Coverage-dependent magnetization of 3d transition-metal adatoms on Co(0 0 1) in the submonolayer regime

The electronic structure of 3d transition-metal atoms on face-centered cubic Co(0 0 1) substrate is determined within ab initio density functional calculations in the gradient corrected approach. Calculations are performed for ordered surface configuration with coverage equal to 0.25, 0.5, 0.75 and 1 ML. For Ni and Fe a ferromagnetic coupling with the Co atoms is always obtained independently of the concentration. Moreover the values of the magnetic moments remain similar. For Mn a ferromagnetic coupling is obtained for low-coverage whereas an in-plane antiferromagnetic coupling is found for a complete Mn overlayer on Co(0 0 1). Also, for Sc, Ti, V and Cr a drastic modification of the magnetic map is observed when we go from low-coverage to the monolayer. Cr (Mn) adatoms present antiferromagnetic (ferromagnetic) coupling with Co(0 0 1) for x = 0.25 whereas an in-plane antiferrimagnetic coupling is obtained for x = 1.00.