[en] We report static magnetization measurements on the compositionally modulated ferromagnetic alloy Cu/Ni, which, contrary to earlier ferromagnetic resonance measurements, show the moment per Ni atom is reduced relative to pure Ni. The low-temperature magnetization is found to vary linearly with modulation amplitude, but, surprisingly, the Curie temperature is found to be almost amplitude independent

[en] The authors have studied the superconducting properties of V/Cr superlattices. Superlattices of V₁₀₀Cr_x, V₁₅₀Cr_x, and V₂₀₀Cr_x, with x varying between 3 and 80 atomic planes have been prepared. The films have a strong (110) texture and were grown on sapphire substrates at 250⁰C in an ultra-high vacuum system. The zero field transition temperature of the V₁₅₀Cr_x and V₂₀₀Cr_x, but not the V₁₀₀Cr_x, films have been adequately modeled using Werthamer's theory for proximity effect coupled films. The films have a dimensional crossover in the parallel upper critical field when the thickness of the Cr layers is about 60 atomic planes

[en] Synthetic crystals of layered titanium silver were grown epitaxially by vapor deposition techniques. The motivation was to generate a one-dimensional diffraction grating to be used as a soft x-ray monochromator. The structural analysis shows that the as-grown film is almost a single crystal, where a new phase is present, characteristic of the layering process. The results indicate that it is now becoming feasible to produce new synthetic crystals by vapor deposition of two chemically quite dissimilar metals

[en] We present measurements of the transition temperature and upper parallel critical field, to 15 kG, of layered Nb-Ti alloys for layer wavelengths between 6 and 6250 A

[en] The composition dependence of superconductivity and crystal structure in La(Ba_1-chiCa_chi)₂Cu₃O_7-y system was determined by the resistivity measurements and X-ray diffraction analysis. The superconducting transition temperature is raised with the increase of Ca content till chi=0.6, at which the zero resistance temperature of the sample is 81.5Κ. In the meanwhile, the crystal structure of the sample changed from tetragonal (chi=0) to orthorhombic structure (chi=0.2,0.4,0.6). With further increase of Ca content, the superconductivity decrease for the sample of chi=0.8 with mixed phases including the orthorhombic oxygen-deficient perovskite-like (ODP) structure and no superconducting transition is found at 4.2Κ for the sample of chi=1 without the ODP structure. A possible explanation of these experimental results is given

[en] Epitaxial thin films of YBaCuO were prepared by multilayer deposition from Y, Cu, and BaF₂ sources with: (1) the a-axis perpendicular to (100)SrTiO₃; (2) the c-axis perpendicular to (100)SrTiO₃; and (3) the [110] axis perpendicular to (110)SrTiO₃. XRD patterns as well as SEM and HREM images confirm that the films are highly oriented, essentially epitaxial. Both the a-axis oriented and the c-axis oriented films exhibit zero resistance at 91K. The [110] oriented film shows the sharpest transition with a transition width of 1K and zero resistance at 85K. The zero field critical current density, J_c, determined magnetically, is in excess of 10⁷A/cm² at 4.4K and 1.04 x 10⁶A/cm² at 77K for the c-axis oriented film; for the a-axis oriented film the authors obtained 6.7 x 10⁶A/cm² at 4.4K and 1.2 x 10⁵A/cm² at 77K. The orientation dependence of the critical current density in the basal plane of the a-axis oriented film was studied. The largest J_c's occur along the in-plane < 100 > axes of the substrate

[en] The propagation characteristics of dust acoustic shock waves have been investigated in an unmagnetized nonuniform dusty plasma containing dust grains with nonadiabatic changed charges and different size, electrons and ions modeled by kappa distribution. The modified Korteweg-de Vries Burgers equation is derived by using the standard reductive perturbation technique. Numerical and theoretical analyses show that there are two different shock structures, that is, oscillatory shock structures and monotonous shock structures, in system. The results show that the dust size with power law distribution and kappa parameters have an important influence on dust acoustic shock waves. (author)

[en] We report detailed measurements of the magnetization of Cu/Ni composition modulated foils as a function of temperature, magnetic field, composition wavelength, and composition amplitude. We find a Curie temperature that initially increases rapidly with wavelength but quickly saturates. We also find that the Curie temperature is independent of composition amplitude which we ascribe to the existence of disk-like Ni clusters

[en] The Bi-Sr-Ca-Cu-O superconductor with the nominal composition (1113) were prepared. An orthorhombic unit cell (a=0.544nm, b=0.543nm, c=3.07nm) was determined by X-ray diffraction. The resistance transition curve shows that the sample has an onset around 110Κ and the zero resistance temperature at 85Κ. The mutual inductance measurement also shows a two-step transition which correspond to two superconducting phases as well as that in the resistive transition. The specific heat measurement was performed in the range of 56Κ to 130Κ by continuous scanning method. A simple extrapolation of the curve was made both from below and above T_c to yield ΔC=45mj/g.Κ and ΔC/T_c=0.49mj/g.Κ². From these values, the Sommerfeld constant γ and the Debye temperature θ_D were estimated

[en] This paper reports what the authors believe to be the first real time, in situ studies of film growth by sputtering using synchrotron X-rays; the structure and growth habit of YBa₂Cu₃O₇ (YBCO) thin films deposited on (100) SrTiO₃ in a miniature, faced- magnetron sputtering system have been investigated. A combination of the substrate temperature and the deposition rate determines whether the film grows along the a, c, or multiple axes. At low substrate temperatures and low deposition rates, the films grow preferentially along the a- axis. In contrast, higher substrate temperatures and high deposition rates favor c-axis oriented film growth with some admixture of (220). The X-ray diffraction peaks were monitored in real time revealing that both a-axis and c-axis oriented grains nucleated on the surface of the (100) SrTiO₃ between 625 degrees and 765 degrees C, although the volume fraction of each orientation was temperature dependent