Ferromagnetic Resonance Study on Si/NiO/NiFe Films

Motivated by the wide application of the antiferromagnetic/ferromagnetic (FM) bilayer structures in high-frequency microwave magnetic devices, the Si/NiO/Ni₈₁Fe₁₉ films with different orientations of NiO buffer layer are deposited by magnetron sputtering technology. The phase, microstructure, hysteresis loop, and angular dependence of FM resonance (FMR) linewidth are investigated by X-ray diffractometer, field-emission scanning electron microscope, atomic force microscope, vibrating sample magnetometer, and electron spin resonance spectrometer, respectively. The Si/NiO(220) film has much smaller grain size than that of Si/NiO(200) film, which is beneficial to grow a high quality NiFe film on Si/NiO(220)/NiFe bilayer structures. The hysteresis loop of Si/NiO(220)/NiFe films shows an obvious exchange bias and a relatively smaller coercivity. The FMR linewidth (ΔH) of Si/NiO(220)/NiFe films is much smaller than that of Si/NiO(200)/NiFe films, which is caused by the different structural properties and morphologies of the NiO buffer layer. The Landé g factors and effective damping parameters α_eff are also discussed.