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Sample records for superconducting multilayers samples

  1. Quasiperiodic metallic multilayers: Growth and superconductivity

    SciTech Connect

    Karkut, M.G.; Triscone, J.; Ariosa, D.; Fischer, O.

    1986-09-15

    We have magnetron-sputtered a series of Mo-V superlattices which have a quasiperiodic layering in the growth direction. We have used the Fibonacci series as the generating rule for the nearly periodic structures and have verified their structure using high-angle x-ray diffractometry. The superconducting transition temperatures slowly increase as a function of the quasiperiodic wavelength ..lambda../sub F-italic/ while the initial upper-critical-field slopes parallel to the films decrease with increasing wavelength and the parallel upper-critical-field curves H-italic/sub c-italic//sub 2//sub chemically bond//sub chemically bond/ display a two-dimensional behavior that is not consistent with current ideas about critical-field behavior in multilayers.

  2. Superconductivity and magnetic properties of Fe/Nb multilayers (abstract)

    SciTech Connect

    Muehge, T.; Zoller, I.; Westerholt, K.; Zabel, H.; Tagirov, L.R.

    1996-04-01

    Interplay between superconductivity (SC) and ferromagnetism (FM) in dilute magnetic alloys and intermetallic compounds attracted considerable attention during the last 30 years. Usually the FM state is more stable and therefore tends to suppress SC. On the other hand, the magnetic state can be changed due to a modification of the RKKY interaction in the SC state. Mutual influence of SC and FM may acquire new peculiarities in such artificial systems as FM/SC multilayers. This work is focused on the study of Fe/Nb multilayered system, prepared on Al{sub 2}O{sub 3}(11{bar 2}0) substrates by rf-sputtering and by molecular beam epitaxy (MBE) techniques. The Nb thickness {ital t}{sub Nb} was varied from 150 to 500 A and the Fe thickness {ital t}{sub Fe} was changed from 5 to 100 A. The sputtered samples were highly layered with sharp interfaces as revealed by x-ray reflectivity and were textured in the [110] direction. The epitaxial MBE samples showed (110) growth of Nb and Fe with a coherence lengths comprising the total film thickness. Surface and interface roughnesses were very small. The dependence of the ferromagnetic resonance (FMR) spectra parameters on the direction of the dc magnetic field rotating in the plane of the samples show sixfold anisotropic behavior indicating the well known three-domain in-plane structure of Fe layers on sapphire substrates. FMR and SQUID measurements showed that FM of Fe layers survived down to {ital t}{sub Fe}=10 A. The out-of-plane FMR measurements also showed that the easy axis of magnetization lies in the plane of the samples down to this thickness. The superconducting transition temperature {ital T}{sub {ital c}} was determined by measurements of the electrical resistivity and by SQUID measurements. It was established that there is a critical thickness of the Fe layer {ital t}{sub Fe}{sup crit} above which SC was not detected for temperatures down to 1.5 K. This value was dependent on {ital t}{sub Nb}. (Abstract Truncated)

  3. Atomic layer deposition of thin superconducting films and multilayers

    NASA Astrophysics Data System (ADS)

    Proslier, Thomas; Klug, Jeffrey; Groll, Nikolas; Altin, Serdar; Becker, Nicholas

    2012-02-01

    We report the use of atomic layer deposition (ALD) to synthesize thin superconducting films and multilayer superconductor-insulator (S-I) heterostructures including: nitrides, carbides, and silicides, nitrides of molybdenum and titanium, and Nb1-xTixN/AlN-based S-I heterostructures. The atomic-scale thickness control afforded by ALD enables the study of superconductivity and associated phenomena in homogeneous layers in the ultra-thin film limit. Two-dimensional superconductivity in such films is of interest from a fundamental point of view, as a new effect has recently been discovered at ultra-low temperature in thin superconducting films made by ALD: the super-insulating transition. Furthermore, the ALD technique applied to superconducting films opens the way for a variety of applications, including improving the performance and decreasing the cost of high energy particle accelerators, superconducting wires for energy storage, and bolometers for radiation detection. In this respect, we will present results on the ALD growth processes, the metallurgy and superconducting properties of these coatings.

  4. Topological Crystalline Superconductivity in Locally Noncentrosymmetric Multilayer Superconductors.

    PubMed

    Yoshida, Tomohiro; Sigrist, Manfred; Yanase, Youichi

    2015-07-10

    Topological crystalline superconductivity in locally noncentrosymmetric multilayer superconductors (SCs) is proposed. We study the odd-parity pair-density wave (PDW) state induced by the spin-singlet pairing interaction through the spin-orbit coupling. It is shown that the PDW state is a topological crystalline SC protected by a mirror symmetry, although it is topologically trivial according to the classification based on the standard topological periodic table. The topological property of the mirror subsectors is intuitively explained by adiabatically changing the Bogoliubov-de Gennes Hamiltonian. A subsector of the bilayer PDW state reduces to the two-dimensional noncentrosymmetric SC, while a subsector of the trilayer PDW state is topologically equivalent to the spinless p-wave SC. Chiral Majorana edge modes in trilayers can be realized without Cooper pairs in the spin-triplet channel and chemical potential tuning.

  5. Topological Crystalline Superconductivity in Locally Noncentrosymmetric Multilayer Superconductors

    NASA Astrophysics Data System (ADS)

    Yoshida, Tomohiro; Sigrist, Manfred; Yanase, Youichi

    2015-07-01

    Topological crystalline superconductivity in locally noncentrosymmetric multilayer superconductors (SCs) is proposed. We study the odd-parity pair-density wave (PDW) state induced by the spin-singlet pairing interaction through the spin-orbit coupling. It is shown that the PDW state is a topological crystalline SC protected by a mirror symmetry, although it is topologically trivial according to the classification based on the standard topological periodic table. The topological property of the mirror subsectors is intuitively explained by adiabatically changing the Bogoliubov-de Gennes Hamiltonian. A subsector of the bilayer PDW state reduces to the two-dimensional noncentrosymmetric SC, while a subsector of the trilayer PDW state is topologically equivalent to the spinless p -wave SC. Chiral Majorana edge modes in trilayers can be realized without Cooper pairs in the spin-triplet channel and chemical potential tuning.

  6. Dynamic Matching of Vortex Lattice in Superconducting Multilayers

    SciTech Connect

    Gurevich, A.; Kadyrov, E.; Larbalestier, D.C.

    1996-11-01

    We observed oscillations of a nonlinear flux flow resistivity {ital R}({ital j},{ital H}) as a function of a parallel magnetic field 6{lt}{ital H}{lt}9 T in Nb-Ti/Cu multilayers. We show that the oscillations in {ital R}({ital H}), which have the field period {Delta}{ital H}{approx_equal}0.1 T independent of temperature and current, indicate a long-range order in the rapidly moving vortex structure. The critical current {ital I}{sub {ital c}}({ital H}) exhibits no oscillations characteristic of {ital R}({ital H}). We propose an explanation of the effect in terms of dynamic matching of the moving vortex lattice with periodic microstructure and show that both {Delta}{ital H} and the amplitude of the oscillations of {ital R}({ital H}) are inversely proportional to the sample thickness. {copyright} {ital 1996 The American Physical Society.}

  7. Superconducting nanowire single-photon detectors with non-periodic dielectric multilayers

    NASA Astrophysics Data System (ADS)

    Yamashita, Taro; Waki, Kentaro; Miki, Shigehito; Kirkwood, Robert A.; Hadfield, Robert H.; Terai, Hirotaka

    2016-10-01

    We present superconducting nanowire single-photon detectors (SSPDs) on non-periodic dielectric multilayers, which enable us to design a variety of wavelength dependences of optical absorptance by optimizing the dielectric multilayer. By adopting a robust simulation to optimize the dielectric multilayer, we designed three types of SSPDs with target wavelengths of 500 nm, 800 nm, and telecom range respectively. We fabricated SSPDs based on the optimized designs for 500 and 800 nm, and evaluated the system detection efficiency at various wavelengths. The results obtained confirm that the designed SSPDs with non-periodic dielectric multilayers worked well. This versatile device structure can be effective for multidisciplinary applications in fields such as the life sciences and remote sensing that require high efficiency over a precise spectral range and strong signal rejection at other wavelengths.

  8. Superconducting nanowire single-photon detectors with non-periodic dielectric multilayers

    PubMed Central

    Yamashita, Taro; Waki, Kentaro; Miki, Shigehito; Kirkwood, Robert A.; Hadfield, Robert H.; Terai, Hirotaka

    2016-01-01

    We present superconducting nanowire single-photon detectors (SSPDs) on non-periodic dielectric multilayers, which enable us to design a variety of wavelength dependences of optical absorptance by optimizing the dielectric multilayer. By adopting a robust simulation to optimize the dielectric multilayer, we designed three types of SSPDs with target wavelengths of 500 nm, 800 nm, and telecom range respectively. We fabricated SSPDs based on the optimized designs for 500 and 800 nm, and evaluated the system detection efficiency at various wavelengths. The results obtained confirm that the designed SSPDs with non-periodic dielectric multilayers worked well. This versatile device structure can be effective for multidisciplinary applications in fields such as the life sciences and remote sensing that require high efficiency over a precise spectral range and strong signal rejection at other wavelengths. PMID:27775712

  9. High temperature superconducting films and multilayers for electronics

    NASA Astrophysics Data System (ADS)

    Gavaler, John R.; Talvacchio, John

    1994-04-01

    The overall objective of this program was to develop a materials and fundamental device base for high-transition-temperature superconducting (HTS) electronics capable of operating at greater than 50K. Progress is reported on four tasks which address problems fundamental to the understanding of the superconducting state in HTS films, the application of HTS films in passive microwave circuits, the realization of HTS digital electronics, and the development of new superconducting devices. Large-area epitaxial YBCO films with low RF losses developed under this program and techniques for depositing them on both sides of single-crystal substrates were used in other Westinghouse and government-funded programs to develop HTS channelized filterbanks, delay lines, UHF antenna matching networks, and low-phase-noise resonators. An understanding was achieved of the role of oxygenation during film growth and the effect of film microstructure on RF losses. For HTS digital circuit fabrication, both active devices step-edge and edge-type YBCO Josephson junctions and trilayer BKBO junctions and passive structures were developed, such as crossovers, vias, and contacts. These capabilities were transfered to other Westinghouse and government-funded programs which demonstrated the first HTS SFQ circuits and SQUID's with integrated ground planes.

  10. Microelectronic superconducting device with multi-layer contact

    DOEpatents

    Wellstood, Frederick C.; Kingston, John J.; Clarke, John

    1993-01-01

    A microelectronic component comprising a crossover is provided comprising a substrate, a first high T.sub.c superconductor thin film, a second insulating thin film comprising SrTiO.sub.3 ; and a third high T.sub.c superconducting film which has strips which crossover one or more areas of the first superconductor film. An insitu method for depositing all three films on a substrate is provided which does not require annealing steps. The photolithographic process is used to separately pattern the high T.sub.c superconductor thin films.

  11. Microelectronic superconducting device with multi-layer contact

    DOEpatents

    Wellstood, F.C.; Kingston, J.J.; Clarke, J.

    1993-10-26

    A microelectronic component comprising a crossover is provided comprising a substrate, a first high T[sub c] superconductor thin film, a second insulating thin film comprising SrTiO[sub 3] ; and a third high T[sub c] superconducting film which has strips which crossover one or more areas of the first superconductor film. An in situ method for depositing all three films on a substrate is provided which does not require annealing steps. The photolithographic process is used to separately pattern the high T[sub c] superconductor thin films. 14 figures.

  12. Multi-layered chalcogenides with potential for magnetism and superconductivity

    SciTech Connect

    Li, Li; Parker, David S.; dela Cruz, Clarina R.; Sefat, Athena Safa

    2016-10-24

    Layered thallium copper chalcogenides can form single, double, or triple layers of Cu–Ch separated by Tl sheets. Here we report on the preparation and properties of Tl-based materials of TlCu2Se2, TlCu4S3, TlCu4Se3 and TlCu6S4. Having no long-range magnetism for these materials is quite surprising considering the possibilities of inter- and intra-layer exchange interactions through Cu 3d, and we measure by magnetic susceptibility and confirm by neutron diffraction. First principles density-functional theory calculations for both the single-layer TlCu2Se2 (isostructural to the ‘122’ iron-based superconductors) and the double-layer TlCu4Se3 suggest a lack of Fermi-level spectral weight that is needed to drive a magnetic or superconducting instability. Furthermore, for multiple structural layers with Fe, there is much greater likelihood for magnetism and superconductivity.

  13. Multi-layered Chalcogenides with potential for magnetism and superconductivity

    NASA Astrophysics Data System (ADS)

    Li, Li; Parker, David S.; dela Cruz, Clarina R.; Sefat, Athena S.

    2016-12-01

    Layered thallium copper chalcogenides can form single, double, or triple layers of Cu-Ch separated by Tl sheets. Here we report on the preparation and properties of Tl-based materials of TlCu2Se2, TlCu4S3, TlCu4Se3 and TlCu6S4. Having no long-range magnetism for these materials is quite surprising considering the possibilities of inter- and intra-layer exchange interactions through Cu 3d, and we measure by magnetic susceptibility and confirm by neutron diffraction. First principles density-functional theory calculations for both the single-layer TlCu2Se2 (isostructural to the '122' iron-based superconductors) and the double-layer TlCu4Se3 suggest a lack of Fermi-level spectral weight that is needed to drive a magnetic or superconducting instability. However, for multiple structural layers with Fe, there is much greater likelihood for magnetism and superconductivity.

  14. Superconducting composite with multilayer patterns and multiple buffer layers

    DOEpatents

    Wu, Xin D.; Muenchausen, Ross E.

    1993-01-01

    An article of manufacture including a substrate, a patterned interlayer of a material selected from the group consisting of magnesium oxide, barium-titanium oxide or barium-zirconium oxide, the patterned interlayer material overcoated with a secondary interlayer material of yttria-stabilized zirconia or magnesium-aluminum oxide, upon the surface of the substrate whereby an intermediate article with an exposed surface of both the overcoated patterned interlayer and the substrate is formed, a coating of a buffer layer selected from the group consisting of cerium oxide, yttrium oxide, curium oxide, dysprosium oxide, erbium oxide, europium oxide, iron oxide, gadolinium oxide, holmium oxide, indium oxide, lanthanum oxide, manganese oxide, lutetium oxide, neodymium oxide, praseodymium oxide, plutonium oxide, samarium oxide, terbium oxide, thallium oxide, thulium oxide, yttrium oxide and ytterbium oxide over the entire exposed surface of the intermediate article, and, a ceramic superco n FIELD OF THE INVENTION The present invention relates to the field of superconducting articles having two distinct regions of superconductive material with differing in-plane orientations whereby the conductivity across the boundary between the two regions can be tailored. This invention is the result of a contract with the Department of Energy (Contract No. W-7405-ENG-36).

  15. Multi-layered chalcogenides with potential for magnetism and superconductivity

    DOE PAGES

    Li, Li; Parker, David S.; dela Cruz, Clarina R.; ...

    2016-10-24

    Layered thallium copper chalcogenides can form single, double, or triple layers of Cu–Ch separated by Tl sheets. Here we report on the preparation and properties of Tl-based materials of TlCu2Se2, TlCu4S3, TlCu4Se3 and TlCu6S4. Having no long-range magnetism for these materials is quite surprising considering the possibilities of inter- and intra-layer exchange interactions through Cu 3d, and we measure by magnetic susceptibility and confirm by neutron diffraction. First principles density-functional theory calculations for both the single-layer TlCu2Se2 (isostructural to the ‘122’ iron-based superconductors) and the double-layer TlCu4Se3 suggest a lack of Fermi-level spectral weight that is needed to drive amore » magnetic or superconducting instability. Furthermore, for multiple structural layers with Fe, there is much greater likelihood for magnetism and superconductivity.« less

  16. Quasiperiodic superconducting V/Zr multilayers: critical magnetic fields and crossover

    NASA Astrophysics Data System (ADS)

    Fogel, N. Ya.; Cherkasova, V. G.; Mikhailov, M. Yu.; Bomze, Yu. V.; Yuzephovich, O. I.; Dmitrenko, I. M.; Stetsenko, A. N.

    1998-08-01

    Critical magnetic fields parallel and perpendicular to the planes of quasiperiodic superconducting Fibonacci multilayers (ML) consisting of vanadium and zirconium are measured. The temperature dependence of the parallel critical field Hc∥ displays two crossovers. The Hc∥(T) dependence is of square-root type in the vicinity of the transition temperature Tc and linear at low temperatures. Between these temperature intervals, the dependence follows a power law: Hc∥˜(1-T/Tc)α, α=0,78±0,02. The complex nature of this dependence can be explained in the framework of the Ginzburg-Landau theory for a quasiperiodic ML, as well as by the scaling theory for fractal multilayers which takes into account the different structure length scales in the case of ML with a complex sequence of layers.

  17. Multilayer coating for higher accelerating fields in superconducting radio-frequency cavities: a review of theoretical aspects

    NASA Astrophysics Data System (ADS)

    Kubo, Takayuki

    2017-02-01

    The theory of the superconductor-insulator-superconductor (SIS) multilayer structure for application in superconducting accelerating cavities is reviewed. The theoretical field limit, optimum layer thicknesses and material combination, and surface resistance are discussed for the SIS structure and are also reviewed for the superconductor-superconductor bilayer structure.

  18. Gamma-ray spectrometers using a bulk Sn absorber coupled to a Mo/Cu multilayer superconducting transition edge sensor

    SciTech Connect

    Chow, D T; Lindeman, M A; Cunningham, M F; Frank, M; Barbee, T W Jr; Labov, S E

    1999-09-21

    We are developing gamma-ray detectors with a bulk absorber and a superconducting transition-edge sensor. The absorber is high purity Sn and the transition-edge sensor is a Mo/Cu multilayer thin film. We have characterized the detector, and will discuss x-ray and gamma-ray results.

  19. Superconducting Properties of (Mx/YBa2Cu3O7-delta y)N Multilayer Films with Variable Layer Thickness x (Postprint)

    DTIC Science & Technology

    2012-02-01

    AFRL-RZ-WP-TP-2012-0132 SUPERCONDUCTING PROPERTIES OF (Mx/YBa2Cu3O7-δy)N MULTILAYER FILMS WITH VARIABLE LAYER THICKNESS x (POSTPRINT...April 2007 4. TITLE AND SUBTITLE SUPERCONDUCTING PROPERTIES OF (Mx/YBa2Cu3O7-δy)N MULTILAYER FILMS WITH VARIABLE LAYER THICKNESS x (POSTPRINT) 5a...effort was completed in 2007. Paper has color content. 14. ABSTRACT The superconducting properties of (Mx /YBa2Cu3O7-dy)N multilayer films were

  20. Miniaturized High-Temperature Superconducting/Dielectric Multilayer Filters for Satellite Communications

    NASA Technical Reports Server (NTRS)

    Miranda, Felix A.

    1997-01-01

    Most communication satellites contain well over a hundred filters in their payload. Current technology in typical satellite multiplexers use dual-mode cavity or dielectric resonator filters that are large (approx. 25 to 125 cu in) and heavy (up to 600 g). As the complexity of future advanced electronic systems for satellite communications increases, even more filters will be needed, requiring filter miniaturization without performance degradation. Such improvements in filter technology will enhance satellite performance. To reduce the size, weight, and cost of the multiplexers without compromising performance, the NASA Lewis Research Center is collaborating with industry to develop a new class of dual-mode multilayer filters consisting of YBa2Cu3O7-delta high-temperature superconducting (HTS) thin films on LaAlO3 substrates.

  1. Broadband sample holder for microwave spectroscopy of superconducting qubits

    SciTech Connect

    Averkin, A. S.; Karpov, A.; Glushkov, E.; Abramov, N.; Shulga, K.; Huebner, U.; Il'ichev, E.; Ustinov, A. V.

    2014-10-15

    We present a practical design and implementation of a broadband sample holder suitable for microwave experiments with superconducting integrated circuits at millikelvin temperatures. Proposed design can be easily integrated in standard dilution cryostats, has flat pass band response in a frequency range from 0 to 32 GHz, allowing the RF testing of the samples with substrate size up to 4 × 4 mm{sup 2}. The parasitic higher modes interference in the holder structure is analyzed and prevented via design considerations. The developed setup can be used for characterization of superconducting parametric amplifiers, bolometers, and qubits. We tested the designed sample holder by characterizing of a superconducting flux qubit at 20 mK temperature.

  2. Broadband sample holder for microwave spectroscopy of superconducting qubits.

    PubMed

    Averkin, A S; Karpov, A; Shulga, K; Glushkov, E; Abramov, N; Huebner, U; Il'ichev, E; Ustinov, A V

    2014-10-01

    We present a practical design and implementation of a broadband sample holder suitable for microwave experiments with superconducting integrated circuits at millikelvin temperatures. Proposed design can be easily integrated in standard dilution cryostats, has flat pass band response in a frequency range from 0 to 32 GHz, allowing the RF testing of the samples with substrate size up to 4 × 4 mm(2). The parasitic higher modes interference in the holder structure is analyzed and prevented via design considerations. The developed setup can be used for characterization of superconducting parametric amplifiers, bolometers, and qubits. We tested the designed sample holder by characterizing of a superconducting flux qubit at 20 mK temperature.

  3. Granular superconductivity and magnetic-field-driven recovery of macroscopic coherence in a cuprate/manganite multilayer

    NASA Astrophysics Data System (ADS)

    Mallett, B. P. P.; Khmaladze, J.; Marsik, P.; Perret, E.; Cerreta, A.; Orlita, M.; Biškup, N.; Varela, M.; Bernhard, C.

    2016-11-01

    We show that in Pr0.5La0.2Ca0.3MnO3 /YBa2Cu3O7 (PLCMO/YBCO) multilayers the low temperature state of YBCO is very resistive and resembles that of a granular superconductor or a frustrated Josephson-junction network. Notably, a coherent superconducting response can be restored with a large magnetic field which also suppresses the charge-orbital order in PLCMO. This coincidence suggests that the granular superconducting state of YBCO is induced by the charge-orbital order of PLCMO. The coupling mechanism and the nature of the induced inhomogeneous state in YBCO remain to be understood.

  4. Quantification of Multilayer Samples by Confocal {mu}XRF

    SciTech Connect

    Perez, R. Daniel; Sanchez, H. J.; Rubio, M.; Perez, C. A.

    2009-01-29

    The confocal setup consists of x-ray lenses in the excitation as well as in the detection channel. In this configuration, a micro volume defined by the overlap of the foci of both x-ray lenses is analyzed. Scanning this micro volume through the sample, 1-3 dimensional studies can be performed. For intermediate thin homogeneous layers a scanning in the normal direction to the surface sample provides information of its thickness and elemental composition. For multilayer samples it also provides the order of each layer in the stratified structure. For the confocal setup, we used a glass monocapillary in the excitation channel and a monolithic half polycapillary in the detection channel. The experiment was carried out at the D09B beamline of the LNLS using white beam. In the present work, a new algorithm was applied to analyze in detail by confocal {mu}XRF a sample of three paint layers on a glass substrate. Using the proposed algorithm, information about thickness and elemental densities was obtained for each layer of these samples.

  5. Transport currents measured in ring samples: test of superconducting weld

    NASA Astrophysics Data System (ADS)

    Zheng, H.; Claus, H.; Chen, L.; Paulikas, A. P.; Veal, B. W.; Olsson, B.; Koshelev, A.; Hull, J.; Crabtree, G. W.

    2001-02-01

    The critical current densities in bulk melt-textured YBa 2Cu 3O x and across superconducting “weld” joints are measured using scanning Hall probe measurements of the trapped magnetic field in ring samples. With this method, critical current densities are obtained without the use of electrical contacts. Large persistent currents are induced in ring samples at 77 K, after cooling in a 3 kG field. These currents can be determined from the magnetic field they produce. At 77 K a supercurrent exceeding 2000 A (about 10 4 A/cm 2) was induced in a 2 cm diameter ring; this current produces a magnetic field exceeding 1.5 kG in the bore of the ring. We demonstrate that when a ring is cut, and the cut is repaired by a superconducting weld, the weld joint can transmit the same high supercurrent as the bulk.

  6. Superconducting spin-valve effect and triplet superconductivity in Co Ox/Fe1/Cu /Fe2/Cu /Pb multilayer

    NASA Astrophysics Data System (ADS)

    Leksin, P. V.; Garif'yanov, N. N.; Kamashev, A. A.; Fominov, Ya. V.; Schumann, J.; Hess, C.; Kataev, V.; Büchner, B.; Garifullin, I. A.

    2015-06-01

    We report magnetic and superconducting properties of the modified spin-valve system CoOx/Fe1/Cu /Fe2/Cu /Pb . Introduction of a Cu interlayer between Fe2 and Pb layers prevents material interdiffusion process, increases the Fe2/Pb interface transparency, stabilizes and enhances properties of the system. This allowed us to perform a comprehensive study of such heterostructures and to present theoretical description of the superconducting spin-valve effect and of the manifestation of the long-range triplet component of the superconducting condensate.

  7. Thermal performance measurements of a 100 percent polyester MLI (multilayer insulation) system for the Superconducting Super Collider

    SciTech Connect

    Gonczy, J.D.; Boroski, W.N.; Niemann, R.C.

    1989-09-01

    The plastic materials used in the multilayer insulation (MLI) blankets of the superconducting magnets of the Superconducting Super Collider (SSC) are comprised entirely of polyesters. This paper reports on tests conducted in three separate experimental blanket arrangements. The tests explore the thermal performance of two candidate blanket joint configurations each employing a variation of a stepped-butted joint nested between sewn blanket seams. The results from the joint configurations are compared to measurements made describing the thermal performance of the basic blanket materials as tested in an ideal joint configuration. Twenty foil sensors were incorporated within each test blanket to measure interstitial layer and joint layer temperatures. Heat flux and thermal gradients are reported for high and degraded insulating vacuums, and during transient and steady state conditions. In complement with this paper is an associate paper bearing the same title head but with the title extension Part 1: Instrumentation and experimental preparation (300K-80K)'. 5 refs., 8 figs., 2 tabs.

  8. Automatic sequential fluid handling with multilayer microfluidic sample isolated pumping

    PubMed Central

    Liu, Jixiao; Fu, Hai; Yang, Tianhang; Li, Songjing

    2015-01-01

    To sequentially handle fluids is of great significance in quantitative biology, analytical chemistry, and bioassays. However, the technological options are limited when building such microfluidic sequential processing systems, and one of the encountered challenges is the need for reliable, efficient, and mass-production available microfluidic pumping methods. Herein, we present a bubble-free and pumping-control unified liquid handling method that is compatible with large-scale manufacture, termed multilayer microfluidic sample isolated pumping (mμSIP). The core part of the mμSIP is the selective permeable membrane that isolates the fluidic layer from the pneumatic layer. The air diffusion from the fluidic channel network into the degassing pneumatic channel network leads to fluidic channel pressure variation, which further results in consistent bubble-free liquid pumping into the channels and the dead-end chambers. We characterize the mμSIP by comparing the fluidic actuation processes with different parameters and a flow rate range of 0.013 μl/s to 0.097 μl/s is observed in the experiments. As the proof of concept, we demonstrate an automatic sequential fluid handling system aiming at digital assays and immunoassays, which further proves the unified pumping-control and suggests that the mμSIP is suitable for functional microfluidic assays with minimal operations. We believe that the mμSIP technology and demonstrated automatic sequential fluid handling system would enrich the microfluidic toolbox and benefit further inventions. PMID:26487904

  9. Effects of interlayer coupling on the magnetic and transport properties of superconducting multilayers and high-temperature superconductors

    SciTech Connect

    Gray, K.E.; Hettinger, J.D.; Kim, D.H.

    1994-06-01

    The effect of interlayer coupling on the transport properties and dissipation in a magnetic field is reviewed for superconducting multilayers including highly-anisotropic high-temperature superconductors (HTS). For the applied field parallel to the superconducting layers the absence of any Lorentz-force dependence of the dissipation leads to an explanation other than flux motion. This is consistent with a Josephson junction dissipation which dominates flux motion of the insulating regions between layers. However, in is seen to cross over from phase slips at Josephson junctions to depinning of vortices from the external field at high fields and temperatures. For fields perpendicular to the superconducting layers the much greater resistive broadening in HTS is due to dissipation by thermally-activated flux motion, consistent with a lack of intrinsic pinning. We show experimental evidence that the associated flux motion occurs as a result of a crossover from three dimensional (3D) vortex lines to 2D independent pancake-like vortices, residing in the Cu-O layers. This 3D to 2D crossover occurs after k{sub B}T exceeds the Josephson coupling energy.

  10. Investigating the Structural Bases of Voltage-Gating Model Channels by Using Perfectly Aligned Multilayer Samples

    DTIC Science & Technology

    1988-09-20

    UNLIMITED ] SAME AS RPT 0 DTIC USERS (U) 22a. NAME OF RESPONSIBLE INOIVIOUAL 22b TELEPHONE (Include Area Code) 22c. OFFICE SYMBOL Dr. Igor Vodyanoy 1 202-696...of gramicidin, alamethicin and melittin, and experimenting the variations of their chemical conditions. 2. Circular dichroism (CD) of multilayer...substrata are used depending on the type of experiment . The thickness of multilayers can be varied between 1 and 100 gi. The sample variables include

  11. High-temperature superconductivity in potassium-coated multilayer FeSe thin films.

    PubMed

    Miyata, Y; Nakayama, K; Sugawara, K; Sato, T; Takahashi, T

    2015-08-01

    The recent discovery of possible high-temperature (T(c)) superconductivity over 65 K in a monolayer FeSe film on SrTiO3 (refs 1-6) triggered a fierce debate on how superconductivity evolves from bulk to film, because bulk FeSe crystal exhibits a T(c) of no higher than 10 K (ref. 7). However, the difficulty in controlling the carrier density and the number of FeSe layers has hindered elucidation of this problem. Here, we demonstrate that deposition of potassium onto FeSe films markedly expands the accessible doping range towards the heavily electron-doped region. Intriguingly, we have succeeded in converting non-superconducting films with various thicknesses into superconductors with T(c) as high as 48 K. We also found a marked increase in the magnitude of the superconducting gap on decreasing the FeSe film thickness, indicating that the interface plays a crucial role in realizing the high-temperature superconductivity. The results presented provide a new strategy to enhance and optimize T(c) in ultrathin films of iron-based superconductors.

  12. A high-temperature superconducting delta-sigma modulator based on a multilayer technology with bicrystal Josephson junctions

    NASA Astrophysics Data System (ADS)

    Ruck, B.; Chong, Y.; Dittmann, R.; Engelhardt, A.; Sodtke, E.; Siegel, M.

    1999-11-01

    We have designed, fabricated and successfully tested a first-order delta-sigma modulator using a high-temperature superconducting multilayer technology with bicrystal Josephson junctions. The circuit has been fabricated on a SrTiO3 bicrystal substrate. The YBa2Cu3O7/SrTiO3/YBa2Cu3O7 trilayer was fabricated by laser deposition. The bottom layer served as a superconducting groundplane. The Josephson junctions were formed at the bicrystal line in the upper layer. The integrator resistance has been made from a Pd/Au thin film. The circuit consists of a dc-SFQ converter, a Josephson transmission line, a comparator, an L/R integrator and an output stage. The correct operation of the modulator has been tested using dc measurements. The linearity of the modulator was studied by measuring the harmonic distortions of a 19.5 kHz sine wave input signal. From the recorded spectrum, a minimum resolution of at least 5 bits can be estimated. This accuracy was limited by the noise of the preamplifier. The correct operation of the current feedback loop was demonstrated by cutting the feedback inductance.

  13. Superconductivity

    DTIC Science & Technology

    1989-07-01

    SUPERCONDUCTIVITY HIGH-POWER APPLICATIONS Electric power generation/transmission Energy storage Acoustic projectors Weapon launchers Catapult Ship propulsion • • • Stabilized...temperature superconductive shields could be substantially enhanced by use of high-Tc materials. 27 28 NRAC SUPERCONDUCTIVITY SHIP PROPULSION APPLICATIONS...motor shown in the photograph. As a next step in the evolution of electric-drive ship propulsion technology, DTRC has proposed to scale up the design

  14. Superconductivity

    NASA Astrophysics Data System (ADS)

    Yeo, Yung K.

    Many potential high-temperature superconductivity (HTS) military applications have been demonstrated by low-temperature superconductivity systems; they encompass high efficiency electric drives for naval vessels, airborne electric generators, energy storage systems for directed-energy weapons, electromechanical launchers, magnetic and electromagnetic shields, and cavity resonators for microwave and mm-wave generation. Further HST applications in militarily relevant fields include EM sensors, IR focal plane arrays, SQUIDs, magnetic gradiometers, high-power sonar sources, and superconducting antennas and inertial navigation systems. The development of SQUID sensors will furnish novel magnetic anomaly detection methods for ASW.

  15. A blanket design, apparatus, and fabrication techniques for the mass production of multilayer insulation blankets for the Superconducting Super Collider

    SciTech Connect

    Gonczy, J.D.; Boroski, W.N.; Niemann, R.C.; Otavka, J.G.; Ruschman, M.K.; Schoo, C.J.

    1989-09-01

    The multilayer insulation (MLI) system for the Superconducting Super Collider (SSC) consists of full cryostat length assemblies of aluminized polyester film fabricated in the form of blankets and installed as blankets to the 4.5K cold mass and the 20K and 80K thermal radiation shields. Approximately 40,000 MLI blankets will be required in the 10,000 cryogenic devices comprising the SSC accelerator. Each blanket is nearly 17 meters long and 1.8 meters wide. This paper reports the blanket design, an apparatus, and the fabrication method used to mass produce pre-fabricated MLI blankets. Incorporated in the blanket design are techniques which automate quality control during installation of the MLI blankets in the SSC cryostat. The apparatus and blanket fabrication method insure consistency in the mass produced blankets by providing positive control of the dimensional parameters which contribute to the thermal performance of the MLI blanket. By virtue of the fabrication process, the MLI blankets have inherent features of dimensional stability three-dimensional uniformity, controlled layer density, layer-to-layer registration, interlayer cleanliness, and interlayer material to accommodate thermal contraction differences. 11 refs., 6 figs., 1 tab.

  16. Thermal performance measurements of a 100 percent polyester MLI (multilayer insulation) system for the Superconducting Super Collider

    SciTech Connect

    Boroski, W.N.; Gonczy, J.D.; Niemann, R.C.

    1989-09-01

    Thermal performance measurements of a 100 percent polyester multilayer insulation (MLI) system for the Superconducting Super Collider (SSC) were conducted in a Heat Leak Test Facility (HLTF) under three experimental test arrangements. Each experiment measured the thermal performance of a 32-layer MLI blanket instrumented with twenty foil sensors to measure interstitial layer temperatures. Heat leak values and sensor temperatures were monitored during transient and steady state conditions under both design and degraded insulating vacuums. Heat leak values were measured using a heatmeter. MLI interstitial layer temperatures were measured using Cryogenic Linear Temperature Sensors (CLTS). Platinum resistors monitored system temperatures. High vacuum was measured using ion gauges; degraded vacuum employed thermocouple gauges. A four-wire system monitored instrumentation sensors and calibration heaters. An on-line computerized data acquisition system recorded and processes data. This paper reports on the instrumentation and experimental preparation used in carrying out these measurements. In complement with this paper is an associate paper bearing the same title head, but with the title extension Part 2: Laboratory results (300K--80K). 13 refs., 7 figs.

  17. Investigating the structural bases of voltage-gating model channels by using perfectly aligned multilayer samples

    NASA Astrophysics Data System (ADS)

    Huang, Huey W.

    1988-09-01

    One dimensional quasi crystals of perfect multilayers, in which ion channels are uniformly oriented within parallel membranes, can be used to study the structural base of channel conductivities. We have developed 1) the techniques for preparing such multilayer samples and 2) the spectroscopic methods (circular dichroism and x-ray diffraction) for extracting structural information from these samples. The sample variables include electric field, water content, ion concentrations, etc. We have observed conformation changes of alamethicin with water content, a result in favor of the barrel model (rather than the flip-flop model) for the channel. Our goal is to probe the conformation changes of the channels as we vary the sample variables, in order to elucidate the molecular mechanisms of voltage gating.

  18. High-Resolution Gamma-Ray Spectrometers using Bulk Absorbers Coupled to Mo/Cu Multilayer Superconducting Transition-Edge Sensors

    SciTech Connect

    Chow, D.T.; Loshak, A.; Van Den Berg, M.L.; Frank, M.; Barbee Jr., T.W.; Labov, S.E.

    2000-07-04

    In x-ray and gamma-ray spectroscopy, it is desirable to have detectors with high energy resolution and high absorption efficiency. At LLNL, we have developed superconducting tunnel junction-based single photon x-ray detectors with thin film absorbers that have achieved these goals for photon energies up to 1 keV. However, for energies above 1 keV, the absorption efficiency of these thin-film detectors decreases drastically. We are developing the use of high-purity superconducting bulk materials as microcalorimeter absorbers for high-energy x-rays and gamma rays. The increase in absorber temperature due to incident photons is sensed by a superconducting transition-edge sensor (TES) composed of a Mo/Cu multilayer thin film. Films of Mo and Cu are mutually insoluble and therefore very stable and can be annealed. The multilayer structure allows scaling in thickness to optimize heat capacity and normal state resistance. We measured an energy resolution of 70 eV for 60 keV incident gamma-rays with a 1 x 1 x 0.25 mm{sup 3} Sn absorber. We present x-ray and gamma-ray results from this detector design with a Sn absorber. We also propose the use of an active negative feedback voltage bias to improve the performance of our detector and show preliminary results.

  19. Calibration of tip and sample temperature of a scanning tunneling microscope using a superconductive sample

    SciTech Connect

    Stocker, Matthias; Pfeifer, Holger; Koslowski, Berndt

    2014-05-15

    The temperature of the electrodes is a crucial parameter in virtually all tunneling experiments. The temperature not only controls the thermodynamic state of the electrodes but also causes thermal broadening, which limits the energy resolution. Unfortunately, the construction of many scanning tunneling microscopes inherits a weak thermal link between tip and sample in order to make one side movable. Such, the temperature of that electrode is badly defined. Here, the authors present a procedure to calibrate the tip temperature by very simple means. The authors use a superconducting sample (Nb) and a standard tip made from W. Due to the asymmetry in the density of states of the superconductor (SC)—normal metal (NM) tunneling junction, the SC temperature controls predominantly the density of states while the NM controls the thermal smearing. By numerically simulating the I-V curves and numerically optimizing the tip temperature and the SC gap width, the tip temperature can be accurately deduced if the sample temperature is known or measureable. In our case, the temperature dependence of the SC gap may serve as a temperature sensor, leading to an accurate NM temperature even if the SC temperature is unknown.

  20. Superconductivity:

    NASA Astrophysics Data System (ADS)

    Sacchetti, N.

    In this paper a short historical account of the discovery of superconductivity and of its gradual development is given. The physical interpretation of its various aspects took about forty years (from 1911 to 1957) to reach a successful description of this phenomenon in terms of a microscopic theory At the very end it seemed that more or less everything could be reasonably interpreted even if modifications and refinements of the original theory were necessary. In 1986 the situation changed abruptly when a cautious but revolutionary paper appeared showing that superconductivity was found in certain ceramic oxides at temperatures above those up to then known. A rush of frantic experimental activity started world-wide and in less than one year it was shown that superconductivity is a much more widespread phenomenon than deemed before and can be found at temperatures well above the liquid air boiling point. The complexity and the number of the substances (mainly ceramic oxides) involved call for a sort of modern alchemy if compounds with the best superconducting properties are to be manufactured. We don't use the word alchemy in a deprecatory sense but just to emphasise that till now nobody can say why these compounds are what they are: superconductors.

  1. Characterization of electron microscopes with binary pseudo-random multilayer test samples

    SciTech Connect

    Yashchuk, Valeriy V; Conley, Raymond; Anderson, Erik H; Barber, Samuel K; Bouet, Nathalie; McKinney, Wayne R; Takacs, Peter Z; Voronov, Dmitriy L

    2010-09-17

    Verification of the reliability of metrology data from high quality x-ray optics requires that adequate methods for test and calibration of the instruments be developed. For such verification for optical surface profilometers in the spatial frequency domain, a modulation transfer function (MTF) calibration method based on binary pseudo-random (BPR) gratings and arrays has been suggested [Proc. SPIE 7077-7 (2007), Opt. Eng. 47(7), 073602-1-5 (2008)} and proven to be an effective calibration method for a number of interferometric microscopes, a phase shifting Fizeau interferometer, and a scatterometer [Nucl. Instr. and Meth. A 616, 172-82 (2010)]. Here we describe the details of development of binary pseudo-random multilayer (BPRML) test samples suitable for characterization of scanning (SEM) and transmission (TEM) electron microscopes. We discuss the results of TEM measurements with the BPRML test samples fabricated from a WiSi2/Si multilayer coating with pseudo randomly distributed layers. In particular, we demonstrate that significant information about the metrological reliability of the TEM measurements can be extracted even when the fundamental frequency of the BPRML sample is smaller than the Nyquist frequency of the measurements. The measurements demonstrate a number of problems related to the interpretation of the SEM and TEM data. Note that similar BPRML test samples can be used to characterize x-ray microscopes. Corresponding work with x-ray microscopes is in progress.

  2. Characterization of Electron Microscopes with Binary Pseudo-random Multilayer Test Samples

    SciTech Connect

    V Yashchuk; R Conley; E Anderson; S Barber; N Bouet; W McKinney; P Takacs; D Voronov

    2011-12-31

    Verification of the reliability of metrology data from high quality X-ray optics requires that adequate methods for test and calibration of the instruments be developed. For such verification for optical surface profilometers in the spatial frequency domain, a modulation transfer function (MTF) calibration method based on binary pseudo-random (BPR) gratings and arrays has been suggested [1] and [2] and proven to be an effective calibration method for a number of interferometric microscopes, a phase shifting Fizeau interferometer, and a scatterometer [5]. Here we describe the details of development of binary pseudo-random multilayer (BPRML) test samples suitable for characterization of scanning (SEM) and transmission (TEM) electron microscopes. We discuss the results of TEM measurements with the BPRML test samples fabricated from a WiSi2/Si multilayer coating with pseudo-randomly distributed layers. In particular, we demonstrate that significant information about the metrological reliability of the TEM measurements can be extracted even when the fundamental frequency of the BPRML sample is smaller than the Nyquist frequency of the measurements. The measurements demonstrate a number of problems related to the interpretation of the SEM and TEM data. Note that similar BPRML test samples can be used to characterize X-ray microscopes. Corresponding work with X-ray microscopes is in progress.

  3. Characterization of electron microscopes with binary pseudo-random multilayer test samples

    NASA Astrophysics Data System (ADS)

    Yashchuk, Valeriy V.; Conley, Raymond; Anderson, Erik H.; Barber, Samuel K.; Bouet, Nathalie; McKinney, Wayne R.; Takacs, Peter Z.; Voronov, Dmitriy L.

    2011-09-01

    Verification of the reliability of metrology data from high quality X-ray optics requires that adequate methods for test and calibration of the instruments be developed. For such verification for optical surface profilometers in the spatial frequency domain, a modulation transfer function (MTF) calibration method based on binary pseudo-random (BPR) gratings and arrays has been suggested [1,2] and proven to be an effective calibration method for a number of interferometric microscopes, a phase shifting Fizeau interferometer, and a scatterometer [5]. Here we describe the details of development of binary pseudo-random multilayer (BPRML) test samples suitable for characterization of scanning (SEM) and transmission (TEM) electron microscopes. We discuss the results of TEM measurements with the BPRML test samples fabricated from a WiSi 2/Si multilayer coating with pseudo-randomly distributed layers. In particular, we demonstrate that significant information about the metrological reliability of the TEM measurements can be extracted even when the fundamental frequency of the BPRML sample is smaller than the Nyquist frequency of the measurements. The measurements demonstrate a number of problems related to the interpretation of the SEM and TEM data. Note that similar BPRML test samples can be used to characterize X-ray microscopes. Corresponding work with X-ray microscopes is in progress.

  4. Characterization of electron microscopes with binary pseudo-random multilayer test samples

    SciTech Connect

    Yashchuk, V.V.; Conley, R.; Anderson, E.H.; Barber, S.K.; Bouet, N.; McKinney, W.R.; Takacs, P.Z. and Voronov, D.L.

    2010-12-08

    Verification of the reliability of metrology data from high quality X-ray optics requires that adequate methods for test and calibration of the instruments be developed. For such verification for optical surface profilometers in the spatial frequency domain, a modulation transfer function (MTF) calibration method based on binarypseudo-random (BPR) gratings and arrays has been suggested and and proven to be an effective calibration method for a number of interferometric microscopes, a phase shifting Fizeau interferometer, and a scatterometer. Here we describe the details of development of binarypseudo-random multilayer (BPRML) test samples suitable for characterization of scanning (SEM) and transmission (TEM) electron microscopes. We discuss the results of TEM measurements with the BPRML test samples fabricated from a WiSi{sub 2}/Si multilayer coating with pseudo-randomly distributed layers. In particular, we demonstrate that significant information about the metrological reliability of the TEM measurements can be extracted even when the fundamental frequency of the BPRML sample is smaller than the Nyquist frequency of the measurements. The measurements demonstrate a number of problems related to the interpretation of the SEM and TEM data. Note that similar BPRML testsamples can be used to characterize X-ray microscopes. Corresponding work with X-ray microscopes is in progress.

  5. Vortex quasi-crystals in mesoscopic superconducting samples

    NASA Astrophysics Data System (ADS)

    Wang, Jing-Kun; Zhang, Wei; R, Sá de Melo C. A.

    2016-08-01

    There seems to be a one to one correspondence between the phases of atomic and molecular matter (AMOM) and vortex matter (VM) in superfluids and superconductors. Crystals, liquids, and glasses have been experimentally observed in both AMOM and VM. Here, we propose a vortex quasi-crystal state which can be stabilized due to boundary and surface energy effects for samples of special shapes and sizes. For finite sized pentagonal samples, it is proposed that a phase transition between a vortex crystal and a vortex quasi-crystal occurs as a function of magnetic field and temperature as the sample size is reduced. Project supported by the National Natural Science Foundation of China (Grant Nos. 11274009, 11434011, and 111522436), the National Key Basic Research Program of China (Grant No. 2013CB922000), the Research Funds of Renmin University of China (Grant Nos. 10XNL016 and 16XNLQ03), and the Program of State Key Laboratory of Quantum Optics and Quantum Optics Devices (Grant No. KF201404).

  6. Training in test samples of superconducting cables for accelerator magnets

    SciTech Connect

    Ghosh, A.K.; Garber, M.; Robins, K.E.; Sampson, W.B.

    1988-08-22

    In the critical current measurement of some high current NbTi cables, the samples have to be ''trained'' by repeated quenching in order to obtain a usable voltage-current curve for I/sub c/ determination. This training behavior is most pronounced when the applied field is perpendicular to the wide face of the conductor and is strongly dependent on the copper-to-superconductor ratio and the clamping pressure. Data are given for SSC prototype cables as well as for HERA production conductors. Although a quantitative understanding of the experimental data is still lacking, some speculations regarding stability are presented. 8 refs., 7 figs.

  7. Disposable sample holder for high temperature measurements in MPMS superconducting quantum interference device magnetometers.

    PubMed

    Sesé, J; Bartolomé, J; Rillo, C

    2007-04-01

    A sample holder for high temperature (300 Ksuperconducting quantum interference device magnetometers is presented. It is fabricated using aluminum foil and it is appropriate for samples in either solid or powder form. The holder is homogeneous for the gradiometer coil, and this results in a contribution to the background signal that is below the instrument noise at any field (<10(-9) A m2 at mu(0)H=200 mT). Further it is inexpensive and simple to fabricate, and it can be considered as a disposable sample holder that avoids eventual contamination between different samples.

  8. Influence of sample width on the magnetoresistance and planar Hall effect of Co/Cu multilayers

    NASA Astrophysics Data System (ADS)

    C. Lima, S.; Baibich, M. N.

    2016-01-01

    We have studied Co/Cu multilayers to understand the effect of the sample's width on their magnetoresistance (MR). By keeping constant both the length and the thickness and exploring the widths within the range of usual magnetic domain sizes in those nanostructures, we were able to observe effects on the MR curve, as well as infer linked changes in the magnetization process. Associating MR and Planar Hall Effect (PHE) measurements, coupled to an analysis of the MR plots' symmetry, we were able to establish that, apart from the expected antiferromagnetic coupling, reducing the width forces the magnetization to stay aligned to the current channel, thus inducing more symmetric, closer to model Giant Magnetoresistance (GMR). Also, the sample edges might contribute by adding extra coupling through magnetostatic interaction. The added effects result in a counter-intuitive trend that goes from the near ideal wide samples through intermediate sizes with fairly abrupt changes in MR, and finally to the closer to bell-shaped ideal GMR at narrow widths.

  9. Calorimeters for precision power dissipation measurements on controlled-temperature superconducting radiofrequency samples.

    PubMed

    Xiao, B P; Reece, C E; Phillips, H L; Kelley, M J

    2012-12-01

    Two calorimeters, with stainless steel and Cu as the thermal path material for high precision and high power versions, respectively, have been designed and commissioned for the 7.5 GHz surface impedance characterization system at Jefferson Lab to provide low temperature control and measurement for CW power up to 22 W on a 5 cm diameter disk sample which is thermally isolated from the radiofrequency (RF) portion of the system. A power compensation method has been developed to measure the RF induced power on the sample. Simulation and experimental results show that with these two calorimeters, the whole thermal range of interest for superconducting radiofrequency materials has been covered. The power measurement error in the interested power range is within 1.2% and 2.7% for the high precision and high power versions, respectively. Temperature distributions on the sample surface for both versions have been simulated and the accuracy of sample temperature measurements have been analyzed. Both versions have the ability to accept bulk superconductors and thin film superconducting samples with a variety of substrate materials such as Al, Al(2)O(3), Cu, MgO, Nb, and Si.

  10. Calorimeters for Precision Power Dissipation Measurements on Controlled-Temperature Superconducting Radiofrequency Samples

    SciTech Connect

    Xiao, Binping P.; Kelley, Michael J.; Reece, Charles E.; Phillips, H. L.

    2012-12-01

    Two calorimeters, with stainless steel and Cu as the thermal path material for high precision and high power versions, respectively, have been designed and commissioned for the surface impedance characterization (SIC) system at Jefferson Lab to provide low temperature control and measurement for CW power up to 22 W on a 5 cm dia. disk sample which is thermally isolated from the RF portion of the system. A power compensation method has been developed to measure the RF induced power on the sample. Simulation and experimental results show that with these two calorimeters, the whole thermal range of interest for superconducting radiofrequency (SRF) materials has been covered. The power measurement error in the interested power range is within 1.2% and 2.7% for the high precision and high power versions, respectively. Temperature distributions on the sample surface for both versions have been simulated and the accuracy of sample temperature measurements have been analysed. Both versions have the ability to accept bulk superconductors and thin film superconducting samples with a variety of substrate materials such as Al, Al{sub 2}O{sub 3}, Cu, MgO, Nb and Si.

  11. Surface characterization of Nb samples electropolished together with real superconducting rf accelerator cavities

    SciTech Connect

    Xin Zhao; Geng, Rong -Li; Tyagi, P. V.; Hayano, Hitoshi; Kato, Shigeki; Nishiwaki, Michiru; Saeki, Takayuki; Sawabe, Motoaki

    2010-12-30

    Here, we report the results of surface characterizations of niobium (Nb) samples electropolished together with a single cell superconducting radio-frequency accelerator cavity. These witness samples were located in three regions of the cavity, namely at the equator, the iris and the beam-pipe. Auger electron spectroscopy (AES) was utilized to probe the chemical composition of the topmost four atomic layers. Scanning electron microscopy with energy dispersive X-ray for elemental analysis (SEM/EDX) was used to observe the surface topography and chemical composition at the micrometer scale. A few atomic layers of sulfur (S) were found covering the samples non-uniformly. Niobium oxide granules with a sharp geometry were observed on every sample. Some Nb-O granules appeared to also contain sulfur.

  12. Surface characterization of Nb samples electropolished together with real superconducting rf accelerator cavities

    DOE PAGES

    Xin Zhao; Geng, Rong -Li; Tyagi, P. V.; ...

    2010-12-30

    Here, we report the results of surface characterizations of niobium (Nb) samples electropolished together with a single cell superconducting radio-frequency accelerator cavity. These witness samples were located in three regions of the cavity, namely at the equator, the iris and the beam-pipe. Auger electron spectroscopy (AES) was utilized to probe the chemical composition of the topmost four atomic layers. Scanning electron microscopy with energy dispersive X-ray for elemental analysis (SEM/EDX) was used to observe the surface topography and chemical composition at the micrometer scale. A few atomic layers of sulfur (S) were found covering the samples non-uniformly. Niobium oxide granulesmore » with a sharp geometry were observed on every sample. Some Nb-O granules appeared to also contain sulfur.« less

  13. Double superconducting transition in the filled skutterudite PrOs4Sb12 and sample characterizations

    SciTech Connect

    Measson, M. A.; Braithwaite, D.; Lapertot, G.; Brison, J.P.; Flouquet, J.; Borded, P.; Sugawara, H.; Canfield, P.

    2008-04-23

    Through the characterization of many samples of the filled skutterudite compound PrOs4Sb12, we found that even though the double superconducting transition in the specific heat (Tc1 {approx}1.89 K and Tc2 {approx} 1.72 K) appears in samples of good quality, there are various pieces of evidence that cast doubt on its intrinsic nature. First, three samples exhibit a single sharp transition of {approx}15 mK width at Tc{approx}1.7 K. The quality of the samples exhibiting a single transition is clearly better; the width of the transition is smallest and the normalized specific heat jump ((C-Cnormal)/Cnormal)Tc is larger than the sum of the two specific heat jumps when a double transition exists. Second, the ratio of the two specific heat jumps Delta C(Tc1)/Delta C(Tc2) exhibits a wide variation with samples not only among different batches but also even within a batch. Finally, this ratio was strongly reduced by polishing a sample down to {approx}100 {micro}m, which points to bulk inhomogeneities as an origin of the spurious transition. Our x-ray diffraction analysis points to Pr-vacancy problem in the samples, but it does not show that they are the origin of the double transition. We provide the superconducting phase diagram under magnetic field of a sample exhibiting a single transition and fit the curve Hc2(T) with a two-band model taking into account the appropriate values for the gap as deduced from thermal conductivity measurements.

  14. Micro-Vibration Measurements on Thermally Loaded Multi-Layer Insulation Samples in Vacuum

    NASA Technical Reports Server (NTRS)

    Deutsch, Georg; Grillenbeck, Anton

    2008-01-01

    Some scientific missions require to an extreme extent the absence of any on-board microvibration. Recent projects dedicated to measuring the Earth's gravity field and modeling the geoid with extremely high accuracy are examples. Their missions demand for extremely low micro-vibration environment on orbit for: (1) Not disturbing the measurement of earth gravity effects with the installed gradiometer or (2) Even not damaging the very high sensitive instruments. Based on evidence from ongoing missions multi-layer insulation (MLI) type thermal control blankets have been identified as a structural element of spacecrafts which might deform under temperature variations being caused by varying solar irradiation in orbit. Any such deformation exerts tiny forces which may cause small reactions resulting in micro-vibrations, in particular by exciting the spacecraft eigenmodes. The principle of the test set-up for the micro-vibration test was as follows. A real side wall panel of the spacecraft (size about 0.25 m2) was low-frequency suspended in a thermal vacuum chamber. On the one side of this panel, the MLI samples were fixed by using the standard methods. In front of the MLI, an IR-rig was installed which provided actively controlled IR-radiation power of about 6 kW/m2 in order to heat the MLI surface. The cooling was passive using the shroud temperature at a chamber pressure <1E-5mbar. The resulting micro-vibrations due to MLI motion in the heating and the cooling phase were measured via seismic accelerometers which were rigidly mounted to the panel. Video recording was used to correlate micro-vibration events to any visual MLI motion. Different MLI sample types were subjected to various thermal cycles in a temperature range between -60 C to +80 C. In this paper, the experience on these micro-vibration measurements will be presented and the conclusions for future applications will be discussed

  15. Multilayered samples reconstructed by measuring Kα/Kβ or Lα/Lβ X-ray intensity ratios by EDXRF

    NASA Astrophysics Data System (ADS)

    Cesareo, Roberto; de Assis, Joaquim T.; Roldán, Clodoaldo; Bustamante, Angel D.; Brunetti, Antonio; Schiavon, Nick

    2013-10-01

    In this paper a general method based on energy-dispersive X-ray fluorescence (EDXRF) analysis has been tested to assess its possible use as a tool to reconstruct the structure and determine the thickness of two and/or multi-layered materials. The method utilizes the X-ray intensity ratios of Kα/Kβ or Lα/Lβ peaks (or the ratio of these peaks) for selected elements present in multi-layered objects of various materials (Au alloys, gilded Cu, gilded Ag, gilded Pb, Ag-Au Tumbaga, stone surfaces with protective treatments, Zn or Nickel plating on metals). Results show that, in the case of multi-layered samples, a correct calculation of the peak ratio (Kα /Kβ and/or Lα/Lβ) of relevant elements from energy-dispersive X-ray fluorescence spectra, can provide important information in assessing the exact location of each layer and for calculating its thickness. The methodological approach shown may have important applications not only in materials science but also when dealing with the conservation and restoration of multi-layered cultural heritage objects where the use of a Non-Destructive techniques to determine slight chemical and thickness variations in the layered structure is often of paramount importance to achieve the best results.

  16. Development of a Compact Moving-Sample Magnetometer Using High-Tc Superconducting Quantum Interference Device

    NASA Astrophysics Data System (ADS)

    Mawardi Saari, Mohd; Sakai, Kenji; Kiwa, Toshihiko; Tsukamoto, Akira; Adachi, Seiji; Tanabe, Keiichi; Kandori, Akihiko; Tsukada, Keiji

    2012-04-01

    We developed a compact moving-sample magnetometer that uses a high-temperature superconductor-superconducting quantum interference device (high-Tc SQUID) to directly measure the flux coupled to a normal detection coil from a sample's magnetic moment in the presence of an external DC magnetic field. The moving-sample method is employed by inserting the sample between the poles of a DC electromagnet and vibrating the sample along the axis perpendicular to the external field axis using an actuator at a frequency of 2.693 Hz. First, the magnetic field of the sample is transferred by a first-order differential normal Cu coil to a SQUID for detection. Then, the SQUID output is fed to a lock-in amplifier for detection. The critical feature of the system design is the use of high-Tc SQUID, which enables the realization of a compact system. The basic characteristics of the developed system are presented, and the current system exhibited a detection limit of 1×10-7 emu.

  17. Development of a Compact Moving-Sample Magnetometer Using High-Tc Superconducting Quantum Interference Device

    NASA Astrophysics Data System (ADS)

    Saari, Mohd Mawardi; Sakai, Kenji; Kiwa, Toshihiko; Tsukamoto, Akira; Adachi, Seiji; Tanabe, Keiichi; Kandori, Akihiko; Tsukada, Keiji

    2012-04-01

    We developed a compact moving-sample magnetometer that uses a high-temperature superconductor--superconducting quantum interference device (high-Tc SQUID) to directly measure the flux coupled to a normal detection coil from a sample's magnetic moment in the presence of an external DC magnetic field. The moving-sample method is employed by inserting the sample between the poles of a DC electromagnet and vibrating the sample along the axis perpendicular to the external field axis using an actuator at a frequency of 2.693 Hz. First, the magnetic field of the sample is transferred by a first-order differential normal Cu coil to a SQUID for detection. Then, the SQUID output is fed to a lock-in amplifier for detection. The critical feature of the system design is the use of high-Tc SQUID, which enables the realization of a compact system. The basic characteristics of the developed system are presented, and the current system exhibited a detection limit of 1× 10-7 emu.

  18. Method for determining temperatures and heat transfer coefficients with a superconductive sample

    SciTech Connect

    Gentile, D.; Hassenzahl, W.; Polak, M.

    1980-05-01

    The method that is described here uses the current-sharing characteristic of a copper-stabilized, superconductive NbTi wire to determine the temperature. The measurements were made for magnetic fields up to 6 T and the precision actually attained with this method is about 0.1 K. It is an improvement over one that has been used at 4.2 K to measure transient heat transfer in that all the parameters of the sample are well known and the current in the sample is measured directly. The response time of the probe is less than 5 ..mu..s and it has been used to measure temperatures during heat pulses as short as 20 ..mu..s. Temperature measurements between 1.6 and 8.5 K are described. An accurate formula based on the current and electric field along the sample has been developed for temperatures between 2.5 K and the critical temperature of the conductor, which, of course, depends on the applied field. Also described is a graphical method that must be used below 2.5 K, where the critical current is not a linear function of temperature.

  19. Surface analyses of electropolished niobium samples for superconducting radio frequency cavity

    SciTech Connect

    Tyagi, P. V.; Nishiwaki, M.; Saeki, T.; Sawabe, M.; Hayano, H.; Noguchi, T.; Kato, S.

    2010-07-15

    The performance of superconducting radio frequency niobium cavities is sometimes limited by contaminations present on the cavity surface. In the recent years extensive research has been done to enhance the cavity performance by applying improved surface treatments such as mechanical grinding, electropolishing (EP), chemical polishing, tumbling, etc., followed by various rinsing methods such as ultrasonic pure water rinse, alcoholic rinse, high pressure water rinse, hydrogen per oxide rinse, etc. Although good cavity performance has been obtained lately by various post-EP cleaning methods, the detailed nature about the surface contaminants is still not fully characterized. Further efforts in this area are desired. Prior x-ray photoelectron spectroscopy (XPS) analyses of EPed niobium samples treated with fresh EP acid, demonstrated that the surfaces were covered mainly with the niobium oxide (Nb{sub 2}O{sub 5}) along with carbon, in addition a small quantity of sulfur and fluorine were also found in secondary ion mass spectroscopy (SIMS) analysis. In this article, the authors present the analyses of surface contaminations for a series of EPed niobium samples located at various positions of a single cell niobium cavity followed by ultrapure water rinsing as well as our endeavor to understand the aging effect of EP acid solution in terms of contaminations presence at the inner surface of the cavity with the help of surface analytical tools such as XPS, SIMS, and scanning electron microscope at KEK.

  20. Study of vortex states and dynamics in mesoscopic superconducting samples with MFM

    NASA Astrophysics Data System (ADS)

    Polshyn, Gregory; Naibert, Tyler; Chua, Victor; Budakian, Raffi

    Vortex states in superconducting (SC) structures, their dynamics and ways to manipulate them are topics of great interest. We report a new method of magnetic force microscopy (MFM) that allows the study of vortex states in mesoscopic SC samples. For the case of a SC ring, which is biased to a half-integer flux quantum, the flux modulation through the ring caused by the motion of the magnetic tip drives the ring between two consecutive fluxoid states. The corresponding current switching in the ring produces strong position-dependent forces on the cantilever. In the regime where the frequency of the thermally activated jumps between fluxoid states is close to the frequency of the cantilever, large changes in the cantilever frequency and dissipation are observed. This effect may be understood as a stochastic resonance (SR) process. These changes in the cantilever's mechanical properties are used to ``image'' the barrier energies between fluxoid states. Additionally, SR imaging of the barrier energies are used to study the effect of the locally applied magnetic field from the MFM tip on the barrier heights. We report the results of measurements for Al rings. Further, the same imaging technique can be applied to more sophisticated SC structures such as arrays of Josephson junctions.

  1. Study on effect of annealing conditions on structural, magnetic and superconducting properties of MgB{sub 2} bulk samples

    SciTech Connect

    Phaneendra, Konduru Asokan, K. Kanjilal, D.; Awana, V. P. S.; Sastry, S. Sreehari

    2014-04-24

    Effect of annealing conditions on structural, magnetic and superconducting properties of Magnesium Diboride (MgB{sub 2}) bulk superconductor samples prepared by solid state route method are compared. The samples are made by taking Magnesium and Boron powders in stoichiometric ratio, grounded well and pelletized at pressure of about 10Tonnes. These pellets are annealed in both Argon and vacuum environment separately up to 800°c for two hours. Both the samples show clear superconducting transition at Tc ∼ 38 k. This is further conformed by AC/DC magnetization (M-T), Resistivity [ρ (T, H)] measurements under magnetic field up to 14 Tesla as well. Rietveld refinement of X-ray diffraction of both samples conformed the MgB{sub 2} phase formation with P6/mmm space group symmetry. Scanning Electron Microscopy images of the surface revile more agglomeration of grains in case of Argon annealed samples. This result in more critical current density (J{sub c}) of Argon annealed samples than vacuum annealed one calculated from Bean's critical state model. This high Jc is explained in terms of more inter grain connectivity for Argon annealed sample than vacuum annealed sample.

  2. Precise in situ etch depth control of multilayered III−V semiconductor samples with reflectance anisotropy spectroscopy (RAS) equipment

    PubMed Central

    Kleinschmidt, Ann-Kathrin; Barzen, Lars; Strassner, Johannes; Doering, Christoph; Bock, Wolfgang; Wahl, Michael; Kopnarski, Michael

    2016-01-01

    Reflectance anisotropy spectroscopy (RAS) equipment is applied to monitor dry-etch processes (here specifically reactive ion etching (RIE)) of monocrystalline multilayered III–V semiconductors in situ. The related accuracy of etch depth control is better than 16 nm. Comparison with results of secondary ion mass spectrometry (SIMS) reveals a deviation of only about 4 nm in optimal cases. To illustrate the applicability of the reported method in every day settings for the first time the highly etch depth sensitive lithographic process to form a film lens on the waveguide ridge of a broad area laser (BAL) is presented. This example elucidates the benefits of the method in semiconductor device fabrication and also suggests how to fulfill design requirements for the sample in order to make RAS control possible. PMID:28144528

  3. Low frequency magneto-impedance effects in electrode-posited multilayer [Ni80Fe20/Cu]3 on Cu-wire substrates with different sample geometry

    NASA Astrophysics Data System (ADS)

    Wicaksono, B. Anggit; Nahrun, Ahmad Asrori; Nuryani, Purnama, Budi

    2016-02-01

    Magneto-impedance (MI) multilayer [Ni80Fe20 (800 nm)/Cu (300 nm)]3 in Cu wire has been modified in its geometric shapes. The Multilayer is the result of electro-deposition with Pt (platinum) as the electrode. This study shows that the MI ratio changes to the geometry of the sample. The geometry modification increases the MI ratio of 54.35% (wire shape) amounted to 70.53% (solenoid shape); it is measured at a frequency of 100 kHz. The modification also increase the sensitivity sensor magnetic from 9.05%/mT to 12.82%/mT.

  4. Versatile pulsed laser setup for depth profiling analysis of multilayered samples in the field of cultural heritage

    NASA Astrophysics Data System (ADS)

    Mendes, N. F. C.; Osticioli, I.; Striova, J.; Sansonetti, A.; Becucci, M.; Castellucci, E.

    2009-04-01

    The present study considers the use of a nanosecond pulsed laser setup capable of performing laser induced breakdown spectroscopy (LIBS) and pulsed Raman spectroscopy for the study of multilayered objects in the field of cultural heritage. Controlled etching using the 4th harmonic 266 nm emission of a Nd:YAG laser source with a 8 ns pulse duration was performed on organic films and mineral strata meant to simulate different sequence of layers usually found in art objects such as in easel and mural paintings. The process of micro ablation coupled with powerful spectroscopic techniques operating with the same laser source, constitutes an interesting alternative to mechanical sampling especially when dealing with artworks such as ceramics and metal works which are problematic due to their hardness and brittleness. Another case is that of valuable pieces where sampling is not an option and the materials to analyse lie behind the surface. The capabilities and limitations of such instrumentation were assessed through several tests in order to characterize the trend of the laser ablation on different materials. Monitored ablation was performed on commercial sheets of polyethylene terephthalate (PET), a standard material of known thickness and mechanical stability, and rabbit glue, an adhesive often used in works of art. Measurements were finally carried out on a specimen with a stratigraphy similar to those found in real mural paintings.

  5. Characterization of electron microscopes with binary pseudo-random multilayer test samples

    SciTech Connect

    Yashchuk, Valeriy V; Conley, Raymond; Anderson, Erik H.; Barber, Samuel K.; Bouet, Nathalie; McKinney, Wayne R.; Takacs, Peter Z.; Voronov, Dmitriy L.

    2010-07-09

    We discuss the results of SEM and TEM measurements with the BPRML test samples fabricated from a BPRML (WSi2/Si with fundamental layer thickness of 3 nm) with a Dual Beam FIB (focused ion beam)/SEM technique. In particular, we demonstrate that significant information about the metrological reliability of the TEM measurements can be extracted even when the fundamental frequency of the BPRML sample is smaller than the Nyquist frequency of the measurements. The measurements demonstrate a number of problems related to the interpretation of the SEM and TEM data. Note that similar BPRML test samples can be used to characterize x-ray microscopes. Corresponding work with x-ray microscopes is in progress.

  6. Decoherence and interferometric sensitivity of boson sampling in superconducting resonator networks

    NASA Astrophysics Data System (ADS)

    Goldstein, Samuel; Korenblit, Simcha; Bendor, Ydan; You, Hao; Geller, Michael R.; Katz, Nadav

    2017-01-01

    Multiple bosons undergoing coherent evolution in a coupled network of sites constitute a so-called quantum walk system. The simplest example of such a two-particle interference is the celebrated Hong-Ou-Mandel interference. When scaling to larger boson numbers, simulating the exact distribution of bosons has been shown, under reasonable assumptions, to be exponentially hard. We analyze the feasibility and expected performance of a globally connected superconducting resonator based quantum walk system, using the known characteristics of state-of-the-art components. We simulate the sensitivity of such a system to decay processes and to perturbations and compare with coherent input states.

  7. Multilayer pinning in a-axis-oriented EuBa2Cu3O7/PrBa2Cu3O7 superconducting superlattices

    NASA Astrophysics Data System (ADS)

    Martin, J. I.; Velez, M.; Vicent, J. L.

    1995-08-01

    a-axis EuBa2Cu3O7/PrBa2Cu3O7 superlattices and a-axis films have been grown by dc sputtering to study the interplay between the natural material anisotropy (Cu-O planes) and the artificial layered structure (PrBa2Cu3O7 layers). These a-axis-oriented superlattices are unique because, in comparison with c-axis superlattices, they allow one to separate both effects: in c-axis multilayers Cu-O planes and the artificial layers are parallel whereas in a-axis multilayers the intrinsic and the artificial layers are perpendicular to each other. When B is parallel to the substrate plane, the superlattices show an enhancement of the pinning force in comparison with the behavior of the films that is controlled by the EuBa2Cu3O7 layer thickness. If B is perpendicular to the substrate plane, the flux motion presents a log B dependence of the activation energy up to at least, 40-unit-cell-thick layers.

  8. Unusual layer-dependent charge distribution, collective mode coupling, and superconductivity in multilayer cuprate Ba2Ca3Cu4O8F2.

    PubMed

    Chen, Yulin; Iyo, Akira; Yang, Wanli; Ino, Akihiro; Arita, M; Johnston, Steve; Eisaki, Hiroshi; Namatame, H; Taniguchi, M; Devereaux, Thomas P; Hussain, Zahid; Shen, Z-X

    2009-07-17

    Low energy ultrahigh momentum resolution angle resolved photoemission spectroscopy study on four-layer self-doped high Tc superconductor Ba2Ca3Cu4O8F2 (F0234) revealed fine structure in the band dispersion, identifying the unconventional association of hole and electron doping with the inner and outer CuO2 layers, respectively. For the states originating from two inequivalent CuO2 layers, different energy scales are observed in dispersion kinks associated with the collective mode coupling, with the larger energy scale found in the electron (n-) doped state which also has stronger coupling strength. Given the earlier finding that the superconducting gap is substantially larger along the n-type Fermi surface, our observations connect the mode coupling energy and strength with magnitude of the pairing gap.

  9. Unusual Layer-Dependent Charge Distribution, Collective Mode Coupling, and Superconductivity in Multilayer Cuprate Ba2Ca3Cu4O8F2

    SciTech Connect

    Chen, Yulin; Iyo, Akira; Yang, Wanli; Ino, Akihiro; Arita, M.; Johnston, Steve; Eisaki, Hiroshi; Namatame, H.; Taniguchi, M.; Devereaux, Thomas P.; Hussain, Zahid; Shen, Z.-X.; /SLAC /Stanford U., Phys. Dept.

    2011-08-12

    Low energy ultrahigh momentum resolution angle resolved photoemission spectroscopy study on four-layer self-doped high T{sub c} superconductor Ba{sub 2}Ca{sub 3}Cu{sub 4}O{sub 8}F{sub 2} (F0234) revealed fine structure in the band dispersion, identifying the unconventional association of hole and electron doping with the inner and outer CuO{sub 2} layers, respectively. For the states originating from two inequivalent CuO{sub 2} layers, different energy scales are observed in dispersion kinks associated with the collective mode coupling, with the larger energy scale found in the electron (n-) doped state which also has stronger coupling strength. Given the earlier finding that the superconducting gap is substantially larger along the n-type Fermi surface, our observations connect the mode coupling energy and strength with magnitude of the pairing gap.

  10. Characterization Of Superconducting Samples With SIC System For Thin Film Developments: Status And Recent Results

    SciTech Connect

    Phillips, H. Lawrence; Reece, Charles E.; Valente-Feliciano, Anne-Marie; Xiao, Binping; Eremeev, Grigory V.

    2014-02-01

    Within any thin film development program directed towards SRF accelerating structures, there is a need for an RF characterization device that can provide information about RF properties of small samples. The current installation of the RF characterization device at Jefferson Lab is Surface Impedance Characterization (SIC) system. The data acquisition environment for the system has recently been improved to allow for automated measurement, and the system has been routinely used for characterization of bulk Nb, films of Nb on Cu, MgB{sub 2}, NbTiN, Nb{sub 3}Sn films, etc. We present some of the recent results that illustrate present capabilities and limitations of the system.

  11. Magnetic multilayer interface anisotropy

    SciTech Connect

    Pechan, M.J.

    1990-01-01

    Ni/Mo and Ni/V multilayer magnetic anisotropy has been investigated as a function of Ni layer thickness, frequency and temperature. Variable frequency ferromagnetic resonance (FMR) measurements show, for the first time, significant frequency dependence associated with the multilayer magnetic anisotropy. The thickness dependence allows one to extract the interface contribution from the total anisotropy. Temperature dependent FMR (9 GHz) and room temperature magnetization indicate that strain between Ni and the non-magnetic layers is contributing significantly to the source of the interface anisotropy and the state of the interfacial magnetization. In order to examine the interface properties of other transition metal multilayer systems, investigations on Fe/Cu are underway and CoCr/Ag is being proposed. ESR measurements have been reported on Gd substituted YBaCuO superconductors and a novel quasi-equilibrium method has been developed to determine quickly and precisely the transition temperature. During the next project period the P.I. proposes to (1) extend the variable frequency FMR measurements to low temperature, where extremely large interface anisotropies are known to obtain in Ni/Mo and Ni/V and are proposed to exist in Ni/W; (2) obtain accurate dc anisotropies via a novel, variable temperature torque magnetometer currently under construction; (3) expand upon his initial findings in Fe/Cu multilayer investigations; (4) begin anisotropy investigations on Co/Ag and CoCr/Ag multilayers where the easy magnetization direction depends upon the Cr concentration; (4) make and characterize Bi based superconductors according to resistivity, thermal conductivity and thermoelectric power and construct YBaCuO based superconducting loop-gap'' resonators for use in his magnetic resonance work.

  12. Magnetic multilayer interface anisotropy

    SciTech Connect

    Pechan, M.J.

    1991-01-01

    Ni/Mo and Ni/V multilayer magnetic anisotropy has been investigated as a function of Ni layer thickness, frequency and temperature. Variable frequency ferromagnetic resonance (FMR) measurements show, for the first time, significant frequency dependence associated with the multilayer magnetic anisotropy. The thickness dependence allows one to extract the interface contribution from the total anisotropy. Temperature dependant FMR (9 GHz) and room temperature magnetization indicate that strain between Ni and the non-magnetic layers if contributing significantly to the source of the interface anisotropy and the state of the interfacial magnetization. In order to examine the interface properties of other transition metal multilayer systems, investigations on Fe/Cu are underway and CoCr/Ag is being proposed. ESR measurements have been reported on Gd substituted YBaCuO superconductors and a novel quasi-equilibrium method has been developed to determine quickly and precisely the transition temperature. During the next project the P.I. proposes to (1) extend the variable frequency FMR measurements to low temperature, where extremely large interface anisotropies are known to obtain in Ni/Mo and Ni/V and are proposed to exist in Ni/W; (2) obtain accurate dc anisotropies via a novel, variable temperature torque magnetometer currently under construction; (3) expand upon his initial findings in Fe/Cu multilayer investigations; (4) begin anisotropy investigations on Co/Ag and CoCr/Ag multilayers where the easy magnetization direction depends upon the Cr concentration; (4) make and characterize Bi based superconductors according to resistivity, thermal conductivity and thermoelectric power and construct YBaCuO based superconducting loop-gap'' resonators for use in his magnetic resonance work. 2 figs.

  13. The superconducting spin valve and triplet superconductivity

    NASA Astrophysics Data System (ADS)

    Garifullin, I. A.; Leksin, P. V.; Garif`yanov, N. N.; Kamashev, A. A.; Fominov, Ya. V.; Schumann, J.; Krupskaya, Y.; Kataev, V.; Schmidt, O. G.; Büchner, B.

    2015-01-01

    A review of our recent results on the spin valve effect is presented. We have used a theoretically proposed spin switch design F1/F2/S comprising a ferromagnetic bilayer (F1/F2) as a ferromagnetic component, and an ordinary superconductor (S) as the second interface component. Based on it we have prepared and studied in detail a set of multilayers CoOx/Fe1/Cu/Fe2/S (S=In or Pb). In these heterostructures we have realized for the first time a full spin switch effect for the superconducting current, have observed its sign-changing oscillating behavior as a function of the Fe2-layer thickness and finally have obtained direct evidence for the long-range triplet superconductivity arising due to noncollinearity of the magnetizations of the Fe1 and Fe2 layers.

  14. MULTI-LAYER SAMPLING IN CONVENTIONAL MONITORING WELLS FOR IMPROVED ESTIMATION OF VERTICAL CONTAMINANT DISTRIBUTIONS AND MASS

    EPA Science Inventory

    "Traditional" approaches to sampling groundwater and interpreting monitoring well data often provide misleading pictures of plume shape and location in the subsurface and the true extent of contamination. Groundwater samples acquired using pumps and bailers in conventional monito...

  15. Superconducting Thin Films for SRF Cavity Applications: A Route to Higher Field Gradient Linacs

    NASA Astrophysics Data System (ADS)

    Roach, Wiliam Michael

    Many linear accelerator (linac) applications rely on the use of superconducting radio frequency (SRF) cavities. In order to overcome the current field gradient limits imposed by the use of bulk niobium, a model involving the deposition of alternating superconducting-insulating-superconducting (SIS) thin films onto the interior surface of SRF cavities has been proposed. Since SRF performance is a surface phenomenon, the critical surface of these cavities is less than 1 micron thick, thus enabling the use of thin films. Before such approach can successfully be implemented fundamental studies correlating the microstructure and superconducting properties of thin films are needed. To this end the effect of grain boundary density and interfacial strain in thin films has been explored. Thin films with a smaller grain boundary density were found to have better superconducting properties than films with a larger grain boundary density. Interfacial strain due to a lattice mismatch between the film and substrate lead to two regions in films, one strained region near the interface and one relaxed region away from the interface. The presence of two regions in the film resulted in two types of superconducting behavior. Niobium films were deposited onto copper surfaces to help understand why previous attempts of implementing niobium coated copper cavities in order to exploit the better thermal properties of copper had varying degrees of success. It was found that an increased growth temperature produced niobium films with larger grains and correspondingly better superconducting properties. Proof of principle multilayer samples were prepared to test the SIS model. For the first time, multilayers were produced that were capable of shielding an underlying niobium film from vortex penetration beyond the lower critical field of bulk niobium. This result provides evidence supporting the feasibility of the SIS model.

  16. Modeling multilayer woven fabrics

    NASA Astrophysics Data System (ADS)

    Åström, J. A.; Mäkinen, J. P.; Timonen, J.

    2001-07-01

    A numerical algorithm for nonlinear elastic relaxation of a multilayer woven fabric is introduced and tested. The equilibrium solutions are compared with real samples. An excellent result is obtained in spite of two simplifications: Bending stiffness of the fibers and friction between the fibers are both neglected. The numerical simulation is very fast and cost efficient in the search for optimal fabrics.

  17. Increasing the sensitivity of the spectrophotometric determinations of the oxygen content in YBCO superconducting samples using the I(3-)-starch compound.

    PubMed

    Nedeltcheva, Tsvetanka K; Georgieva, Stela Iv; Vladimirova, Latinka K; Stoyanova-Ivanova, Angelina K

    2009-03-15

    The conditions for formation of the I(3)(-)-starch compound and measuring its absorbance have been found, and a spectrophotometric method has been developed for the determination of the oxygen content in YBa(2)Cu(3)O(y) superconducting bulk samples. The method involves the following stages: a decomposition of the sample in an acid medium in the presence of iodide ions under inert atmosphere; formation of a complex between Cu(II) and glycine; binding the I(3)(-)-complex with a starch and the absorbance measurement of the colored I(3)(-)-starch compound. The coefficient of the active oxygen is calculated by the ratio of the absorbances of two solutions and the method does not require both calibration and precise measuring sample mass. The accuracy of the results is confirmed applying the comparative spectrophotometric method that uses the yellow I(3)(-)-complex. The precision of the results evaluated by the relative standard deviation is 2%. The developed method is sensitive and allows a sample mass about 2mg to be used. The analysis is rapid and requires a simple and inexpensive apparatus. Thus the new method would be useful for an express analytical control of the oxygen content of YBCO-superconducting materials produced for the electronics.

  18. High temperature interface superconductivity

    NASA Astrophysics Data System (ADS)

    Gozar, A.; Bozovic, I.

    2016-02-01

    High-Tc superconductivity at interfaces has a history of more than a couple of decades. In this review we focus our attention on copper-oxide based heterostructures and multi-layers. We first discuss the technique, atomic layer-by-layer molecular beam epitaxy (ALL-MBE) engineering, that enabled High-Tc Interface Superconductivity (HT-IS), and the challenges associated with the realization of high quality interfaces. Then we turn our attention to the experiments which shed light on the structure and properties of interfacial layers, allowing comparison to those of single-phase films and bulk crystals. Both 'passive' hetero-structures as well as surface-induced effects by external gating are discussed. We conclude by comparing HT-IS in cuprates and in other classes of materials, especially Fe-based superconductors, and by examining the grand challenges currently laying ahead for the field.

  19. High temperature interface superconductivity

    DOE PAGES

    Gozar, A.; Bozovic, I.

    2016-01-20

    High-Tc superconductivity at interfaces has a history of more than a couple of decades. In this review we focus our attention on copper-oxide based heterostructures and multi-layers. We first discuss the technique, atomic layer-by-layer molecular beam epitaxy (ALL-MBE) engineering, that enabled High-Tc Interface Superconductivity (HT-IS), and the challenges associated with the realization of high quality interfaces. Then we turn our attention to the experiments which shed light on the structure and properties of interfacial layers, allowing comparison to those of single-phase films and bulk crystals. Both ‘passive’ hetero-structures as well as surface-induced effects by external gating are discussed. Here, wemore » conclude by comparing HT-IS in cuprates and in other classes of materials, especially Fe-based superconductors, and by examining the grand challenges currently laying ahead for the field.« less

  20. High temperature interface superconductivity

    SciTech Connect

    Gozar, A.; Bozovic, I.

    2016-01-20

    High-Tc superconductivity at interfaces has a history of more than a couple of decades. In this review we focus our attention on copper-oxide based heterostructures and multi-layers. We first discuss the technique, atomic layer-by-layer molecular beam epitaxy (ALL-MBE) engineering, that enabled High-Tc Interface Superconductivity (HT-IS), and the challenges associated with the realization of high quality interfaces. Then we turn our attention to the experiments which shed light on the structure and properties of interfacial layers, allowing comparison to those of single-phase films and bulk crystals. Both ‘passive’ hetero-structures as well as surface-induced effects by external gating are discussed. Here, we conclude by comparing HT-IS in cuprates and in other classes of materials, especially Fe-based superconductors, and by examining the grand challenges currently laying ahead for the field.

  1. Different approaches to generate matching effects using arrays in contact with superconducting films.

    NASA Astrophysics Data System (ADS)

    del Valle, J.; Gomez, A.; Luis-Hita, J.; Rollano, V.; Gonzalez, E. M.; Vicent, J. L.

    2017-02-01

    Superconducting films in contact with non-superconducting regular arrays can exhibit commensurability effects between the vortex lattice and the unit cell of the pinning array. These matching effects yield a slowdown of the vortex flow and the corresponding dissipation decrease. The superconducting samples are Nb films grown on Si substrates. We have studied these matching effects with the array on top, embedded or threading the Nb superconducting films and using different materials (Si, Cu, Ni, Py dots and dots fabricated with Co/Pd multilayers). These hybrids allow for studying the contribution of different pinning potentials to the matching effects. The main findings are: (i) Periodic roughness induced in the superconducting film is enough to generate resistivity minima; (ii) A minor effect is achieved by magnetic pinning from periodic magnetic field potentials obtained by dots with out of plane magnetization grown on top of the superconducting film, (iii) In the case of array of magnetic dots embedded in the films, vortex flow probes the magnetic state; i.e. magnetoresistance measurements detect the magnetic state of very small nanomagnets. In addition, we have studied the role played by the local order in the commensurability effects. This was attained using an array that mimics a smectic crystal. We have found that preserving the local order is crucial. If the local order is not retained the magnetoresistance minima vanish.

  2. Superconductive wire

    DOEpatents

    Korzekwa, David A.; Bingert, John F.; Peterson, Dean E.; Sheinberg, Haskell

    1995-01-01

    A superconductive article is made by inserting a rigid mandrel into an internal cavity of a first metallic tube, said tube having an interior surface and an exterior surface, said interior surface defining the interior cavity, forming a layer of a superconductive material or superconductive precursor upon the exterior surface of said first metallic tube, machining the layer of superconductive material or superconductive precursor to a predetermined diameter to form an intermediate article configured for insertion into a second metallic tube having an interior diameter corresponding to the predetermined diameter, inserting the machined intermediate article into a second metallic tube having an internal diameter corresponding to the predetermined diameter of the intermediate article to form a composite intermediate article, reducing or ironing the composite intermediate article to a predetermined cross-sectional diameter, and sintering the reduced or ironed composite intermediate article at temperatures and for time sufficient for the superconductive material or superconductive precursor to exhibit superconductivity.

  3. Superconductive wire

    DOEpatents

    Korzekwa, D.A.; Bingert, J.F.; Peterson, D.E.; Sheinberg, H.

    1995-07-18

    A superconductive article is made by inserting a rigid mandrel into an internal cavity of a first metallic tube, said tube having an interior surface and an exterior surface, said interior surface defining the interior cavity, forming a layer of a superconductive material or superconductive precursor upon the exterior surface of said first metallic tube, machining the layer of superconductive material or superconductive precursor to a predetermined diameter to form an intermediate article configured for insertion into a second metallic tube having an interior diameter corresponding to the predetermined diameter, inserting the machined intermediate article into a second metallic tube having an internal diameter corresponding to the predetermined diameter of the intermediate article to form a composite intermediate article, reducing or ironing the composite intermediate article to a predetermined cross-sectional diameter, and sintering the reduced or ironed composite intermediate article at temperatures and for time sufficient for the superconductive material or superconductive precursor to exhibit superconductivity. 2 figs.

  4. Superconducting transistor

    DOEpatents

    Gray, Kenneth E.

    1979-01-01

    A superconducting transistor is formed by disposing three thin films of superconducting material in a planar parallel arrangement and insulating the films from each other by layers of insulating oxides to form two tunnel junctions. One junction is biased above twice the superconducting energy gap and the other is biased at less than twice the superconducting energy gap. Injection of quasiparticles into the center film by one junction provides a current gain in the second junction.

  5. Architecture for high critical current superconducting tapes

    DOEpatents

    Jia, Quanxi; Foltyn, Stephen R.

    2002-01-01

    Improvements in critical current capacity for superconducting film structures are disclosed and include the use of, e.g., multilayer YBCO structures where individual YBCO layers are separated by a layer of an insulating material such as CeO.sub.2 and the like, a layer of a conducting material such as strontium ruthenium oxide and the like or by a second superconducting material such as SmBCO and the like.

  6. Laser beam induced nanoscale spot through nonlinear “thick” samples: A multi-layer thin lens self-focusing model

    SciTech Connect

    Wei, Jingsong; Yan, Hui

    2014-08-14

    Self-focusing is a well-researched phenomenon. Nanoscale spots can be achieved through self-focusing, which is an alternative method for achieving high-density data storage, high-resolution light imaging, and maskless nanolithography. Several research groups have observed that self-focusing spots can be reduced to nanoscale levels via incident laser power manipulation. Self-focusing spots can be analyzed by solving the nonlinear Schrödinger equation and the finite difference time domain method. However, both procedures are complex and time-consuming. In the present work, a multi-layer thin-lens self-focusing model that considers diffraction effects and changes of refractive index along the radial and film thickness directions is proposed to analyze the self-focusing behavior and traveling process of light beams intuitively. The self-focusing behaviors of As{sub 2}S{sub 3} are simulated, and results show that a nanoscale self-focusing spot with a radius of about 0.12 μm can be formed at the bottom of nonlinear sample when the incident laser power exceeds 4.25 mW. Our findings are basically consistent with experimental reports and provide a good method for analyzing and understanding the self-focusing process. An appropriate application schematic design is also provided.

  7. Multilayer high performance insulation materials

    NASA Technical Reports Server (NTRS)

    Stuckey, J. M.

    1971-01-01

    A number of tests are required to evaluate both multilayer high performance insulation samples and the materials that comprise them. Some of the techniques and tests being employed for these evaluations and some of the results obtained from thermal conductivity tests, outgassing studies, effect of pressure on layer density tests, hypervelocity impact tests, and a multilayer high performance insulation ambient storage program at the Kennedy Space Center are presented.

  8. Efficient Blind Spectral Unmixing of Fluorescently Labeled Samples Using Multi-Layer Non-Negative Matrix Factorization

    PubMed Central

    Zudaire, Isabel; Ortiz-de-Solorzano, Carlos

    2013-01-01

    The ample variety of labeling dyes and staining methods available in fluorescence microscopy has enabled biologists to advance in the understanding of living organisms at cellular and molecular level. When two or more fluorescent dyes are used in the same preparation, or one dye is used in the presence of autofluorescence, the separation of the fluorescent emissions can become problematic. Various approaches have been recently proposed to solve this problem. Among them, blind non-negative matrix factorization is gaining interest since it requires little assumptions about the spectra and concentration of the fluorochromes. In this paper, we propose a novel algorithm for blind spectral separation that addresses some of the shortcomings of existing solutions: namely, their dependency on the initialization and their slow convergence. We apply this new algorithm to two relevant problems in fluorescence microscopy: autofluorescence elimination and spectral unmixing of multi-labeled samples. Our results show that our new algorithm performs well when compared with the state-of-the-art approaches for a much faster implementation. PMID:24260120

  9. Superconducting NbTiN thin films for superconducting radio frequency accelerator cavity applications

    DOE PAGES

    Burton, Matthew C.; Beebe, Melissa R.; Yang, Kaida; ...

    2016-02-12

    Current superconducting radio frequency technology, used in various particle accelerator facilities across the world, is reliant upon bulk niobium superconducting cavities. Due to technological advancements in the processing of bulk Nb cavities, the facilities have reached accelerating fields very close to a material-dependent limit, which is close to 50 MV/m for bulk Nb. One possible solution to improve upon this fundamental limitation was proposed a few years ago by Gurevich [Appl. Phys. Lett. 88, 012511 (2006)], consisting of the deposition of alternating thin layers of superconducting and insulating materials on the interior surface of the cavities. The use of type-IImore » superconductors with Tc > TcNb and Hc > HcNb, (e.g., Nb3Sn, NbN, or NbTiN) could potentially greatly reduce the surface resistance (Rs) and enhance the accelerating field, if the onset of vortex penetration is increased above HcNb, thus enabling higher field gradients. Although Nb3Sn may prove superior, it is not clear that it can be grown as a suitable thin film for the proposed multilayer approach, since very high temperature is typically required for its growth, hindering achieving smooth interfaces and/or surfaces. On the other hand, since NbTiN has a smaller lower critical field (Hc1) and higher critical temperature (Tc) than Nb and increased conductivity compared to NbN, it is a promising candidate material for this new scheme. Here, the authors present experimental results correlating filmmicrostructure with superconducting properties on NbTiN thin film coupon samples while also comparing filmsgrown with targets of different stoichiometry. In conclusion, it is worth mentioning that the authors have achieved thin films with bulk-like lattice parameter and transition temperature while also achieving Hc1 values larger than bulk for films thinner than their London penetration depths.« less

  10. Superconducting Cable

    DOEpatents

    Hughey, Raburn L.; Sinha, Uday K.; Reece, David S.; Muller, Albert C.

    2005-07-22

    In order to provide a flexible oxide superconducting cable which is reduced in AC loss, tape-shaped superconducting wires covered with a stabilizing metal are wound on a flexible former. The superconducting wires are preferably laid on the former at a bending strain of not more than 0.2%. In laying on the former, a number of tape-shaped superconducting wires are laid on a core member in a side-by-side manner, to form a first layer. A prescribed number of tape-shaped superconducting wires are laid on top of the first layer in a side-by-side manner, to form a second layer. The former may be made of a metal, plastic, reinforced plastic, polymer, or a composite and provides flexibility to the superconducting wires and the cable formed therewith.

  11. Superconducting Cable

    DOEpatents

    Hughey, Raburn L.; Sinha, Uday K.; Reece, David S.; Muller, Albert C.

    2005-03-08

    In order to provide a flexible oxide superconducting cable which is reduced in AC loss, tape-shaped superconducting wires covered with a stabilizing metal are wound on a flexible former. The superconducting wires are preferably laid on the former at a bending strain of not more than 0.2%. In laying on the former, a number of tape-shaped superconducting wires are laid on a core member in a side-by-side manner, to form a first layer. A prescribed number of tape-shaped superconducting wires are laid on top of the first layer in a side-by-side manner, to form a second layer. The former may be made of a metal, plastic, reinforced plastic, polymer, or a composite and provides flexibility to the superconducting wires and the cable formed therewith.

  12. WAFER TEST CAVITY -Linking Surface Microstructure to RF Performance: a ‘Short-­Sample Test Facility’ for characterizing superconducting materials for SRF cavities.

    SciTech Connect

    Pogue, Nathaniel; Comeaux, Justin; McIntyre, Peter

    2014-05-30

    The Wafer Test cavity was designed to create a short sample test system to determine the properties of the superconducting materials and S-I-S hetero-structures. The project, funded by ARRA, was successful in accomplishing several goals to achieving a high gradient test system for SRF research and development. The project led to the design and construction of the two unique cavities that each severed unique purposes: the Wafer test Cavity and the Sapphire Test cavity. The Sapphire Cavity was constructed first to determine the properties of large single crystal sapphires in an SRF environment. The data obtained from the cavity greatly altered the design of the Wafer Cavity and provided the necessary information to ascertain the Wafer Test cavity’s performance.

  13. Superconducting Materials

    NASA Technical Reports Server (NTRS)

    1995-01-01

    After working with Lewis Research Center and Jet Propulsion Laboratory, Superconducting Technologies, Inc. (STI) adapted NASA requirements and refined its own standard production recipe. STI uses high temperature superconducting (HTS) materials in its basic products: high quality thin films, circuits and components. Applications include microwave circuits for radar to reduce interference.

  14. Superconducting structure

    DOEpatents

    Kwon, Chuhee; Jia, Quanxi; Foltyn, Stephen R.

    2003-04-01

    A superconductive structure including a dielectric oxide substrate, a thin buffer layer of a superconducting material thereon; and, a layer of a rare earth-barium-copper oxide superconducting film thereon the thin layer of yttrium-barium-copper oxide, the rare earth selected from the group consisting of samarium, gadolinium, ytterbium, erbium, neodymium, dysprosium, holmium, lutetium, a combination of more than one element from the rare earth group and a combination of one or more elements from the rare earth group with yttrium, the buffer layer of superconducting material characterized as having chemical and structural compatibility with the dielectric oxide substrate and the rare earth-barium-copper oxide superconducting film is provided.

  15. Superconducting Structure

    DOEpatents

    Kwon, Chuhee; Jia, Quanxi; Foltyn, Stephen R.

    2005-09-13

    A superconductive structure including a dielectric oxide substrate, a thin buffer layer of a superconducting material thereon; and, a layer of a rare earth-barium-copper oxide superconducting film thereon the thin layer of yttrium-barium-copper oxide, the rare earth selected from the group consisting of samarium, gadolinium, ytterbium, erbium, neodymium, dysprosium, holmium, lutetium, a combination of more than one element from the rare earth group and a combination of one or more elements from the rare earth group with yttrium, the buffer layer of superconducting material characterized as having chemical and structural compatibility with the dielectric oxide substrate and the rare earth-barium-copper oxide superconducting film is provided.

  16. Magnetic multilayer structure

    DOEpatents

    Herget, Philipp; O'Sullivan, Eugene J.; Romankiw, Lubomyr T.; Wang, Naigang; Webb, Bucknell C.

    2017-03-21

    A mechanism is provided for an integrated laminated magnetic device. A substrate and a multilayer stack structure form the device. The multilayer stack structure includes alternating magnetic layers and diode structures formed on the substrate. Each magnetic layer in the multilayer stack structure is separated from another magnetic layer in the multilayer stack structure by a diode structure.

  17. Magnetic multilayer structure

    SciTech Connect

    Herget, Philipp; O'Sullivan, Eugene J.; Romankiw, Lubomyr T.; Wang, Naigang; Webb, Bucknell C.

    2016-07-05

    A mechanism is provided for an integrated laminated magnetic device. A substrate and a multilayer stack structure form the device. The multilayer stack structure includes alternating magnetic layers and diode structures formed on the substrate. Each magnetic layer in the multilayer stack structure is separated from another magnetic layer in the multilayer stack structure by a diode structure.

  18. Fabrication and Characterization of Samples for a Material Migration Experiment on the Experimental Advanced Superconducting Tokamak (EAST).

    SciTech Connect

    Wampler, William R.; Van Deusen, Stuart B.

    2015-12-01

    This report documents work done for the ITER International Fusion Energy Organization (Sponsor) under a Funds-In Agreement FI 011140916 with Sandia National Laboratories. The work consists of preparing and analyzing samples for an experiment to measure material erosion and deposition in the EAST Tokamak. Sample preparation consisted of depositing thin films of carbon and aluminum onto molybdenum tiles. Analysis consists of measuring the thickness of films before and after exposure to helium plasma in EAST. From these measurements the net erosion and deposition of material will be quantified. Film thickness measurements are made at the Sandia Ion Beam Laboratory using Rutherford backscattering spectrometry and nuclear reaction analysis, as described in this report. This report describes the film deposition and pre-exposure analysis. Results from analysis after plasma exposure will be given in a subsequent report.

  19. Defects in GaAs bulk crystals and multi-layers caused by In diffusion

    SciTech Connect

    Werner, P.; Baranowski, J.

    1993-04-01

    The objective was to study by transmission electron microscopy the lattice defects in GaAs bulk crystals and heterostructures formed by In diffusion. In such samples hints for the existence of superconductivity have been found. Indium was found to move more than 100 {mu}m into bulk GaAs during lh annealing at 550C (such conditions are typical for molecular beam epitaxy growth on GaAs wafers). This rapid diffusion is accompanied by the creation of dislocation networks and metallic In droplets that show evidence for lattice strain. To study the interaction of In with the GaAs lattice, In/GaAs multi-layers were grown by MBE at about 450C on a GaAs buffer layer. The interfaces of these structures showed misfit dislocations at islands of InAs besides the presence of lattice strain. Both types of samples showed microwave absorption signals typical for superconductivity. The most likely superconductive phases are small metastable inclusions, probably consisting amorphous Ga or In.

  20. Superconducting Memristors

    NASA Astrophysics Data System (ADS)

    Peotta, Sebastiano; Di Ventra, Massimiliano

    2014-09-01

    In his original work, Josephson predicted that a phase-dependent conductance should be present in superconducting tunnel junctions, an effect difficult to detect, mainly because it is hard to single it out from the usual nondissipative Josephson current. We propose a solution for this problem that consists of using different superconducting materials to realize the two junctions of a superconducting interferometer. According to the Ambegaokar-Baratoff relation the two junctions have different conductances if the critical currents are equal, thus the Josephson current can be suppressed by fixing the magnetic flux in the loop at half of a flux quantum without canceling the phase-dependent conductance. Our proposal can be used to study the phase-dependent conductance, an effect present in principle in all superconducting weak links. From the standpoint of nonlinear circuit theory, such a device is in fact an ideal memristor with possible applications to memories and neuromorphic computing in the framework of ultrafast and low-energy-consumption superconducting digital circuits.

  1. Visualizing domain wall and reverse domain superconductivity.

    PubMed

    Iavarone, M; Moore, S A; Fedor, J; Ciocys, S T; Karapetrov, G; Pearson, J; Novosad, V; Bader, S D

    2014-08-28

    In magnetically coupled, planar ferromagnet-superconductor (F/S) hybrid structures, magnetic domain walls can be used to spatially confine the superconductivity. In contrast to a superconductor in a uniform applied magnetic field, the nucleation of the superconducting order parameter in F/S structures is governed by the inhomogeneous magnetic field distribution. The interplay between the superconductivity localized at the domain walls and far from the walls leads to effects such as re-entrant superconductivity and reverse domain superconductivity with the critical temperature depending upon the location. Here we use scanning tunnelling spectroscopy to directly image the nucleation of superconductivity at the domain wall in F/S structures realized with Co-Pd multilayers and Pb thin films. Our results demonstrate that such F/S structures are attractive model systems that offer the possibility to control the strength and the location of the superconducting nucleus by applying an external magnetic field, potentially useful to guide vortices for computing application.

  2. Demonstration of superconducting micromachined cavities

    SciTech Connect

    Brecht, T. Reagor, M.; Chu, Y.; Pfaff, W.; Wang, C.; Frunzio, L.; Devoret, M. H.; Schoelkopf, R. J.

    2015-11-09

    Superconducting enclosures will be key components of scalable quantum computing devices based on circuit quantum electrodynamics. Within a densely integrated device, they can protect qubits from noise and serve as quantum memory units. Whether constructed by machining bulk pieces of metal or microfabricating wafers, 3D enclosures are typically assembled from two or more parts. The resulting seams potentially dissipate crossing currents and limit performance. In this letter, we present measured quality factors of superconducting cavity resonators of several materials, dimensions, and seam locations. We observe that superconducting indium can be a low-loss RF conductor and form low-loss seams. Leveraging this, we create a superconducting micromachined resonator with indium that has a quality factor of two million, despite a greatly reduced mode volume. Inter-layer coupling to this type of resonator is achieved by an aperture located under a planar transmission line. The described techniques demonstrate a proof-of-principle for multilayer microwave integrated quantum circuits for scalable quantum computing.

  3. Superconducting magnets

    SciTech Connect

    Willen, E.; Dahl, P.; Herrera, J.

    1985-01-01

    This report provides a self-consistent description of a magnetic field in the aperture of a superconducting magnet and details how this field can be calculated in a magnet with cos theta current distribution in the coils. A description of an apparatus that can be used to measure the field uniformity in the aperture has been given. Finally, a detailed description of the magnet being developed for use in the Superconducting Super Collider is given. When this machine is built, it will be by far the largest application of superconductivity to date and promises to make possible the experimental discoveries needed to understand the basic laws of nature governing the world in which we live.

  4. Decoupling of the CuO2 plane and superconductivity in Cu0.5Tl0.5Ba2(Ca2-ySry)Cu3O10-δ(y = 0-0.4) samples

    NASA Astrophysics Data System (ADS)

    Khan, Nawazish A.; Usman Muzaffar, M.

    2016-05-01

    Cu0.5Tl0.5Ba2(Ca2-ySry)Cu3O10-δ(y = 0-0.4) samples have been synthesized at normal pressure at 860∘C. The main objectives of these experiments to study the role of inter-plane decoupling in suppressing the superconductivity of high temperature superconductors (HTSC). These samples have shown orthorhombic crystal structure and the c-axis length increases with increased Sr-doping. All the samples have shown metallic variations of resistivity (ρ) from room temperature down to the onset of superconductivity. The magnitude of the superconductivity is suppressed and the apical oxygen modes are hardened with Sr-doping. These studies have shown that Sr-doping promotes decoupling of conducting CuO2 planes which suppress the superconducting properties of final compound. The excess conductivity analyses have shown increases in the width of two-dimensional (2D) Lawrence-Doniach (LD) regime with Sr-doping. The coherence length along the c-axis ξc(0), the inter-layer coupling J, the phase relaxation time of the carriers τφ and the Fermi velocity vF of superconductor carriers is suppressed. The underlying reason for the suppression of superconductor properties is the decrease in the density of carriers in the superconductor planes. However, the values of Bc0(T), Bc1(T) and Jc(0) have been found to increase with the increased Sr-doping, which is suggested to be originating from the enhancement in the flux pinning character which is induced by Sr-doping. The values of magnetic field penetration depth λp.d and the Ginzburg-Landau (GL) parameter κ decrease with Sr-doping and it is also suggested to be originating from the increase of flux pinning character of the samples with Sr-doping.

  5. Physical properties of the superconducting spin-valve Fe/Cu/Fe/In heterostructure

    NASA Astrophysics Data System (ADS)

    Leksin, P. V.; Garif'yanov, N. N.; Garifullin, I. A.; Schumann, J.; Kataev, V.; Schmidt, O. G.; Büchner, B.

    2012-01-01

    We report on structural, magnetic, and superconducting properties of the spin-valve multilayer system CoOx/Fe1/Cu/Fe2/In. For most of the thicknesses of the second iron layer dFe2 up to 2 nm, we have observed a full spin-valve effect for the superconducting current, i.e., a complete transition from the normal to the superconducting state by changing the mutual orientation of the magnetizations of the Fe1 and Fe2 layers. For dFe2<1 nm, the superconducting transition temperature TcP for the parallel orientation of magnetizations of the Fe1 and Fe2 layers is smaller than that for the antiparallel orientation TcAP, which corresponds to the direct spin-valve effect. For dFe2⩾1 nm, we have found the inverse spin-valve effect with ΔTc=TcAP-TcP<0. Further, in samples with a fixed thickness of the In layer, we have observed an oscillating dependence of its superconducting transition temperature Tc on dFe2. The analysis of the Tc(dFe2) dependence using the theory of the superconducting-ferromagnetic proximity effect has enabled determination of all microscopic parameters of the studied system. With these parameters, a satisfactory description of the sign-changing oscillating behavior of the spin-valve effect ΔTc(dFe2) has been obtained using a recent theory by Fominov [Ya. V. Fominov , Pis'ma Zh. Eksp. Teor. Fiz. 91, 329 (2010) [JETP Lett.JTPLA20021-364010.1134/S002136401006010X 91, 308 (2010)

  6. PREFACE: Superconducting materials Superconducting materials

    NASA Astrophysics Data System (ADS)

    Charfi Kaddour, Samia; Singleton, John; Haddad, Sonia

    2011-11-01

    The discovery of superconductivity in 1911 was a great milestone in condensed matter physics. This discovery has resulted in an enormous amount of research activity. Collaboration among chemists and physicists, as well as experimentalists and theoreticians has given rise to very rich physics with significant potential applications ranging from electric power transmission to quantum information. Several superconducting materials have been synthesized. Crucial progress was made in 1987 with the discovery of high temperature superconductivity in copper-based compounds (cuprates) which have revealed new fascinating properties. Innovative theoretical tools have been developed to understand the striking features of cuprates which have remained for three decades the 'blue-eyed boy' for researchers in superconductor physics. The history of superconducting materials has been notably marked by the discovery of other compounds, particularly organic superconductors which despite their low critical temperature continue to attract great interest regarding their exotic properties. Last but not least, the recent observation of superconductivity in iron-based materials (pnictides) has renewed hope in reaching room temperature superconductivity. However, despite intense worldwide studies, several features related to this phenomenon remain unveiled. One of the fundamental key questions is the mechanism by which superconductivity takes place. Superconductors continue to hide their 'secret garden'. The new trends in the physics of superconductivity have been one of the two basic topics of the International Conference on Conducting Materials (ICoCoM2010) held in Sousse,Tunisia on 3-7 November 2010 and organized by the Tunisian Physical Society. The conference was a nice opportunity to bring together participants from multidisciplinary domains in the physics of superconductivity. This special section contains papers submitted by participants who gave an oral contribution at ICoCoM2010

  7. Superconducting Microelectronics.

    ERIC Educational Resources Information Center

    Henry, Richard W.

    1984-01-01

    Discusses superconducting microelectronics based on the Josephson effect and its advantages over conventional integrated circuits in speed and sensitivity. Considers present uses in standards laboratories (voltage) and in measuring weak magnetic fields. Also considers future applications in superfast computer circuitry using Superconducting…

  8. On the superconductivity of graphite interfaces

    NASA Astrophysics Data System (ADS)

    Esquinazi, P.; Heikkilä, T. T.; Lysogorskiy, Y. V.; Tayurskii, D. A.; Volovik, G. E.

    2014-11-01

    We propose an explanation for the appearance of superconductivity at the interfaces of graphite with Bernal stacking order. A network of line defects with flat bands appears at the interfaces between two slightly twisted graphite structures. Due to the flat band the probability to find high temperature superconductivity at these quasi one-dimensional corridors is strongly enhanced. When the network of superconducting lines is dense it becomes effectively two-dimensional. The model provides an explanation for several reports on the observation of superconductivity up to room temperature in different oriented graphite samples, graphite powders as well as graphite-composite samples published in the past.

  9. Hybrid superconducting neutron detectors

    SciTech Connect

    Merlo, V.; Lucci, M.; Ottaviani, I.; Salvato, M.; Cirillo, M.; Scherillo, A.; Celentano, G.; Pietropaolo, A.

    2015-03-16

    A neutron detection concept is presented that is based on superconductive niobium (Nb) strips coated by a boron (B) layer. The working principle of the detector relies on the nuclear reaction, {sup 10}B + n → α + {sup 7}Li, with α and Li ions generating a hot spot on the current-biased Nb strip which in turn induces a superconducting-normal state transition. The latter is recognized as a voltage signal which is the evidence of the incident neutron. The above described detection principle has been experimentally assessed and verified by irradiating the samples with a pulsed neutron beam at the ISIS spallation neutron source (UK). It is found that the boron coated superconducting strips, kept at a temperature T = 8 K and current-biased below the critical current I{sub c}, are driven into the normal state upon thermal neutron irradiation. As a result of the transition, voltage pulses in excess of 40 mV are measured while the bias current can be properly modulated to bring the strip back to the superconducting state, thus resetting the detector. Measurements on the counting rate of the device are presented and the basic physical features of the detector are discussed.

  10. Hybrid superconducting neutron detectors

    NASA Astrophysics Data System (ADS)

    Merlo, V.; Salvato, M.; Cirillo, M.; Lucci, M.; Ottaviani, I.; Scherillo, A.; Celentano, G.; Pietropaolo, A.

    2015-03-01

    A neutron detection concept is presented that is based on superconductive niobium (Nb) strips coated by a boron (B) layer. The working principle of the detector relies on the nuclear reaction, 10B + n → α + 7Li, with α and Li ions generating a hot spot on the current-biased Nb strip which in turn induces a superconducting-normal state transition. The latter is recognized as a voltage signal which is the evidence of the incident neutron. The above described detection principle has been experimentally assessed and verified by irradiating the samples with a pulsed neutron beam at the ISIS spallation neutron source (UK). It is found that the boron coated superconducting strips, kept at a temperature T = 8 K and current-biased below the critical current Ic, are driven into the normal state upon thermal neutron irradiation. As a result of the transition, voltage pulses in excess of 40 mV are measured while the bias current can be properly modulated to bring the strip back to the superconducting state, thus resetting the detector. Measurements on the counting rate of the device are presented and the basic physical features of the detector are discussed.

  11. Superconducting thermal neutron detectors

    NASA Astrophysics Data System (ADS)

    Merlo, V.; Pietropaolo, A.; Celentano, G.; Cirillo, M.; Lucci, M.; Ottaviani, I.; Salvato, M.; Scherillo, A.; Schooneveld, E. M.; Vannozzi, A.

    2016-09-01

    A neutron detection concept is presented that is based on superconductive niobium nitride (NbN) strips coated by a boron (B) layer. The working principle is well described by a hot spot mechanism: upon the occurrence of the nuclear reactions n + 10B → α + 7Li + 2.8 MeV, the energy released by the secondary particles into the strip induces a superconducting-normal state transition. The latter is recognized as a voltage signal which is the evidence of the incident neutron. The above described detection principle has been experimentally assessed and verified by irradiating the samples with a pulsed neutron beam at the ISIS spallation neutron source (UK). It is found that the boron coated superconducting strips, kept at a temperature T below 11K and current-biased below the critical current IC, are driven into the normal state upon thermal neutron irradiation. Measurements on the counting rate of the device are presented and the basic physical features of the detector are discussed and compared to those of a borated Nb superconducting strip.

  12. A Simple Demonstration of High Tc Superconductive Powder.

    ERIC Educational Resources Information Center

    Baker, Roger; Thompson, James C.

    1987-01-01

    Described is a simple demonstration that provides a way to determine if a given sample contains even a small fraction of superconducting material. The repulsion of the powder from a magnetic field is indicative of superconductivity. (RH)

  13. Superconducting NbTiN thin films for superconducting radio frequency accelerator cavity applications

    SciTech Connect

    Burton, Matthew C.; Beebe, Melissa R.; Yang, Kaida; Lukaszew, Rosa A.; Valente-Feliciano, Anne -Marie; Reece, Charles

    2016-02-12

    Current superconducting radio frequency technology, used in various particle accelerator facilities across the world, is reliant upon bulk niobium superconducting cavities. Due to technological advancements in the processing of bulk Nb cavities, the facilities have reached accelerating fields very close to a material-dependent limit, which is close to 50 MV/m for bulk Nb. One possible solution to improve upon this fundamental limitation was proposed a few years ago by Gurevich [Appl. Phys. Lett. 88, 012511 (2006)], consisting of the deposition of alternating thin layers of superconducting and insulating materials on the interior surface of the cavities. The use of type-II superconductors with Tc > TcNb and Hc > HcNb, (e.g., Nb3Sn, NbN, or NbTiN) could potentially greatly reduce the surface resistance (Rs) and enhance the accelerating field, if the onset of vortex penetration is increased above HcNb, thus enabling higher field gradients. Although Nb3Sn may prove superior, it is not clear that it can be grown as a suitable thin film for the proposed multilayer approach, since very high temperature is typically required for its growth, hindering achieving smooth interfaces and/or surfaces. On the other hand, since NbTiN has a smaller lower critical field (Hc1) and higher critical temperature (Tc) than Nb and increased conductivity compared to NbN, it is a promising candidate material for this new scheme. Here, the authors present experimental results correlating filmmicrostructure with superconducting properties on NbTiN thin film coupon samples while also comparing filmsgrown with targets of different stoichiometry. In conclusion, it is worth mentioning that the authors have achieved thin films with bulk-like lattice parameter and transition temperature while also achieving Hc1 values larger than bulk for films thinner than their London penetration depths.

  14. Search for Superconductivity in Micrometeorites

    NASA Astrophysics Data System (ADS)

    Guénon, S.; Ramírez, J. G.; Basaran, Ali C.; Wampler, J.; Thiemens, M.; Taylor, S.; Schuller, Ivan K.

    2014-12-01

    We have developed a very sensitive, highly selective, non-destructive technique for screening inhomogeneous materials for the presence of superconductivity. This technique, based on phase sensitive detection of microwave absorption is capable of detecting 10-12 cc of a superconductor embedded in a non-superconducting, non-magnetic matrix. For the first time, we apply this technique to the search for superconductivity in extraterrestrial samples. We tested approximately 65 micrometeorites collected from the water well at the Amundsen-Scott South pole station and compared their spectra with those of eight reference materials. None of these micrometeorites contained superconducting compounds, but we saw the Verwey transition of magnetite in our microwave system. This demonstrates that we are able to detect electro-magnetic phase transitions in extraterrestrial materials at cryogenic temperatures.

  15. Search for Superconductivity in Micrometeorites

    PubMed Central

    Guénon, S.; Ramírez, J. G.; Basaran, Ali C.; Wampler, J.; Thiemens, M.; Taylor, S.; Schuller, Ivan K.

    2014-01-01

    We have developed a very sensitive, highly selective, non-destructive technique for screening inhomogeneous materials for the presence of superconductivity. This technique, based on phase sensitive detection of microwave absorption is capable of detecting 10−12 cc of a superconductor embedded in a non-superconducting, non-magnetic matrix. For the first time, we apply this technique to the search for superconductivity in extraterrestrial samples. We tested approximately 65 micrometeorites collected from the water well at the Amundsen-Scott South pole station and compared their spectra with those of eight reference materials. None of these micrometeorites contained superconducting compounds, but we saw the Verwey transition of magnetite in our microwave system. This demonstrates that we are able to detect electro-magnetic phase transitions in extraterrestrial materials at cryogenic temperatures. PMID:25476841

  16. Search for superconductivity in micrometeorites.

    PubMed

    Guénon, S; Ramírez, J G; Basaran, Ali C; Wampler, J; Thiemens, M; Taylor, S; Schuller, Ivan K

    2014-12-05

    We have developed a very sensitive, highly selective, non-destructive technique for screening inhomogeneous materials for the presence of superconductivity. This technique, based on phase sensitive detection of microwave absorption is capable of detecting 10(-12) cc of a superconductor embedded in a non-superconducting, non-magnetic matrix. For the first time, we apply this technique to the search for superconductivity in extraterrestrial samples. We tested approximately 65 micrometeorites collected from the water well at the Amundsen-Scott South pole station and compared their spectra with those of eight reference materials. None of these micrometeorites contained superconducting compounds, but we saw the Verwey transition of magnetite in our microwave system. This demonstrates that we are able to detect electro-magnetic phase transitions in extraterrestrial materials at cryogenic temperatures.

  17. SUPERCONDUCTING PHOTOINJECTOR

    SciTech Connect

    BEN-ZVI,I.; BURRILL, A.; CALAGA, R.; CHANG, X.; GROVER, R.; GUPTA, R.; HAHN, H.; HAMMONS, L.; KAYRAN, D.; KEWISCH, J.; LAMBIASE, R.; LITVINENKO, V.; MCINTYRE, G.; NAIK, D.; PATE, D.; PHILLIPS, D.; POZDEYEV, E.; RAO, T.; SMEDLEY, J.; THAN, R.; TODD, R.; WEISS, D.; WU, Q.; ZALTSMAN, A.; ET AL.

    2007-08-26

    One of the frontiers in FEL science is that of high power. In order to reach power in the megawatt range, one requires a current of the order of one ampere with a reasonably good emittance. The superconducting laser-photocathode RF gun with a high quantum efficiency photocathode is the most natural candidate to provide this performance. The development of a 1/2 cell superconducting photoinjector designed to operate at up to a current of 0.5 amperes and beam energy of 2 MeV and its photocathode system are the subjects covered in this paper. The main issues are the photocathode and its insertion mechanism, the power coupling and High Order Mode damping. This technology is being developed at BNL for DOE nuclear physics applications such as electron cooling at high energy and electron ion colliders..

  18. Color superconductivity

    SciTech Connect

    Wilczek, F.

    1997-09-22

    The asymptotic freedom of QCD suggests that at high density - where one forms a Fermi surface at very high momenta - weak coupling methods apply. These methods suggest that chiral symmetry is restored and that an instability toward color triplet condensation (color superconductivity) sets in. Here I attempt, using variational methods, to estimate these effects more precisely. Highlights include demonstration of a negative pressure in the uniform density chiral broken phase for any non-zero condensation, which we take as evidence for the philosophy of the MIT bag model; and demonstration that the color gap is substantial - several tens of MeV - even at modest densities. Since the superconductivity is in a pseudoscalar channel, parity is spontaneously broken.

  19. Superconducting magnet

    NASA Technical Reports Server (NTRS)

    1985-01-01

    Extensive computer based engineering design effort resulted in optimization of a superconducting magnet design with an average bulk current density of approximately 12KA/cm(2). Twisted, stranded 0.0045 inch diameter NbTi superconductor in a copper matrix was selected. Winding the coil from this bundle facilitated uniform winding of the small diameter wire. Test coils were wound using a first lot of the wire. The actual packing density was measured from these. Interwinding voltage break down tests on the test coils indicated the need for adjustment of the wire insulation on the lot of wire subsequently ordered for construction of the delivered superconducting magnet. Using the actual packing densities from the test coils, a final magnet design, with the required enhancement and field profile, was generated. All mechanical and thermal design parameters were then also fixed. The superconducting magnet was then fabricated and tested. The first test was made with the magnet immersed in liquid helium at 4.2K. The second test was conducted at 2K in vacuum. In the latter test, the magnet was conduction cooled from the mounting flange end.

  20. Multilayer Insulation Material Guidelines

    NASA Technical Reports Server (NTRS)

    Finckenor, M. M.; Dooling, D.

    1999-01-01

    Multilayer Insulation Material Guidelines provides data on multilayer insulation materials used by previous spacecraft such as Spacelab and the Long-Duration Exposure Facility and outlines other concerns. The data presented in the document are presented for information only. They can be used as guidelines for multilayer insulation design for future spacecraft provided the thermal requirements of each new design and the environmental effects on these materials are taken into account.

  1. Stripes and superconductivity in cuprate superconductors

    NASA Astrophysics Data System (ADS)

    Tranquada, J. M.

    2005-08-01

    One type of order that has been observed to compete with superconductivity in cuprates involves alternating charge and antiferromagnetic stripes. Recent neutron scattering studies indicate that the magnetic excitation spectrum of a stripe-ordered sample is very similar to that observed in superconducting samples. In fact, it now appears that there may be a universal magnetic spectrum for the cuprates. One likely implication of this universal spectrum is that stripes of a dynamic form are present in the superconducting samples. On cooling through the superconducting transition temperature, a gap opens in the magnetic spectrum, and the weight lost at low energy piles up above the gap; the transition temperature is correlated with the size of the spin gap. Depending on the magnitude of the spin gap with respect to the magnetic spectrum, the enhanced magnetic scattering at low temperature can be either commensurate or incommensurate. Connections between stripe correlations and superconductivity are discussed.

  2. STRIPES AND SUPERCONDUCTIVITY IN CUPRATE SUPERCONDUCTORS

    SciTech Connect

    TRANQUADA, J.M.

    2005-08-22

    One type of order that has been observed to compete with superconductivity in cuprates involves alternating charge and antiferromagnetic stripes. Recent neutron scattering studies indicate that the magnetic excitation spectrum of a stripe-ordered sample is very similar to that observed in superconducting samples. In fact, it now appears that there may be a universal magnetic spectrum for the cuprates. One likely implication of this universal spectrum is that stripes of a dynamic form are present in the superconducting samples. On cooling through the superconducting transition temperature, a gap opens in the magnetic spectrum, and the weight lost at low energy piles up above the gap; the transition temperature is correlated with the size of the spin gap. Depending on the magnitude of the spin gap with respect to the magnetic spectrum, the enhanced magnetic scattering at low temperature can be either commensurate or incommensurate. Connections between stripe correlations and superconductivity are discussed.

  3. High temperature superconducting compounds

    NASA Astrophysics Data System (ADS)

    Goldman, Allen M.

    1992-11-01

    The major accomplishment of this grant has been to develop techniques for the in situ preparation of high-Tc superconducting films involving the use of ozone-assisted molecular beam epitaxy. The techniques are generalizable to the growth of trilayer and multilayer structures. Films of both the DyBa2Cu3O(7-x) and YBa2Cu3O(7-x) compounds as well as the La(2-x)Sr(x)CuO4 compound have been grown on the usual substrates, SrTiO3, YSZ, MgO, and LaAlO3, as well as on Si substrates without any buffer layer. A bolometer has been fabricated on a thermally isolated SiN substrate coated with YSZ, an effort carried out in collaboration with Honeywell Inc. The deposition process facilitates the fabrication of very thin and transparent films creating new opportunities for the study of superconductor-insulator transitions and the investigation of photo-doping with carriers of high temperature superconductors. In addition to a thin film technology, a patterning technology has been developed. Trilayer structures have been developed for FET devices and tunneling junctions. Other work includes the measurement of the magnetic properties of bulk single crystal high temperature superconductors, and in collaboration with Argonne National Laboratory, measurement of electric transport properties of T1-based high-Tc films.

  4. Superconducting Cable Termination

    DOEpatents

    Sinha, Uday K.; Tolbert, Jerry

    2005-08-30

    Disclosed is a termination that connects high temperature superconducting (HTS) cable immersed in pressurized liquid nitrogen to high voltage and neutral (shield) external bushings at ambient temperature and pressure. The termination consists of a splice between the HTS power (inner) and shield (outer) conductors and concentric copper pipes which are the conductors in the termination. There is also a transition from the dielectric tape insulator used in the HTS cable to the insulators used between and around the copper pipe conductors in the termination. At the warm end of the termination the copper pipes are connected via copper braided straps to the conventional warm external bushings which have low thermal stresses. This termination allows for a natural temperature gradient in the copper pipe conductors inside the termination which enables the controlled flashing of the pressurized liquid coolant (nitrogen) to the gaseous state. Thus the entire termination is near the coolant supply pressure and the high voltage and shield cold bushings, a highly stressed component used in most HTS cables, are eliminated. A sliding seal allows for cable contraction as it is cooled from room temperature to ˜72-82 K. Seals, static vacuum, and multi-layer superinsulation minimize radial heat leak to the environment.

  5. Dynamic effects of magnetic multilayer interlayer coupling

    SciTech Connect

    Pechan, M.J.; Xu, J. . Dept. of Physics); Kelly, D.M.; Schuller, I.K. . Dept. of Physics)

    1993-11-01

    Coupling between magnetic layers in multilayer samples gives rise to dynamic effects which are manifest as anomalous modes in ferromagnetic resonance (FMR) spectra. According to the model presented, antiferromagnetic (ferromagnetic) coupling would produce such modes on the high (low) field side of the uniform FMR mode. Anomalous modes, observed in Fe/Cu and Fe/Cr multilayer samples, are analyzed to obtain coupling constants as a function of nonmagnetic layer thickness. The modes are shown to arise from 180 out-of-phase interlayer magnetization precession. The coupling is observed to be antiferromagnetic in all samples and to be an order of magnitude greater in the Cr system than in the Cu.

  6. Modular, Multilayer Perceptron

    NASA Technical Reports Server (NTRS)

    Cheng, Li-Jen; Liu, Tsuen-Hsi

    1991-01-01

    Combination of proposed modular, multilayer perceptron and algorithm for its operation recognizes new objects after relatively brief retraining sessions. (Perceptron is multilayer, feedforward artificial neural network fully connected and trained via back-propagation learning algorithm.) Knowledge pertaining to each object to be recognized resides in subnetwork of full network, therefore not necessary to retrain full network to recognize each new object.

  7. Coexistence of ferromagnetism and superconductivity in YBCO nanoparticles.

    PubMed

    Zhu, Zhonghua; Gao, Daqiang; Dong, Chunhui; Yang, Guijin; Zhang, Jing; Zhang, Jinlin; Shi, Zhenhua; Gao, Hua; Luo, Honggang; Xue, Desheng

    2012-03-21

    Nanoparticles of superconducting YBa(2)Cu(3)O(7-δ) were synthesized via a citrate pyrolysis technique. Room temperature ferromagnetism was revealed in the samples by a vibrating sample magnetometer. Electron spin resonance spectra at selected temperatures indicated that there is a transition from the normal to the superconducting state at temperatures below 100 K. The M-T curves with various applied magnetic fields showed that the superconducting transition temperatures are 92 K and 55 K for the air-annealed and the post-annealed samples, respectively. Compared to the air-annealed sample, the saturation magnetization of the sample by reheating the air-annealed one in argon atmosphere is enhanced but its superconductivity is weakened, which implies that the ferromagnetism maybe originates from the surface oxygen defects. By superconducting quantum interference device measurements, we further confirmed the ferromagnetic behavior at high temperatures and interesting upturns in field cooling magnetization curves within the superconducting region are found. We attributed the upturn phenomena to the coexistence of ferromagnetism and superconductivity at low temperatures. Room temperature ferromagnetism of superconducting YBa(2)Cu(3)O(7-δ) nanoparticles has been observed in some previous related studies, but the issue of the coexistence of ferromagnetism and superconductivity within the superconducting region is still unclear. In the present work, it will be addressed in detail. The cooperation phenomena found in the spin-singlet superconductors will help us to understand the nature of superconductivity and ferromagnetism in more depth.

  8. Dephasing of conduction electrons by magnetic impurities in Cu/Ni and Cu/Cr samples: Influence of spin-glass transition on the superconducting proximity effect

    NASA Astrophysics Data System (ADS)

    Sosnin, I.; Nugent, P.; Zou, J.; Petrashov, V. T.; Volkov, A. F.

    2006-07-01

    The dependence of the superconducting proximity effect on the amount of magnetic impurities in the normal part of Andreev interferometers has been studied experimentally. The dephasing rates obtained from fitting experimental data to quasiclassical theory of the proximity effect are consistent with the spin flip scattering from Cr impurities forming a local moment in the Cu host. In contrast, Ni impurities do not form a local moment in Cu and as a result there is no extra dephasing from Ni as long as Cu/Ni alloy remain paramagnetic.

  9. Space applications of superconductivity

    NASA Technical Reports Server (NTRS)

    Sullivan, D. B.; Vorreiter, J. W.

    1979-01-01

    Some potential applications of superconductivity in space are summarized, e.g., the use of high field magnets for cosmic ray analysis or energy storage and generation, space applications of digital superconducting devices, such as the Josephson switch and, in the future, a superconducting computer. Other superconducting instrumentation which could be used in space includes: low frequency superconducting sensors, microwave and infrared detectors, instruments for gravitational studies, and high-Q cavities for use as stabilizing elements in clocks and oscillators.

  10. Multilayer dielectric diffraction gratings

    DOEpatents

    Perry, Michael D.; Britten, Jerald A.; Nguyen, Hoang T.; Boyd, Robert; Shore, Bruce W.

    1999-01-01

    The design and fabrication of dielectric grating structures with high diffraction efficiency used in reflection or transmission is described. By forming a multilayer structure of alternating index dielectric materials and placing a grating structure on top of the multilayer, a diffraction grating of adjustable efficiency, and variable optical bandwidth can be obtained. Diffraction efficiency into the first order in reflection varying between 1 and 98 percent has been achieved by controlling the design of the multilayer and the depth, shape, and material comprising the grooves of the grating structure. Methods for fabricating these gratings without the use of ion etching techniques are described.

  11. Multilayer dielectric diffraction gratings

    DOEpatents

    Perry, M.D.; Britten, J.A.; Nguyen, H.T.; Boyd, R.; Shore, B.W.

    1999-05-25

    The design and fabrication of dielectric grating structures with high diffraction efficiency used in reflection or transmission is described. By forming a multilayer structure of alternating index dielectric materials and placing a grating structure on top of the multilayer, a diffraction grating of adjustable efficiency, and variable optical bandwidth can be obtained. Diffraction efficiency into the first order in reflection varying between 1 and 98 percent has been achieved by controlling the design of the multilayer and the depth, shape, and material comprising the grooves of the grating structure. Methods for fabricating these gratings without the use of ion etching techniques are described. 7 figs.

  12. Coexistence of superconductivity and ferromagnetism in the d-band metal ZrZn2.

    PubMed

    Pfleiderer, C; Uhlarz, M; Hayden, S M; Vollmer, R; v Löhneysen, H; Bernhoeft, N R; Lonzarich, G G

    2001-07-05

    It has generally been believed that, within the context of the Bardeen-Cooper-Schrieffer (BCS) theory of superconductivity, the conduction electrons in a metal cannot be both ferromagnetically ordered and superconducting. Even when the superconductivity has been interpreted as arising from magnetic mediation of the paired electrons, it was thought that the superconducting state occurs in the paramagnetic phase. Here we report the observation of superconductivity in the ferromagnetically ordered phase of the d-electron compound ZrZn2. The specific heat anomaly associated with the superconducting transition in this material appears to be absent, and the superconducting state is very sensitive to defects, occurring only in very pure samples. Under hydrostatic pressure superconductivity and ferromagnetism disappear at the same pressure, so the ferromagnetic state appears to be a prerequisite for superconductivity. When combined with the recent observation of superconductivity in UGe2 (ref. 4), our results suggest that metallic ferromagnets may universally become superconducting when the magnetization is small.

  13. Generalized parafermions and nonlocal Josephson effect in multilayer systems

    NASA Astrophysics Data System (ADS)

    Ebisu, Hiromi; Sagi, Eran; Tanaka, Yukio; Oreg, Yuval

    2017-02-01

    We theoretically investigate the effects of backscattering and superconducting proximity terms between the edges of two multilayer fractional quantum Hall (FQH) systems. While the different layers are strongly interacting, we assume that tunneling between them is absent. Studying the boundaries between regions gapped by the two mechanisms in an N -layer system, we find N localized zero-mode operators, realizing a generalized parafermionic algebra. We further propose an experiment capable of probing imprints of the generalized parafermionic bound states. This is done by coupling different superconducting contacts to different layers and examining the periodicity of the Josephson effect as a function of the various relative superconducting phases. Remarkably, even if we apply a phase difference between the superconductors in one layer, we induce a Josephson current at the other layers due to interlayer interactions. Furthermore, while the Josephson effect is commonly used to probe only charged degrees of freedom, the possibility of independently controlling the superconducting phase differences between the layers allows us to find imprints of the neutral modes of the underlying multilayer system. In particular, we propose two configurations, one of which is capable of isolating the signal associated with the charge modes while the other probes the neutral modes.

  14. High field superconducting magnets

    NASA Technical Reports Server (NTRS)

    Hait, Thomas P. (Inventor); Shirron, Peter J. (Inventor)

    2011-01-01

    A superconducting magnet includes an insulating layer disposed about the surface of a mandrel; a superconducting wire wound in adjacent turns about the mandrel to form the superconducting magnet, wherein the superconducting wire is in thermal communication with the mandrel, and the superconducting magnet has a field-to-current ratio equal to or greater than 1.1 Tesla per Ampere; a thermally conductive potting material configured to fill interstices between the adjacent turns, wherein the thermally conductive potting material and the superconducting wire provide a path for dissipation of heat; and a voltage limiting device disposed across each end of the superconducting wire, wherein the voltage limiting device is configured to prevent a voltage excursion across the superconducting wire during quench of the superconducting magnet.

  15. Wedged multilayer Laue Lens.

    SciTech Connect

    Conley, R.; Liu, C.; Qian, J.; Kewish, C. M.; Macrander, A. T.; Yan, H.; Kang, H. C.; Maser, J.; Stephenson, G. B.

    2008-05-01

    A multilayer Laue lens (MLL) is an x-ray focusing optic fabricated from a multilayer structure consisting of thousands of layers of two different materials produced by thin-film deposition. The sequence of layer thicknesses is controlled to satisfy the Fresnel zone plate law and the multilayer is sectioned to form the optic. An improved MLL geometry can be created by growing each layer with an in-plane thickness gradient to form a wedge, so that every interface makes the correct angle with the incident beam for symmetric Bragg diffraction. The ultimate hard x-ray focusing performance of a wedged MLL has been predicted to be significantly better than that of a nonwedged MLL, giving subnanometer resolution with high efficiency. Here, we describe a method to deposit the multilayer structure needed for an ideal wedged MLL and report our initial deposition results to produce these structures.

  16. Femtosecond damage threshold of multilayer metal films

    NASA Astrophysics Data System (ADS)

    Ibrahim, Wael M. G.; Elsayed-Ali, Hani E.; Shinn, Michelle D.; Bonner, Carl E.

    2003-05-01

    With the availability of terawatt laser systems with subpicosecond pulses, laser damage to optical components has become the limiting factor for further increases in the output peak power. Evaluation of different material structures in accordance to their suitability for high-power laser systems is essential. Multi-shot damage experiments, using 110 fs laser pulses at 800 nm, on polycrystalline single layer gold films and multi-layer (gold-vanadium, and gold-titanium) films were conducted. The laser incident fluence was varied, in both cases, from 0.1 to 0.6 J/cm2. No evidence of surface damage was apparent in the gold sample up to a fluence of 0.3 J/cm2. The multilayer sample experienced the onset of surface damage at the lowest fluence value used of 0.1 J/cm2. Damage results are in contrast with the time resolved ultrafast thermoreflectivity measurements that revealed a reduction of the thermoreflectivity signal for the multilayer films. This decrease in the thermoreflectivity signal signifies a reduction in the surface electron temperature that should translate in a lower lattice temperature at the later stage. Hence, one should expect a higher damage threshold for the multilayer samples. Comparison of the experimental results with the predictions of the Two-Temperature Model (TTM) is presented. The damage threshold of the single layer gold film corresponds to the melting threshold predicted by the model. In contrast to the single layer gold film, the multi-layer sample damaged at almost one third the damage threshold predicted by the TTM model. Possible damage mechanisms leading to the early onset of damage for the multilayer films are discussed.

  17. Construction of phospholipid anti-biofouling multilayer on biomedical PET surfaces

    NASA Astrophysics Data System (ADS)

    Xu, Jian-Ping; Wang, Xiao-Li; Fan, De-Zeng; Ji, Jian; Shen, Jia-Cong

    2008-11-01

    The biomimetic phospholipid anti-biofouling multilayers were constructed on the biomedical poly(ethylene terephthalate) (PET) through the combination of layer-by-layer assembly and Michael addition reaction. Two biomacromolecules with opposite charges, alginate and chitosan, were sequentially adsorbed onto PET samples. The assembled multilayer was subsequently crosslinked with glutaraldehyde and biomimetic phospholipids was introduced into the assembled multilayer through the Michael addition of 2-methacryloyloxyethyl phosphorylcholine (MPC). The multilayer and phospholipid-modified PETs showed excellent hemocompatibility.

  18. Observation of Double-Dome Superconductivity in Potassium-Doped FeSe Thin Films.

    PubMed

    Song, Can-Li; Zhang, Hui-Min; Zhong, Yong; Hu, Xiao-Peng; Ji, Shuai-Hua; Wang, Lili; He, Ke; Ma, Xu-Cun; Xue, Qi-Kun

    2016-04-15

    We report on the emergence of two disconnected superconducting domes in alkali-metal potassium- (K-)doped FeSe ultrathin films grown on graphitized SiC(0001). The superconductivity exhibits hypersensitivity to K dosage in the lower-T_{c} dome, whereas in the heavily electron-doped higher-T_{c} dome it becomes spatially homogeneous and robust against disorder, supportive of a conventional Cooper-pairing mechanism. Furthermore, the heavily K-doped multilayer FeSe films all reveal a large superconducting gap of ∼14  meV, irrespective of film thickness, verifying the higher-T_{c} superconductivity only in the topmost FeSe layer. The unusual finding of a double-dome superconducting phase is a step towards the mechanistic understanding of superconductivity in FeSe-derived superconductors.

  19. Superconducting magnet

    DOEpatents

    Satti, John A.

    1980-01-01

    A superconducting magnet designed to produce magnetic flux densities of the order of 4 to 5 Webers per square meter is constructed by first forming a cable of a plurality of matrixed superconductor wires with each wire of the plurality insulated from each other one. The cable is shaped into a rectangular cross-section and is wound with tape in an open spiral to create cooling channels. Coils are wound in a calculated pattern in saddle shapes to produce desired fields, such as dipoles, quadrupoles, and the like. Wedges are inserted between adjacent cables as needed to maintain substantially radial placement of the long dimensions of cross sections of the cables. After winding, individual strands in each of the cables are brought out to terminals and are interconnected to place all of the strands in series and to maximize the propagation of a quench by alternating conduction from an inner layer to an outer layer and from top half to bottom half as often as possible. Individual layers are separated from others by spiraled aluminum spacers to facilitate cooling. The wound coil is wrapped with an epoxy tape that is cured by heat and then machined to an interference fit with an outer aluminum pipe which is then affixed securely to the assembled coil by heating it to make a shrink fit. In an alternate embodiment, one wire of the cable is made of copper or the like to be heated externally to propagate a quench.

  20. Reliability of large superconducting magnets through design

    NASA Astrophysics Data System (ADS)

    Henning, C. D.

    1981-01-01

    Design and quality control of large superconducting magnets for reliability comparable to pressure vessels are discussed. The failure modes are analyzed including thermoelectric instabilities, electrical shorts, cryogenic/vacuum defects, and mechanical malfunctions. Design must take into consideration conductor stability, insulation based on the Paschen curves, and the possible burnout of cryogenic transition leads if the He flow is interrupted. The final stage of the metal drawing process should stress the superconductor material to a stress value higher than the magnet design stress, cabled conductors should be used to achieve mechanical redundancy, and ground-plane insulation must be multilayered for arc prevention.

  1. Gate-induced superconductivity in atomically thin MoS2 crystals.

    PubMed

    Costanzo, Davide; Jo, Sanghyun; Berger, Helmuth; Morpurgo, Alberto F

    2016-04-01

    When thinned down to the atomic scale, many layered van der Waals materials exhibit an interesting evolution of their electronic properties, whose main aspects can be accounted for by changes in the single-particle bandstructure. Phenomena driven by interactions are also observed, but identifying experimentally systematic trends in their thickness dependence is challenging. Here, we explore the evolution of gate-induced superconductivity in exfoliated MoS2 multilayers ranging from bulk-like to individual monolayers. We observe a clear transition for all thicknesses down to the ultimate atomic limit, providing the first demonstration of gate-induced superconductivity in atomically thin exfoliated crystals. Additionally, we characterize the superconducting state by measuring the critical temperature TC and magnetic field BC in a large number of multilayer devices while decreasing their thickness. We find that the superconducting properties exhibit a pronounced reduction in TC and BC when going from bilayers to monolayers, for which we discuss possible microscopic mechanisms.

  2. Applications of multilayer optics

    NASA Astrophysics Data System (ADS)

    Wang, Zhanshan; Zhu, Jingtao; Mu, Baozhong; Zhang, Zhong; Wang, Fengli; Xu, Jing; Li, Wenbin; Chen, Lingyan

    2010-11-01

    Recent development of multilayer mirror and its applications in extreme ultraviolet (EUV), soft X-ray ranges in China was reviewed in this paper. Three types of multilayer mirrors were developed with special performance for dense plasma diagnostics, EUV astronomical observation. Firstly, dual-periodic W/B 4C multilayer mirror was designed for Kirkpatrick-Baez (K-B) microscopy working at TiKα line (4.75 keV), which is highly reflective both at hard X-ray (CuKα line at 8.05 keV) and soft X-ray (4.75 keV). Using this mirror, the K-B system can be aligned conveniently in air using hard X-ray instead of in vacuum. The second mirror is aperiodic Mg/SiC multilayer, also a bi-functional mirror with high reflectivity for He-II emission line (30.4 nm) but suppressing He-I emission line (58.4 nm) in astronomy observation, which will replace the traditional combination of periodic multilayer and the fragile film filter. This will be more safe in satellite launching. The third mirror is Mo/Si periodic multilayer, depositing on a parabolic substrate with diameter of 230 mm, which is designed for EUV telescope for imaging of solar corona by selecting Fe-XII emission (19.5 nm). The uniformity of lateral layer thickness distribution is within ±0.3% along the diameter of mirror, measured by X-ray reflectometry. The measured peak reflectivity is 42% at the wavelength of 19.5 nm. All these multilayer mirrors were prepared by using magnetron sputtering system in our group.

  3. Simple Superconducting "Permanent" Electromagnet

    NASA Technical Reports Server (NTRS)

    Israelson, Ulf E.; Strayer, Donald M.

    1992-01-01

    Proposed short tube of high-temperature-superconducting material like YBa2Cu3O7 acts as strong electromagnet that flows as long as magnetic field remains below critical value and temperature of cylinder maintained sufficiently below superconducting-transition temperature. Design exploits maximally anisotropy of high-temperature-superconducting material.

  4. Searching for Superconductivity in Micrometeorites

    NASA Astrophysics Data System (ADS)

    Thiemens, M. H.; Guenon, S.; Ramirez, J. G.; Basaran, A. C.; Taylor, S.; Schuller, I.

    2014-12-01

    We have developed a very sensitive, highly selective, non-destructive technique for screening natural materials for the presence of superconductivity. This technique, based on phase sensitive detection of microwave absorption is capable of detecting 10-12 cm3of a superconductor embedded in a non-superconducting matrix. We applied our technique to search for superconductivity in micrometeorites, small extraterrestrial (ET) particles that add most of the ET mass to the present day Earth. We measured approximately 65 micrometeorites and compared their spectra with those of eight reference materials.Micrometeorites (MMs) are ideal samples with which to test our highly sensitive superconductivity probe, as individual MMs weigh 10-5 g and the large number of micrometeorites arriving on Earth, suggests some contain minerals formed under conditions that cannot be replicated in the laboratory. Minerals in meteorites formed during planetary processes associated with accretion/condensation, planetary differentiation, and segregation. Other components such as pre-solar grains, SiC, diamonds, graphite, Si3N4, and deuterium enriched organics formed under some of the most intense physical-chemical environments in the Universe, including supernovae and stellar outflows. It is during such severe processes that exotic superconducting species may have been created.The research presented here established the methodology and proved the ultrahigh sensitivity of the technique by detecting the presence of the Verwey-transition of the magnetite present in these micrometeorites. The investigated micrometeorites contained no superconducting phases. This work was supported by an AFOSR MURI grant no. F49550-09-1-0577.

  5. Focus on superconducting properties of iron chalcogenides

    NASA Astrophysics Data System (ADS)

    Takano, Yoshihiko

    2012-10-01

    Since the discovery of iron-based superconductors, much attention has been given to the exploration of new superconducting compounds. Numerous superconducting iron compounds have been found and categorized into five groups: LnFeAsO (Ln = lanthanide), BaFe2As2, KFeAs, FeSe and FeAs with perovskite blocking layers. Among them, FeSe has the simplest crystal structure. Since the crystal structure is composed of only superconducting Fe layers, the FeSe family must be the best material to investigate the mechanism of iron-based superconductivity. FeSe shows very strong pressure effects. The superconducting transition temperature (Tc) of FeSe is approximately 8 K at ambient pressure. However Tc dramatically increases up to 37 K under applied pressure of 4-6 GPa. This is the third highest Tc value among binary superconductors, surpassed only by CsC60 under pressure (Tc = 38 K) and MgB2 (Tc = 39 K). On the other hand, despite FeTe having a crystal structure analogous to that of FeSe, FeTe shows antiferromagnetic properties without superconductivity. Doping of small ions, either Se or S, however, can induce superconductivity in FeTe1-xSex or FeTe1-xSx . The superconductivity is very weak for small x values, and annealing under certain conditions is required to obtain strong superconductivity, for instance annealing in oxygen or alcoholic beverages such as red wine. The following selection of papers describe many important experimental and theoretical studies on iron chalcogenide superconductors including preparation of single crystals, bulk samples and thin films; NMR measurements; photoemission spectroscopy; high-pressure studies; annealing effects and research on new BiS2-based superconductors. I hope this focus issue will help researchers understand the frontiers of iron chalcogenide superconductors and assist in the discovery of new phenomena related to iron-based superconductivity.

  6. A statistical rationale for establishing process quality control limits using fixed sample size, for critical current verification of SSC superconducting wire

    NASA Astrophysics Data System (ADS)

    Pollock, D. A.; Brown, G.; Capone, D. W., II; Christopherson, D.; Seuntjens, J. M.; Woltz, J.

    1992-03-01

    The purpose of this paper is to demonstrate a statistical method for verifying superconducting wire process stability as represented by I(sub c). The paper does not propose changing the I(sub c) testing frequency for wire during Phase 1 of the present Vendor Qualification Program. The actual statistical limits demonstrated for one supplier's data are not expected to be suitable for all suppliers. However, the method used to develop the limits and the potential for improved process through their use, may be applied equally. Implementing the demonstrated method implies that the current practice of testing all pieces of wire from each billet, for the purpose of detecting manufacturing process errors (i.e. missing a heat-treatment cycle for a part of the billet, etc.) can be replaced by other less costly process control measures. As used in this paper, process control limits for critical current are quantitative indicators of the source manufacturing process uniformity. The limits serve as alarms indicating the need for manufacturing process investigation.

  7. Superconductivity in Medicine

    NASA Astrophysics Data System (ADS)

    Alonso, Jose R.; Antaya, Timothy A.

    2012-01-01

    Superconductivity is playing an increasingly important role in advanced medical technologies. Compact superconducting cyclotrons are emerging as powerful tools for external beam therapy with protons and carbon ions, and offer advantages of cost and size reduction in isotope production as well. Superconducting magnets in isocentric gantries reduce their size and weight to practical proportions. In diagnostic imaging, superconducting magnets have been crucial for the successful clinical implementation of magnetic resonance imaging. This article introduces each of those areas and describes the role which superconductivity is playing in them.

  8. Force sensitivity of multilayer graphene optomechanical devices

    PubMed Central

    Weber, P.; Güttinger, J.; Noury, A.; Vergara-Cruz, J.; Bachtold, A.

    2016-01-01

    Mechanical resonators based on low-dimensional materials are promising for force and mass sensing experiments. The force sensitivity in these ultra-light resonators is often limited by the imprecision in the measurement of the vibrations, the fluctuations of the mechanical resonant frequency and the heating induced by the measurement. Here, we strongly couple multilayer graphene resonators to superconducting cavities in order to achieve a displacement sensitivity of 1.3 fm Hz−1/2. This coupling also allows us to damp the resonator to an average phonon occupation of 7.2. Our best force sensitivity, 390 zN Hz−1/2 with a bandwidth of 200 Hz, is achieved by balancing measurement imprecision, optomechanical damping, and measurement-induced heating. Our results hold promise for studying the quantum capacitance of graphene, its magnetization, and the electron and nuclear spins of molecules adsorbed on its surface. PMID:27502017

  9. Force sensitivity of multilayer graphene optomechanical devices

    NASA Astrophysics Data System (ADS)

    Weber, P.; Güttinger, J.; Noury, A.; Vergara-Cruz, J.; Bachtold, A.

    2016-08-01

    Mechanical resonators based on low-dimensional materials are promising for force and mass sensing experiments. The force sensitivity in these ultra-light resonators is often limited by the imprecision in the measurement of the vibrations, the fluctuations of the mechanical resonant frequency and the heating induced by the measurement. Here, we strongly couple multilayer graphene resonators to superconducting cavities in order to achieve a displacement sensitivity of 1.3 fm Hz-1/2. This coupling also allows us to damp the resonator to an average phonon occupation of 7.2. Our best force sensitivity, 390 zN Hz-1/2 with a bandwidth of 200 Hz, is achieved by balancing measurement imprecision, optomechanical damping, and measurement-induced heating. Our results hold promise for studying the quantum capacitance of graphene, its magnetization, and the electron and nuclear spins of molecules adsorbed on its surface.

  10. Magnetic multilayer interface anisotropy

    SciTech Connect

    Pechan, M.J.

    1992-01-01

    Ni/Mo and Ni/V multilayer magnetic anisotropy has been investigated as a function of Ni layer thickness, frequency and temperature. Variable frequency ferromagnetic resonance (FMR) measurements show, for the first time, significant frequency dependence associated with the multilayer magnetic anisotropy. The thickness dependence allows one to extract the interface contribution from the total anisotropy. Temperature dependent FMR (9 GHz) and room temperature magnetization indicate that strain between Ni and the non-magnetic layers is contributing significantly to the source of the interface anisotropy and the state of the interfacial magnetization. In order to examine the interface properties of other transition metal multilayer systems, investigations on Fe/Cu are underway and CoCr/Ag is being proposed. ESR measurements have been reported on Gd substituted YBaCuO superconductors and a novel quasi-equilibrium method has been developed to determine quickly and precisely the ransition temperature.

  11. Protective link for superconducting coil

    DOEpatents

    Umans, Stephen D.

    2009-12-08

    A superconducting coil system includes a superconducting coil and a protective link of superconducting material coupled to the superconducting coil. A rotating machine includes first and second coils and a protective link of superconducting material. The second coil is operable to rotate with respect to the first coil. One of the first and second coils is a superconducting coil. The protective link is coupled to the superconducting coil.

  12. Transport Anomalies and Possible High Tc Superconductivity in interconnected multiwall carbon nanotube sheets doped by ion implantation

    NASA Astrophysics Data System (ADS)

    Zakhidov, Anvar; Howard, Austin; Cornell, Nicholas; Goskun, Ulas; Salamon, Myron; Baughman, Ray; Bykova, Julia; Mayo, Nathanael; Wang, Xuemei; Galstyan, Eduard; Freyhardt, Herbert; Kan Chu, Wei

    2012-02-01

    Ion implantation offers an alternative doping method. In searching for superconductivity,we describe here the ion-implantation doping of MWCNT interconnected networks by boron and other dopants (phosphorous, sulfur, arsenic) and report transport anomalies in oriented networks of ion implanted MWCNT sheets as compared to cross coated (non-oriented multilayer MWCNT sheets). The strong drop of resistance R(T) with temperature decrease starting at Tc1= 50-60 K and even at higher T is reminiscent of inhomogeneous superconducting islands appearing in the non-SC matrix. An unusual anomaly of the 4-terminal resistance is observed in many samples, R(T) becoming negative at lower T< Tc2 ˜ 10-20 K, This negative resistance is found to be associated with unusual I-V curves with s-shape at low T < Tc2 and R(T) shows nonlinear dependence on excitation current and other features that are studied carefully in MWCNTs with different lengths and densities. This negative-resistance behavior gives a hint for the possible incorporation of superconducting areas and can be explained in terms of an imbalanced resistance bridge.

  13. Superconductivity in transition metals.

    PubMed

    Slocombe, Daniel R; Kuznetsov, Vladimir L; Grochala, Wojciech; Williams, Robert J P; Edwards, Peter P

    2015-03-13

    A qualitative account of the occurrence and magnitude of superconductivity in the transition metals is presented, with a primary emphasis on elements of the first row. Correlations of the important parameters of the Bardeen-Cooper-Schrieffer theory of superconductivity are highlighted with respect to the number of d-shell electrons per atom of the transition elements. The relation between the systematics of superconductivity in the transition metals and the periodic table high-lights the importance of short-range or chemical bonding on the remarkable natural phenomenon of superconductivity in the chemical elements. A relationship between superconductivity and lattice instability appears naturally as a balance and competition between localized covalent bonding and so-called broken covalency, which favours d-electron delocalization and superconductivity. In this manner, the systematics of superconductivity and various other physical properties of the transition elements are related and unified.

  14. Dissipative hydride precipitates in superconducting niobium cavities

    SciTech Connect

    Romanenko, A.; Cooley, L.D.; Ciovati, G.; Wu, G.; /Argonne

    2011-10-01

    We report the first direct observation of the microstructural features exhibiting RF losses at high surface magnetic fields of above 100 mT in field emission free superconducting niobium cavities. The lossy areas were identified by advanced thermometry. Surface investigations using different techniques were carried out on cutout samples from lossy areas and showed the presence of dendritic niobium hydrides. This finding has possible implications to the mechanisms of RF losses in superconducting niobium at all field levels.

  15. Interpretation of transmission through type II superconducting thin film on dielectric substrate as observed by laser thermal spectroscopy

    NASA Astrophysics Data System (ADS)

    Šindler, M.; Tesař, R.; Koláček, J.; Skrbek, L.

    2012-12-01

    We provide a thorough analysis of THz properties of BCS-like superconducting thin films. Temperature and frequency dependence of complex conductivity in zero magnetic field is discussed by utilizing the Zimmerman et al. explicit BCS based formula [Physica C 183 (1991) 99]. We extend this approach by employing the effective medium theory and develop a phenomenological model capable of accounting for the influence of external magnetic field. Using Yeh powerful formalism [Surface Sci. 96 (1980) 41] we calculate optical transmission of linearly polarized laser beam normally incident to a multilayered sample consisting of a thin NbN film grown on birefringent sapphire substrate, entirely covering ranges of interest in temperature and frequency. A proposal to exploit linear polarization of the incident beam parallel with principal axes of conductivity tensor is explained and theoretical predictions for a realistic NbN sample are computed and discussed.

  16. MICROSTRUCTURE OF SUPERCONDUCTING MGB(2).

    SciTech Connect

    ZHU,Y.; LI,Q.; WU,L.; VOLKOV,V.; GU,G.; MOODENBAUGH,A.R.

    2001-07-12

    Recently, Akimitsu and co-workers [1] discovered superconductivity at 39 K in the intermetallic compound MgB{sub 2}. This discovery provides a new perspective on the mechanism for superconductivity. More specifically, it opens up possibilities for investigation of structure/properties in a new class of materials. With the exceptions of the cuprate and C{sub 60} families of compounds, MgB{sub 2} possesses the highest superconducting transition temperature T{sub c}. Its superconductivity appears to follow the BCS theory, apparently being mediated by electron-phonon coupling. The coherence length of MgB{sub 2} is reported to be longer than that of the cuprates [2]. In contrast to the cuprates, grain boundaries are strongly coupled and current density is determined by flux pinning [2,3]. Presently, samples of MgB{sub 2} commonly display inhomogeneity and porosity on the nanoscale, and are untextured. In spite of these obstacles, magnetization and transport measurements show that polycrystalline samples may carry large current densities circulating across many grains [3,4]. Very high values of critical current densities and critical fields have been recently observed in thin films [5,6]. These attributes suggest possible large scale and electronic applications. The underlying microstructure can be intriguing, both in terms of basic science and in applied areas. Subsequent to the discovery, many papers were published [1-13], most dealing with synthesis, physical properties, and theory. There have yet been few studies of microstructure and structural defects [11, 14]. A thorough understanding of practical superconducting properties can only be developed after an understanding of microstructure is gained. In this work we review transmission electron microscopy (TEM) studies of sintered MgB{sub 2} pellets [14]. Structural defects, including second phase particles, dislocations, stacking faults, and grain boundaries, are analyzed using electron diffraction, electron

  17. High Temperature Superconducting Films and Multilayers for Electronics

    DTIC Science & Technology

    1992-02-20

    COSATI CODES 18. SUBJECT TERMS (Continue on reverse if necenery and identify by block number) FIELD GROUP SUB-GROUP superconductors, yttrium , barium...Experiments were performed to synthesize Ca- doped YBCO films (10% of the Y replaced by Ca) with a 1:2:4 structure and composition. This material was...with SrTiO3 is its high real and imaginary dielectric constants which slow and attenuate signals. The resistivity of epitaxial LaAIO 3 films was four

  18. High Temperature Superconducting Films and Multilayers for Electronics

    DTIC Science & Technology

    1993-02-20

    GROUP SUB-GROUP superconductors, yttrium , barium, copper, oxides, high, ’ critical, temperature, thin films, tunneling, barriers, sputtering 19. ABSTRACT...levels of a stabilizing element into the film’s crystal structure (i.e. " doping *). During this reporting period the effect of using very low...crystallization temperatures and also doping known superconductors with various elements have been studied. Although no enhancements in T ’s above those presently

  19. Superconducting composite with multilayer patterns and multiple buffer layers

    DOEpatents

    Wu, X.D.; Muenchausen, R.E.

    1993-10-12

    An article of manufacture is described including a substrate, a patterned interlayer of a material selected from the group consisting of magnesium oxide, barium-titanium oxide or barium-zirconium oxide, the patterned interlayer material overcoated with a secondary interlayer material of yttria-stabilized zirconia or magnesium-aluminum oxide, upon the surface of the substrate whereby an intermediate article with an exposed surface of both the overcoated patterned interlayer and the substrate is formed, a coating of a buffer layer selected from the group consisting of cerium oxide, yttrium oxide, curium oxide, dysprosium oxide, erbium oxide, europium oxide, iron oxide, gadolinium oxide, holmium oxide, indium oxide, lanthanum oxide, manganese oxide, lutetium oxide, neodymium oxide, praseodymium oxide, plutonium oxide, samarium oxide, terbium oxide, thallium oxide, thulium oxide, yttrium oxide and ytterbium oxide over the entire exposed surface of the intermediate article, and, a ceramic superconductor. 5 figures.

  20. High Temperature Superconducting Films and Multilayers for Electronics

    DTIC Science & Technology

    1994-04-19

    earth -Cu-O .................... 81 MP - Melt processing . ........... 97 td - tangent delta meas ..................... 107 BS - Bi-Sr-(Ca)-Cu-O...34V. For sapphire and YSZ, fthe lattice spacing isth lengfth of a diagonal in the two-dimenskonal surface lattice Owa lies Iparalki ID a < 100...and the plasma edge, this behavior reproducible in both the cooling and warm - we measured the reflectance at each temperature up to ing process. At

  1. Influence of spin-polarized current on superconductivity and the realization of large magnetoresistance.

    PubMed

    Miao, Guo-Xing; Yoon, Kapsoo; Santos, Tiffany S; Moodera, Jagadeesh S

    2007-06-29

    The superconducting state can be influenced by injecting spin-polarized current in a controlled manner by properly tailoring the interfacial transmittivity between a ferromagnet (F) and a superconductor (S), resulting in a large magnetoresistance of over 1100% for a F/I/S/I/F multilayer system (I insulator). Because of the competition between ferromagnetism and superconductivity, the superconducting transition temperature (T(C)) in the spin-parallel configuration is shifted below that in the spin antiparallel configuration. The T(C) shift is attributed to ferromagnet-induced nonequilibrium spin carriers in the superconductors.

  2. Domain-wall guided nucleation of superconductivity in hybrid ferromagnet-superconductor-ferromagnet layered structures.

    PubMed

    Gillijns, W; Aladyshkin, A Yu; Lange, M; Van Bael, M J; Moshchalkov, V V

    2005-11-25

    Domain-wall superconductivity is studied in a superconducting Nb film placed between two ferromagnetic Co/Pd multilayers with perpendicular magnetization. The parameters of top and bottom ferromagnetic films are chosen to provide different coercive fields, so that the magnetic domain structure of the ferromagnets can be selectively controlled. From the dependence of the critical temperature Tc on the applied magnetic field H, we have found evidence for domain-wall superconductivity in this three-layered F/S/F structure for different magnetic domain patterns. The phase boundary, calculated numerically for this structure from the linearized Ginzburg-Landau equation, is in good agreement with the experimental data.

  3. Multilayer Perceptrons for Classification

    DTIC Science & Technology

    1992-03-01

    retention/ separation rates fu, input to force projection models. The second application concerns the classification of Armor Piercing Incendiary (API...Air Force pilot reten- tion/ separation rates for input to force projection models. The second application concerns the classification of Armor...methodologies for predicting pilot retention/ separation rates for input to personnel inventory projection models were e::plored. Specifically, the multilayer

  4. Superconductive niobium films coating carbon nanotube fibers

    NASA Astrophysics Data System (ADS)

    Salvato, M.; Lucci, M.; Ottaviani, I.; Cirillo, M.; Behabtu, N.; Young, C. C.; Pasquali, M.; Vecchione, A.; Fittipaldi, R.; Corato, V.

    2014-11-01

    Superconducting niobium (Nb) has been successfully obtained by sputter deposition on carbon nanotube fibers. The transport properties of the niobium coating the fibers are compared to those of niobium thin films deposited on oxidized Si substrates during the same deposition run. For niobium films with thicknesses above 300 nm, the niobium coating the fibers and the thin films show similar normal state and superconducting properties with critical current density, measured at T = 4.2 K, of the order of 105 A cm-2. Thinner niobium layers coating the fibers also show the onset of the superconducting transition in the resistivity versus temperature dependence, but zero resistance is not observed down to T = 1 K. We evidence by scanning electron microscopy (SEM) and current-voltage measurements that the granular structure of the samples is the main reason for the lack of true global superconductivity for thicknesses below 300 nm.

  5. Superconductive radiofrequency window assembly

    DOEpatents

    Phillips, H.L.; Elliott, T.S.

    1998-05-19

    The present invention is a superconducting radiofrequency window assembly for use in an electron beam accelerator. The SRF window assembly has a superconducting metal-ceramic design. The SRF window assembly comprises a superconducting frame, a ceramic plate having a superconducting metallized area, and a superconducting eyelet for sealing plate into frame. The plate is brazed to eyelet which is then electron beam welded to frame. A method for providing a ceramic object mounted in a metal member to withstand cryogenic temperatures is also provided. The method involves a new metallization process for coating a selected area of a ceramic object with a thin film of a superconducting material. Finally, a method for assembling an electron beam accelerator cavity utilizing the SRF window assembly is provided. The procedure is carried out within an ultra clean room to minimize exposure to particulates which adversely affect the performance of the cavity within the electron beam accelerator. 11 figs.

  6. Superconducting radiofrequency window assembly

    DOEpatents

    Phillips, H.L.; Elliott, T.S.

    1997-03-11

    The present invention is a superconducting radiofrequency window assembly for use in an electron beam accelerator. The srf window assembly has a superconducting metal-ceramic design. The srf window assembly comprises a superconducting frame, a ceramic plate having a superconducting metallized area, and a superconducting eyelet for sealing plate into frame. The plate is brazed to eyelet which is then electron beam welded to frame. A method for providing a ceramic object mounted in a metal member to withstand cryogenic temperatures is also provided. The method involves a new metallization process for coating a selected area of a ceramic object with a thin film of a superconducting material. Finally, a method for assembling an electron beam accelerator cavity utilizing the srf window assembly is provided. The procedure is carried out within an ultra clean room to minimize exposure to particulates which adversely affect the performance of the cavity within the electron beam accelerator. 11 figs.

  7. Release-rate calorimetry of multilayered materials for aircraft seats

    NASA Technical Reports Server (NTRS)

    Fewell, L. L.; Parker, J. A.; Duskin, F.; Speith, H.; Trabold, E.

    1980-01-01

    Multilayered samples of contemporary and improved fire-resistant aircraft seat materials were evaluated for their rates of heat release and smoke generation. Top layers with glass-fiber block cushion were evaluated to determine which materials, based on their minimum contributions to the total heat release of the multilayered assembly, may be added or deleted. The smoke and heat release rates of multilayered seat materials were then measured at heat fluxes of 1.5 and 3.5 W/cm2. Abrasion tests were conducted on the decorative fabric covering and slip sheet to ascertain service life and compatibility of layers

  8. High Temperature Superconducting Materials Database

    National Institute of Standards and Technology Data Gateway

    SRD 149 NIST High Temperature Superconducting Materials Database (Web, free access)   The NIST High Temperature Superconducting Materials Database (WebHTS) provides evaluated thermal, mechanical, and superconducting property data for oxides and other nonconventional superconductors.

  9. Superconducting energy recovery linacs

    NASA Astrophysics Data System (ADS)

    Ben-Zvi, Ilan

    2016-10-01

    High-average-power and high-brightness electron beams from a combination of laser photocathode electron guns and a superconducting energy recovery linac (ERL) is an emerging accelerator science with applications in ERL light sources, high repetition rate free electron lasers , electron cooling, electron ion colliders and more. This paper reviews the accelerator physics issues of superconducting ERLs, discusses major subsystems and provides a few examples of superconducting ERLs.

  10. Superconductive imaging surface magnetometer

    DOEpatents

    Overton, Jr., William C.; van Hulsteyn, David B.; Flynn, Edward R.

    1991-01-01

    An improved pick-up coil system for use with Superconducting Quantum Interference Device gradiometers and magnetometers involving the use of superconducting plates near conventional pick-up coil arrangements to provide imaging of nearby dipole sources and to deflect environmental magnetic noise away from the pick-up coils. This allows the practice of gradiometry and magnetometry in magnetically unshielded environments. One embodiment uses a hemispherically shaped superconducting plate with interior pick-up coils, allowing brain wave measurements to be made on human patients. another embodiment using flat superconducting plates could be used in non-destructive evaluation of materials.

  11. Superconducting optical modulator

    NASA Astrophysics Data System (ADS)

    Bunt, Patricia S.; Ference, Thomas G.; Puzey, Kenneth A.; Tanner, David B.; Tache, Nacira; Varhue, Walter J.

    2000-12-01

    An optical modulator based on the physical properties of high temperature superconductors has been fabricated and tested. The modulator was constructed form a film of Yttrium Barium Copper Oxide (YBCO) grown on undoped silicon with a buffer layer of Yttria Stabilized Zirconia. Standard lithographic procedures were used to pattern the superconducting film into a micro bridge. Optical modulation was achieved by passing IR light through the composite structure normal to the micro bridge and switching the superconducting film in the bridge region between the superconducting and non-superconducting states. In the superconducting state, IR light reflects from the superconducting film surface. When a critical current is passed through the micro bridge, it causes the film in this region to switch to the non-superconducting state allowing IR light to pass through it. Superconducting materials have the potential to switch between these two states at speeds up to 1 picosecond using electrical current. Presently, fiber optic transmission capacity is limited by the rate at which optical data can be modulated. The superconducting modulator, when combined with other components, may have the potential to increase the transmission capacity of fiber optic lines.

  12. Multilayer optics for femtosecond-diffractometry

    NASA Astrophysics Data System (ADS)

    Wiesmann, J.; Hertlein, F.; Michaelsen, C.

    2009-08-01

    X-ray sources according to the principle of the "free electron laser" (FEL), will in future, be able to provide bright radiation with pulses in the femtosecond range. Even nowadays, home-lab X-ray sources with very short pulses in the sub-picosecond range are already available for lab experiments. These laser-based sources need different kinds of optics to direct the emitted X-rays onto the samples. On the one hand, the optics should transfer as much flux as possible and on the other hand, the brilliance and timestructure of the source should not be reduced too much. These requirements are fulfilled with 2-dimensional beam shaping multilayer optics. Their design, production and their influence on the shape of the X-ray beam will be explained in this contribution. The optics consist of bent substrates with shape tolerances below 100 nm, upon which multilayers are deposited with single layer thicknesses in the nanometer range and up to several hundreds of pairs of layers. Furthermore, these multilayers were designed with lateral thickness gradients within +/- 1% deviation of the ideal shape. This means that a deposition precision in the picometer range is required. We use magnetron sputtering methods for deposition, optical profilometry in order to characterize the shape of the optics and X-ray reflectometry to characterize the multilayers.

  13. Stoichiometry and thickness dependence of superconducting properties of niobium nitride thin films

    SciTech Connect

    Beebe, Melissa R. Beringer, Douglas B.; Burton, Matthew C.; Yang, Kaida; Lukaszew, R. Alejandra

    2016-03-15

    The current technology used in linear particle accelerators is based on superconducting radio frequency (SRF) cavities fabricated from bulk niobium (Nb), which have smaller surface resistance and therefore dissipate less energy than traditional nonsuperconducting copper cavities. Using bulk Nb for the cavities has several advantages, which are discussed elsewhere; however, such SRF cavities have a material-dependent accelerating gradient limit. In order to overcome this fundamental limit, a multilayered coating has been proposed using layers of insulating and superconducting material applied to the interior surface of the cavity. The key to this multilayered model is to use superconducting thin films to exploit the potential field enhancement when these films are thinner than their London penetration depth. Such field enhancement has been demonstrated in MgB{sub 2} thin films; here, the authors consider films of another type-II superconductor, niobium nitride (NbN). The authors present their work correlating stoichiometry and superconducting properties in NbN thin films and discuss the thickness dependence of their superconducting properties, which is important for their potential use in the proposed multilayer structure. While there are some previous studies on the relationship between stoichiometry and critical temperature T{sub C}, the authors are the first to report on the correlation between stoichiometry and the lower critical field H{sub C1}.

  14. Multilayer Optical Learning Networks

    NASA Astrophysics Data System (ADS)

    Wagner, Kelvin; Psaltis, Demetri

    1987-08-01

    In this paper we present a new approach to learning in a multilayer optical neural network which is based on holographically interconnected nonlinear Fabry-Perot etalons. The network can learn the interconnections that form a distributed representation of a desired pattern transformation operation. The interconnections are formed in an adaptive and self aligning fashion, as volume holographic gratings in photorefractive crystals. Parallel arrays of globally space integrated inner products diffracted by the interconnecting hologram illuminate arrays of nonlinear Fabry-Perot etalons for fast thresholding of the transformed patterns. A phase conjugated reference wave interferes with a backwards propagating error signal to form holographic interference patterns which are time integrated in the volume of the photorefractive crystal in order to slowly modify and learn the appropriate self aligning interconnections. A holographic implementation of a single layer perceptron learning procedure is presented that can be extendept ,to a multilayer learning network through an optical implementation of the backward error propagation (BEP) algorithm.

  15. Research & Development on Superconducting Niobium Materials via Magnetic Measurements

    SciTech Connect

    S. B. Roy, V. C. Sahni, and G. R. Myneni

    2011-03-01

    We present a study of superconducting properties of both large grain (1 mm average grain size) and small grain (50 micron average grain size) Niobium materials containing varying amounts of Tantalum impurities that have been used in the fabrication of high accelerating gradient superconducting radio frequency cavities. We found that a buffered chemical polishing of these Niobium samples causes a distinct reduction in the superconducting parameters like TC, wt- ppm to 1300 wt-ppm. Implications of these results on the performance of niobium superconducting radio frequency cavities are discussed, especially the anomalous high field RF losses that have been reported in the literature.

  16. Magnetic properties of superconducting Bi/Ni bilayers

    NASA Astrophysics Data System (ADS)

    Zhou, Hexin; Gong, Xinxin; Jin, Xiaofeng

    2017-01-01

    The magnetic properties of an unexpected superconducting bilayer consisting of non-superconducting Bi and ferromagnetic Ni have been investigated. A large magnetization signal is observed when the sample is cooled below the superconducting transition temperature in zero magnetic field, which has the same direction with the magnetization of the adjacent Ni layer. Interestingly, this Bi/Ni bilayer shows opposite responses to external magnetic field in zero field cooling (ZFC) process and field cooling (FC) process. It behaves diamagnetically in ZFC while paramagnetically in FC. Besides, magnetic hysteresis loops below the superconducting transition temperature show flux pinning and flux jumping effects.

  17. Flux trapping in superconducting thin films in weak magnetic fields

    NASA Astrophysics Data System (ADS)

    Geng, Q.; Goto, E.

    1993-11-01

    Magnetic-field distribution measurements over a patterned superconducting strip line sample were conducted using a superconducting quantum interference device pickup coil, showing that, in the range of 500 μG-50 mG of perpendicular magnetic field B⊥,i, the superconducting films record previous magnetic histories precisely. The magnetic-field distribution with a field B⊥,i applied at all times is identical to one with no field applied at any time. A calculation based on the flux trapping model explains these results indicating that all the magnetic fluxes penetrate the superconducting thin films.

  18. Superconductivity in aromatic hydrocarbons

    NASA Astrophysics Data System (ADS)

    Kubozono, Yoshihiro; Goto, Hidenori; Jabuchi, Taihei; Yokoya, Takayoshi; Kambe, Takashi; Sakai, Yusuke; Izumi, Masanari; Zheng, Lu; Hamao, Shino; Nguyen, Huyen L. T.; Sakata, Masafumi; Kagayama, Tomoko; Shimizu, Katsuya

    2015-07-01

    'Aromatic hydrocarbon' implies an organic molecule that satisfies the (4n + 2) π-electron rule and consists of benzene rings. Doping solid aromatic hydrocarbons with metals provides the superconductivity. The first discovery of such superconductivity was made for K-doped picene (Kxpicene, five benzene rings). Its superconducting transition temperatures (Tc's) were 7 and 18 K. Recently, we found a new superconducting Kxpicene phase with a Tc as high as 14 K, so we now know that Kxpicene possesses multiple superconducting phases. Besides Kxpicene, we discovered new superconductors such as Rbxpicene and Caxpicene. A most serious problem is that the shielding fraction is ⩽15% for Kxpicene and Rbxpicene, and it is often ∼1% for other superconductors. Such low shielding fractions have made it difficult to determine the crystal structures of superconducting phases. Nevertheless, many research groups have expended a great deal of effort to make high quality hydrocarbon superconductors in the five years since the discovery of hydrocarbon superconductivity. At the present stage, superconductivity is observed in certain metal-doped aromatic hydrocarbons (picene, phenanthrene and dibenzopentacene), but the shielding fraction remains stubbornly low. The highest priority research area is to prepare aromatic superconductors with a high superconducting volume-fraction. Despite these difficulties, aromatic superconductivity is still a core research target and presents interesting and potentially breakthrough challenges, such as the positive pressure dependence of Tc that is clearly observed in some phases of aromatic hydrocarbon superconductors, suggesting behavior not explained by the standard BCS picture of superconductivity. In this article, we describe the present status of this research field, and discuss its future prospects.

  19. Superconducting phase in UGe2 by AC calorimetry

    NASA Astrophysics Data System (ADS)

    Taufour, Valentin; Aoki, Dai; Knebel, Georg; Flouquet, Jacques

    2012-12-01

    We report on the detection of the superconducting transition Tsc in the superconducting ferromagnet UGe2 by AC calorimetry under pressure. Our results confirm the small value of the specific heat jump. We suggest that this observation is intrinsic in origin and does not arises from a distribution of Tsc due to pressure gradient or sample defects.

  20. Superconducting properties of protactinium.

    PubMed

    Smith, J L; Spirlet, J C; Müller, W

    1979-07-13

    The superconducting transition temperature and upper critical magnetic field of protactinium were measured by alternating-current susceptibility techniques. Since the superconducting behavior of protactinium is affected by its 5f electron character, it is clear now that protactinium is a true actinide element.

  1. Superconductivity of magnesium diboride

    DOE PAGES

    Bud’ko, Sergey L.; Canfield, Paul C.

    2015-07-15

    Over the past 14 years MgB2 has gone from a startling discovery to a promising, applied superconductor. In our article we present a brief overview of the synthesis and the basic superconducting properties of this remarkable compound. Specifically, the effect of pressure, substitutions and neutron irradiation on superconducting properties are discussed.

  2. Superconductivity of magnesium diboride

    SciTech Connect

    Bud’ko, Sergey L.; Canfield, Paul C.

    2015-07-15

    Over the past 14 years MgB2 has gone from a startling discovery to a promising, applied superconductor. In our article we present a brief overview of the synthesis and the basic superconducting properties of this remarkable compound. Specifically, the effect of pressure, substitutions and neutron irradiation on superconducting properties are discussed.

  3. Superconducting gyroscope research

    NASA Technical Reports Server (NTRS)

    Hendricks, J. B.; Karr, G. R.

    1985-01-01

    Four basic areas of research and development of superconducting gyroscopes are studied. Chapter 1 studies the analysis of a SQUID readout for a superconducting gyroscope. Chapter 2 studies the dependence of spin-up torque on channel and gas properties. Chapter 3 studies the theory of super fluid plug operation. And chapter 4 studies the gyro rotor and housing manufacture.

  4. BNL Direct Wind Superconducting Magnets

    SciTech Connect

    Parker, B.; Anerella, M.; Escallier, J.; Ghosh, A.; Jain, A.; Marone, A.; Muratore, A.; Wanderer, P.

    2011-09-12

    BNL developed Direct Wind magnet technology is used to create a variety of complex multi-functional multi-layer superconducting coil structures without the need for creating custom production tooling and fixturing for each new project. Our Direct Wind process naturally integrates prestress into the coil structure so external coil collars and yokes are not needed; the final coil package transverse size can then be very compact. Direct Wind magnets are produced with very good field quality via corrections applied during the course of coil winding. The HERA-II and BEPC-II Interaction Region (IR) magnet, J-PARC corrector and Alpha antihydrogen magnetic trap magnets and our BTeV corrector magnet design are discussed here along with a full length ILC IR prototype magnet presently in production and the coils that were wound for an ATF2 upgrade at KEK. A new IR septum magnet design concept for a 6.2 T combined-function IR magnet for eRHIC, a future RHIC upgrade, is introduced here.

  5. Heat Transfer in High Temperature Multilayer Insulation

    NASA Technical Reports Server (NTRS)

    Daryabeigi, Kamran; Miller, Steve D.; Cunnington, George R.

    2007-01-01

    High temperature multilayer insulations have been investigated as an effective component of thermal-protection systems for atmospheric re-entry of reusable launch vehicles. Heat transfer in multilayer insulations consisting of thin, gold-coated, ceramic reflective foils and Saffil(TradeMark) fibrous insulation spacers was studied both numerically and experimentally. A finite volume numerical thermal model using combined conduction (gaseous and solid) and radiation in porous media was developed. A two-flux model with anisotropic scattering was used for radiation heat transfer in the fibrous insulation spacers between the reflective foils. The thermal model was validated by comparison with effective thermal conductivity measurements in an apparatus based on ASTM standard C201. Measurements were performed at environmental pressures in the range from 1x10(exp -4) to 760 torr over the temperature range from 300 to 1300 K. Four multilayer samples with nominal densities of 48 kg/cu m were tested. The first sample was 13.3 mm thick and had four evenly spaced reflective foils. The other three samples were 26.6 mm thick and utilized either one, two, or four reflective foils, located near the hot boundary with nominal foil spacing of 1.7 mm. The validated thermal model was then used to study relevant design parameters, such as reflective foil spacing and location in the stack-up and coating of one or both sides of foils.

  6. High-Resolution Hard X-Ray and Gamma-Ray Spectrometers Based on Superconducting Absorbers Coupled to Superconducting Transition Edge Sensors

    SciTech Connect

    van den Berg, M.; Chow, D.; Loshak, A.; Cunningham, M.F.; Barbee, T.W.; Matthias, F.; Labov, S.E.

    2000-09-21

    We are developing detectors based on bulk superconducting absorbers coupled to superconducting transition edge sensors (TES) for high-resolution spectroscopy of hard X-rays and soft gamma-rays. We have achieved an energy resolution of 70 eV FWHM at 60 keV using a 1 x 1 x 0.25 mm{sup 3} Sn absorber coupled to a Mo/Cu multilayer TES with a transition temperature of 100 mK. The response of the detector is compared with a simple model using only material properties data and characteristics derived from IV-measurements. We have also manufactured detectors using superconducting absorbers with a higher stopping power, such as Pb and Ta. We present our first measurements of these detectors, including the thermalization characteristics of the bulk superconducting absorbers. The differences in performance between the detectors are discussed and an outline of the future direction of our detector development efforts is given.

  7. Superconductivity in carbon nanomaterials

    NASA Astrophysics Data System (ADS)

    Dlugon, Katarzyna

    The purpose of this thesis is to explain the phenomenon of superconductivity in carbon nanomaterials such as graphene, fullerenes and carbon nanotubes. In the introductory chapter, there is a description of superconductivity and how it occurs at critical temperature (Tc) that is characteristic and different to every superconducting material. The discovery of superconductivity in mercury in 1911 by Dutch physicist Heike Kamerlingh Onnes is also mentioned. Different types of superconductors, type I and type II, low and high temperatures superconductors, as well as the BCS theory that was developed in 1957 by Bardeen, Cooper, and Schrieffer, are also described in detail. The BCS theory explains how Cooper's pairs are formed and how they are responsible for the superconducting properties of many materials. The following chapters explain superconductivity in doped fullerenes, graphene and carbon nanotubes, respectively. There is a thorough explanation followed by many examples of different types of carbon nanomaterials in which small changes in chemical structure cause significant changes in superconducting properties. The goal of this research was not only to take into consideration well known carbon based superconductors but also to search for the newest available materials such as the fullerene nanowhiskers discovered quite recently. There is also a presentation of fairly new ideas about inducing superconductivity in a monolayer of graphene which is more challenging than inducing superconductivity in graphite by simply intercalating metal atoms between its graphene sheets. An effort has been taken to look for any available information about carbon nanomaterials that have the potential to superconduct at room temperature, mainly because discovery of such materials would be a real revolution in the modern world, although no such materials have been discovered yet.

  8. Phase stability in metallic multilayers

    NASA Astrophysics Data System (ADS)

    Genc, Arda

    As the thin film materials used in electronic and optical applications continue to decrease in thickness to the nano-scales, marked changes in functional properties are expected to occur due to changes in crystal structure of these materials. Therefore, such multilayer systems have been of considerable interest due to the ability to control properties by engineering the structure of materials at these scales. The new characterization tools allow direct imaging and analysis of such materials in order to link the performance variations with the crystal structure variations. Transmission Electron Microscopy (TEM) has been often the technique of choice in characterization of nanomaterials enabling not only imaging the structure of the material but also chemically probing of the composition changes at a high spatial resolution. The ultimate resolution achievable in the electron microscope is a product of both microscope and the specimen and the simultaneous effect of each defines the quality and quantity of the information transferred through the microscope. In this sense, the common ion-beam assisted TEM sample preparation techniques have been deeply recognized as being surface damaging at high ion milling energies (>5kV) thus limiting the information transfer in the microscope. For the first time, a low energy (<2kV) focused Ar ion beam milling system has been applied to remove the surface artifacts created by the high energy conventional broad Ar or focused Ga beam milling techniques. The overall quality of the samples drastically improved after the application of the low energy milling practices and the outcome results directly enhanced the clarity of the information gathered at the atomic and nanoscale by the electron microscope. Besides the specimen the resolution achievable in the electron microscope is strongly limited by the imperfections in the electron optics of the microscope column such as the spherical aberration of the electromagnetic lenses. Recently

  9. Release-rate calorimetry of multilayered materials for aircraft seats

    NASA Technical Reports Server (NTRS)

    Fewell, L. L.; Parker, J. A.; Duskin, F.; Spieth, H.; Trabold, E.

    1980-01-01

    Multilayered samples of contemporary and improved fire-resistant aircraft seat materials (foam cushion, decorative fabric, slip sheet, fire-blocking layer, and cushion-reinforcement layer) were evaluated for their rates of heat release and smoke generation. Top layers (decorative fabric, slip sheet, fire blocking, and cushion reinforcement) with glass-fiber block cushion were evaluated to determine which materials, based on their minimum contributions to the total heat release of the multilayered assembly, may be added or deleted. Top layers exhibiting desirable burning profiles were combined with foam cushion materials. The smoke and heat-release rate of multilayered seat materials were then measured at heat fluxes of 1.5 and 3.5 W/sq cm. Choices of contact and silicon adhesives for bonding multilayered assemblies were based on flammability, burn and smoke generation, animal toxicity tests, and thermal gravimetric analysis.

  10. Superconductivity in bundles of double-wall carbon nanotubes.

    PubMed

    Shi, Wu; Wang, Zhe; Zhang, Qiucen; Zheng, Yuan; Ieong, Chao; He, Mingquan; Lortz, Rolf; Cai, Yuan; Wang, Ning; Zhang, Ting; Zhang, Haijing; Tang, Zikang; Sheng, Ping; Muramatsu, Hiroyuki; Kim, Yoong Ahm; Endo, Morinobu; Araujo, Paulo T; Dresselhaus, Mildred S

    2012-01-01

    We present electrical and thermal specific heat measurements that show superconductivity in double-wall carbon nanotube (DWCNT) bundles. Clear evidence, comprising a resistance drop as a function of temperature, magnetoresistance and differential resistance signature of the supercurrent, suggest an intrinsic superconducting transition below 6.8 K for one particular sample. Additional electrical data not only confirm the existence of superconductivity, but also indicate the T(c) distribution that can arise from the diversity in the diameter and chirality of the DWCNTs. A broad superconducting anomaly is observed in the specific heat of a bulk DWCNT sample, which yields a T(c) distribution that correlates well with the range of the distribution obtained from the electrical data. As quasi one dimensionality of the DWCNTs dictates the existence of electronic density of state peaks, confirmation of superconductivity in this material system opens the exciting possibility of tuning the T(c) through the application of a gate voltage.

  11. Metal optics and superconductivity

    SciTech Connect

    Golovashkin, A.L.

    1989-01-01

    The articles contained in this collection are dedicated to the study of the electron structure of transition metals and superconducting alloys and compounds based on them. The study of the electron structure of materials is one of the central problems of solid-state physics and defines the solution of a number of problems. One of them is the problem of high-temperature superconductivity which has attracted exceptional attention from physicists in connection with the discovery of new classes of ceramic oxides which are superconducting at liquid-nitrogen temperature. The electron structure is one of the three whales on which all of superconductivity rests. It is frequently our ignorance of the electronic properties of a metal, alloy or compound in its normal state which makes it impossible to predict superconductivity in the material, preventing use from calculating the parameters of the superconducting state. There are now a number of effective methods for investigation of the electron structure of the metals and allows. This collection discusses metal optics, tunneling and magnetic measurements in superconductors. These methods are quite informative and allow us to obtain many important electron characteristics and temperature relations. Various characteristics of the superconducting compounds Nb{sub 3}Ge, Nb{sub 3}Al, nb{sub 3}Sn and Nb{sub 3}Ga with A15 structure and NbN with B1 structure, having rather high critical temperatures, are experimentally studied.

  12. Superconductivity in Opal-based superconducting nanocomposites

    NASA Astrophysics Data System (ADS)

    Lee, M. K.; Charnaya, E. V.; Chang, L. J.; Kumzerov, Yu. A.; Lin, M. F.

    2015-03-01

    In this study, we investigate superconducting nanocomposites (SCNCs) to elucidate superconductivity in nanostructured type I superconductor. In, Sn and Hg are loaded into opal matrices by high pressure up to 10kbar, in which introducing superconducting metals into templates preserves their own 3D nanostructures. The opal matrices is adopted because it is a well-developed nanoconfinement and widely used in the studies of photonic crystal due to its periodically-superlatticed nanoporous structure. The SCNCs are then measured by Quantum Design MPMS 3 under different external magnetic fields reveal the field dependences of Tc and irreversibility temperature (Tirr). Next, AC susceptibility measurements of SCNCs determine grain coupling, vortex dynamics and field dependence of activation barrier (Ua) as well as Tc. Additionally, the phase diagrams of these SCNCs are analyzed to study superconductivity for a system with similar nanogeometry. Exotic phase diagrams in the opal SCNC studies reveal an enhanced upper critical field (Hc2 (0)) and curvature crossover of upper critical field line. Additionally, according to the field dependence of Ua(H), curvature crossover of the upper critical field line can occur, owing to vortex phase transition.

  13. Process for manufacturing multilayer capacitors

    DOEpatents

    Lauf, Robert J.; Holcombe, Cressie E.; Dykes, Norman L.

    1996-01-01

    The invention is directed to a method of manufacture of multilayer electrical components, especially capacitors, and components made by such a method. High capacitance dielectric materials and low cost metallizations layered with such dielectrics may be fabricated as multilayer electrical components by sintering the metallizations and the dielectrics during the fabrication process by application of microwave radiation.

  14. Process for manufacturing multilayer capacitors

    DOEpatents

    Lauf, R.J.; Holcombe, C.E.; Dykes, N.L.

    1996-01-02

    The invention is directed to a method of manufacture of multilayer electrical components, especially capacitors, and components made by such a method. High capacitance dielectric materials and low cost metallizations layered with such dielectrics may be fabricated as multilayer electrical components by sintering the metallizations and the dielectrics during the fabrication process by application of microwave radiation. 4 figs.

  15. Physical Properties of PC-PMMA Multilayers

    NASA Astrophysics Data System (ADS)

    Rahman, Arifur; Baer, Eric; Chipara, Alin Cristian; Vajtai, Robert; Ajayan, Pullickel M.; Hinthorne, James; Elamin, Ibrahim; Chipara, Mircea; Eric Baer Collaboration; Pullickel Ajayan Collaboration; Mircea Chipara Collaboration

    2015-03-01

    Multilayers of polycarbonate (PC) and polymethylmethacrylate (PMMA) have been obtained by the layer multiplying coextrusion method. Each sample (1024 layers, of equal thickness, with individual thickness between 10 and 200 nm) has been investigated at room temperature by Wide Angle X-Ray Scattering (WAXS) using a Bruker Discovery 8 spectrometer (Cu K α radiation), Raman spectroscopy (Bruker Senterra confocal Raman spectrometer operating at 785 nm), FTIR spectroscopy (Tensor 27 Bruker), and UV-Vis spectroscopy. Further details about the glass transition temperature in these samples have been obtained by Dynamical Mechanical Analysis, DMA, (TA Instruments Q800) at various frequencies in the range 1 to 100 Hz. Isothermal Differential Scanning Calorimetry, DSC, (TA Instruments Q200) was used to investigate the effect of the thickness of the polymeric film on the crystallization processes. Non-isothermal DSC measurements aimed at the identification and location of the main phase transitions (glass, crystallization, and melting) occurring in these multilayers. The effects of confinement on the phase transitions occurring in these multilayers are discussed in detail.

  16. Structures behind superconductivity

    SciTech Connect

    Rotman, D.

    1988-07-01

    The previously reported preparation and structures of superconducting materials are reviewed. The two systems, Y-Ba-Cu-O and La-Cu-O, previously reported with high transition temperatures are discussed in some detail. The new systems introduced in 1987 that were not based on a rare earth but including Bi-Sr-Cu-O are also reviewed. Superconductive materials including thallium rather than bismuth that have been reported but not thoroughly studied are discussed briefly. It is pointed out that many superconducting materials have been prepared, but good documentation of the structures and properties of these materials need much more study.

  17. Tunneling in superconducting structures

    NASA Astrophysics Data System (ADS)

    Shukrinov, Yu. M.

    2010-12-01

    Here we review our results on the breakpoint features in the coupled system of IJJ obtained in the framework of the capacitively coupled Josephson junction model with diffusion current. A correspondence between the features in the current voltage characteristics (CVC) and the character of the charge oscillations in superconducting layers is demonstrated. Investigation of the correlations of superconducting currents in neighboring Josephson junctions and the charge correlations in neighboring superconducting layers reproduces the features in the CVC and gives a powerful method for the analysis of the CVC of coupled Josephson junctions. A new method for determination of the dissipation parameter is suggested.

  18. Superconducting active impedance converter

    DOEpatents

    Ginley, David S.; Hietala, Vincent M.; Martens, Jon S.

    1993-01-01

    A transimpedance amplifier for use with high temperature superconducting, other superconducting, and conventional semiconductor allows for appropriate signal amplification and impedance matching to processing electronics. The amplifier incorporates the superconducting flux flow transistor into a differential amplifier configuration which allows for operation over a wide temperature range, and is characterized by high gain, relatively low noise, and response times less than 200 picoseconds over at least a 10-80 K. temperature range. The invention is particularly useful when a signal derived from either far-IR focal plane detectors or from Josephson junctions is to be processed by higher signal/higher impedance electronics, such as conventional semiconductor technology.

  19. Superconducting active impedance converter

    DOEpatents

    Ginley, D.S.; Hietala, V.M.; Martens, J.S.

    1993-11-16

    A transimpedance amplifier for use with high temperature superconducting, other superconducting, and conventional semiconductors allows for appropriate signal amplification and impedance matching to processing electronics. The amplifier incorporates the superconducting flux flow transistor into a differential amplifier configuration which allows for operation over a wide temperature range, and is characterized by high gain, relatively low noise, and response times less than 200 picoseconds over at least a 10-80 K. temperature range. The invention is particularly useful when a signal derived from either far-IR focal plane detectors or from Josephson junctions is to be processed by higher signal/higher impedance electronics, such as conventional semiconductor technology. 12 figures.

  20. Wrapped Multilayer Insulation

    NASA Technical Reports Server (NTRS)

    Dye, Scott A.

    2015-01-01

    New NASA vehicles, such as Earth Departure Stage (EDS), Orion, landers, and orbiting fuel depots, need improved cryogenic propellant transfer and storage for long-duration missions. Current cryogen feed line multilayer insulation (MLI) performance is 10 times worse per area than tank MLI insulation. During each launch, cryogenic piping loses approximately 150,000 gallons (equivalent to $300,000) in boil-off during transfer, chill down, and ground hold. Quest Product Development Corp., teaming with Ball Aerospace, developed an innovative advanced insulation system, Wrapped MLI (wMLI), to provide improved thermal insulation for cryogenic feed lines. wMLI is high-performance multilayer insulation designed for cryogenic piping. It uses Quest's innovative discrete-spacer technology to control layer spacing/ density and reduce heat leak. The Phase I project successfully designed, built, and tested a wMLI prototype with a measured heat leak 3.6X lower than spiral-wrapped conventional MLI widely used for piping insulation. A wMLI prototype had a heat leak of 7.3 W/m2, or 27 percent of the heat leak of conventional MLI (26.7 W/m2). The Phase II project is further developing wMLI technology with custom, molded polymer spacers and advancing the product toward commercialization via a rigorous testing program, including developing advanced vacuuminsulated pipe for ground support equipment.

  1. Wrapped Multilayer Insulation

    NASA Technical Reports Server (NTRS)

    Dye, Scott A.

    2015-01-01

    New NASA vehicles, such as Earth Departure Stage (EDS), Orion, landers, and orbiting fuel depots, need improved cryogenic propellant transfer and storage for long-duration missions. Current cryogen feed line multilayer insulation (MLI) performance is 10 times worse per area than tank MLI insulation. During each launch, cryogenic piping loses approximately 150,000 gallons (equivalent to $300,000) in boil-off during transfer, chill down, and ground hold. Quest Product Development Corp., teaming with Ball Aerospace, developed an innovative advanced insulation system, Wrapped MLI (wMLI), to provide improved thermal insulation for cryogenic feed lines. wMLI is high-performance multilayer insulation designed for cryogenic piping. It uses Quest's innovative discrete-spacer technology to control layer spacing/ density and reduce heat leak. The Phase I project successfully designed, built, and tested a wMLI prototype with a measured heat leak 3.6X lower than spiral-wrapped conventional MLI widely used for piping insulation. A wMLI prototype had a heat leak of 7.3 W/sq m, or 27 percent of the heat leak of conventional MLI (26.7 W/sq m). The Phase II project is further developing wMLI technology with custom, molded polymer spacers and advancing the product toward commercialization via a rigorous testing program, including developing advanced vacuuminsulated pipe for ground support equipment.

  2. Ultrahard Multilayer Coatings

    SciTech Connect

    Chrzan, D.C.; Dugger, M.; Follstaedt, D.M.; Friedman, Lawrence H.; Friedmann, T.A.; Knapp, J.A.; McCarty, K.F.; Medlin, D.L.; Mirkarimi, P.B.; Missert, N.; Newcomer, P.P.; Sullivan, J.P.; Tallant, D.R.

    1999-05-01

    We have developed a new multilayer a-tC material that is thick stress-free, adherent, low friction, and with hardness and stiffness near that of diamond. The new a-tC material is deposited by J pulsed-laser deposition (PLD) at room temperature, and fully stress-relieved by a short thermal anneal at 600°C. A thick multilayer is built up by repeated deposition and annealing steps. We measured 88 GPa hardness, 1100 GPa Young's modulus, and 0.1 friction coefficient (under high load). Significantly, these results are all well within the range reported for crystalline diamond. In fact, this material, if considered separate from crystalline diamond, is the 2nd hardest material known to man. Stress-free a-tC also has important advantages over thin film diamond; namely, it is smooth, processed at lower temperature, and can be grown on a much broader range of substrates. This breakthrough will enable a host of applications that we are actively pursuing in MEMs, sensors, LIGA, etc.

  3. Fabrication of multi-layered absorption structure for high quantum efficiency photon detectors

    SciTech Connect

    Fujii, Go; Fukuda, Daiji; Numata, Takayuki; Yoshizawa, Akio; Tsuchida, Hidemi; Fujino, Hidetoshi; Ishii, Hiroyuki; Itatani, Taro; Zama, Tatsuya; Inoue, Shuichiro

    2009-12-16

    We report on some efforts to improve a quantum efficiency of titanium-based optical superconducting transition edge sensors using the multi-layered absorption structure for maximizing photon absorption in the Ti layer. Using complex refractive index values of each film measured by a Spectroscopic Ellipsometry, we designed and optimized by a simulation code. An absorption measurement of fabricated structure was in good agreement with the design and was higher than 99% at optimized wavelength of 1550 nm.

  4. Reliability of large superconducting magnets through design

    NASA Astrophysics Data System (ADS)

    Henning, C. D.

    1980-09-01

    As superconducting magnet systems grow larger and become the central component of major systems involving fusion, magnetohydrodynamics, and high energy physics, their reliability must be commensurate with the enormous capital investment in the project. Creative design is the most effective way of ensuring magnet reliability and providing a reasonable limit on the amount of quality control needed. By subjecting the last drawing operation in superconductor manufacture to a stress larger than the magnet design stress, a 100 percent proof test is achieved; cabled conductors offer mechanical redundancy, as do some methods of conductor joining; ground plane insulation should be multilayered to prevent arcs, and interturn and interlayer insulation spaced to be compatible with the self-extinguishing of arcs during quench voltages; electrical leads should be thermally protected; and guard vacuum spaces can be incorporated to control helium leaks.

  5. Hybrid superconducting magnetic suspensions

    SciTech Connect

    Tixador, P.; Hiebel, P.; Brunet, Y.

    1996-07-01

    Superconductors, especially high T{sub c} ones, are the most attractive materials to design stable and fully passive magnetic suspensions which have to control five degrees of freedom. The hybrid superconducting magnetic suspensions present high performances and a simple cooling mode. They consist of a permanent magnet bearing, stabilized by a suitable magnet-superconductor structure. Several designs are given and compared in terms of forces and stiffnesses. The design of the magnet bearing plays an important part. The superconducting magnetic bearing participates less in levitation but must provide a high stabilizing stiffness. This is achieved by the magnet configuration, a good material in term of critical current density and field cooling. A hybrid superconducting suspension for a flywheel is presented. This system consists of a magnet thrust bearing stabilized by superconductors interacting with an alternating polarity magnet structure. First tests and results are reported. Superconducting materials are magnetically melt-textured YBaCuO.

  6. Superconducting thermoelectric generator

    DOEpatents

    Metzger, John D.; El-Genk, Mohamed S.

    1998-01-01

    An apparatus and method for producing electricity from heat. The present invention is a thermoelectric generator that uses materials with substantially no electrical resistance, often called superconductors, to efficiently convert heat into electrical energy without resistive losses. Preferably, an array of superconducting elements is encased within a second material with a high thermal conductivity. The second material is preferably a semiconductor. Alternatively, the superconducting material can be doped on a base semiconducting material, or the superconducting material and the semiconducting material can exist as alternating, interleaved layers of waferlike materials. A temperature gradient imposed across the boundary of the two materials establishes an electrical potential related to the magnitude of the temperature gradient. The superconducting material carries the resulting electrical current at zero resistivity, thereby eliminating resistive losses. The elimination of resistive losses significantly increases the conversion efficiency of the thermoelectric device.

  7. Superconducting thermoelectric generator

    SciTech Connect

    Metzger, J.D.; El-Genk, M.S.

    1998-05-05

    An apparatus and method for producing electricity from heat is disclosed. The present invention is a thermoelectric generator that uses materials with substantially no electrical resistance, often called superconductors, to efficiently convert heat into electrical energy without resistive losses. Preferably, an array of superconducting elements is encased within a second material with a high thermal conductivity. The second material is preferably a semiconductor. Alternatively, the superconducting material can be doped on a base semiconducting material, or the superconducting material and the semiconducting material can exist as alternating, interleaved layers of waferlike materials. A temperature gradient imposed across the boundary of the two materials establishes an electrical potential related to the magnitude of the temperature gradient. The superconducting material carries the resulting electrical current at zero resistivity, thereby eliminating resistive losses. The elimination of resistive losses significantly increases the conversion efficiency of the thermoelectric device. 4 figs.

  8. Superconducting thermoelectric generator

    SciTech Connect

    Metzger, J.D.; El-Genk, M.S.

    1996-01-01

    An apparatus and method for producing electricity from heat. The present invention is a thermoelectric generator that uses materials with substantially no electrical resistance, often called superconductors, to efficiently convert heat into electrical energy without resistive losses. Preferably, an array of superconducting elements is encased within a second material with a high thermal conductivity. The second material is preferably a semiconductor. Alternatively, the superconducting material can be doped on a base semiconducting material, or the superconducting material and the semiconducting material can exist as alternating, interleaved layers of waferlike materials. A temperature gradient imposed across the boundary of the two materials establishes an electrical potential related to the magnitude of the temperature gradient. The superconducting material carries the resulting electrical current at zero resistivity, thereby eliminating resistive losses. The elimination of resistive losses significantly increases the conversion efficiency of the thermoelectric device.

  9. Supertubes and Superconducting Membranes

    SciTech Connect

    Cordero, Ruben; Miguel-Pilar, Zelin

    2007-02-09

    We show the equivalence between configurations that arise from string theory of type IIA, called supertubes, and superconducting membranes at the bosonic level. We find equilibrium and oscillating configurations for a tubular membrane carrying a current along its axis.

  10. High Temperature Superconducting Compounds.

    DTIC Science & Technology

    1999-04-02

    addition to superconducting films, non-superconducting mixed-valence manganite perovskites, which exhibit so-called colossal magnetoresistance were grown...The manganites are unique in that their charge carriers are believed to be almost 100% spin polarized. These materials were combined with the...brought about by the injection of spin polarized carriers from the manganite into the curate. This work may make possible new classes of devices based on

  11. Osseointegration of a hydroxyapatite-coated multilayered mesh stem.

    PubMed

    Kusakabe, Hiroshi; Sakamaki, Toyonori; Nihei, Kotaro; Oyama, Yasuo; Yanagimoto, Shigeru; Ichimiya, Masaru; Kimura, Jun; Toyama, Yoshiaki

    2004-07-01

    A new type of porous coating for hip prostheses called "multilayered mesh" was tested under weight-bearing conditions. The surface of the stem is constructed of titanium mesh produced by etching. The hip stems of hydroxyapatite (HA)-coated multilayered mesh and conventional beads were implanted into canine right hips, and animals were killed 3, 6 and 10 weeks and 6 and 12 months after implantation. Shear strength between the implant and the bone was evaluated by the push-out test. Bone ingrowth was calculated from backscattered electron imaging-scanning electron microscopy (BEI-SEM) images of transverse sections. Toluidine blue stained sections and the BEI-SEM images were evaluated histologically. The break sites of the specimens after the push-out test were evaluated on BEI-SEM images of longitudinal sections. The mean push-out strength of the HA-coated multilayered mesh samples was greater than that of the beads-coated samples every time tested, and the HA-coated multilayered mesh implants had significantly stronger push-out strength at 3 and 6 weeks (p<0.05). The strength of the HA-coated multilayered mesh implants was even greater at 6 and 12 months, whereas the strength of the beads-coated samples decreased. The HA-coated multilayered mesh implants showed significantly higher percentages of bone ingrowth than the beads-coated implants every time tested, except at 6 months (p<0.05). At 6 and 12 months, the bone ingrowth data for the HA-coated multilayered mesh implants increased, whereas it decreased for the beads-coated implants. The new bone formation had reached the bottom of the porous area of the HA-coated multilayered mesh surface by 3 weeks, but not had reached the bottom of the conventional beads surface. At 6 and 12 months, the smaller pores of the bead surface stopped the thickening of trabecular bone, and at 12 months, the break sites were at the bone-implant interface of the bead surface, whereas they were on the bone side of the HA

  12. Making Superconducting Welds between Superconducting Wires

    NASA Technical Reports Server (NTRS)

    Penanen, Konstantin I.; Eom, Byeong Ho

    2008-01-01

    A technique for making superconducting joints between wires made of dissimilar superconducting metals has been devised. The technique is especially suitable for fabrication of superconducting circuits needed to support persistent electric currents in electromagnets in diverse cryogenic applications. Examples of such electromagnets include those in nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) systems and in superconducting quantum interference devices (SQUIDs). Sometimes, it is desirable to fabricate different parts of a persistent-current-supporting superconducting loop from different metals. For example, a sensory coil in a SQUID might be made of Pb, a Pb/Sn alloy, or a Cu wire plated with Pb/Sn, while the connections to the sensory coil might be made via Nb or Nb/Ti wires. Conventional wire-bonding techniques, including resistance spot welding and pressed contact, are not workable because of large differences between the hardnesses and melting temperatures of the different metals. The present technique is not subject to this limitation. The present technique involves the use (1) of a cheap, miniature, easy-to-operate, capacitor-discharging welding apparatus that has an Nb or Nb/Ti tip and operates with a continuous local flow of gaseous helium and (2) preparation of a joint in a special spark-discharge welding geometry. In a typical application, a piece of Nb foil about 25 m thick is rolled to form a tube, into which is inserted a wire that one seeks to weld to the tube (see figure). The tube can be slightly crimped for mechanical stability. Then a spark weld is made by use of the aforementioned apparatus with energy and time settings chosen to melt a small section of the niobium foil. The energy setting corresponds to the setting of a voltage to which the capacitor is charged. In an experiment, the technique was used to weld an Nb foil to a copper wire coated with a Pb/Sn soft solder, which is superconducting. The joint was evaluated as

  13. Superconducting transmission line particle detector

    DOEpatents

    Gray, K.E.

    1988-07-28

    A microvertex particle detector for use in a high energy physic collider including a plurality of parallel superconducting thin film strips separated from a superconducting ground plane by an insulating layer to form a plurality of superconducting waveguides. The microvertex particle detector indicates passage of a charged subatomic particle by measuring a voltage pulse measured across a superconducting waveguide caused by the transition of the superconducting thin film strip from a superconducting to a non- superconducting state in response to the passage of a charged particle. A plurality of superconducting thin film strips in two orthogonal planes plus the slow electromagnetic wave propagating in a superconducting transmission line are used to resolve N/sup 2/ ambiguity of charged particle events. 6 figs.

  14. Superconducting transmission line particle detector

    DOEpatents

    Gray, Kenneth E.

    1989-01-01

    A microvertex particle detector for use in a high energy physic collider including a plurality of parallel superconducting thin film strips separated from a superconducting ground plane by an insulating layer to form a plurality of superconducting waveguides. The microvertex particle detector indicates passage of a charged subatomic particle by measuring a voltage pulse measured across a superconducting waveguide caused by the transition of the superconducting thin film strip from a superconducting to a non-superconducting state in response to the passage of a charged particle. A plurality of superconducting thin film strips in two orthogonal planes plus the slow electromagnetic wave propogating in a superconducting transmission line are used to resolve N.sup.2 ambiguity of charged particle events.

  15. Apparatus for characterizing conductivity of superconducting materials

    DOEpatents

    Doss, James D.

    1993-01-01

    Apparatus and method for noncontact, radio-frequency shielding current characterization of materials. Self- or mutual inductance changes in one or more inductive elements, respectively, occur when materials capable of supporting shielding currents are placed in proximity thereto, or undergo change in resistivity while in place. Such changes can be observed by incorporating the inductor(s) in a resonant circuit and determining the frequency of oscillation or by measuring the voltage induced on a coupled inductive element. The present invention is useful for determining the critical temperature and superconducting transition width for superconducting samples.

  16. Apparatus for characterizing conductivity of superconducting materials

    DOEpatents

    Doss, J.D.

    1993-12-07

    Apparatus and method for noncontact, radio-frequency shielding current characterization of materials. Self- or mutual inductance changes in one or more inductive elements, respectively, occur when materials capable of supporting shielding currents are placed in proximity thereto, or undergo change in resistivity while in place. Such changes can be observed by incorporating the inductor(s) in a resonant circuit and determining the frequency of oscillation or by measuring the voltage induced on a coupled inductive element. The present invention is useful for determining the critical temperature and superconducting transition width for superconducting samples. 10 figures.

  17. Midwest Superconductivity Consortium: 1994 Progress report

    SciTech Connect

    Not Available

    1995-01-01

    The mission of the Midwest Superconductivity Consortium, MISCON, is to advance the science and understanding of high {Tc} superconductivity. During the past year, 27 projects produced over 123 talks and 139 publications. Group activities and interactions involved 2 MISCON group meetings (held in August and January); with the second MISCON Workshop held in August; 13 external speakers; 79 collaborations (with universities, industry, Federal laboratories, and foreign research centers); and 48 exchanges of samples and/or measurements. Research achievements this past year focused on understanding the effects of processing phenomena on structure-property interrelationships and the fundamental nature of transport properties in high-temperature superconductors.

  18. Superconductive radiofrequency window assembly

    DOEpatents

    Phillips, Harry Lawrence; Elliott, Thomas S.

    1998-01-01

    The present invention is a superconducting radiofrequency window assembly for use in an electron beam accelerator. The srf window assembly (20) has a superconducting metal-ceramic design. The srf window assembly (20) comprises a superconducting frame (30), a ceramic plate (40) having a superconducting metallized area, and a superconducting eyelet (50) for sealing plate (40) into frame (30). The plate (40) is brazed to eyelet (50) which is then electron beam welded to frame (30). A method for providing a ceramic object mounted in a metal member to withstand cryogenic temperatures is also provided. The method involves a new metallization process for coating a selected area of a ceramic object with a thin film of a superconducting material. Finally, a method for assembling an electron beam accelerator cavity utilizing the srf window assembly is provided. The procedure is carried out within an ultra clean room to minimize exposure to particulates which adversely affect the performance of the cavity within the electron beam accelerator.

  19. Superconducting radiofrequency window assembly

    DOEpatents

    Phillips, Harry L.; Elliott, Thomas S.

    1997-01-01

    The present invention is a superconducting radiofrequency window assembly for use in an electron beam accelerator. The srf window assembly (20) has a superconducting metal-ceramic design. The srf window assembly (20) comprises a superconducting frame (30), a ceramic plate (40) having a superconducting metallized area, and a superconducting eyelet (50) for sealing plate (40) into frame (30). The plate (40) is brazed to eyelet (50) which is then electron beam welded to frame (30). A method for providing a ceramic object mounted in a metal member to withstand cryogenic temperatures is also provided. The method involves a new metallization process for coating a selected area of a ceramic object with a thin film of a superconducting material. Finally, a method for assembling an electron beam accelerator cavity utilizing the srf window assembly is provided. The procedure is carried out within an ultra clean room to minimize exposure to particulates which adversely affect the performance of the cavity within the electron beam accelerator.

  20. High temperature interfacial superconductivity

    SciTech Connect

    Bozovic, Ivan; Logvenov, Gennady; Gozar, Adrian Mihai

    2012-06-19

    High-temperature superconductivity confined to nanometer-scale interfaces has been a long standing goal because of potential applications in electronic devices. The spontaneous formation of a superconducting interface in bilayers consisting of an insulator (La.sub.2CuO.sub.4) and a metal (La.sub.1-xSr.sub.xCuO.sub.4), neither of which is superconducting per se, is described. Depending upon the layering sequence of the bilayers, T.sub.c may be either .about.15 K or .about.30 K. This highly robust phenomenon is confined to within 2-3 nm around the interface. After exposing the bilayer to ozone, T.sub.c exceeds 50 K and this enhanced superconductivity is also shown to originate from a 1 to 2 unit cell thick interfacial layer. The results demonstrate that engineering artificial heterostructures provides a novel, unconventional way to fabricate stable, quasi two-dimensional high T.sub.c phases and to significantly enhance superconducting properties in other superconductors. The superconducting interface may be implemented, for example, in SIS tunnel junctions or a SuFET.

  1. Ultrasonic NDE of Multilayered Structures

    SciTech Connect

    Quarry, M J; Fisher, K A; Lehman, S K

    2005-02-14

    This project developed ultrasonic nondestructive evaluation techniques based on guided and bulk waves in multilayered structures using arrays. First, a guided wave technique was developed by preferentially exciting dominant modes with energy in the layer of interest via an ultrasonic array. Second, a bulk wave technique uses Fermat's principle of least time as well as wave-based properties to reconstruct array data and image the multilayered structure. The guided wave technique enables the inspection of inaccessible areas of a multilayered structure without disassembling it. Guided waves propagate using the multilayer as a waveguide into the inaccessible areas from an accessible position. Inspecting multi-layered structures with a guided wave relies on exciting modes with sufficient energy in the layer of interest. Multilayered structures are modeled to determine the possible modes and their distribution of energy across the thickness. Suitable modes were determined and excited by designing arrays with the proper element spacing and frequency. Bulk wave imaging algorithms were developed to overcome the difficulties of multiple reflections and refractions at interfaces. Reconstruction algorithms were developed to detect and localize flaws. A bent-ray algorithm incorporates Fermat's principle to correct time delays in the ultrasonic data that result from the difference in wave speeds in each layer and refractions at the interfaces. A planar wave-based algorithm was developed using the Green function for the multilayer structure to enhance focusing on reception for improved imaging.

  2. Multilayer Mg: Stainless Steel Sheets, Microstructure, and Mechanical Properties

    NASA Astrophysics Data System (ADS)

    Inoue, Junya; Sadeghi, Alireza; Kyokuta, Nobuhiko; Ohmori, Toshinori; Koseki, Toshihiko

    2017-02-01

    Different multilayer Mg AZ31 and SS304L steel sheet combinations were prepared with different volume fractions of Mg. Isolated stress-strain curves of the Mg layers showed significant improvements in the strength and elongation of multilayer samples. Results indicated that in the most extreme situation with the lowest Mg volume fraction (V f = 0.39), the ultimate strength was increased by 25 pct to 370 MPa and the elongation was improved by 70 pct to 0.34. Investigation of the fracture surface showed that failure occurs by the coalescence of cracks close to the interface region. The improved strength of the multilayer samples was due to the combined effect of surface crack prevention by the steel layer and the higher work-hardening rate caused by the possible increased activity of non-basal systems. It is suggested that the stronger work-hardening behavior and the enhanced activity of non-basal systems in the multilayer samples were due to the formation of new stress components in the transverse direction. The larger the volume fraction of steel in the multilayer, the longer the distance remaining unstrained before the UTS.

  3. Magnetic multilayers on nanospheres.

    PubMed

    Albrecht, Manfred; Hu, Guohan; Guhr, Ildico L; Ulbrich, Till C; Boneberg, Johannes; Leiderer, Paul; Schatz, Günter

    2005-03-01

    Thin-film technology is widely implemented in numerous applications. Although flat substrates are commonly used, we report on the advantages of using curved surfaces as a substrate. The curvature induces a lateral film-thickness variation that allows alteration of the properties of the deposited material. Based on this concept, a variety of implementations in materials science can be expected. As an example, a topographic pattern formed of spherical nanoparticles is combined with magnetic multilayer film deposition. Here we show that this combination leads to a new class of magnetic material with a unique combination of remarkable properties: The so-formed nanostructures are monodisperse, magnetically isolated, single-domain, and reveal a uniform magnetic anisotropy with an unexpected switching behaviour induced by their spherical shape. Furthermore, changing the deposition angle with respect to the particle ensemble allows tailoring of the orientation of the magnetic anisotropy, which results in tilted nanostructure material.

  4. Multilayer optical dielectric coating

    DOEpatents

    Emmett, John L.

    1990-01-01

    A highly damage resistant, multilayer, optical reflective coating includes alternating layers of doped and undoped dielectric material. The doping levels are low enough that there are no distinct interfaces between the doped and undoped layers so that the coating has properties nearly identical to the undoped material. The coating is fabricated at high temperature with plasma-assisted chemical vapor deposition techniques to eliminate defects, reduce energy-absorption sites, and maintain proper chemical stoichiometry. A number of differently-doped layer pairs, each layer having a thickness equal to one-quarter of a predetermined wavelength in the material are combined to form a narrowband reflective coating for a predetermined wavelength. Broadband reflectors are made by using a number of narrowband reflectors, each covering a portion of the broadband.

  5. Superconducting mirror for laser gyroscope

    SciTech Connect

    Wang, X.

    1991-05-14

    This paper describes an apparatus for reflecting a light beam. It comprises: a mirror assembly comprising a substrate and a superconductive mirror formed on such substrate, wherein: the substrate is optically transparent to the light beam and has a thickness of from about 0.5 to about 1.0 millimeter, and the superconductive mirror has a thickness of from about 0.5 to about 1.0 microns; means for cooling the superconductive mirror; means for measuring the temperature of the superconductive mirror; means for determining the reflectivity of the superconductive mirror; and means for varying the reflectivity of the superconductive mirror.

  6. Deposition of superconducting thin films by laser ablation processing

    SciTech Connect

    Kim, B.F.; Bohandy, J.; Moorjani, K.; Adrian, F.J.

    1988-02-25

    Superconducting thin films, approximately 1 ..mu..m thick and 1 cm/sup 2/ in area, have been deposited on fused silica by ablation of the bulk material, YBa/sub 2/Cu/sub 3/O/sub 7-y/, using a pulsed excimer laser. The presence of superconductivity in as-deposited films was established by a novel variation of the technique of microwave absorption, in which the superconducting transition appears as a peak in the temperature dependence of the microwave response. The method is sensitive enough to allow detection of superconductivity in small (approx.0.1 mg) samples and is capable of resolving multiple superconducting phases with slight differences in T/sub c/. As-deposited films have essentially the same value of T/sub c/ (94K) as the bulk material.

  7. Integrated Multilayer Insulation

    NASA Technical Reports Server (NTRS)

    Dye, Scott

    2009-01-01

    Integrated multilayer insulation (IMLI) is being developed as an improved alternative to conventional multilayer insulation (MLI), which is more than 50 years old. A typical conventional MLI blanket comprises between 10 and 120 metallized polymer films separated by polyester nets. MLI is the best thermal- insulation material for use in a vacuum, and is the insulation material of choice for spacecraft and cryogenic systems. However, conventional MLI has several disadvantages: It is difficult or impossible to maintain the desired value of gap distance between the film layers (and consequently, it is difficult or impossible to ensure consistent performance), and fabrication and installation are labor-intensive and difficult. The development of IMLI is intended to overcome these disadvantages to some extent and to offer some additional advantages over conventional MLI. The main difference between IMLI and conventional MLI lies in the method of maintaining the gaps between the film layers. In IMLI, the film layers are separated by what its developers call a micro-molded discrete matrix, which can be loosely characterized as consisting of arrays of highly engineered, small, lightweight, polymer (typically, thermoplastic) frames attached to, and placed between, the film layers. The term "micro-molded" refers to both the smallness of the frames and the fact that they are fabricated in a process that forms precise small features, described below, that are essential to attainment of the desired properties. The term "discrete" refers to the nature of the matrix as consisting of separate frames, in contradistinction to a unitary frame spanning entire volume of an insulation blanket.

  8. Bulk Superconductivity and Disorder in Single Crystals of LaFePO

    SciTech Connect

    Analytis, James G.; Chu, Jiun-Haw; Erickson, Ann S.; Kucharczyk, Chris; Serafin, Alessandro; Carrington, Antony; Cox, Catherine; Kauzlarich, Susan M.; Hope, Hakon; /UC, Davis. Dept. Chem.

    2010-02-15

    We have studied the intrinsic normal and superconducting properties of the oxypnictide LaFePO. These samples exhibit bulk superconductivity and the evidence suggests that stoichiometric LaFePO is indeed superconducting, in contrast to other reports. We find that superconductivity is independent of the interplane residual resistivity {rho}{sub 0} and discuss the implications of this on the nature of the superconducting order parameter. Finally we find that, unlike T{sub c}, other properties in single-crystal LaFePO including the resistivity and magnetoresistance, can be very sensitive to disorder.

  9. Thin-film multilayer interconnect technology for YBa2Cu3O7 - x

    NASA Astrophysics Data System (ADS)

    Wellstood, F. C.; Kingston, J. J.; Clarke, John

    1994-01-01

    The construction of microelectronic circuits from high-transition-temperature (Tc) superconductors requires techniques for producing thin-film wires, insulating crossovers, and vias (window contacts) between wires. Together, these three components form a superconducting interconnect technology. The challenges encountered in developing such a technology for high-Tc superconductors involve factors associated with the materials, the circuits and the fabrication techniques. The use of pulsed laser deposition in conjunction with shadow mask patterning, photolithographic pattern definition, acid etching, ion-beam etching, and surface cleaning to produce multilayer interconnects from YBa2Cu3O7-x (YBCO) is discussed. These processes have been used to construct a variety of passive high-temperature superconducting components and circuits, including crossovers, window contacts, multiturn coils, and flux transformers. Integrated magnetometers incorporating superconducting quantum interference devices, multichip modules with semiconductor die bonded to YBCO interconnect structures, and analog-to-digital converters have also been successfully demonstrated.

  10. Superconductivity in Al-substituted Ba8Si46 clathrates

    NASA Astrophysics Data System (ADS)

    Li, Yang; Garcia, Jose; Chen, Ning; Liu, Lihua; Li, Feng; Wei, Yuping; Bi, Shanli; Cao, Guohui; Feng, Z. S.

    2013-05-01

    There is a great deal of interest vested in the superconductivity of Si clathrate compounds with sp3 network, in which the structure is dominated by strong covalent bonds among silicon atoms, rather than the metallic bonding that is more typical of traditional superconductors. A joint experimental and theoretical investigation of superconductivity in Al-substituted type-I silicon clathrates is reported. Samples of the general formula Ba8Si46-xAlx, with different values of x were prepared. With an increase in the Al composition, the superconducting transition temperature TC was observed to decrease systematically. The resistivity measurement revealed that Ba8Si42Al4 is superconductive with transition temperature at TC = 5.5 K. The magnetic measurements showed that the bulk superconducting Ba8Si42Al4 is a type II superconductor. For x = 6 sample Ba8Si40Al6, the superconducting transition was observed down to TC = 4.7 K which pointed to a strong suppression of superconductivity with increasing Al content as compared with TC = 8 K for Ba8Si46. Suppression of superconductivity can be attributed primarily to a decrease in the density of states at the Fermi level, caused by reduced integrity of the sp3 hybridized networks as well as the lowering of carrier concentration. These results corroborated by first-principles calculations showed that Al substitution results in a large decrease of the electronic density of states at the Fermi level, which also explains the decreased superconducting critical temperature within the BCS framework. The work provided a comprehensive understanding of the doping effect on superconductivity of clathrates.

  11. Superconducting nanostructured materials.

    SciTech Connect

    Metlushko, V.

    1998-07-13

    Within the last year it has been realized that the remarkable properties of superconducting thin films containing a periodic array of defects (such as sub-micron sized holes) offer a new route for developing a novel superconducting materials based on precise control of microstructure by modern photolithography. A superconductor is a material which, when cooled below a certain temperature, loses all resistance to electricity. This means that superconducting materials can carry large electrical currents without any energy loss--but there are limits to how much current can flow before superconductivity is destroyed. The current at which superconductivity breaks down is called the critical current. The value of the critical current is determined by the balance of Lorentz forces and pinning forces acting on the flux lines in the superconductor. Lorentz forces proportional to the current flow tend to drive the flux lines into motion, which dissipates energy and destroys zero resistance. Pinning forces created by isolated defects in the microstructure oppose flux line motion and increase the critical current. Many kinds of artificial pinning centers have been proposed and developed to increase critical current performance, ranging from dispersal of small non-superconducting second phases to creation of defects by proton, neutron or heavy ion irradiation. In all of these methods, the pinning centers are randomly distributed over the superconducting material, causing them to operate well below their maximum efficiency. We are overcome this drawback by creating pinning centers in aperiodic lattice (see Fig 1) so that each pin site interacts strongly with only one or a few flux lines.

  12. Tuning superconductivity by carrier injection

    NASA Astrophysics Data System (ADS)

    Müller, Paul

    2011-03-01

    All high-Tc cuprates are stacking sequences of Cu O2 layers and charge reservoir layers consisting of metal oxides. Upon doping the Cu O2 layers, antiferromagnetic order is destroyed and metallic conductivity is established. Usually doping is achieved by a non-stoichiometric composition of the charge reservoir layer. However, we already have shown that we can change the carrier concentration of Bi 2 Sr 2 CaCu 2 O8 + δ single crystals by current injection along the c- axis. Critical temperature, c-axis resistivity and critical current of intrinsic Josephson junctions can be tuned in a large range from underdoping to extreme overdoping. This effect is persistent up to annealing temperatures of approximately 270 K. Using current injection at higher bias, we were able to reduce the carrier concentration again. We investigated in detail the superconducting properties by performing macroscopic quantum tunneling experiments of intrinsic Josephson junctions. The experiments have been carried out repeatedly on samples, whose properties were changed only by current injection. An exponential increase of the critical current density with hole concentration was observed. At the same time, the capacitance of intrinsic Josephson junctions increased significantly. Finally, only by current injection, we were able to convert into the superconducting state a nonsuperconducting, oxygen depleted sample. This work was done in collaboration with Y. Koval, X.Y. Jin, S. Probst, Y. Simsek, C. Steiner (Universität Erlangen), H. B. Wang (NIMS, Tsukuba), and G. Behr, B. Büchner (IFW Dresden).

  13. Multilayered Magnetic Gelatin Membrane Scaffolds

    PubMed Central

    Samal, Sangram K.; Goranov, Vitaly; Dash, Mamoni; Russo, Alessandro; Shelyakova, Tatiana; Graziosi, Patrizio; Lungaro, Lisa; Riminucci, Alberto; Uhlarz, Marc; Bañobre-López, Manuel; Rivas, Jose; Herrmannsdörfer, Thomas; Rajadas, Jayakumar; De Smedt, Stefaan; Braeckmans, Kevin; Kaplan, David L.; Dediu, V. Alek

    2016-01-01

    A versatile approach for the design and fabrication of multilayer magnetic scaffolds with tunable magnetic gradients is described. Multilayer magnetic gelatin membrane scaffolds with intrinsic magnetic gradients were designed to encapsulate magnetized bioagents under an externally applied magnetic field for use in magnetic-field-assisted tissue engineering. The temperature of the individual membranes increased up to 43.7 °C under an applied oscillating magnetic field for 70 s by magnetic hyperthermia, enabling the possibility of inducing a thermal gradient inside the final 3D multilayer magnetic scaffolds. On the basis of finite element method simulations, magnetic gelatin membranes with different concentrations of magnetic nanoparticles were assembled into 3D multilayered scaffolds. A magnetic-gradient-controlled distribution of magnetically labeled stem cells was demonstrated in vitro. This magnetic biomaterial–magnetic cell strategy can be expanded to a number of different magnetic biomaterials for various tissue engineering applications. PMID:26451743

  14. Multilayer thermal barrier coating systems

    DOEpatents

    Vance, Steven J.; Goedjen, John G.; Sabol, Stephen M.; Sloan, Kelly M.

    2000-01-01

    The present invention generally describes multilayer thermal barrier coating systems and methods of making the multilayer thermal barrier coating systems. The thermal barrier coating systems comprise a first ceramic layer, a second ceramic layer, a thermally grown oxide layer, a metallic bond coating layer and a substrate. The thermal barrier coating systems have improved high temperature thermal and chemical stability for use in gas turbine applications.

  15. Cryogenic Systems and Superconductive Power

    DTIC Science & Technology

    subsystem suitable for providing reliable long-lived cryogenic refrigeration for a superconductive ship propulsion system; and, Provide a sound...technical basis for subsequent applications of superconductive power in the area of ship propulsion .

  16. Synchrotron x-ray study of multilayers in Laue geometry

    SciTech Connect

    Kang, H C; Stephenson, G B; Liu, C; Conley, R; Macrander, A T; Maser, J; Bajt, S; Chapman, H N

    2004-07-21

    Zone plates with depth to zone-width ratios as large as 100 are needed for focusing of hard x-rays. Such high aspect ratios are challenging to produce by lithography. We are investigating the fabrication of high-aspect-ratio linear zone plates by multilayer deposition followed by sectioning. As an initial step in this work, we present a synchrotron x-ray study of constant-period multilayers diffracting in Laue (transmission) geometry. Data are presented from two samples: a 200 period W/Si multilayer with d-spacing of 29 nm, and a 2020 period Mo/Si multilayer with d-spacing of 7 nm. By cutting and polishing we have successfully produced thin cross sections with section depths ranging from 2 to 12 {micro}m. Transverse scattering profiles (rocking curves) across the Bragg reflection exhibit well-defined interference fringes originating from the depth of the sample, in agreement with dynamical diffraction theory for a multilayer in Laue geometry.

  17. Superconductivity in diamond.

    PubMed

    Ekimov, E A; Sidorov, V A; Bauer, E D; Mel'nik, N N; Curro, N J; Thompson, J D; Stishov, S M

    2004-04-01

    Diamond is an electrical insulator well known for its exceptional hardness. It also conducts heat even more effectively than copper, and can withstand very high electric fields. With these physical properties, diamond is attractive for electronic applications, particularly when charge carriers are introduced (by chemical doping) into the system. Boron has one less electron than carbon and, because of its small atomic radius, boron is relatively easily incorporated into diamond; as boron acts as a charge acceptor, the resulting diamond is effectively hole-doped. Here we report the discovery of superconductivity in boron-doped diamond synthesized at high pressure (nearly 100,000 atmospheres) and temperature (2,500-2,800 K). Electrical resistivity, magnetic susceptibility, specific heat and field-dependent resistance measurements show that boron-doped diamond is a bulk, type-II superconductor below the superconducting transition temperature T(c) approximately 4 K; superconductivity survives in a magnetic field up to Hc2(0) > or = 3.5 T. The discovery of superconductivity in diamond-structured carbon suggests that Si and Ge, which also form in the diamond structure, may similarly exhibit superconductivity under the appropriate conditions.

  18. Artificial multilayers and nanomagnetic materials

    PubMed Central

    SHINJO, Teruya

    2013-01-01

    The author has been actively engaged in research on nanomagnetic materials for about 50 years. Nanomagnetic materials are comprised of ferromagnetic systems for which the size and shape are controlled on a nanometer scale. Typical examples are ultrafine particles, ultrathin films, multilayered films and nano-patterned films. In this article, the following four areas of the author’s studies are described. (1) Mössbauer spectroscopic studies of nanomagnetic materials and interface magnetism. (2) Preparation and characterization of metallic multilayers with artificial superstructures. (3) Giant magnetoresistance (GMR) effect in magnetic multilayers. (4) Novel properties of nanostructured ferromagnetic thin films (dots and wires). A subject of particular interest in the author’s research was the artificially prepared multilayers consisting of metallic elements. The motivation to initiate the multilayer investigation is described and the physical properties observed in the artificial multilayers are introduced. The author’s research was initially in the field of pure physical science and gradually extended into applied science. His achievements are highly regarded not only from the fundamental point of view but also from the technological viewpoint. PMID:23391605

  19. Interface high-temperature superconductivity

    NASA Astrophysics Data System (ADS)

    Wang, Lili; Ma, Xucun; Xue, Qi-Kun

    2016-12-01

    Cuprate high-temperature superconductors consist of two quasi-two-dimensional (2D) substructures: CuO2 superconducting layers and charge reservoir layers. The superconductivity is realized by charge transfer from the charge reservoir layers into the superconducting layers without chemical dopants and defects being introduced into the latter, similar to modulation-doping in the semiconductor superlattices of AlGaAs/GaAs. Inspired by this scheme, we have been searching for high-temperature superconductivity in ultra-thin films of superconductors epitaxially grown on semiconductor/oxide substrates since 2008. We have observed interface-enhanced superconductivity in both conventional and unconventional superconducting films, including single atomic layer films of Pb and In on Si substrates and single unit cell (UC) films of FeSe on SrTiO3 (STO) substrates. The discovery of high-temperature superconductivity with a superconducting gap of ∼20 meV in 1UC-FeSe/STO has stimulated tremendous interest in the superconductivity community, for it opens a new avenue for both raising superconducting transition temperature and understanding the pairing mechanism of unconventional high-temperature superconductivity. Here, we review mainly the experimental progress on interface-enhanced superconductivity in the three systems mentioned above with emphasis on 1UC-FeSe/STO, studied by scanning tunneling microscopy/spectroscopy, angle-resolved photoemission spectroscopy and transport experiments. We discuss the roles of interfaces and a possible pairing mechanism inferred from these studies.

  20. Superconducting tensor gravity gradiometer

    NASA Technical Reports Server (NTRS)

    Paik, H. J.

    1981-01-01

    The employment of superconductivity and other material properties at cryogenic temperatures to fabricate sensitive, low-drift, gravity gradiometer is described. The device yields a reduction of noise of four orders of magnitude over room temperature gradiometers, and direct summation and subtraction of signals from accelerometers in varying orientations are possible with superconducting circuitry. Additional circuits permit determination of the linear and angular acceleration vectors independent of the measurement of the gravity gradient tensor. A dewar flask capable of maintaining helium in a liquid state for a year's duration is under development by NASA, and a superconducting tensor gravity gradiometer for the NASA Geodynamics Program is intended for a LEO polar trajectory to measure the harmonic expansion coefficients of the earth's gravity field up to order 300.

  1. Nonlinear terahertz superconducting plasmonics

    NASA Astrophysics Data System (ADS)

    Wu, Jingbo; Zhang, Caihong; Liang, Lanju; Jin, Biaobing; Kawayama, Iwao; Murakami, Hironaru; Kang, Lin; Xu, Weiwei; Wang, Huabing; Chen, Jian; Tonouchi, Masayoshi; Wu, Peiheng

    2014-10-01

    Nonlinear terahertz (THz) transmission through subwavelength hole array in superconducting niobium nitride (NbN) film is experimentally investigated using intense THz pulses. The good agreement between the measurement and numerical simulations indicates that the field strength dependent transmission mainly arises from the nonlinear properties of the superconducting film. Under weak THz pulses, the transmission peak can be tuned over a frequency range of 145 GHz which is attributed to the high kinetic inductance of 50 nm-thick NbN film. Utilizing the THz pump-THz probe spectroscopy, we study the dynamic process of transmission spectra and demonstrate that the transition time of such superconducting plasmonic device is within 5 ps.

  2. Multilayer graphene rubber nanocomposites

    NASA Astrophysics Data System (ADS)

    Schartel, Bernhard; Frasca, Daniele; Schulze, Dietmar; Wachtendorf, Volker; Krafft, Bernd; Morys, Michael; Böhning, Martin; Rybak, Thomas

    2016-05-01

    Multilayer Graphene (MLG), a nanoparticle with a specific surface of BET = 250 m2/g and thus made of only approximately 10 graphene sheets, is proposed as a nanofiller for rubbers. When homogenously dispersed, it works at low loadings enabling the replacement of carbon black (CB), increase in efficiency, or reduction in filler concentration. Actually the appropriate preparation yielded nanocomposites in which just 3 phr are sufficient to significantly improve the rheological, curing and mechanical properties of different rubbers, as shown for Chlorine-Isobutylene-Isoprene Rubber (CIIR), Nitrile-Butadiene Rubber (NBR), Natural Rubber (NR), and Styrene-Butadiene Rubber (SBR). A mere 3 phr of MLG tripled the Young's modulus of CIIR, an effect equivalent to 20 phr of carbon black. Similar equivalents are observed for MLG/CB mixtures. MLG reduces gas permeability, increases thermal and electrical conductivities, and retards fire behavior. The later shown by the reduction in heat release rate in the cone calorimeter. The higher the nanofiller concentration is (3 phr, 5 phr, and 10 phr was investigated), the greater the improvement in the properties of the nanocomposites. Moreover, the MLG nanocomposites improve stability of mechanical properties against weathering. An increase in UV-absorption as well as a pronounced radical scavenging are proposed and were proved experimentally. To sum up, MLG is interesting as a multifunctional nanofiller and seems to be quite ready for rubber development.

  3. Superconducting magnetic quadrupole

    SciTech Connect

    Kim, J.W.; Shepard, K.W.; Nolen, J.A.

    1995-08-01

    A design was developed for a 350 T/m, 2.6-cm clear aperture superconducting quadrupole focussing element for use in a very low q/m superconducting linac as discussed below. The quadrupole incorporates holmium pole tips, and a rectangular-section winding using standard commercially-available Nb-Ti wire. The magnet was modeled numerically using both 2D and 3D codes, as a basis for numerical ray tracing using the quadrupole as a linac element. Components for a prototype singlet are being procured during FY 1995.

  4. Technology of RF superconductivity

    SciTech Connect

    1995-08-01

    This work has several parts, two of which are collaborative development projects with the majority of the work being performed at Argonne. The first is the development of a superconducting RFQ structure in collaboration with AccSys Technology Inc. of Pleasanton, California, funded as a Phase II SBIR grant. Another is a collaborative project with the Nuclear Science Centre, New Delhi, India (who are funding the work) to develop new superconducting ion accelerating structures. Other initiatives are developing various aspects of the technology required to utilize ATLAS as a secondary beam linac for radioactive beams.

  5. Superconducting Metastable Compounds.

    PubMed

    Luo, H L; Merriam, M F; Hamilton, D C

    1964-08-07

    A number of metastable phases, germanides and tellurides of gold and silver, have been prepared, analyzed by x-ray diffraction, and investigated for superconductivity. The new superconductors and their transition temperatures are AgTe(3) (2.6 degrees K), Ag(4)Ge (0.85 degrees K), Au(3)Te(5) (1.62 degrees K), and Au(1-x)Ge(x) (0.99 degrees K-1.63 degrees K) where (0.27 superconduct above 0.32 degrees K.

  6. Ceramic superconducting components

    NASA Technical Reports Server (NTRS)

    Haertling, G. H.

    1991-01-01

    An approach to the application of high-Tc ceramic superconductors to practical circuit elements was developed and demonstrated. This method, known as the rigid conductor process (RCP), involves the mounting of a preformed, sintered, and tested superconductor material onto an appropriate, rigid substrate with an epoxy adhesive which also serves to encapsulate the element from the ambient environment. Circuit elements such as straight conductors, coils and connectors were fabricated from YBa2Cu3O(7-x) superconducting material. Performance results are included for a low-noise low-thermal-conductivity superconducting grounding link for NASA.

  7. Onset of superconductivity in sodium and potassium intercalated molybdenum disulphide

    NASA Technical Reports Server (NTRS)

    Somoano, R. B.; Rembaum, A.

    1971-01-01

    Molybdenum disulfide in the form of natural crystals or powder has been intercalated at -65 to -70 C with sodium and potassium using the liquid ammonia technique. All intercalated samples were found to show a superconducting transition. A plot of the percent of diamagnetic throw versus temperature indicates the possible existence of two phases in the potassium intercalated molybdenum disulfide. The onset of superconductivity in potassium and sodium intercalated molybdenite powder was found to be approximately 6.2 and approximately 4.5 K, respectively. The observed superconductivity is believed to be due to an increase in electron density as a result of intercalation.

  8. Synthesis of nanoscale superconducting YBCO by a novel technique

    NASA Astrophysics Data System (ADS)

    Xu, X. L.; Guo, J. D.; Wang, Y. Z.; Sozzi, A.

    2002-06-01

    A novel technique using citrate pyrolysis was developed to prepare nanoscale superconducting oxide materials. This paper describes the details on synthesizing nanocrystalline YBCO with a Tc of ∼80 K using this method. The morphology and structure of the nanoscale products were characterized by powder X-ray diffraction and scanning electron microscopy. The obtained YBCO grains have a mean particle size of 40-60 nm (for unannealed samples) and 100-150 nm (for the annealed products). The crystalline size was only ∼20 nm. Currently there are attempts at using such fine powder to fabricate longer superconducting tapes, which should induce a technical revolution in the production of superconducting tapes.

  9. Magnetic and Superconducting Materials at High Pressures

    SciTech Connect

    Struzhkin, Viktor V.

    2015-03-24

    transitions from magnetic to nonmagnetic phases in a broad pressure-temperature range; using X-ray methods including the newly developed RIXS high-pressure technique to explore pressure-tuned electronic excitations in strongly correlated 3d-materials; and advancing transport and magnetic techniques for measurements on small samples at very high pressures in a wide temperature range, with the application of focused ion beam technology and photolithography tailored to the design of microcircuits down to a nanoscale size, thus expanding the horizon in the search for novel physical phenomena at ultrahigh pressures. Apply new optical magnetic sensing techniques with NV- centers in diamond to detect superconductivity and magnetic transitions with unprecedented spatial resolution.

  10. Switching device for the superconducting phase transition measurements of thin W films using a single superconducting quantum interference device

    NASA Astrophysics Data System (ADS)

    Sáfrán, G.; Loidl, M.; Meier, O.; Angloher, G.; Pröbst, F.; Seidel, W.

    1999-06-01

    A simple superconducting switch has been developed for the measurements of the low temperature superconducting phase transitions of several thin W samples connected simultaneously to a single superconducting quantum interference device. The switch, based on a Ti thin film resistor, can be set to normal or to superconducting within the cryostat by adjusting its temperature above or below the transition temperature by means of a thin film heater. The experimental setup, circuit and device properties, are discussed in detail. As an example of its application the superconducting phase transitions of two thin W samples on sapphire connected in series were measured subsequently as a function of temperature by applying two switches connected parallel to the samples. The switches exhibited a resistance of 67 Ω-1 kΩ at 4 K depending on the thickness and geometry of the Ti film and on the substrate material. The deviation from the real electrical resistance value of the samples caused by the finite resistance of the switches was found to be a maximum of 6×10-6 Ω. This, compared to the resistances to be measured (about 2×10-2 Ω), we consider negligible. The application of several switches within a cryostat can multiply the number of specimens measured in the same cooling cycle, enabling a more efficient characterization of the cryogenic properties of superconducting specimens.

  11. Non-uniform transition conductivity of superconducting ceramic

    NASA Technical Reports Server (NTRS)

    Generazio, Edward R.; Roth, Don J.; Hepp, Aloysius F.

    1989-01-01

    The effects of microstructural variations on the superconducting properties of SmBa2Cu3Ox are investigated. A scanning eddy current probe revealed the onset and growth of a normal conducting region. Resistance versus temperature measurements taken at different regions of the sample support the concept of a physically mixed state system. Regional variations in porosity and grain size distributions affect the observed superconducting transition.

  12. Full spin switch effect for the superconducting current in a superconductor/ferromagnet thin film heterostructure

    NASA Astrophysics Data System (ADS)

    Leksin, P. V.; Garif'yanov, N. N.; Garifullin, I. A.; Schumann, J.; Vinzelberg, H.; Kataev, V.; Klingeler, R.; Schmidt, O. G.; Büchner, B.

    2010-09-01

    Using the spin switch design F1/F2/S theoretically proposed by Oh et al., [Appl. Phys. Lett. 71, 2376 (1997)], that comprises a ferromagnetic bilayer as a ferromagnetic component, and an ordinary superconductor as the second interface component, we have realized a full spin switch effect for the superconducting current. An experimental realization of this spin switch construction was achieved for the CoOx/Fe1/Cu/Fe2/In multilayer.

  13. Surface modification of multilayer graphene using Ga ion irradiation

    SciTech Connect

    Wang, Quan; Shao, Ying; Ge, Daohan; Ren, Naifei; Yang, Qizhi

    2015-04-28

    The effect of Ga ion irradiation intensity on the surface of multilayer graphene was examined. Using Raman spectroscopy, we determined that the irradiation caused defects in the crystal structure of graphene. The density of defects increased with the increase in dwell times. Furthermore, the strain induced by the irradiation changed the crystallite size and the distance between defects. These defects had the effect of doping the multilayer graphene and increasing its work function. The increase in work function was determined using contact potential difference measurements. The surface morphology of the multilayer graphene changed following irradiation as determined by atomic force microscopy. Additionally, the adhesion between the atomic force microscopy tip and sample increased further indicating that the irradiation had caused surface modification, important for devices that incorporate graphene.

  14. Atomic scale structure investigations of epitaxial Fe/Cr multilayers

    NASA Astrophysics Data System (ADS)

    Kąc, M.; Morgiel, J.; Polit, A.; Zabila, Y.; Marszałek, M.

    2014-06-01

    Fe/Cr multilayers were deposited by molecular beam epitaxy on the MgO(1 0 0) substrate. Structural properties of the samples were analyzed by low energy electron diffraction, high resolution transmission electron microscopy (HRTEM), as well as by X-ray reflectivity, conversion electron Mössbauer spectroscopy (CEMS) and Auger electron spectroscopy. Investigations revealed multilayered system built of well-ordered Fe and Cr thin films with (1 0 0) orientation. A high geometrical perfection of the system, i.e. planar form of interfaces and reproducible thickness of layers, was also proven. Fe/Cr interface roughness was determined to be 2-3 atomic layers. CEMS studies allowed to analyze at atomic scale the structure of buried Fe/Cr interfaces, as well as to distinguish origin of interface roughness. Roughnesses resulting from interface corrugations and from the Fe-Cr interdiffusion at interfaces were observed. Fe/Cr multilayers showed strong antiferromagnetic coupling of Fe layers.

  15. Applications of Superconductivity

    ERIC Educational Resources Information Center

    Goodkind, John M.

    1971-01-01

    Presents a general review of current practical applications of the properties of superconducters. The devices are classified into groups according to the property that is of primary importance. The article is inteded as a first introduction for students and professionals. (Author/DS)

  16. Levitation Kits Demonstrate Superconductivity.

    ERIC Educational Resources Information Center

    Worthy, Ward

    1987-01-01

    Describes the "Project 1-2-3" levitation kit used to demonstrate superconductivity. Summarizes the materials included in the kit. Discusses the effect demonstrated and gives details on how to obtain kits. Gives an overview of the documentation that is included. (CW)

  17. SUPERCONDUCTING VANADIUM BASE ALLOY

    DOEpatents

    Cleary, H.J.

    1958-10-21

    A new vanadium-base alloy which possesses remarkable superconducting properties is presented. The alloy consists of approximately one atomic percent of palladium, the balance being vanadium. The alloy is stated to be useful in a cryotron in digital computer circuits.

  18. Superconducting thermometer for cryogenics

    NASA Technical Reports Server (NTRS)

    White, F. A.

    1977-01-01

    Digital electronic device uses superconducting filaments as sensors. Simple solid-state circuitry combined with filaments comprise highly-reliable temperature monitor. Device has ability to track very fast thermal transients and "on/off" output is adaptable to remote sensing and telemetry.

  19. Superconducting thermoelectric generator

    DOEpatents

    Metzger, J.D.; El-Genk, M.S.

    1994-01-01

    Thermoelectricity is produced by applying a temperature differential to dissimilar electrically conducting or semiconducting materials, thereby producing a voltage that is proportional to the temperature difference. Thermoelectric generators use this effect to directly convert heat into electricity; however, presently-known generators have low efficiencies due to the production of high currents which in turn cause large resistive heating losses. Some thermoelectric generators operate at efficiencies between 4% and 7% in the 800{degrees} to 1200{degrees}C range. According to its major aspects and bradly stated, the present invention is an apparatus and method for producing electricity from heat. In particular, the invention is a thermoelectric generator that juxtaposes a superconducting material and a semiconducting material - so that the superconducting and the semiconducting materials touch - to convert heat energy into electrical energy without resistive losses in the temperature range below the critical temperature of the superconducting material. Preferably, an array of superconducting material is encased in one of several possible configurations within a second material having a high thermal conductivity, preferably a semiconductor, to form a thermoelectric generator.

  20. AC/RF Superconductivity

    SciTech Connect

    Ciovati, Gianluigi

    2015-02-01

    This contribution provides a brief introduction to AC/RF superconductivity, with an emphasis on application to accelerators. The topics covered include the surface impedance of normal conductors and superconductors, the residual resistance, the field dependence of the surface resistance, and the superheating field.

  1. New research in Superconductivity

    NASA Astrophysics Data System (ADS)

    Khorrami, Mona

    2013-03-01

    Superconductors are materials that have no resistance to electricity's flow; they are one of the last great frontiers of scientific discovery. The theories that explain superconductor behavior seem to be constantly under review. In 1911 superconductivity was first observed in mercury by Dutch physicist Heike Kamerlingh Onnes When he cooled it to the temperature of liquid helium, 4 degrees Kelvin (-452F, -269C), its resistance suddenly disappeared. It was necessary for Onnes to come within 4 degrees of the coldest temperature that is theoretically attainable to witness the phenomenon of superconductivity. In 1933 German researchers Walther Meissner and Robert Ochsenfeld discovered that a superconducting material will repel a magnetic field. A magnet moving by a conductor induces currents in the conductor, but, in a superconductor the induced currents exactly mirror the field that would have otherwise penetrated the superconducting material - causing the magnet to be repulsed. This phenomenon is known as strong diamagnetism and is today often referred to as the ``Meissner effect'' (an eponym). Later on the theory developed by American physicists John Bardeen, Leon Cooper, and John Schrieffer together with extensions and refinements of the theory, which followed in the years after 1957, succeeded in explaining in considerable detail the properties of superconductors.

  2. Magnetoquenched superconducting valve

    NASA Astrophysics Data System (ADS)

    Clinton, T. W.; Johnson, Mark

    1998-06-01

    A superconducting switch has been developed in a simple bilayer cross strip geometry using the magnetic fringe field of a ferromagnetic film to control the critical current in an underlying superconducting bridge. The magnetization of the ferromagnet is rotated in the plane of the film to vary the magnitude of the fringe field locally applied to the superconductor from negligible to substantial values. In the latter case, the magnetization is oriented such that the magnetic poles are along the edges of the cross strip directly above the superconductor. The large fringe field near the poles suppresses superconductivity over a length of order microns, giving rise to superconducting weak link behavior. A large modulation of the critical current is observed. The effect is demonstrated in the low Tc superconductors Pb (Tc=7.3 K) and Sn (Tc=3.9 K). Fabrication of the device involves minimal processing. Applications as a high speed switch, amplifier, nonvolatile storage cell, and controllable weak link are possible.

  3. Multilayer ionic polymer transducer

    NASA Astrophysics Data System (ADS)

    Akle, Barbar J.; Leo, Donald J.

    2003-07-01

    A transducer consisting of multiple layers of ionic polymer material is developed for applications in sensing, actuation, and control. The transducer consists of two to four individual layers each approximately 200 microns thick. The transducers are connected in parallel to minimize the electric field requirements for actuation. The tradeoff in deflection and force can be controlled by controlling the mechanical constraint at the interface. Packaging the transducer in an outer coating produces a hard constraint between layers and reduces the deflection with a force that increases linearly with the number of layers. This configuration also increases the bandwidth of the transducer. Removing the outer packaging produces an actuator that maintains the deflection of a single layer but has an increased force output. This is obtained by allowing the layers to slide relative to one another during bending. Experiments on transducers with one to three layers are performed and the results are compared to Newbury"s equivalent circuit model, which was modified to accommodate the multilayer polymers. The modification was performed on four different boundary conditions, two electrical the series and the parallel connection, and two mechanical the zero interfacial friction and the zero slip on the interface. Results demonstrate that the largest obstacle to obtaining good performance is water transport between the individual layers. Water crossover produces a near short circuit electrical condition and produces feedthrough between actuation layers and sensing layers. Electrical feedthrough due to water crossover eliminates the ability to produce a transducer that has combined sensing and actuation properties. Eliminating water crossover through good insulation enables the development of a small (5 mm x 30 mm) transducer that has sensing and actuation bandwidth on the order of 100 Hz.

  4. Unfolding single- and multilayers

    NASA Astrophysics Data System (ADS)

    Llorens, Maria-Gema; Bons, Paul D.; Griera, Albert; Gomez-Rivas, Enrique

    2014-05-01

    When planar structures (e.g. sedimentary layers, veins, dykes, cleavages, etc.) are subjected to deformation, they have about equal chances to be shortened or stretched. The most common shortening and stretching structures are folds and boudinage, respectively. However, boudinage requires additional deformation mechanisms apart from viscous flow, like formation of fractures or strain localization. When folded layers are subjected to extension, they could potentially unfold back to straight layers. Although probably not uncommon, this would be difficult to recognize. Open questions are whether folded layers can unfold, what determines their mechanical behaviour and how we can recognize them in the field. In order to approach these questions, we present a series of numerical experiments that simulate stretching of previously folded single- and multi-layers in simple shear, using the two dimensional numerical modelling platform ELLE, including the finite element module BASIL that calculates viscous deformation. We investigate the parameters that affect a fold train once it rotates into the extensional field. The results show that the unfolding process strongly depends on the viscosity contrast between the layer and matrix (Llorens et al., 2013). Layers do not completely unfold when they experience softening before or during the stretching process or when other neighbouring competent layers prevent them from unfolding. The foliation refraction patterns are the main indicators of unfolded folds. Additionally, intrafolial folds and cusp-like folds adjacent to straight layers, as well as variations in fold amplitudes and limb lengths of irregular folds can also be used as indicators of stretching of a layer after shortening and folding. References: Llorens, M-.G., Bons, P.D., Griera, A. and Gomez-Rivas, E. 2013. When do folds unfold during progressive shear?. Geology, 41, 563-566.

  5. Suppressed Superconductivity on the Surface of Superconducting RF Quality Niobium for Particle Accelerating Cavities

    SciTech Connect

    Sung, Z. H.; Polyanskii, A. A.; Lee, P. J.; Gurevich, A.; Larbalestier, D. C.

    2011-03-31

    Significant performance degradation of superconducting RF (radio frequency) niobium cavities in high RF field is strongly associated with the breakdown of superconductivity on localized multi-scale surface defects lying within the 40 nm penetration depth. These defects may be on the nanometer scale, like grain boundaries and dislocations or even at the much larger scale of surface roughness and welding pits. By combining multiple superconducting characterization techniques including magneto-optical (MO) imaging and direct transport measurement with non-contact characterization of the surface topology using scanning confocal microscopy, we were able to show clear evidence of suppression of surface superconductivity at chemically treated RF-quality niobium. We found that pinning of vortices along GBs is weaker than pinning of vortices in the grains, which may indicate suppressed superfluid density on GBs. We also directly measured the local magnetic characteristics of BCP-treated Nb sample surface using a micro-Hall sensor in order to further understanding of the effect of surface topological features on the breakdown of superconducting state in RF mode.

  6. Coexistence of superconductivity and ferromagnetism in URhGe.

    PubMed

    Aoki, D; Huxley, A; Ressouche, E; Braithwaite, D; Flouquet, J; Brison, J P; Lhotel, E; Paulsen, C

    2001-10-11

    The discovery of superconductivity at high pressure (albeit over a restricted range) in the ferromagnetic material UGe2 raised the possibility that bulk superconductivity might be found in other ferromagnets. The exact symmetry of the paired state and the dominant mechanism responsible for the pairing, however, remain unidentified. Meanwhile, the conjecture that superconductivity could occur more generally in ferromagnets has been fuelled by the recent observation of a low-temperature transition that suggests an onset of superconductivity in high-quality crystals of the itinerant-ferromagnet ZrZn2 (ref. 2), although the thermodynamic signature of this transition could not be detected. Here we show that the ferromagnet URhGe is superconducting at ambient pressure. In this case, we find the thermodynamic signature of the transition-its form is consistent with a superconducting pairing of a spin-triplet type, although further testing with cleaner samples is needed to confirm this. The combination of superconductivity and ferromagnetism may thus be more common and consequently more important than hitherto realized.

  7. The cryogenic system for ITER CC superconducting conductor test facility

    NASA Astrophysics Data System (ADS)

    Peng, Jinqing; Wu, Yu; Liu, Huajun; Shi, Yi; Chen, Jinglin; Ren, Zhibin

    2011-01-01

    This paper describes the cryogenic system of the International Thermonuclear Experimental Reactor (ITER) Correction Coils (CC) test facility, which consists of a 500 W/4.5 K helium refrigerator, a 50 kA superconducting transformer cryostat (STC) and a background field magnet cryostat (BFMC). The 500 W/4.5 K helium refrigerator synchronously produces both the liquid helium (LHe) and supercritical helium (SHe). The background field magnet and the primary coil of the superconducting transformer (PCST) are cooled down by immersing into 4.2 K LHe. The secondary Cable-In-Conduit Conductor (CICC) coil of the superconducting transformer (SCST), superconducting joints and the testing sample of ITER CC are cooled down by forced-flow supercritical helium. During the commissioning experiment, all the superconducting coils were successfully translated into superconducting state. The background field magnet was fully cooled by immersing it into 4.2 K LHe and generated a maximal background magnetic field of 6.96 T; the temperature of transformer coils and current leads was reduced to 4.3 K; the inlet temperature of SHe loop was 5.6 K, which can meet the cooling requirements of CIC-Conductor and joint boxes. It is noted that a novel heat cut-off device for High Temperature Superconducting (HTS) binary current leads was introduced to reduce the heat losses of transformer cryostat.

  8. Reflectance, Optical Properties, and Stability of Molybdenum/Strontium and Molybdenum/Yttrium Multilayer Mirrors

    SciTech Connect

    Kjornrattanawanich, Benjawan

    2002-09-01

    The motivation of this work is to develop high reflectance normal-incidence multilayer mirrors in the 8-12 nm wavelength region for applications in astronomy and extreme ultraviolet lithography. To achieve this goal, Mo/Sr and Mo/Y multilayers were studied. These multilayers were deposited with a UHV magnetron sputtering system and their reflectances were measured with synchrotron radiation. High normal-incidence reflectances of 23% at 8.8 nm, 40.8% at 9.4 nm, and 48.3% at 10.5 nm were achieved. However, the reflectance of Mo/Sr multilayers decreased rapidly after exposure to air. Attempts to use thin layers of carbon to passivate the surface of Mo/Sr multilayers were unsuccessful. Experimental results on the refractive index $\\tilde{n}$ = 1-δ + iβ of yttrium and molybdenum in the 50-1300 eV energy region are reported in this work. This is the first time ever that values on the refractive index of yttrium are measured in this energy range. The absorption part β was determined through transmittance measurements. The dispersive part δ was calculated by means of the Kramers-Kronig formalism. The newly determined values of the refractive index of molybdenum are in excellent agreement with the published data. Those of yttrium are more accurate and contain fine structures around the yttrium M-absorption edges where Mo/Y multilayers operate. These improved sets of optical data lead to better design and modeling of the optical properties of Mo/Y multilayers. The reflectance quality of Mo/Y multilayers is dependent on their optical and structural properties. To correlate these properties with the multilayer reflectance, x-ray diffraction, Rutherford backscattering spectrometry, and transmission electron microscopy were used to analyze samples. Normal-incidence reflectances of 32.6% at 9.27 nm, 38.4% at 9.48 nm, and 29.6% at 9.46 nm were obtained from three representative Mo/Y multilayers which had about 0%, 25%, and 39% atomic oxygen assimilated in their yttrium layers

  9. A Superconducting transformer system for high current cable testing

    SciTech Connect

    Godeke, A.; Dietderich, D. R.; Joseph, J. M.; Lizarazo, J.; Prestemon, S. O.; Miller, G.; Weijers, H. W.

    2010-02-15

    This article describes the development of a direct-current (dc) superconducting transformer system for the high current test of superconducting cables. The transformer consists of a core-free 10 464 turn primary solenoid which is enclosed by a 6.5 turn secondary. The transformer is designed to deliver a 50 kA dc secondary current at a dc primary current of about 50 A. The secondary current is measured inductively using two toroidal-wound Rogowski coils. The Rogowski coil signal is digitally integrated, resulting in a voltage signal that is proportional to the secondary current. This voltage signal is used to control the secondary current using a feedback loop which automatically compensates for resistive losses in the splices to the superconducting cable samples that are connected to the secondary. The system has been commissioned up to 28 kA secondary current. The reproducibility in the secondary current measurement is better than 0.05% for the relevant current range up to 25 kA. The drift in the secondary current, which results from drift in the digital integrator, is estimated to be below 0.5 A/min. The system's performance is further demonstrated through a voltage-current measurement on a superconducting cable sample at 11 T background magnetic field. The superconducting transformer system enables fast, high resolution, economic, and safe tests of the critical current of superconducting cable samples.

  10. A superconducting transformer system for high current cable testing.

    PubMed

    Godeke, A; Dietderich, D R; Joseph, J M; Lizarazo, J; Prestemon, S O; Miller, G; Weijers, H W

    2010-03-01

    This article describes the development of a direct-current (dc) superconducting transformer system for the high current test of superconducting cables. The transformer consists of a core-free 10,464 turn primary solenoid which is enclosed by a 6.5 turn secondary. The transformer is designed to deliver a 50 kA dc secondary current at a dc primary current of about 50 A. The secondary current is measured inductively using two toroidal-wound Rogowski coils. The Rogowski coil signal is digitally integrated, resulting in a voltage signal that is proportional to the secondary current. This voltage signal is used to control the secondary current using a feedback loop which automatically compensates for resistive losses in the splices to the superconducting cable samples that are connected to the secondary. The system has been commissioned up to 28 kA secondary current. The reproducibility in the secondary current measurement is better than 0.05% for the relevant current range up to 25 kA. The drift in the secondary current, which results from drift in the digital integrator, is estimated to be below 0.5 A/min. The system's performance is further demonstrated through a voltage-current measurement on a superconducting cable sample at 11 T background magnetic field. The superconducting transformer system enables fast, high resolution, economic, and safe tests of the critical current of superconducting cable samples.

  11. A study on the effect of tantalum-impurity content on the superconducting properties of niobium materials used for making superconducting radio frequency cavities

    SciTech Connect

    S B Roy, L S Sharath Chandra, M K Chattopadhyay, M K Tiwari, G S Lodha, G R Myneni

    2012-10-01

    Niobium materials in highly pure form are used in the fabrication of superconducting radio frequency cavities. We present here a study of the superconducting properties of such niobium materials that have been used in the fabrication of high accelerating gradient superconducting radio frequency cavities after determining their tantalum-impurity contents using a synchrotron-based x-ray fluorescence spectroscopy technique. Our results show that there is a small change in superconducting parameters such as T{sub C},H{sub C1} and H{sub C2} when the tantalum-impurity content varies from ≈150 to ≈1300 ppm. In contrast, a buffered chemical polishing of the same niobium samples changes all these superconducting parameters more significantly. The implications of these results on the performance of niobium superconducting radio frequency cavities are discussed.

  12. Magnetic proximity effect in perovskite superconductor/ferromagnet multilayers

    NASA Astrophysics Data System (ADS)

    Stahn, J.; Chakhalian, J.; Niedermayer, Ch.; Hoppler, J.; Gutberlet, T.; Voigt, J.; Treubel, F.; Habermeier, H.-U.; Cristiani, G.; Keimer, B.; Bernhard, C.

    2005-04-01

    Multilayers of superconducting/ferromagnetic (SC/FM) YBa2Cu3O7/La2/3Ca1/3MnO3 have been studied by neutron reflectometry. The occurrence of a structurally forbidden Bragg peak in the FM state highlights a significant difference between the nuclear and magnetic depth profiles. From comparison with simulated reflectivity curves we identify two possible magnetization profiles: (i) a magnetic moment within the SC layer antiparallel to the one in the FM layer (antiphase magnetic proximity effect) or (ii) a “dead” region in the FM layer with zero net magnetic moment. In addition, we observe an anomalous enhancement of the off-specular reflection in the SC state which signals a strong mutual interaction between SC and FM order parameters.

  13. Structural reducibility of multilayer networks

    NASA Astrophysics Data System (ADS)

    de Domenico, Manlio; Nicosia, Vincenzo; Arenas, Alexandre; Latora, Vito

    2015-04-01

    Many complex systems can be represented as networks consisting of distinct types of interactions, which can be categorized as links belonging to different layers. For example, a good description of the full protein-protein interactome requires, for some organisms, up to seven distinct network layers, accounting for different genetic and physical interactions, each containing thousands of protein-protein relationships. A fundamental open question is then how many layers are indeed necessary to accurately represent the structure of a multilayered complex system. Here we introduce a method based on quantum theory to reduce the number of layers to a minimum while maximizing the distinguishability between the multilayer network and the corresponding aggregated graph. We validate our approach on synthetic benchmarks and we show that the number of informative layers in some real multilayer networks of protein-genetic interactions, social, economical and transportation systems can be reduced by up to 75%.

  14. Multilayer adsorption on fractal surfaces.

    PubMed

    Vajda, Péter; Felinger, Attila

    2014-01-10

    Multilayer adsorption is often observed in liquid chromatography. The most frequently employed model for multilayer adsorption is the BET isotherm equation. In this study we introduce an interpretation of multilayer adsorption measured on liquid chromatographic stationary phases based on the fractal theory. The fractal BET isotherm model was successfully used to determine the apparent fractal dimension of the adsorbent surface. The nonlinear fitting of the fractal BET equation gives us the estimation of the adsorption equilibrium constants and the monolayer saturation capacity of the adsorbent as well. In our experiments, aniline and proline were used as test molecules on reversed phase and normal phase columns, respectively. Our results suggest an apparent fractal dimension 2.88-2.99 in the case of reversed phase adsorbents, in the contrast with a bare silica column with a fractal dimension of 2.54.

  15. Heat Transfer In High-Temperature Multilayer Insulation

    NASA Technical Reports Server (NTRS)

    Daryabeigi, Kamran; Miller, Stephen D.; Cunnington, George R.

    2006-01-01

    The combined radiation/conduction heat transfer in high-temperature multilayer insulations for typical reentry of reusable launch vehicles from low Earth orbit was investigated experimentally and numerically. The high-temperature multilayer insulation investigated consisted of gold-coated reflective foils separated by alumina fibrous insulation spacers. The steady-state heat transfer through four multilayer insulation configurations was investigated experimentally over the temperature range of 300-1300 K and environmental pressure range of 1.33 10(exp -5)-101.32 kPa. It was shown that including the reflective foils reduced the effective thermal conductivity compared to fibrous insulation sample at 1.5 times the density of the multilayer sample. A finite volume numerical model was developed to solve the governing combined radiation/conduction heat transfer equations. The radiation heat transfer in the fibrous insulation spacers was modeled using the modified two-flux approximation assuming anisotropic scattering and gray medium. The numerical model was validated by comparison with steady-state experimental data. The root mean square deviation between the predicted and measured effective thermal conductivity of the samples was 9.5%.

  16. Photolithographically patterened thin-film multilayer devices of YBa sub 2 Cu sub 3 O sub 7-x

    SciTech Connect

    Kingston, J.J.; Wellstood, F.C.; Quan, D.; Clarke, J.

    1990-09-01

    We have fabricated thin-film YBa{sub 2}Cu{sub 3}O{sub 7-x}-SrTiO{sub 3}-YBa{sub 2}Cu{sub 3}O{sub 7-x} multilayer interconnect structures in which each in situ laser-deposited film is independently patterned by photolithography. In particular, we have constructed the two key components necessary for a superconducting multilayer interconnect technology, crossovers and window contacts. As a further demonstration of the technology, we have fabricated a thin-film flux transformer, suitable for use with a Superconducting QUantum Interference Device (SQUID), that includes a ten-turn input coil with 6{mu}m linewidth. Transport measurements showed that the critical temperature was 87K and the critical current was 135 {mu}A at 82K. 7 refs., 6 figs.

  17. Ferromagnetic resonance measurements of (Co/Ni/Co/Pt) multilayers with perpendicular magnetic anisotropy

    NASA Astrophysics Data System (ADS)

    Sbiaa, R.; Shaw, J. M.; Nembach, H. T.; Bahri, M. Al; Ranjbar, M.; Åkerman, J.; Piramanayagam, S. N.

    2016-10-01

    Multilayers of [Co/Ni(t)/Co/Pt]×8 with varying Ni thickness were investigated for possible use as a free layer in magnetic tunnel junctions and spintronics devices. The thickness t of the Ni sub-layer was varied from 0.3 nm to 0.9 nm and the resulting magnetic properties were compared with (Co/Ni) and (Co/Pt) multilayers. As determined from magnetic force microscopy, magnetometry and ferromagnetic resonance measurements, all multilayers exhibited perpendicular magnetic anisotropy. Compared with (Co/Pt) multilayers, the sample with t of 0.9 nm showed almost the same anisotropy field of μ 0 H k   =  1.15 T but the damping constant was 40% lower. These characteristics make these multilayers attractive for spin torque based magnetoresistive devices with perpendicular anisotropy.

  18. Experimental investigation of the role of the triplet pairing in the superconducting spin-valve effect

    NASA Astrophysics Data System (ADS)

    Leksin, P. V.; Kamashev, A. A.; Garif'yanov, N. N.; Validov, A. A.; Fominov, Ya. V.; Schumann, J.; Kataev, V. E.; Büchner, B.; Garifullin, I. A.

    2016-11-01

    An important role of the morphology of a superconducting layer in the superconducting spin-valve effect has been established. The triplet pairing induced by the superconductor/ferromagnet proximity effect has been experimentally investigated for samples CoO x /Py1/Cu/Py2/Cu/Pb (where Py = Ni0.81Fe0.19) with a smooth superconducting layer. The optimization of the parameters of this structure has demonstrated a complete switching between the normal and superconducting states with a change in the relative orientation of magnetizations of the ferromagnetic layers from the antiparallel to orthogonal orientation. A pure triplet contribution has been observed for the sample with a permalloy layer thickness at which the superconducting spin-valve effect vanishes. A direct comparison of the experimental data with the theoretical calculation of the temperature of the transition to the superconducting state has been performed for the first time.

  19. Automated conductivity profiler for multilayer GaAs-(AlGa)As structures

    NASA Astrophysics Data System (ADS)

    Stiles, K. R.; Lee, J. W.

    1982-09-01

    An apparatus for automatic conductivity profiling of GaAs-(AlGa)As multilayer structures is described. The apparatus includes a microprocessor which controls a solenoid valve sequence in order to chemically etch the sample, and a programmable calculator which calculates sample conductance versus number of etch steps from which layer conductivities are calculated. Conductivity profiles of multilayer GaAs-(AlGa)As heterostructure laser material are presented and compared to profiles done by an earlier manual technique.

  20. Superconductivity in Cuba: Reaching the Frontline

    NASA Astrophysics Data System (ADS)

    Arés Muzio, Oscar; Altshuler, Ernesto

    The start of experimental research in the field of superconductivity was a very special moment for Cuban physics: Cuban scientists at the Physics Faculty, University of Havana, synthesized the first Cuban superconductor (a 123-YBCO ceramic sample) just 2 months after the publication of the famous paper by Wu and co-workers that triggered the frantic race of High Tc superconductors all over the world. We timely joined the world's frontline in superconductor research.

  1. Method for detecting superconducting stripes in high-temperature superconductors based on nonlinear resistivity measurements.

    PubMed

    Muniz, Rodrigo A; Martin, Ivar

    2011-09-16

    We theoretically study the effect that stripelike superconducting inclusions would have on the nonlinear resistivity in single crystals. Even if the stripe orientation varies throughout the sample between two orthogonal directions due to twinning, we predict that there should be a universal dependence of the nonlinear resistivity on the angle between the applied current and the crystal axes. This prediction can be used to test the existence of superconducting stripes at and above the superconducting transition temperature in cuprate superconductors.

  2. Micromechanical Properties of Nanostructured Clay-Oxide Multilayers Synthesized by Layer-by-Layer Self-Assembly

    PubMed Central

    Hou, Dongwei; Zhang, Guoping; Pant, Rohit Raj; Wei, Zhongxin; Shen, Shuilong

    2016-01-01

    Clay-based nanostructured multilayers, such as clay-polymer multilayers and clay-oxide multilayers, have attracted growing attention owing to their remarkable mechanical properties and promising application in various fields. In this paper, synthesis of a new kind of nanostructured clay-oxide multilayers by layer-by-layer self-assembly was explored. Nano-mechanical characterization of 18 clay-based multilayer samples, prepared under as-deposited (i.e., air-dried) and annealing conditions at 400 °C/600 °C with different precursor cations and multilayer structure, were carried out using nanoindentation testing, atomic force microscopy (AFM), and X-ray diffraction (XRD). The influencing factors, including as-deposited and annealing conditions and clay concentrations on the mechanical properties were analyzed. Results show that all of the multilayers exhibit high bonding strength between interlayers. Higher modulus and hardness of clay-based multilayers were obtained with lower clay concentrations than that with higher clay concentrations. Different relationships between the modulus and hardness and the annealing temperature exist for a specific type of clay-oxide multilayer. This work offers the basic and essential knowledge on design of clay-based nanostructured multilayers by layer-by-layer self-assembly. PMID:28335332

  3. Micromechanical Properties of Nanostructured Clay-Oxide Multilayers Synthesized by Layer-by-Layer Self-Assembly.

    PubMed

    Hou, Dongwei; Zhang, Guoping; Pant, Rohit Raj; Wei, Zhongxin; Shen, Shuilong

    2016-11-08

    Clay-based nanostructured multilayers, such as clay-polymer multilayers and clay-oxide multilayers, have attracted growing attention owing to their remarkable mechanical properties and promising application in various fields. In this paper, synthesis of a new kind of nanostructured clay-oxide multilayers by layer-by-layer self-assembly was explored. Nano-mechanical characterization of 18 clay-based multilayer samples, prepared under as-deposited (i.e., air-dried) and annealing conditions at 400 °C/600 °C with different precursor cations and multilayer structure, were carried out using nanoindentation testing, atomic force microscopy (AFM), and X-ray diffraction (XRD). The influencing factors, including as-deposited and annealing conditions and clay concentrations on the mechanical properties were analyzed. Results show that all of the multilayers exhibit high bonding strength between interlayers. Higher modulus and hardness of clay-based multilayers were obtained with lower clay concentrations than that with higher clay concentrations. Different relationships between the modulus and hardness and the annealing temperature exist for a specific type of clay-oxide multilayer. This work offers the basic and essential knowledge on design of clay-based nanostructured multilayers by layer-by-layer self-assembly.

  4. High-Temperature Superconductivity and Lattice Relaxation in Lithium-Deposited FeSe on SrTiO3

    NASA Astrophysics Data System (ADS)

    Phan, Giao N.; Nakayama, Kosuke; Kanayama, Shota; Kuno, Masato; Sugawara, Katsuaki; Sato, Takafumi; Takahashi, Takashi

    2017-03-01

    We studied the effect of strain, interface, and electron doping on the superconductivity in thin FeSe film on SrTiO3 by angle-resolved photoemission spectroscopy (ARPES). We observed the superconductivity with Tc as high as 43 K in a lithium (Li) deposited heavily electron-doped multilayer FeSe film. We found a significant relaxation of tensile strain at the surface in contrast to the case of potassium (K) deposition, although the high-Tc superconductivity is commonly observed in both cases. We discuss the interplay among carrier doping, tensile strain, and high-Tc superconductivity by comparing ARPES results on Li- and K-deposited FeSe films.

  5. Optimized Geometry for Superconducting Sensing Coils

    NASA Technical Reports Server (NTRS)

    Eom, Byeong Ho; Pananen, Konstantin; Hahn, Inseob

    2008-01-01

    An optimized geometry has been proposed for superconducting sensing coils that are used in conjunction with superconducting quantum interference devices (SQUIDs) in magnetic resonance imaging (MRI), magnetoencephalography (MEG), and related applications in which magnetic fields of small dipoles are detected. In designing a coil of this type, as in designing other sensing coils, one seeks to maximize the sensitivity of the detector of which the coil is a part, subject to geometric constraints arising from the proximity of other required equipment. In MRI or MEG, the main benefit of maximizing the sensitivity would be to enable minimization of measurement time. In general, to maximize the sensitivity of a detector based on a sensing coil coupled with a SQUID sensor, it is necessary to maximize the magnetic flux enclosed by the sensing coil while minimizing the self-inductance of this coil. Simply making the coil larger may increase its self-inductance and does not necessarily increase sensitivity because it also effectively increases the distance from the sample that contains the source of the signal that one seeks to detect. Additional constraints on the size and shape of the coil and on the distance from the sample arise from the fact that the sample is at room temperature but the coil and the SQUID sensor must be enclosed within a cryogenic shield to maintain superconductivity.

  6. Giant superconductivity-induced modulation of the ferromagnetic magnetization in a cuprate-manganite superlattice.

    PubMed

    Hoppler, J; Stahn, J; Niedermayer, Ch; Malik, V K; Bouyanfif, H; Drew, A J; Rössle, M; Buzdin, A; Cristiani, G; Habermeier, H-U; Keimer, B; Bernhard, C

    2009-04-01

    Artificial multilayers offer unique opportunities for combining materials with antagonistic orders such as superconductivity and ferromagnetism and thus to realize novel quantum states. In particular, oxide multilayers enable the utilization of the high superconducting transition temperature of the cuprates and the versatile magnetic properties of the colossal-magnetoresistance manganites. However, apart from exploratory work, the in-depth investigation of their unusual properties has only just begun. Here we present neutron reflectometry measurements of a [Y(0.6)Pr(0.4)Ba(2)Cu(3)O(7) (10 nm)/La(2/3)Ca(1/3)MnO(3) (10 nm)](10) superlattice, which reveal a surprisingly large superconductivity-induced modulation of the vertical ferromagnetic magnetization profile. Most surprisingly, this modulation seems to involve the density rather than the orientation of the magnetization and is highly susceptible to the strain, which is transmitted from the SrTiO(3) substrate. We outline a possible explanation of this unusual superconductivity-induced phenomenon in terms of a phase separation between ferromagnetic and non-ferromagnetic nanodomains in the La(2/3)Ca(1/3)MnO(3) layers.

  7. Superconductivity in sputtered CuMo6S8

    NASA Technical Reports Server (NTRS)

    Alterovitz, S.; Woollam, J. A.; Kammerdiner, L.; Luo, H.-L.; Martin, C.

    1977-01-01

    The superconducting transition temperature and the superconducting upper critical fields for sputtered films of copper-containing ternary molybdenum chalcogenides (chevrel phases) were determined. The theory presented by Werthamer, Helfand, and Hohenberg (WHH) (1966) was used to make computer-generated plots of the superconducting upper critical field values versus the superconducting transition temperature values for various values of the Maki paramagnetic pair-breaking parameter and the spin-orbit scattering parameter. The interpretation of the graph suggests that the experimental data for at least one sample are above the maximum WHH theoretical limit in the lower temperature range. Possible explanations of this situation are discussed. In other calculations, a scaling law was found suitable for determining pinning force densities; this data was used to calculate critical current values. The relation between resistivity and temperature was studied.

  8. Superconductivity in the alkali metal intercalates of molybdenum disulphide

    NASA Technical Reports Server (NTRS)

    Somoano, R. B.; Hadek, V.; Rembaum, A.

    1972-01-01

    The complete series of alkali metals, lithium through cesium, have been intercalated into molybdenum disulphide, using both the liquid ammonia and vapor techniques. All the intercalates with the exception of lithium yielded full superconducting transitions with onset temperatures of 6 K for AxMoS2(Ax=K,Rb,Cs) and 4 K for BxMoS2(Bx=Li,Na). The superconducting transition for lithium was incomplete down to 1.5 K. Stoichiometries and unit cell parameters have been determined for the intercalation compounds. Both rhombohedral and hexagonal polymorphs of MoS2 have been intercalated and found to exhibit the same superconductivity behavior. The nature of the extraneous superconducting transition of some intercalated samples on exposure to air was elucidated.

  9. Towards a better understanding of superconductivity at high transition temperatures

    NASA Astrophysics Data System (ADS)

    Hackl, R.; Hanke, W.

    2010-10-01

    We provide an overview over the following eleven contributions on superconductivity in copper-oxygen and iron-based compounds. The main objective of this volume is an improved general understanding of superconductivity at high transition temperatures. The key questions on the way towards understanding superconducting pairing beyond electron-phonon coupling are spelled out, and the present status of theoretical reasoning is summarized. The crucial experiments, their results and interrelations are discussed. The central result is that fluctuations of spin and charge contribute substantially to superconductivity and also to other ordering phenomena. Methodically, the simultaneous analysis of results obtained from different experimental techniques such as photoelectron spectroscopy and neutron scattering, on one and the same sample, turned out to be of pivotal importance.

  10. Odd-parity superconductivity by competing spin-orbit coupling and orbital effect in artificial heterostructures

    NASA Astrophysics Data System (ADS)

    Watanabe, Tatsuya; Yoshida, Tomohiro; Yanase, Youichi

    2015-11-01

    We show that odd-parity superconductivity occurs in multilayer Rashba systems without requiring spin-triplet Cooper pairs. A pairing interaction in the spin-singlet channel stabilizes the odd-parity pair-density-wave (PDW) state in the magnetic field parallel to the two-dimensional conducting plane. It is shown that the layer-dependent Rashba spin-orbit coupling and the orbital effect play essential roles for the PDW state in binary and tricolor heterostructures. We demonstrate that the odd-parity PDW state is a symmetry-protected topological superconducting state characterized by the one-dimensional winding number in the symmetry class BDI. The superconductivity in the artificial heavy-fermion superlattice CeCoIn5/YbCoIn5 and bilayer interface SrTiO3/LaAlO3 is discussed.

  11. Superconductivity in graphite intercalation compounds

    DOE PAGES

    Smith, Robert P.; Weller, Thomas E.; Howard, Christopher A.; ...

    2015-02-26

    This study examines the field of superconductivity in the class of materials known as graphite intercalation compounds which has a history dating back to the 1960s. This paper recontextualizes the field in light of the discovery of superconductivity in CaC₆ and YbC₆ in 2005. In what follows, we outline the crystal structure and electronic structure of these and related compounds. We go on to experiments addressing the superconducting energy gap, lattice dynamics, pressure dependence, and how this relates to theoretical studies. The bulk of the evidence strongly supports a BCS superconducting state. However, important questions remain regarding which electronic statesmore » and phonon modes are most important for superconductivity and whether current theoretical techniques can fully describe the dependence of the superconducting transition temperature on pressure and chemical composition.« less

  12. Superconductivity in graphite intercalation compounds

    SciTech Connect

    Smith, Robert P.; Weller, Thomas E.; Howard, Christopher A.; Dean, Mark P. M.; Rahnejat, Kaveh C.; Saxena, Siddharth S.; Ellerby, Mark

    2015-02-26

    This study examines the field of superconductivity in the class of materials known as graphite intercalation compounds which has a history dating back to the 1960s. This paper recontextualizes the field in light of the discovery of superconductivity in CaC₆ and YbC₆ in 2005. In what follows, we outline the crystal structure and electronic structure of these and related compounds. We go on to experiments addressing the superconducting energy gap, lattice dynamics, pressure dependence, and how this relates to theoretical studies. The bulk of the evidence strongly supports a BCS superconducting state. However, important questions remain regarding which electronic states and phonon modes are most important for superconductivity and whether current theoretical techniques can fully describe the dependence of the superconducting transition temperature on pressure and chemical composition.

  13. Tunable superconductivity in decorated graphene

    NASA Astrophysics Data System (ADS)

    Han, Zheng; Allain, Adrien; Marty, Laetitia; Bendiab, Nedjma; Toulemonde, Pierre; Strobel, Pierre; Coraux, Johann; Bouchiat, Vincent

    2013-03-01

    Graphene offers an exposed bidimensional gas of high mobility charge carriers with gate tunable density. Its chemical inertness offers an outstanding platform to explore exotic 2D superconductivity. Superconductivity can be induced in graphene by means of proximity effect (by depositing a set of superconducting metal clusters such as lead or tin nanoparticles). The influence of decoration material, density or particles and disorder of graphene will be discussed. In the case of disordered graphene, Tin decoration leads to a gate-tunable superconducting-to-insulator quantum phase transition. Superconductivity in graphene is also expected to occur under strong charge doping (induced either by gating or under chemical decoration, in analogy with graphite intercalated compounds). I will also show preliminary results showing the influence of Calcium intercalation of few layer graphene and progress toward the demonstration of intrinsic superconductivity in such systems. Work supported by EU GRANT FP7-NMP GRENADA.

  14. Superconducting miniaturized planar antennas

    NASA Astrophysics Data System (ADS)

    Pischke, A.; Chaloupka, H.; Klein, N.; Splitt, G.

    This contribution reports on experimental as well as theoretical investigations of superconducting 2.4 GHz microstrip antenna. Due to both a new stepped-impedance patch shape and a high permittivity substrate (LaAlO3) the size was reduced to an area of only 6x6 mm. The measured radiation efficiency of antennas fabricated from YBa2Cu3O(7-delta) is at 77 K in the order of 45 and 65 percent for a substrate height of 0.5 mm and 1 mm respectively. In contrast, a copper antenna yields an efficiency of 3 and 6 percent only. Deviations from a linear transmission behavior of the superconducting antenna can be observed at a current density of 500,000 A/sq cm. An increase in frequency bandwidth from 4 MHz to over 9 MHz results from replacing the single-patch structure by a double-patch structure (stacked patches).

  15. Superconducting multipole corrector magnet

    SciTech Connect

    Kashikhin, Vladimir; /Fermilab

    2004-10-01

    A novel concept of superconducting multipole corrector magnet is discussed. This magnet assembled from 12 identical racetrack type coils and can generate any combination of dipole, quadrupole and sextupole magnetic fields. The coil groups are powered from separate power supplies. In the case of normal dipole, quadrupole and sextupole fields the total field is symmetrical relatively the magnet median plane and there are only five powered separately coil groups. This type multipole corrector magnet was proposed for BTeV, Fermilab project and has following advantages: universal configuration, simple manufacturing and high mechanical stability. The results of magnetic design including the field quality and magnetic forces in comparison with known shell type superconducting correctors are presented.

  16. Radial transmission line analysis of multi-layer structures

    SciTech Connect

    Hahn, H.; Hammons, L.

    2011-03-28

    The analysis of multi-layer beam tubes is a standard problem and involves axially propagating waves. This treatment is ill suited to a short multi-layer structure such as the present example of a ferrite covered ceramic break in the beam tube at the ERL photo-cathode electron gun. This paper demonstrates that such structure can better be treated by radial wave propagation. The theoretical method is presented and numerical results are compared with measured network analyser data and Microwave Studio generated simulations. The results confirm the concept of radial transmission lines as a valid analytical method. An Energy Recovery Linac (ERL) is being constructed at this laboratory for the purpose of research towards an envisioned Electron Ion Collider. One of the pertinent topics is damping of Higher Order Modes (HOM). In this ERL, the damping is provided by ferrite absorbers in the beam tube. A modified version thereof, a ceramic break surrounded by ferrite, is planed for the superconducting electron gun. The damper here is located at room temperature just outside of the gun. If used in a cavity chain, the ceramic break is in the vacuum tube at helium temperature whereas the ferrite is moved into the cryostat insulating vacuum allowing higher temperatures. The general properties of the ferrite HOM dampers have been published but are more detailed in this paper.

  17. Superconducting magnet wire

    DOEpatents

    Schuller, Ivan K.; Ketterson, John B.; Banerjee, Indrajit

    1986-01-01

    A superconducting tape or wire with an improved critical field is formed of alternating layers of a niobium-containing superconductor such as Nb, NbTi, Nb.sub.3 Sn or Nb.sub.3 Ge with a thickness in the range of about 0.5-1.5 times its coherence length, supported and separated by layers of copper with each copper layer having a thickness in the range of about 170-600 .ANG..

  18. Superconducting terahertz metamaterials

    SciTech Connect

    Chen, Hou-tong; Singh, Ranjan; O' Hara, John F; Azad, Abul K; Trugman, Stuart A; Jia, Quanxi; Taylor, Antoinette J

    2010-01-01

    During the past ten years subwavelength metallic structures have enabled metamaterials exhibiting exotic physical properties that are not possible or difficult to realize using naturally occurring materials, This bottom-up metamaterial approach is particularly attractive in the terahertz (THz) frequency range, where the THz gap is inherently associated with the lack of materials with appropriate reponse. In fact THz metamaterial devices have accomplished unprecedented performance towards practical applications. In these devices, the key is to incorporate natural materials, e,g, semiconductors, as the metamaterial substrates or integration parts of metamaterial structures. The active or dynamic tunability of metamaterials is through the application of external stimuli such as temperature, photoexcitation, or electric field. to modify the capacitive gaps in split-ring resonators (SRRs), It becomes clear that we would not be able to do much on the metallic SRRs, i.e. the metal conductivity and therefore the inductance largely remain constant not affected by external stimuli. Recently, there has been increasing interest in superconducting metamaterials towards loss reduction. Significant Joule losses have often prevented resonant metal metamaterials from achieving proposed applications. particularly in the optical frequency range. At low temperatures, superconducting materials possess superior conductivity than metals at frequencies up to THz. and therefore it is expected that superconducting melamaterials will have a lower loss than metal metamatetials, More interestingly, superconductors exhibit tunable complex conductivity over a wide range of values through change of temperature and application of photoexcitation, electrical currents and magnetic fields. Therefore, we would expect correspondingly tunable metamaterials. which originate from the superconducting materials composing the metamaterial, in contrast to tuning the metamaterial embedded environment.

  19. Fringe Field Superconducting Switch

    DTIC Science & Technology

    1997-10-31

    superconducting smp ,ine 10, and a ferromagnet ferromagnet 14 preferably has at least two easy axes of magnetization, shown here by the double- headed arrows...magnetic field of control current **p6fCooductor- S4 ’’/ eonteol^cun 7* insulator ■O Jöpptyzcöwem supercuiKhttstog-^2 ^ FIG.^ 4 //■ r.»~r

  20. Multilayer High-Gradient Insulators

    SciTech Connect

    Harris, J R

    2006-08-16

    Multilayer High-Gradient Insulators are vacuum insulating structures composed of thin, alternating layers of dielectric and metal. They are currently being developed for application to high-current accelerators and related pulsed power systems. This paper describes some of the High-Gradient Insulator research currently being conducted at Lawrence Livermore National Laboratory.

  1. A 200 SUPERCONDUCTING RACETRACK MICROTRON,

    DTIC Science & Technology

    A race-track microtron is proposed consisting of two 180 degree magnets spaced 2.5 meters apart with a superconducting linac section between. The...MeV per turn. The electrons are injected into the microtron at about 12 MeV from a second superconducting accelerator section. The spacing between...superconducting linac sections, a beam current of 100 microamps at unity duty cycle is feasible. It is also possible to build the microtron using

  2. Silicon superconducting quantum interference device

    SciTech Connect

    Duvauchelle, J. E.; Francheteau, A.; Marcenat, C.; Lefloch, F.; Chiodi, F.; Débarre, D.; Hasselbach, K.; Kirtley, J. R.

    2015-08-17

    We have studied a Superconducting Quantum Interference Device (SQUID) made from a single layer thin film of superconducting silicon. The superconducting layer is obtained by heavily doping a silicon wafer with boron atoms using the gas immersion laser doping technique. The SQUID is composed of two nano-bridges (Dayem bridges) in a loop and shows magnetic flux modulation at low temperature and low magnetic field. The overall behavior shows very good agreement with numerical simulations based on the Ginzburg-Landau equations.

  3. Superconducting Analog to Digital Converters

    DTIC Science & Technology

    1991-09-01

    superconductivity, Josephson junctions, and superconducting quantum interference devices ( SQUIDs ) are briefly described. Various techniques to perform analog-to...deployment in the 1990s may require a dynamic range in excess of 90 dB (15- bit precision) [3]. However, at the present time, A/D conversion with 16-bit...Interference Devices ( SQUIDs ). JOSEPHSON EFFECTS AND JUNCTIONS Consider a very thin, non-superconducting region separating two superconductors. In 1962

  4. Multilayer Composite Pressure Vessels

    NASA Technical Reports Server (NTRS)

    DeLay, Tom

    2005-01-01

    A method has been devised to enable the fabrication of lightweight pressure vessels from multilayer composite materials. This method is related to, but not the same as, the method described in gMaking a Metal- Lined Composite-Overwrapped Pressure Vessel h (MFS-31814), NASA Tech Briefs, Vol. 29, No. 3 (March 2005), page 59. The method is flexible in that it poses no major impediment to changes in tank design and is applicable to a wide range of tank sizes. The figure depicts a finished tank fabricated by this method, showing layers added at various stages of the fabrication process. In the first step of the process, a mandrel that defines the size and shape of the interior of the tank is machined from a polyurethane foam or other suitable lightweight tooling material. The mandrel is outfitted with metallic end fittings on a shaft. Each end fitting includes an outer flange that has a small step to accommodate a thin layer of graphite/epoxy or other suitable composite material. The outer surface of the mandrel (but not the fittings) is covered with a suitable release material. The composite material is filament- wound so as to cover the entire surface of the mandrel from the step on one end fitting to the step on the other end fitting. The composite material is then cured in place. The entire workpiece is cut in half in a plane perpendicular to the axis of symmetry at its mid-length point, yielding two composite-material half shells, each containing half of the foam mandrel. The halves of the mandrel are removed from within the composite shells, then the shells are reassembled and bonded together with a belly band of cured composite material. The resulting composite shell becomes a mandrel for the subsequent steps of the fabrication process and remains inside the final tank. The outer surface of the composite shell is covered with a layer of material designed to be impermeable by the pressurized fluid to be contained in the tank. A second step on the outer flange of

  5. Chiral magnetic superconductivity

    NASA Astrophysics Data System (ADS)

    Kharzeev, Dmitri E.

    2017-03-01

    Materials with charged chiral quasiparticles in external parallel electric and magnetic fields can support an electric current that grows linearly in time, corresponding to diverging DC conductivity. From experimental viewpoint, this "Chiral Magnetic Superconductivity" (CMS) is thus analogous to conventional superconductivity. However the underlying physics is entirely different - the CMS does not require a condensate of Cooper pairs breaking the gauge degeneracy, and is thus not accompanied by Meissner effect. Instead, it owes its existence to the (temperature-independent) quantum chiral anomaly and the conservation of chirality. As a result, this phenomenon can be expected to survive to much higher temperatures. Even though the chirality of quasiparticles is not strictly conserved in real materials, the chiral magnetic superconductivity should still exhibit itself in AC measurements at frequencies larger than the chirality-flipping rate, and in microstructures of Dirac and Weyl semimetals with thickness below the mean chirality-flipping length that is about 1 - 100 μm. In nuclear physics, the CMS should contribute to the charge-dependent elliptic flow in heavy ion collisions.

  6. Navy superconductivity efforts

    NASA Technical Reports Server (NTRS)

    Gubser, D. U.

    1990-01-01

    Both the new high temperature superconductors (HTS) and the low temperature superconductors (LTS) are important components of Navy's total plan to integrate superconductivity into field operational systems. Fundamental research is an important component of the total Navy program and focuses on the HTS materials. Power applications (ship propulsion, etc.) use LTS materials while space applications (MMW electronics, etc.) use HTS materials. The Space Experiment being conducted at NRL will involve space flight testing of HTS devices built by industry and will demonstrate the ability to engineer and space qualify these devices for systems use. Another important component of the Navy's effort is the development of Superconducting Quantum Interference Device (SQUID) magnetometers. This program will use LTS materials initially, but plans to implement HTS materials as soon as possible. Hybrid HTS/LTS systems are probable in many applications. A review of the status of the Navy's HTS materials research is given as well as an update on the Navy's development efforts in superconductivity, with particular emphasis on the related SDIO sponsored program on HTS applications.

  7. US Navy superconductivity program

    NASA Technical Reports Server (NTRS)

    Gubser, Donald U.

    1991-01-01

    Both the new high temperature superconductors (HTS) and the low temperature superconductors (LTS) are important components of the Navy's total plan to integrate superconductivity into field operational systems. Fundamental research is an important component of the total Navy program and focuses on the HTS materials. Power applications (ship propulsion) use LTS materials while space applications (millimeter wave electronics) use HTS materials. The Space Experiment to be conducted at NRL will involve space flight testing of HTS devices built by industry and will demonstrate the ability to engineer and space qualify these devices for systems use. Another important component of the Navy's effort is the development of Superconducting Quantum Interference Device (SQUID) magnetometers. This program will use LTS materials initially, but plans to implement HTS materials as soon as possible. Hybrid HTS/LTS systems are probable in many applications. A review of the status of the Navy's HTS materials research is given as well as an update on the Navy's development efforts in superconductivity.

  8. Navy superconductivity efforts

    NASA Astrophysics Data System (ADS)

    Gubser, D. U.

    1990-04-01

    Both the new high temperature superconductors (HTS) and the low temperature superconductors (LTS) are important components of Navy's total plan to integrate superconductivity into field operational systems. Fundamental research is an important component of the total Navy program and focuses on the HTS materials. Power applications (ship propulsion, etc.) use LTS materials while space applications (MMW electronics, etc.) use HTS materials. The Space Experiment being conducted at NRL will involve space flight testing of HTS devices built by industry and will demonstrate the ability to engineer and space qualify these devices for systems use. Another important component of the Navy's effort is the development of Superconducting Quantum Interference Device (SQUID) magnetometers. This program will use LTS materials initially, but plans to implement HTS materials as soon as possible. Hybrid HTS/LTS systems are probable in many applications. A review of the status of the Navy's HTS materials research is given as well as an update on the Navy's development efforts in superconductivity, with particular emphasis on the related SDIO sponsored program on HTS applications.

  9. Tunable superconducting microstrip resonators

    NASA Astrophysics Data System (ADS)

    Adamyan, A. A.; Kubatkin, S. E.; Danilov, A. V.

    2016-04-01

    We report on a simple yet versatile design for a tunable superconducting microstrip resonator. Niobium nitride is employed as the superconducting material and aluminum oxide, produced by atomic layer deposition, as the dielectric layer. We show that the high quality of the dielectric material allows to reach the internal quality factors in the order of Qi˜104 in the single photon regime. Qi rapidly increases with the number of photons in the resonator N and exceeds 105 for N ˜10 -50 . A straightforward modification of the basic microstrip design allows to pass a current bias through the strip and to control its kinetic inductance. We achieve a frequency tuning δf =62 MHz around f0=2.4 GHz for a fundamental mode and δf =164 MHz for a third harmonic. This translates into a tuning parameter Qiδf /f0=150 . The presented design can be incorporated into essentially any superconducting circuitry operating at temperatures below 2.5 K.

  10. Magnetically leviated superconducting bearing

    DOEpatents

    Weinberger, Bernard R.; Lynds, Jr., Lahmer

    1993-01-01

    A magnetically levitated superconducting bearing includes a magnet (2) mounted on a shaft (12) that is rotatable around an axis of rotation and a Type II superconductor (6) supported on a stator (14) in proximity to the magnet (2). The superconductor (6) is positioned so that when it is cooled to its superconducting state in the presence of a magnetic field, it interacts with the magnet (2) to produce an attractive force that levitates the magnet (2) and supports a load on the shaft (12). The interaction between the superconductor (6) and magnet(2) also produces surface screening currents (8) that generate a repulsive force perpendicular to the load. The bearing also has means for maintaining the superconductor at a temperature below its critical temperature (16, 18). The bearing could also be constructed so the magnet (2) is supported on the stator (14) and the superconductor (6) is mounted on the shaft (12). The bearing can be operated by cooling the superconductor (6) to its superconducting state in the presence of a magnetic field.

  11. Analysis of electric current flow through the HTc multilayered superconductors

    NASA Astrophysics Data System (ADS)

    Sosnowski, J.

    2016-02-01

    Issue of the flow of the transport current through multilayered high-temperature superconductors is considered, depending on the direction of the electric current towards the surface of the superconducting CuO2 layers. For configuration of the current flow inside of the layers and for perpendicular magnetic field, it will be considered the current limitations connected with interaction of pancake type vortices with nano-sized defects, created among other during fast neutrons irradiation. So it makes this issue associated with work of nuclear energy devices, like tokamak ITER, LHC and actually developed accelerator Nuclotron-NICA, as well as cryocables. Phenomenological analysis of the pinning potential barrier formation will be in the paper given, which determines critical current flow inside the plane. Comparison of theoretical model with experimental data will be presented too as well as influence of fast neutrons irradiation dose on critical current calculated. For current direction perpendicular to superconducting planes the current-voltage characteristics are calculated basing on model assuming formation of long intrinsic Josephson's junctions in layered HTc superconductors.

  12. Diffractive coherence in multilayer dielectric gratings

    SciTech Connect

    Shore, B.W.; Feit, M.D.; Perry, M.D.; Boyd, R.D.; Britten, J.A.; Li, Lifeng

    1995-05-26

    Successful operation of large-scale high-power lasers, such as those in use and planned at LLNL and elsewhere, require optical elements that can withstand extremely high fluences without suffering damage. Of particular concern are dielectric diffraction gratings used for beam sampling and pulse compression. Laser induced damage to bulk dielectric material originates with coupling of the electric field of the radiation to bound electrons, proceeding through a succession of mechanisms that couple the electron kinetic energy to lattice energy and ultimately to macroscopic structural changes (e.g. melting). The constructive interference that is responsible for the diffractive behavior of a grating or the reflective properties of a multilayer dielectric stack can enhance the electric field above values that would occur in unstructured homogeneous material. Much work has been done to model damage to bulk matter. The presence of nonuniform electric fields, resulting from diffractive coherence, has the potential to affect damage thresholds and requires more elaborate theory. We shall discuss aspects of work directed towards understanding the influence of dielectric structures upon damage, with particular emphasis on computations and interpretation of electric fields within dielectric gratings and multilayer dielectric stacks, noting particularly the interference effects that occur in these structures.

  13. Superconducting linacs: some recent developments

    SciTech Connect

    Bollinger, L.M.

    1985-01-01

    The paper is a review of superconducting linacs that are of interest for heavy-ion acceleration. Most of the paper is concerned with energy boosters for projectiles from tandem electrostatic accelerators, the only application for which superconducting linacs are now used for heavy-ion acceleration. There is also a brief discussion of the concept of a superconducting injector linac being developed as a replacement of the tandem in a multi-stage acceleration system. Throughout, the emphasis is on the technology of the superconducting linac, including some attention to the relationships between resonator design parameters and accelerator performance characteristics. 21 refs., 14 figs., 3 tabs.

  14. Korea's developmental program for superconductivity

    NASA Technical Reports Server (NTRS)

    Hong, Gye-Won; Won, Dong-Yeon; Kuk, Il-Hyun; Park, Jong-Chul

    1995-01-01

    Superconductivity research in Korea was firstly carried out in the late 70's by a research group in Seoul National University (SNU), who fabricated a small scale superconducting magnetic energy storage system under the financial support from Korea Electric Power Company (KEPCO). But a few researchers were involved in superconductivity research until the oxide high Tc superconductor was discovered by Bednorz and Mueller. After the discovery of YBaCuO superconductor operating above the boiling point of liquid nitrogen (77 K)(exp 2), Korean Ministry of Science and Technology (MOST) sponsored a special fund for the high Tc superconductivity research to universities and national research institutes by recognizing its importance. Scientists engaged in this project organized 'High Temperature Superconductivity Research Association (HITSRA)' for effective conducting of research. Its major functions are to coordinate research activities on high Tc superconductivity and organize the workshop for active exchange of information. During last seven years the major superconductivity research has been carried out through the coordination of HITSRA. The major parts of the Korea's superconductivity research program were related to high temperature superconductor and only a few groups were carrying out research on conventional superconductor technology, and Korea Atomic Energy Research Institute (KAERI) and Korea Electrotechnology Research Institute (KERI) have led this research. In this talk, the current status and future plans of superconductivity research in Korea will be reviewed based on the results presented in interim meeting of HITSRA, April 1-2, 1994. Taejeon, as well as the research activity of KAERI.

  15. Superconductivity-related insulating behavior.

    PubMed

    Sambandamurthy, G; Engel, L W; Johansson, A; Shahar, D

    2004-03-12

    We present the results of an experimental study of superconducting, disordered, thin films of amorphous indium oxide. These films can be driven from the superconducting phase to a reentrant insulating state by the application of a perpendicular magnetic field (B). We find that the high-B insulator exhibits activated transport with a characteristic temperature, TI. TI has a maximum value (TpI) that is close to the superconducting transition temperature (Tc) at B=0, suggesting a possible relation between the conduction mechanisms in the superconducting and insulating phases. Tp(I) and Tc display opposite dependences on the disorder strength.

  16. Topological Superconductivity in Dirac Semimetals.

    PubMed

    Kobayashi, Shingo; Sato, Masatoshi

    2015-10-30

    Dirac semimetals host bulk band-touching Dirac points and a surface Fermi loop. We develop a theory of superconducting Dirac semimetals. Establishing a relation between the Dirac points and the surface Fermi loop, we clarify how the nontrivial topology of Dirac semimetals affects their superconducting state. We note that the unique orbital texture of Dirac points and a structural phase transition of the crystal favor symmetry-protected topological superconductivity with a quartet of surface Majorana fermions. We suggest the possible application of our theory to recently discovered superconducting states in Cd_{3}As_{2}.

  17. Superconducting current in hybrid structures with an antiferromagnetic interlayer

    SciTech Connect

    Zaitsev, A. V. Ovsyannikov, G. A.; Constantinian, K. Y. Kislinskii, Yu. V.; Shadrin, A. V.; Borisenko, I. V.; Komissinskiy, P. V.

    2010-02-15

    It is shown experimentally that the superconducting current density in Nb/Au/Ca{sub 1-x}Sr{sub x}CuO{sub 2}/YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} hybrid superconducting heterostructures with a Ca{sub 1-x}Sr{sub x}CuO{sub 2} anti-ferromagnetic (AF) cuprate interlayer is anomalously high for interlayer thicknesses d{sub M} = 10-50 nm and the characteristic damping length for superconducting correlations is on the order of 10 nm. The experimental results are explained on the basis of theoretical analysis of a junction of two superconductors (S' and S) connected by a magnetic multilayer with the AF ordering of magnetization in the layers. It is shown that with such a magnetization ordering, anomalous proximity effect determined by the singlet component of the condensate wavefunction may take place. As a result, the critical currents in S'/I/AF/S and S'/I/N/S structures (I denotes an insulator, and N, the normal metal) may coincide in order of magnitude even when the thickness of the AF interlayer considerably exceeds the decay length of the condensate wavefunction in ferromagnetic layers.

  18. Noise analysis of DC SQUIDs with damped superconducting flux transformers

    NASA Astrophysics Data System (ADS)

    Faley, M. I.; Poppe, U.; Urban, K.; Fagaly, R. L.

    2010-06-01

    An analysis was performed of intrinsic noise for high-Tc DC SQUID with superconducting flux transformer (FT) containing resistive elements. For a SQUID with a loop inductance of about 40 pH we observed voltage swings of ~55 μV and a flux noise of ~4 μΦ0/√Hz at 77 K. Inductive coupling of an 8-mm multilayer superconducting FT to the SQUID increased voltage swings to ~70 μV due to effective reduction of the SQUID loop inductance. This also increased the flux noise to ~6μΦ0/√Hz, corresponding to a field resolution of ~18 fT/√Hz at 77 K with a white noise spectrum down to frequency ~10 Hz. The main sources of white flux noise were the Nyquist noise in the Josephson junctions and the FT, as well as the suppression of the DC SQUID voltage swings caused by parasitic capacitance between the FT and the SQUID. An ultra-low-ohmic resistor with resistance value between the flux-creep-induced resistances of superconductors (below ~0.1 nΩ) and resistances of conventional resistors (above ~0.1 mΩ) was developed. An RL-circuit based high-pass filter (HPF) with time constant ~7 sec was realized and integrated in the superconducting FT. The contribution of the HPF to the noise of the sensors was measured and compared with calculated values.

  19. Tailoring the magnetoimpedance effect of NiFe/Ag multilayer

    NASA Astrophysics Data System (ADS)

    Corrêa, M. A.; Bohn, F.; Chesman, C.; da Silva, R. B.; Viegas, A. D. C.; Sommer, R. L.

    2010-07-01

    The magnetoimpedance (MI) effect was investigated in NiFe/Ag multilayered (ML) and ML/SiO2/Ag/SiO2/ML structured multilayered (SD) ferromagnetic films grown by magnetron sputtering. The MI measurements were performed with an impedance analyzer over a wide frequency range, from 10 MHz to 1.8 GHz. Sample geometries are mainly responsible for the different MI behaviours and by considering the entire frequency range, distinct mechanisms responsible for MI changes were associated. For the ML sample, a maximum value of 80%, associated with the appearance of ferromagnetic resonance (FMR), was reached at around 1 GHz. For the SD sample, the striking feature is the existence of two distinct frequency ranges with high MI% values of 80% at around 100 MHz, related to the skin and magnetoinductive effects, and of 120% at around 1 GHz, associated with the strong skin and FMR effect.

  20. Superconductivity on the border of weak itinerant ferromagnetism in UCoGe.

    PubMed

    Huy, N T; Gasparini, A; de Nijs, D E; Huang, Y; Klaasse, J C P; Gortenmulder, T; de Visser, A; Hamann, A; Görlach, T; Löhneysen, H V

    2007-08-10

    We report the coexistence of ferromagnetic order and superconductivity in UCoGe at ambient pressure. Magnetization measurements show that UCoGe is a weak ferromagnet with a Curie temperature T(C)=3 K and a small ordered moment m(0)=0.03 micro(B). Superconductivity is observed with a resistive transition temperature T(s)=0.8 K for the best sample. Thermal-expansion and specific-heat measurements provide solid evidence for bulk magnetism and superconductivity. The proximity to a ferromagnetic instability, the defect sensitivity of T(s), and the absence of Pauli limiting, suggest triplet superconductivity mediated by critical ferromagnetic fluctuations.

  1. An outline of positron measurements of superconducting oxides

    SciTech Connect

    Howell, R.H.; Fluss, M.J.

    1991-03-01

    Positron measurements on superconducting oxides have gone through an evolution from divergent results of low statistical precision on samples of suspect quality to convergent results of higher statistical precision on high quality samples. We outline the elements affecting the progress of these experiments and questions that can be addressed at our present state of the art. 11 refs.

  2. Concerning superconducting inertial guidance gyroscopes inside superconducting magnetic shields

    SciTech Connect

    Satterthwaite, J.C.; Gawlinski, E.T.

    1997-12-01

    Superconductors can in theory be used to detect rotation by Josephson interference or by detection of the London field, a magnetic induction that fills the interior of any rotating bulk superconductor. One might hope to use these properties of superconductors to build a practical inertial guidance gyroscope. A problem arises from the necessity of surrounding the device with superconducting magnetic shielding: the London field generated by a co-rotating shield eliminates the response of the superconducting device within the shield. The present article demonstrates this point more rigorously than has been done before, discussing solutions of Ampere`s law for rotating and nonrotating superconductors and paying careful attention to boundary conditions. Beginning with a supercurrent density derivable from either the Ginzburg-Landau or the London theory of superconductivity, the article shows: (1) that a superconducting device cannot distinguish between rotation and an applied magnetic field; (2) that a superconducting device surrounded by a co-rotating superconducting shield cannot detect rotation. The term `superconducting gyroscope` in this article refers only to a device whose working principle is the response of the superconductor itself to rotation, not to any device in which superconducting electronic components are used to detect some other effect. {copyright} {ital 1997 American Institute of Physics.}

  3. Optimization of superconducting tiling pattern for superconducting bearings

    DOEpatents

    Hull, J.R.

    1996-09-17

    An apparatus and method for reducing magnetic field inhomogeneities which produce rotational loss mechanisms in high temperature superconducting magnetic bearings are disclosed. Magnetic field inhomogeneities are reduced by dividing high temperature superconducting structures into smaller structures, and arranging the smaller structures into tiers which stagger the magnetic field maximum locations of the smaller structures. 20 figs.

  4. Optimization of superconducting tiling pattern for superconducting bearings

    DOEpatents

    Hull, John R.

    1996-01-01

    An apparatus and method for reducing magnetic field inhomogeneities which produce rotational loss mechanisms in high temperature superconducting magnetic bearings. Magnetic field inhomogeneities are reduced by dividing high temperature superconducting structures into smaller structures, and arranging the smaller structures into tiers which stagger the magnetic field maximum locations of the smaller structures.

  5. Piezoelectric multilayer actuator life test.

    PubMed

    Sherrit, Stewart; Bao, Xiaoqi; Jones, Christopher M; Aldrich, Jack B; Blodget, Chad J; Moore, James D; Carson, John W; Goullioud, Renaud

    2011-04-01

    Potential NASA optical missions such as the Space Interferometer Mission require actuators for precision positioning to accuracies of the order of nanometers. Commercially available multilayer piezoelectric stack actuators are being considered for driving these precision mirror positioning mechanisms. These mechanisms have potential mission operational requirements that exceed 5 years for one mission life. To test the feasibility of using these commercial actuators for these applications and to determine their reliability and the redundancy requirements, a life test study was undertaken. The nominal actuator requirements for the most critical actuators on the Space Interferometry Mission (SIM) in terms of number of cycles was estimated from the Modulation Optics Mechanism (MOM) and Pathlength control Optics Mechanism (POM) and these requirements were used to define the study. At a nominal drive frequency of 250 Hz, one mission life is calculated to be 40 billion cycles. In this study, a set of commercial PZT stacks configured in a potential flight actuator configuration (pre-stressed to 18 MPa and bonded in flexures) were tested for up to 100 billion cycles. Each test flexure allowed for two sets of primary and redundant stacks to be mechanically connected in series. The tests were controlled using an automated software control and data acquisition system that set up the test parameters and monitored the waveform of the stack electrical current and voltage. The samples were driven between 0 and 20 V at 2000 Hz to accelerate the life test and mimic the voltage amplitude that is expected to be applied to the stacks during operation. During the life test, 10 primary stacks were driven and 10 redundant stacks, mechanically in series with the driven stacks, were open-circuited. The stroke determined from a strain gauge, the temperature and humidity in the chamber, and the temperature of each individual stack were recorded. Other properties of the stacks, including the

  6. NASA/MSFC multilayer diffusion models and computer program for operational prediction of toxic fuel hazards

    NASA Technical Reports Server (NTRS)

    Dumbauld, R. K.; Bjorklund, J. R.; Bowers, J. F.

    1973-01-01

    The NASA/MSFC multilayer diffusion models are discribed which are used in applying meteorological information to the estimation of toxic fuel hazards resulting from the launch of rocket vehicle and from accidental cold spills and leaks of toxic fuels. Background information, definitions of terms, description of the multilayer concept are presented along with formulas for determining the buoyant rise of hot exhaust clouds or plumes from conflagrations, and descriptions of the multilayer diffusion models. A brief description of the computer program is given, and sample problems and their solutions are included. Derivations of the cloud rise formulas, users instructions, and computer program output lists are also included.

  7. Interface-engineered spin-dependent transport in perpendicular Co/Pt multilayers

    NASA Astrophysics Data System (ADS)

    Jiang, Shao-Long; Yang, Guang; Teng, Jiao; Guo, Qi-Xun; Li, Lei-Lei; Yu, Guang-Hua

    2016-11-01

    The improvement of anomalous Hall effect (AHE) has been obtained through the introduction of a Ta metallic layer at the Co/MgO interface in perpendicular [Pt/Co]3/MgO multilayers. It is exhibited that the saturation anomalous Hall resistivity is 42% larger than that in Co/Pt multilayers without Ta insertion. More meaningfully, thermally stable AHE feature is gained in perpendicular [Pt/Co]3/Ta/MgO multilayers despite Co-Pt interdiffusion. The AHE is enhanced for sample [Pt/Co]3/Ta/MgO after annealing, mainly due to the enhancement of the side-jump and intrinsic contributions.

  8. Composite arrays of superconducting microstrip line resonators

    SciTech Connect

    Mohebbi, H. R. Miao, G. X.; Benningshof, O. W. B.; Taminiau, I. A. J.; Cory, D. G.

    2014-03-07

    A novel design of an array of half-wave superconductive microstrip resonators is described. The resonator is intended to be useful for electron spin resonance studies of thin film samples at cryogenic temperatures. It achieves a high quality factor, has a small mode-volume, and creates a uniform magnetic field in a plane above the resonator. The device is made of thin film Niobium on sapphire wafer and is tested with a static magnetic field. Variation of Q-factor versus the magnetic field's strength at different temperatures is reported and is in a good agreement with simulation when the loss due to the vortices is included. Also, the power-dependence response of the resonator is shown in experiments and is verified by capturing the nonlinearity associated with the surface impedance of the superconducting film into the circuit model of the device.

  9. Critical parameters of superconducting materials and structures

    SciTech Connect

    Fluss, M.J.; Howell, R.H.; Sterne, P.A.; Dykes, J.W.; Mosley, W.D.; Chaiken, A.; Ralls, K.; Radousky, H.

    1995-02-01

    We report here the completion of a one year project to investigate the synthesis, electronic structure, defect structure, and physical transport properties of high temperature superconducting oxide materials. During the course of this project we produced some of the finest samples of single crystal detwinned YBa{sub 2}Cu{sub 3}O{sub 7}, and stoichiometrically perfect (Ba,K)BiO{sub 3}. We deduced the Fermi surface of YBa{sub 2}Cu{sub 3}O{sub 7}, (La,Sr){sub 2}CuO{sub 4}, and (Ba,K)BiO{sub 3} through the recording of the electron momentum density in these materials as measured by positron annihilation spectroscopy and angle resolved photoemission. We also performed extensive studies on Pr substituted (Y,Pr)Ba{sub 2}Cu{sub 3}O{sub 7} so as to further understand the origin of the electron pairing leading to superconductivity.

  10. Midwest Superconductivity Consortium: 1995 Progress report

    SciTech Connect

    1996-01-01

    The mission of the Midwest Superconductivity Consortium, MISCON, is to advance the science and understanding of high Tc superconductivity. During the past year, 26 projects produced over 133 talks and 127 publications. Three Master`s Degrees and 9 Doctor`s of Philosophy Degrees were granted to students working on MISCON projects. Group activities and interactions involved 2 MISCON group meetings (held in January and July); the third MISCON Summer School held in July; 12 external speakers; 81 collaborations (with universities, industry, Federal laboratories, and foreign research centers); and 54 exchanges of samples and/or measurements. Research achievements this past year focused on understanding the effects of processing phenomena on structure-property interrelationships and the fundamental nature of transport properties in high-temp superconductors.

  11. Midwest Superconductivity Consortium. Progress report, 1992

    SciTech Connect

    Bement, A.L. Jr.

    1993-01-01

    Mission of the Midwest Superconductivity Consortium, MISCON, is to advance the science and understanding of high Tc superconductivity. Programmatic research focuses upon key materials-related problems; principally, synthesis and processing and properties limiting transport phenomena. During the past year, 26 projects produced over 133 talks and 113 publications. publications. Two Master`s Degrees and one Ph.D. were granted to students working on MISCON projects. Group activities and interactions involved two MISCON group meetings (held in July and January), twenty external speakers, 36 collaborations, 10 exchanges of samples and/or measurements, and one (1) gift of equipment from industry. Research achievements this past year expanded our understanding of processing phenomena on structure property interrelationships and the fundamental nature of transport properties in high-temperature superconductors.

  12. Surface-resistance measurements using superconducting stripline resonators.

    PubMed

    Hafner, Daniel; Dressel, Martin; Scheffler, Marc

    2014-01-01

    We present a method to measure the absolute surface resistance of conductive samples at a set of GHz frequencies with superconducting lead stripline resonators at temperatures 1-6 K. The stripline structure can easily be applied for bulk samples and allows direct calculation of the surface resistance without the requirement of additional calibration measurements or sample reference points. We further describe a correction method to reduce experimental background on high-Q resonance modes by exploiting TEM-properties of the external cabling. We then show applications of this method to the reference materials gold, tantalum, and tin, which include the anomalous skin effect and conventional superconductivity. Furthermore, we extract the complex optical conductivity for an all-lead stripline resonator to find a coherence peak and the superconducting gap of lead.

  13. FeSi diffusion barriers in Fe/FeSi/Si/FeSi/Fe multilayers and oscillatory antiferromagnetic exchange coupling

    NASA Astrophysics Data System (ADS)

    Stromberg, F.; Bedanta, S.; Antoniak, C.; Keune, W.; Wende, H.

    2008-10-01

    We study the diffusion of 57Fe probe atoms in Fe/FeSi/Si/FeSi/Fe multilayers on Si(111) prepared by molecular beam epitaxy by means of 57Fe conversion electron Mössbauer spectroscopy (CEMS). We demonstrate that the application of FeSi boundary layers successfully inhibits the diffusion of 57Fe into the Si layer. The critical thickness for the complete prevention of Fe diffusion takes place at a nominal FeSi thickness of tFeSi = 10-12 Å, which was confirmed by the evolution of the isomer shift δ of the crucial CEM subspectrum. The formation of the slightly defective c-FeSi phase for thicker FeSi boundary layers (~20 Å) was confirmed by CEMS and reflection high-energy electron diffraction (RHEED). Ferromagnetic resonance (FMR) shows that, for tFeSi = 0-14 Å, the Fe layers in all samples are antiferromagnetically coupled and we observe an oscillatory antiferromagnetic coupling strength with FMR and superconducting quantum interference device (SQUID) magnetometry for varying FeSi thickness with a period of ~6 Å.

  14. Superconducting High Resolution Fast-Neutron Spectrometers

    SciTech Connect

    Hau, Ionel Dragos

    2006-01-01

    Superconducting high resolution fast-neutron calorimetric spectrometers based on 6LiF and TiB{sub 2} absorbers have been developed. These novel cryogenic spectrometers measure the temperature rise produced in exothermal (n, α) reactions with fast neutrons in 6Li and 10B-loaded materials with heat capacity C operating at temperatures T close to 0.1 K. Temperature variations on the order of 0.5 mK are measured with a Mo/Cu thin film multilayer operated in the transition region between its superconducting and its normal state. The advantage of calorimetry for high resolution spectroscopy is due to the small phonon excitation energies kBT on the order of μeV that serve as signal carriers, resulting in an energy resolution ΔE ~ (kBT2C)1/2, which can be well below 10 keV. An energy resolution of 5.5 keV has been obtained with a Mo/Cu superconducting sensor and a TiB2 absorber using thermal neutrons from a 252Cf neutron source. This resolution is sufficient to observe the effect of recoil nuclei broadening in neutron spectra, which has been related to the lifetime of the first excited state in 7Li. Fast-neutron spectra obtained with a 6Li-enriched LiF absorber show an energy resolution of 16 keV FWHM, and a response in agreement with the 6Li(n, α)3H reaction cross section and Monte Carlo simulations for energies up to several MeV. The energy resolution of order of a few keV makes this novel instrument applicable to fast-neutron transmission spectroscopy based on the unique elemental signature provided by the neutron absorption and scattering resonances. The optimization of the energy resolution based on analytical and numerical models of the detector response is discussed in the context of these applications.

  15. A Multi-layered target for the Study of Neutron-Unbound Nuclei

    NASA Astrophysics Data System (ADS)

    Gueye, Paul; Frank, Nathan; Thoennessen, Michael

    2013-04-01

    The MoNA/LISA setup at the National Superconducting Cyclotron Laboratory at Michigan State University has provided an avenue to study the nuclear structure of unbound states/nuclei at and beyond the neutron drip line for the past decade using secondary beams from the Coupled Cyclotron Facility. A new multi-layered Si/Be active target is planned to be built to specifically study neutron unbound nuclei. In these experiments the decay energy is reconstructed from fragment-neutron coincidence measurements which are typically low in count rate. The multi-layered target will allow the use of thicker targets to increase the reaction rates, thus enabling to study currently out of reach nuclei such as 21C, 23C, and 24N. A description of the new setup and physics impact will be discussed.

  16. Vortex pinning vs. superconducting wire network in nanostructured superconductors

    NASA Astrophysics Data System (ADS)

    Vicent, Jose L.

    2014-03-01

    Superconducting films with array of ordered defects allow studying effects which are governed by the interplay between lengths of the nanostructured sample and lengths related to physical parameters, as for example coherence length. When the coherence length and the separation between the defects are similar, the sample can mimic a superconducting wire network. In this situation, applied magnetic fields induce Little-Parks oscillations due to fluxoid quantization constraint. These L-P oscillations vanish when the coherence length is smaller than the ``stripe'' superconducting region between the defects. In superconducting films with array of nanodefects periodic oscillations can also be detected in resistance R(H), critical current Ic(H), magnetization M(H) and ac-susceptibility χac(H) in a broader temperature range than the temperature interval where L-P oscillations are present. Vortex pinning mechanisms are the origin of these oscillations. These oscillations emerge due to matching effects between two lattices: the vortex lattice and the lattice of defects. These oscillations are detected in a broader temperature interval than the temperature interval where L-P oscillations are present. Worth to note that, due to the coherence length divergence at Tc, a crossover to wire network behavior is experimentally found always. Interestingly, both mechanisms coexist close to superconducting critical temperatures; i. e. in the temperature region where the sample mimics superconducting wire network. These overlapping effects can be experimentally separated and both origins can be discriminated. We have analyzed and single out, with magnetotransport measurements, both mechanisms: pinning and fluxoid quantization constraint in superconducting films with arrays of non-magnetic and magnetic dots. Work supported by Spanish MINECO and CAM.

  17. Properties of superconducting Bi-Sr-Ca-Cu-O system remelted under higher gravity conditions

    NASA Astrophysics Data System (ADS)

    Volkov, M. P.; Melekh, B. T.; Parfeniev, R. V.; Kartenko, N. F.; Regel, L. L.; Turchaninov, A. M.

    1992-04-01

    The structure and magnetic properties of high Tc superconductor Bi-Sr-Ca-Cu-O samples remelted under 1 g0, 8 g0 and 12 g0 gravity levels have been investigated. Superconducting properties make a change along the ingots. The dependence of structural and superconducting properties on the gravity level and their time degradation have been observed.

  18. Power superconducting power transmission cable

    DOEpatents

    Ashworth, Stephen P.

    2003-06-10

    The present invention is for a compact superconducting power transmission cable operating at distribution level voltages. The superconducting cable is a conductor with a number of tapes assembled into a subconductor. These conductors are then mounted co-planarly in an elongated dielectric to produce a 3-phase cable. The arrangement increases the magnetic field parallel to the tapes thereby reducing ac losses.

  19. Power superconducting power transmission cable

    DOEpatents

    Ashworth, Stephen P.

    2003-01-01

    The present invention is for a compact superconducting power transmission cable operating at distribution level voltages. The superconducting cable is a conductor with a number of tapes assembled into a subconductor. These conductors are then mounted co-planarly in an elongated dielectric to produce a 3-phase cable. The arrangement increases the magnetic field parallel to the tapes thereby reducing ac losses.

  20. High critical current superconducting tapes

    DOEpatents

    Holesinger, Terry G.; Jia, Quanxi; Foltyn, Stephen R.

    2003-09-23

    Improvements in critical current capacity for superconducting film structures are disclosed and include the use of a superconducting RE-BCO layer including a mixture of rare earth metals, e.g., yttrium and europium, where the ratio of yttrium to europium in the RE-BCO layer ranges from about 3 to 1 to from about 1.5 to 1.

  1. Preparation of Mo-Re-C samples containing Mo7Re13C with the β-Mn-type structure by solid state reaction of planetary-ball-milled powder mixtures of Mo, Re and C, and their crystal structures and superconductivity

    NASA Astrophysics Data System (ADS)

    Oh-ishi, Katsuyoshi; Nagumo, Kenta; Tateishi, Kazuya; Takafumi, Ohnishi; Yoshikane, Kenta; Sugiyama, Machiko; Oka, Kengo; Kobayashi, Ryota

    2017-01-01

    Mo-Re-C compounds containing Mo7Re13C with the β-Mn structure were synthesized with high-melting-temperature metals Mo, Re, and C powders using a conventional solid state method with a planetary ball milling machine instead of the arc melting method. Use of the ball milling machine was necessary to obtain Mo7Re13C with the β-Mn structure using the solid state method. Almost single-phase Mo7Re13C with a trace of impurity were obtained using the synthesis method. By XRF and lattice parameter measurements on the samples, Fe element existed in the compound synthesized using the planetary ball milling machine with a pot and balls made of steel, though Fe element was not detected in the compound synthesized using a pot and balls made of tungsten carbide. The former compound containg the Fe atom did not show superconductivity but the latter compound without the Fe atom showed superconductivity at 6.1 K.

  2. Observation of Superconductivity in Tetragonal FeS.

    PubMed

    Lai, Xiaofang; Zhang, Hui; Wang, Yingqi; Wang, Xin; Zhang, Xian; Lin, Jianhua; Huang, Fuqiang

    2015-08-19

    The possibility of superconductivity in tetragonal FeS has attracted considerable interest because of its similarities to the FeSe superconductor. However, all efforts made to pursue superconductivity in tetragonal FeS have failed so far, and it remains controversial whether tetragonal FeS is metallic or semiconducting. Here we report the observation of superconductivity at 5 K in tetragonal FeS that is synthesized by the hydrothermal reaction of iron powder with sulfide solution. The obtained samples are highly crystalline and less air-sensitive, in contrast to those reported in the literature, which are meta-stable and air-sensitive. Magnetic and electrical properties measurements show that the samples behave as a paramagnetic metal in the normal state and exhibit superconductivity below 5 K. The high crystallinity and the stoichiometry of the samples play important roles in the observation of superconductivity. The present results demonstrate that tetragonal FeS is a promising new platform to realize high-temperature superconductors.

  3. A superconducting magnetic gear

    NASA Astrophysics Data System (ADS)

    Campbell, A. M.

    2016-05-01

    A comparison is made between a magnetic gear using permanent magnets and superconductors. The objective is to see if there are any fundamental reasons why superconducting magnets should not provide higher power densities than permanent magnets. The gear is based on the variable permeability design of Attilah and Howe (2001 IEEE Trans. Magn. 37 2844-46) in which a ring of permanent magnets surrounding a ring of permeable pole pieces with a different spacing gives an internal field component at the beat frequency. Superconductors can provide much larger fields and forces but will saturate the pole pieces. However the gear mechanism still operates, but in a different way. The magnetisation of the pole pieces is now constant but rotates with angle at the beat frequency. The result is a cylindrical Halbach array which produces an internal field with the same symmetry as in the linear regime, but has an analytic solution. In this paper a typical gear system is analysed with finite elements using FlexPDE. It is shown that the gear can work well into the saturation regime and that the Halbach array gives a good approximation to the results. Replacing the permanent magnets with superconducting tapes can give large increases in torque density, and for something like a wind turbine a combined gear and generator is possible. However there are major practical problems. Perhaps the most fundamental is the large high frequency field which is inevitably present and which will cause AC losses. Also large magnetic fields are required, with all the practical problems of high field superconducting magnets in rotating machines. Nevertheless there are ways of mitigating these difficulties and it seems worthwhile to explore the possibilities of this technology further.

  4. Theory of RF superconductivity for resonant cavities

    NASA Astrophysics Data System (ADS)

    Gurevich, Alex

    2017-03-01

    An overview of a theory of electromagnetic response of superconductors in strong radio-frequency (RF) electromagnetic fields is given with the emphasis on applications to superconducting resonant cavities for particle accelerators. The paper addresses fundamentals of the BCS surface resistance, the effect of subgap states and trapped vortices on the residual surface resistance at low RF fields, and a nonlinear surface resistance at strong fields, particularly the effect of the RF field suppression of the surface resistance. These issues are essential for the understanding of the field dependence of high quality factors Q({B}a)∼ {10}10{--}{10}11 achieved on the Nb cavities at 1.3–2 K in strong RF fields B a close to the depairing limit, and the extended Q({B}a) rise which has been observed on Ti and N-treated Nb cavities. Possible ways of further increase of Q({B}a) and the breakdown field by optimizing impurity concentration at the surface and by multilayer nanostructuring with materials other than Nb are discussed.

  5. Electric Field Induced Superconductivity in Layered Materials

    NASA Astrophysics Data System (ADS)

    Ye, J. T.; Craciun, M. F.; Russo, S.; Morpurgo, M. F.; Kasahara, Y.; Yuan, H. T.; Shimotani, H.; Iwasa, Y.

    2011-03-01

    Using electric double layer (EDL) gating, large amount of carriers can be accumulated on a broad range of materials, which provides new opportunities in effectively manipulating their electronic properties in complementary with the chemical doping. In searching for novel transport phenomena, layered materials are advantageous because atomically flat surface can be easily fabricated using the graphene techniques. We used layered material: ZrNCl and graphite to act as the channel of EDL transistors. For both ZrNCl and graphene, we achieved high carrier density up to 1014 cm-2 , electrostatically. For graphene, we studied the high carrier density transport for graphene of 1-3 layers. Transport properties at the high carrier density exhibit clear layer dependence governed by the intrinsic band structures of graphene and its multi-layers. For ZrNCl EDL transistor, we observed metallic states at gate voltage higher than 3.5 V followed by gate-induced superconductivity after metal-insulator transition when the transistor was cooled down to about 15 K.

  6. Spin Pumping in Ferromagnetic Multilayers

    NASA Astrophysics Data System (ADS)

    Taniguchi, Tomohiro; Imamura, Hiroshi

    We present a brief review of our recent study on spin pumping in ferromagnetic multilayers. First, we present theoretical models describing spin pumping induced by ferromagnetic resonance (FMR). Then we apply the spin-pumping theory to FMR in ferromagnetic multilayers and show that the line width of the FMR spectrum depends on the thickness of the ferromagnetic metal layer which is not in resonance. We also show that the penetration depths of transverse spin current in ferromagnetic metals can be determined by analyzing the line width of the FMR spectrum. The obtained penetration depths of the transverse spin current were 3.7 nm for Py, 2.5 nm for CoFe, 12.0 nm for CoFeB, and 1.7 nm for Co, respectively.

  7. Anomalous magnetoresistance in Fibonacci multilayers.

    SciTech Connect

    Machado, L. D.; Bezerra, C. G.; Correa, M. A.; Chesman, C.; Pearson, J. E.; Hoffmann, A.

    2012-01-01

    We theoretically investigated magnetoresistance curves in quasiperiodic magnetic multilayers for two different growth directions, namely, [110] and [100]. We considered identical ferromagnetic layers separated by nonmagnetic layers with two different thicknesses chosen based on the Fibonacci sequence. Using parameters for Fe/Cr multilayers, four terms were included in our description of the magnetic energy: Zeeman, cubic anisotropy, bilinear coupling, and biquadratic coupling. The minimum energy was determined by the gradient method and the equilibrium magnetization directions found were used to calculate magnetoresistance curves. By choosing spacers with a thickness such that biquadratic coupling is stronger than bilinear coupling, unusual behaviors for the magnetoresistance were observed: (i) for the [110] case, there is a different behavior for structures based on even and odd Fibonacci generations, and, more interesting, (ii) for the [100] case, we found magnetic field ranges for which the magnetoresistance increases with magnetic field.

  8. Superconductivity in a chiral nanotube

    NASA Astrophysics Data System (ADS)

    Qin, F.; Shi, W.; Ideue, T.; Yoshida, M.; Zak, A.; Tenne, R.; Kikitsu, T.; Inoue, D.; Hashizume, D.; Iwasa, Y.

    2017-02-01

    Chirality of materials are known to affect optical, magnetic and electric properties, causing a variety of nontrivial phenomena such as circular dichiroism for chiral molecules, magnetic Skyrmions in chiral magnets and nonreciprocal carrier transport in chiral conductors. On the other hand, effect of chirality on superconducting transport has not been known. Here we report the nonreciprocity of superconductivity--unambiguous evidence of superconductivity reflecting chiral structure in which the forward and backward supercurrent flows are not equivalent because of inversion symmetry breaking. Such superconductivity is realized via ionic gating in individual chiral nanotubes of tungsten disulfide. The nonreciprocal signal is significantly enhanced in the superconducting state, being associated with unprecedented quantum Little-Parks oscillations originating from the interference of supercurrent along the circumference of the nanotube. The present results indicate that the nonreciprocity is a viable approach toward the superconductors with chiral or noncentrosymmetric structures.

  9. Superconductivity in a chiral nanotube.

    PubMed

    Qin, F; Shi, W; Ideue, T; Yoshida, M; Zak, A; Tenne, R; Kikitsu, T; Inoue, D; Hashizume, D; Iwasa, Y

    2017-02-16

    Chirality of materials are known to affect optical, magnetic and electric properties, causing a variety of nontrivial phenomena such as circular dichiroism for chiral molecules, magnetic Skyrmions in chiral magnets and nonreciprocal carrier transport in chiral conductors. On the other hand, effect of chirality on superconducting transport has not been known. Here we report the nonreciprocity of superconductivity-unambiguous evidence of superconductivity reflecting chiral structure in which the forward and backward supercurrent flows are not equivalent because of inversion symmetry breaking. Such superconductivity is realized via ionic gating in individual chiral nanotubes of tungsten disulfide. The nonreciprocal signal is significantly enhanced in the superconducting state, being associated with unprecedented quantum Little-Parks oscillations originating from the interference of supercurrent along the circumference of the nanotube. The present results indicate that the nonreciprocity is a viable approach toward the superconductors with chiral or noncentrosymmetric structures.

  10. High-temperature conventional superconductivity

    NASA Astrophysics Data System (ADS)

    Eremets, M. I.; Drozdov, A. P.

    2017-02-01

    Conventional superconductors are described well by the Bardeen – Cooper – Schrieffer (BCS) theory (1957) and its related theories, all of which importantly put no explicit limit on transition temperature Tc. While this allows, in principle, room-temperature superconductivity, no such phenomenon has been observed. Since the discovery of superconductivity in 1911, the measured critical temperature of BCS superconductors has not until recently exceeded 39 K. In 2014, hydrogen sulfide under high pressure was experimentally found to exhibit superconductivity at Tc = 200 K, a record high value which greatly exceeds that of the previous class of high-temperature superconductors, the cuprates. The superconductivity mechanism in cuprates has not yet been explained. Over a period of 25 years, the critical temperature of cuprates has not been increased above 164 K. The paper reviews research on record-high Tc superconductivity in hydrogen sulphide and other hydrides. Prospects for increasing Tc to room temperature are also discussed.

  11. High-temperature conventional superconductivity

    NASA Astrophysics Data System (ADS)

    Eremets, M. I.; Drozdov, A. P.

    2016-11-01

    Conventional superconductors are described well by the Bardeen - Cooper - Schrieffer (BCS) theory (1957) and its related theories, all of which importantly put no explicit limit on transition temperature T_c. While this allows, in principle, room-temperature superconductivity, no such phenomenon has been observed. Since the discovery of superconductivity in 1911, the measured critical temperature of BCS superconductors has not until recently exceeded 39 K. In 2014, hydrogen sulfide under high pressure was experimentally found to exhibit superconductivity at T_c=200 K, a record high value which greatly exceeds that of the previous class of high-temperature superconductors, the cuprates. The superconductivity mechanism in cuprates has not yet been explained. Over a period of 25 years, the critical temperature of cuprates has not been increased above 164 K. The paper reviews research on record-high T_c superconductivity in hydrogen sulphide and other hydrides. Prospects for increasing T_c to room temperature are also discussed.

  12. TOPICAL REVIEW: Superconducting bearings

    NASA Astrophysics Data System (ADS)

    Hull, John R.

    2000-02-01

    The physics and technology of superconducting bearings is reviewed. Particular attention is given to the use of high-temperature superconductors (HTSs) in rotating bearings. The basic phenomenology of levitational forces is presented, followed by a brief discussion of the theoretical models that can be used for conceptual understanding and calculations. The merits of various HTS bearing designs are presented, and the behaviour of HTS bearings in typical situations is discussed. The article concludes with a brief survey of various proposed applications for HTS bearings.

  13. Superconducting magnet cooling system

    DOEpatents

    Vander Arend, Peter C.; Fowler, William B.

    1977-01-01

    A device is provided for cooling a conductor to the superconducting state. The conductor is positioned within an inner conduit through which is flowing a supercooled liquid coolant in physical contact with the conductor. The inner conduit is positioned within an outer conduit so that an annular open space is formed therebetween. Through the annular space is flowing coolant in the boiling liquid state. Heat generated by the conductor is transferred by convection within the supercooled liquid coolant to the inner wall of the inner conduit and then is removed by the boiling liquid coolant, making the heat removal from the conductor relatively independent of conductor length.

  14. Superconducting dipole electromagnet

    DOEpatents

    Purcell, John R.

    1977-07-26

    A dipole electromagnet of especial use for bending beams in particle accelerators is wound to have high uniformity of magnetic field across a cross section and to decrease evenly to zero as the ends of the electromagnet are approached by disposing the superconducting filaments of the coil in the crescent-shaped nonoverlapping portions of two intersecting circles. Uniform decrease at the ends is achieved by causing the circles to overlap increasingly in the direction of the ends of the coil until the overlap is complete and the coil is terminated.

  15. Superconductivity in plutonium compounds

    NASA Astrophysics Data System (ADS)

    Sarrao, J. L.; Bauer, E. D.; Mitchell, J. N.; Tobash, P. H.; Thompson, J. D.

    2015-07-01

    Although the family of plutonium-based superconductors is relatively small, consisting of four compounds all of which crystallize in the tetragonal HoCoGa5 structure, these materials serve as an important bridge between the known Ce- and U-based heavy fermion superconductors and the high-temperature cuprate superconductors. Further, the partial localization of 5f electrons that characterizes the novel electronic properties of elemental plutonium appears to be central to the relatively high superconducting transition temperatures that are observed in PuCoGa5, PuRhGa5, PuCoIn5, and PuRhIn5.

  16. Unusual nature of ferromagnetism coexisting with superconductivity in UGe2.

    PubMed

    Nishioka, T; Motoyama, G; Nakamura, S; Kadoya, H; Sato, N K

    2002-06-10

    We report the discovery of a jump in the magnetization of a macroscopic single crystalline sample of UGe2 that shows coexistence of ferromagnetism and superconductivity. In particular, we observe that the jump occurs at regular intervals of field and only at very low temperatures. This novel feature implies that the magnetic field induces a sudden change of the direction of the magnetization between two equivalent easy axes of magnetization even in a macroscopic sample. We ascribe it to a field-tuned resonant tunneling between quantum spin states, and we propose that the size of a magnetic domain is smaller than a superconducting coherence length.

  17. Casting Of Multilayer Ceramic Tapes

    NASA Technical Reports Server (NTRS)

    Collins, Earl R., Jr.

    1991-01-01

    Procedure for casting thin, multilayer ceramic membranes, commonly called tapes, involves centrifugal casting at accelerations of 1,800 to 2,000 times normal gravitational acceleration. Layers of tape cast one at a time on top of any previous layer or layers. Each layer cast from slurry of ground ceramic suspended in mixture of solvents, binders, and other components. Used in capacitors, fuel cells, and electrolytic separation of oxygen from air.

  18. Electrodeposited Multilayer Solar Cell Materials^*

    NASA Astrophysics Data System (ADS)

    Friedfeld, R.; Raffaelle, R. P.; Mantovani, J. G.

    1996-03-01

    We have been investigating the synthesis of electrochemically deposited multilayer structures based on the Cu_xIn_2-xSe2 system for use in thin film solar cells. Electrochemical deposition is a cost- effective alternative for producing these solar cell materials. Cu_xIn_2-xSe2 is one of the most promising thin film solar cell materials, due to its ideal optical and electrical properties. The interest in multilayer structures is due to their proposed use in increasing thin film solar cell efficiency. We present our attempts at synthesizing nanoscale multilayer thin films based on the Cu_xIn_2-xSe2 system using various solutions and techniques. We have characterized the composition, structure, and optical properties of these films using energy dispersive spectroscopy, x-ray diffraction, scanning tunneling microscopy, and optical spectroscopy. * This work was supported by the Southeastern University Research Association in collaboration with Oak Ridge National Laboratory and the Florida Solar Energy Center.

  19. Ultra-thin multilayer capacitors.

    SciTech Connect

    Renk, Timothy Jerome; Monson, Todd C.

    2009-06-01

    The fabrication of ultra-thin lanthanum-doped lead zirconium titanate (PLZT) multilayer ceramic capacitors (MLCCs) using a high-power pulsed ion beam was studied. The deposition experiments were conducted on the RHEPP-1 facility at Sandia National Laboratories. The goal of this work was to increase the energy density of ceramic capacitors through the formation of a multilayer device with excellent materials properties, dielectric constant, and standoff voltage. For successful device construction, there are a number of challenging requirements including achieving correct stoichiometric and crystallographic composition of the deposited PLZT, as well as the creation of a defect free homogenous film. This report details some success in satisfying these requirements, although 900 C temperatures were necessary for PLZT perovskite phase formation. These temperatures were applied to a previously deposited multi-layer film which was then post-annealed to this temperature. The film exhibited mechanical distress attributable to differences in the coefficient of thermal expansion (CTE) of the various layers. This caused significant defects in the deposited films that led to shorts across devices. A follow-on single layer deposition without post-anneal produced smooth layers with good interface behavior, but without the perovskite phase formation. These issues will need to be addressed in order for ion beam deposited MLCCs to become a viable technology. It is possible that future in-situ heating during deposition may address both the CTE issue, and result in lowered processing temperatures, which in turn could raise the probability of successful MLCC formation.

  20. Superconducting Bolometer Array Architectures

    NASA Technical Reports Server (NTRS)

    Benford, Dominic; Chervenak, Jay; Irwin, Kent; Moseley, S. Harvey; Shafer, Rick; Staguhn, Johannes; Wollack, Ed; Oegerle, William (Technical Monitor)

    2002-01-01

    The next generation of far-infrared and submillimeter instruments require large arrays of detectors containing thousands of elements. These arrays will necessarily be multiplexed, and superconducting bolometer arrays are the most promising present prospect for these detectors. We discuss our current research into superconducting bolometer array technologies, which has recently resulted in the first multiplexed detections of submillimeter light and the first multiplexed astronomical observations. Prototype arrays containing 512 pixels are in production using the Pop-Up Detector (PUD) architecture, which can be extended easily to 1000 pixel arrays. Planar arrays of close-packed bolometers are being developed for the GBT (Green Bank Telescope) and for future space missions. For certain applications, such as a slewed far-infrared sky survey, feedhorncoupling of a large sparsely-filled array of bolometers is desirable, and is being developed using photolithographic feedhorn arrays. Individual detectors have achieved a Noise Equivalent Power (NEP) of -10(exp 17) W/square root of Hz at 300mK, but several orders of magnitude improvement are required and can be reached with existing technology. The testing of such ultralow-background detectors will prove difficult, as this requires optical loading of below IfW. Antenna-coupled bolometer designs have advantages for large format array designs at low powers due to their mode selectivity.

  1. Driven superconducting quantum circuits

    NASA Astrophysics Data System (ADS)

    Nakamura, Yasunobu

    2014-03-01

    Driven nonlinear quantum systems show rich phenomena in various fields of physics. Among them, superconducting quantum circuits have very attractive features such as well-controlled quantum states with design flexibility, strong nonlinearity of Josephson junctions, strong coupling to electromagnetic driving fields, little internal dissipation, and tailored coupling to the electromagnetic environment. We have investigated properties and functionalities of driven superconducting quantum circuits. A transmon qubit coupled to a transmission line shows nearly perfect spatial mode matching between the incident and scattered microwave field in the 1D mode. Dressed states under a driving field are studied there and also in a semi-infinite 1D mode terminated by a resonator containing a flux qubit. An effective Λ-type three-level system is realized under an appropriate driving condition. It allows ``impedance-matched'' perfect absorption of incident probe photons and down conversion into another frequency mode. Finally, the weak signal from the qubit is read out using a Josephson parametric amplifier/oscillator which is another nonlinear circuit driven by a strong pump field. This work was partly supported by the Funding Program for World-Leading Innovative R&D on Science and Technology (FIRST), Project for Developing Innovation Systems of MEXT, MEXT KAKENHI ``Quantum Cybernetics,'' and the NICT Commissioned Research.

  2. Superconducting linear actuator

    NASA Technical Reports Server (NTRS)

    Johnson, Bruce; Hockney, Richard

    1993-01-01

    Special actuators are needed to control the orientation of large structures in space-based precision pointing systems. Electromagnetic actuators that presently exist are too large in size and their bandwidth is too low. Hydraulic fluid actuation also presents problems for many space-based applications. Hydraulic oil can escape in space and contaminate the environment around the spacecraft. A research study was performed that selected an electrically-powered linear actuator that can be used to control the orientation of a large pointed structure. This research surveyed available products, analyzed the capabilities of conventional linear actuators, and designed a first-cut candidate superconducting linear actuator. The study first examined theoretical capabilities of electrical actuators and determined their problems with respect to the application and then determined if any presently available actuators or any modifications to available actuator designs would meet the required performance. The best actuator was then selected based on available design, modified design, or new design for this application. The last task was to proceed with a conceptual design. No commercially-available linear actuator or modification capable of meeting the specifications was found. A conventional moving-coil dc linear actuator would meet the specification, but the back-iron for this actuator would weigh approximately 12,000 lbs. A superconducting field coil, however, eliminates the need for back iron, resulting in an actuator weight of approximately 1000 lbs.

  3. Magnetic Field Reentrant Superconductivity in Aluminum Nanowires

    NASA Astrophysics Data System (ADS)

    Bretz-Sullivan, Terence; Goldman, Allen

    Reentrance to the superconducting state through the application of a magnetic field to quasi-one dimensional superconductors driven resistive by current, is counter to the expected properties of superconductors. It was not until recently that a microscopic mechanism explaining the phenomenon was proposed in which superconductivity and phase slip driven dissipation coexist in a non-equilibrium state. Here we present additional results of magnetic field induced reentrance into the superconducting state in quasi-one-dimensional aluminum nanowires with an in-plane magnetic field both transverse to, and along the wire axis. The reentrant behavior is seen in the magnetic field dependence of the I-V characteristic and resistance vs. temperature, and in the wire's magnetoresistance at 450mK. This work was supported by DOE Basic Energy Sciences Grant DE-FG02-02ER46004. Samples were fabricated at the Minnesota Nanofabrication Center. Parts of this work were carried out in the University of Minnesota Characterization Facility, a member of the Materials Research Facilities Network (www.mrfn.org) funded via the NSF MRSEC program.

  4. Multilayer Radar Absorbing Non-Woven Material

    NASA Astrophysics Data System (ADS)

    Dedov, A. V.; Nazarov, V. G.

    2016-06-01

    We study the electrical properties of multilayer radar absorbing materials obtained by adding nonwoven sheets of dielectric fibers with an intermediate layer of electrically conductive carbon fibers. Multilayer materials that absorb electromagnetic radiation in a wide frequency range are obtained by varying the content of the carbon fibers. The carbon-fiber content dependent mechanism of absorption of electromagnetic radiation by sheets and multilayer materials is considered.

  5. Multi-layer seal for electrochemical devices

    DOEpatents

    Chou, Yeong-Shyung [Richland, WA; Meinhardt, Kerry D [Kennewick, WA; Stevenson, Jeffry W [Richland, WA

    2010-11-16

    Multi-layer seals are provided that find advantageous use for reducing leakage of gases between adjacent components of electrochemical devices. Multi-layer seals of the invention include a gasket body defining first and second opposing surfaces and a compliant interlayer positioned adjacent each of the first and second surfaces. Also provided are methods for making and using the multi-layer seals, and electrochemical devices including said seals.

  6. Multi-layer seal for electrochemical devices

    DOEpatents

    Chou, Yeong-Shyung [Richland, WA; Meinhardt, Kerry D [Kennewick, WA; Stevenson, Jeffry W [Richland, WA

    2010-09-14

    Multi-layer seals are provided that find advantageous use for reducing leakage of gases between adjacent components of electrochemical devices. Multi-layer seals of the invention include a gasket body defining first and second opposing surfaces and a compliant interlayer positioned adjacent each of the first and second surfaces. Also provided are methods for making and using the multi-layer seals, and electrochemical devices including said seals.

  7. Quantum Hall effect in graphene decorated with disordered multilayer patches

    SciTech Connect

    Nam, Youngwoo; Sun, Jie Lindvall, Niclas; Kireev, Dmitry; Yurgens, August; Jae Yang, Seung; Rae Park, Chong; Woo Park, Yung

    2013-12-02

    Quantum Hall effect (QHE) is observed in graphene grown by chemical vapour deposition using platinum catalyst. The QHE is even seen in samples which are irregularly decorated with disordered multilayer graphene patches and have very low mobility (<500 cm{sup 2}V{sup −1}s{sup −1}). The effect does not seem to depend on electronic mobility and uniformity of the resulting material, which indicates the robustness of QHE in graphene.

  8. Analysis of Multilayered Printed Circuit Boards using Computed Tomography

    DTIC Science & Technology

    2014-05-01

    of failed boards. This report presents the results of computerised tomography on multilayered Printed Circuit Boards using a SkyScan 1076 ...including any internal layers of a PCB. In this report we describe examples of the use of a SkyScan 1076 X-ray CT system as a non-destructive...problematic when scanning larger PCBs. Although the maximum PCB size for the SkyScan 1076 was 65 mm x 400 mm the range of samples used allowed a

  9. Heat transport in self-pumping multilayer insulation

    NASA Astrophysics Data System (ADS)

    Hałaczek, T. L.; Rafałowicz, J.

    The results of thermal conductivity measurements of a self-pumping multilayer insulation are reported. Spacers of the tested samples of self-pumping insulation were loaded with different amounts of sorbents. The tests were carried out in a flat-plate calorimeter at boundary temperatures of 90 and 295 K. A conventional form of insulation was also tested. A comparison is made with results obtained using an unguarded calorimeter.

  10. A multilayer groundwater sampler for characterizing contaminant plumes

    SciTech Connect

    Kaplan, E.; Heiser, J.

    1992-12-18

    This final report describes activities related to the design and initial demonstration of a passive multilayer groundwater sampling system. The apparatus consists of remotely controlled cylinders filled with deionized water which are connected in tandem. Vertical fine structure of contaminants are easily defined. Using the apparatus in several wells may lead to three dimensional depictions of groundwater contamination, thereby providing the information necessary for site characterization and remediation.

  11. A multilayer groundwater sampler for characterizing contaminant plumes. Final report

    SciTech Connect

    Kaplan, E.; Heiser, J.

    1992-12-18

    This final report describes activities related to the design and initial demonstration of a passive multilayer groundwater sampling system. The apparatus consists of remotely controlled cylinders filled with deionized water which are connected in tandem. Vertical fine structure of contaminants are easily defined. Using the apparatus in several wells may lead to three dimensional depictions of groundwater contamination, thereby providing the information necessary for site characterization and remediation.

  12. ESR study of superconducting K-doped C 60 "polymer"

    NASA Astrophysics Data System (ADS)

    Kinoshita, N.; Grigoryan, L. S.; Kinoshita, T.; Tokumoto, M.

    1997-03-01

    ESR measurements of the superconducting K-doped C 60 "polymer" were carried out, in order to clarify the difference from ordinary K-doped C 60, i.e. monomer. Observed ESR spectrum was simulated by four Lorentzian lines. The temperature dependences of the ESR linewidth, g factor and spin susceptibility are obtained for each ESR line. At room temperature the linewidth and g factor of the broadest ESR absorption line are, about 400 G and 2.01, respectively. The linewidths for other lines are 150, 53 and 16 G with the common g factor of 2.000. The linewidths of the ESR spectrum of superconducting K-doped C 60 "polymer" are found to be much broader than those of monomer sample. Similar to monomer sample, two absorption lines with weakly temperature-dependent intensity were observed, one of which disappeared (150 G width) below the super-conducting transition temperature ( Tc = 15 K).

  13. Observation of superconductivity in hydrogen sulfide from nuclear resonant scattering.

    PubMed

    Troyan, Ivan; Gavriliuk, Alexander; Rüffer, Rudolf; Chumakov, Alexander; Mironovich, Anna; Lyubutin, Igor; Perekalin, Dmitry; Drozdov, Alexander P; Eremets, Mikhail I

    2016-03-18

    High-temperature superconductivity remains a focus of experimental and theoretical research. Hydrogen sulfide (H2S) has been reported to be superconducting at high pressures and with a high transition temperature. We report on the direct observation of the expulsion of the magnetic field in H2S compressed to 153 gigapascals. A thin (119)Sn film placed inside the H2S sample was used as a sensor of the magnetic field. The magnetic field on the (119)Sn sensor was monitored by nuclear resonance scattering of synchrotron radiation. Our results demonstrate that an external static magnetic field of about 0.7 tesla is expelled from the volume of (119)Sn foil as a result of the shielding by the H2S sample at temperatures between 4.7 K and approximately 140 K, revealing a superconducting state of H2S.

  14. A chemically stable PVD multilayer encapsulation for lithium microbatteries

    NASA Astrophysics Data System (ADS)

    Ribeiro, J. F.; Sousa, R.; Cunha, D. J.; Vieira, E. M. F.; Silva, M. M.; Dupont, L.; Goncalves, L. M.

    2015-10-01

    A multilayer physical vapour deposition (PVD) thin-film encapsulation method for lithium microbatteries is presented. Lithium microbatteries with a lithium cobalt oxide (LiCoO2) cathode, a lithium phosphorous oxynitride (LiPON) electrolyte and a metallic lithium anode are under development, using PVD deposition techniques. Metallic lithium film is still the most common anode on this battery technology; however, it presents a huge challenge in terms of material encapsulation (lithium reacts with almost any materials deposited on top and almost instantly begins oxidizing in contact with atmosphere). To prove the encapsulation concept and perform all the experiments, lithium films were deposited by thermal evaporation technique on top of a glass substrate, with previously patterned Al/Ti contacts. Three distinct materials, in a multilayer combination, were tested to prevent lithium from reacting with protection materials and atmosphere. These multilayer films were deposited by RF sputtering and were composed of lithium phosphorous oxide (LiPO), LiPON and silicon nitride (Si3N4). To complete the long-term encapsulation after breaking the vacuum, an epoxy was applied on top of the PVD multilayer. In order to evaluate oxidation state of lithium films, the lithium resistance was measured in a four probe setup (cancelling wires/contact resistances) and resistivity calculated, considering physical dimensions. A lithium resistivity of 0.16 Ω μm was maintained for more than a week. This PVD multilayer exonerates the use of chemical vapour deposition (CVD), glove-box chambers and sample manipulation between them, significantly reducing the fabrication cost, since battery and its encapsulation are fabricated in the same PVD chamber.

  15. Superconductivity in just four pairs of (BETS)2GaCl4 molecules.

    PubMed

    Clark, K; Hassanien, A; Khan, S; Braun, K-F; Tanaka, H; Hla, S-W

    2010-04-01

    How small can a sample of superconducting material be and still display superconductivity? This question is relevant to our fundamental understanding of superconductivity, and also to applications in nanoscale electronics, because Joule heating of interconnecting wires is a major problem in nanoscale devices. It has been shown that ultrathin layers of metal can display superconductivity, but any limits on the size of superconducting systems remain a mystery. (BETS)2GaCl4, where BETS is bis(ethylenedithio)tetraselenafulvalene, is an organic superconductor, and in bulk it has a superconducting transition temperature Tc of approximately 8 K and a two-dimensional layered structure that is reminiscent of the high-Tc cuprate superconductors. Here, we use scanning tunnelling spectroscopy to show that a single layer of (BETS)2GaCl4 molecules on an Ag(111) surface displays a superconducting gap that increases exponentially with the length of the molecular chain. Moreover, we show that a superconducting gap can still be detected for just four pairs of (BETS)2GaCl4 molecules. Real-space spectroscopic images directly visualize the chains of BETS molecules as the origin of the superconductivity.

  16. Superconducting properties in tantalum decorated three-dimensional graphene and carbon structures

    SciTech Connect

    Cobaleda, Cayetano S. F. E-mail: wpan@sandia.gov; Xiao, Xiaoyin; Burckel, D. Bruce; Polsky, Ronen; Pan, W. E-mail: wpan@sandia.gov; Huang, Duanni; Diez, Enrique

    2014-08-04

    We present here the results on superconducting properties in tantalum thin films (100 nm thick) deposited on three-dimensional graphene (3DG) and carbon structures. A superconducting transition is observed in both composite thin films with a superconducting transition temperature of 1.2 K and 1.0 K, respectively. We have further measured the magnetoresistance at various temperatures and differential resistance dV/dI at different magnetic fields in these two composite thin films. In both samples, a much large critical magnetic field (∼2 T) is observed and this critical magnetic field shows linear temperature dependence. Finally, an anomalously large cooling effect was observed in the differential resistance measurements in our 3DG-tantalum device when the sample turns superconducting. Our results may have important implications in flexible superconducting electronic device applications.

  17. Spin-orbit-coupled superconductivity.

    PubMed

    Lo, Shun-Tsung; Lin, Shih-Wei; Wang, Yi-Ting; Lin, Sheng-Di; Liang, C-T

    2014-06-25

    Superconductivity and spin-orbit (SO) interaction have been two separate emerging fields until very recently that the correlation between them seemed to be observed. However, previous experiments concerning SO coupling are performed far beyond the superconducting state and thus a direct demonstration of how SO coupling affects superconductivity remains elusive. Here we investigate the SO coupling in the critical region of superconducting transition on Al nanofilms, in which the strength of disorder and spin relaxation by SO coupling are changed by varying the film thickness. At temperatures T sufficiently above the superconducting critical temperature T(c), clear signature of SO coupling reveals itself in showing a magneto-resistivity peak. When T < T(c), the resistivity peak can still be observed; however, its line-shape is now affected by the onset of the quasi two-dimensional superconductivity. By studying such magneto-resistivity peaks under different strength of spin relaxation, we highlight the important effects of SO interaction on superconductivity.

  18. Multilayer porous UHMWPE scaffolds for bone defects replacement.

    PubMed

    Maksimkin, A V; Senatov, F S; Anisimova, N Yu; Kiselevskiy, M V; Zalepugin, D Yu; Chernyshova, I V; Tilkunova, N A; Kaloshkin, S D

    2017-04-01

    Reconstruction of the structural integrity of the damaged bone tissue is an urgent problem. UHMWPE may be potentially used for the manufacture of porous implants simulating as closely as possible the porous cancellous bone tissue. But the extremely high molecular weight of the polymer does not allow using traditional methods of foaming. Porous and multilayer UHMWPE scaffolds with nonporous bulk layer and porous layer that mimics cancellous bone architecture were obtained by solid-state mixing, thermopressing and washing in subcritical water. Structural and mechanical properties of the samples were studied. Porous UHMWPE samples were also studied in vitro and in vivo. The pores of UHMWPE scaffold are open and interconnected. Volume porosity of the obtained samples was 79±2%; the pore size range was 80-700μm. Strong connection of the two layers in multilayer UHMWPE scaffolds was observed with decreased number of fusion defects. Functionality of implants based on multilayer UHMWPE scaffolds is provided by the fixation of scaffolds in the bone defect through ingrowths of the connective tissue into the pores, which ensures the maintenance of the animals' mobility.

  19. Evidence for Intertwining of Superconductivity and Antiferromagnetism in a Cuprate

    NASA Astrophysics Data System (ADS)

    Tranquada, John; Xu, Zhijun; Stock, C.; Chi, S. X.; Kolesnikov, A. I.; Xu, G. Y.; Gu, G. D.

    2014-03-01

    We have used inelastic neutron scattering to measure the low-energy, incommensurate antiferromagnetic spin excitations both above and below the superconducting transition temperature (Tc = 32 K) of La1.905Ba0.095CuO4. While the magnetic excitations in optimally-doped cuprates typically show the development of a spin gap and magnetic resonance below Tc, our sample shows no such effect. Instead strong, gapless spin excitations coexist with bulk superconductivity. To understand this, we note that previous transport measurements have shown that the superconducting layers are decoupled by a magnetic field applied along the c-axis, resulting in a state with frustrated interlayer Josephson coupling, similar to LBCO with x = 1 / 8 , where it has been proposed that pair-density-wave superconductivity occurs. This suggests that, in a similar fashion, the spatially modulated antiferromagnetic correlations (which we see directly in the x = 0 . 095 sample) are intertwined with a spatially modulated superconducting pair wave function. Work at BNL supported by Office of Basic Energy Sciences, US DOE, under Contract No. DE-AC02-98CH10886.

  20. Operational Merits of Maritime Superconductivity

    NASA Astrophysics Data System (ADS)

    Ross, R.; Bosklopper, J. J.; van der Meij, K. H.

    The perspective of superconductivity to transfer currents without loss is very appealing in high power applications. In the maritime sector many machines and systems exist in the roughly 1-100 MW range and the losses are well over 50%, which calls for dramatic efficiency improvements. This paper reports on three studies that aimed at the perspectives of superconductivity in the maritime sector. It is important to realize that the introduction of superconductivity comprises two technology transitions namely firstly electrification i.e. the transition from mechanical drives to electric drives and secondly the transition from normal to superconductive electrical machinery. It is concluded that superconductivity does reduce losses, but its impact on the total energy chain is of little significance compared to the investments and the risk of introducing a very promising but as yet not proven technology in the harsh maritime environment. The main reason of the little impact is that the largest losses are imposed on the system by the fossil fueled generators as prime movers that generate the electricity through mechanical torque. Unless electric power is supplied by an efficient and reliable technology that does not involve mechanical torque with the present losses both normal as well as superconductive electrification of the propulsion will hardly improve energy efficiency or may even reduce it. One exception may be the application of degaussing coils. Still appealing merits of superconductivity do exist, but they are rather related to the behavior of superconductive machines and strong magnetic fields and consequently reduction in volume and mass of machinery or (sometimes radically) better performance. The merits are rather convenience, design flexibility as well as novel applications and capabilities which together yield more adequate systems. These may yield lower operational costs in the long run, but at present the added value of superconductivity rather seems more

  1. Superconducting interfaces between insulating oxides.

    PubMed

    Reyren, N; Thiel, S; Caviglia, A D; Kourkoutis, L Fitting; Hammerl, G; Richter, C; Schneider, C W; Kopp, T; Rüetschi, A-S; Jaccard, D; Gabay, M; Muller, D A; Triscone, J-M; Mannhart, J

    2007-08-31

    At interfaces between complex oxides, electronic systems with unusual electronic properties can be generated. We report on superconductivity in the electron gas formed at the interface between two insulating dielectric perovskite oxides, LaAlO3 and SrTiO3. The behavior of the electron gas is that of a two-dimensional superconductor, confined to a thin sheet at the interface. The superconducting transition temperature of congruent with 200 millikelvin provides a strict upper limit to the thickness of the superconducting layer of congruent with 10 nanometers.

  2. Antiferromagnetic hedgehogs with superconducting cores

    SciTech Connect

    Goldbart, P.M.; Sheehy, D.E.

    1998-09-01

    Excitations of the antiferromagnetic state that resemble antiferromagnetic hedgehogs at large distances but are predominantly superconducting inside a core region are discussed within the context of Zhang{close_quote}s SO(5)-symmetry-based approach to the physics of high-temperature superconducting materials. Nonsingular, in contrast with their hedgehog cousins in pure antiferromagnetism, these texture excitations are what hedgehogs become when the antiferromagnetic order parameter is permitted to {open_quotes}escape{close_quotes} into superconducting directions. The structure of such excitations is determined in a simple setting, and a number of their experimental implications are examined. {copyright} {ital 1998} {ital The American Physical Society}

  3. Antiferromagnetic hedgehogs with superconducting cores

    NASA Astrophysics Data System (ADS)

    Goldbart, Paul M.; Sheehy, Daniel E.

    1998-09-01

    Excitations of the antiferromagnetic state that resemble antiferromagnetic hedgehogs at large distances but are predominantly superconducting inside a core region are discussed within the context of Zhang's SO(5)-symmetry-based approach to the physics of high-temperature superconducting materials. Nonsingular, in contrast with their hedgehog cousins in pure antiferromagnetism, these texture excitations are what hedgehogs become when the antiferromagnetic order parameter is permitted to ``escape'' into superconducting directions. The structure of such excitations is determined in a simple setting, and a number of their experimental implications are examined.

  4. Nozzle for superconducting fiber production

    DOEpatents

    Righi, Jamal

    1992-11-17

    A nozzle apparatus for producing flexible fibers of superconducting material receives melted material from a crucible for containing a charge of the superconducting material. The material is melted in the crucible and falls in a stream through a bottom hole in the crucible. The stream falls through a protecting collar which maintains the stream at high temperatures. The stream is then supplied through the downwardly directed nozzle where it is subjected to a high velocity air flow which breaks the melted superconducting material into ligaments which solidify into the flexible fibers. The fibers are collected by blowing them against a porous cloth.

  5. Mechanical properties of Cu/Ta multilayers prepared by magnetron sputtering

    SciTech Connect

    Nguyen, T.D.; Barbee, T.W., Jr.

    1998-04-01

    The microstructure and mechanical properties of sputtered Cu/Ta multilayers were studied. X- ray diffraction and transmission electron microscopy characterization indicate that both the Ta and Cu in the 2 nm period multilayer are predominantly amorphous, while in longer period samples, the layers are crystalline, with the metastable tetragonal {beta}-Ta observed. No observable microstructure changes upon annealing at 300{degrees}C were found. An average Vickers micro- hardness value of about 5.5 GPa was measured, which increases about 5% upon annealing at 300{degrees}C. Residual stress in the multilayers and its dependence on thermal annealing are reported. The relationships between microstructure and mechanical properties in the multilayers are discussed.

  6. An in situ electron microscopy technique for the study of thermally activated reactions in multilayered materials

    SciTech Connect

    Wall, M.A.; Barbee, T.W. Jr.; Weihs, T.P.

    1995-04-14

    A novel in situ transmission electron microscopy technique for the observation of reaction processes in multilayered materials is reported. The technique involves constant heating rate experiments of multilayered materials in image and diffraction modes. Because the fine scale microstructure of multilayered materials is typically a small fraction of the TEM specimen thickness, realistic comparison of the microstructural evolution with that of similarly processed thick foil samples is possible. Such experiments, when well designed, can provide rapid characterization of phase transformations and stability of nano-structured materials. The results of these experiments can be recorded in both video and micrograph format. The results and limitations of this technique will be shown for the Al/Zr and Al/Monel multilayered systems.

  7. Superconducting electromagnetic thruster

    SciTech Connect

    Meng, J.

    1993-02-11

    An electromagnetic thruster for marine vehicles using a jet of water driven by the interaction of a mutually perpendicular intensified magnetic field and an intensified electric field is disclosed. The intensified magnetic field is produced by superconducting coils cooled by a coolant such as liquid helium. An intensified electric field is produced by passing high amperage current across the seawater jet. These interacting fields produce a Lorentz force perpendicular to mutually perpendicular electric and magnetic field vectors which is used to drive the seawater jet. In some embodiments, the force may also be used to draw water into the jet from the boundary layer flow around the vehicle thereby reducing boundary layer turbulence and associated radiated noise.

  8. Super-Hard Superconductivity

    NASA Astrophysics Data System (ADS)

    Adams, Philip; Prozorov, Ruslan

    2005-03-01

    We present the magnetic response of Type-II superconductivity in the extreme pinning limit, where screening currents within an order of magnitude of the Ginzburg-Landau depairing critical current density develop upon the application of a magnetic field. We show that this ``super-hard'' limit is well approximated in highly disordered, cold drawn, Nb wire whose magnetization response is characterized by a cascade of Meissner-like phases, each terminated by a catastrophic collapse of the magnetization. Direct magneto-optic measurements of the flux penetration depth in the virgin magnetization branch are in excellent agreement with the exponential model in which Jc(B)=Jco(-B/Bo), where Jco˜5x10^6 A/cm^2 for Nb. The implications for the fundamental limiting hardness of a superconductor will be discussed.

  9. Superconducting magnetic coil

    DOEpatents

    Aized, Dawood; Schwall, Robert E.

    1996-06-11

    A superconducting magnetic coil includes a plurality of sections positioned axially along the longitudinal axis of the coil, each section being formed of an anisotropic high temperature superconductor material wound about a longitudinal axis of the coil and having an associated critical current value that is dependent on the orientation of the magnetic field of the coil. The cross section of the superconductor, or the type of superconductor material, at sections along the axial and radial axes of the coil are changed to provide an increased critical current at those regions where the magnetic field is oriented more perpendicularly to the conductor plane, to thereby increase the critical current at these regions and to maintain an overall higher critical current of the coil.

  10. Superconducting magnetic coil

    DOEpatents

    Aized, D.; Schwall, R.E.

    1999-06-22

    A superconducting magnetic coil includes a plurality of sections positioned axially along the longitudinal axis of the coil, each section being formed of an anisotropic high temperature superconductor material wound about a longitudinal axis of the coil and having an associated critical current value that is dependent on the orientation of the magnetic field of the coil. The cross section of the superconductor, or the type of superconductor material, at sections along the axial and radial axes of the coil are changed to provide an increased critical current at those regions where the magnetic field is oriented more perpendicularly to the conductor plane, to thereby increase the critical current at these regions and to maintain an overall higher critical current of the coil. 15 figs.

  11. Superconducting magnetic coil

    DOEpatents

    Aized, Dawood; Schwall, Robert E.

    1999-06-22

    A superconducting magnetic coil includes a plurality of sections positioned axially along the longitudinal axis of the coil, each section being formed of an anisotropic high temperature superconductor material wound about a longitudinal axis of the coil and having an associated critical current value that is dependent on the orientation of the magnetic field of the coil. The cross section of the superconductor, or the type of superconductor material, at sections along the axial and radial axes of the coil are changed to provide an increased critical current at those regions where the magnetic field is oriented more perpendicularly to the conductor plane, to thereby increase the critical current at these regions and to maintain an overall higher critical current of the coil.

  12. Superconducting magnetic energy storage

    SciTech Connect

    Hassenzahl, W.

    1988-08-01

    Recent programmatic developments in Superconducting Magnetic Energy Storage (SMES) have prompted renewed and widespread interest in this field. In mid 1987 the Defense Nuclear Agency, acting for the Strategic Defense Initiative Office, issued a request for proposals for the design and construction of SMES Engineering Test Model (ETM). Two teams, one led by Bechtel and the other by Ebasco, are now engaged in the first phase of the development of a 10 to 20 MWhr ETM. This report presents the rationale for energy storage on utility systems, describes the general technology of SMES, and explains the chronological development of the technology. The present ETM program is outlined; details of the two projects for ETM development are described in other papers in these proceedings. The impact of high T/sub c/ materials on SMES is discussed. 69 refs., 3 figs., 3 tabs.

  13. Superconductivity in Cuprate Superlattices

    NASA Astrophysics Data System (ADS)

    Bozovic, Ivan; Eckstein, J. N.

    The following sections are included: * Introduction * YBCO/DBCO superlattices: the commencement * YBCO/PBCO superlattices: conjectures * Bi-2212:2201 superlattices: Q2D superconductivity * YBCO/(Pr,Y,Ca)BCO superlattices: clarification * More Bi-2212 superlattices: afterthoughts * Positive proximity effect in Dy-doped 2212 * Long-range proximity effect in 2201 * HTS in one-unit-cell thick 2212 layer * Inelastic hopping via localized states * Materials and layering * Integrity of ultrathin layers * Thickness dependence of the barrier resistance * Temperature dependence of the barrier resistance * Voltage dependence of current through the barrier * Interpretation: multiple inelastic hopping * Negative proximity effect on 2212 * Interlayer coupling in HTS superlattices: conclusions * The science and technology of HTS superlattices * Vortex dynamics * Critical current scaling law * Thermal activation of vortex motion * Superlattice phonons * Atomic-layer engineering of artificial HTS materials * Technological applications of HTS superlattices * Summary * Intercell coupling in HTS superlattices * Vortex dynamics * Phonon spectra * Atomic-layer engineering of artificial HTS materials * Applications * Acknowledgments * References

  14. Negative refraction and superconductivity

    NASA Astrophysics Data System (ADS)

    Amariti, Antonio; Forcella, Davide; Mariotti, Alberto; Siani, Massimo

    2011-10-01

    We discuss exotic properties of charged hydrodynamical systems, in the broken superconducting phase, probed by electromagnetic waves. Motivated by general arguments from hydrodynamics, we observe that negative refraction, namely the propagation in opposite directions of the phase velocities and of the energy flux, is expected for low enough frequencies. We corroborate this general idea by analyzing a holographic superconductor in the AdS/CFT correspondence, where the response functions can be explicitly computed. We study the dual gravitational theory both in the probe and in the backreacted case. We find that, while in the first case the refractive index is positive at every frequency, in the second case there is negative refraction at low enough frequencies. This is in agreement with hydrodynamic considerations.

  15. Superconducting energy storage

    SciTech Connect

    Giese, R.F.

    1993-10-01

    This report describes the status of energy storage involving superconductors and assesses what impact the recently discovered ceramic superconductors may have on the design of these devices. Our description is intended for R&D managers in government, electric utilities, firms, and national laboratories who wish an overview of what has been done and what remains to be done. It is assumed that the reader is acquainted with superconductivity, but not an expert on the topics discussed here. Indeed, it is the author`s aim to enable the reader to better understand the experts who may ask for the reader`s attention, support, or funding. This report may also inform scientists and engineers who, though expert in related areas, wish to have an introduction to our topic.

  16. Anyon Superconductivity of Sb

    NASA Astrophysics Data System (ADS)

    Maksoed, Wh-; Parengkuan, August

    2016-10-01

    In any permutatives to Pedro P. Kuczhynski from Peru, for anyon superconductivity sought EZ Kuchinskii et al.: ``Anion height dependence of Tc & d.o.s of Fe-based Superconductors'', 2010 as well as ``on the basis of electron microscopy & AFM measurements, these phenomena are quantified with focus on fractal dimension, particle perimeter & size of the side branch(tip width) in bert Stegemann et al.:Crystallization of Sb nanoparticles-Pattern Formation & Fractal Growth'', J.PhysChem B., 2004. For dendritic & dendrimer fractal characters shown further: ``antimony denrites were found to be composed of well-crystallized nanoflakes with size 20-4 nm''- Bou Zhau, et al., MaterialLetters, 59 (2005). The alkyl triisopropyl attached in TIPSb those includes in DNA, haemoglobin membrane/fixed-bed reactor for instance quotes in Dragony Fu, Nature Review Cancer, 12 (Feb 2012). Heartfelt Gratitudes to HE. Mr. Prof. Ir. Handojo.

  17. Superconducting combined function magnets

    SciTech Connect

    Hahn, H.; Fernow, R.C.

    1983-01-01

    Superconducting accelerators and storage rings, presently under construction or in the design phase, are based on separate dipole and quadrupole magnets. It is here suggested that a hybrid lattice configuration consisting of dipoles and combined function gradient magnets would: (1) reduce the number of magnet units and their total cost; and (2) increase the filling factor and thus the energy at a given field. Coil cross sections are presented for the example of the Brookhaven Colliding Beam Accelerator. An asymmetric two-layer cable gradient magnet would have transfer functions of 10.42 G/A and 0.628 G cm/sup -1//A versus 15.77 G/A and 2.03 G cm/sup -1//A of the present separate dipoles and quadrupoles.

  18. Project X superconducting spoke resonator test cryostat 2 K conversion

    NASA Astrophysics Data System (ADS)

    Chen, M.; Dalesandro, A.; Hansen, B.; Klebaner, A.; Nicol, T.; Orlov, Y.; Peterson, T.

    2014-01-01

    Superconducting spoke resonators (SSR1 and SSR2) envisioned for Project X will be developed in Fermilab and operated at temperatures down to 2 K in continuous wave (CW) mode. Each spoke cavity will be tested individually in a cryostat that replicates conditions in the longer multi-cavity cryomodules. This test cryostat has all the features of the longer cryomodules - magnetic shielding, 80 K thermal shield, multi-layer insulation, support post, and input coupler [1]. Fermilab is in the processing of retrofitting the existing test cryostat which was originally designed for operation at 4.5 K. This paper describes the design of the conversion of the current test cryostat, flexible transfer lines, helium relief system and cryogenics interface.

  19. REAL-WORLD SORTING OF RHIC SUPERCONDUCTING MAGNETS.

    SciTech Connect

    WEI,J.; GUPTA,R.; HARRISON,M.; JAIN,A.; PEGGS,S.; THOMPSON,P.; TRBOJEVIC,D.; WANDERER,P.

    1999-03-29

    During the seven-year construction of the Relativistic Heavy Ion Collider (RHIC), more than 1700 superconducting dipoles, quadrupoles, sextupoles, and multi-layer correctors have been constructed and installed. These magnets have been sorted at several production stages to optimize their performance and reliability. For arc magnets, priorities have been put first on quench performance and operational risk minimization, second on field transfer function and other first-order quantities, and finally on nonlinear field errors which were painstakingly optimized at design. For Interaction-Region (IR) magnets, sorting is applied to select the best possible combination of magnets for the low-{beta}* interaction points (IP). This paper summarizes the history of this real-world sorting process.

  20. Multilayer material characterization using thermographic signal reconstruction

    NASA Astrophysics Data System (ADS)

    Shepard, Steven M.; Beemer, Maria Frendberg

    2016-02-01

    Active-thermography has become a well-established Nondestructive Testing (NDT) method for detection of subsurface flaws. In its simplest form, flaw detection is based on visual identification of contrast between a flaw and local intact regions in an IR image sequence of the surface temperature as the sample responds to thermal stimulation. However, additional information and insight can be obtained from the sequence, even in the absence of a flaw, through analysis of the logarithmic derivatives of individual pixel time histories using the Thermographic Signal Reconstruction (TSR) method. For example, the response of a flaw-free multilayer sample to thermal stimulation can be viewed as a simple transition between the responses of infinitely thick samples of the individual constituent layers over the lifetime of the thermal diffusion process. The transition is represented compactly and uniquely by the logarithmic derivatives, based on the ratio of thermal effusivities of the layers. A spectrum of derivative responses relative to thermal effusivity ratios allows prediction of the time scale and detectability of the interface, and measurement of the thermophysical properties of one layer if the properties of the other are known. A similar transition between steady diffusion states occurs for flat bottom holes, based on the hole aspect ratio.

  1. Vortices in magnetically coupled superconducting layered systems

    SciTech Connect

    Mints, Roman G.; Kogan, Vladimir G.; Clem, John R.

    2000-01-01

    Pancake vortices in stacks of thin superconducting films or layers are considered. It is stressed that in the absence of Josephson coupling topological restrictions upon possible configurations of vortices are removed and various examples of structures forbidden in bulk superconductors are given. In particular, it is shown that vortices may skip surface layers in samples of less than a certain size R{sub c} which might be macroscopic. The Josephson coupling suppresses R{sub c} estimates. (c) 2000 The American Physical Society.

  2. Nanoscale constrictions in superconducting coplanar waveguide resonators

    SciTech Connect

    Jenkins, Mark David; Naether, Uta; Ciria, Miguel; Zueco, David; Luis, Fernando; Sesé, Javier; Atkinson, James; Barco, Enrique del; Sánchez-Azqueta, Carlos; Majer, Johannes

    2014-10-20

    We report on the design, fabrication, and characterization of superconducting coplanar waveguide resonators with nanoscopic constrictions. By reducing the size of the center line down to 50 nm, the radio frequency currents are concentrated and the magnetic field in its vicinity is increased. The device characteristics are only slightly modified by the constrictions, with changes in resonance frequency lower than 1% and internal quality factors of the same order of magnitude as the original ones. These devices could enable the achievement of higher couplings to small magnetic samples or even to single molecular spins and have applications in circuit quantum electrodynamics, quantum computing, and electron paramagnetic resonance.

  3. Superconductivity in a chiral nanotube

    PubMed Central

    Qin, F.; Shi, W.; Ideue, T.; Yoshida, M.; Zak, A.; Tenne, R.; Kikitsu, T.; Inoue, D.; Hashizume, D.; Iwasa, Y.

    2017-01-01

    Chirality of materials are known to affect optical, magnetic and electric properties, causing a variety of nontrivial phenomena such as circular dichiroism for chiral molecules, magnetic Skyrmions in chiral magnets and nonreciprocal carrier transport in chiral conductors. On the other hand, effect of chirality on superconducting transport has not been known. Here we report the nonreciprocity of superconductivity—unambiguous evidence of superconductivity reflecting chiral structure in which the forward and backward supercurrent flows are not equivalent because of inversion symmetry breaking. Such superconductivity is realized via ionic gating in individual chiral nanotubes of tungsten disulfide. The nonreciprocal signal is significantly enhanced in the superconducting state, being associated with unprecedented quantum Little-Parks oscillations originating from the interference of supercurrent along the circumference of the nanotube. The present results indicate that the nonreciprocity is a viable approach toward the superconductors with chiral or noncentrosymmetric structures. PMID:28205518

  4. Superconductivity from Emerging Magnetic Moments.

    PubMed

    Hoshino, Shintaro; Werner, Philipp

    2015-12-11

    Multiorbital Hubbard models are shown to exhibit a spatially isotropic spin-triplet superconducting phase, where equal-spin electrons in different local orbitals are paired. This superconducting state is stabilized in the spin-freezing crossover regime, where local moments emerge in the metal phase, and the pairing is substantially assisted by spin anisotropy. The phase diagram features a superconducting dome below a non-Fermi-liquid metallic region and next to a magnetically ordered phase. We suggest that this type of fluctuating-moment-induced superconductivity, which is not originating from fluctuations near a quantum critical point, may be realized in spin-triplet superconductors such as strontium ruthenates and uranium compounds.

  5. Cryogenic Systems and Superconductive Power

    DTIC Science & Technology

    The report defines, investigates, and experimentally evaluates the key elements of a representative crogenic turborefrigerator subsystem suitable for providing reliable long-lived cryogenic refrigeration for a superconductive ship propulsion system.

  6. Mixed-mu superconducting bearings

    DOEpatents

    Hull, John R.; Mulcahy, Thomas M.

    1998-01-01

    A mixed-mu superconducting bearing including a ferrite structure disposed for rotation adjacent a stationary superconductor material structure and a stationary permanent magnet structure. The ferrite structure is levitated by said stationary permanent magnet structure.

  7. Mixed-mu superconducting bearings

    DOEpatents

    Hull, J.R.; Mulcahy, T.M.

    1998-03-03

    A mixed-mu superconducting bearing is disclosed including a ferrite structure disposed for rotation adjacent a stationary superconductor material structure and a stationary permanent magnet structure. The ferrite structure is levitated by said stationary permanent magnet structure. 9 figs.

  8. Superconductivity: A celebration of pairs

    NASA Astrophysics Data System (ADS)

    Norman, Michael R.

    2007-12-01

    It is fifty years since John Bardeen, Leon Cooper and Bob Schrieffer presented the microscopic theory of superconductivity. At a wonderful conference in Urbana the 'good old days' were remembered, and the challenges ahead surveyed.

  9. Method of making coherent multilayer crystals

    DOEpatents

    Schuller, Ivan K.; Falco, Charles M.

    1984-01-01

    A new material consisting of a coherent multilayer crystal of two or more elements where each layer is composed of a single element. Each layer may vary in thickness from about 2 .ANG. to 2500 .ANG.. The multilayer crystals are prepared by sputter deposition under conditions which slow the sputtered atoms to near substrate temperatures before they contact the substrate.

  10. Coherent multilayer crystals and method of making

    DOEpatents

    Schuller, I.K.; Falco, C.M.

    1980-10-30

    A new material is described consisting of a coherent multilayer crystal of two or more elements where each layer is composed of a single element. Each layer may vary in thickness from about 2 A to 2500 A. The multilayer crystals are prepared by sputter deposition under conditions which slow the sputtered atoms to near substrate temperatures before they contact the substrate.

  11. Multi-Layer E-Textile Circuits

    NASA Technical Reports Server (NTRS)

    Dunne, Lucy E.; Bibeau, Kaila; Mulligan, Lucie; Frith, Ashton; Simon, Cory

    2012-01-01

    Stitched e-textile circuits facilitate wearable, flexible, comfortable wearable technology. However, while stitched methods of e-textile circuits are common, multi-layer circuit creation remains a challenge. Here, we present methods of stitched multi-layer circuit creation using accessible tools and techniques.

  12. Developments of high- Tc superconducting current feeders for a large-scale superconducting coil system

    NASA Astrophysics Data System (ADS)

    Mito, T.; Maehata, K.; Mizokami, M.; Ishibashi, K.; Takeo, M.; Iwamoto, A.; Hirano, N.; Shintomi, T.; Kimura, K.; Sawamura, M.; Yamada, S.; Satoh, S.; Motojima, O.

    1998-10-01

    A large-scale superconducting coil system, which is an essential technology for a fusion reactor, requires large capacity and high performance current feeders from the power supplies at the room temperature to the superconducting coils at the operating temperature, which is usually liquid helium temperature at present. The superconducting current feeders are being considered as a promising application of a high temperature superconductor (HTS), which can satisfy the requirements of a large current capacity and a low heat in-leak, simultaneously. To study the feasibility of the HTS current feeders, a melt-textured YBCO bulk superconductor was selected as a candidate material because of its high current transport characteristics. The YBCO disk fabricated by quench and melt growth process was cut into a short sample with the cross section of 7 mm × 7 mm and the length of 40 mm and was mounted on the copper bars to perform the actual large current transport tests. The sample could be successfully excited up to 20 kA at 4.2 K and 10 kA at 77 K. These performance test results and the further R&D items for the HTS current feeders are discussed.

  13. The role of symmetry-breaking-induced interface anisotropy in [Fe/Pt]{sub n} multilayer films

    SciTech Connect

    Li Zhenghua; Xie Hailong; Liu Xi; Bai Jianmin; Wei Fulin; Wei Dan; Yoshimura, S.; Saito, H.; Liu Xiaoxi

    2011-04-01

    The FePt films were deposited with [Fe/Pt]{sub n} multilayer structure on preheated Corning 1737F glass substrate using pure Fe and Pt target in a CMS-18 sputtering system. The dependence of FePt's texture and magnetic properties on the multilayer structure was investigated. The XRD patterns indicate that (111) texture is dominant for all [Fe/Pt]{sub n} (n = 8, 16, 20, 32) multilayer films. However, the measured M-H loops show that the perpendicular anisotropy is greatly enhanced in samples with n = 16, 20, and 32. The origin of the increased perpendicular anisotropy of [Fe/Pt]{sub n} multilayer films is related to the contributions of the interfaces, which will be analyzed using the micromagnetic models, with careful discussions of the crystalline and interface anisotropies. Finally, it is confirmed that the Fe/Pt interfaces favor the perpendicular orientation in the multilayer structure.

  14. Transition-Metal Oxide Superconductivity

    DTIC Science & Technology

    1988-04-20

    pyramidally coordinated complexes of the 02"- deficient compounds, and (iii) that ordering of the sources that produce the mixed-valence Cu2+ɛ+) ions in...With the strong antiferromagnetic exchange coupling of the Fe2+(3+) pairs in ferrites , no superconducting cells should be anticipated and only normal...I couplings dictate significant antiferromagnetic ordering and little chance of superconductivity. This group includes the common ferrite conduction

  15. Hermetically sealed superconducting magnet motor

    DOEpatents

    DeVault, R.C.; McConnell, B.W.; Phillips, B.A.

    1996-07-02

    A hermetically sealed superconducting magnet motor includes a rotor separated from a stator by either a radial gap, an axial gap, or a combined axial and radial gap. Dual conically shaped stators are used in one embodiment to levitate a disc-shaped rotor made of superconducting material within a conduit for moving cryogenic fluid. As the rotor is caused to rotate when the field stator is energized, the fluid is pumped through the conduit. 6 figs.

  16. Hermetically sealed superconducting magnet motor

    DOEpatents

    DeVault, Robert C.; McConnell, Benjamin W.; Phillips, Benjamin A.

    1996-01-01

    A hermetically sealed superconducting magnet motor includes a rotor separated from a stator by either a radial gap, an axial gap, or a combined axial and radial gap. Dual conically shaped stators are used in one embodiment to levitate a disc-shaped rotor made of superconducting material within a conduit for moving cryogenic fluid. As the rotor is caused to rotate when the field stator is energized, the fluid is pumped through the conduit.

  17. Y-Ba Superconducting Ceramics

    NASA Astrophysics Data System (ADS)

    Shunbao, Tian; Xiaofei, Li; Tinglian, Wen; Zuxiang, Lin; Shichun, Li; Huijun, Yu

    Polycrystalline Y-Ba-Cu-O superconducting materials have been studied. It was found that chemical composition and processing condition may play an important role in the final structure and superconducting properties. The density has been determined and compared with the calculated value according to the structure model reported by Bell Labs. The grain size and the morphology of the materials were observed by SEM.

  18. Development of Concepts in Superconductivity

    NASA Astrophysics Data System (ADS)

    Bardeen, John

    This is an excerpt from a talk that John Bardeen gave on the development of the theory of superconductivity in London, England on September 17, 1962 when he received the Fritz London award for his work developing the BCS theory of superconductivity. The talk was given at the Eighth International Conference on Low Temperature Physics at Queen Mary College in London and was reprinted in Physics Today in January of 1963.

  19. Modulated magnetization depth profile in dipolarly coupled magnetic multilayers

    SciTech Connect

    Bedanta, S.; Petracic, O.; Kleemann, W.; Kentzinger, E.; Ruecker, U.; Brueckel, Th.; Paul, A.; Cardoso, S.; Freitas, P. P.

    2006-08-01

    Polarized neutron reflectivity (PNR) and magnetometry studies have been performed on the metal-insulator multilayer [Co{sub 80}Fe{sub 20}(1.6 nm)/Al{sub 2}O{sub 3}(3 nm)]{sub 9} which exhibits dominant dipolar coupling between the ferromagnetic layers. Our PNR measurements at the coercive field reveal a novel and unexpected magnetization state of the sample, exhibiting an oscillating magnetization depth profile from CoFe layer to CoFe layer with a period of five bilayers along the multilayer stack. With the help of micromagnetic simulations we demonstrate that competition between long- and short-ranged dipolar interactions apparently gives rise to this unprecedented phenomenon.

  20. The relation between ferroelasticity and superconductivity

    NASA Technical Reports Server (NTRS)

    Molak, A.; Manka, R.

    1990-01-01

    The high-temperature superconductivity is explained widely by the layered crystal structure. The one- and two-dimensional subsystems and their interaction are investigated here. It is assumed that the high-T(sub c) superconductivity takes place in the two-dimensional subsystem and the increase of the phase transition temperature from 60 K up to 90 K is the consequence of turning on the influence of one-dimensional chains. The interaction between the two subsystems is transferred along the c axis by the phonons of breathing mode, which causes the hybridization of the electronic bonds between these subsystems. The experimental works indicate that the existence of both the chains Cu(1)-O and their interaction with the superconducting plane of Cu(2)-O modify the temperature of the transition to the superconducting state. It is seen from the neutron scattering data that the rates of the interatomic distance dependencies on temperature are changed around 140 K and 90 K. The 'zig-zag' order in Cu(1)-O chains has been postulated but, on the other hand, the vibrations with a large amplitude only were reported. The bi-stabilized situation of the oxygen ions can be caused by the change of distance between these ions and the Ba ions. It leads to the appearance of a two-well potential. Its parameters depend on temperature and the dynamics of the oxygen ions' movement. They can induce the antipolar order, which can be, however, more or less chaotic. The investigation of the ferroelastic properties of Y-Ba-Cu-O samples lead to the conclusion that they are related to jumps of ions inside the given chain and not to a diffusion between different sites in the ab plane. Researchers deduce thus that the fluctuating oxygen ions from these chains create dipoles in the ab plane. They can be described with the pseudo-spin formalism/ - Pauli matrices/. The system can be described with the Ising model. The pseudo-spins interact with phonons and influence the superconductivity in the second

  1. The relation between ferroelasticity and superconductivity

    NASA Technical Reports Server (NTRS)

    Molak, A.; Manka, R.

    1991-01-01

    The high-temperature superconductivity is explained widely by the layered crystal structure. The one- and two-dimensional subsystems and their interaction are investigated here. It is assumed that the high-T(sub c) superconductivity takes place in the two-dimensional subsystem and the increase of the phase transition temperature from 60 K up to 90 K is the consequence of turning on the influence of one-dimensional chains. The interaction between the two subsystems is transferred along the c axis by the phonons of breathing mode, which causes the hybridization of the electronic bonds between these subsystems. The experimental works indicate that the existence of both the chains Cu(1)-O and their interaction with the superconducting plane of Cu(2)-O modify the temperature of the transition to the superconducting state. It is seen from the neutron scattering data that the rates of the interatomic distance dependencies on temperature are changed around 240 K and 90 K. The 'zig-zag' order in Cu(1)-O chains has been postulated but, on the other hand, the vibrations with a large amplitude only were reported. The bi-stabilized situation of the oxygen ions can be caused by the change of distance between these ions and the Ba ions. It leads to the appearance of a two-well potential. Its parameters depend on temperature and the dynamics of the oxygen ions' movement. They can induce the antipolar order, which can be, however, more or less chaotic. The investigation of the ferroelastic properties of Y-Ba-Cu-O samples lead to the conclusion that they are related to jumps of ions inside the given chain and not to a diffusion between different sites in the ab plane. Researchers deduce, thus, that the fluctuating oxygen ions from these chains create dipoles in the ab plane. They can be described with the pseudo-spin formalism (- Pauli matrices). The system can be described with the Ising model. The pseudo-spins interact with phonons and influence the superconductivity in the second

  2. Tuning the Superconducting Properties of Magnesium Diboride

    SciTech Connect

    Theoderich Wilke, Rudeger Heinrich

    2005-01-01

    This work is presented in the following order: A review of the relevant physics and discussion of theoretical predictions for a two gap superconducting compound is given in chapter 2. Chapter 3 provides a review of the basic properties of MgB2. Details of sample synthesis and characterization are given in chapter 4. Chapter 5 presents normal state and superconducting properties of Mg(B1-xCx)2 wires. Attempts to increase critical current densities in filaments via titanium additions are discussed in chapter 6. In chapters 7 and 8 alternative methods for synthesizing doped MgB2 powders are explored. In chapter 7 we synthesize Mg(B1-xCx)2 up to x=0.069 using a mixture of Mg, B, and the binary compound B4C. Chapter 8 explores an alternative method, plasma spray synthesis, to produce nanometer sized doped boron powders for powder-in-tube applications. The effects of neutron irradiation on pure MgB2 wires is discussed in chapter 9. This is followed by a study of the effects of neutron irradiation on Mg(B.962C.038)2 wires, presented in chapter 10. I will summarize the results of all of these studies in chapter 11 and discuss future directions for research in understanding the physics behind this novel material as well as its development for practical applications. In this thesis I have presented the results of investigations into the changes in the superconducting properties of MgB2 as a function of carbon doping and neutron irradiation. The goal has been to understand the physics underlying this unique two-gap superconductor as different types of perturbations are made to the system. Such knowledge not only contributes to our understanding of two-gap superconductivity, but could potentially lead to the development of superconducting MgB2 wires for the use in power applications near 20 K.

  3. Process for producing clad superconductive materials

    DOEpatents

    Cass, Richard B.; Ott, Kevin C.; Peterson, Dean E.

    1992-01-01

    A process for fabricating superconducting composite wire by the steps of placing a superconductive precursor admixture capable of undergoing a self propagating combustion in stoichiometric amounts sufficient to form a superconductive product within a metal tube, sealing one end of said tube, igniting said superconductive precursor admixture whereby said superconductive precursor admixture endburns along the length of the admixture, and cross-section reducing said tube at a rate substantially equal to the rate of burning of said superconductive precursor admixture and at a point substantially planar with the burnfront of the superconductive precursor mixture, whereby a clad superconductive product is formed in situ, the product characterized as superconductive without a subsequent sintering stage, is disclosed.

  4. Large magnetoresistance of insulating silicon films with superconducting nanoprecipitates

    NASA Astrophysics Data System (ADS)

    Heera, V.; Fiedler, J.; Skorupa, W.

    2016-10-01

    We report on large negative and positive magnetoresistance in inhomogeneous, insulating Si:Ga films below a critical temperature of about 7 K. The magnetoresistance effect exceeds 300 % at temperatures below 3 K and fields of 8 T. The comparison of the transport properties of superconducting samples with that of insulating ones reveals that the large magnetoresistance is associated with the appearance of local superconductivity. A simple phenomenological model based on localized Cooper pairs and hopping quasiparticles is able to describe the temperature and magnetic field dependence of the sheet resistance of such films.

  5. Quantum phase slips in superconducting Nb nanowire networks deposited on self-assembled Si templates

    NASA Astrophysics Data System (ADS)

    Cirillo, C.; Trezza, M.; Chiarella, F.; Vecchione, A.; Bondarenko, V. P.; Prischepa, S. L.; Attanasio, C.

    2012-10-01

    Robust porous silicon substrates were employed for generating interconnected networks of superconducting ultrathin Nb nanowires. Scanning electron microscopy analysis was performed to investigate the morphology of the samples, which constitute of polycrystalline single wires with grain size of about 10 nm. The samples exhibit nonzero resistance over a broad temperature range below the critical temperature, fingerprint of phase slippage processes. The transport data are satisfactory reproduced by models describing both thermal and quantum fluctuations of the superconducting order parameter in thin homogeneous superconducting wires.

  6. Improvement and protection of niobium surface superconductivity by atomic layer deposition and heat treatment

    SciTech Connect

    Proslier, T.; Zasadzinski, J.; Moore, J.; Pellin, M.; Elam, J.; Cooley, L.; Antoine, C.; /Saclay

    2008-11-01

    A method to treat the surface of Nb is described, which potentially can improve the performance of superconducting rf cavities. We present tunneling and x-ray photoemission spectroscopy measurements at the surface of cavity-grade niobium samples coated with a 3 nm alumina overlayer deposited by atomic layer deposition. The coated samples baked in ultrahigh vacuum at low temperature degraded superconducting surface. However, at temperatures above 450 C, the tunneling conductance curves show significant improvements in the superconducting density of states compared with untreated surfaces.

  7. Figure correction of multilayer coated optics

    DOEpatents

    Chapman; Henry N. , Taylor; John S.

    2010-02-16

    A process is provided for producing near-perfect optical surfaces, for EUV and soft-x-ray optics. The method involves polishing or otherwise figuring the multilayer coating that has been deposited on an optical substrate, in order to correct for errors in the figure of the substrate and coating. A method such as ion-beam milling is used to remove material from the multilayer coating by an amount that varies in a specified way across the substrate. The phase of the EUV light that is reflected from the multilayer will be affected by the amount of multilayer material removed, but this effect will be reduced by a factor of 1-n as compared with height variations of the substrate, where n is the average refractive index of the multilayer.

  8. Multilayer Nanoporous Graphene Membranes for Water Desalination.

    PubMed

    Cohen-Tanugi, David; Lin, Li-Chiang; Grossman, Jeffrey C

    2016-02-10

    While single-layer nanoporous graphene (NPG) has shown promise as a reverse osmosis (RO) desalination membrane, multilayer graphene membranes can be synthesized more economically than the single-layer material. In this work, we build upon the knowledge gained to date toward single-layer graphene to explore how multilayer NPG might serve as a RO membrane in water desalination using classical molecular dynamic simulations. We show that, while multilayer NPG exhibits similarly promising desalination properties to single-layer membranes, their separation performance can be designed by manipulating various configurational variables in the multilayer case. This work establishes an atomic-level understanding of the effects of additional NPG layers, layer separation, and pore alignment on desalination performance, providing useful guidelines for the design of multilayer NPG membranes.

  9. Structural inhomogeneities in FeTe0.6Se0.4: Relation to superconductivity

    NASA Astrophysics Data System (ADS)

    Prokeš, K.; Schulze, M.; Hartwig, S.; Schäfer, N.; Landsgesell, S.; Blum, C. G. F.; Abou-Ras, D.; Hacisalihoglu, M. Y.; Ressouche, E.; Ouladdiaf, B.; Büchner, B.; Wurmehl, S.

    2015-12-01

    Chemical and structural phase compositions of two single-crystalline samples prepared with different cooling rates from stoichiometric FeTe0.6Se0.4 melts were studied. Both types of samples were investigated in a very comprehensive way using magnetic and electrical transport measurements combined with X-ray, neutron and electron backscatter diffraction. We show that slowly cooled samples are homogeneous on a microscopic scale with only a small excess of iron. Those slowly cooled samples do not exhibit bulk superconductivity down to 1.8 K. In contrast, fast-cooled samples are superconducting below about 14 K but are composed of several chemical phases: they consist of a matrix preserving the crystal structure of slow-cooled samples, and of core-shell structured dendritic inclusions (about 20-30 vol%). These have different crystal structures and chemical compositions and order magnetically at temperatures far above the superconducting transition temperature of the inhomogeneous samples. These structural and chemical inhomogeneities seem to play a vital role in the superconducting properties of this and similar iron-based systems as they lead to internal stress and act in a similar way as the application of the external pressure that reportedly increase the superconducting transition temperature in many iron pnictides and chalcogenides. We argue that a phase pure, homogeneous and stress-free FeTe0.6Se0.4 is non-superconducting.

  10. Impact on multilayered composite plates

    NASA Technical Reports Server (NTRS)

    Kim, B. S.; Moon, F. C.

    1977-01-01

    Stress wave propagation in a multilayer composite plate due to impact was examined by means of the anisotropic elasticity theory. The plate was modelled as a number of identical anisotropic layers and the approximate plate theory of Mindlin was then applied to each layer to obtain a set of difference-differential equations of motion. Dispersion relations for harmonic waves and correction factors were found. The governing equations were reduced to difference equations via integral transforms. With given impact boundary conditions these equations were solved for an arbitrary number of layers in the plate and the transient propagation of waves was calculated by means of a Fast Fourier Transform algorithm. The multilayered plate problem was extended to examine the effect of damping layers present between two elastic layers. A reduction of the interlaminar normal stress was significant when the thickness of damping layer was increased but the effect was mostly due to the softness of the damping layer. Finally, the problem of a composite plate with a crack on the interlaminar boundary was formulated.

  11. A beamline for high-pressure studies at the Advanced Light Source with a superconducting bending magnet as the source.

    PubMed

    Kunz, Martin; MacDowell, Alastair A; Caldwell, Wendel A; Cambie, Daniella; Celestre, Richard S; Domning, Edward E; Duarte, Robert M; Gleason, Arianna E; Glossinger, James M; Kelez, Nicholas; Plate, David W; Yu, Tony; Zaug, Joeseph M; Padmore, Howard A; Jeanloz, Raymond; Alivisatos, A Paul; Clark, Simon M

    2005-09-01

    A new facility for high-pressure diffraction and spectroscopy using diamond anvil high-pressure cells has been built at the Advanced Light Source on beamline 12.2.2. This beamline benefits from the hard X-radiation generated by a 6 T superconducting bending magnet (superbend). Useful X-ray flux is available between 5 keV and 35 keV. The radiation is transferred from the superbend to the experimental enclosure by the brightness-preserving optics of the beamline. These optics are comprised of a plane parabola collimating mirror, followed by a Kohzu monochromator vessel with Si(111) crystals (E/DeltaE approximately equal 7000) and W/B4C multilayers (E/DeltaE approximately equal 100), and then a toroidal focusing mirror with variable focusing distance. The experimental enclosure contains an automated beam-positioning system, a set of slits, ion chambers, the sample positioning goniometry and area detector (CCD or image-plate detector). Future developments aim at the installation of a second endstation dedicated to in situ laser heating and a dedicated high-pressure single-crystal station, applying both monochromatic and polychromatic techniques.

  12. A Beamline for High-Pressure Studies at the Advanced Light Sourcewith a Superconducting Bending Magnet as the Source

    SciTech Connect

    Kunz, Martin; MacDowell, Alastair A.; Caldwell, Wendel A.; Cambie, Daniella; Celestre, Richard S.; Domning, Edward E.; Duarte,Robert M.; Gleason, Arianna E.; Glossinger, James M.; Kelez, Nicholas; Plate, David W.; Yu, Tony; Zaug, Joeseph M.; Padmore, Howard A.; Jeanloz,Raymond; Alivisatos, A. Paul; Clark, Simon M.

    2005-06-30

    A new facility for high-pressure diffraction andspectroscopy using diamond anvil high-pressure cells has been built atthe Advanced Light Source on Beamline 12.2.2. This beamline benefits fromthe hard X-radiation generated by a 6 Tesla superconducting bendingmagnet (superbend). Useful x-ray flux is available between 5 keV and 35keV. The radiation is transferred from the superbend to the experimentalenclosure by the brightness preserving optics of the beamline. Theseoptics are comprised of: a plane parabola collimating mirror (M1),followed by a Kohzu monochromator vessel with a Si(111) crystals (E/DE ~;7000) and a W/B4C multilayers (E/DE ~; 100), and then a toroidal focusingmirror (M2) with variable focusing distance. The experimental enclosurecontains an automated beam positioning system, a set of slits, ionchambers, the sample positioning goniometry and area detectors (CCD orimage-plate detector). Future developments aim at the installation of asecond end station dedicated for in situ laser-heating on one hand and adedicated high-pressure single-crystal station, applying bothmonochromatic as well as polychromatic techniques.

  13. A BEAMLINE FOR HIGH PRESSURE STUDIES AT THE ADVANCED LIGHT SOURCE WITH A SUPERCONDUCTING BENDING MAGNET AS THE SOURCE

    SciTech Connect

    Kunz, M; MacDowell, A A; Caldwell, W A; Cambie, D; Celestre, R S; Domning, E E; Duarte, R M; Gleason, A; Glossinger, J; Kelez, N; Plate, D W; Yu, T; Zaug, J M; Padmore, H A; Jeanloz, R; Alivisatos, A P; Clark, S M

    2005-04-19

    A new facility for high-pressure diffraction and spectroscopy using diamond anvil high-pressure cells has been built at the Advanced Light Source on Beamline 12.2.2. This beamline benefits from the hard X-radiation generated by a 6 Tesla superconducting bending magnet (superbend). Useful x-ray flux is available between 5 keV and 35 keV. The radiation is transferred from the superbend to the experimental enclosure by the brightness preserving optics of the beamline. These optics are comprised of: a plane parabola collimating mirror (M1), followed by a Kohzu monochromator vessel with a Si(111) crystals (E/{Delta}E {approx} 7000) and a W/B{sub 4}C multilayer (E/{Delta}E {approx} 100), and then a toroidal focusing mirror (M2) with variable focusing distance. The experimental enclosure contains an automated beam positioning system, a set of slits, ion chambers, the sample positioning goniometry and area detectors (CCD or image-plate detector). Future developments aim at the installation of a second end station dedicated for in situ laser-heating on one hand and a dedicated high-pressure single-crystal station, applying both monochromatic as well as polychromatic techniques.

  14. A Beamline for High-Pressure Studies at the Advanced Light Sourcewith a Superconducting Bending Magnet as the Source

    SciTech Connect

    Kunz, Martin; MacDowell, Alastair A.; Caldwell, Wendel A.; Cambie, Daniella; Celestre, Richard S.; Domning, Edward E.; Duarte,Robert M.; Gleason, Arianna E.; Glossinger, James M.; Kelez, Nicholas; Plate, David W.; Yu, Tony; Zaug, Joeseph M.; Padmore, Howard A.; Jeanloz,Raymond; Alivisatos, A. Paul; Clark, Simon M.

    2005-06-30

    A new facility for high-pressure diffraction and spectroscopy using diamond anvil high-pressure cells has been built at the Advanced Light Source on Beamline 12.2.2. This beamline benefits from the hard X-radiation generated by a 6 Tesla superconducting bending magnet (superbend). Useful x-ray flux is available between 5 keV and 35 keV. The radiation is transferred from the superbend to the experimental enclosure by the brightness preserving optics of the beamline. These optics are comprised of: a plane parabola collimating mirror (M1), followed by a Kohzu monochromator vessel with a Si(111) crystals (E/DE {approx}7000) and a W/B4C multilayers (E/DE {approx} 100), and then a toroidal focusing mirror (M2) with variable focusing distance. The experimental enclosure contains an automated beam positioning system, a set of slits, ion chambers, the sample positioning goniometry and area detectors (CCD or image-plate detector). Future developments aim at the installation of a second end station dedicated for in situ laser-heating on one hand and a dedicated high-pressure single-crystal station, applying both monochromatic as well as polychromatic techniques.

  15. Dimensionality crossover in ferromagnetic/superconducting films: Role of magnetic history

    NASA Astrophysics Data System (ADS)

    Ruiz-Valdepeñas, Luis; Valdes-Bango, Fernando; Alvarez-Prado, Luis; Martin, Jose; Navarro, Elena; Velez, Maria; Alameda, Jose; Vicent, Jose

    2014-03-01

    Amorphous NdCo5 films are ferromagnetic samples with a weak perpendicular magnetic anisotropy which can show small magnetic domain sizes (less than 100 nm) with labyrinthine structures. Sputtering technique is used to fabricate Nb/Al(5nm)/ NdCo5 superconducting films on Si substrates. The temperature dependence of the upper critical field shows features which could be related to an ``imprinting'' of the domain structure of NdCo5 layers in the superconducting Nb film. This peculiar proximity effect governs the superconductivity dimensionality crossover from 1D to a regime between 1D and 2D typical of superconducting wire network. This superconducting crossover can be connected to the NdCo5 magnetic history. We thank support from Spanish MINECO and CAM.

  16. Fractal superconductivity near localization threshold

    SciTech Connect

    Feigel'man, M.V.; Ioffe, L.B.; Kravtsov, V.E.; Cuevas, E.

    2010-07-15

    We develop a semi-quantitative theory of electron pairing and resulting superconductivity in bulk 'poor conductors' in which Fermi energy E{sub F} is located in the region of localized states not so far from the Anderson mobility edge E{sub c}. We assume attractive interaction between electrons near the Fermi surface. We review the existing theories and experimental data and argue that a large class of disordered films is described by this model. Our theoretical analysis is based on analytical treatment of pairing correlations, described in the basis of the exact single-particle eigenstates of the 3D Anderson model, which we combine with numerical data on eigenfunction correlations. Fractal nature of critical wavefunction's correlations is shown to be crucial for the physics of these systems. We identify three distinct phases: 'critical' superconductive state formed at E{sub F} = E{sub c}, superconducting state with a strong pseudo-gap, realized due to pairing of weakly localized electrons and insulating state realized at E{sub F} still deeper inside a localized band. The 'critical' superconducting phase is characterized by the enhancement of the transition temperature with respect to BCS result, by the inhomogeneous spatial distribution of superconductive order parameter and local density of states. The major new feature of the pseudo-gapped state is the presence of two independent energy scales: superconducting gap {Delta}, that is due to many-body correlations and a new 'pseudo-gap' energy scale {Delta}{sub P} which characterizes typical binding energy of localized electron pairs and leads to the insulating behavior of the resistivity as a function of temperature above superconductive T{sub c}. Two gap nature of the pseudo-gapped superconductor is shown to lead to specific features seen in scanning tunneling spectroscopy and point-contact Andreev spectroscopy. We predict that pseudo-gapped superconducting state demonstrates anomalous behavior of the optical

  17. A Closed Neon Liquefier System for Testing Superconducting Devices

    NASA Astrophysics Data System (ADS)

    Bianchetti, M.; Al-Mosawi, M. K.; Yang, Y.; Beduz, C.; Giunchi, G.

    2006-04-01

    A Neon liquefier system has been developed by Southampton University (UK) and EDISON (Italy) with the aim to provide a facility for testing HTS superconducting devices using Magnesium Diboride materials, in the range 25-30K. The system consists of a liquid Neon cryostat coupled to a two stages cryocooler and a recovery system. The first stage of the cryocooler is connected to the thermal shield of the cryostat and a copper station positioned at mid point along the access neck to the liquid Neon bath to reduce heat leak and to provide pre-cooling of samples. The second stage, capable of 20W cooling power at 22K, is used to provide the cooling power for liquefaction and to refrigerate the liquid Neon bath and the superconducting device/sample during the steady state operation. The recovery system has been designed to automatically compress excess boil-off generated by a quench or a transient heating into a storage gas container. Transport measurement up to 900A can be carried out in the Ne cryostat using purposely build hybrid current leads. These leads have a copper upper section cooled by liquid Nitrogen and a superconducting lower section of Ag/AuBi2223 tapes. In this paper we report on the performance of the system and the initial measurement of superconducting samples.

  18. Scanning Tunnelling Spectroscopy of Vortices with Normal and Superconducting tips

    NASA Astrophysics Data System (ADS)

    Rodrigo, J. G.; Suderow, H.; Vieira, S.

    Scanning tunnelling microscopy and spectroscopy (STM/S) has proved to be a powerful tool to study superconductivity down to atomic level. Vortex lattice studies require characterizing areas of enough size to contain a large number of vortices. On the other hand, it is necessary to combine this capability with high spectroscopic and microscopic resolution. This is a fundamental aspect to measure and detect the subtle changes appearing inside and around a single vortex. We report in this chapter our approach to the use of STM/S, using normal and superconducting tips, to observe the lattice of vortices in several compounds, and the information acquired inside these fascinating entities. The combination of superconducting tips and scanning tunneling spectroscopy, (ST)2S, presents advantages for the study of superconducting samples. It allows to distinguish relevant features of the sample density of states, which manifest itself as small changes in the Josephson coupling between sample and tip condensates, and it has also shown to be very efficient in the study of the ferromagnetic-superconductor transition in the re-entrant superconductor ErRh4B4.

  19. X-ray studies of microstructures in semiconductors and superconducting materials

    SciTech Connect

    Kao, Y.H.

    1992-04-01

    Objective is to use synchrotron x rays to probe short-range-order (SRO) structures in these materials. These SRO structures, with a scale of a few angstroms, include these around interfaces in multilayers, strain and local environs around impurity or constituent atoms, as well as lattice mismatch, intermixing of atoms across interfaces, annealing, etc. A new soft x-ray detector has been built and was used to measure x-ray fluorescence from O and F in bulk materials. The research on microstructure in both semiconductors and high-T{sub c} superconductors is being continued with emphasis on multilayer materials. X-ray absorption fine structure spectroscopy is being used in many of the studies, as is grazing incidence x-ray fluorescence and scattering. Total electron yield is used with fluorescence to probe surfaces and interfaces. Effects of doping on superconducting properties, especially these related to microstructures around impurities or constituent atoms, were studied. Resulting papers are listed.

  20. Effect of separating layer thickness on W/Si multilayer replication.

    PubMed

    Wang, Fangfang; Mu, Baozhong; Jin, Huijun; Yang, Xiajun; Zhu, Jingtao; Wang, Zhanshan

    2011-08-15

    The direct replication of W/Si multilayers and the effect of separating layer thickness on the performance of the multilayer before and after replication are investigated systematically. Platinum separating layers with different layer thicknesses were first deposited onto different supersmooth mandrels and then W/Si multilayers with the similar structure were deposited onto these Pt-coated mandrels by using a high vacuum DC magnetron sputtering system. After the deposition, these multilayers were replicated onto the commercially available float glass substrates by epoxy replication technique. These multilayers before and after replication are characterized by grazing-incident X-ray reflectance measurement and atomic force microscope. The measured results show that before and after replication, the reflectivity curves are much similar to those calculated and the surface roughness of each sample is close to that of the mandrel, when the separating layer thickness is larger than 1.5 nm. These results reveal that the W/Si multilayer with the separating layer thickness larger than 1.5 nm can be successfully replicated onto a substrate without modification of the structure, significant increase of surface roughness or apparent change of reflectivity.

  1. Structural transformations in Sc/Si multilayers irradiated by EUV lasers

    NASA Astrophysics Data System (ADS)

    Voronov, Dmitriy L.; Zubarev, Evgeniy N.; Pershyn, Yuriy P.; Sevryukova, Victoriya A.; Kondratenko, Valeriy V.; Vinogradov, Alexander V.; Artioukov, Igor A.; Uspenskiy, Yuriy A.; Grisham, Michael; Vaschenko, Georgiy; Menoni, Carmen S.; Rocca, Jorge J.

    2007-09-01

    Multilayer mirrors for the extreme ultraviolet (EUV) are key elements for numerous applications of coherent EUV sources such as new tabletop lasers and free-electron lasers. However the field of applications is limited by the radiation and thermal stability of the multilayers. Taking into account the growing power of EUV sources the stability of the optics becomes crucial. To overcome this problem it is necessary to study the degradation of multilayers and try to increase their temporal and thermal stability. In this paper we report the results of detailed study of structural changes in Sc/Si multilayers when exposed to intense EUV laser pulses. Various types of surface damage such as melting, boiling, shock wave creation and ablation were observed as irradiation fluencies increase. Cross-sectional TEM study revealed that the layer structure was completely destroyed in the upper part of multilayer, but still survived below. The layers adjacent to the substrate remained intact even through the multilayer surface melted down, though the structure of the layers beneath the molten zone was noticeably changed. The layer structure in this thermally affected zone is similar to that of isothermally annealed samples. All stages of scandium silicide formation such as interdiffusion, solid-state amorphization, silicide crystallization etc., are present in the thermally affected zone. It indicates a thermal nature of the damage mechanism. The tungsten diffusion barriers were applied to the scandium/silicon interfaces. It was shown that the barriers inhibited interdiffusion and increased the thermal stability of Sc/Si mirrors.

  2. Pressure-induced electronic phase separation of magnetism and superconductivity in CrAs

    PubMed Central

    Khasanov, Rustem; Guguchia, Zurab; Eremin, Ilya; Luetkens, Hubertus; Amato, Alex; Biswas, Pabitra K.; Rüegg, Christian; Susner, Michael A.; Sefat, Athena S.; Zhigadlo, Nikolai D.; Morenzoni, Elvezio

    2015-01-01

    The recent discovery of pressure (p) induced superconductivity in the binary helimagnet CrAs has raised questions on how superconductivity emerges from the magnetic state and on the mechanism of the superconducting pairing. In the present work the suppression of magnetism and the occurrence of superconductivity in CrAs were studied by means of muon spin rotation. The magnetism remains bulk up to p  3.5 kbar while its volume fraction gradually decreases with increasing pressure until it vanishes at p  7 kbar. At 3.5 kbar superconductivity abruptly appears with its maximum Tc  1.2 K which decreases upon increasing the pressure. In the intermediate pressure region (3.5  p  7 kbar) the superconducting and the magnetic volume fractions are spatially phase separated and compete for phase volume. Our results indicate that the less conductive magnetic phase provides additional carriers (doping) to the superconducting parts of the CrAs sample thus leading to an increase of the transition temperature (Tc) and of the superfluid density (ρs). A scaling of ρs with as well as the phase separation between magnetism and superconductivity point to a conventional mechanism of the Cooper-pairing in CrAs. PMID:26346548

  3. Pressure-induced electronic phase separation of magnetism and superconductivity in CrAs.

    PubMed

    Khasanov, Rustem; Guguchia, Zurab; Eremin, Ilya; Luetkens, Hubertus; Amato, Alex; Biswas, Pabitra K; Rüegg, Christian; Susner, Michael A; Sefat, Athena S; Zhigadlo, Nikolai D; Morenzoni, Elvezio

    2015-09-08

    The recent discovery of pressure (p) induced superconductivity in the binary helimagnet CrAs has raised questions on how superconductivity emerges from the magnetic state and on the mechanism of the superconducting pairing. In the present work the suppression of magnetism and the occurrence of superconductivity in CrAs were studied by means of muon spin rotation. The magnetism remains bulk up to p ≃ 3.5 kbar while its volume fraction gradually decreases with increasing pressure until it vanishes at p ≃ 7 kbar. At 3.5 kbar superconductivity abruptly appears with its maximum Tc ≃ 1.2 K which decreases upon increasing the pressure. In the intermediate pressure region (3.5 < or ~  p < or ~ 7 kbar) the superconducting and the magnetic volume fractions are spatially phase separated and compete for phase volume. Our results indicate that the less conductive magnetic phase provides additional carriers (doping) to the superconducting parts of the CrAs sample thus leading to an increase of the transition temperature (Tc) and of the superfluid density (ρs). A scaling of ρs with Tc(3.2) as well as the phase separation between magnetism and superconductivity point to a conventional mechanism of the Cooper-pairing in CrAs.

  4. Pressure-induced electronic phase separation of magnetism and superconductivity in CrAs

    SciTech Connect

    Khasanov, Rustem; Guguchia, Zurab; Eremin, Ilya; Luetkens, Hubertus; Amato, Alex; Biswas, Pabitra K.; Ruegg, Christian; Susner, Michael A.; Sefat, Athena S.; Zhigadlo, Nikolai D.; Morenzoni, Elvezio

    2015-09-08

    We report that the recent discovery of pressure (p) induced superconductivity in the binary helimagnet CrAs has raised questions on how superconductivity emerges from the magnetic state and on the mechanism of the superconducting pairing. In the present work the suppression of magnetism and the occurrence of superconductivity in CrAs were studied by means of muon spin rotation. The magnetism remains bulk up to p ≃ 3.5 kbar while its volume fraction gradually decreases with increasing pressure until it vanishes at p ≃ 7 kbar. At 3.5 kbar superconductivity abruptly appears with its maximum Tc ≃ 1.2 K which decreases upon increasing the pressure. In the intermediate pressure region (3.5≲ p ≲ 7 kbar) the superconducting and the magnetic volume fractions are spatially phase separated and compete for phase volume. Our results indicate that the less conductive magnetic phase provides additional carriers (doping) to the superconducting parts of the CrAs sample thus leading to an increase of the transition temperature (Tc) and of the superfluid density (ρs). A scaling of ρs with Tc3.2 as well as the phase separation between magnetism and superconductivity point to a conventional mechanism of the Cooper-pairing in CrAs.

  5. Pressure-induced electronic phase separation of magnetism and superconductivity in CrAs

    DOE PAGES

    Khasanov, Rustem; Guguchia, Zurab; Eremin, Ilya; ...

    2015-09-08

    We report that the recent discovery of pressure (p) induced superconductivity in the binary helimagnet CrAs has raised questions on how superconductivity emerges from the magnetic state and on the mechanism of the superconducting pairing. In the present work the suppression of magnetism and the occurrence of superconductivity in CrAs were studied by means of muon spin rotation. The magnetism remains bulk up to p ≃ 3.5 kbar while its volume fraction gradually decreases with increasing pressure until it vanishes at p ≃ 7 kbar. At 3.5 kbar superconductivity abruptly appears with its maximum Tc ≃ 1.2 K which decreasesmore » upon increasing the pressure. In the intermediate pressure region (3.5≲ p ≲ 7 kbar) the superconducting and the magnetic volume fractions are spatially phase separated and compete for phase volume. Our results indicate that the less conductive magnetic phase provides additional carriers (doping) to the superconducting parts of the CrAs sample thus leading to an increase of the transition temperature (Tc) and of the superfluid density (ρs). A scaling of ρs with Tc3.2 as well as the phase separation between magnetism and superconductivity point to a conventional mechanism of the Cooper-pairing in CrAs.« less

  6. The road to superconducting spintronics

    NASA Astrophysics Data System (ADS)

    Eschrig, Matthias

    Energy efficient computing has become a major challenge, with the increasing importance of large data centres across the world, which already today have a power consumption comparable to that of Spain, with steeply increasing trend. Superconducting computing is progressively becoming an alternative for large-scale applications, with the costs for cooling being largely outweighed by the gain in energy efficiency. The combination of superconductivity and spintronics - ``superspintronics'' - has the potential and flexibility to develop into such a green technology. This young field is based on the observation that new phenomena emerge at interfaces between superconducting and other, competing, phases. The past 15 years have seen a series of pivotal predictions and experimental discoveries relating to the interplay between superconductivity and ferromagnetism. The building blocks of superspintronics are equal-spin Cooper pairs, which are generated at the interface between superconducting and a ferromagnetic materials in the presence of non-collinear magnetism. Such novel, spin-polarised Cooper pairs carry spin-supercurrents in ferromagnets and thus contribute to spin-transport and spin-control. Geometric Berry phases appear during the singlet-triplet conversion process in structures with non-coplanar magnetisation, enhancing functionality of devices, and non-locality introduced by superconducting order leads to long-range effects. With the successful generation and control of equal-spin Cooper pairs the hitherto notorious incompatibility of superconductivity and ferromagnetism has been not only overcome, but turned synergistic. I will discuss these developments and their extraordinary potential. I also will present open questions posed by recent experiments and point out implications for theory. This work is supported by the Engineering and Physical Science Research Council (EPSRC Grant No. EP/J010618/1).

  7. Dynamics of driven superconducting vortices

    NASA Astrophysics Data System (ADS)

    Reichhardt, Cynthia Olson

    1998-09-01

    Vortices in superconductors exhibit rich dynamical behaviors that are relevant to the physical properties of the material. In this thesis, we use simulations to study the dynamics of flux-gradient-driven vortices in different types of samples. We make connections between the microscopic behavior of the vortices and macroscopic experimentally observable measurements. First, we systematically quantify the effect of the pinning landscape on the macroscopic properties of vortex avalanches and vortex plastic flow. We relate the velocity field, cumulative patterns of vortex flow channels, and voltage noise measurements with statistical quantities, such as distributions of avalanche sizes. Samples with a high density of strong pinning sites produce very broad avalanche distributions. Easy-flow vortex channels appear in samples with a low pinning density, and typical avalanche sizes emerge in an otherwise broad distribution of sizes. We observe a crossover from interstitial motion in narrow channels to pin-to-pin motion in broad channels as the pin density is increased. Second, we also analyze the microscopic dynamics of vortex motion through channels that form river-like fractal networks in a variety of superconducting samples, and relate it to macroscopic measurable quantities such as the power spectrum. As a function of pinning strength, we calculate the fractal dimension, tortuosity, and the corresponding voltage noise spectrum. Above a certain pinning strength, a remarkable universal drop in both tortuosity and noise power occurs when the vortex motion changes from braiding channels to unbraided channels. Third, we also present a new dynamic phase diagram for driven vortices with varying lattice softness that indicates that, at high driving currents, at least two distinct dynamic phases of flux flow appear depending on the vortex-vortex interaction strength. When the flux lattice is soft, the vortices flow in independently moving channels with smectic structure. For

  8. Improved superconducting magnet wire

    DOEpatents

    Schuller, I.K.; Ketterson, J.B.

    1983-08-16

    This invention is directed to a superconducting tape or wire composed of alternating layers of copper and a niobium-containing superconductor such as niobium of NbTi, Nb/sub 3/Sn or Nb/sub 3/Ge. In general, each layer of the niobium-containing superconductor has a thickness in the range of about 0.05 to 1.5 times its coherence length (which for Nb/sub 3/Si is 41 A) with each copper layer having a thickness in the range of about 170 to 600 A. With the use of very thin layers of the niobium composition having a thickness within the desired range, the critical field (H/sub c/) may be increased by factors of 2 to 4. Also, the thin layers of the superconductor permit the resulting tape or wire to exhibit suitable ductility for winding on a magnet core. These compositions are also characterized by relatively high values of critical temperature and therefore will exhibit a combination of useful properties as superconductors.

  9. Superconducting energy storage magnet

    NASA Technical Reports Server (NTRS)

    Boom, Roger W. (Inventor); Eyssa, Yehia M. (Inventor); Abdelsalam, Mostafa K. (Inventor); Huang, Xianrui (Inventor)

    1993-01-01

    A superconducting magnet is formed having composite conductors arrayed in coils having turns which lie on a surface defining substantially a frustum of a cone. The conical angle with respect to the central axis is preferably selected such that the magnetic pressure on the coil at the widest portion of the cone is substantially zero. The magnet structure is adapted for use as an energy storage magnet mounted in an earthen trench or tunnel where the strength the surrounding soil is lower at the top of the trench or tunnel than at the bottom. The composite conductor may be formed having a ripple shape to minimize stresses during charge up and discharge and has a shape for each ripple selected such that the conductor undergoes a minimum amount of bending during the charge and discharge cycle. By minimizing bending, the working of the normal conductor in the composite conductor is minimized, thereby reducing the increase in resistance of the normal conductor that occurs over time as the conductor undergoes bending during numerous charge and discharge cycles.

  10. Superconducting wire manufactured

    NASA Astrophysics Data System (ADS)

    Fu, Yuexian; Sun, Yue; Xu, Shiming; Peng, Ying

    1985-10-01

    The MF Nb/Cu Extrusion Tube Method was used to manufacture 3 kg of stable practical MF Nb2Sn composite superconducting wire containing pure Cu(RRR approx. 200)/Ta. The draw state composite wire diameter was 0.56 mm, it contained 11,448 x 2.6 micron Nb core, and the twist distance was 1.5 cm. The composite wire cross-section was pure Cu/Ta/11,448 Nb core/Cu/ 91Sn-Cu; containing 22.8 v. % pure Cu, 13.3 v. % Ta; within the Ta layer to prevent Sn diffusion. The wire was sheathed in nonalkaline glass fiber as an insulating layer. A section of wire weighing 160 g was cut off and coiled it into a small solenoid. After reaction diffusion processing at 675 C/30 and curing by vacuum dipping in paraffin, it was measured in a Nb-Ti backfield of 7.2 T intensity, a current of 129 A was passed through the Nb3Sn solenoid and produced a strength of 2.5 T, the overall magnetic field intensity of the composite magnet reached 9.7 T. At this time, the wire full current density J sub c.w. = 5.2 x 10 to the 4th power A/sq cm; the effective current density J sub c (Nb + Sn - Cu) = 8.2 x 10 to the 4th power A/sq cm.

  11. Radiation Heat Measurement on Thermally-Isolated Double-Pipe for DC Superconducting Power Transmission

    NASA Astrophysics Data System (ADS)

    Hamabe, M.; Nasu, Y.; Ninomiya, A.; Ishiguro, Y.; Kusaka, S.; Yamaguchi, S.

    2008-03-01

    Multilayer insulator (MLI) is a strong tool for use as a radiation heat shield, though the use of MLI has disadvantages in construction and evacuation for a long superconducting power cable. We have proposed the "MLI-free" radiation heat shielding for DC superconducting power cable and have measured the radiation heat transfer for thermally-isolated double-pipes with different surfaces. Here, Zn coating, MLI, and Al-foil sheet were tested. Consequently, from the radiation heat of 9.7 W/m for bare stainless-steel pipe, Zn-coated stainless-steel surface reduced to 2.6 W/m, whereas the use of MLI reduced to 0.2 W/m. It is expected that the simultaneous use of Zn coating and MLI can reduce the number of total MLI sheets to reduce the evacuation time.

  12. Two-Dimensional Superconductivity in the Cuprates Revealed by Atomic-Layer-by- Layer Molecular Beam Epitaxy

    SciTech Connect

    A. T. Bollinger; Bozovic, I.

    2016-08-12

    Various electronic phases displayed by cuprates that exhibit high temperature superconductivity continue to attract much interest. We provide a short review of several experiments that we have performed aimed at investigating the superconducting state in these compounds. Measurements on single-phase films, bilayers, and superlattices all point to the conclusion that the high-temperature superconductivity in these materials is an essentially quasi-two dimensional phenomenon. With proper control over the film growth, high-temperature superconductivity can exist in a single copper oxide plane with the critical temperatures as high as that achieved in the bulk samples.

  13. Noise properties of high-Tc superconducting flux transformers fabricated using chemical-mechanical polishing

    NASA Astrophysics Data System (ADS)

    Chukharkin, M.; Kalabukhov, A.; Schneiderman, J. F.; Öisjöen, F.; Snigirev, O.; Lai, Z.; Winkler, D.

    2012-07-01

    Reproducible high-temperature superconducting multilayer flux transformers were fabricated using chemical mechanical polishing. The measured magnetic field noise of the flip-chip magnetometer based on one such flux transformer with a 9 × 9 mm2 pickup loop coupled to a bicrystal dc SQUID was 15 fT/Hz1/2 above 2 kHz. We present an investigation of excess 1/f noise observed at low frequencies and its relationship with the microstructure of the interlayer connections within the flux transformer. The developed high-Tc SQUID magnetometers may be advantageous in ultra-low field magnetic resonance imaging and, with improved low frequency noise, magnetoencephalography applications.

  14. Optimization of multilayer neural network parameters for speaker recognition

    NASA Astrophysics Data System (ADS)

    Tovarek, Jaromir; Partila, Pavol; Rozhon, Jan; Voznak, Miroslav; Skapa, Jan; Uhrin, Dominik; Chmelikova, Zdenka

    2016-05-01

    This article discusses the impact of multilayer neural network parameters for speaker identification. The main task of speaker identification is to find a specific person in the known set of speakers. It means that the voice of an unknown speaker (wanted person) belongs to a group of reference speakers from the voice database. One of the requests was to develop the text-independent system, which means to classify wanted person regardless of content and language. Multilayer neural network has been used for speaker identification in this research. Artificial neural network (ANN) needs to set parameters like activation function of neurons, steepness of activation functions, learning rate, the maximum number of iterations and a number of neurons in the hidden and output layers. ANN accuracy and validation time are directly influenced by the parameter settings. Different roles require different settings. Identification accuracy and ANN validation time were evaluated with the same input data but different parameter settings. The goal was to find parameters for the neural network with the highest precision and shortest validation time. Input data of neural networks are a Mel-frequency cepstral coefficients (MFCC). These parameters describe the properties of the vocal tract. Audio samples were recorded for all speakers in a laboratory environment. Training, testing and validation data set were split into 70, 15 and 15 %. The result of the research described in this article is different parameter setting for the multilayer neural network for four speakers.

  15. Formation of oriented membrane multilayers of Na/K-ATPase

    SciTech Connect

    Pachence, J.M.; Knott, R.; Edelman, I.S.; Schoenborn, B.P.; Wallace, B.A.

    1982-01-01

    The isolated membrane-bound enzyme retains its ouabain-sensitive ATP hydrolysis activity, and produces ATP-dependent Na/sup +/ and K/sup +/ fluxes when incorporated into phospholipid vesicles. The ultimate goal of this work is to determine its low resolution structure using both X-ray and neutron diffraction. A number of methods were used to impart lamellar stacking order to highly purified pig Na/K-ATPase membranes. Upon partial dehydration, x-ray diffraction from Na/K-ATPase membrane multilayers at 98% relative humidity yielded discrete reflections of 118 A periodicity, diffracting to 1/14.8 A/sup -1/, additionally, continuous diffraction to 1/10 A/sup -1/ was obtained. Subjecting the membrane multilayers to high magnetic fields improved the quality of the lamellar diffraction dramatically. Neutron diffraction studies of the partially dehydrated Na/K-ATPase membrane multilayers detected a mosaic spread of 2/sup 0/ when the samples were subjected to a magnetic field of 5 Tesla perpendicular to the membrane surface; the reflections were narrower than the camera line width; hence, the lattice disorder has also decreased significantly, although only four orders were measured.

  16. Ballistic electron emission spectroscopy of magnetic multilayers (abstract)

    NASA Astrophysics Data System (ADS)

    First, P. N.; Bonetti, J. A.; Guthrie, D. K.; Harrell, L. E.; Parkin, S. S. P.

    1997-04-01

    The giant magnetoresistance observed in magnetic multilayers arises from spin-dependent scattering and transmission of electrons at the Fermi energy. We will describe a method for the measurement of these quantities in a "CPP" geometry at electron energies both above and below the Fermi energy. Initial results will also be presented. The measurements employ ballistic electron emission spectroscopy (BEES) to detect the ballistic electron current transmitted through a multilayer as a function of magnetic field and electron energy. The experiments are similar in concept to the "spin-valve transistor,"1 except that the injector is the tip of a scanning tunneling microscope. This allows the injection energy to be varied over a wide range, and spectra can be correlated with the local surface morphology on a nanometer scale. Spectral broadening due to sample inhomogeneities is also eliminated. We anticipate that BEES measurements and complementary scanning tunneling spectroscopy will provide information that is easily compared with calculations of the multilayer band structure and the electron transmittance versus energy.

  17. A MEMS lamination technology based on sequential multilayer electrodeposition

    SciTech Connect

    Kim, M; Kim, J; Herrault, F; Schafer, R; Allen, MG

    2013-08-06

    A MEMS lamination technology based on sequential multilayer electrodeposition is presented. The process comprises three main steps: (1) automated sequential electrodeposition of permalloy (Ni80Fe20) structural and copper sacrificial layers to form multilayer structures of significant total thickness; (2) fabrication of polymeric anchor structures through the thickness of the multilayer structures and (3) selective removal of copper. The resulting structure is a set of air-insulated permalloy laminations, the separation of which is sustained by insulating polymeric anchor structures. Individual laminations have precisely controllable thicknesses ranging from 500 nm to 5 mu m, and each lamination layer is electrically isolated from adjacent layers by narrow air gaps of similar scale. In addition to air, interlamination insulators based on polymers are investigated. Interlamination air gaps with very high aspect ratio (>1:100) can be filled with polyvinylalcohol and polydimethylsiloxane. The laminated structures are characterized using scanning electron microscopy and atomic force microscopy to directly examine properties such as the roughness and the thickness uniformity of the layers. In addition, the quality of the electrical insulation between the laminations is evaluated by quantifying the eddy current within the sample as a function of frequency. Fabricated laminations are comprised of uniform, smooth (surface roughness < 100 nm) layers with effective electrical insulation for all layer thicknesses and insulator approaches studied. Such highly laminated structures have potential uses ranging from energy conversion to applications where composite materials with highly anisotropic mechanical or thermal properties are required.

  18. Magnetic-plasmonic multilayered nanorods

    NASA Astrophysics Data System (ADS)

    Thumthan, Orathai

    Multilayered nanorods which consist of alternating magnetic layers separated by Au layers combine two distinctive properties, magnetic properties and surface plasmonic resonance (SPR) properties into one nano-entity. Their magnetic properties are tunable by changing the layer thickness, varying from single domain to superparamagnetic state. Superparamagnetic is a key requirement for magnetic nanoparticles for bioapplications. Superparamagnetic nanoparticles exhibit high magnetic moments at low applied magnetic field while retain no magnetic moments when magnetic field is removed preventing them from aggregation due to magnetic attraction. Au layers in the nanorods provide anchorage sites for functional group attachment. Also, Au nanodisks exhibit SPR properties. The SPR peak can be tuned from 540 nm to 820 nm by controlling the thickness of magnetic segments while keeping Au thickness constant. In this research, there are three types of multilayered nanorod have been fabricated: Au/NiFe nanorods, Au/Fe nanorods, and Au/Co nanorods. These magnetic nanorods were fabricated by templated electrodeposition into the channels in Anodic Aluminum Oxide (AAO) membrane. The setup for AAO fabrication was developed as a part of this research. Our fabricated AAO membrane has channels with a diameter ranging from 40nm to 80 nm and a thickness of 10um to 12um. Magnetic properties of nanorods such as saturation field, saturation moment, coercivity and remanence are able to manipulate through their shape anisotropy. The magnetization will be easier in long axis rather than short axis of particle. In addition, Au nanodisks in the nanorod structure are not only serving as anchorage sites for functional groups but also provide SPR properties. Under irradiation of light Au nanodisks strongly absorb light at SPR frequency which ranging from 540 nm to 820 nm by controlling the thickness of magnetic segments while keeping Au thickness constant. The SPR tunability of nanorods in near

  19. The Superconducting Bird: A Didactical Toy.

    ERIC Educational Resources Information Center

    Guarner, E.; Sanchez, A. M.

    1992-01-01

    Describes the design of the superconducting bird, a device to demonstrate the phenomenon of superconductivity. Discusses the utilization of the device as an example of a motor and compares it to the toy called the drinking bird. (MDH)

  20. Optical multilayers with an amorphous fluoropolymer

    NASA Astrophysics Data System (ADS)

    Chow, Robert; Loomis, Gary E.; Lindsey, Edward F.

    1994-09-01

    Multilayered coatings were made by physical vapor deposition (PVD) of a perfluorinated amorphous polymer, Teflon AF2400, together with other optical materials. A high reflector at 1064 nm was made with ZnS and AF2400. An all-organic 1064-nm reflector was made from AF2400 and polyethylene. Oxide (HfO2, SiO2) compatibility was also tested. Each multilayer system adhered to itself. The multilayers were influenced by coating stress and unintentional temperature rises during PVD deposition.

  1. Multilayer composites and manufacture of same

    DOEpatents

    Holesinger, Terry G.; Jia, Quanxi

    2006-02-07

    The present invention is directed towards a process of depositing multilayer thin films, disk-shaped targets for deposition of multilayer thin films by a pulsed laser or pulsed electron beam deposition process, where the disk-shaped targets include at least two segments with differing compositions, and a multilayer thin film structure having alternating layers of a first composition and a second composition, a pair of the alternating layers defining a bi-layer wherein the thin film structure includes at least 20 bi-layers per micron of thin film such that an individual bi-layer has a thickness of less than about 100 nanometers.

  2. Superconducting six-axis accelerometer

    NASA Technical Reports Server (NTRS)

    Paik, H. J.

    1990-01-01

    A new superconducting accelerometer, capable of measuring both linear and angular accelerations, is under development at the University of Maryland. A single superconducting proof mass is magnetically levitated against gravity or any other proof force. Its relative positions and orientations with respect to the platform are monitored by six superconducting inductance bridges sharing a single amplifier, called the Superconducting Quantum Interference Device (SQUID). The six degrees of freedom, the three linear acceleration components and the three angular acceleration components, of the platform are measured simultaneously. In order to improve the linearity and the dynamic range of the instrument, the demodulated outputs of the SQUID are fed back to appropriate levitation coils so that the proof mass remains at the null position for all six inductance bridges. The expected intrinsic noise of the instrument is 4 x 10(exp -12)m s(exp -2) Hz(exp -1/2) for linear acceleration and 3 x 10(exp -11) rad s(exp -2) Hz(exp -1/2) for angular acceleration in 1-g environment. In 0-g, the linear acceleration sensitivity of the superconducting accelerometer could be improved by two orders of magnitude. The design and the operating principle of a laboratory prototype of the new instrument is discussed.

  3. Interplay Between Ferromagnetism and Superconductivity

    NASA Astrophysics Data System (ADS)

    Linder, Jacob; Sudbø, Asle

    This chapter presents results on transport properties of hybrid structures where the interplay between ferromagnetism and superconductivity plays a central role. In particular, the appearance of so-called odd-frequency pairing in such structures is investigated in detail. The basic physics of superconductivity in such structures is presented, and the quasiclassical theory of Greens functions with appropriate boundary conditions is given. Results for superconductor∣ferromagnet bilayers as well as magnetic Josephson junctions and spin valves are presented. Further phenomena that are studied include transport in the presence of inhomogenous magnetic textures, spin-Josephon effect, and crossed Andreev reflection. We also investigate the possibility of intrinsic coexistence of ferromagnetism and superconductivity, as reported in a series of uranium-based heavy-fermion compounds. The nature of such a coexistence and the resulting superconducting order parameter is discussed along with relevant experimental results. We present a thermodynamic treatment for a model of a ferromagnetic supercondcutor and moreover suggest ways to experimentally determine the pairing symmetry of the superconducting gap, in particular by means of conductance spectroscopy.

  4. Fast superconducting magnetic field switch

    DOEpatents

    Goren, Yehuda; Mahale, Narayan K.

    1996-01-01

    The superconducting magnetic switch or fast kicker magnet is employed with electron stream or a bunch of electrons to rapidly change the direction of flow of the electron stream or bunch of electrons. The apparatus employs a beam tube which is coated with a film of superconducting material. The tube is cooled to a temperature below the superconducting transition temperature and is subjected to a constant magnetic field which is produced by an external dc magnet. The magnetic field produced by the dc magnet is less than the critical field for the superconducting material, thus, creating a Meissner Effect condition. A controllable fast electromagnet is used to provide a magnetic field which supplements that of the dc magnet so that when the fast magnet is energized the combined magnetic field is now greater that the critical field and the superconducting material returns to its normal state allowing the magnetic field to penetrate the tube. This produces an internal field which effects the direction of motion and of the electron stream or electron bunch. The switch can also operate as a switching mechanism for charged particles.

  5. Fast superconducting magnetic field switch

    DOEpatents

    Goren, Y.; Mahale, N.K.

    1996-08-06

    The superconducting magnetic switch or fast kicker magnet is employed with electron stream or a bunch of electrons to rapidly change the direction of flow of the electron stream or bunch of electrons. The apparatus employs a beam tube which is coated with a film of superconducting material. The tube is cooled to a temperature below the superconducting transition temperature and is subjected to a constant magnetic field which is produced by an external dc magnet. The magnetic field produced by the dc magnet is less than the critical field for the superconducting material, thus, creating a Meissner Effect condition. A controllable fast electromagnet is used to provide a magnetic field which supplements that of the dc magnet so that when the fast magnet is energized the combined magnetic field is now greater that the critical field and the superconducting material returns to its normal state allowing the magnetic field to penetrate the tube. This produces an internal field which effects the direction of motion and of the electron stream or electron bunch. The switch can also operate as a switching mechanism for charged particles. 6 figs.

  6. Variation in superconducting transition temperature due to tetragonal domains in two-dimensionally doped SrTiO3

    NASA Astrophysics Data System (ADS)

    Noad, Hilary; Spanton, Eric M.; Nowack, Katja C.; Inoue, Hisashi; Kim, Minu; Merz, Tyler A.; Bell, Christopher; Hikita, Yasuyuki; Xu, Ruqing; Liu, Wenjun; Vailionis, Arturas; Hwang, Harold Y.; Moler, Kathryn A.

    2016-11-01

    Strontium titanate is a low-temperature, non-Bardeen-Cooper-Schrieffer superconductor that superconducts to carrier concentrations lower than in any other system and exhibits avoided ferroelectricity at low temperatures. Neither the mechanism of superconductivity in strontium titanate nor the importance of the structure and dielectric properties for the superconductivity are well understood. We studied the effects of twin structure on superconductivity in a 5.5-nm-thick layer of niobium-doped SrTiO3 embedded in undoped SrTiO3. We used a scanning superconducting quantum interference device susceptometer to image the local diamagnetic response of the sample as a function of temperature. We observed regions that exhibited a superconducting transition temperature Tc≳ 10 % higher than the temperature at which the sample was fully superconducting. The pattern of these regions varied spatially in a manner characteristic of structural twin domains. Some regions are too wide to originate on twin boundaries; therefore, we propose that the orientation of the tetragonal unit cell with respect to the doped plane affects Tc. Our results suggest that the anisotropic dielectric properties of SrTiO3 are important for its superconductivity and need to be considered in any theory of the mechanism of the superconductivity.

  7. Variation in superconducting transition temperature due to tetragonal domains in two-dimensionally doped SrTiO3

    DOE PAGES

    Noad, Hilary; Spanton, Eric M.; Nowack, Katja C.; ...

    2016-11-28

    Strontium titanate is a low-temperature, non–Bardeen-Cooper-Schrieffer superconductor that superconducts to carrier concentrations lower than in any other system and exhibits avoided ferroelectricity at low temperatures. Neither the mechanism of superconductivity in strontium titanate nor the importance of the structure and dielectric properties for the superconductivity are well understood. We studied the effects of twin structure on superconductivity in a 5.5-nm-thick layer of niobium-doped SrTiO3 embedded in undoped SrTiO3. We used a scanning superconducting quantum interference device susceptometer to image the local diamagnetic response of the sample as a function of temperature. We observed regions that exhibited a superconducting transition temperaturemore » Tc ≳ 10% higher than the temperature at which the sample was fully superconducting. The pattern of these regions varied spatially in a manner characteristic of structural twin domains. Some regions are too wide to originate on twin boundaries; therefore, we propose that the orientation of the tetragonal unit cell with respect to the doped plane affects Tc. Finally, our results suggest that the anisotropic dielectric properties of SrTiO3 are important for its superconductivity and need to be considered in any theory of the mechanism of the superconductivity.« less

  8. Superconducting PM undiffused machines with stationary superconducting coils

    DOEpatents

    Hsu, John S.; Schwenterly, S. William

    2004-03-02

    A superconducting PM machine has a stator, a rotor and a stationary excitation source without the need of a ferromagnetic frame which is cryogenically cooled for operation in the superconducting state. PM material is placed between poles on the rotor to prevent leakage or diffusion of secondary flux before reaching the main air gap, or to divert PM flux where it is desired to weaken flux in the main air gap. The PM material provides hop-along capability for the machine in the event of a fault condition.

  9. 4. MESOSCOPIC SUPERCONDUCTIVITY: Proximity Action theory of superconductive nanostructures

    NASA Astrophysics Data System (ADS)

    Skvortsov, M. A.; Larkin, A. I.; Feigel'man, M. V.

    2001-10-01

    We review a novel approach to the superconductive proximity effect in disordered normal-superconducting (N-S) structures. The method is based on the multicharge Keldysh action and is suitable for the treatment of interaction and fluctuation effects. As an application of the formalism, we study the subgap conductance and noise in two-dimensional N-S systems in the presence of the electron-electron interaction in the Cooper channel. It is shown that singular nature of the interaction correction at large scales leads to a nonmonotonuos temperature, voltage and magnetic field dependence of the Andreev conductance.

  10. Space applications of superconductivity - Digital electronics

    NASA Technical Reports Server (NTRS)

    Harris, R. E.

    1980-01-01

    Superconducting electronics offers a variety of remarkable properties including high speed and low dissipation. The paper discusses fundamental considerations which appear to suggest that superconducting (cryogenic) technology will offer significant advantages for future digital devices. It shows how the active element in superconducting electronics, the Josephson junction, works and discusses the technology for fabricating the devices. The characteristics of published circuits are briefly reviewed, and the capabilities of future superconducting computers and instruments are projected.

  11. Superconductive articles including cerium oxide layer

    DOEpatents

    Wu, Xin D.; Muenchausen, Ross E.

    1993-01-01

    A ceramic superconductor comprising a metal oxide substrate, a ceramic high temperature superconductive material, and a intermediate layer of a material having a cubic crystal structure, said layer situated between the substrate and the superconductive material is provided, and a structure for supporting a ceramic superconducting material is provided, said structure comprising a metal oxide substrate, and a layer situated over the surface of the substrate to substantially inhibit interdiffusion between the substrate and a ceramic superconducting material deposited upon said structure.

  12. Irreversibility line and flux pinning properties in a multilayered cuprate superconductor of Ba2Ca3Cu4O8(O,F)2 (Tc = 105 K)

    NASA Astrophysics Data System (ADS)

    Shirage, P. M.; Iyo, A.; Shivagan, D. D.; Tanaka, Y.; Kito, H.; Kodama, Y.

    2008-07-01

    Irreversibility line (IL) and flux pinning properties were investigated for a Ba2Ca3Cu4O8(O,F)2 (F-0234) multilayered cuprate superconductor with a Tc of 105 K. The intragrain critical current density (Jc) and irreversibility field (Birr) were determined by using Bean's critical state model for the grain-aligned sample (nominal composition Ba2Ca3Cu4O8.7F1.3). The irreversibility line (IL) of F-0234 is much lower than that of (Cu,C)Ba2Ca3Cu4Oy ((Cu, C)-1234) and HgBa2Ca3Cu4Oy (Hg-1234) in spite of the spacing between the superconducting blocks of F-0234 (7.3 Å) being much thinner. The double logarithmic plot of Birr field versus [1-(T/Tc) ] analysis hints that the flux line melting model has been adopted. An anisotropy factor of 65 was calculated from a 3D to 2D crossover field of about 0.95 T. Due to the high anisotropy of this system, a low IL has resulted. The flux pinning force density Fp ( ≈JcB) exhibits scaling behaviour when the magnetic field B is normalized by the Birr field. Analysis of the normalized pinning force reveals that a surface pinning mechanism is dominant and the reduced magnetic field bmax = 0.2 agrees with surface pinning mechanism with closely spaced pins.

  13. Superconducting Metallic Glass Transition-Edge-Sensors

    NASA Technical Reports Server (NTRS)

    Hays, Charles C. (Inventor)

    2013-01-01

    A superconducting metallic glass transition-edge sensor (MGTES) and a method for fabricating the MGTES are provided. A single-layer superconducting amorphous metal alloy is deposited on a substrate. The single-layer superconducting amorphous metal alloy is an absorber for the MGTES and is electrically connected to a circuit configured for readout and biasing to sense electromagnetic radiation.

  14. Superconducting wire with improved strain characteristics

    DOEpatents

    Luhman, T.; Klamut, C.J.; Suenaga, M.; Welch, D.

    1979-12-19

    A superconducting wire comprising a superconducting filament and a beryllium strengthened bronze matrix in which the addition of beryllium to the matrix permits a low volume matrix to exhibit reduced elastic deformation after heat treating which increases the compression of the superconducting filament on cooling and thereby improve the strain characteristics of the wire.

  15. Superconducting wire with improved strain characteristics

    DOEpatents

    Luhman, Thomas; Klamut, Carl J.; Suenaga, Masaki; Welch, David

    1982-01-01

    A superconducting wire comprising a superconducting filament and a beryllium strengthened bronze matrix in which the addition of beryllium to the matrix permits a low volume matrix to exhibit reduced elastic deformation after heat treating which increases the compression of the superconducting filament on cooling and thereby improve the strain characteristics of the wire.

  16. Superconducting wire with improved strain characteristics

    DOEpatents

    Luhman, Thomas; Klamut, Carl J.; Suenaga, Masaki; Welch, David

    1982-01-01

    A superconducting wire comprising a superconducting filament and a beryllium strengthened bronze matrix in which the addition of beryllium to the matrix permits a low volume matrix to exhibit reduced elastic deformation after heat treating which increases the compression of the superconducting filament on cooling and thereby improves the strain characteristics of the wire.

  17. Crystal growth and annealing study of fragile, non-bulk superconductivity in YFe2Ge 2

    DOE PAGES

    Kim, H.; Ran, S.; Mun, E. D.; ...

    2015-02-05

    In this study, we investigated the occurrence and nature of superconductivity in single crystals of YFe2Ge2 grown out of Sn flux by employing X-ray diffraction, electrical resistivity and specific heat measurements. We found that the residual resistivity ratio (RRR) of single crystals can be greatly improved, reaching as high as ~60, by decanting the crystals from the molten Sn at ~350°C and/or by annealing at temperatures between 550°C and 600°C. We found that the samples with RRR ≳ 34 showed resistive signatures of superconductivity with the onset of the superconducting transition Tc ≈ 1.4K. RRR values vary between 35 andmore » 65 with, on average, no systematic change in value Tc, indicating that the systematic changes in RRR do not lead to comparable changes in Tc. Specific heat measurements on samples that showed the clear resistive signatures of a superconducting transition did not show any signature of a superconducting phase transition, which suggests that the superconductivity observed in this compound is either some sort of filamentary, strain-stabilized superconductivity associated with small amounts of stressed YFe2Ge2 (perhaps at twin boundaries or dislocations) or is a second crystallographic phase that is present at level below detection capability of conventional powder X-ray techniques.« less

  18. Effect of superconductivity on near-field radiative heat transfer

    NASA Astrophysics Data System (ADS)

    Králík, Tomáš; Musilová, Věra; Fořt, Tomáš; Srnka, Aleš

    2017-02-01

    Near-field (NF) radiative heat transfer (RHT) over vacuum space between bodies can exceed the far-field (FF) heat transfer by orders of magnitude. A large portion of the heat flux transferred between metals in NF is at very low frequencies, much lower than in FF. Thus a strong effect of superconductivity on NF RHT can be expected even at radiation temperatures above the superconducting critical temperature, where nearly no effect in FF is observed. We have examined experimentally the RHT between plane-parallel surfaces of niobium. Up to a fivefold decrease in NF heat flux was observed when the colder sample passed from the normal to the superconducting state. We found that a maximum decrease occurs at sample spacings ten times shorter than the spacing of crossover between the NF and FF heat flux, being ≈1000/T (μm). Applying Polder's and Van Hove's relations for NF RHT and BCS theory of superconductivity, we explain this effect and show the roles of transversal electric and magnetic modes in the steep decrease of heat flux below the critical temperature and the subsequent flux saturation at low temperatures.

  19. Strain tolerant microfilamentary superconducting wire

    DOEpatents

    Finnemore, Douglas K.; Miller, Theodore A.; Ostenson, Jerome E.; Schwartzkopf, Louis A.; Sanders, Steven C.

    1993-02-23

    A strain tolerant microfilamentary wire capable of carrying superconducting currents is provided comprising a plurality of discontinuous filaments formed from a high temperature superconducting material. The discontinuous filaments have a length at least several orders of magnitude greater than the filament diameter and are sufficiently strong while in an amorphous state to withstand compaction. A normal metal is interposed between and binds the discontinuous filaments to form a normal metal matrix capable of withstanding heat treatment for converting the filaments to a superconducting state. The geometry of the filaments within the normal metal matrix provides substantial filament-to-filament overlap, and the normal metal is sufficiently thin to allow supercurrent transfer between the overlapped discontinuous filaments but is also sufficiently thick to provide strain relief to the filaments.

  20. Superconducting Storage Cavity for RHIC

    SciTech Connect

    Ben-Zvi,I.

    2009-01-02

    This document provides a top-level description of a superconducting cavity designed to store hadron beams in the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory. It refers to more detailed documents covering the various issues in designing, constructing and operating this cavity. The superconducting storage cavity is designed to operate at a harmonic of the bunch frequency of RHIC at a relatively low frequency of 56 MHz. The current storage cavities of RHIC operate at 197 MHz and are normal-conducting. The use of a superconducting cavity allows for a high gap voltage, over 2 MV. The combination of a high voltage and low frequency provides various advantages stemming from the resulting large longitudinal acceptance bucket.

  1. Sensing with Superconducting Point Contacts

    PubMed Central

    Nurbawono, Argo; Zhang, Chun

    2012-01-01

    Superconducting point contacts have been used for measuring magnetic polarizations, identifying magnetic impurities, electronic structures, and even the vibrational modes of small molecules. Due to intrinsically small energy scale in the subgap structures of the supercurrent determined by the size of the superconducting energy gap, superconductors provide ultrahigh sensitivities for high resolution spectroscopies. The so-called Andreev reflection process between normal metal and superconductor carries complex and rich information which can be utilized as powerful sensor when fully exploited. In this review, we would discuss recent experimental and theoretical developments in the supercurrent transport through superconducting point contacts and their relevance to sensing applications, and we would highlight their current issues and potentials. A true utilization of the method based on Andreev reflection analysis opens up possibilities for a new class of ultrasensitive sensors. PMID:22778630

  2. Sensing with superconducting point contacts.

    PubMed

    Nurbawono, Argo; Zhang, Chun

    2012-01-01

    Superconducting point contacts have been used for measuring magnetic polarizations, identifying magnetic impurities, electronic structures, and even the vibrational modes of small molecules. Due to intrinsically small energy scale in the subgap structures of the supercurrent determined by the size of the superconducting energy gap, superconductors provide ultrahigh sensitivities for high resolution spectroscopies. The so-called Andreev reflection process between normal metal and superconductor carries complex and rich information which can be utilized as powerful sensor when fully exploited. In this review, we would discuss recent experimental and theoretical developments in the supercurrent transport through superconducting point contacts and their relevance to sensing applications, and we would highlight their current issues and potentials. A true utilization of the method based on Andreev reflection analysis opens up possibilities for a new class of ultrasensitive sensors.

  3. Intermediate superconductive magnetic energy storage

    SciTech Connect

    Masuda, M.; Fujino, H.; Iwamoto, M.; Murakomi, M.; Shintomi, T.; Veda, K.

    1983-05-01

    In the past decade, the superconducting magnetic energy storage (SMES) for application to peak shaving in utility has been investigated in a manner to construct the huge superconducting coil in bed rock. To confine the strong electromagnetic forces accompanied with the high magnetic field, megaton structures, no matter how they will be constructed in a liquid helium temperature, are needed. To meet such a requirement, the revolutionary idea was proposed that the superconducting coil would be constructed on the underground bed rock. Here presented is a 10 MWh unit as an intermediate SMES that is a milestone along the distant way of RandD of SMES against 1,000 - 10,000 MWh unit which advocate the replacement of the hydro-pumped station. Therefore, even if the 10 MWh unit would not function as a storage in the utility network, its design should also consider the same situation.

  4. Spin/orbital and magnetic quantum number selective magnetization measurements for CoFeB/MgO multilayer films

    NASA Astrophysics Data System (ADS)

    Yamazoe, M.; Kato, T.; Suzuki, K.; Adachi, M.; Shibayama, A.; Hoshi, K.; Itou, M.; Tsuji, N.; Sakurai, Y.; Sakurai, H.

    2016-11-01

    Spin selective magnetic hysteresis (SSMH) curves, orbital selective magnetic hysteresis (OSMH) curves and magnetic quantum number selective SSMH curves are obtained for CoFeB/MgO multilayer films by combining magnetic Compton profile measurements and superconducting quantum interference device (SQUID) magnetometer measurements. Although the SQUID magnetometer measurements do not show perpendicular magnetic anisotropy (PMA) in the CoFeB/MgO multilayer film, PMA behavior is observed in the OSMH and SSMH curves for the |m|  =  2 magnetic quantum number states. These facts indicate that magnetization switching behavior is dominated by the orbital magnetization of the |m|  =  2 magnetic quantum number states.

  5. Spin/orbital and magnetic quantum number selective magnetization measurements for CoFeB/MgO multilayer films.

    PubMed

    Yamazoe, M; Kato, T; Suzuki, K; Adachi, M; Shibayama, A; Hoshi, K; Itou, M; Tsuji, N; Sakurai, Y; Sakurai, H

    2016-11-02

    Spin selective magnetic hysteresis (SSMH) curves, orbital selective magnetic hysteresis (OSMH) curves and magnetic quantum number selective SSMH curves are obtained for CoFeB/MgO multilayer films by combining magnetic Compton profile measurements and superconducting quantum interference device (SQUID) magnetometer measurements. Although the SQUID magnetometer measurements do not show perpendicular magnetic anisotropy (PMA) in the CoFeB/MgO multilayer film, PMA behavior is observed in the OSMH and SSMH curves for the |m|  =  2 magnetic quantum number states. These facts indicate that magnetization switching behavior is dominated by the orbital magnetization of the |m|  =  2 magnetic quantum number states.

  6. Tuning anomalous Hall effect in perpendicular multilayers with different oxygen environment by interfacial ionic migration

    NASA Astrophysics Data System (ADS)

    Zhang, J. Y.; Sun, Q. Y.; Liu, Y. W.; Peng, W. L.; Wang, F. M.; Pan, Y. D.; Ding, L.; Yu, G. H.

    2017-02-01

    Interfacial oxygen migration and its induced anomalous Hall effect are reported in perpendicular multilayers with different interfacial oxygen-coordinated. Saturation Hall resistance RAH for Pt/Co/MgO/Pt and Pt/Co/Al2O3/Pt multilayers is 3.66 Ω and 4.34 Ω in as-deposited state, respectively. After annealing at 400 °C, RAH value reaches 4.82 Ω and 6.67 Ω, which is 32% and 54% larger than that in as-deposited samples, respectively. Especially, the increment value ΔRAH in Pt/Co/Al2O3/Pt multilayers is 101% larger than that in Pt/Co/MgO/Pt film. Interfacial structural analysis shows such differentΔRAH in two samples originates from distinct oxygen migration behavior induced different interfacial oxygen-coordinated.

  7. Dual anisotropic character in Fe/Pt multilayer grown on (001) MgO substrate

    SciTech Connect

    Pandey, Himanshu; Rakshit, R. K.; Gupta, Anurag; Maurya, K. K.; Dalai, M. K.; Budhani, R. C.

    2014-04-24

    The multilayers of [Fe(5Å)/Pt(25 Å)]{sub ×15} were prepared by dc magnetron sputtering on 50 Å Pt-buffered MgO substrates. The structural characterization of the multilayers was carried out using X-ray diffraction, X-ray reflectivity. The Secondary ion mass spectroscopy measurement reveals the depth profile and compositional modulations of the multilayer films as per our design specifications. Room temperature magnetic measurements were carried out by using SQUID both in-plane and out-of-plane sample geometry. Magnetization measurements show similar M-H loops for both in-plane and out-of-plane directions of external magnetic field with a coercivity of 190 Oe. These measurements indicate that our samples are magnetically soft and have multifunctional character which is important for making magnetic tunnel junctions.

  8. High-efficiency diffractive x-ray optics from sectioned multilayers

    SciTech Connect

    Kang, H C; Stephenson, G B; Liu, C; Conley, R; Macrander, A T; Maser, J; Bajt, S; Chapman, H N

    2004-12-14

    We investigate the diffraction properties of sectioned multilayers in Laue (transmission) geometry, at hard x-ray energies (9.5 and 19.5 keV). Two samples are studied, a 200 period W/Si multilayer of 29 nm d-spacing, and a 2020 period Mo/Si multilayer of 7 nm d-spacing, with cross-section depths ranging from 2 to 17 {micro}m. Rocking curves across the Bragg reflections exhibit well-defined interference fringes originating from the depth of the sample. Efficiencies as high as 70% were obtained. This exceeds the theoretical limit for standard zone plates operating in the multi-beam regime, demonstrating that all of the intensity can be directed into a single diffraction order in small-period structures.

  9. Multilayer porous structures of HVPE and MOCVD grown GaN for photonic applications

    NASA Astrophysics Data System (ADS)

    Braniste, T.; Ciers, Joachim; Monaico, Ed.; Martin, D.; Carlin, J.-F.; Ursaki, V. V.; Sergentu, V. V.; Tiginyanu, I. M.; Grandjean, N.

    2017-02-01

    In this paper we report on a comparative study of electrochemical processes for the preparation of multilayer porous structures in hydride vapor phase epitaxy (HVPE) and metal organic chemical vapor phase deposition (MOCVD) grown GaN. It was found that in HVPE-grown GaN, multilayer porous structures are obtained due to self-organization processes leading to a fine modulation of doping during the crystal growth. However, these processes are not totally under control. Multilayer porous structures with a controlled design have been produced by optimizing the technological process of electrochemical etching in MOCVD-grown samples, consisting of five pairs of thin layers with alternating-doping profiles. The samples have been characterized by SEM imaging, photoluminescence spectroscopy, and micro-reflectivity measurements, accompanied by transfer matrix analysis and simulations by a method developed for the calculation of optical reflection spectra. We demonstrate the applicability of the produced structures for the design of Bragg reflectors.

  10. Process for making a multilayer interconnect system

    NASA Technical Reports Server (NTRS)

    Zachry, Clyde L. (Inventor); Niedzwiecke, Andrew J. (Inventor)

    1976-01-01

    A process for making an interconnect system for a multilayer circuit pattern. The interconnect system is formed having minimized through-hole space consumption so as to be suitable for high density, closely meshed circuit patterns.

  11. Fabrication of wedged multilayer Laue lenses

    SciTech Connect

    Prasciolu, M.; Leontowich, A. F. G.; Krzywinski, J.; Andrejczuk, A.; Chapman, H. N.; Bajt, S.

    2015-01-01

    We present a new method to fabricate wedged multilayer Laue lenses, in which the angle of diffracting layers smoothly varies in the lens to achieve optimum diffracting efficiency across the entire pupil of the lens. This was achieved by depositing a multilayer onto a flat substrate placed in the penumbra of a straight-edge mask. The distance between the mask and the substrate was calibrated and the multilayer Laue lens was cut in a position where the varying layer thickness and the varying layer tilt simultaneously satisfy the Fresnel zone plate condition and Bragg’s law for all layers in the stack. This method can be used to extend the achievable numerical aperture of multilayer Laue lenses to reach considerably smaller focal spot sizes than achievable with lenses composed of parallel layers.

  12. Fabrication of wedged multilayer Laue lenses

    DOE PAGES

    Prasciolu, M.; Leontowich, A. F. G.; Krzywinski, J.; ...

    2015-01-01

    We present a new method to fabricate wedged multilayer Laue lenses, in which the angle of diffracting layers smoothly varies in the lens to achieve optimum diffracting efficiency across the entire pupil of the lens. This was achieved by depositing a multilayer onto a flat substrate placed in the penumbra of a straight-edge mask. The distance between the mask and the substrate was calibrated and the multilayer Laue lens was cut in a position where the varying layer thickness and the varying layer tilt simultaneously satisfy the Fresnel zone plate condition and Bragg’s law for all layers in the stack.more » This method can be used to extend the achievable numerical aperture of multilayer Laue lenses to reach considerably smaller focal spot sizes than achievable with lenses composed of parallel layers.« less

  13. Microwave study of superconducting Sn films above and below percolation

    NASA Astrophysics Data System (ADS)

    Beutel, Manfred H.; Ebensperger, Nikolaj G.; Thiemann, Markus; Untereiner, Gabriele; Fritz, Vincent; Javaheri, Mojtaba; Nägele, Jonathan; Rösslhuber, Roland; Dressel, Martin; Scheffler, Marc

    2016-08-01

    The electronic properties of superconducting Sn films ({T}{{c}}≈ 3.8 {{K}}) change significantly when reducing the film thickness down to a few {nm}, in particular close to the percolation threshold. The low-energy electrodynamics of such Sn samples can be probed via microwave spectroscopy, e.g. with superconducting stripline resonators. Here we study Sn thin films, deposited via thermal evaporation—ranging in thickness between 38 and 842 {nm}—which encompasses the percolation transition. We use superconducting Pb stripline resonators to probe the microwave response of these Sn films in a frequency range between 4 and 20 {GHz} at temperatures from 7.2 down to 1.5 {{K}}. The measured quality factor of the resonators decreases with rising temperature due to enhanced losses. As a function of the sample thickness we observe three regimes with significantly different properties: samples below percolation, i.e. ensembles of disconnected superconducting islands, exhibit dielectric properties with negligible losses, demonstrating that macroscopic current paths are required for appreciable dynamical conductivity of Sn at GHz frequencies. Thick Sn films, as the other limit, lead to low-loss resonances both above and below T c of Sn, as expected for bulk conductors. But in an intermediate thickness regime, just above percolation and with labyrinth-like morphology of the Sn, we observe a quite different behavior: the superconducting state has a microwave response similar to the thicker, completely covering films with low microwave losses; but the metallic state of these Sn films is so lossy that resonator operation is suppressed completely.

  14. Four-junction superconducting circuit

    NASA Astrophysics Data System (ADS)

    Qiu, Yueyin; Xiong, Wei; He, Xiao-Ling; Li, Tie-Fu; You, J. Q.

    2016-06-01

    We develop a theory for the quantum circuit consisting of a superconducting loop interrupted by four Josephson junctions and pierced by a magnetic flux (either static or time-dependent). In addition to the similarity with the typical three-junction flux qubit in the double-well regime, we demonstrate the difference of the four-junction circuit from its three-junction analogue, including its advantages over the latter. Moreover, the four-junction circuit in the single-well regime is also investigated. Our theory provides a tool to explore the physical properties of this four-junction superconducting circuit.

  15. Superconductivity: Anatomy of a Discovery

    NASA Astrophysics Data System (ADS)

    Pesic, Peter

    2011-04-01

    The discovery of superconductivity in 1911 by Heike Kamerlingh Onnes and his collaborators, though unexpected, rested on thirty years of prior work perfecting and applying the techniques of low temperature physics. His achievements reflected both his experimental skill and his close study of theory. The comparison with his competitors (especially James Dewar) reveals the effects of personal style, awareness of human nature, and organizational skill. That the actual first detection of superconductivity was made by a young assistant, Gilles Holst, raise deep questions of authorship, priority, and recognition.

  16. Stripes and superconductivity in cuprates

    NASA Astrophysics Data System (ADS)

    Tranquada, John M.

    2012-06-01

    Holes doped into the CuO2 planes of cuprate parent compounds frustrate the antiferromagnetic order. The development of spin and charge stripes provides a compromise between the competing magnetic and kinetic energies. Static stripe order has been observed only in certain particular compounds, but there are signatures which suggest that dynamic stripe correlations are common in the cuprates. Though stripe order is bad for superconducting phase coherence, stripes are compatible with strong pairing. Ironically, magnetic-field-induced stripe order appears to enhance the stability of superconducting order within the planes.

  17. Freely oriented portable superconducting magnet

    DOEpatents

    Schmierer, Eric N.; Prenger, F. Coyne; Hill, Dallas D.

    2010-01-12

    A freely oriented portable superconducting magnet is disclosed. Coolant is supplied to the superconducting magnet from a repository separate from the magnet, enabling portability of the magnet. A plurality of support assemblies structurally anchor and thermally isolate the magnet within a thermal shield. A plurality of support assemblies structurally anchor and thermally isolate the thermal shield within a vacuum vessel. The support assemblies restrain movement of the magnet resulting from energizing and cooldown, as well as from changes in orientation, enabling the magnet to be freely orientable.

  18. Exploring Novel Forms of Superconductivity

    DTIC Science & Technology

    2012-10-19

    REPORT FINALPROJECT REPORT: W911NF-08-1-0196 “EXPLORING NOVEL FORMS OF SUPERCONDUCTIVITY ....” 14. ABSTRACT 16. SECURITY CLASSIFICATION OF: Novel...Rev 8/98) Prescribed by ANSI Std. Z39.18 - 30-Jun-2011 FINALPROJECT REPORT: W911NF-08-1-0196 “EXPLORING NOVEL FORMS OF SUPERCONDUCTIVITY ...publications (other than abstracts): Received Paper 12/24/2009 1.00 Jian Liu, M. Kareev, S. Prosandeev, B. Gray, P. Ryan, J.W. Freeland, J. Chakhalian. Effect

  19. A Planar Two-Dimensional Superconducting Bolometer Array for the Green Bank Telescope

    NASA Technical Reports Server (NTRS)

    Benford, Dominic; Staguhn, Johannes G.; Chervenak, James A.; Chen, Tina C.; Moseley, S. Harvey; Wollack, Edward J.; Devlin, Mark J.; Dicker, Simon R.; Supanich, Mark

    2004-01-01

    In order to provide high sensitivity rapid imaging at 3.3mm (90GHz) for the Green Bank Telescope - the world's largest steerable aperture - a camera is being built by the University of Pennsylvania, NASA/GSFC, and NRAO. The heart of this camera is an 8x8 close-packed, Nyquist-sampled detector array. We have designed and are fabricating a functional superconducting bolometer array system using a monolithic planar architecture. Read out by SQUID multiplexers, the superconducting transition edge sensors will provide fast, linear, sensitive response for high performance imaging. This will provide the first ever superconducting bolometer array on a facility instrument.

  20. A planar two-dimensional superconducting bolometer array for the Green Bank Telescope

    NASA Astrophysics Data System (ADS)

    Benford, Dominic J.; Dicker, Simon R.; Wollack, Edward J.; Supanich, Mark P.; Staguhn, Johannes G.; Moseley, S. H., Jr.; Irwin, Kent D.; Devlin, Mark J.; Chervenak, James A.; Chen, Tina C.

    2004-10-01

    In order to provide high sensitivity rapid imaging at 3.3 mm (90 GHz) for the Green Bank Telescope - the world's largest steerable aperture - a camera is being built by the University of Pennsylvania, NASA/GSFC, and NRAO. The heart of this camera is an 8x8 close-packed, Nyquist-sampled detector array. We have designed and are fabricating a functional superconducting bolometer array system using a monolithic planar architecture. Read out by SQUID multiplexers, the superconducting transition edge sensors will provide fast, linear, sensitive response for high performance imaging. This will provide the first ever superconducting bolometer array on a facility instrument.