Proximity effects of overlayers on surface magnetism: Al adsorbed on Fe(001)

Magnetic moments and magnetic hyperfine fields at the Fe(001) surface covered by a simple metal, Al, have been calculated employing the full potential linearized augmented plane wave (FLAPW) method. From total energy calculations the Al-Fe bond-length is found to be 4.53 au which is smaller than those of some bulk Al-Fe compounds by about 4%. The magnetic moment (1.38μ_B) is greatly reduced compared to those of clean Fe(001) and bulk Fe, by 54% and 38% respectively. From the energy band structure and density of states this reduction appears to come from the hybridization of Al-s, p and Fe-d electrons. As regards the Fermi contact hyperfine interaction, the Al-s, p electrons promote the conduction electrons of the interface Fe to have a negative indirect polarization (-46 kG). As result of this negative contribution, the magnitude of the magnetic hyperfine field (-235 kG) at the interface Fe becomes comparable to that (-252 kG) of clean Fe(001) despite the large reduction of magnetic moment.