الملخص الإنجليزي
For information storage memory application, there is a continuous development of materials for low power, good thermal stability and scalability without degradation of the device performance. In this study, CoFeB alloys and (Co/Pd) multilayers have been investigated using magnetometry measurements and magnetic force microscopy. For the deposited samples, a strong dependence of the magnetization orientation on CoFeB thickness was observed. An improvement of the anisotropy energy of CoFeB is possible by increasing the interface effect through adding a very thin Ta layer. Magnetization reversal has been study for annealing temperatures of 200 °C and 240 °C. For (Co/Pd)xn multilayers, it was observed that the magnetization reversal mechanism and magnetic domains size dependent on the number of repeats N. Magnetic domain patterns evolution with magnetic field will also be discussed. From Magnetic domains simulation using Landau-lifshitz-Gilbert formalism an approximate evaluation of (Co/Pd)x8 magnetic properties was obtained
Our results showed that there was a transition from out-of-plane to in-plane as the thickness increased from 1.2nm to 1.6nm. The study showed that Perpendicular Magnetic Anisotropy (PMA) was critical to 1.2nm single layer thickness at 200 °C and 2.6nm total thickness with Ta lamination for both 200 °C and 240 °C. For better PMA, (Co/Pd)xN multilayers was investigated. The study showed that the magnetization reversal mechanism and magnetic domains size are closely dependent on the number of repeats N. Magnetic domain patterns evolution with magnetic field was discussed. Three regions of magnetic domains were clearly distinguished from MFM images. The third region (moderate contrast) could be due to a non-uniformity of Co thickness along the film growth axis. This may cause a difference of the Pd effective thickness and consequently could cause an "antiferromagnetic coupling". As the field increased, the 15 repeats (Co/Pd) were more stable. For (Co/Pd)x8, there was a reduction of down domains area leading to large up domains area as the magnetic field was increased. Micromagnetic simulation was conducted to study magnetic domains for (Co/Pd)x8 multilayers. By compering, the simulated and experimental results, Ms of 600 A/m and Ku of 3x10 J/m2 were obtained.
