Frequency dependence of coercivity in nickel and Co–Fe–B thin film for DC to 100 kHz region

Abstract

To investigate magnetization process in the intermediate frequency region, the frequency dependences of coercivities in Ni and Co-Fe-B thin films were determined by anisotropic magnetoresistance measurements up to ~160 kHz. In the low-frequency region (< 5 kHz) the coercivity of Co-Fe-B was lower than that of Ni. However, the increasing rate of the coercivity in Ni was lower than that in Co-Fe-B. Consequently, above 19 kHz, the coercivity of Ni was lower than one of Co-Fe-B. Considering the basic material properties, better soft magnetic properties of Ni compared with Co-Fe-B should arise from the higher Walker breakdown field. This difference was mainly due to the Gilbert damping constant.