Effect of Inserting a Pt Layer into a Perpendicularly Magnetized Co/Ni Multilayered Film in Terms of Current-Induced Domain Wall Motion

The effect of inserting a Pt layer into a Co/Ni multilayered film with a perpendicular magnetization in terms of current-induced magnetic domain wall (DW) motion has been investigated. We found that the current density required to obtain DW motion was approximately 1.9 times greater in Co/Ni/Pt wire than in Co/Ni wire, in spite of the Co/Ni and Co/Ni/Pt multilayered films having almost identical magnetic properties. Estimation of spin polarization from measurements of DW velocity indicated that the decreased spin polarization caused by insertion of the Pt layers accounts for the increased current density required for DW motion in Co/Ni/Pt wire.