Some interesting behaviors observed in nanostructured magnetic multilayers with alloy spacers

Abstract

This paper summarizes our recent experimental results on investigating magnetic multilayers with alloy spacers. The main results are: the doping of Cu, Al, and Ag into a Pt layer and Cu into a Pd layer result in the polar Kerr rotation enhancement and oscillation with the increasing doping density in PtCu(Al, Ag)/Co and PdCu/Co multilayers. In the dilute PtNi alloy/Co multilayers, the Curie temperature of the multilayers increases monotonically with increasing of the Ni concentration in the Pt spacer layer and the saturation magnetization shows an oscillation-like behavior with the increase of the Ni concentration in the Pt spacer at room temperature. The temperature dependence of the saturation magnetization and effective perpendicular anisotropy in the dilute PtNi alloy/Co multilayers also shows some interesting results, i.e. the broad peaks of the magnetization and anisotropy appear nearly at the same temperature and both peak values show a simultaneous oscillation-like behavior as the Ni concentration increases. Within the framework of quantum confinement size, the oscillation of the polar Kerr rotation has been discussed. On the basis of the RKKY interaction we have calculated the exchange coupling between Co-Ni and Ni-Ni atoms and found that the total coupling energy is responsible for the elevation of the Curie temperature for the samples with Ni doping. The calculation also indicates that the oscillations of the magnetization may arise from Fermi vector reduction. Using the mean field theory we have discussed the temperature dependence of the magnetization and anisotropy in the dilute PtNi alloy/Co multilayers.