Contribution to the Study of Magnetic Properties of Fe-Zr-Nb-B based nanocrystalline Ribbons and Thin Films

The characterization of structural and magnetic properties of soft amorphous and nanocrystalline Fe-Zr-Nb-B based alloy in the form of ribbons and thin films is presented and discussed in this work. Detailed study of amorphous and nanocrystalline phase of Fe84Nb3.5Zr3.5B8Cu1 ribbons has been carried out using differential scanning calorimetry (DSC) , Thermal gravimetric analysis (TGA), X-ray diffraction (XRD) measurements and Mössbauer spectroscopy. Experimental determination of anisotropy field distribution for nanocrystallline Fe84Nb3.5Zr3.5B8Cu1 ribbons is also presented and discussed in order to have a better idea of effective anisotropy of the system. Magneto transport properties of ribbons were studied by giant magneto impedance measurements. Also discussed is the possible limitation of applicability of random anisotropy model for optimally crystallized soft magnetic materials by presenting a grain size and volume fraction dependence of coercive field applied for the case of a Fe-Co alloy system. Thin film samples were prepared using ion beam sputtering and RF sputtering method using amorphous Fe84Nb3.5Zr3.5B8Cu1 ribbons as target material. Complementary information on the structural properties of amorphous and nanocrystalline thin films was obtained using X-ray reflectivity (XRR), grazing incidence X-ray analysis and atomic force microscopy. Magnetic properties of ribbons and thin film samples were studied using standard hysteresis measurements, vibration sample magnetometer and alternating field gradient magnetometer. Ferromagnetic resonance studies done on as deposited thin film samples are also discussed.