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[Fe.sub.53][Pt.sub.47] and [Fe.sub.58][Pt.sub.42] thin films with 300 nm in thickness prepared using magnetron sputtering were investigated. The films were deposited on heated glass substrates and annealed at 400[degrees]C and 800[degrees]C for different time. Single phase FePt films with similar chemical ordering but different substructure size were produced in the two series of samples. The effect of microstructure refinement results in significant enhancement in remanence ([M.sub.r]) of about 38.1% and 30.8% in the [Fe.sub.53][Pt.sub.47] and [Fe.sub.58][Pt.sub.42] films, respectively. The energy product, [(BH).sub.max], also showed a large increase of 25% and 72%; the maximum value of the two series of films are 16.2 MGOe and 19.6 MGOe, respectively. The large [(BH).sub.max] was found to originate from the enhancement of [M.sub.r] and steep slope of demagnetization curve at coercive point ([alpha]). As the theoretical predictions, in an isotropic magnet, the magnetic moments in the transition region of magnetization near grain boundary are easy to be aligned by applied field. In this study, it is found that by increasing the magnetic transition region through microstructure refining, the remanence can be effectively enhanced meanwhile facilitate the collective magnetic reversal. Domain structure confirms that the refinement of microstructure effectively reduces the domain size. Index Terms--Energy product, exchange coupling, FePt, microstructure refinement, reversible magnetization.

The Nd2Fe14B single-layer and [(NdFeB)(sub x)/ (Nb, Cr)](sub n) multilayer magnetic properties and microstructure are compared in order to discuss the film magnetization reversal using the modified nucleation and pinning models. The Nb Spacer layer enriched the grain boundaries of the Nd3Fe14B phase, which in turn inhibited the grain growth.

We deposited face-centered cubic (FCC) Co films on glass substrates by sputtering. From Auger-depth profile analysis, we found that there is one CoO layer, about 13 [Angstrom] thick, lying on the top surface of the Co film, and another CoO layer, about 37 [Angstrom] thick, lying within the Co/glass interface. At room temperature, the thin CoO film is supposed to be paramagnetic. However, because of the proximity effect between CoO and Co, the CoO layer may become ferromagnetic, with saturation magnetization Mo. By fitting the saturation magnetization ([M.sub.s]) data of the whole Co/CoO film as a function of (1/[t.sub.f]), where [t.sub.f] is the Co thickness, we can prove that the last conjecture is correct, and the [M.sub.o] of the CoO layer is indeed not zero. Both the [t.sub.f] dependence of the magnetostriction constant ([[lambda].sub.s]) and the [t.sub.f] dependence of the coercive field ([H.sub.c]) show a two-region characteristic. The dividing line for the former quantity is at [t.sub.f] = 88 [Angstrom], and for the latter it is at [t.sub.f] = 120 [Angstrom]. When crossing such a dividing line, there is a discontinuous jump in [[lambda].sub.s] (or [H.sub.c]). These phenomena occur because the lattice-strain and magnetoelastic effects within the CoO layer dominate the ([[lambda].sub.s]) and the [H.sub.c] behavior in ultra-thin ([t.sub.f] < 88 [Angstrom]) Co films. In this region, the roughness-to-thickness ratio ([S.sub.q]/[t.sub.f]) may also affect ([[lambda].sub.s]). Finally, there seems to be no connection between the grain size (D) and [H.sub.c]. Index Terms--Co film, magnetostriction, proximity effect.