EXCHANGE-ANISOTROPY IN NIFE FE-DOPED NIO BILAYERS/

Fe-doped NiO polycrystalline and {111} epitaxial films were grown by s olid-source metalorganic chemical vapor deposition. The exchange field for NiFe on the polycrystalline Fe-doped NiO films increased with Fe content up to 18 at. % Fe, and then decreased with further increases i n Fe content; the coercivity, blocking temperature, and grain size mon otonically decreased with increasing Fe content. Similar results were observed in {111} films. The increase of the exchange field and the re duction of the blocking temperature are attributed to dissolved Fe ato ms in the NiO. Low exchange coupling between NiFe and alpha-Fe2O3 may be responsible for the decrease of the exchange field in highly Fe-dop ed NiO films. Furthermore, 18% Fe-doped NiO showed an enhancement of e xchange fields at thicknesses between 450 and 950 Angstrom, and a cons iderable large training effect was observed. (C) 1997 American Institu te of Physics.