Abstract
In this thesis, we studied the effect of capping layers on the CoFeB Gilbert damping constant, which was an important factor for the critical current density of spin-transfer. To investigate the dynamic magnetic property of CoFeB films, the ferromagnetic resonance technique (FMR) was carried out and the angular dependence of FMR was numerically calculated to obtain the Gilbert damping constant. The different metals of Cu, Ta and Ag inserted into the Co72Fe8B20/Ta interface were prepared by ion beam deposition to study the capping effect on the effective damping constant. It is found that there are two sources, the intermixing effect and the spin-pumping effect, to enhance the effective damping constant, especially within the thinner ferromagnetic film. Besides, it is also observed that the 2.5 nm Co60Fe20B20/Ta (0.012) possess the lower effective damping constant than 2.5 nm Co72Fe8B20/Ta (0.016). Finally, the lower effective damping constant of Co60Fe20B20/Cu/Ta is used to study the annealing effect on magnetic properties including of Ms,, HC, and HK. It is also found that magnetic properties during the annealing are strongly affected by the boron diffusion.