MAGNETIC ANISOTROPIES IN ULTRATHIN FCC FE(001) FILMS GROWN ON CU(001) SUBSTRATES

Brillouin light scattering and ferromagnetic resonance have been used to measure the magnetic-field dependence of the magnon frequency at room temperature for three-monolayer-thick films of fcc Fe(001) grown by means of molecular-beam epitaxy on Cu(001) substrates. These films exhibit a strong uniaxial magnetic anisotropy which causes the magnetization to be oriented perpendicular to the film plane in zero applied field. Four specimens were grown on copper substrates prepared using a chemical polishing technique which avoided the use of abrasives: This treatment greatly reduced the density of etch pits on the copper surface. The uniaxial anisotropies found for these specimens were very consistent and comparable to that previously measured for the best film grown on a mechanically polished copper substrate. There is evidence that substrate smoothness is improved and, hence, that the uniaxial anisotropy is increased when the substrate is covered with a few monolayers of epitaxial copper before the iron films are grown.