Magnetic Properties of Compositionally Modulated Fe/Al Films

Fe/Al compositionally modulated multilayer films were prepared at a low argon pressure of 2 mTorr by double-target dc magnetron sputtering. The low argon pressure resulted in formation of films with minute grain sizes and a low H
_c
. For a constant Al layer thickness of 8 Å, the alloy phase at the interfaces of the Fe/Al layers has a substantial effect on the apparent measured properties of films with an Fe/Al layer thickness ratio of less than 3, resulting in a decreased saturation magnetization with decreasing Fe/Al thickness ratio. At higher Fe/Al thickness ratios, however, the saturation magnetization remained nearly constant. The lowest H
c
was obtained at an Fe/Al thickness ratio of around 3. Films with the optimum preparation parameters of Fe/Al thickness ratio=3 and modulation wavelength=43 Å exhibited the following properties: H
_c
=0.625 Oe, M
_s
=1285 emu/cm
³
, ρ=60 μΩ-cm.