With varying thickness of the spacer near the second oscillatory GMR peak in Co/Cu system, a series of glass/Fe/[Co/Cu]20/Co multilayers are prepared by magnetronsputtering technique. The MR values are relatively small. High angle X-ray di raction shows that the copper crystallizes in fcc structure with (111) texture and the cobalt crystallizes in hcp structure with (002) preferential orientation. There is a mixed amorphous CoCu layer at the interface due to the di usion between cobalt and copper, which may decrease the MR value. The thickness, the mass density for each sub-layer and the surfacial and interfacial roughnesses are re ned from the X-ray specular reflectivity measurement.

y was observed in the interface width, that of the Si layer becoming very large. When this was observed, the measured Ge layer thickness was substantially less than the nominal thickness determined from the growth parameters. X-ray diffuse scattering easurements show that the topological roughness was small. The data are interpreted in terms of diffusion of Ge into the Si beneath the Ge layer, a modified Stranski–Krastanov growth mode resulting in the formation of a 3-dimensional "inverted hut" structure of Si-Ge islands. Grazing incidence X-ray scattering provides a rapid and non-destructive technique for the identification of the growth mode. 2003 Elsevier B. V. All rights reserved.

A dynamic model of anisotropic x-ray diffraction is developed using two-wave approximation. A dispersion surface equation is derived for the screw-axis and glide-plane forbidden reflections. Propagation and polarization phenomena of waves are discussed. The deductions show that all these forbidden reflections may be excited except the 00l (l52n11) reflections for a 63 screw axis and the 00l (l56n13) reflections for 61 and 65 screw axes. The general methods are illustrated by their application to the rutile structure. [S0163-1829(99)3330-5]

For GdFe/NiCoO bilayers after field cooling, hysteresis loops at low temperatures are shifted along both the horizontal and vertical axes. The exchange field HE changes from negative values to positive values with increasing cooling field HCF and the coercivity HC acquires a maximum near the crossover of HE.At 5K, HE and HC at HCF=3 T and the peak height DHC are proportional to the inverse GdFe layer thickness. At HCF=3 T, HE is always positive in the temperature region from 5 to 350K. At low HCF, however, HE is negative at low temperatures and becomes positive at high temperatures. These results can be ascribed to antiferromagnetic coupling between GdFe and NiCoO layers.

Nd doped Y0.8 Ca0.2 Ba2-x Ndx Cu3 Oy YBNCO compounds with x≤.50 have been prepared by the solid state reaction technique. The structure and the superconductivity for YBNCO compounds are characterized. The zero resistance transition temperature T for each sample was measured. T increases with the increase of the content of Nd in YBNCO as xF0. 15, c0 c0 and decreases as xG0.20. X-ray diffraction studies show that there is no structural phase transition in the whole doping range. The dependencies of the lattice constants and some other structural parameters on the content of Nd for the samples YBNCO with xF0.20 have different behaviour than that for the samples with xG0.25. It seems that the uperconductivity of YBNCO is related to the structural changes due to Ca and Nd co-doping. q1999 Published by Elsevier Science B. V. All rights reserved.