Spin engineering: Direct determination of the Ruderman-Kittel-Kasuya-Yosida far-field range function in ruthenium

Oscillations in both ferromagnetic and antiferromagnetic indirect exchange coupling through Ru are directly measured. Ferromagnetic coupling is determined by spin engineering multilayered structures comprised of trilayers of ${\mathrm{Ni}}_{80}$${\mathrm{Co}}_{20}$/Ru/${\mathrm{Ni}}_{80}$${\mathrm{Co}}_{20}$ in which one of the ${\mathrm{Ni}}_{80}$${\mathrm{Co}}_{20}$ layers is strongly antiferromagnetically pinned to a Co layer. Oscillations in antiferromagnetic exchange coupling are measured in companion ${\mathrm{Ni}}_{80}$${\mathrm{Cu}}_{20}$/Ru multilayers. The dependence of the exchange coupling strength on Ru thickness is well described by the Ruderman-Kittel-Kasuya-Yosida far-field range function, providing a direct measurement of this function through a transition metal.