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Multilayers of [Co/Pt]20, with tCo/tPt≐7 and the period Λ in the range of 0.27–0.69 nm, and [Co(0.46 nm)/Pt(0.07–0.14 nm)]20 have been prepared by sputtering at low deposition rates and a high Ar pressure of 7.8 Pa. Structure and magnetic properties were characterized by x-ray diffraction, transmission electron microscopy, magnetometry measurements, and magnetic force microscopy. Column structure, coherent stacking of Co and Pt layers, and small grains have been observed. The average atomic interplane distance d111 changes with the constituent layer thickness. In the first series of Co/Pt multilayers, the out-of-plane coercivity gradually increases to reach a maximum, with the bilayer period increasing from 0 to 0.58 nm, and decreases with further increasing period. For the second series, the out-of-plane coercivity increases to reach a maximum of 6.5 kOe with tPt increasing from 0.07 to 0.13 nm and decreases with further increasing tPt. In order to explain the strong magnetic perpendicular anisotropy, the magnetoelastic energy of CoPt alloy layers must be taken into account. [ABSTRACT FROM AUTHOR]

In-grain microplasticity and intergranular microdamage in polycrystalline hexagonal-structure ceramics subjected to a sequence of dynamic compression and tension are studied computationally using the Voronoi polycrystal model, by which the topological heterogeneity and material anisotropy of the crystals are simulated explicitly. The constitutive modeling considers crystal plasticity by basal slip, intergranular shear damage during compression, and intergranular mode-I cracking during tension. The model parameters are calibrated with the available shock compression and spall strength data on polycrystalline α-6H silicon carbide. The numerical results show that microplasticity is a more plausible micromechanism for the inelastic response of the material under shock compression. On the other hand, the spallation behavior of the shocked material can be well predicted by intergranular mode-I microcracking during load reversal from dynamic compression to tension. The failure process and the resulting spall strength are, however, affected strongly by the intensity of local release heterogeneity induced by heterogeneous microplasticity, and by the grain-boundary shear damage during compression. [ABSTRACT FROM AUTHOR]

Structure and transport properties of Eu-doped YBa2-xEuxCu3O7-δ (YBECO) have been studied. Eu is confirmed preferring to replace Ba at Ba sites. The averaged valence state of Eu, which is examined by x-ray photoemission spectroscopy, increases with increasing x. Eu doping in YBECO has a little influence on superconductivity in our studies, and the superconducting transition temperature Tc is almost unchanged. [ABSTRACT FROM AUTHOR]

We have observed that the extraordinary Hall resistance of Pt/Co/Pt sandwich with perpendicular magnetic anisotropy changes from positive to negative drastically as the current density increases in an applied field, indicating the magnetization switching induced by the current. There exists a critical current density that changes for the different applied field with the order of current density of 104 A/cm2, which is much lower than that reported in literatures on the current-induced magnetization switching. The results of the extraordinary Hall effect of the sample in different in-plane current density show that the magnetization-switching field decreases with the increment of current density when the current density is larger than 104 A/cm2. [ABSTRACT FROM AUTHOR]

(001)-oriented FePt films are deposited, by magnetron sputtering at 300 °C, on LaAlO3 (001), SrTiO3 (001), and MgO (001) single crystal substrates. The tetragonal distortion, magnetic anisotropy, and the coercive force of the films vary with the substrate. The ordering process is very different with the substrate, which may affect the magnetic properties of the film. The magnetic coercivity decreases with increasing the ordering parameter and the tetragonal distortion, which may be ascribed to the lattice strain. [ABSTRACT FROM AUTHOR]