Oxides and surface magnetism. Final report

The general objective of this program was to study the magnetism and structure of iron oxide films with a view to enhancing control over growth mode, oxidation state and fundamental understanding in this complex system. In particular, the authors sought to create new magnetic metal/oxide multilayers and composites based on improved knowledge of the magnetic properties at Fe and Fe{sub 3}O{sub 4} surfaces and at Fe/Fe{sub 3}O{sub 4} interfaces. The project had three parts: (1) deposition and characterization of iron films up to 0.1 {micro}m on fused quartz, (2) deposition and characterication of Fe{sub 3}O{sub 4} films up to 0.1 {micro}m on fused quartz and (3) fabrication and characterization of Fe/Fe{sub 3}O{sub 4}/{hor_ellipsis}multilayers. (1) The structure and magnetic properties of sputtered Fe/SiO{sub 2} were studied first. The most interesting result here is the variation of magnetic properties with Fe film thickness, t. M{sub s} is approximately 1680 gauss and H{sub c} {approx} 25 Oe for t > 0.1 micron. (2) The Fe oxide study (task 2) proved to be very important. By using reactive sputtering, the authors were able to locate a robust processing region, which would give thickness independent properties for the Fe{sub 3}O{sub 4} to be used in the multilayer studies. In addition they synthesized ferromagnetic Fe{sub 1{minus}x}O, the first report of such a phase. The ferromagnetism is attributed to the cation disorder. (3) The purpose of the multilayer study (task 3) was to see if Fe could be used to enhance the moment and possibly the coercivity of magnetic oxides