Abstract: When a condensate is sheared by imparting a velocity to a part of the condensate, phase singularities must appear at the interface between the region that is still at rest and the region that has acquired a velocity. For helium, Feynman argued that these phase singularies will arrange themselves in the form of a vortex row. BoseEinstein condensates of ultracold atomic gases differ from helium in that the healing length is generally much larger and is, in fact, tunable. Another difference is that multicomponent condensates can be created, where the two components forming the mixture are usually two different hyperfine states of the condensed atoms. These two components can be manipulated separately and can be interconverted. In this contribution, we investigate how these additional degrees of freedom, available in quantum gases, change what happens in sheared condensates. In particular, we consider skyrmion rows as an alternative to vortex rows, and we also consider phase slip lines filled with the second, unmoving component, in a condensate mixture. We show that depending on the ratios of the interaction strengths between the components, and depending on the shear velocity, skyrmion rows and phase slip lines can become lower in energy than vortex rows, and hence should be observable in quantum gases. Moreover, we find that the velocity field affects the stability region of the condensate with respect to phase separation.

Abstract: We report on the preparation of CuBa(2)(Sr(x)Ca(1-x))(n)Cu(n-1)O(y) compounds by fabrication of (Ba,Sr,Ca)CuO(2) superlattices with pulsed laser deposition (PLD). A technique called interval deposition is used to suppress multi-level or island growth resulting in high-quality superlattice structures. Both, the applicability of PLD to atomic engineering as well as the fabrication of artificial superconductors is demonstrated. The (Sr,Ca)CuO(2)-BaCuO(2) superlattices are characterized by X-ray diffraction, high-resolution electron microscopy (HREM) and selected area electron diffraction. The superlattice period has been deduced from electron diffraction patterns and XRD measurements. For Sr containing films, the best growth behavior is observed and films with the highest degree of crystallinity are obtained, whereas superconductivity is only found in less crystalline, Ca containing films. Under some deposition conditions and depending on the amount of Ba containing layers in the superlattice, it was observed that the BaCuO(2) material is converted to Ba(2)CuO(4-delta). Image simulations to interpret the HREM contrast are performed. (C) 2001 Elsevier Science B.V. All rights reserved.

Abstract: Using pulsed laser deposition ultra-thin DyBa2Cu3O7-x films were deposited on a single terminated (0 0 1) SrTiOr(3) substrate. The initial growth was studied by high-resolution electron microscopy. Two different types of interface arrangements occur and were determined as: bulk-SrO-TiO2-BaO-CuO-BaO-CuO2-Dy-CuO2-BaO bulk and bulk-SrO-TiO2-BaO-CuO2-Dy-CuO2-BaO-CuO-BaO-bulk This variable growth sequence causes structural shifts, resulting in antiphase boundaries with displacement vector R = [0 0 1/3]. as well as local chemical variations. (C) 2001 Elsevier Science B.V. All rights reserved.

Abstract: YBCO-based materials containing SO4-tetrahedra centered on the Cu(1)-sites of the CuO-chain plane have been examined by means of electron diffraction and high resolution electron microscopy. An incommensurate modulation is observed and attributed to the ordering of b-oriented SO4-rich chains in the Cu(1)-S-O-layer, described in terms of an SO4-concentration wave.

Abstract: We study the vortex profiles in two-gap superconductors using the extended Ginzburg-Landau theory. The results shed more light on the disparity between the effective length scales in two bands. We compare the behavior expected from the standard Ginzburg-Landau theory with this new approach, and find good qualitative agreement in the case of LiFeAs. (C) 2011 Elsevier B.V. All rights reserved.

Abstract: The microstructure of (Bi,Pb)2Sr2Ca2Cu3Ox (Bi-2223) tapes has been investigated by means of transmission electron microscopy (TEM) and high-resolution TEM. The emphasis has been placed on: (1) an examination of the grain morphology and size, (2) grain and colony boundary angles, which are formed during the tape processing, (3) a study of the grain boundaries on an atomic scale, including intergrowth investigations. Tapes with different process parameters have been compared with respect to the microstructure. A fully processed tape has on the average 50% thicker Bi-2223 grains than a tape after the first annealing. The angles of c-axis tilt grain boundaries are on average 14° and 26° for the fully processed tape and the tape after the first annealing, respectively. The intergrowth content (15%) and distribution are similar in these two tapes.

Abstract: In Bi2Sr2Ca0.6Y0.4Cu2Oy single crystals we have identified the intergrowth of two phases; a normal Bi2Sr2CaCu2Oy type phase with a 4.6b modulation period and a secondary,phase with a 9.4b modulation period. Both the two phases have orthorhombic basic structures with similar lattice parameters but different symmetries, i.e. Bbmb for the normal phase and Ccca for the secondary phase. The c-parameters of these two phases are found to vary independently upon changing the nominal Y content. The modulation characteristics of the secondary phase implies a close structural relation between the two phases. Both phases are discussed from a structural and a compositional point of view.

Abstract: The pattern formation of the vortex states with non-monotonic inter-vortex interaction is investigated. Our applied model has a short-range repulsive (r < r(c)) and long-range attractive (r > r(c)) potential. We numerically calculate the stable states using molecular-dynamics simulations. The obtained vortex patterns are comparable with the vortices states in low kappa type-II superconductors and recently discovered "type-1.5'' superconductors. We also analyze the nearest neighbor distribution of the obtained patterns. (C) 2012 Published by Elsevier B.V.

Abstract: A superconducting rod with a magnetic moment on top develops vortices obtained here through 3D calculations of the GinzburgLandau theory. The inhomogeneity of the applied field brings new properties to the vortex patterns that vary according to the rod thickness. We find that for thin rods (disks) the vortex patterns are similar to those obtained in presence of a homogeneous magnetic field instead because they consist of giant vortex states. For thick rods novel patterns are obtained as vortices are curve lines in space that exit through the lateral surface.