Electromagnetic and microwave properties of NiFe/NiFeO multilayer thin films

Abstract

In this work, [NiFe/NiFeO]10 multilayer thin films were fabricated by magnetron sputtering. The microwave and electromagnetic properties were investigated for different thicknesses, t, of the NiFeO layer (t = 0–6 nm) while the thickness of the NiFe was maintained at 8 nm in every cycle. A clear in-plane uniaxial anisotropy field was induced by an external magnetic field. The in-plane uniaxial anisotropy can be adjusted by tailoring the thickness of the NiFeO layer. When t = 0 nm, the NiFe monolayer, which has a thickness of 80 nm, showed low resistivity (ρ) and ferromagnetic resonance frequency (f r ). By increasing the t from 0 to 6 nm, the ρ of the [NiFe/NiFeO]10 films exhibited a significant monotonic increase (from 111.2 to 268.8 μΩ cm), the f r rose from 1.07 to 2.85 GHz, and the saturation magnetization (4πM s ) was decreased from 12.7 to 10.8 kG. The real part (μ′) of the complex permeability is larger than 100 in the range 0.2–1.9 GHz and the damping coefficient (α eff ) increases to 0.078 for t = 6 nm.