with an unusual angular dependence of the STT, called "wavy" (WAD-STT), predicted in the frame of diffusive models of spin transfer. In this article, we present a complete experimental characterization of the magnetization dynamics in the presence of a WAD-STT. The results are compared to the prediction of the magnetization dynamics obtained by single domain magnetic simulations (macrospin approximation). The macrospin simulations well reproduced the main static and dynamical experimental features (phase diagram, R(I) curves, dependence of frequency with current and field) and suggest that the dynamical excitations observed experimentally are associated with a large angle out-of-plane precession mode. The present work validates the diffusive models of the spin transfer and underlines the role of the spin accumulation and the spin relaxation effects on the STT.

References in corpus (21)

• Microwave Oscillations of a Nanomagnet Driven by a Spin-Polarized Current
• Current-driven Magnetization Reversal and Spin Wave Excitations in Co/Cu/Co Pillars
• Direct-Current Induced Dynamics in Co90Fe10/Ni80Fe20 Point Contacts
• Anatomy of Spin-Transfer Torque
• Non-collinear Magnetoelectronics
• The Role of Spin-Dependent Interface Scattering in Generating Current-Induced Torques in Magnetic Multilayers
• Shaped angular dependence of the spin transfer torque and microwave generation without magnetic field
• Non-collinear spin transfer in Co/Cu/Co multilayers
• Mechanisms limiting the coherence time of spontaneous magnetic oscillations driven by DC spin-polarized currents
• Spin-transfer in diffusive ferromagnet-normal metal systems with spin-flip scattering
• Large-amplitude coherent spin waves exited by spin-polarized current in nanoscale spin valves
• Magnetization reversal by injection and transfer of spin: experiments and theory
• Controlled normal and inverse magnetoresistance and current-driven magnetization switching in magnetic nanopillars
• Spin-Transfer Excitations of Permalloy Nanopillars for Large Applied Currents
• Switching Current vs. Magnetoresistance in Magnetic Multilayer Nanopillars
• Magnetization precession due to a spin polarized current in a thin nanoelement: numerical simulation study
• Time-Resolved Spin Torque Switching and Enhanced Damping in Py/Cu/Py Spin-Valve Nanopillars
• Current-driven destabilization of both collinear configurations in asymmetric spin-valves
• Non-monotonic angular magnetoresistance in asymmetric spin valves
• Reducing the critical switching current in nanoscale spin valves
• A numerical method to solve the Boltzmann equation for a spin valve

Cited by in corpus (6)

• Current-induced dynamics in non-collinear dual spin-valves
• Current-pulse-induced magnetic switching in standard and nonstandard spin-valves
• Angular momentum transfer torques in spin valves with perpendicular magnetization
• Sustained RF oscillations from thermally induced spin-transfer torque
• Computational study of microwave oscillations in absence of external field in nonstandard spin valves in the diffusive transport limit
• From Spin Torque Nano-Oscillators to Memristors: Multi-Functional Nanodevices for Advanced Computing