Si/Ta/Co/Cu/CoFeMn sor NiOd spin valves were prepared by a delayed sputtering procedure, in which depositions of Ta and followed layers were intervened by 1 h. The spin valves are found to have better coherent growth with stronger s111d preferred orientations in Co and Cu layers, compared with the traditional continuous method. At the same time, the giant magnetoresistance ratio and spin-dependent scattering are enhanced by a factor of 20%-30%. These results indicate that the coherent growth and the s111d preferred orientation can enhance the spin-dependent scattering of spin valves.

Cations of Y and Sr co-substituting for La and Ca at A site in La2/3Ca1/3MnO3 compound, a2/3−xYxCa1/3−ySryMnO3, were synthesized successfully by solid-state reaction. X-ray diffraction shows there is only one phase with the dopants of Y and Sr within x≤0.20 or y≤0.19. The lattice parameters along a-, b-, and c-direction remain almost unchanged with x≤0.20. The bond angle of Mn O Mn ncreases from 151.9 for x=0 to 172.7 for x = 0.20 monotonically, which indicates that the Jahn-Teller effect in MnO6 octahedron decreases with increasing x. The temperature dependence of resistance with/without magnetic applied were measured and fitted theoretically. The metal-to-insulator transition emperature, TMI, decreases with increasing the Y content with x≤0.10 while TMI increases slightly with further increasing x. The Y-content dependence of magnetoresistance shows a parabolic behavior. The maximum MR value corresponds to x=0.08-0.10.We attributed these variations in the structure and transportation to the cation disorder due to the cation doping.

The mercury-based superconductor Hg-1223 with Pb substituted for Hg has a transition temperature (T RD0 c, the zero-resistance temperature, 135K; T diac, the diamagnetic onset temperature, D 143K) higher than that for pure Hg-1223 compound. The structure of this Pb-doped sample has been nvestigated via neutron powder diffraction. Some selected bond distances are compared to those of Pb-free Hg-1223 cuprate. The contents of Pb and oxygen have been refined. The estimated valence of copper is about 2. 30, which is consistent with that for YBCO superconductor.

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.

The film of La2/3Ca1/3MnO3 (LCMO), YBa2Cu3O7−δ (YBCO) and YBCO/LCMO bi-layer were prepared by rf off-axis magnetic sputtering technique on SrTiO3 (STO) substrate. The structures, including the surface and interfacial morphology, the interfacial diffusion and so on, have been characterized by X-ray diffraction (XRD), auger electronic energy spectroscopy (AES) and atomic force microscopy (AFM). Through a 50-200eV energy range, a single layer of YBCO shows a very small reflectance (<2%), while a single layer of LCMO shows a higher reflectance of about 25% at the energy of about 75eV, which is much higher than that of metal W. Even higher reflectance (>50%) at about 75eV has been observed in the LCMO/YBCO bi-layers.