No abstract

The MO spectra of GMR structures with capping layers, Si/SiO2/bottom electrode/TbFeCo (9 nm)/Cu (4 nm)/ Co (0.1 nm)/Pt (1.1 nm)/(Pt (1.1 nm)/Co (6 nm)!4)/cap (cap = Ta, Au, Pt (3 nm)), were studied. We found that the optical constants and Kerr spectra exhibited different behaviors for all samples. The differences in the optical constants of these samples were analyzed by means of optical simulation. The MO spectrum is discussed in terms of simulation carried out by the virtual optical constant method for (PtCo)/cap (cap = Ta, Au, Pt (3 nm)).

The magnetic behaviors and the microstructures of the two Co layers in the Ni buffered Co 55 Å/Cu 35 Å/Co 55 Å sandwich were investigated by a vibrating sample magnetometer and high resolution transmission electron microscope. It was found that the structural quality of the two cobalt layers depends on their different `buffer' layers. The lower cobalt layer induced by the nickel layer formed high quality face-centered cubic (fcc) structure, while the upper cobalt layer grown upon the copper matrix produced only random-oriented fcc-Co structure. The different crystalline states between the two Co layers resulted in their different magnetic behaviors through the magnetostatic effect, which made it possible to achieve a maximum anti-aligned state and finally enhanced the giant magnetoresistance (GMR) effect in the Co/Cu/Co sandwich.