title: Images of a spin-torque-driven magnetic nano-oscillator.
abstract: We present the first space- and time-resolved images of the spin-torque-induced steady-state oscillation of a magnetic vortex in a spin-valve nanostructure. We find that the vortex structure in a nanopillar is considerably more complicated than the 2D idealized structure often-assumed, which has important implications for the driving efficiency. The sense of the vortex gyration is uniquely determined by the vortex core polarity, confirming that the spin-torque acts as a source of negative damping even in such a strongly nonuniform magnetic system. The orbit radius is ∼10  nm, in agreement with micromagnetic simulations.
authors: Department of Applied Physics, Stanford University, Stanford, California 94305, USA.
authors: X W
authors: XW
authors: Yu
authors: V S
authors: VS
authors: Pribiag
authors: Y
authors: Y
authors: Acremann
authors: A A
authors: AA
authors: Tulapurkar
authors: T
authors: T
authors: Tyliszczak
authors: K W
authors: KW
authors: Chou
authors: B
authors: B
authors: Bräuer
authors: Z-P
authors: ZP
authors: Li
authors: O J
authors: OJ
authors: Lee
authors: P G
authors: PG
authors: Gowtham
authors: D C
authors: DC
authors: Ralph
authors: R A
authors: RA
authors: Buhrman
authors: J
authors: J
authors: Stöhr