Spin pumping and interlayer exchange coupling through palladium

Abstract: The magnetic behaviour of ultrathin ferromagnetic films deposited on substrates is strongly affected by the properties of the substrate. We investigate the spin pumping rate, interlayer exchange coupling and dynamic exchange coupling between ultrathin ferromagnetic films through palladium, a non-magnetic substrate that displays strong Stoner enhancement. We find that the interlayer exchange coupling, both in the static and dynamic versions, is qualitatively affected by the substrate's Stoner enhancement. For instance, the oscillatory behavior that is a hallmark property of the RKKY exchange coupling is strongly suppressed by Stoner enhancement. Although the spin pumping rate of ferromagnetic films atop palladium is only mildly changed by Stoner enhancement the change is large enough to be detected experimentally. The qualitative aspects of our results for palladium are expected to remain valid for any non-magnetic substrate where Coulomb repulsion is large.