We report an experimental observation that indicates that a direct relation exists between the speed of the magnetic domain-wall (DW) motion and the magnitude of the perpendicular magnetic anisotropy (PMA) in Pt/Co/Pt films. It is found that by changing the thicknesses of the nonmagnetic Pt layers, the PMA magnitude can be varied significantly and the field-driven DW speed can also be modified by a factor of up to 50 under the same magnetic field. Interestingly, the DW speed exhibits a clear scaling behavior with respect to the PMA magnitude. A theory based on the DW creep criticality successfully explains the observed scaling exponent between the DW speed and the PMA magnitude. The presented results offer a method of maximizing the DW speed in DW-mediated nanodevices without altering the thickness of the magnetic Co layer.

We demonstrate that the spin pumping effect can be effectively suppressed with a nano-oxide layer. Spin pumping effect manifests itself by an enhancement of the Gilbert damping parameter in normal metal/ferromagnetic hetero-structures, while many spintronics devices prefer smaller damping parameter. Since the spin pumping effect is directly related with the spin dependent interface conductance, we can modify the spin pumping by altering the interface conductance with the nano-oxide layer. We prepared series of Pd/Ni81Fe19 bilayers with different pausing time between Pd and Ni81Fe19 depositions in order to control the interface conductance. The Gilbert damping parameters are determined from the line-width measurements in the ferromagnetic resonance spectra for each pausing time sample. They are 0.0490, 0.0296, 0.0278, and 0.0251 for 0, 6, 30, and 60 s pausing time, respectively. We find that the damping parameter of Pd/Ni81Fe19 is almost recovered to one of the Cu/Ni81Fe19 bilayer with 60 s pausing time, while the static magnetic properties are not noticeably changed.