Enhancement in spin-torque efficiency by nonuniform spin current generated within a tapered nanopillar spin valve
arXiv:0711.2479 · doi:10.1103/PhysRevB.77.144423
Abstract
We examine the effect a spatially non-uniform spin current with a component polarized partially out of the plane has on a low saturation magnetization nanomagnet free layer. Micromagnetic simulations indicate that the spin torque efficiency acting upon the reversing nanomagnet can be enhanced through this process, resulting in faster switching with smaller currents. In doing so, we determine that micromagnetic structure within the nanomagnets can be beneficial for reversal processes. We verify this enhancement experimentally in devices with a tapered nanopillar geometry that generates a spin current polarized partly out of plane. Finally, to take even better advantage of these effects, we examine micromagnetically the benefits of a tapered three-magnetic-layer structure that further reduces reversal times while maintaining the thermal stability of the free layer.
22 pages, 5 figures, submitted to Phys. Rev. B
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- Spin-transfer-torque resonant switching and injection locking in presence of a weak external microwave field for spin valves with perpendicular materials
- Ultrafast switching of a nanomagnet by a combined out-of-plane and in-plane polarized spin-current pulse
- Micromagnetic study of electrical-field-assisted magnetization switching in MTJ devices
- A quasi-linear spin-torque nano-oscillator via enhanced negative feedback of power fluctuations