Spectral density of Barkhusen noise in FINEMET-type materials

Barkhausen noise experiments, performed on different, heat treated FINEMET-type (Fe75Si15NbCu) ribbons, are discussed. The spectral density of the noise, measured under a constant magnetization rate, exhibits a definite change with the nanostructure of the ribbons. Thus mechanical sensitivities (δ) were compared with the Fourier spectra of the samples. It is found that the high and low frequency portions of the spectral density of the noise display a definite correlation with δ. This is similar to the one observed between the full dissipated Barkhausen noise energy of one exciting cycle and the mechanical sensitivity in our previous paper. Our results indicate that the investigation of the spectral density provides a rationale for non-destructive testing during industrial preparation of FINEMET-type materials.