Magnetization of Ni-Si, Co-Si, and Fe-Si layered systems

Magnetization measurements have been performed, using a SQUID magnetometer, on multilayered X-Si films where X is Fe, Co, or Ni. The samples were produced by dc sputtering with the thickness of the Si layers fixed at a value between 30 and 70 Å and the thickness of the X layers varying from 8 to 30 Å. These nominal preparation thicknesses were verified by x-ray diffraction studies. We find that at 5 K the saturation magnetization decreases rapidly with decreasing thickness with a loss of ferromagnetism by layer thicknesses 8 and 14 Å for Fe and Co, respectively. A Ni-Si sample with a Ni thickness of 30 Å was not ferromagnetic. Comparison of measurements made with the applied field parallel and perpendicular to the layers indicates no magnetic aniostropy other than the expected shape anisotropy. Our data are compared with data by Wong and co-workers for Fe-V and data by Kazama and co-workers for amorphous Fe(C)-Si.