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.