Electromagnetic and microwave properties of NiFe/NiFeO multilayer thin films

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 (fr). 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 fr rose from 1.07 to 2.85 GHz, and the saturation magnetization (4πMs) 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 (αeff) increases to 0.078 for t = 6 nm.