Magnetic anisotropy variation of Fe single atom on Ti/Al(001) surface by the change of Ti-Al surface phase

Using density functional theory based ab initio calculations, we investigated the effects of Ti/Al(001) surface phase variation on the Fe adatom magnetism. The symmetry of the in-plane magnetic anisotropy of the Fe adatomcorresponded to the symmetry of the Ti and Al atomic configurations on the top surface. When B2 or L1 ₂ structures of Ti and Al atoms were formed on the surface, the energy barriersfor the Fe in-plane magnetization rotations were smaller than the case of the bare Al(001) surface. The out-of-plane magnetization of Fe adatoms were induced only on the Al-terminated substrates while the Fe on the Ti-appearing surface had its magnetic easy axis in the in-plane directions. The magnetic anisotropy energy magnitude was, on the other hand, largely determined by the underlayer composition of Ti-Al alloy. The decomposed 3d-electron density of states showed that the 3d _xy and 3d _z2 orbitals of Fe adatoms provide the main contribution to the variation of the magnetic anisotropy energy.