We report enhanced spin-torque oscillator results obtained in spin-valve nanopillars. When biased within the optimal range of a moderate, <=600 Oe, hard axis field, the spin-torque-driven oscillations exhibit a sharp increase in power and a sharply narrowed linewidth, <=10MHz, which, based on micromagnetic simulations, we ascribe to a transition from incoherent to coherent dynamics. The simulations indicate that the coherent dynamics are enabled by the combination of strong coupling between the two oscillator end modes of the magnetic free layer and strong non-linear damping arising from a non-uniform magnetization that leads to a spatially varying antidamping spin torque.
Coherent and incoherent spin torque oscillations in a nanopillar magnetic spin-valve
FINOCCHIO, Giovanni;
2013-01-01
Abstract
We report enhanced spin-torque oscillator results obtained in spin-valve nanopillars. When biased within the optimal range of a moderate, <=600 Oe, hard axis field, the spin-torque-driven oscillations exhibit a sharp increase in power and a sharply narrowed linewidth, <=10MHz, which, based on micromagnetic simulations, we ascribe to a transition from incoherent to coherent dynamics. The simulations indicate that the coherent dynamics are enabled by the combination of strong coupling between the two oscillator end modes of the magnetic free layer and strong non-linear damping arising from a non-uniform magnetization that leads to a spatially varying antidamping spin torque.Pubblicazioni consigliate
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