Selective writing of sub-μm² domain in spin valve strip with current coincident scheme

Cooperative nucleation of sub-μm² domains has been performed for a spin valve strip (0.4 μm width) of NiFe/Co/Cu/Co overlaid with orthogonal two-layer conductors (write and assist conductors). The current induced MR change due to the write current I_w markedly increases with the additional assist current I_a. Threshold value of I_w required for domain nucleation was decreased from 15 mA/μm to 9 mA/μm by the application of I_a with an amplitude of 10 mA/μm, which confirms selective writing with the current coincident scheme. The cooperative effect disappears, when the phase difference between I_w and I_a becomes larger than the pulse width of 30 ns. Which can be associated with the fast relaxation time of the magnetization process in the sub-μm² region.