Stack Structure Dependence of Co/Ni Multilayer for Current-Induced Domain Wall Motion

• Published in: Applied physics express 2010-11, Vol.3 (11), p.113002-113002-3
• Main Authors: Fukami, Shunsuke, Suzuki, Tetsuhiro, Tanigawa, Hironobu, Ohshima, Norikazu, Ishiwata, Nobuyuki
• Format: Article
• Language: English
• ISSN: 1882-0778; 1882-0786
• DOI: 10.1143/APEX.3.113002

We developed a film stack structure of Co/Ni with perpendicular magnetic anisotropy (PMA), which is suitable for current-induced domain wall (DW) motion. A Ta/Pt underlayer effectively provided a sufficiently large PMA to achieve the DW motion driven by a small current. The critical current density ($\aki j_{\text{c}}$) had a minimum value at a Pt underlayer thickness ($t_{\text{UL}}$) of 2.4 nm and was insensitive to cap layer thickness ($t_{\text{cap}}$). The de pendence of $j_{\text{c}}$ on $t_{\text{UL}}$ and $t_{\text{cap}}$ can be accounted for in terms of the effective spin polarization.