Antiferromagnetic coupling across nonmagnetic transition-metal films alloyed with ferromagnetic elements

Interlayer exchange coupling has been intensively studied for over 30 years and has been successfully incorporated into almost all magnetic thin-film devices. In this study we find that antiferromagnetic interlayer exchange coupling can be achieved across, and improved by, spacer layers containing over 60 at.% of magnetic material. Measurements of sputtered $\mathrm{Fe}$-doped spacer layers with x-ray magnetic circular dichroism reveal that the magnetic atoms in such spacer layers retain a large magnetic moment. The addition of magnetic atoms to the spacer layer is shown to double the coupling strength, leading to the largest-ever-observed antiferromagnetic bilinear coupling strength in magnetic multilayers deposited by magnetron sputtering, which is the industrial technique of choice. Electronic structure calculations in this work predict an experimentally obtained dependence of interlayer exchange coupling on both the magnetic material concentration and the spacer-layer thickness, in contrast with the prevailing understanding of interlayer exchange coupling.