title: Probing the spin polarization of current by soft x-ray imaging of current-induced magnetic vortex dynamics.
abstract: Time-resolved soft x-ray transmission microscopy is applied to image the current-induced resonant dynamics of the magnetic vortex core realized in a micron sized Permalloy disk. The high spatial resolution better than 25 nm enables us to observe the resonant motion of the vortex core. The result also provides the spin polarization of the current to be 0.67+/-0.16 for Permalloy by fitting the experimental results with an analytical model in the framework of the spin-transfer torque.
authors.affiliation: Institute for Chemical Research, Kyoto University, Uji 611-0011, Japan.
authors.forename: Shinya
authors.initials: S
authors.lastname: Kasai
authors.forename: Peter
authors.initials: P
authors.lastname: Fischer
authors.forename: Mi-Young
authors.initials: MY
authors.lastname: Im
authors.forename: Keisuke
authors.initials: K
authors.lastname: Yamada
authors.forename: Yoshinobu
authors.initials: Y
authors.lastname: Nakatani
authors.forename: Kensuke
authors.initials: K
authors.lastname: Kobayashi
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kohno
authors.forename: Teruo
authors.initials: T
authors.lastname: Ono