We report a systematic study of <100> epitaxial films of magnetite (Fe3O4) of thickness 300-2000 Å, grown on single-crystal substrates (MgO, MgAl2O4, and SrTiO3) using pulsed laser deposition. The magnetic state was explored by measuring magnetization, conversion-electron Mössbauer spectroscopy, and ferromagnetic resonance. At 300 K, films grown on MgAl2O4 and SrTiO3 are, more or less, normal for all thicknesses. That is, the in-plane anisotropy is fourfold. The films on MgO, however, show no in-plane anisotropy if the thickness is less than ∼800 Å. In contrast to some previous claims, the present films exhibit magnetic saturation at quite modest (≤2 kOe) fields. We propose simple models to account for a variety of observations. In addition to the shape anisotropy, strains appear to play the major role in determining the variation of the magnetic behavior with thickness, substrate, and temperature.
|Original language||English (US)|
|Number of pages||9|
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|State||Published - Nov 15 2001|
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics