Kerr rotation enhancement and correlation between perpendicular anisotropy and Kerr effect in PtCu(Al,Ag)/Co multilayers

Abstract

The effects of doping Cu, Al, and Ag in Pt spacer layers on the perpendicular anisotropy Ku and the polar Kerr rotation Θk in the wavelength range of 400–800 nm have been investigated for sputtered 0.8 nm Pt/0.3 nm Co multilayers. Ku and Θk measured below 633 nm decrease with the increase of the concentrations of Cu, Al, and Ag in the Pt spacer layers. It is found that the variation of Ku and Θk with the doping concentrations follows a quadratic equation of Ku=aΘ2k+b (a, b are constants here). This suggests that both Ku and Θk originate from a common micromechanism, i.e., spin-orbit coupling. An obvious enhancement in the peak of the polar Kerr rotation appears at 770 nm for Cu and Ag dopings and at 680 nm for Al doping. Moreover, the polar Kerr rotation Θk* at this enhanced peak shows an oscillation behavior with the increasing doping concentrations in the Pt spacer layers.