Low field microwave absorption and magnetization process in CoFeNi electroplated wires

Ferromagnetic resonance (FMR), Ferromagnetic antirresonance (FMAR) and low field magnetoimpedance (MI) are the characteristic features of high frequency losses in applied fields. While some results on FMR and FMAR in CoFeNi electroplated wires were reported earlier, here we present microwave absorption in CuBe wires electroplated by 1\,$\mu$m FeCoNi magnetic layer at very low fields. These data are comparatively analysed together with longitudinal hysteresis loops in order to reveal the correlation between power absorption and magnetization processes. Microwave studies are made by using the cavity perturbation method at 9.65\,GHz for a DC field parallel to the sample axis, and with microwave magnetic field $h_{\rm rf}$ parallel or perpendicular to the wire axis. Two peaks have been observed in all samples, one is due to FMR, and the other is, at very low fields, related to MI. The MI peaks represent minima in power absorption. By comparing with the hysteresis loop we remark the close correspondence between the MI phenomena in the axial mode and the concomitant magnetization process.