The influence of the surface topography on the magnetization dynamics in soft magnetic thin films

Abstract

In this work we study the influence of surface roughness on the magnetization dynamics of soft magnetic nanocrystalline Fe–Zr–N thin films deposited (under identical conditions) onto a Si oxide, a thin polymer layer, and a thin Cu layer. The substrate temperature during deposition was approximately −25°C ensuring a nanocrystalline state. The demagnetizing factors due to sample roughness were calculated based on atomic force microscopy (AFM) analysis of the surface topography. A clear correlation between sample roughness and the width of the high-frequency response is observed. The local random demagnetizing field created by the nanocrystalline structure and the surface topography is responsible for the positive shift of the ferromagnetic resonance frequency. In addition, a pronounced effect of line broadening is induced by the surface topography at large wavelengths. Finally, we show a good agreement between the values of the average demagnetizing field 4πNMS as calculated from the AFM scans, and the values calculated from the frequency-dependent complex permeability measurements.

Research on double resonance peaks and abnormal frequency shift in permeability spectra of annealed FeCoB films

“…Additionally, there are other experimental results which support our conclusion: (1) In Fig. 6 of Craus et al, [3], an obvious positive shift of resonance peak was reported. It is reasonable that the broadening and the shift in the permeability spectra can be attributed to the stray fields mainly coming from the inferior surface topography.…”

“…Up to now, there are several published experimental results of the multiple resonance peaks in the ferromagnetic films [3][4][5][6], but the nature of the multiple resonance peaks is seldom discussed and remains as a puzzle. Hoffmann's ripple theory can be successfully used to explain slight positive frequency-shift of permeability [7,8]; however, it falls short of its ability in analyzing the existence of the multiple resonance peaks.…”

“…In order to improve the performance and enlarge the applicability of the materials, some properties, other than the high saturation magnetization 4pM S and suitable anisotropy H k [1,2], are needed for the design of the materials. The position and width of the resonance peak in permeability spectra should be artificially adjustable for the different working frequencies [3]. The introduction of multiple resonance peaks is a feasible approach to modify the line-width and extrinsic parameters [4,5].…”

Electromagnetic and microwave properties of NiFe/NiFeO multilayer thin films

“…The greater the thickness of the NiFeO layer, the greater the effective damping coefficient. The addition of NiFeO introduces more defects and impurities in the film, and the inhomogeneity of the [NiFe/NiFeO] 10 multilayer films specifically contributes to the increase of a eff [30]. A relatively large …”

Experimental study of the magnetic characteristics of nanocrystalline thin films: the role of edge effects

“…However, there is a number of factors that can lead to the formation of spatial variations of magnetic characteristics over the film area. Dispersion of the magnetic anisotropy, magnetization saturation, and other magnetic characteristics reduce the magnetic susceptibility [7,8] and enhance the magnetic noise in a film. It was found that the magnetic noise caused by the spatial dispersion of the magnetic characteristics is the key factor that limits the sensitivity of the magnetic field sensors based on a thin magnetic film [9][10][11].…”