الملخص الإنجليزي
ABSTRACT
The primary aim of the present research was to control the growth of Co/Al and Co/Cu magnetic multilayers. Multilayers have been prepared by computer interfaced DC magnetron sputtering system. The rate of deposition of the individual layers of Co, Cu and Al has been determined from grazing angles X-ray diffraction (GXRD)
spectra. GXRD results confirmed the successful growth of multilayered structure. One of the objectives of this work was to investigate the effect of the computer interfaced system in improving the bilayer period and interfacial roughness of Co/Al multilayers. In addition the effect of changes in deposition pressure and variation in
the thickness of the layers were tested. It was found that, after the system computer interfaced, the samples produced the most intense Bragg peaks of order of 2.5 compared with the multilayers produced before the interfacing of the system. This is a possible indicataion of improved reflectivity from these samples, Hence the appearance of higher order Bragg peaks. Besides the appearance of higher order anca CE Bragg peaks, it has also been observed that the F.W.H.M of these peaks were thinner compared to the initial Bragg peaks that appeared in the earlier multilayers that were produced manually (before the computer interfaced magnetron sputtering system). The application of simulations to the data allowed the approximation of the total and
individual roughness (rms) of the multilayers. Magnetic and electronic properties were carried out by vibrating sample magnetometer (VSM) and four-point probe (FPP), respectively. The maximum magnetoresistance rate (MR) was found to be 2.9% for multilayers. Also, a consequent antiferromagnetic coupling was observed
for optimal Cu thickness. However, the magnitude of MR remains small relative to that reported in the literature. The existence of high interfacial roughness combined to the existence of pin holes with Cu layers, may be the origin of the suppression of antiferromagnetic coupling and limited magnetoresistive effect. The annealing effect
of Co/Cu MLs was also investigated in order to identify the spin dependent scattering WS centres responsible for the MR effect. The results suggest that the main spin dependent scattering centres are located at the Co-Cu interfaces, suggesting a high interfacial spin diffusion asymmetry coefficient a=pu/pt as compared to that of the
