Fe n /V m superlattices with nϭ2,4 and mϭ2,4,5 are studied by vibrating sample magnetometry and x-ray magnetic circular dichroism measurements. The combination of both techniques allows us to determine absolutely the induced V magnetic moment per atom. The samples with the thinnest V or Fe layers, respectively, reveal the largest induced moment of m V ϭϪ1.1 B /atom (Fe 4 /V 2 ) and the strongest reduction of the Fe moment down to m Fe ϭ1.34 B /atom (Fe 2 /V 5 ). In addition, we probe the orbital magnetism of Fe and discuss it with respect to previous results by ferromagnetic resonance and first principles calculations.

The temperature dependence of the interlayer exchange coupling in ferromagnetic films coupled across nonmagnetic spacers is determined via in situ ferromagnetic resonance experiments for various systems. Clear evidence for a T(3/2) law is found over a wide temperature regime.

The influence of the strain state on the thermodynamics of hydrogen in quasi-two-dimensional potentials is reported. The host lattice is V embedded in Fe in the form of a Fe/V(001) superlattice, which represents a strongly confined absorption potential extending over just 13 monolayers. ΔH̄H and ΔS̄H for the continuous solubility region are calculated from the measured isotherms. Two phase transitions are observed for atomic ratios up to c = 1 in the temperature region 50-300 °C. The first transition occurs in the range 0.03⩽c⩽0.07, and shows a Curie-Weiss behaviour. No corresponding phase boundary exists in bulk vanadium hydrides. The second transition, at c≃0.35 and T<150 °C, exhibits large hysteresis and involves an ordering not previously observed in thin vanadium layers. The site blocking at low concentrations scales linearly with the initial strain and yields a blocking concentration of c = 0.083(1) at zero strain, as compared to 0.415(9) in bulk V. This difference is ascribed to the finite-size of the host lattice.

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Arrays of Co particles with well-defined geometry and lateral sizes in the range 0.1–0.5 μm were prepared by electron beam lithography and studied by magnetization measurements and magnetic force microscopy. The starting materials were epitaxial Co films, with in-plane magnetic anisotropy, having thicknesses in the range 10–50 nm. The particles change from multidomain behavior to that of stable single domains in zero field, as the lateral dimension decreases within these ranges. For particles of circular shape, i.e., without in-plane shape anisotropy, the critical size for forming single domains was found to be about 200 nm in lateral extension and 20 nm thickness. Elliptical particles prepared with 20 nm thickness and lateral dimensions 150 by 450 nm were found to be stable single domains, of good uniformity, in zero field. The switching of these particles from one magnetization direction along the long axis to the other, requires an applied field BS≈(100±20)mT. A comparison with other published results leads to the conclusion that although the critical volume for single domains may be about the same, the final microscopic magnetic structure and the processes for magnetic switching for particles in the actual range of sizes, are strongly governed by the intrinsic properties of the Co films, which may vary widely.