Effect of atomic relaxations on magnetic properties of adatoms and small clusters

Performing ab initio and tight-binding calculations we demonstrate the effect of atomic relaxations on the magnetic properties of Co adatoms and Co clusters on the Cu(001) surface. Atomic relaxations decrease the spin and orbital magnetic moments and drastically affect the magnetic anisotropy of the Co adatom. We show that due to relaxations the in-plane magnetization of the Co adatom is stabilized.