The direct current and microwave resistivities arising from domain wall scattering for Ni and Co films

The frequency dependences of surface resistances of ferromagnetic films were measured by a four-point van der Pauw method and a microwave micro-strip method, respectively, to evaluate the direct current (DC) and radio frequency (RF) resistivities arising from domain wall scattering. We observed that the magnetoresistances (MR) in nickel and cobalt films change manifestly as the current conducts from parallel (CIW) to perpendicular (CPW) to the domain walls, which were inspected by a magnetic force microscopy (MFM). The DC resistivity for currents conducting parallel to domain walls (CIW) is significantly smaller than that of the perpendicular (CPW) case. Whereas indistinguishable changes in CIW and CPW conductions were observed for signals increase to microwave frequency where films are configured in T-microstrips.