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摘要
We report a detailed study of the structural and ferromagnetic resonance properties of spinel nickel ferrite (NFO) films, grown on (100)-oriented cubic MgAl2O4 substrates by direct liquid injection chemical vapor deposition (DLI-CVD) technique. Three different compositions of NFO films (NixFe3-xO4 where x=1, 0.8, 0.6) deposited at optimized growth temperature of 600 degrees C are characterized using X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Vibrating Sample Magnetometry (VSM), and broadband ferromagnetic resonance (FMR) techniques. XRD confirms the growth of epitaxial, single crystalline NixFe3-xO4 films. The out-of-plane lattice constant (c) obtained for Ni0.8Fe2.2O4 film is slightly higher than the bulk value (0.833 nm), indicating only partial strain relaxation whereas for the other two compositions (x=1 and x=0.6) films exhibit complete relaxation. The in-plane and out-of-plane FMR linewidths measurements at 10 GHz give the lowest values of 458 Oe and 98 Oe, respectively, for Ni0.8Fe2.2O4 film as compared to the other two compositions. A comprehensive frequency (5-40 GHz) and temperature (10-300 K) dependent FMR study of the Ni0.8Fe2.2O4 sample for both in-lane and out-of plane configurations reveals two magnon scattering (TMS) as the dominant in-plane relaxation mechanism. It is observed that the TMS contribution to the FMR linewidth scales with the saturation magnetization M-s. In-plane angle-dependent FMR measurements performed on the same sample show that the ferromagnetic resonance field (H-res) and the FMR linewidth (Delta H) have a four-fold symmetry that is consistent with the crystal symmetry of the spinel. SEM measurements show formation of pyramid like microstructures at the surface of the Ni0.8Fe2.2O4 sample, which can explain the observed four-fold symmetry of the FMR linewidth.
- 出版日期2016-11-1
- 单位中国林业科学研究院
