| In the present thesis, we study the change in structural properties induced by ion beam irradiation of Ni/Fe and Co/Cu bilayers using various x-ray scattering techniques. These bilayers exhibit interesting GMR and magnetotransport properties.; We show that an N-step model is useful in simulating any given electron density profile. We test four different interface profile functions in fitting the reflectivity and conclude that the error-function profile best describes our samples. Different types of interfaces are introduced, namely graded and rough interfaces, together with a discussion of their representation and their effect on both specular reflectivity and non-specular x-ray intensity.; We develop a data acquisition and processing method in order to separate the specular and diffuse components of x-ray scattering and to obtain the normalized reflectivity. A computer program in C was developed to calculate the x-ray reflectivity (XRR) and diffuse scattering intensity and to fit the theoretical calculation to the experimental data using a non-linear least-squares fitting method.; By fitting the XRR data of six bilayers of Ni/Fe and Cu/Co of different thicknesses and deposition sequence, the electron density profiles are constructed for different irradiation doses, &phis;. The intermixing at interfaces is found to increase with increasing &phis;. No change in the bulk materials electron density is observed upon irradiation of four single layers of these materials.; A more detailed study is performed on Si/Ni(500A)/Fe(500A) bilayers. From diffuse-scan fits we find that as &phis; increases the interfaces become rougher, more jagged and the height-height correlation length of the roughness decreases. The intermixing can be approximated using the ballistic model of ion mixing.; Using high-angle x-ray diffraction (XRD) measurements, the samples are found to be polycrystalline with a strong texture of fcc Ni(111) and bcc Fe(101) parallel to the substrate surface. Both plane-view and cross-sectional transmission electron microscopy (TEM, XTEM) images show that in-plane and out-of-plane grain sizes increase with &phis;, in good agreement with out-of-plane grain sizes calculated from Bragg peaks. The high-angle x-ray Bragg peak positions agree well with selected-area electron diffraction (SAED) rings. The iron oxide parameters obtained from XTEM and SAED patterns agree well with XRR results. |
