Magneto-optical and optical properties of Pt/Co GMR films with capping layer

As a light modulating device used in high resolution magneto-optical spatial light modulator (MO-SLM), giant magneto resistance (GMR) devises driven by spin-injection is promising. In this paper, we report on optical and magneto-optical (MO) properties of GMR films, Si/SiO₂/bottom electrode/TbFeCo (9 nm)/Cu (4 nm)/(Pt/Co (6 nm))/X (X = Ta, Au, Pt (3 nm)). Kerr rotation spectra of those films with Ta, Au, Pt capping layer ranging between 260 – 700 nm have features similar to those of Pt/Co multilayers reported previously. However, peak positions and rotation angles are slightly different; peak positions of Ta, Au, and Pt are 4.1, 4.3 and 3.8 eV, respectively, and maximum Kerr rotations are 0.35, 0.25 and 0.23°, respectively. Optical constants measured by ellipsometry revealed that those values were changed due to the capping layers with a thickness of 3 nm. These results indicate that the non-magnetic layers should be mentioned as well as the magnetic layers to design MO properties of the light modulating devices for MO-SLM.