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We report current-induced domain wall motion (CIDWM) in Ta\Co20Fe60B20\MgO nanowires. Domain walls are observed to move against the electron flow when no magnetic field is applied, while a field along the nanowires strongly affects the domain wall motion direction and velocity. A symmetric effect is observed for up-down and down-up domain walls. This indicates the presence of right-handed domain walls, due to a Dzyaloshinskii-Moriya interaction (DMI) with a DMI coefficient D=+ 0.06 mJ/m2. The positive DMI coefficient is interpreted to be a consequence of boron diffusion into the tantalum buffer layer during annealing. In a Pt\Co68Fe22B10\MgO nanowire CIDWM along the electron flow was observed, corroborating this interpretation. The experimental results are compared to 1D-model simulations including the effects of pinning. This advanced modelling allows us to reproduce the experiment outcomes and reliably extract a spin-Hall angle {\theta} SH=-0.11 for Ta in the nanowires, showing the importance of an analysis that goes beyond the currently used model for perfect nanowires.
Publication date: 
12 Sep 2014

R Lo Conte, E Martinez, A Hrabec, A Lamperti, T Schulz, L Nasi, L Lazzarini, F Maccherozzi, SS Dhesi, B Ocker, CH Marrows, TA Moore, M Kläui

Biblio References: 
arXiv preprint arXiv:1409.3753