Spin-torque driven magnetic vortex self-oscillations in perpendicular magnetic fields

Finocchio, G.; Pribiag, V. S.; Torres, L.; Buhrman, R. A.; Azzerboni, B.
March 2010
Applied Physics Letters;3/8/2010, Vol. 96 Issue 10, p102508
Academic Journal
We have employed complete micromagnetic simulations to analyze dc current driven self-oscillations of a vortex core in a spin-valve nanopillar in a perpendicular field by including the coupled effect of the spin-torque and the magnetostatic field computed self-consistently for the entire spin-valve. The vortex in the thicker nanomagnet moves along a quasielliptical trajectory that expands with applied current, resulting in “blueshifting” of the frequency, while the magnetization of the thinner nanomagnet is nonuniform due to the bias current. The simulations explain the experimental magnetoresistance-field hysteresis loop and yield good agreement with the measured frequency versus current behavior of this spin-torque vortex oscillator.


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