Determination of effective field induced by spin-orbit torque using magnetic domain wall creep in Pt/Co structure.

We investigated the effect of electric current on the magnetic-field-driven magnetic domain wall (DW) creep velocity in ultrathin Co with perpendicular magnetic anisotropy deposited on a Pt underlayer. The DW velocity was considerably modulated by the current, and its field dependence deviated from the scaling law with the critical exponent of 1/4, which is generally valid in ferromagnetic metals. This characteristic feature of the DW motion can be explained by considering the perpendicular effective field generated by spin-orbit torque at the Pt/Co interface. From the relation between the injected current and the modified creep velocity, the determination of the effective field was demonstrated. [ABSTRACT FROM AUTHOR]