Magnetic nanostructures on the fcc Fe/Cu(100) surface

We present systematic ab initio calculations for the magnetic moments of $3d$ and $4d$ transition-metal impurities on the high-moment ferromagnetic phase of fcc Fe/Cu(100) surface. We find that on this substrate the moments of the impurities are in general larger than on bcc Fe. Furthermore the transition from antiferromagnetic to ferromagnetic coupling occurs at smaller valencies. A very subtle behavior is found for Ru nanostructures, which show ferromagnetic coupling for adatoms and linear chains, but antiferromagnetic coupling for larger islands and monolayers.