Magneto-Optical Kerr Rotation and Sublattice Magnetic Moments in RE-Co Sputtered Films

Temperature and compositional dependences of magnetization rare earth (RE=Gd, Tb, Dy, Nd)-Co sputtered films are analysed using the mean field theory, and the sublattice magnetic moments M Co and M RE are calculated as a function of composition. The Kerr rotation angle θ K is measured at room temperature in a range of optical wavelenghs from 400 nm to 670 nm. The compositional variation of θ K can be described by a model in which two sublattice magnetic moments contribute to θ K independent of each other in an additive or a subtractive fashion: K (Co) M Co ± K (RE) M RE . The value of K (Co) coincides approximately with that of a pure Co film, whereas K (RE) depends on the RE element significantly.