Long-range electronic interactions between adatoms on transition metal surfaces

Ab initio calculations of surface-state mediated interactions between Cu adatoms on transition metal surfaces are presented. We concentrate on Co/Cu(1 1 1) and Co(0 0 0 1) substrates and compare results with our calculations for Cu(1 1 1). Our studies show that surface states of Co/Cu(1 1 1) and Co(0 0 0 1) are spin-polarized. We reveal that long-range interactions between adatoms are mainly determined by sp-majority states. In contrast to Cu(1 1 1) and Co/Cu(1 1 1), the interaction between adatoms on Co(0 0 0 1) is strongly suppressed at large adsorbate separations.