High-frequency permeability of electroplated CoNiFe and CoNiFe-C alloys

We have investigated CoNiFe and CoNiFe-C electrodeposited by pulse reverse plating (PRP) and direct current (DC) techniques. CoNiFe(PRP) films with composition Co_59.4Fe_27.7Ni_12.8 show coercivity of 95 A m^-1 (1.2 Oe) and magnetization saturation flux (μ₀M_s) of 1.8 T. Resistivity of CoNiFe (PRP) is about 24 μΩ cm and permeability remains almost constant μ_r′ ∼475 up to 30 MHz with a quality factor (Q) larger than 10. Additionally, the permeability spectra analysis shows that CoNiFe exhibits a classical eddy current loss at zero bias field and ferromagnetic resonance (FMR) when biased with 0.05 T. Furthermore, a crossover between eddy current and FMR loss is observed for CoNiFe-PRP when baised with 0.05 T. DC and PRP plated CoNiFe-C, which have resistivity and permeability of 85, 38 μΩ cm, μ_r′=165 and 35 with Q>10 up to 320 MHz, respectively, showed only ferromagnetic resonance losses. The ferromagnetic resonance peaks in CoNiFe and CoNiFe-C are broad and resembles a Gaussian distribution of FMR frequencies. The incorporation of C to CoNiFe reduces eddy current loss, but also reduces the FMR frequency.