(A) study on the barkhausen noise in the ion implanted $Co_{66}Fe_4B_{15}Si_{15}$ amorphous ribbon

Abstract

Recently the great increase of giant magneto impedance (GMI) ratio due to ion irradiation was found in amorphous ribbon and intensive research into this mechanism will result in a technological advance in the field of sensor applications. Earlier studies of irradiation effects on magnetic alloys centered mainly on neutron irradiation of bulk materials. Despite a number of previous studies, the understanding of the neutron irradiation effects on magnetic properties of amorphous and crystalline magnetic materials remains controversial, in part, due to the complex nature of the problem. Generally, the changes of magnetic properties of materials are interpreted in terms of domain wall dynamics. Barkhausen noise (BN) gives insight into the domain wall dynamics because it originates from the irreversible displacement of domain wall which is caused by variation in the wall energy with wall displacement. This study investigates the behavior of BN as observed in the ion irradiated amorphous ribbon as a function of ion dose and ion energy. The behavior of BN is analyzed by means of signal analysis techniques including fast Fourier transform and wavelet transform, and the results are interpreted on the basis of radiation damage theory and domain wall dynamics. The GMI response of the ion irradiated $Co_{66}Fe_4B_{15}Si_{15}$ amorphous ribbon showed quite different behavior respect to the irradiated ion energy, ion dose and the applied driving frequencies range. For ion energy, the drastic increase of GMI was found in the sample irradiated with energy of 100 keV, but a similar size of increase was observed in the sample of 50 keV and 70 keV. So, a direct dependence of ion energy on GMI was not found. On other hand, the GMI was varied according to the ion dose and the driving frequency for ion dose. Maximum increase of GMI was observed in the sample of the maximum ion dose and the linear increase of GMI on ion dose also observed. The parameters of Barkhausen noise incre...