Concentration dependent spin-flip energies for alloyed surface magnets

Single and double spin-flip energies are calculated for n layers of homogen eously disordered FecCo1-c on Cu(100) with n varying between three and six. It is found that these spin-flip energies describe quite accurately the ty pe of most favourable magnetic coupling between the magnetic layers and als o give a rather detailed picture for the occurrence of certain magnetic con figurations. A phase diagram of ferromagnetic Versus antiferromagnetic coup ling with respect to the number of layers and Fe concentration turns out to be closely related to the phase diagram of the reorientation transition in this system.