Coherent and incoherent spin torque oscillations in a nanopillar magnetic spin-valve

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, ≤10 MHz, which, based on microma...

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Bibliographic Details
Published in:	Applied physics letters Vol. 102; no. 25
Main Authors:	Braganca, P. M., Lee, O. J., Ozatay, O., Liu, L., Finocchio, G., Ralph, D. C., Buhrman, R. A.
Format:	Journal Article
Language:	English
Published:	24-06-2013
Online Access:	Get full text
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Summary:	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, ≤10 MHz, 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 anti-damping spin torque.
ISSN:	0003-6951 1077-3118
DOI:	10.1063/1.4812299