Rotation angle of magneto-optical Kerr effect with different capping layer on CoFe film

To understand the influence of rotation angle in magneto-optical effect between conductor and insulator capping layer, we fabricate Co₅₀Fe₅₀/Ta, Co₅₀Fe₅₀/MgO, and Co₅₀Fe₅₀/SiN_x bilayers with fixed CoFe thickness and modulated capping layer to systematically study the dependence on the thickness and material of capping layer. We also changed the CoFe thickness with fixed Ta. The switching characteristics were studied using longitudinal magneto-optic Kerr effect (LMOKE) techniques. The hysteresis loops (MH loops) and the coercivity measured by AGM are independent of the capping layer. Our data show the Kerr rotation angle as a function of capping layer thickness. Based on our calculations, the effective rotation angle changes with different capping material. The phenomenon of the increasing Kerr rotation angle is known to be dependent on the dielectric constant and refractive index of the capping layer. A comparison between the rotation angle in LMOKE and the material property has led to a better understanding of the relationship of light refracted in Ta, MgO and SiN_x.