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We report on the magnetic and structural characterization of high lattice-mismatched [Dy 2nm /Sc t Sc ] superlattices, with variable Sc thickness t Sc = 2-6 nm. We find that the characteristic in-plane effective hexagonal magnetic anisotropy K 6,ef 6 reverses sign and undergoes a dramatic reduction, attaining values of ≈13-24 kJm −3 , when compared to K 6 6 = −0.76 MJm −3 in bulk Dy. As a result, the basal plane magnetic anisotropy is dominated by a uniaxial magnetic anisotropy (UMA) unfound in bulk Dy, which amounts to ≈175-142 kJm −3 . We attribute the large downsizing in K 6,ef 6 to the compression epitaxial strain, which generates a competing sixfold magnetoelastic (MEL) contribution to the magnetocrystalline (strain-free) magnetic anisotropy. Our study proves that the in-plane UMA is caused by the coupling between a giant symmetry-breaking MEL constant M 2 γ,2 ≈ 1 GPa and a morphic orthorhombiclike strain ε γ,1 ≈ 10 −4 , whose origin resides on the arising of an in-plane anisotropic strain relaxation process of the pseudoepitaxial registry between the nonmagnetic bottom layers in the superstructure. This investigation shows a broader perspective on the crucial role played by epitaxial strains at engineering the magnetic anisotropy in multilayers.

In this paper we present re-analyses of magnetostriction measurements earlier performed in terbium, dysprosium and holmium single crystals. In the framework of the standard theory of single-ion crystal-electric-field and two-ion exchange magnetostrictions, we explain the thermal variation of the anisotropic saturation magnetostriction within the basal plane by considering high-order terms in the magnetoelastic energy. Using complementary basal-plane magnetic anisotropy measurements, we have been able to obtain the second- and fourth-order magnetoelastic coupling parameters associated with the orthorhombic distortion of the hexagonal plane for the above-mentioned three heavy rare earths.

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We present a structural, morphological, magnetic, and magneto-optical study of cobalt nanoparticles deposited on 50 Å AlN/c-sapphire substrates and embedded in an AlN matrix. The dependence of the properties of Co nanoclusters deposited on AlN with growth temperature and amount of deposited Co are studied and discussed. Also we directly compare the properties of as grown and AlN embedded Co nanoclusters and show that the AlN matrix has a strong impact on their magnetic and magneto-optical properties.

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We present a fully automated vector vibrating-sample magnetometer where the sample can be rotated against the applied magnetic field Hap, so that the angular dependence of the longitudinal, Mlong, and transversal, Mtrans, components of M with respect to Hap on the rotation plane are determined. The magnetic field range is ±20kOe and temperature ranges between 4.2 and 340 K. The resolution is better than 2×10−7emu and the sensitivity is 5×10−6emu. Standard hysteresis loop measurements are possible as well. As examples of its capability we display torque curves performed at low temperatures in a [Ho8Lu15]50 superlattice and in a 60-nm-thick Terfenol-D thin film.

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