Surface analysis of ion irradiated amorphous ribbon by GIXD and NEXAFS

Recently a great increase of giant magneto impedance (GMI) ratio due to ion irradiation was found in the amorphous ribbon and intensive research into this mechanism will result in a technological importance in the field of sensor applications. The mechanism of the abrupt increase of GMI ratio by ion irradiation was not identified yet. The samples used in the present study were commercial amorphous ribbons of Co₆₆Fe₄B ₁₅Si₁₅, in the size of 2 mm × 40 mm × 20μm. Various kinds of ions such as N, Ar, and Xe have been irradiated with energy of 70 keV by an ion implanter and an ion dosage was set to 1.0×10 ¹⁶ ion/cm² at a beam flux of 3.7 μA/cm². The grazing incident X-ray diffraction (GIXD) and near edge X-ray absorption fine structure (NEXAFS) experiments have been conducted in order to know the origin of abrupt increase of GMI ratio by ion irradiation. The GMI ratio was increased by about 6 times by an ion irradiation for the 1 MHz measuring frequency, and the change of the GMI ratio by an ion irradiation decreased with an increasing measuring frequency. The creation of crystalline phase and the new phase change were not observed from GIXD and NEXAFS experiments in case of Ar ion irradiation, but the drastic changes of the spectrum in the GIXD and NEXAFS experiment in case of Xe and N show that the crystalline phase and new phase change may affect the enhancement of GMI properties.