The effect of Pd doped in Ru layer on the interlayer coupling in Co/RuPd multilayers

2.0nmCo/tnmRu_1-xPd_x multilayers with x=0, 0.05, 0.08, 0.24, 0.39 and 0.48 were prepared by magnetron sputtering. The spacer layer thickness of both Ru (before doping Pd) and RuPd (after doping Pd) varies from 0.2nm to 1.6nm. Two effects have been investigated: (1) the dependence of the interlayer coupling on the thickness of Ru_1-xPd_x as a function of x and (2) the dependence of the interlayer coupling on Pd doping density, x, as a function of thickness of Ru_1-xPd_x. Our results indicate that the interlayer coupling is strongly dependent on the doping density and the spacer layer thickness. The saturation field H_s increases when very low concentration of Pd doped in the Ru layers and a suitable spacer thickness are adopted.