Yk. Kim et M. Oliveria, MAGNETIC-PROPERTIES OF SPUTTERED FE THIN-FILMS - PROCESSING AND THICKNESS DEPENDENCE, Journal of applied physics, 74(2), 1993, pp. 1233-1241
The microstructure and magnetic properties of polycrystalline Fe films
with thicknesses of 200-1000 angstrom have been investigated. The fil
ms were prepared by rf sputtering onto SiO2 substrates. The investigat
ion was prompted by the lack of data on sputtered Fe films in this thi
ckness regime as well as disagreement in the data for evaporated films
. In addition to thickness, substrate temperature and deposition press
ure were varied to examine their effect on the microstructure. The fil
m microstructure was characterized by x-ray diffraction, transmission
electron microscopy, and Auger spectroscopy. The polycrystalline films
did not display a strong preferred orientation and had average grain
sizes of 60-85 angstrom. Surface oxide layers formed upon exposure to
air ranged from 10 to 80 angstrom, the thicker oxides formed on films
with lower density. Magnetic hysteresis measurements were made with a
vibrating sample magnetometer. Below 1000 angstrom, porosity and surfa
ce oxidation result in reductions up to 15% in the saturation magnetiz
ation. An anomalous peak in coercivity at film thicknesses of 300-500
angstrom was observed, which can be explained by the change in domain
wall type.