WorldWideScience

Sample records for a-15 superconducting compounds

  1. Superconducting properties and the structural transition in compounds with the A-15 lattice

    Energy Technology Data Exchange (ETDEWEB)

    Gor' kov, L.P.; Dorokhov, O.N.

    1976-11-01

    The dependence of T/sub c/ on composition and strain is computed and compared with the corresponding dependence of T/sub m/. It is shown that the superconducting and structural properties of the A-15 compounds can be described, at least qualitatively, in the quasi-one-dimensional model previously developed by the authors. It is assumed that the superconductivity mechanism is analogous to that of the BCS theory. The upper critical field, H/sub c//sub 2/, of the V/sub 3/Si and Nb/sub 3/Sn compounds turns out to be much higher than that of V or Nb.

  2. Atomic ordering, phase stability and superconductivity in bulk and filamentary A15 type compounds

    International Nuclear Information System (INIS)

    Fluekiger, R.

    1987-05-01

    The influence of atomic ordering effects and ordering kinetics on the superconducting and metallurgical properties of A15 type compounds are critically discussed based on own and literature data. First, the techniques for determining the order parameter are reviewed. The dependence of T c vs. S in various A15 type compounds as a function of the quenching temperature and of the high energy particle irradiation fluence is discussed. A model for the disordering mechanism in A15 compounds is established, based on the new concept of the virtual lattice site. It is shown that the disordering mechanism is the same in both cases, high temperature heat treatment and high energy particle irradiation. The very complete representation of ordering effects also contains the variation of other properties, e.g. γ, θ D , ρ o and B c2 (0). Furthermore, it allows to draw empirical correlations between atomic ordering and A15 phase stability. Finally, it is shown on selected examples that the optimization of the critical current density at high fields in Nb 3 Sn wires by alloying is nothing else than a consequence of the occurrence of perfect atomic ordering in binary Nb 3 Sn. (orig.)

  3. Alteration of the superconducting properties of A15 compounds and elementary composite superconductors by non-hydrostatic elastic strain

    International Nuclear Information System (INIS)

    Welch, D.O.

    1979-01-01

    Elastic strains alter (usually, but not always, adversely) the critical temperatures, magnetic fields, and current densities of superconducting A15 compounds; non-hydrostatic strain states are particularly effective in this regard. This paper is a review of the experimental evidence, obtained by a variety of techniques, concerning the strain dependence of the critical properties of a number of A15 compounds and a discussion of theoretical models for describing such effects

  4. Irradiation defects in the A-15 compounds V3Si and Nb3Ge: effects on superconducting and transport properties

    International Nuclear Information System (INIS)

    Rullier-Albenque, F.

    1984-11-01

    In the first part the mechanisms of atomic displacements under electron irradiation in these diatomic ordered solids are studied. In the case of superconducting alloys, simultaneous measurements of electrical resistivity at 20 K and critical temperature allow to distinguish the influence of point defects created in each sub-lattice and antisite defects. The threshold energies have been determined. In the case of V 3 Si, Frenkel pairs have been characterized by their specific resistivities and the decrease of Tsub(c) by vanadium vacancies. The Tsub(c) results obtained on V 3 Si also reveal the existence of a threshold electron energy to produce antisite defects. The second part is a comparative study of irradiation effects in Nb 3 Ge with very different kinds of projectiles: 2.5 MeV electrons, fast neutrons or 100 MeV heavy ions (uranium fission fragments). For these three types of irradiation, resistivity and critical temperature damage can be described in terms of point defects: Frenkel pairs and antisite defects. In the third part we have studied the influence of 2.5 MeV electron or fission fragment-irradiation on the resistivity versus temperature curves of Nb 3 Ge. For both projectiles, negative temperature coefficients of resistivity drho)/dT, were measured and correlated with resistivity at 280 K and 25 K. These anomalous transport properties are related to an electron localization process assisted by electron-phonon and electron-electron interaction [fr

  5. Superconductivity in graphite intercalation compounds

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Robert P. [Cavendish Laboratory, University of Cambridge, Madingley Road, Cambridge CB3 0HE (United Kingdom); Weller, Thomas E.; Howard, Christopher A. [Department of Physics & Astronomy, University College of London, Gower Street, London WCIE 6BT (United Kingdom); Dean, Mark P.M. [Department of Condensed Matter Physics and Materials Science, Brookhaven National Laboratory, Upton, NY 11973 (United States); Rahnejat, Kaveh C. [Department of Physics & Astronomy, University College of London, Gower Street, London WCIE 6BT (United Kingdom); Saxena, Siddharth S. [Cavendish Laboratory, University of Cambridge, Madingley Road, Cambridge CB3 0HE (United Kingdom); Ellerby, Mark, E-mail: mark.ellerby@ucl.ac.uk [Department of Physics & Astronomy, University College of London, Gower Street, London WCIE 6BT (United Kingdom)

    2015-07-15

    Highlights: • Historical background of graphite intercalates. • Superconductivity in graphite intercalates and its place in the field of superconductivity. • Recent developments. • Relevant modeling of superconductivity in graphite intercalates. • Interpretations that pertain and questions that remain. - Abstract: The field of superconductivity in the class of materials known as graphite intercalation compounds has a history dating back to the 1960s (Dresselhaus and Dresselhaus, 1981; Enoki et al., 2003). This paper recontextualizes the field in light of the discovery of superconductivity in CaC{sub 6} and YbC{sub 6} 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 these relate 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.

  6. Ceramic/metal and A15/metal superconducting composite materials exploiting the superconducting proximity effect and method of making the same

    International Nuclear Information System (INIS)

    Holcomb, M.J.

    1999-01-01

    A composite superconducting material made of coated particles of ceramic superconducting material and a metal matrix material is disclosed. The metal matrix material fills the regions between the coated particles. The coating material is a material that is chemically nonreactive with the ceramic. Preferably, it is silver. The coating serves to chemically insulate the ceramic from the metal matrix material. The metal matrix material is a metal that is susceptible to the superconducting proximity effect. Preferably, it is a NbTi alloy. The metal matrix material is induced to become superconducting by the superconducting proximity effect when the temperature of the material goes below the critical temperature of the ceramic. The material has the improved mechanical properties of the metal matrix material. Preferably, the material consists of approximately 10% NbTi, 90% coated ceramic particles (by volume). Certain aspects of the material and method will depend upon the particular ceramic superconductor employed. An alternative embodiment of the invention utilizes A15 compound superconducting particles in a metal matrix material which is preferably a NbTi alloy

  7. Ceramic/metal and A15/metal superconducting composite materials exploiting the superconducting proximity effect and method of making the same

    Science.gov (United States)

    Holcomb, Matthew J.

    1999-01-01

    A composite superconducting material made of coated particles of ceramic superconducting material and a metal matrix material. The metal matrix material fills the regions between the coated particles. The coating material is a material that is chemically nonreactive with the ceramic. Preferably, it is silver. The coating serves to chemically insulate the ceramic from the metal matrix material. The metal matrix material is a metal that is susceptible to the superconducting proximity effect. Preferably, it is a NbTi alloy. The metal matrix material is induced to become superconducting by the superconducting proximity effect when the temperature of the material goes below the critical temperature of the ceramic. The material has the improved mechanical properties of the metal matrix material. Preferably, the material consists of approximately 10% NbTi, 90% coated ceramic particles (by volume). Certain aspects of the material and method will depend upon the particular ceramic superconductor employed. An alternative embodiment of the invention utilizes A15 compound superconducting particles in a metal matrix material which is preferably a NbTi alloy.

  8. Nature of the defects in irradiated A-15 compounds

    International Nuclear Information System (INIS)

    Pande, C.S.; Viswanathan, R.

    1978-01-01

    From transmission electron microscopy and heat capacity measurements radiation induced damage in A-15 compounds was found to be inhomogeneous, consisting of small disordered regions in an ordered matrix. Some consequences of this result are discussed

  9. A spin echo study of A15 intermetallic compounds

    International Nuclear Information System (INIS)

    Schoep, G.K.

    1976-01-01

    This thesis mainly concerns the measurement of spin-lattice relaxation times in intermetallic compounds of the bcc lattice structure, having the formula V 3 X (C = Pt, Ir, Os, Pd, Rh, Ni, Co, Au). When, in a spin echo experiment, a two-pulse sequence was applied, several quadrupolar echoes were observed. Special attention is given to the 'forbidden' echoes (absol.(Δm')GT1) in V 3 Au and V 3 Co. In relation to the V 3 X compounds, several characteristics are discussed including temperature dependence and concentration dependence of spin relaxation times, superconductivity and the importance of d-state electrons in determination of the spin relaxation times. Finally, the above characteristics were determined for 6 different samples of the vanadium-gold alloy, V 3 Au, specifically

  10. Kinetic study of the formation of the superconducting A15 phase in the Nb-Al-Si system

    International Nuclear Information System (INIS)

    Binh-Phung.

    1978-12-01

    So far, aluminum-containing superconductors showed excellent critical fields and temperatures. Powder Metallurgy shows the most promise in producing these particular kinds of superconductors in the near future. The scope of this research is to apply a kinetic study to observe the behavior of the Nb(Al,Si) system at elevated temperatures. From such observations, an optimized method of obtaining the A15 superconducting phase can be achieved. This study has resulted in a two step heat treatment to obtain the A15 phase. For the primary heat treatment of infiltrated rods, 600 0 C for 11 hours or 650 0 C for 1 hour was found suitable to form a barrier of intermetallic compound around the pores. For the secondary heat treatment, 1700 0 C for 15 seconds resulted in the formation of the A15 superconducting phase with a critical temperature of 18.25 0 K. A15 formation for wires is similar to infiltrated rods. The only difference is the diffusion path which is now much shorter. 600 0 C for 1 hour was found suitable for the primary heat treatment and 1700 0 C for 15 seconds was the most suitable for the secondary heat treatment. The highest critical temperature found thus far was 18.78 0 K

  11. Multiple superconducting phases in heavy fermion compounds ...

    Indian Academy of Sciences (India)

    Here we show that multiple superconducting phases are present in heavy fermion superconductors, CeCoIn5 [2] and PrOs4Sb12 [3] , both of which were discovered very recently. The superconducting gap function of PrOs4Sb12 was investigated using thermal transport measurements in magnetic field rotated relative to the.

  12. Multiple superconducting phases in heavy fermion compounds ...

    Indian Academy of Sciences (India)

    ... that in CeCoIn5 the Fulde-Ferrel-Larkin-Ovchinikov (FFLO) phase, in which the order parameter is spatially modulated and has planar nodes aligned perpendicular to the vortices, appears at low temperature and high field. These results open up a new realm for the study of the superconductivity with multiple phases.

  13. APW--LCAO band model for A15 compounds

    International Nuclear Information System (INIS)

    Mattheiss, L.F.

    1975-01-01

    The results of nonrelativistic augmented-plane-wave (APW) band-structure calculations at symmetry points in the cubic Brillouin zone for V 3 Si, V 3 Ge, Nb 3 Al, and Nb 3 Sn are fit using the Slater-Koster linear-combination-of-atomic-orbitals (LCAO) interpolation scheme. This LCAO model involves Bloch sums formed from 30 A-atom (A = V, Nb) d orbitals and eight B-atom (B = Si, Ge, Al, Sn) s-p orbitals. In its simplest form, this LCAO model fits 73 APW energy eigenvalues at GAMMA, X, M, and R with an rms error of 0.020 to 0.023 Ry by means of 21 two-center parameters. Improved accuracy is achieved, particularly for states near E/sub F/, by weighting these more heavily in the LCAO fit, partially relaxing the two-center approximation, and increasing the number of LCAO parameters to 39. The results of this APW-LCAO model are applied to evaluate the accuracy of the Labbe-Friedel (LF) linear-chain and the Weger-Goldberg (WG) coupled-chain band models for the A15 compounds. It is concluded that (a) corrections to the LF and WG models (about 3 and 1 eV, respectively) are sufficient to wash out fine structure in the density of states on a meV energy scale; (b) there is no evidence for describing the electronic structure of these A15 as one-dimensional or quasi-one-dimensional in character; (c) the density-of-states peak near E/sub F/ involves primarily A-atom d states with delta 1 (x 2 - y 2 ) symmetry, in contrast to the predictions of the LF (delta 1 + delta 2 ) and WG (delta 2 ) models; (d) the accuracy of the present LCAO model is insufficient for predicting the precise shape of the density of states near E/sub F/ from first principles

  14. Superconducting transition temperature and the formation of closed electron shells in the atoms of superconducting compounds

    International Nuclear Information System (INIS)

    Chapnik, I.M.

    1985-01-01

    The relationship between the regularities in the tansition temperature (T/sub c/) values in analogous compounds (having the same structure and stoichiometry) and the formation of the closed electron shells outside inert gas shells in the atoms of the variable component of the 158 intermetallic superconducting compounds has been discussed. The T/sub c/ data for compounds of the elements from the first long period of the Periodic Table (K to Se) are compared with the T/sub c/ data for the analogous compounds of the elements from the second long period (Rb to Te)

  15. Study of superconducting Ba-Ge-Co compounds

    Science.gov (United States)

    Li, Yang; Ross, J. H.; Larrea, J. A.; Baggio-Saitovitch, Elisa

    2004-08-01

    We prepared samples with starting composition Ba 8-Ge 46- x-Co x ( x=0, 4 and 6) by direct melting. These Ge-based compounds were characterized by X-ray diffraction and WDS, and we found two superconducting transitions at TC=10 and 4 K in the Co-free sample. Co-doping results in the suppression of TC to 7 K. The superconducting volume fraction also decreases with increasing Co-doping. For Co-doped samples, there is no 4 K superconducting transition. X-ray refinement shows that the compounds are mixtures of several phases. The dominant phase is diamond Ge, and we found no Ge-clathrate phases. Besides diamond Ge, there are also several weak diffractions from an unknown Ba-Ge phase, and most of them were indexed on the basis of a monoclinic unit cell. Diffraction peaks for Ba 2Ge, BaGe, BaGe 2, BaGe 2O 5, BaGeO 3, Ba 3GeO 5, α-BaGeO 3, BaGe 2O 5, Ba 2Ge 5O 12, β-BaGeO 3, Ba 2GeO 4 and BaGe 4O 9 were carefully searched for but not seen in the samples. For the Co-doped sample, besides the main diamond Ge phase, there is also a semiconducting phase CoGe 2. With increasing Co content, the CoGe 2 content increases. The WDS results agree with this result. The main phase composition for the Co-free sample is Ba 0.01Ge 99.9. We also discuss the origin of two superconducting transitions in Ge-based compounds.

  16. Magnetic and superconducting order in some random pseudobinary compounds

    International Nuclear Information System (INIS)

    Dongen, J.C.M. van.

    1982-01-01

    This thesis presents the results of a study on the magnetic and superconducting ordering phenomena in some random pseudobinary compounds. In the investigations ternary systems are utilised in which two of the elements form a binary intermetallic compound, e.g. PdH, GdCu and YCo 2 . A third element is then randomly substituted into one of the sublattices without changing the basic intermetallic compound structure. In chapter II a study is presented on the Kondo effect and spin-glass freezing of the magnetic impurities Cr, Mn, and Fe in superconducting palladium hydride. Chapter III contains a study on crystal structure transformations and magnetic ordering phenomena in GdCusub(1-x)Gasub(x) and related pseudobinary compounds. In Chapter IV experiments on the magnetic properties and the electrical resistivity of the transition metal Laves phase compounds Y(Cosub(1-x)Fesub(x)) 2 , Y(Irsub(1-x)Fesub(x)) 2 and Hf(Cosub(1-x)Fesub(x)) 2 are described. (Auth.)

  17. Magnetism, superconductivity and Fermi surfaces of plutonium compounds

    International Nuclear Information System (INIS)

    Haga, Y.; Aoki, D.; Yamagami, H.; Matsuda, T.D.; Nakajima, K.; Arai, Y.; Homma, Y.; Shiokawa, Y.; Yamamoto, E.; Nakamura, A.; Onuki, Y.

    2007-01-01

    Single crystals of plutonium compounds PuRhGa 5 and PuIn 3 are successfully grown. For PuRhGa 5 , anisotropy of the superconducting upper critical field was found and analyzed by the anisotropic mass model, consistent with quasi-two-dimensional electronic states predicted by band calculations. On the other hand, the de Haas-van Alphen oscillation was observed in PuIn 3 . By comparing with the band calculations, it is concluded that 5f electrons are itinerant in PuIn 3

  18. Thermal expansion of superconducting fulleride and borocarbide compounds

    International Nuclear Information System (INIS)

    Burkhart, G.J.

    1995-08-01

    In order to detact and analyze thermodynamic phase transitions, the investigation of the thermal expansion via capacitance dilatometry is a powerful experimental technique, due to the extremely high resolution (ΔL/L∝10 -8 -10 -10 ). With respect to the air sensitivity of the fullerides a dilatometer operating under inert atmosphere was designed and the thermal expansion of polycrystalline fulleride (Rb 3 C 60 , K 3 C 60 ) and borocarbide (YNi 2 B 2 C, LuNi 2 B 2 C) compounds was determined in the temperature range 5-320 K. Most effort was focused on a quantitative evaluation of the discontinuity in the thermal expansivity α at the superconducting transition. The results are discussed in the context of the Ehrenfest relation, which connects the jump in the thermal expansivity Δα with the pressure dependence of the superconducting transition temperature dT c /dp and the jump in the specific heat Δc p /T c at the superconducting transition. For Rb 3 C 60 and K 3 C 60 the jump in the specific heat can be derived via the Ehrenfest relation using the results of the thermal expansion measurements and the well-known pressure dependence of the superconducting transition temperature. The derived values for Rb 3 C 60 and K 3 Cu 60 are Δc p /T c ∝75mJ/molK 2 and Δc p /T c ∝64 mJ.molK 2 , respectively. The directly measured specific heat jump of K 3 C 60 gives approximately the same value of Δc p /T c , and, therefore, the use of the Ehrenfest relation on fullerides is justified. The specific heat jumps Δc p /T c , determined from theoretically derived values of the density of states at the Fermi level N(E F ) and the McMillan-parameter λ, exceed the experimental results by a factor of 1.5-2. This finding reflects the uncertainty concerning the superconducting parameters N(E F ) and λ. (orig.)

  19. A-15 superconducting composites in the 0.1 micron region

    Science.gov (United States)

    Finnemore, D.; Verhoeven, J. D.

    1980-05-01

    Consumable electrode arc casting procedures were used to produce 10 kg billets Cu-Nb alloys. The resulting dendrite morphology and homogeneity is suitable for industrial scale production of Nb3Sn-Cu multifilamentary superconducting wire for magnets in the 8 to 14 Telsa range. If proper heat flow patterns can be maintained, the same techniques should be suitable for 100 kg billets. In the design of these composites for magnet wire, a Cu70Nb30 casting is a good choice of Nb content if high J/sub c/ and ease of fabrication are the major considerations. If unusual strain tolerance is the primary consideration, then a lower Nb and lower Sn content is preferred.

  20. Pressure induced Superconductivity in the Charge Density Wave Compound Tritelluride

    Energy Technology Data Exchange (ETDEWEB)

    Hamlin, J.J.; Zocco, D.A.; Sayles, T.A.; Maple, M.B.; /UC, Davis; Chu, J.-H.; Fisher, I.R.; /Stanford U., Geballe Lab.

    2010-02-15

    A series of high-pressure electrical resistivity measurements on single crystals of TbTe{sub 3} reveal a complex phase diagram involving the interplay of superconducting, antiferromagnetic and charge density wave order. The onset of superconductivity reaches a maximum of almost 4 K (onset) near {approx} 12.4 GPa.

  1. Superconductivity

    CERN Document Server

    Poole, Charles P; Farach, Horacio A

    1995-01-01

    Superconductivity covers the nature of the phenomenon of superconductivity. The book discusses the fundamental principles of superconductivity; the essential features of the superconducting state-the phenomena of zero resistance and perfect diamagnetism; and the properties of the various classes of superconductors, including the organics, the buckministerfullerenes, and the precursors to the cuprates. The text also describes superconductivity from the viewpoint of thermodynamics and provides expressions for the free energy; the Ginzburg-Landau and BCS theories; and the structures of the high

  2. Comments on possible preferential order-disorder in A-15 compounds based upon Nb

    International Nuclear Information System (INIS)

    Cox, D.E.

    1977-01-01

    The possible existence of preferential B-site disorder in A-15 compounds recently claimed on the basis of x-ray powder diffraction data but questioned from the viewpoint of known phase diagrams is examined for some Nb-based compounds of this type. It is concluded that x-ray powder data do not allow the determination of both order and compositional variables as suggested, and the latter must therefore be determined by some other method. (author)

  3. Physical and chemical studies of superconduction properties of the intercalation compounds

    International Nuclear Information System (INIS)

    Eder, F.X.; Lerf, A.

    1980-01-01

    The superconducting properties of the intercalation compounds of layered dichalcogenides were studied. Our studies were concerned mainly to the alkali metal intercalation derivatives of TaS 2 and NbS 2 , and later on extended to the molecule intercalation compounds. The main difficulties with this class of superconductors result from varying material properties; these are therefore the subject of broad intensity in our investigations. The results received on the physical and chemical properties of the intercalation compounds is utilized for a phenomenological description of the factors mainly determining there superconducting properties. (orig.) [de

  4. Microscopic superconducting parameters from tunneling in A15 Nb-Sn

    International Nuclear Information System (INIS)

    Rudman, D.A.; Beasley, M.R.

    1984-01-01

    High-quality tunnel junctions have been fabricated on thin films of A15 Nb-Sn (20--25 at. %) using oxidized a-Si tunnel barriers and Pb counterelectrodes. These junctions have been used to measure changes in the gap, the transition temperature T/sub c/, and the tunneling density of states with composition in this important high-T/sub c/ superconductor. With the use of the proximity-effect-modified data reduction scheme developed by Arnold and Wolf, values for α 2 F(ω) and μ( are obtained. As the Sn content approaches stoichiometry, the lowest-energy phonon branch in α 2 F(ω) both increases in weight and shifts to lower energy. These two effects combine to produce the increases in lambda as stoichiometry is approached, and at the same time can account for the observed increase in 2Δ/k/sub B/T/sub c/. The values of μ( remain essentially constant as a function of composition, and hence show no evidence for an increased Coulomb interaction with increasing disorder as recently proposed by Anderson et al

  5. Superconductivity

    International Nuclear Information System (INIS)

    Andersen, N.H.; Mortensen, K.

    1988-12-01

    This report contains lecture notes of the basic lectures presented at the 1st Topsoee Summer School on Superconductivity held at Risoe National Laboratory, June 20-24, 1988. The following lecture notes are included: L.M. Falicov: 'Superconductivity: Phenomenology', A. Bohr and O. Ulfbeck: 'Quantal structure of superconductivity. Gauge angle', G. Aeppli: 'Muons, neutrons and superconductivity', N.F. Pedersen: 'The Josephson junction', C. Michel: 'Physicochemistry of high-T c superconductors', C. Laverick and J.K. Hulm: 'Manufacturing and application of superconducting wires', J. Clarke: 'SQUID concepts and systems'. (orig.) With 10 tabs., 128 figs., 219 refs

  6. Direct observation of defects in A15 compounds produced by fast neutron irradiation

    International Nuclear Information System (INIS)

    Pande, C.S.

    1979-01-01

    The nature of defect or defect complexes produced in superconducting compounds Nb 3 Sn, Nb 3 Pt, and V 3 Si by high energy (E greater than or equal to 1 MeV) neutron irradiation is investigated by transmission electron microscopy. The newly developed technique of superlattice reflection imaging is used whereby the regions of reduced long range order are directly imaged. Unlike metals these regions were found in general not to collapse into dislocation loops. The size and the volume fraction of these disordered regions are obtained for fluences ranging from 10 17 neutrons/cm 2 to 3 x 10 19 neutrons/cm 2 . The size ranges from 20A to 60A. Typical volume fraction for 10 18 neutrons/cm 2 is over 1%

  7. Internal friction due to domain-wall motion in martensitically transformed A15 compounds

    International Nuclear Information System (INIS)

    Snead, C.L. Jr.; Welch, D.O.

    1985-01-01

    A lattice instability in A15 materials in some cases leads to a cubic-to-tetragonal martensitic transformation at low temperatures. The transformed material orients in lamellae with c axes alternately aligned along the directions producing domain walls between the lamellae. An internal-friction (delta) feature below T/sub m/ is attributed to stress-induced domain-wall motion. The magnitude of the friction increases as temperature is lowered below T/sub m/ as (1-c/a) increases, and behaves as (1-c/a) 2 from T/sub m/ down to the superconducting critical temperature where the increasing tetragonality is inhibited. The effect of strain in the lattice is to decrease the domain-wall internal friction, but not affect T/sub m/. Neutron-induced disorder and the addition of some third-elements in alloying decrease both delta and T/sub m/, with some elements reducing only the former. Less than 1 at. % H is seen to completely suppress both delta and T/sub m. Martensitically transformed V 2 Zr demonstrates low-temperature internal-friction and modulus behavior consists with easy β/m wall motion relative to the easy m/m motion of the A15's. For the V 2 Zr, a peak in delta is observed, qualitatively in agreement with expected β/m wall motion

  8. Internal friction due to domain-wall motion in martensitically transformed A15 compounds

    Energy Technology Data Exchange (ETDEWEB)

    Snead, C.L. Jr.; Welch, D.O.

    1985-01-01

    A lattice instability in A15 materials in some cases leads to a cubic-to-tetragonal martensitic transformation at low temperatures. The transformed material orients in lamellae with c axes alternately aligned along the <100> directions producing domain walls between the lamellae. An internal-friction (delta) feature below T/sub m/ is attributed to stress-induced domain-wall motion. The magnitude of the friction increases as temperature is lowered below T/sub m/ as (1-c/a) increases, and behaves as (1-c/a)/sup 2/ from T/sub m/ down to the superconducting critical temperature where the increasing tetragonality is inhibited. The effect of strain in the lattice is to decrease the domain-wall internal friction, but not affect T/sub m/. Neutron-induced disorder and the addition of some third-elements in alloying decrease both delta and T/sub m/, with some elements reducing only the former. Less than 1 at. % H is seen to completely suppress both delta and T/sub m. Martensitically transformed V/sub 2/Zr demonstrates low-temperature internal-friction and modulus behavior consists with easy ..beta../m wall motion relative to the easy m/m motion of the A15's. For the V/sub 2/Zr, a peak in delta is observed, qualitatively in agreement with expected ..beta../m wall motion.

  9. Competition between phonon superconductivity and Kondo screening in mixed valence and heavy fermion compounds

    Science.gov (United States)

    Barzykin, Victor; Gor'Kov, L. P.

    2005-06-01

    We consider competition of the Kondo effect and s -wave superconductivity in heavy fermion and mixed valence superconductors, using the phenomenological approach for the periodic Anderson model. Similar to the well known results for the single-impurity Kondo effect in superconductors, we have found the principal possibility of a reentrant regime of the superconducting transition temperature, Tc , in heavy fermion superconductors in a narrow range of model parameters and concentration of f electrons. Suppression of Tc in mixed valence superconductors is much weaker. Our theory has the most validity in the low-temperature Fermi liquid regime, without reentrant behavior of Tc . To check its applicability, we performed the fit for the x dependence of Tc in Ce1-xLaxRu3Si2 and obtained an excellent agreement with the experimental data, although no reentrance was found in this case. Other experimental data are discussed in the light of our theoretical analysis. In particular, we compare temperatures of the superconducting transition for some known homologs, i.e., the analog periodic lattice compounds with and without f elements. For a few pairs of homologs, superconductivity exists only in the heavy fermion materials, thus confirming the uniqueness of superconductivity mechanisms for the latter. We suggest that for some other compounds, the value of Tc may remain of the same order in the two homologs, if superconductivity originates mainly on some light Fermi surface, but induces a sizable superconducting gap on another Fermi surface, for which hybridization or other heavy fermion effects are more significant. By passing, we cite the old results that show that the jump in the specific heat at the transition reflects the heaviness of carriers on this Fermi surface independently of mechanisms responsible for superconductivity.

  10. Superconductivity and magnetic order in the noncentrosymmetric half-Heusler compound ErPdBi

    NARCIS (Netherlands)

    Pan, Y.; Nikitin, A.M.; Bay, T.V.; Huang, Y.K.; Paulsen, C.; Yan, B.H.; de Visser, A.

    2013-01-01

    We report superconductivity at Tc = 1.22 K and magnetic order at TN = 1.06\\ K in the semimetallic noncentrosymmetric half-Heusler compound ErPdBi. The upper critical field, Bc2, has an unusual quasi-linear temperature variation and reaches a value of 1.6 T for T - 0 . Magnetic order is found below

  11. Superconductivity

    CERN Document Server

    Ketterson, John B

    2008-01-01

    Conceived as the definitive reference in a classic and important field of modern physics, this extensive and comprehensive handbook systematically reviews the basic physics, theory and recent advances in the field of superconductivity. Leading researchers, including Nobel laureates, describe the state-of-the-art in conventional and unconventional superconductors at a particularly opportune time, as new experimental techniques and field-theoretical methods have emerged. In addition to full-coverage of novel materials and underlying mechanisms, the handbook reflects continued intense research into electron-phone based superconductivity. Considerable attention is devoted to high-Tc superconductivity, novel superconductivity, including triplet pairing in the ruthenates, novel superconductors, such as heavy-Fermion metals and organic materials, and also granular superconductors. What’s more, several contributions address superconductors with impurities and nanostructured superconductors. Important new results on...

  12. High temperature superconducting compounds II; Proceedings of the Second Symposium, Anaheim, CA, Feb. 20, 21, 1990

    International Nuclear Information System (INIS)

    Whang, S.H.; Dasgupta, A.; Laibowitz, R.

    1990-01-01

    Various topics relevant to the production and implementation of high-temperature superconducting compounds are highlighted including critical current; texturing; ceramics and novel processing; composites; deformation and consolidation; thin films; microstructures; tapes, filaments, and ribbons; and thermodynamics. The thermally activated flux creep, critical current density and current enhancement in high-temperature superconductors are addressed. Also discussed are the phase stability and microstructure of doped superconductors, mechanical considerations in the processing of high-Tc superconductors, fabrication and application of high current density, high RTc superconducting thin films and devices, the effect of substrate temperature and RF biasing on the composition of sputtered Bi-based superconducting thin films, and optical electron microanalysis of cuprate superconductors. The microstructure dependence of critical current density and fabrication of double-layered ribbons from cuprate are also discussed

  13. Superconductivity in pressurized CeRhG e3 and related noncentrosymmetric compounds

    Science.gov (United States)

    Wang, Honghong; Guo, Jing; Bauer, Eric D.; Sidorov, Vladimir A.; Zhao, Hengcan; Zhang, Jiahao; Zhou, Yazhou; Wang, Zhe; Cai, Shu; Yang, Ke; Li, Aiguo; Li, Xiaodong; Li, Yanchun; Sun, Peijie; Yang, Yi-feng; Wu, Qi; Xiang, Tao; Thompson, J. D.; Sun, Liling

    2018-02-01

    We report the discovery of superconductivity in pressurized CeRhG e3 , a nonsuperconducting member of the isostructural family of noncentrosymmetric heavy-fermion compounds Ce T X3 (T =Co , Rh, Ir and X =Si , Ge). Superconductivity appears in CeRhG e3 at a pressure of 19.6 GPa and the transition temperature TC reaches a maximum value of 1.3 K at 21.5 GPa. This finding provides an opportunity to establish systematic correlations between superconductivity and material properties within this family. Though ambient-pressure unit-cell volumes and critical pressures for superconductivity vary substantially across the series, all family members reach a maximum TCmax at a common (±1.7%) critical cell volume Vcrit, and TCmax at Vcrit increases with increasing spin-orbit coupling strength of the d electrons. These correlations show that substantial Kondo and spin-orbit couplings favor superconductivity in this family, the latter reflecting the role of broken centrosymmetry.

  14. Superconductivity

    CERN Document Server

    Poole, Charles P; Creswick, Richard J; Prozorov, Ruslan

    2014-01-01

    Superconductivity, Third Edition is an encyclopedic treatment of all aspects of the subject, from classic materials to fullerenes. Emphasis is on balanced coverage, with a comprehensive reference list and significant graphics from all areas of the published literature. Widely used theoretical approaches are explained in detail. Topics of special interest include high temperature superconductors, spectroscopy, critical states, transport properties, and tunneling. This book covers the whole field of superconductivity from both the theoretical and the experimental point of view. This third edition features extensive revisions throughout, and new chapters on second critical field and iron based superconductors.

  15. Density of states model for the lattice transformation in A-15 compounds

    International Nuclear Information System (INIS)

    Pietrass, B.; Handstein, A.; Behr, G.

    1980-01-01

    The cubic-tetragonal lattice transformation in A-15 compounds is described by an empirical model in which the density of states function near the Fermi energy is characterized by a two-parametric peak in addition to the constant part. Two types of peak splitting under tetragonal deformation are considered, leading to qualitatively different results about the phase transition. Results are given for the order parameter, the phase stability, the soft elastic modulus, and the paramagnetic spin susceptibility. Comparing with measurements of the magnetic susceptibility of V 3 Si single crystals near the phase transition a better agreement is obtained for a twofold degenerate density of states peak than for a threefold degenerate one. (author)

  16. μSR and NMR study of the superconducting Heusler compound YPd2Sn

    Science.gov (United States)

    Saadaoui, H.; Shiroka, T.; Amato, A.; Baines, C.; Luetkens, H.; Pomjakushina, E.; Pomjakushin, V.; Mesot, J.; Pikulski, M.; Morenzoni, E.

    2013-09-01

    We report on muon-spin rotation and relaxation (μSR) and 119Sn nuclear magnetic resonance (NMR) measurements to study the microscopic superconducting and magnetic properties of the Heusler compound with the highest superconducting transition temperature, YPd2Sn (Tc=5.4 K). Measurements in the vortex state provide the temperature dependence of the effective magnetic penetration depth λ(T) and the field dependence of the superconducting gap Δ(0). The results are consistent with a very dirty s-wave BCS superconductor with a gap Δ(0)=0.85(3) meV, λ(0)=212(1) nm, and a Ginzburg-Landau coherence length ξGL(0)≅23 nm. In spite of its very dirty character, the effective density of condensed charge carriers is high compared to that in the normal state. The μSR data in a broad range of applied fields are well reproduced by taking into account a field-related reduction of the effective superconducting gap. Zero-field μSR measurements, sensitive to the possible presence of very small magnetic moments, do not show any indications of magnetism in this compound.

  17. Strain induced superconductivity in the parent compound BaFe2As2

    Science.gov (United States)

    Engelmann, J.; Grinenko, V.; Chekhonin, P.; Skrotzki, W.; Efremov, D. V.; Oswald, S.; Iida, K.; Hühne, R.; Hänisch, J.; Hoffmann, M.; Kurth, F.; Schultz, L.; Holzapfel, B.

    2013-12-01

    The discovery of superconductivity with a transition temperature, Tc, up to 65 K in single-layer FeSe (bulk Tc=8 K) films grown on SrTiO3 substrates has attracted special attention to Fe-based thin films. The high Tc is a consequence of the combined effect of electron transfer from the oxygen-vacant substrate to the FeSe thin film and lattice tensile strain. Here we demonstrate the realization of superconductivity in the parent compound BaFe2As2 (no bulk Tc) just by tensile lattice strain without charge doping. We investigate the interplay between strain and superconductivity in epitaxial BaFe2As2 thin films on Fe-buffered MgAl2O4 single crystalline substrates. The strong interfacial bonding between Fe and the FeAs sublattice increases the Fe-Fe distance due to the lattice misfit, which leads to a suppression of the antiferromagnetic spin density wave and induces superconductivity with bulk Tc≈10 K. These results highlight the role of structural changes in controlling the phase diagram of Fe-based superconductors.

  18. Superconductivity

    International Nuclear Information System (INIS)

    2007-01-01

    During 2007, a large amount of the work was centred on the ITER project and related tasks. The activities based on low-temperature superconducting (LTS) materials included the manufacture and qualification of ITER full-size conductors under relevant operating conditions, the design of conductors and magnets for the JT-60SA tokamak and the manufacture of the conductors for the European dipole facility. A preliminary study was also performed to develop a new test facility at ENEA in order to test long-length ITER or DEMO full-size conductors. Several studies on different superconducting materials were also started to create a more complete database of superconductor properties, and also for use in magnet design. In this context, an extensive measurement campaign on transport and magnetic properties was carried out on commercially available NbTi strands. Work was started on characterising MgB 2 wire and bulk samples to optimise their performance. In addition, an intense experimental study was started to clarify the effect of mechanical loads on the transport properties of multi-filamentary Nb 3 Sn strands with twisted or untwisted superconducting filaments. The experimental activity on high-temperature superconducting (HTS) materials was mainly focussed on the development and characterisation of YBa 2 Cu 3 O 7-X (YBCO) based coated conductors. Several characteristics regarding YBCO deposition, current transport performance and tape manufacture were investigated. In the framework of chemical approaches for YBCO film growth, a new method, developed in collaboration with the Technical University of Cluj-Napoca (TUCN), Romania, was studied to obtain YBCO film via chemical solution deposition, which modifies the well-assessed metallic organic deposition trifluoroacetate (MOD-TFA) approach. The results are promising in terms of critical current and film thickness values. YBCO properties in films with artificially added pinning sites were characterised in collaboration with

  19. Low temperature kinetic study of the formation of the superconducting A15 phase in the Nb--Al--Ge system

    International Nuclear Information System (INIS)

    Douglas, K.E.

    1978-03-01

    A kinetic study has been made of the reactions occurring in the Nb-Al-Ge system at temperatures below 1000 0 C. This study has resulted in a two step heat treatment prior to the A15 formation reaction to be used to control the A15 formed. It was found that a Ge rich phase can be used to control the diffusion rate of the Al into the Nb. The interface between this barrier phase and the Nb matrix serves as the reaction site for the formation of the A15

  20. Unconventional superconductivity of the heavy fermion compound UNi{sub 2}Al{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Zakharov, Andrey

    2008-07-01

    The heavy fermion compound UNi{sub 2}Al{sub 3} exhibits the coexistence of superconductivity and magnetic order at low temperatures, stimulating speculations about possible exotic Cooper-pairing interaction in this superconductor. However, the preparation of good quality bulk single crystals of UNi{sub 2}Al{sub 3} has proven to be a non-trivial task due to metallurgical problems, which result in the formation of an UAl{sub 2} impurity phase and hence a strongly reduced sample purity. The present work concentrates on the preparation, characterization and electronic properties investigation of UNi{sub 2}Al{sub 3} single crystalline thin film samples. The preparation of thin films was accomplished in a molecular beam epitaxy (MBE) system. (100)-oriented epitaxial thin films of UNi{sub 2}Al{sub 3} were grown on single crystalline YAlO{sub 3} substrates cut in (010)- or (112)-direction. The high crystallographic quality of the samples was proved by several characterisation methods, such as X-ray analysis, RHEED and TEM. To study the magnetic structure of epitaxial thin films resonant magnetic X-ray scattering was employed. The magnetic order of thin the film samples, the formation of magnetic domains with different moment directions, and the magnetic correlation length were discussed. The electronic properties of the UNi{sub 2}Al{sub 3} thin films in the normal and superconducting states were investigated by means of transport measurements. A pronounced anisotropy of the temperature dependent resistivity {rho}(T) was observed. Moreover, it was found that the temperature of the resistive superconducting transition depends on the current direction, providing evidence for multiband superconductivity in UNi{sub 2}Al{sub 3}. The initial slope of the upper critical field H'{sub c2}(T) of the thin film samples suggests an unconventional spin-singlet superconducting state, as opposed to bulk single crystal data. To probe the superconducting gap of UNi{sub 2}Al{sub 3

  1. Competition between magnetism and superconductivity in Eu-based intermetallic compounds

    Science.gov (United States)

    Stavinoha, Macy; Green, Lance; Chan, Julia; Morosan, Emilia

    Eu-based intermetallic compounds present a path to discover new correlated electronic behavior in quantum materials. Reports of superconductivity, intermediate valence behavior, and heavy fermions indicate that Eu-based compounds are promising routes to study the relationship between crystallography and electronic properties. The present work is focused on EuGa4, an antiferromagnet with TN = 16 K isostructural with the tetragonal RT2M2 (R = rare earth, T = transition metal, M = metal or metalloid) family that exhibits heavy fermion behavior and unconventional superconductivity. Single crystals of the doped series (Eu1-xLax)Ga4, (Eu1-xCax)Ga4, and Eu(Ga1-xAlx)4 have been grown using the self-flux method and tested for change in unit cell volume and magnetic susceptibility. Results show that doping with Ca (isoelectronic doping) and La (hole doping) reduce TN to 12.4 K and 2.3 K, respectively, for Ca doping up to x = 0.11 and La doping up to x = 0.74 without an associated change in unit cell volume. The series Eu(Ga1-xAlx)4 has shown incommensurate-to-commensurate magnetic transitions. Future studies will aim to further decrease TN and the unit cell volume using physical pressure and chemical pressure through doping. ICAM, Gordon and Betty Moore Foundation.

  2. Discovery of a Superconducting Cu-Bi Intermetallic Compound by High-Pressure Synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Clarke, Samantha M. [Department of Chemistry, Northwestern University, Evanston IL 60208 USA; Walsh, James P. S. [Department of Chemistry, Northwestern University, Evanston IL 60208 USA; Amsler, Maximilian [Department of Materials Science and Engineering, Northwestern University, Evanston IL 60208 USA; Malliakas, Christos D. [Department of Chemistry, Northwestern University, Evanston IL 60208 USA; Yu, Tony [Center for Advanced Radiation Sources, The University of Chicago, Chicago IL 60637 USA; Goedecker, Stefan [Department of Physics, Universität Basel, Kingelbergstr. 82 4056 Basel Switzerland; Wang, Yanbin [Center for Advanced Radiation Sources, The University of Chicago, Chicago IL 60637 USA; Wolverton, Chris [Department of Materials Science and Engineering, Northwestern University, Evanston IL 60208 USA; Freedman, Danna E. [Department of Chemistry, Northwestern University, Evanston IL 60208 USA

    2016-09-26

    A new intermetallic compound, the first to be structurally identified in the Cu-Bi binary system, is reported. This compound is accessed by high-pressure reaction of the elements. Its detailed characterization, physical property measurements, and ab initio calculations are described. The commensurate crystal structure of Cu11Bi7 is a unique variation of the NiAs structure type. Temperature-dependent electrical resistivity and heat capacity measurements reveal a bulk superconducting transition at Tc=1.36 K. Density functional theory calculations further demonstrate that Cu11Bi7 can be stabilized (relative to decomposition into the elements) at high pressure and temperature. These results highlight the ability of high-pressure syntheses to allow for inroads into heretofore-undiscovered intermetallic systems for which no thermodynamically stable binaries are known.

  3. Discovery of a superconducting Cu-Bi intermetallic compound by high-pressure synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Clarke, Samantha M.; Walsh, James P.S.; Malliakas, Christos D.; Freedman, Danna E. [Northwestern Univ., Evanston, IL (United States). Dept. of Chemistry; Amsler, Maximilian; Wolverton, Chris [Northwestern Univ., Evanston, IL (United States). Dept. of Materials Science and Engineering; Yu, Tony; Wang, Yanbin [Chicago Univ., IL (United States). Center for Advanced Radiation Sources; Goedecker, Stefan [Basel Univ. (Switzerland). Dept. of Physics

    2016-10-17

    A new intermetallic compound, the first to be structurally identified in the Cu-Bi binary system, is reported. This compound is accessed by high-pressure reaction of the elements. Its detailed characterization, physical property measurements, and ab initio calculations are described. The commensurate crystal structure of Cu{sub 11}Bi{sub 7} is a unique variation of the NiAs structure type. Temperature-dependent electrical resistivity and heat capacity measurements reveal a bulk superconducting transition at T{sub c}=1.36 K. Density functional theory calculations further demonstrate that Cu{sub 11}Bi{sub 7} can be stabilized (relative to decomposition into the elements) at high pressure and temperature. These results highlight the ability of high-pressure syntheses to allow for inroads into heretofore-undiscovered intermetallic systems for which no thermodynamically stable binaries are known.

  4. Transport measurements on superconducting iron pnictides and Heusler compounds; Transportmessungen an Supraleitenden Eisenpniktiden und Heusler-Verbindungen

    Energy Technology Data Exchange (ETDEWEB)

    Bombor, Dirk

    2014-09-05

    In this work, results of electronic transport measurements are discussed for superconducting iron pnictides as well as for ferromagnetic Heusler compounds. The iron pnictides are a recently discovered class of high temperature superconductors where magnetism might play a crucial role. While the 122-pnictides show antiferromagnetism and migrate to the superconducting state upon doping, ferromagnetism has been observed in doped LiFeAs. On the other hand, in the undoped state this material shows interesting superconducting properties. Among other properties, Heusler compounds are well known due to their ferromagnetism. Co{sub 2}FeSi, which was investigated in this work, is one of the strongest ferromagnets. Beside this, one predicts this compound to be a half-metallic ferromagnet with completely spin polarized electronic transport where all conducting electrons have the same spin. The here addressed properties can well be investigated with the method of electronic transport measurements, whose results on single crystals are discussed in this work.

  5. Solid-state ionics: Studies of lithium-conducting sulfide glasses and a superconducting oxide compound

    International Nuclear Information System (INIS)

    Ahn, Byung Tae.

    1989-01-01

    The first part of this work studies lithium-conducting sulfide glasses for battery applications, while the second part studies the thermodynamic properties of a superconducting oxide compound by using an oxide electrolyte. Lithium conducting glasses based on the SiS 2 -Li 2 S system are possible solid electrolytes for high-energy-density lithium batteries. The foremost requirement for solid electrolytes is that they should have high ionic conductivities. Unfortunately, most crystalline lithium conductors have low ionic conductivities at room temperature. However, glass ionic conductors show higher ionic conductivities than do crystalline forms of the same material. In addition to higher ionic conductivities, glasses appear to have several advantages over crystalline materials. These advantages include isotropic conductivity, absence of grain boundary effects, ease of glass forming, and the potential for a wide range of stability to oxidizing and reducing conditions. Using pyrolitic graphite-coated quartz ampoules, new ternary compounds and glasses in the SiS 2 -Li 2 S system were prepared. Several techniques were used to characterize the materials: powder x-ray diffraction, differential thermal analysis, differential scanning calorimetry, and AC impedance spectroscopy. The measured lithium conductivity of the sulfide glasses was one of the highest among the known solid lithium conductors. Measuring the equilibrium open circuit voltages assisted in determining the electrochemical stabilities of the ternary compounds and glasses with respect to pure Li. A solid-state ionic technique called oxygen coulometric titration was used to measure the thermodynamic stability, the oxygen stoichiometry, and the effects of the oxygen stoichiometry, and the effects of the oxygen stoichiometry and the cooling rate on superconductivity of the YBa 2 Cu 3 O 7-x compound were investigated

  6. Density of states and T/sub c/ of disordered A15 compounds

    International Nuclear Information System (INIS)

    Ghosh, A.K.; Strongin, M.

    1979-01-01

    In this paper various data for the depression of T/sub c/ and N(O) are presented for a wide class of A15 materials. The question of disorder and the limits on T/sub c/ in these materials are discussed

  7. Structure and properties of alloys of A15 type compounds with carbon

    International Nuclear Information System (INIS)

    Savitskij, E.M.; Efimov, Yu.V.; Myasnikova, E.A.

    1983-01-01

    Microstructure and some properties of the alloys on the base of the phases of A15 type in the V-Si-C, Nb-Si-C, Nb-Sn-C, Nb-Al-C, Nb-Ga-C, V-Ga-C ternary systems are investigated. It is established that in the niobium-rich corners of the A-B-C ternary systems the new ternary conpounds do not form, as a rule, bUt the wide ranges of threephase equilibrium A-A 3 B-C exist. New ternary phases with A15 type structure stabilized with carbon are established only in the Nb-Si-C and V-Al-C systems. Alloying with carbon results in sharp refining of structural components of stable and metastable alloys, promotes transition of the alloys into amorphous state at super fast cooling of the melts as well as increases stability of metastable state of the alloys against tempering. After super fast quenching and tempering Tsub(c) of the ternary alloys close to the A15 phases exceed Tsub(c) of equilibrium samples

  8. New superconducting intercalation compounds of organic five-membered heterocyclic compounds with 2H-tantalum disulfide

    International Nuclear Information System (INIS)

    Hummel, H.U.; Fackler, R.; Remmert, P.

    1992-01-01

    The intercalation compounds TaS 2 (pyrrole) 0.5 (1), TaS 2 (2-methylpyrrole) 0.33 (2), TaS 2 (2,5-dimethylpyrrole) (3), TaS 2 (thiazole) 0.33 (4) and TaS 2 (imidazole) 0.33 (5) are formed readily in closed systems at temperatures up to 200degC. Furane and thiophene show no tendency to intercalate in 2H-TaS 2 . Compounds 2-5 are molecular intercalation species, and deintercalation is finished at 350degC, while in 1 the pyrrole guests have been associated and thermally induced deintercalation proceeds up to 900degC with fragmentation. 1-5 can be indexed on the basis of hexagonal symmetry assuming the space group P6 3 /mmc. In 1 the stacking sequence of the host lattice TaS 2 remains unchanges while in 2, 3 and 5 a transformation from the BaB CaC stacking of 2H-TaS 2 to a sequence AbA AcA occurs. In 4 a stacking CbC BcB like in MoS 2 is realized. 1-5 show superconducting behaviour at low temperatures, 2 exhibits a pronounced metall-semiconductor transition at 220 K. (orig.)

  9. Reclamation of niobium compounds from ionic liquid electrochemical polishing of superconducting radio frequency cavities

    Energy Technology Data Exchange (ETDEWEB)

    Wixtrom, Alex I. [Christopher Newport University, Newport News, VA (United States); Buhler, Jessica E. [Christopher Newport University, Newport News, VA (United States); Reece, Charles E. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Abdel-Fattah, Tarek M. [Christopher Newport University, Newport News, VA (United States)

    2013-06-01

    Recent research has shown that choline chloride (vitamin B4)-based solutions can be used as a greener alternative to acid-based electrochemical polishing solutions. This study demonstrated a successful method for electrochemical deposition of niobium compounds onto the surface of copper substrates using a novel choline chloride-based ionic liquid. Niobium ions present in the ionic liquid solution were dissolved into the solution prior to deposition via electrochemical polishing of solid niobium. A black coating was clearly visible on the surface of the Cu following deposition. This coating was analyzed using scanning electron microscopy (SEM), electron dispersive X-ray spectroscopy (EDX), atomic force microscopy (AFM), and X-ray fluorescence spectroscopy (XRF). This ionic liquid-based electrochemical deposition method effectively recycles previously dissolved niobium from electrochemical polishing of superconducting radio frequency (SRF) cavities.

  10. Magnetic precursor of the pressure-induced superconductivity in Fe-ladder compound

    Science.gov (United States)

    Chi, Songxue; Uwatoko, Yoshiya; Cao, Huibo; Hirata, Yasuyuki; Hashizume, Kazuki; Aoyama, Takuya; Ohgushi, Kenya

    The pressure effects on the antiferromagentic orders in iron-based ladder compounds CsFe2Se3 and BaFe2S3 have been studied using neutron diffraction. With identical crystal structure and similar magnetic structures, the two compounds exhibit highly contrasting magnetic behaviors under moderate external pressures. In CsFe2Se3 the ladders are brought much closer to each other by pressure, but the stripe-type magnetic order shows no observable change. In contrast, the stripe order in BaFe2S3, undergoes a quantum phase transition where an abrupt increase of N e xel temperature by more than 50% occurs at about 1 GPa, accompanied by a jump in the ordered moment. With its spin structure unchanged, BaFe2S3 enters an enhanced magnetic phase that bears the characteristics of an orbital selective Mott phase, which is the true neighbor of superconductivity emerging at higher pressures. Research at Oak Ridge National Laboratorys HFIR was sponsored by the Scientific User Facilities Division, Office of Basic Energy Sciences, U.S. Department of Energy.This work was supported by JSPS KAKENHI Grant Number 16H04019.

  11. Effects of stoichiometric doping in superconducting Bi-O-S compounds

    Science.gov (United States)

    Morice, Corentin; Artacho, Emilio; Dutton, Siân E.; Molnar, Daniel; Kim, Hyeong-Jin; Saxena, Siddharth S.

    2015-04-01

    Newly discovered Bi-O-S compounds remain an enigma in attempts to understand their electronic properties. A recent study of Bi4O4S3 has shown it to be a mixture of two phases, Bi2OS2 and Bi3O2S3, the latter being superconducting (Phelan et al 2013 J. Am. Chem. Soc. 135 5372-4). Using density functional theory, we explore the electronic structure of both the phases and the effect of the introduction of extra BiS2 bilayers. Our results demonstrate that the S2 layers dope the bismuth-sulphur bands and this causes metallisation. The bands at the Fermi level are of clear two-dimensional character. One band manifold is confined to the two adjacent, square-lattice bismuth-sulphur planes, a second manifold is confined to the square lattice of sulphur dimers. We show that the introduction of extra BiS2 bilayers does not influence the electronic structure. Finally, we also show that spin-orbit coupling does not have any significant effect on the states close to the Fermi level at the energy scale considered.

  12. A new proposal to the mechanism of superconductivity. Pt.2: The elemental and compound superconductors

    International Nuclear Information System (INIS)

    Huang Shiming

    2001-01-01

    There are one or more group of potential-well-like lattice sites for hulun electrons to populate in crystals. The hulun electrons predominately select the deepest and well-shaped wells to populate, and then, the shallower. The population in each group of sites may be full, partial or empty, decided by the offering of hulun electrons. Hulun electrons in each group are in similar circumstance and in same state. They are correlated. They would establish their collective potential and will act as a whole, if no external disturbances or with minor disturbance but collective effect is in predominance. Hulun electrons in different groups are non-correlated. As the external disturbances are increasing the hulun electron groups will collapse one by one from the lower to higher stabilization. The superconducting temperature TC is the one that the most stabilized hulun electron group is in collapsing when the temperature is the only disturbance factor. This proposal is tested by the experimental results published for elemental and compound superconductors

  13. Study of the superconducting compound Hg,Re-1223 by X-Ray diffraction with application of Rietveld method

    International Nuclear Information System (INIS)

    Putvinskis, Rodrigo

    2008-01-01

    The objective of this work was to study the crystal structure of the superconductor compound of nominal composition Hg 0,82 Re 0,18 Ba 2 Ca 2 Cu 3 O 8+δ and general formula Hg,Re- 1223 and different oxygen contents, by the X-ray diffraction technique, by using the Rietveld method. The studied samples present different oxygen stoichiometry because during the synthesis process, had been heat treated under different oxygen/argon gas mixtures in the ratios: 5:95, 10:90 and 15:85. The results of structural refinement for the samples show that different oxygen contents imply in different cell parameters, atomic positions and distances for the main phase of each sample. The segregation of two superconducting phases with the same crystal structure, but slightly different cell parameters was confirmed for the studied samples both by Rietveld analysis and anomalous X-ray diffraction experiments. It was also confirmed that one of the segregated phases does not incorporate Re cations its composition. The main phase, who incorporates the Re cations, is here called Hg,Re-1223 and the Re-free secondary phase is called Hg- 1223. It was found that the superconducting phases present different crystallite sizes and the sample treated under gas flow composed of 10% oxygen and 90% argon presents the highest fraction of superconducting phases. From these results it was possible to conclude that the sample produced from the precursor compound treated under flow of O 2 /Ar gas at the ratio 10/90 presents the better results for the synthesis of this superconducting compound. (author)

  14. Exploration of stable compounds, crystal structures, and superconductivity in the Be-H system

    Directory of Open Access Journals (Sweden)

    Shuyin Yu

    2014-10-01

    Full Text Available Using first-principles variable-composition evolutionary methodology, we explored the high-pressure structures of beryllium hydrides between 0 and 400 GPa. We found that BeH2 remains the only stable compound in this pressure range. The pressure-induced transformations are predicted as I b a m → P 3 ̄ m 1 → R 3 ̄ m → C m c m → P 4 / n m m , which occur at 24, 139, 204 and 349 GPa, respectively. P 3 ̄ m 1 and R 3 ̄ m structures are layered polytypes based on close packings of H atoms with Be atoms filling all octahedral voids in alternating layers. Cmcm and P4/nmm contain two-dimensional triangular networks with each layer forming a kinked slab in the ab-plane. P 3 ̄ m 1 and R 3 ̄ m are semiconductors while Cmcm and P4/nmm are metallic. We have explored superconductivity of both metal phases, and found large electron-phonon coupling parameters of λ = 0.63 for Cmcm with a Tc of 32.1-44.1 K at 250 GPa and λ = 0.65 for P4/nmm with a Tc of 46.1-62.4 K at 400 GPa. The dependence of Tc on pressure indicates that Tc initially increases to a maximum of 45.1 K for Cmcm at 275 GPa and 97.0 K for P4/nmm at 365 GPa, and then decreases with increasing pressure for both phases.

  15. High pressure superconductivity in iron-based layered compounds studied using designer diamonds.

    Science.gov (United States)

    Tsoi, Georgiy; Stemshorn, Andrew K; Vohra, Yogesh K; Wu, Phillip M; Hsu, F C; Huang, Y L; Wu, M K; Yeh, K W; Weir, Samuel T

    2009-06-10

    High pressure superconductivity in iron-based superconductor FeSe(0.5)Te(0.5) has been studied up to 15 GPa and 10 K using an eight probe designer diamond anvil in a diamond anvil cell device. Four probe electrical resistance measurements show the onset of superconductivity (T(c)) at 14 K at ambient pressure with T(c) increasing with increasing pressure to 19 K at a pressure of 3.6 GPa. At higher pressures beyond 3.6 GPa, T(c) decreases and extrapolation suggests non-superconducting behavior above 10 GPa. The loss of superconductivity coincides with the pressure induced disordering of the Fe(SeTe)(4) tetrahedra reported at 11 GPa in x-ray diffraction studies at ambient temperature.

  16. Magnetic ordering at low temperatures in some random superconducting and insulating compounds

    International Nuclear Information System (INIS)

    Hueser, D.

    1985-01-01

    This thesis presents the results of some investigations on the magnetic ordering phenomena in some random superconducting and insulating materials. The results are described of an investigation of the coexistence of superconductivity and random magnetic freezing in (Th,Nd)Ru 2 . On the basis of various measurements as function of temperature and external magnetic field the author found that spin glass-like freezing can occur far below the superconductivity and even that a sample may re-enter the superconducting state below a freezing temperature. Associated with the isothermal remanent magnetization of a random magnetic material he observed strong anomalies in the critical field versus temperature curves. Also a magnetic field memory effect has been found. (Auth.)

  17. A new disordering mechanism in A15 type compounds submitted to low temperature irradiation or to quenching from high temperatures

    International Nuclear Information System (INIS)

    Fluekiger, R.

    1984-05-01

    A new diffusion mechanism describing the changes of the long range order parameter in A15 type compounds after both quenching from high temperatures or low temperature irradiation with high energy particles is presented. It is based on the occupation of nonequilibrium or 'virtual' sites centered halfway between two neighbouring A atoms on 6c sites, arising from the instability of a single 6c vacancy recently found by Welch and coworkers by pair potential calculations. After low temperature irradiation, the occupation of this interstitial site creates the necessary conditions for A B site exchanges over several interatomic distances by focused replacement collision sequences. Due to the occupation of a certain concentration of virtual sites, atomic 'overlapping' is not only possible between A atoms on the chains or between A and B atoms (due to deviations from perfect ordering),but also between B atoms on BBB sequences. The latter are retained after low temperature irradiation only and are responsible for the observed lattice expansion and static displacement. (orig.) [de

  18. Superconducting gap structure of heavy-Fermion compound URu2Si2 determined by angle-resolved thermal conductivity

    Science.gov (United States)

    Kasahara, Y.; Shishido, H.; Shibauchi, T.; Haga, Y.; Matsuda, T. D.; Onuki, Y.; Matsuda, Y.

    2009-05-01

    In heavy-Fermion compound URu2Si2, unusual superconductivity is embedded in an enigmatic 'hidden order' phase. Recently, it has been shown that URu2Si2 is essentially a multiband superconductor associated with the semimetallic compensated electronic structure. Here, to pin down the detailed superconducting gap structure, we have performed thermal transport measurements on ultraclean URu2Si2 single crystals in magnetic fields rotating various directions relative to the crystal axes. By changing the amplitude of magnetic fields, we determined the nodal topology of electron and hole band separately. The results indicate a new type of unconventional superconductivity with two distinct gaps, in which horizontal line nodes lie within the basal ab plane of the light-hole band with small gap and point nodes along the c-axis in the heavy electron band with large gap. This gap structure is consistent with 'chiral' d-wave symmetry with a form {\\hat{k}}_{z}({\\hat{k}}_{x}+i{\\hat{k}}_{y}) .

  19. Superconducting gap structure of heavy-Fermion compound URu2Si2 determined by angle-resolved thermal conductivity

    International Nuclear Information System (INIS)

    Kasahara, Y; Shishido, H; Shibauchi, T; Matsuda, Y; Haga, Y; Matsuda, T D; Onuki, Y

    2009-01-01

    In heavy-Fermion compound URu 2 Si 2 , unusual superconductivity is embedded in an enigmatic 'hidden order' phase. Recently, it has been shown that URu 2 Si 2 is essentially a multiband superconductor associated with the semimetallic compensated electronic structure. Here, to pin down the detailed superconducting gap structure, we have performed thermal transport measurements on ultraclean URu 2 Si 2 single crystals in magnetic fields rotating various directions relative to the crystal axes. By changing the amplitude of magnetic fields, we determined the nodal topology of electron and hole band separately. The results indicate a new type of unconventional superconductivity with two distinct gaps, in which horizontal line nodes lie within the basal ab plane of the light-hole band with small gap and point nodes along the c-axis in the heavy electron band with large gap. This gap structure is consistent with 'chiral' d-wave symmetry with a form k-circumflex z (k-circumflex x +ik-circumflex y ).

  20. On possibility origination of superconductivity in MgB sub 2 compound

    CERN Document Server

    Zajtsev, R O

    2001-01-01

    The mechanism of originating superconductivity in the MgB sub 2 is studied on the basis of the Hubbard generalized model. The possibility of existence of the Cooper instability in the system with jumps between the cations and anions of the nontransient elements is established with application of the notion on the strong interaction. Filling of the boron four electron p-shell and the magnesium two-electron 3s sup 2 shell is considered with an account of the hexagonal symmetry of the MgB sub 2 elementary cell. The phase diagram of existing the superconductivity in dependence on the filling rate of the (n sub p)p sup 6 and (n sub s)s sup 2 -shells of the nontransient elements is plotted

  1. Magnetic and structural features of RNi2B2C and RNiBC (R=Er, Ho, Dy, Tb, Gd) superconducting compounds

    OpenAIRE

    Baggio-Saitovitch, E. M.; Sánchez, D. R.; Micklitz, H.

    2002-01-01

    Temperature dependent Mössbauer spectroscopy on 57Fe doped (1 at % of Ni) RNi2B2C and RNiBC provided clear evidence of a pair-breaking field at the Ni site for non-superconducting compounds. This field is not present in the superconducting collinear AF DyNi2B2C, however it appears when this compound is diluted with non-magnetic Lu (Dy1-xLu xNi2B2C). Important local information on the spin structure of the R magnetic moments is obtained for both systems. The local symmetries of RNi2B2C and RNi...

  2. Superconducting properties of Zr1+xNi2-xGa and Zr1-xNi2+xGa Heusler compounds

    Directory of Open Access Journals (Sweden)

    Saad Alzahrani

    2017-05-01

    Full Text Available The superconducting properties of a series of Zr1+xNi2-xGa and Zr1-xNi2+xGa compounds have been investigated by x-ray diffraction, electrical resistivity, dc magnetization, and ac susceptibility measurements. While the parent compound, ZrNi2Ga, exhibited the cubic L21 Heusler structure, multiple non-cubic structures formed in the Zr and Ni rich doped materials. For x ≤ 0.3, all Zr1-xNi2+xGa compounds demonstrated superconducting behavior, but no superconductivity was observed in the Zr1+xNi2-xGa alloys for x > 0.2. The magnetization data revealed that all materials in both Zr1+xNi2-xGa and Zr1-xNi2+xGa series exhibited type-II superconductivity. With increasing doping concentration x, the paramagnetic ordering were enhanced in both systems while the superconducting properties were found to weaken. The observations are discussed considering the structural disorders in the systems.

  3. Characterizations of power loads on divertor targets for type-I, compound and small ELMs in the EAST superconducting tokamak

    DEFF Research Database (Denmark)

    Wang, L.; Xu, G.S.; Guo, H.Y.

    2013-01-01

    -III ELMy H-modes. The energy loss and divertor power load are systematically characterized for these different ELMy H-modes to provide a physics basis for the next-step high-power long-pulse operations in EAST. Both type-I and compound ELMs exhibit good confinement (H98(y,2) ∼ 1). A significant loss......The Experimental Advanced Superconducting Tokamak (EAST) has recently achieved a variety of H-mode regimes with different edge-localized mode (ELM) dynamics, including type-I ELMs, compound ELMs, which are manifested by the onset of a large spike followed by a sequence of small spikes on Dα......-III ELMs. It is remarkable that the new very small ELMy H-modes exhibit even lower target power deposition than type-III ELMs, with the peak heat flux generally below 1 MW m−2. These very small ELMs are usually accompanied by broadband fluctuations with frequencies ranging from 20 to 50 kHz, which may...

  4. Electronic Correlations, Jahn-Teller Distortions and Mott Transition to Superconductivity in Alkali-C60 Compounds

    Directory of Open Access Journals (Sweden)

    Alloul H.

    2012-03-01

    Full Text Available The discovery in 1991 of high temperature superconductivity (SC in A3C60 compounds, where A is an alkali ion, has been rapidly ascribed to a BCS mechanism, in which the pairing is mediated by on ball optical phonon modes. While this has lead to consider that electronic correlations were not important in these compounds, further studies of various AnC60 with n=1, 2, 4 allowed to evidence that their electronic properties cannot be explained by a simple progressive band filling of the C60 six-fold degenerate t1u molecular level. This could only be ascribed to the simultaneous influence of electron correlations and Jahn-Teller Distortions (JTD of the C60 ball, which energetically favour evenly charged C60 molecules. This is underlined by the recent discovery of two expanded fulleride Cs3C60 isomeric phases which are Mott insulators at ambient pressure. Both phases undergo a pressure induced first order Mott transition to SC with a (p, T phase diagram displaying a dome shaped SC, a common situation encountered nowadays in correlated electron systems. NMR experiments allowed us to study the magnetic properties of the Mott phases and to evidence clear deviations from BCS expectations near the Mott transition. So, although SC involves an electron-phonon mechanism, the incidence of electron correlations has an importance on the electronic properties, as had been anticipated from DMFT calculations.

  5. Superconductivity in the actinides

    International Nuclear Information System (INIS)

    Smith, J.L.; Lawson, A.C.

    1985-01-01

    The trends in the occurrence of superconductivity in actinide materials are discussed. Most of them seem to show simple transition metal behavior. However, the superconductivity of americium proves that the f electrons are localized in that element and that ''actinides'' is the correct name for this row of elements. Recently the superconductivity of UBe 13 and UPt 3 has been shown to be extremely unusual, and these compounds fall in the new class of compounds now known as heavy fermion materials

  6. Synthesis of molybdenum carbide superconducting compounds by microwave-plasma chemical vapor deposition

    Science.gov (United States)

    Zhao, Hongyang; Cai, Kang; Ma, Zhibin; Cheng, Zhenxiang; Jia, Tingting; Kimura, Hideo; Fu, Qiuming; Tao, Hong; Xiong, Liwei

    2018-02-01

    A method to synthesize molybdenum carbides has been developed based on microwave plasma treatment with methane and hydrogen mixed gases, using a microwave-plasma chemical vapor deposition device. The device framework and its mechanism are described in detail. Two-dimensional α-Mo2C has been directly synthesized by a plate-to-plate substrate holder structure with a microwave power of 920 W and a partial pressure of 20 kPa. In-situ optical emission spectroscopy was used to measure the radical types in the plasma ball during glow discharge. The as-grown α-Mo2C samples were characterized by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy and Raman spectroscopy to determine their phases, purity and chemical groups. The superconducting transition temperature was measured, and the transition temperatures of the relevant phases are discussed in detail. The results confirmed that this method is an efficient way to obtain molybdenum carbides and inspire new research interest in transition metal carbides, which have many intrinsic local properties and applications.

  7. High temperature superconductivity: Concept, preparation and testing of high Tc superconductor compounds, and applications

    International Nuclear Information System (INIS)

    Harara, Wafik

    1992-06-01

    Many studies have been carried out on high temperature superconductors with transition temperature above that of the liquid nitrogen. In this scientific study the concept and the mechanism of this phenomena are discussed, in addition the examples of preparation and testing of high temperature superconductors compounds are shown. Also the most important applications in industry are explained. (author). 15 refs., 2 tabs., 18 figs

  8. Process for optimization of superconductivity properties of YBa2Cu307-δ compounds

    International Nuclear Information System (INIS)

    Perrin, A.M.Y.; Pena-Alvarez, O.; Perrin, C.; Sergent, M.; Le Traon, J.Y.

    1988-01-01

    After obtention the YBaCu0 compound (where Y can be replaced partially or completely by Sc and/or Ba by Sr) is thermally treated in the temperature range 360-500 0 C in an atmosphere containing oxygen [fr

  9. Superconductivity above 90K in the Y-Ba-Cu-O compound system

    International Nuclear Information System (INIS)

    Paterno, G.; Balestrino, G.; Barbanera, S.

    1987-01-01

    Preliminary results on high Tc superconductors are reported. One of Y-Ba-Cu-O compound system has been fabricated. The temperature dependence of the resistance has been determined. The critical temperature of the samples annealed in Oxygen atmosphere is well above the normal boiling point of liquid nitrogen

  10. Superconducting material development

    Science.gov (United States)

    1987-09-01

    A superconducting compound was developed that showed a transition to a zero-resistance state at 65 C, or 338 K. The superconducting material, which is an oxide based on strontium, barium, yttrium, and copper, continued in the zero-resistance state similar to superconductivity for 10 days at room temperature in the air. It was also noted that measurements of the material allowed it to observe a nonlinear characteristic curve between current and voltage at 65 C, which is another indication of superconductivity. The research results of the laboratory experiment with the superconducting material will be published in the August edition of the Japanese Journal of Applied Physics.

  11. Anti-plasmodial activity of Dicoma tomentosa (Asteraceae and identification of urospermal A-15-O-acetate as the main active compound

    Directory of Open Access Journals (Sweden)

    Jansen Olivia

    2012-08-01

    Full Text Available Abstract Background Natural products could play an important role in the challenge to discover new anti-malarial drugs. In a previous study, Dicoma tomentosa (Asteraceae was selected for its promising anti-plasmodial activity after a preliminary screening of several plants traditionally used in Burkina Faso to treat malaria. The aim of the present study was to further investigate the anti-plasmodial properties of this plant and to isolate the active anti-plasmodial compounds. Methods Eight crude extracts obtained from D. tomentosa whole plant were tested in vitro against two Plasmodium falciparum strains (3D7 and W2 using the p-LDH assay (colorimetric method. The Peters’ four-days suppressive test model (Plasmodium berghei-infected mice was used to evaluate the in vivo anti-plasmodial activity. An in vitro bioguided fractionation was undertaken on a dichloromethane extract, using preparative HPLC and TLC techniques. The identity of the pure compound was assessed using UV, MS and NMR spectroscopic analysis. In vitro cytotoxicity against WI38 human fibroblasts (WST-1 assay and haemolytic activity were also evaluated for extracts and pure compounds in order to check selectivity. Results The best in vitro anti-plasmodial results were obtained with the dichloromethane, diethylether, ethylacetate and methanol extracts, which exhibited a high activity (IC50 ≤ 5 μg/ml. Hot water and hydroethanolic extracts also showed a good activity (IC50 ≤ 15 μg/ml, which confirmed the traditional use and the promising anti-malarial potential of the plant. The activity was also confirmed in vivo for all tested extracts. However, most of the active extracts also exhibited cytotoxic activity, but no extract was found to display any haemolytic activity. The bioguided fractionation process allowed to isolate and identify a sesquiterpene lactone (urospermal A-15-O-acetate as the major anti-plasmodial compound of the plant (IC50 Conclusions The present study

  12. Absence of low energy magnetic spin-fluctuations in isovalently and aliovalently doped LaCo2B2 superconducting compounds

    Science.gov (United States)

    Majumder, M.; Ghoshray, A.; Khuntia, P.; Mazumdar, C.; Poddar, A.; Baenitz, M.; Ghoshray, K.

    2016-09-01

    Magnetization, resistivity and 11B, 59Co NMR measurements have been performed on the Pauli paramagnet \\text{LaC}{{\\text{o}}2}{{\\text{B}}2} , and the superconductors \\text{L}{{\\text{a}}0.9}{{\\text{Y}}0.1}\\text{C}{{\\text{o}}2}{{\\text{B}}2} ({{T}\\text{c}}≈ 4.2 K) and \\text{La}{{≤ft(\\text{C}{{\\text{o}}0.7}\\text{F}{{\\text{e}}0.3}\\right)}2}{{\\text{B}}2} ({{T}\\text{c}}≈ 5.8 K). The site selective NMR experiment reveals the multiband nature of the Fermi surface in these systems. The temperature independent Knight shift and 1/T 1 T clearly indicate the absence of correlated low energy magnetic spin-fluctuations in the normal state, which is in contrast to other Fe-based pnictides. The density of states (DOS) of Co 3d electrons has been enhanced in superconducting \\text{L}{{\\text{a}}0.9}{{\\text{Y}}0.1}\\text{C}{{\\text{o}}2}{{\\text{B}}2} and \\text{La}{{≤ft(\\text{C}{{\\text{o}}0.7}\\text{F}{{\\text{e}}0.3}\\right)}2}{{\\text{B}}2} with respect to the non superconducting reference compound \\text{LaC}{{\\text{o}}2}{{\\text{B}}2} . The occurrence of superconductivity is related to the DOS enhancement.

  13. Superconductivity, structures, ESR and SIMS-analysis of a high-Tc Y0.33Ba0.67Cu2.33O3.67-σ compound

    International Nuclear Information System (INIS)

    Porjesz, T.; Bankuti, J.; Karman, T.

    1987-10-01

    In a new kind of high-T c Y 0.33 Ba 0.67 Cu 2.33 O 3.67-σ compound the superconducting transition comes into being between 92 and 84 K, the value of Meissner state is 68 vol.%, the change in ESR signal provides a possible proof for superconductivity, the main phase has an orthorhombic symmetry and the SIMS analysis offers quite new and valuable information on the material components. (author). 10 refs, 6 figs

  14. Metallurgy of continuous filamentary A15 superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Suenaga, M

    1980-01-01

    The early history of the bronze process is recapitulated and modifications to the process which have since followed are described. The metallurgical principles, which are involved in the process, are described including the kinetics of the compound growth, the effects of additives on the growth, etc. The superconducting properties of these compounds are also discussed. The influence of metallurgical variables on the superconducting properties is discussed in detail. In discussing the superconducting current densities in these compounds, limits in applicability of existing magnetic-flux-pinning models are also treated as well as methods for determining critical magnetic fields.

  15. Effect of disorder on the superconducting properties of materials

    International Nuclear Information System (INIS)

    Brouers, F.; Derenne, M.

    1982-01-01

    The effect of the variation of the density states at the Fermi level on the critical superconductivity temperature TC of transition metal compounds is studied. This paper suggests using the technique of calculating the 5-fold degenerate d-band density of states from a continued fraction extension of a tight-binding Green function to study the relative importance of one dimensionality chain coupling, three dimensional interactions and the effect of disorder on the electronic and superconducting properties of complex phase and in particular A15 phases. The first results obtained for A15 phases density of states indicate that an extension of the suggested method can be of great interest to analyze the effect of disorder on superconductivity properties of complex phases

  16. Applied superconductivity

    CERN Document Server

    Newhouse, Vernon L

    1975-01-01

    Applied Superconductivity, Volume II, is part of a two-volume series on applied superconductivity. The first volume dealt with electronic applications and radiation detection, and contains a chapter on liquid helium refrigeration. The present volume discusses magnets, electromechanical applications, accelerators, and microwave and rf devices. The book opens with a chapter on high-field superconducting magnets, covering applications and magnet design. Subsequent chapters discuss superconductive machinery such as superconductive bearings and motors; rf superconducting devices; and future prospec

  17. Superconducting state mechanisms and properties

    CERN Document Server

    Kresin, Vladimir Z; Wolf, Stuart A

    2014-01-01

    'Superconducting State' provides a very detailed theoretical treatment of the key mechanisms of superconductivity, including the current state of the art (phonons, magnons, and plasmons). A very complete description is given of the electron-phonon mechanism responsible for superconductivity in the majority of superconducting systems, and the history of its development, as well as a detailed description of the key experimental techniques used to study the superconducting state and determine the mechanisms. In addition, there are chapters describing the discovery and properties of the key superconducting compounds that are of the most interest for science, and applications including a special chapter on the cuprate superconductors. It provides detailed treatments of some very novel aspects of superconductivity, including multiple bands (gaps), the "pseudogap" state, novel isotope effects beyond BCS, and induced superconductivity.

  18. the tj model and superconductivity

    African Journals Online (AJOL)

    DJFLEX

    Perhaps that in the reason why their explanations of the superconductivity have had limited scope . A proper theory and mechanism of superconductivity in the ceramic cuprates should take account of magnetism inherent in the compounds. For the (214) compound experiment have revealed strong antiferromagnetic (AF).

  19. Inelastic neutron scattering study of a nonmagnetic collapsed tetragonal phase in nonsuperconducting CaFe2As2: evidence of the impact of spin fluctuations on superconductivity in the iron-arsenide compounds.

    Science.gov (United States)

    Soh, J H; Tucker, G S; Pratt, D K; Abernathy, D L; Stone, M B; Ran, S; Bud'ko, S L; Canfield, P C; Kreyssig, A; McQueeney, R J; Goldman, A I

    2013-11-27

    The relationship between antiferromagnetic spin fluctuations and superconductivity has become a central topic of research in studies of superconductivity in the iron pnictides. We present unambiguous evidence of the absence of magnetic fluctuations in the nonsuperconducting collapsed tetragonal phase of CaFe2As2 via inelastic neutron scattering time-of-flight data, which is consistent with the view that spin fluctuations are a necessary ingredient for unconventional superconductivity in the iron pnictides. We demonstrate that the collapsed tetragonal phase of CaFe2As2 is nonmagnetic, and discuss this result in light of recent reports of high-temperature superconductivity in the collapsed tetragonal phase of closely related compounds.

  20. Academic training: Applied superconductivity

    CERN Multimedia

    2007-01-01

    LECTURE SERIES 17, 18, 19 January from 11.00 to 12.00 hrs Council Room, Bldg 503 Applied Superconductivity : Theory, superconducting Materials and applications E. PALMIERI/INFN, Padova, Italy When hearing about persistent currents recirculating for several years in a superconducting loop without any appreciable decay, one realizes that we are dealing with a phenomenon which in nature is the closest known to the perpetual motion. Zero resistivity and perfect diamagnetism in Mercury at 4.2 K, the breakthrough during 75 years of several hundreds of superconducting materials, the revolution of the "liquid Nitrogen superconductivity"; the discovery of still a binary compound becoming superconducting at 40 K and the subsequent re-exploration of the already known superconducting materials: Nature discloses drop by drop its intimate secrets and nobody can exclude that the last final surprise must still come. After an overview of phenomenology and basic theory of superconductivity, the lectures for this a...

  1. Interplay of magnetism and superconductivity in the compressed Fe-ladder compound BaFe2Se3

    Energy Technology Data Exchange (ETDEWEB)

    Ying, Jianjun; Lei, Hechang; Petrovic, Cedomir; Xiao, Yuming; Struzhkin, Viktor V. (BNL); (CIW)

    2017-06-01

    High pressure resistance, susceptibility, and Fe K β x-ray emission spectroscopy measurements were performed on Fe-ladder compound BaFe 2 Se 3 . Pressure-induced superconductivity was observed which is similar to the previously reported superconductivity in the BaFe 2 S 3 samples. The slope of local magnetic moment versus pressure shows an anomaly across the insulator-metal transition pressure in the BaFe 2 Se 3 samples. The local magnetic moment is continuously decreasing with increasing pressure, and the superconductivity appears only when the local magnetic moment value is comparable to the one in the iron-pnictide superconductors. Our results indicate that the compressed BaFe 2 C h 3 ( C h = S , Se) is a new family of iron-based superconductors. Despite the crystal structures completely different from the known iron-based superconducting materials, the magnetism in this Fe-ladder material plays a critical role in superconductivity. This behavior is similar to the other members of iron-based superconducting materials.

  2. Structural studies of type N superconductive compounds: R2-xCexCuO4±δ (R = Gd, Eu, Sm, Nd, Pr); influences of chemical treatments on physical properties

    International Nuclear Information System (INIS)

    Vigoureux, P.

    1995-06-01

    Different chemical treatments of R 2-x Ce x CuO 4±δ compounds monocrystals (gadolinium, europium, samarium, neodymium and praseodymium cuprates) modify their physical properties especially their superconductive properties. The presented chemical treatments are: the substitution of the trivalent rare earth element R by an other trivalent lanthanide, its substitution by tetravalent cerium, and heat treatment under low oxygen pressure. After these chemical treatments, structural modifications are observed by neutrons and X-rays diffraction, and allow to precise their actions: size effect of the rare earth element on the deformation of the CuO 2 planes, links between deformation and superconductivity and magnetic properties. (A.B.)

  3. Preparation process of an yttrium (or one rare earth), one alkaline earth metal, copper and oxygen superconductive compound

    International Nuclear Information System (INIS)

    Michel, C.; Pham Ai-Qooc; Raveau, B.

    1991-01-01

    The present invention describes the fabrication at atmospheric pressure of a compound based on yttrium (or a rare earth), one alkaline earth metal, copper, and oxygen so as to get a high-tc superconductor material. 2 refs

  4. Ceramic superconductor/metal composite materials employing the superconducting proximity effect

    Science.gov (United States)

    Holcomb, Matthew J.

    2002-01-01

    Superconducting composite materials having particles of superconducting material disposed in a metal matrix material with a high electron-boson coupling coefficient (.lambda.). The superconducting particles can comprise any type of superconductor including Laves phase materials, Chevrel phase materials, A15 compounds, and perovskite cuprate ceramics. The particles preferably have dimensions of about 10-500 nanometers. The particles preferably have dimensions larger than the superconducting coherence length of the superconducting material. The metal matrix material has a .lambda. greater than 0.2, preferably the .lambda. is much higher than 0.2. The metal matrix material is a good proximity superconductor due to its high .lambda.. When cooled, the superconductor particles cause the metal matrix material to become superconducting due to the proximity effect. In cases where the particles and the metal matrix material are chemically incompatible (i.e., reactive in a way that destroys superconductivity), the particles are provided with a thin protective metal coating. The coating is chemically compatible with the particles and metal matrix material. High Temperature Superconducting (HTS) cuprate ceramic particles are reactive and therefore require a coating of a noble metal resistant to oxidation (e.g., silver, gold). The proximity effect extends through the metal coating. With certain superconductors, non-noble metals can be used for the coating.

  5. Superconductivity fundamentals and applications

    CERN Document Server

    Buckel, Werner

    2004-01-01

    This is the second English edition of what has become one of the definitive works on superconductivity in German -- currently in its sixth edition. Comprehensive and easy to understand, this introductory text is written especially with the non-specialist in mind. The authors, both long-term experts in this field, present the fundamental considerations without the need for extensive mathematics, describing the various phenomena connected with the superconducting state, with liberal insertion of experimental facts and examples for modern applications. While all fields of superconducting phenomena are dealt with in detail, this new edition pays particular attention to the groundbreaking discovery of magnesium diboride and the current developments in this field. In addition, a new chapter provides an overview of the elements, alloys and compounds where superconductivity has been observed in experiments, together with their major characteristics. The chapter on technical applications has been considerably expanded...

  6. Low-temperature field evaporation of Nb3Sn compound

    International Nuclear Information System (INIS)

    Ksenofontov, V.A.; Kul'ko, V.B.; Kutsenko, P.A.

    1986-01-01

    Investigation results on field evaporation of superconducting Nb 3 Sn compound wth A15 lattice are presented. Compound evaporation is shown to proceed in two stages. Evaporation field and ionic composition of evaporating material are determined. It is found out that in strong electric fields compound surface represents niobium skeleton, wich does not form regular image. Comparison of ion-microscopic and calculated images formed by low-temperature field evaporation indicates to possibility of sample surface reconstruction after preferable tin evaporation

  7. Superconductivity at 43 K in an iron-based layered compound LaO(1-x)F(x)FeAs.

    Science.gov (United States)

    Takahashi, Hiroki; Igawa, Kazumi; Arii, Kazunobu; Kamihara, Yoichi; Hirano, Masahiro; Hosono, Hideo

    2008-05-15

    The iron- and nickel-based layered compounds LaOFeP (refs 1, 2) and LaONiP (ref. 3) have recently been reported to exhibit low-temperature superconducting phases with transition temperatures T(c) of 3 and 5 K, respectively. Furthermore, a large increase in the midpoint T(c) of up to approximately 26 K has been realized in the isocrystalline compound LaOFeAs on doping of fluoride ions at the O2- sites (LaO(1-x)F(x)FeAs). Experimental observations and theoretical studies suggest that these transitions are related to a magnetic instability, as is the case for most superconductors based on transition metals. In the copper-based high-temperature superconductors, as well as in LaOFeAs, an increase in T(c) is often observed as a result of carrier doping in the two-dimensional electronic structure through ion substitution in the surrounding insulating layers, suggesting that the application of external pressure should further increase T(c) by enhancing charge transfer between the insulating and conducting layers. The effects of pressure on these iron oxypnictide superconductors may be more prominent than those in the copper-based systems, because the As ion has a greater electronic polarizability, owing to the covalency of the Fe-As chemical bond, and, thus, is more compressible than the divalent O2- ion. Here we report that increasing the pressure causes a steep increase in the onset T(c) of F-doped LaOFeAs, to a maximum of approximately 43 K at approximately 4 GPa. With the exception of the copper-based high-T(c) superconductors, this is the highest T(c) reported to date. The present result, together with the great freedom available in selecting the constituents of isocrystalline materials with the general formula LnOTMPn (Ln, Y or rare-earth metal; TM, transition metal; Pn, group-V, 'pnicogen', element), indicates that the layered iron oxypnictides are promising as a new material platform for further exploration of high-temperature superconductivity.

  8. Superconductivity up to 114 K in the Bi-Al-Ca-Sr-Cu-O compound system without rare-earth elements

    Science.gov (United States)

    Chu, C. W.; Bechtold, J.; Gao, L.; Hor, P. H.; Huang, Z. J.

    1988-01-01

    Stable superconductivity up to 114 K has been reproducibly detected in Bi-Al-Ca-Sr-Cu-O multiphase systems without any rare-earth elements. Pressure has only a slight positive effect on T(c). These observations provide an extra material base for the study of the mechanism of high-temperature superconductivity and also the prospect of reduced material cost for future applications of superconductivity.

  9. Preparation, crystal structure and physical properties of the superconducting cage compound Ba{sub 3}Ge{sub 16}Ir{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Duong Nguyen, Hong; Prots, Yurii; Schnelle, Walter; Boehme, Bodo; Baitinger, Michael; Grin, Yuri [Max-Planck-Institut fuer Chemische Physik fester Stoffe, Noethnitzer Str. 40, 01187 Dresden (Germany); Paschen, Silke [Institut fuer Festkoerperphysik, Technische Universitaet Wien, Wiedner Hauptstrasse 8-10, 1040 Wien (Austria)

    2014-04-15

    The cage compound Ba{sub 3}Ge{sub 16}Ir{sub 4} crystallizes with the Ba{sub 3}Ge{sub 16}Rh{sub 4} type of crystal structure, which represents a hierarchical derivative of the BaAl{sub 4} type. The crystal structure [Pearson symbol tI46, space group I4/mmm; a = 6.5312(2) Aa, c = 22.2845(6) Aa] was refined from single-crystal X-ray diffraction data. The phase was obtained after 10 d at 910 C with small impurities of clathrate-I, BaGe{sub 7}Ir{sub 2} and α-Ge remaining at the grain boundaries. Ba{sub 3}Ge{sub 16}Ir{sub 4} is a Pauli-paramagnetic metal, which becomes superconducting below T{sub c} = 5.1 K. Electronic structure and analysis of the chemical bonding were performed based on density functional theory calculations. The physical properties are discussed in comparison to the isotypic phase Ba{sub 3}Ge{sub 16}Rh{sub 4}. (Copyright copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  10. Superconductivity and magnetism in the oxypnictides: high field ESR and {mu}SR studies of (La,Gd)FeAsO{sub 1-x}F{sub x} compounds

    Energy Technology Data Exchange (ETDEWEB)

    Muranyi, Ferenc [Physics Institute, University of Zuerich (Switzerland); IFW Dresden (Germany); Alfonsov, Alexey; Kataev, Vladislav; Koehler, Anke; Werner, Jochen; Behr, Guenter; Leps, Norman; Klingeler, Ruediger; Kondrat, Agnieszka; Hess, Christian; Buechner, Bernd [IFW Dresden (Germany); Khasanov, Rustem; Luetkens, Hubertus [Paul Scherrer Institut, Villigen PSI (Switzerland); Klaus, Hans-Henning [IFP, TU Dresden (Germany)

    2009-07-01

    The discovery of a new class of superconducting materials, ReFeAsO{sub 1-x}F{sub x}, stirred up the scientific community. Here we report the Gd{sup 3+} high field ESR study of differently doped (La,Gd)FeAsO{sub 1-x}F{sub x} compounds. In lightly Gd-doped LaFeAsO samples the SDW transition yields line-broadening at the transition temperature, the SDW transition is then suppressed upon F-doping. In the dense compound, GdFeAsO, with SDW transition around 140 K, the Gd-ESR was also studied. With 15% F-doping superconductivity appears at {proportional_to} 21 K. The SDW and SC transitions are clearly seen in ESR and in {mu} SR as well. Surprisingly the reminiscence of the SDW transition of the undoped material (GdFeAsO) was identified in the doped (15% F) compound at lower temperature ({proportional_to} 80 K). This indicates the importance of the the interplay between superconductivity and magnetism in oxypnictides.

  11. Superconductivity revisited

    CERN Document Server

    Dougherty, Ralph

    2013-01-01

    While the macroscopic phenomenon of superconductivity is well known and in practical use worldwide in many industries, including MRIs in medical diagnostics, the current theoretical paradigm for superconductivity (BCS theory) suffers from a number of limitations, not the least of which is an adequate explanation of high temperature superconductivity. This book reviews the current theory and its limitations and suggests new ideas and approaches in addressing these issues. The central objective of the book is to develop a new, coherent, understandable theory of superconductivity directly based on molecular quantum mechanics.

  12. Materials for superconducting cavities

    International Nuclear Information System (INIS)

    Bonin, B.

    1996-01-01

    The ideal material for superconducting cavities should exhibit a high critical temperature, a high critical field, and, above all, a low surface resistance. Unfortunately, these requirements can be conflicting and a compromise has to be found. To date, most superconducting cavities for accelerators are made of niobium. The reasons for this choice are discussed. Thin films of other materials such as NbN, Nb 3 Sn, or even YBCO compounds can also be envisaged and are presently investigated in various laboratories. It is shown that their success will depend critically on the crystalline perfection of these films. (author)

  13. Heat capacities and phase analysis of the superconductive compounds Mosub(6+y0) Se8 and Gdsub(x0) Mosub(6+y0) Se8

    International Nuclear Information System (INIS)

    Nerz, K.P.

    1979-02-01

    High precision heat capacity measurements were performed on a high quality sample of Mo 6 Se 8 . The values obtained for the Sommerfeld-constant γ, density of states N(Esub(F)) and entropy S 2 (Tsub(c)) of the electronic system are a factor 1.5 to 2 larger than have been published earlier by other groups. The differences are attributed to the lower concentration of impurity phases in our sample. Our sample of Mo 6 Se 8 shows a discontinuity in the electronic heat capacity at Tsub(c) with a relative height (Csub(es)-Csub(en))/Csub(en) which is a factor 1.6 larger compared to an ideal BCS-superconductor. The energy gap in the excitation spectrum of the superconductor Mo 6 Se 8 is a factor 1.4 wider than for an ideal BCS-superconductor in the observed temperature regime. Our data for the electronic heat capacity of the superconducting phase Mo 6 Se 8 are in good agreement with the calculated values corresponding to the 'strong coupling'-model of Padamsee et al. For the characteristic quantity of the electron-phonon interaction, lambda, a value of 0.8 was calculated. All these results support the conclusions that Mo 6 Se 8 behaves like a superconductor with a strong electron-phonon interaction. In addition heat capacity measurements have been made for samples of the ternary Chevrel-phase compounds 'Gdsub(x 0 )Mosub(6+y 0 )Se 8 ' which were prepared by a variety of methods. A quantitative analysis of impurity phases has been made from the heat capacity data. (orig.) [de

  14. Superconductors for superconducting magnets

    Science.gov (United States)

    Larbalestier, David

    2011-03-01

    Even in 1913 Kamerlingh Onnes envisioned the use of superconductors to create powerful magnetic fields well beyond the capability provided by cooling normal metals with liquid helium. Only some ``bad places'' in his Hg and Pb wires seemed to impede his first attempts at this dream, one that he imagined would be resolved in a few weeks of effort. In fact, of course, resolution required another 50 years and development of both a true understanding of the difference between type I and type II superconductors and the discovery of compounds such as Nb 3 Sn that could remain superconducting to fields as high as 30 T. And then indeed, starting in the 1960s, Onnes's dreams were comfortably surpassed. In the last 45 years virtually all superconducting magnets have been made from just two Nb-base materials, Nb-Ti and Nb 3 Sn. Now it seems that a new generation of magnets based on cuprate high temperature superconductors with fields well above 30 T are possible using Bi-Sr-Ca-Cu-O and the RE-Ba-Cu-O compounds. We hope that a first demonstration of this possibility will be an all-superconducting 32 T magnet with RE-Ba-Cu-O insert that we are building for NHMFL users. The magnet application potential of this new generation of superconducting conductors will be discussed.

  15. Organic superconductivity

    International Nuclear Information System (INIS)

    Jerome, D.

    1980-01-01

    We present the experimental evidences for the existence of a superconducting state in the Quasi One Dimensional organic conductor (TMTSF) 2 PF 6 . Superconductivity occuring at 1 K under 12 kbar is characterized by a zero resistance diamagnetic state. The anistropy of the upper critical field of this type II superconductor is consistent with the band structure anistropy. We present evidences for the existence of large superconducting precursor effects giving rise to a dominant paraconductive contribution below 40 K. We also discuss the anomalously large pressure dependence of T sb(s), which drops to 0.19 K under 24 kbar in terms of the current theories. (author)

  16. Superconducting linac

    International Nuclear Information System (INIS)

    Bollinger, L.M.; Shepard, K.W.; Wangler, T.P.

    1978-01-01

    This project has two goals: to design, build, and test a small superconducting linac to serve as an energy booster for heavy ions from an FN tandem electrostatic accelerator, and to investigate various aspects of superconducting rf technology. The main design features of the booster are described, a status report on various components (resonators, rf control system, linac control system, cryostats, buncher) is given, and plans for the near future are outlined. Investigations of superconducting-linac technology concern studies on materials and fabrication techniques, resonator diagnostic techniques, rf-phase control, beam dynamics computer programs, asymmetry in accelerating field, and surface-treatment techniques. The overall layout of the to-be-proposed ATLAS, the Argonne Tandem-Linac Accelerator System, is shown; the ATLAS would use superconducting technology to produce beams of 5 to 25 MeV/A. 6 figures

  17. Superconducting materials

    International Nuclear Information System (INIS)

    Kormann, R.; Loiseau, R.; Marcilhac, B.

    1989-01-01

    The invention concerns superconducting ceramics containing essentially barium, calcium and copper fluorinated oxides with close offset and onset temperatures around 97 K and 100 K and containing neither Y nor rare earth [fr

  18. Superconductivity: Phenomenology

    International Nuclear Information System (INIS)

    Falicov, L.M.

    1988-08-01

    This document discusses first the following topics: (a) The superconducting transition temperature; (b) Zero resistivity; (c) The Meissner effect; (d) The isotope effect; (e) Microwave and optical properties; and (f) The superconducting energy gap. Part II of this document investigates the Ginzburg-Landau equations by discussing: (a) The coherence length; (b) The penetration depth; (c) Flux quantization; (d) Magnetic-field dependence of the energy gap; (e) Quantum interference phenomena; and (f) The Josephson effect

  19. ASC 84: applied superconductivity conference. Final program and abstracts

    Energy Technology Data Exchange (ETDEWEB)

    1984-01-01

    Abstracts are given of presentations covering: superconducting device fabrication; applications of rf superconductivity; conductor stability and losses; detectors and signal processing; fusion magnets; A15 and Nb-Ti conductors; stability, losses, and various conductors; SQUID applications; new applications of superconductivity; advanced conductor materials; high energy physics applications of superconductivity; electronic materials and characterization; general superconducting electronics; ac machinery and new applications; digital devices; fusion and other large scale applications; in-situ and powder process conductors; ac applications; synthesis, properties, and characterization of conductors; superconducting microelectronics. (LEW)

  20. ASC 84: applied superconductivity conference. Final program and abstracts

    International Nuclear Information System (INIS)

    1984-01-01

    Abstracts are given of presentations covering: superconducting device fabrication; applications of rf superconductivity; conductor stability and losses; detectors and signal processing; fusion magnets; A15 and Nb-Ti conductors; stability, losses, and various conductors; SQUID applications; new applications of superconductivity; advanced conductor materials; high energy physics applications of superconductivity; electronic materials and characterization; general superconducting electronics; ac machinery and new applications; digital devices; fusion and other large scale applications; in-situ and powder process conductors; ac applications; synthesis, properties, and characterization of conductors; superconducting microelectronics

  1. Alternative superconducting systems

    International Nuclear Information System (INIS)

    1992-01-01

    In the context of the experiment on 'Development of high temperature superconducting system components' supported by the German Ministry of Research and Technology, investigations were carried out by the Working Party of Prof. von Schnering at the Max Planck Institute for Solids Research, the aim of which is to find characteristic structural features of superconducting substances. Alternative systems are to be looked for with the aid of correlation of superconducting properties with simple electronic and chemical structure models, where very powerful 3D computer graphics are used to visualize them. The theoretical and information technology part of the work was supplemented by experiments. Superconducting phases and related compounds were represented and their structures and physical properties were determined. According to the tasks described above, the report is divided into three sections. Starting with the description of a program system for three-dimensional representation of structures and properties of periodic systems, in the second section a process for calculating node surfaces is explained and the importance of curvature in chemical structures is pointed out. The results of the experiments are collected in the third part. (orig.) [de

  2. Metastable superconducting alloys

    International Nuclear Information System (INIS)

    Johnson, W.L.

    1978-07-01

    The study of metastable metals and alloys has become one of the principal activities of specialists working in the field of superconducting materials. Metastable crystalline superconductors such as the A15-type materials have been given much attention. Non-crystalline superconductors were first studied over twenty years ago by Buckel and Hilsch using the technique of thin film evaporation on a cryogenic substrate. More recently, melt-quenching, sputtering, and ion implantation techniques have been employed to produce a variety of amorphous superconductors. The present article presents a brief review of experimental results and a survey of current work on these materials. The systematics of superconductivity in non-crystalline metals and alloys are described along with an analysis of the microscopic parameters which underlie the observed trends. The unique properties of these superconductors which arise from the high degree of structural disorder in the amorphous state are emphasized

  3. Superconductivity in metal-coated graphene

    Energy Technology Data Exchange (ETDEWEB)

    Calandra, Matteo; Mauri, Francesco [IMPMC, Universite Paris 6, CNRS, 4 Place Jussieu, 75005 Paris (France); Profeta, Gianni [SPIN-CNR - Dipartimento di Fisica Universita degli Studi di L' Aquila, 67100 L' Aquila (Italy)

    2012-12-15

    In this work we explore, by first-principles density functional theory (DFT) calculations, the possibility of inducing electron-phonon mediated superconductivity in a graphene sheet by doping its surface with alkaline metal adatoms. We demonstrate that, contrary to what could be naively believed, simple exfoliation to one layer of superconducting graphite intercalated compounds (GICs) does not necessarily lead to superconducting graphene, as it is the case in CaC{sub 6}. On the contrary, it is meaningful to look for superconductivity in monolayers obtained by exfoliating non-superconducting GICs. In particular, we demonstrate that Li coating and double-coating of graphene leads to superconductivity in graphene with T{sub c} that could be as large as 18 K. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  4. Superconducting rotating electronic machine

    International Nuclear Information System (INIS)

    Cheon, Hui Yeong

    1989-04-01

    This book is divided into ten chapters, which handles summary of superconducting electronic machine, aspect of using of superconductor, superconducting direct current : Homopolar D. C. Machines, Drum machines, segmented slip-ring principle and carbon fibre brushes, superconducting alternating current turbine generator, design of superconducting alternating current machine, performance of superconducting alternating current machine, superconducting turbo generator by new rotor design, basic design of superconducting current generator, generator and power model, design of rotor and information of material property.

  5. Coexistence of magnetism and superconductivity in the iron-based compound Cs0.8(FeSe0.98)2.

    Science.gov (United States)

    Shermadini, Z; Krzton-Maziopa, A; Bendele, M; Khasanov, R; Luetkens, H; Conder, K; Pomjakushina, E; Weyeneth, S; Pomjakushin, V; Bossen, O; Amato, A

    2011-03-18

    We report on muon-spin rotation and relaxation (μSR), electrical resistivity, magnetization and differential scanning calorimetry measurements performed on a high-quality single crystal of Cs(0.8)(FeSe(0.98))(2). Whereas our transport and magnetization data confirm the bulk character of the superconducting state below T(c)=29.6(2)  K, the μSR data indicate that the system is magnetic below T(N)=478.5(3)  K, where a first-order transition occurs. The first-order character of the magnetic transition is confirmed by differential scanning calorimetry data. Taken all together, these data indicate in Cs(0.8)(FeSe(0.98))(2) a microscopic coexistence between the superconducting phase and a strong magnetic phase. The observed T(N) is the highest reported to date for a magnetic superconductor.

  6. Superconducting transistor

    International Nuclear Information System (INIS)

    Gray, K.E.

    1978-01-01

    A three film superconducting tunneling device, analogous to a semiconductor transistor, is presented, including a theoretical description and experimental results showing a current gain of four. Much larger current gains are shown to be feasible. Such a development is particularly interesting because of its novelty and the striking analogies with the semiconductor junction transistor

  7. Superconducting materials

    International Nuclear Information System (INIS)

    Ruvalds, J.

    1990-01-01

    This report discusses the following topics: Fermi liquid nesting in high temperature superconductors; optical properties of high temperature superconductors; Hall effect in superconducting La 2-x Sr x CuO 4 ; source of high transition temperatures; and prospects for new superconductors

  8. Superconducting magnets

    International Nuclear Information System (INIS)

    1994-08-01

    This report discusses the following topics on superconducting magnets: D19B and -C: The next steps for a record-setting magnet; D20: The push beyond 10 T: Beyond D20: Speculations on the 16-T regime; other advanced magnets for accelerators; spinoff applications; APC materials development; cable and cabling-machine development; and high-T c superconductor at low temperature

  9. Bipolar superconductivity

    International Nuclear Information System (INIS)

    Pankratov, S.G.

    1987-01-01

    A model of bipolaron superconductivity suggested by Soviet scientist Alexandrov A.S. and French scientist Ranninger is presentes in a popular way. It is noted that the bipolaron theory gives a good explanation of certain properties of new superconductors, high critical temperature, in particular

  10. Moessbauer study of superconducting NdFeAsO{sub 0.88}F{sub 0.12} and its parent compound NdFeAsO

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez, D R [Instituto de Fisica, Universidade Federal Fluminense, Avenida Milton Tavares de Souza, s/n-Campus da Praia Vermelha, 24210-346 Niteroi, RJ (Brazil); Alzamora, M; Munevar, J; Baggio-Saitovitch, E [Centro Brasileiro de Pesquisas Fisicas, Rua Xavier Sigaud 150, Urca 22290-180, Rio de Janeiro, RJ (Brazil); Wang, N L; Cheng, G F, E-mail: dalber@if.uff.b [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100080 (China)

    2009-11-11

    {sup 57}Fe Moessbauer spectroscopy has been used to investigate the magnetic order of non-superconducting NdFeAsO (T{sub N} = 140 K) and superconducting NdFeAsO{sub 0.88}F{sub 0.12} (T{sub c} = 45 K). A magnetic hyperfine field B{sub hf} was observed at the {sup 57}Fe nucleus below T{sub N}approx140 K for NdFeAsO. Below approx2 K an increase of B{sub hf} relative to the saturation value was attributed to the transferred B{sub hf} at the Fe site resulting from the collinear antiferromagnetic (AF) spin structure of the Nd moments. The analysis of the spectra is consistent with a commensurate AF order of Fe spins. No B{sub hf} is observed in superconducting NdFeAsO{sub 0.88}F{sub 0.12} down to 1.5 K.

  11. Magnetic and superconductive property study of the compounds: HoMo6S8, EuMo6S8 and Ce Mo6S8

    International Nuclear Information System (INIS)

    Dinia, M.A.

    1987-07-01

    Magnetic measurements and neutron spectroscopy measurements allowed to conclude that HoMo 6 S 8 was an Ising system. Neutron diffraction experiments and electric conductivity measurements simultaneously on a HoMo 6 S 8 monocrystal allowed to set that at null field superconductivity exists not only with the modulated magnetic structure but also with an antiphase magnetic structure (in a narrow temperature range). Superconductivity disparition at low temperature is then not related to the magnetic transition but to the development of magnetic moments of Ho 3+ ions. Superconducting phase got at low temperature by heating a monodomain ferromagnetic crystal is associated to a reduction of the ordered moment of Ho 3+ ions, because of an important demagnetizing field. At last, magnetic order evolution study in relation to the magnetic field allowed to precise the phase diagram of HoMo 6 S 8 . A crystal structure study of EuMo 6 S 8 in the high temperature rhomboedric phase and the low temperature triclinic phase were realized by neutron diffraction. Magnetic order in EuMo 6 S 8 below T N = 0.3K was determined [fr

  12. Direct observation of the growth of voids in multifilamentary superconducting materials via hot stage scanning electron microscopy

    International Nuclear Information System (INIS)

    Wang, J.L.F.; Holthuis, J.T.; Pickus, M.R.; Lindberg, R.W.

    1978-11-01

    The need for large high field magnetic devices has focused attention on multifilamentary superconductors based on A15 compounds such as Nb 3 Sn. The commercial bronze process for fabricating multifilamentary superconducting Nb 3 Sn wires was developed. A major problem is strain sensitivity when long reaction times are employed. An improved hot stage for the scanning electron microscope was constructed to study the formation of the A15 phase by solid state diffusion. The nucleation and growth of voids near the interface of the A15 phase (Nb 3 Sn) and matrix were observed, monitored, and recorded on video tape. Successive layers of material heated in the hot stage were subsequently removed and the new surfaces were re-examined, using SEM-EDX and optical microscopy, to confirm the fact that the observed porosity was indeed a bulk rather than a surface phenomenon. These voids are considered to be a primary cause for degrading the mechanical, thermal and superconducting properties

  13. A15 multifilamentary superconductors by the infiltration process

    International Nuclear Information System (INIS)

    Pickus, M.R.; Holthuis, J.T.; Rosen, M.

    1980-05-01

    The inherent brittleness of the A15 compounds, and the requirement for a filamentary morphology, led to a heavy reliance on a powder approach for the preparation of superconducting tapes and wires. The quench-age technique, a non-powder process, was employed for the niobium-aluminum system, following the special features of the equilibrium phase diagram. The powder approach proved particularly effective for binaries, such as Nb-Sn, and for the ternaries Nb(Al,Ge) and Nb(Al,Si). Two variations of the powder process were assessed. One involved the use of precompounded powder of the desired stoichiometry but required simultaneous application of heat and pressure. The second variation was the infiltration process. This process involves the preparation of a ductile niobium matrix containing a controlled network of interconnected pores which are subsequently infiltrated with liquid metals (Sn) or low melting-point eutectics (e.g., Al-Ge, Al-Si). The composite is then subjected to a thermomechanical treatment to form a multiply connected array of A15 filaments in a niobium matrix. Multifilamentary conductors, based on Nb 3 Sn, Nb 3 Al, Nb 3 (Al,Ge) and Nb 3 (Al,Si), were readily obtained. Nb 3 Sn conductors made by the infiltration process exhibit a critical temperature (Tc) of 18.1 K and a critical current carrying capacity (I/sub c/) of 8 x 10 4 amp.cm -2 at 12 Tesla

  14. Color superconductivity

    Energy Technology Data Exchange (ETDEWEB)

    Wilczek, F. [Institute for Advanced Study, Princeton, NJ (United States)

    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.

  15. Modern aspects of superconductivity theory of superconductivity

    CERN Document Server

    Kruchinin, Sergei; Aono, Shigeyuki

    2011-01-01

    Superconductivity remains one of the most interesting research areas in physics and stood as a major scientific mystery for a large part of this century. This book, written for graduate students and researchers in the field of superconductivity, discusses important aspects of the experiment and theory surrounding superconductivity. New experimental investigations of magnetic and thermodynamic superconducting properties of mesoscopic samples are explored with the help of recent developments in nanotechnologies and measurement techniques, and the results are predicted based upon theoretical mode

  16. Superconducting plasmas

    International Nuclear Information System (INIS)

    Ohnuma, Toshiro; Ohno, J.

    1994-01-01

    Superconducting (SC) plasmas are proposed and investigated. The SC plasmas are not yet familiar and have not yet been studied. However, the existence and the importance of SC plasmas are stressed in this report. The existence of SC plasmas are found as follows. There is a fundamental property of Meissner effect in superconductors, which shows a repulsive effect of magnetic fields. Even in that case, in a microscopic view, there is a region of magnetic penetration. The penetration length λ is well-known as London's penetration depth, which is expressed as δ = (m s /μ 0 n s q s 2 ) 1/2 where m s , n s , q s and μ o show the mass, the density, the charge of SC electron and the permeability in free space, respectively. Because this expression is very simple, no one had tried it into more simple and meaningful form. Recently, one of the authors (T.O.) has found that the length can be expressed into more simple and understandable fundamental form as λ = c/ω ps where c = (ε 0 μ 0 ) -1/2 and ω ps = (n s q s 2 /m s ε 0 ) 1/2 are the light velocity and the superconducting plasma frequency. From this simple expression, the penetration depth of the magnetic field to SC is found as a SC plasma skin depth, that is, the fundamental property of SC can be expressed by the SC plasmas. This discovery indicates an importance of the studies of superconducting plasmas. From these points, several properties (propagating modes et al) of SC plasmas, which consist of SC electrons, normal electrons and lattice ions, are investigated in this report. Observations of SC plasma frequency is also reported with a use of Terahertz electromagnet-optical waves

  17. 100 years of superconductivity

    CERN Document Server

    Rogalla, Horst

    2011-01-01

    Even a hundred years after its discovery, superconductivity continues to bring us new surprises, from superconducting magnets used in MRI to quantum detectors in electronics. 100 Years of Superconductivity presents a comprehensive collection of topics on nearly all the subdisciplines of superconductivity. Tracing the historical developments in superconductivity, the book includes contributions from many pioneers who are responsible for important steps forward in the field.The text first discusses interesting stories of the discovery and gradual progress of theory and experimentation. Emphasizi

  18. Superconducting accelerator technology

    International Nuclear Information System (INIS)

    Grunder, H.A.; Hartline, B.K.

    1986-01-01

    Modern and future accelerators for high energy and nuclear physics rely increasingly on superconducting components to achieve the required magnetic fields and accelerating fields. This paper presents a practical overview of the phenomenon of superconductivity, and describes the design issues and solutions associated with superconducting magnets and superconducting rf acceleration structures. Further development and application of superconducting components promises increased accelerator performance at reduced electric power cost

  19. Valence skipping driven superconductivity and charge Kondo effect

    International Nuclear Information System (INIS)

    Yanagisawa, Takashi; Hase, Izumi

    2013-01-01

    Highlights: •Valence skipping in metallic compounds can give rise to an unconventional superconductivity. •Several elements in the periodic table show valence skipping (or valence missing), for example, Bi forms the compounds in valence states +3 and +5. •The doping of valence skipping elements will induce superconductivity and this will lead to a possibility of high temperature superconductivity. •We consider the Wolf model with negative-U impurities, and show a phase diagram including superconducting phase. •There is a high temperature region near the boundary. -- Abstract: Valence skipping in metallic compounds can give rise to an unconventional superconductivity. Several elements in the periodic table show valence skipping (or valence missing), for example, Bi forms the compounds in valence states +3 and +5. The doping of valence skipping elements will induce superconductivity and this will lead to a possibility of high temperature superconductivity. We consider the Wolf model with negative-U impurities, and show a phase diagram including superconducting phase. The superconducting state is changed into a metallic state with a local singlet as the attractive interaction |U| increases. There is a high temperature region near the boundary

  20. Phonon-mediated superconductivity in graphene by lithium deposition

    Science.gov (United States)

    Profeta, Gianni; Calandra, Matteo; Mauri, Francesco

    2012-02-01

    Graphene is the physical realization of many fundamental concepts and phenomena in solid-state physics. However, in the list of graphene's many remarkable properties, superconductivity is notably absent. If it were possible to find a way to induce superconductivity, it could improve the performance and enable more efficient integration of a variety of promising device concepts including nanoscale superconducting quantum interference devices, single-electron superconductor-quantum dot devices, nanometre-scale superconducting transistors and cryogenic solid-state coolers. To this end, we explore the possibility of inducing superconductivity in a graphene sheet by doping its surface with alkaline metal adatoms, in a manner analogous to which superconductivity is induced in graphite intercalated compounds (GICs). As for GICs, we find that the electrical characteristics of graphene are sensitive to the species of adatom used. However, contrary to what happens in GICs, Li-covered graphene is superconducting at a much higher temperature with respect to Ca-covered graphene.

  1. Coexistence of antiferromagnetism and superconductivity in heavy fermion cerium compound Ce.sub.3./sub.PdIn.sub.11./sub

    Czech Academy of Sciences Publication Activity Database

    Kratochvílová, M.; Prokleška, J.; Uhlířová, K.; Tkáč, V.; Dušek, Michal; Sechovský, V.; Custers, J.

    2015-01-01

    Roč. 5, Oct (2015), s. 15904 ISSN 2045-2322 R&D Projects: GA ČR(CZ) GAP204/11/0809 Institutional support: RVO:68378271 Keywords : crystal structure * magnetic transition * heavy fermion compounds * antiferromagnetism Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 5.228, year: 2015

  2. Technetium compounds and their field of application

    International Nuclear Information System (INIS)

    Zaitseva, L.L.; Velichko, A.V.; Vinogradov, I.V.

    1988-02-01

    This chapter reviews the different applications of technetium and technetium compounds in catalysis, corrosion inhibition, superconductivity of technetium alloys, diagnostic techniques, radioisotope generators and radiopharmaceuticals. 649 refs [fr

  3. Change in properties of superconducting magnet materials by fusion neutron irradiation

    International Nuclear Information System (INIS)

    Nishimura, Arata; Nishijima, Shigehiro; Takeuchi, Takao; Nishitani, Takeo

    2007-01-01

    A fusion reactor will generate a lot of high energy neutron and much energy will be taken out of the neutrons by a blanket system. Since some neutrons will stream out of a plasma vacuum vessel through neutral beam injection ports and penetrate a blanket system, a superconducting magnet system, which provides high magnetic field to confirm high energy particles, will be irradiated by a certain amount of neutrons. By developing the new NBI system or by reducing the penetration, the neutron fluence to the superconducting magnet will be able to be reduced. However, it is not easy to achieve the lower streaming and penetration at the present. Therefore, investigations on irradiation behavior of superconducting magnet materials are desired and some novel researches have been performed from 1970s. In general, the critical current of the superconducting wire increases under fast neutron environment comparing with that of the non-irradiated wire, and then decreased to almost zero as an increase of neutron fluence. On the other hand, the critical temperature of the wire starts to get down around 10 22 n/m 2 of neutron fluence and the temperature margin will be decreased during the operation by the neutron irradiation. In this paper, some aspects of irradiated materials will be overviewed and general tendency will be discussed focussing on knock-on effect of fast neutron and long range ordering of A15 compounds

  4. Some regularities in the occurrence of superconductivity

    International Nuclear Information System (INIS)

    Chapnik, I.M.

    1984-01-01

    The superconducting transition temperatures T/sub c/ of the non-transition elements (NTE) of the first long period of the Periodic Table are compared with those of analogous compounds having NTE components from the second period. In contrast to relations for transition metals (TM) the NTE compounds show a higher T/sub c/ if the NTE component belongs to the first long period. The intermetallic compounds, crystal lattices, and T/sub c/ are listed and discussed

  5. Study of reticular defects in V3Si (A15 structure)

    International Nuclear Information System (INIS)

    Ben Lamine, Abdelmottaleb

    1980-01-01

    The A15 crystal structure is that of superconductive compounds with high critical temperature. This research thesis aims at studying its possible reticular defects. In a first part, the author presents this structure and more particularly its crystallographic properties, reports the indexing of electronic diffraction diagrams (point diagrams and line diagrams of Kikuchi) in the case of V 3 Si. Then, after having described the sample preparation technique, the author reports the study of reticular defects by high voltage electronic microscopy on a raw V 3 Si crystal. The existence of a specific defect is highlighted and the crystallographic study of this defect is reported. It has been performed by means of computer-based simulation of contrast (TWODIS software). Results are then discussed

  6. WORKSHOPS: Radiofrequency superconductivity

    International Nuclear Information System (INIS)

    Anon.

    1992-01-01

    In the continual push towards higher energy particle beams, superconducting radiofrequency techniques now play a vital role, highlighted in the fifth workshop on radiofrequency superconductivity, held at DESY from 19 - 24 August 1991

  7. Simple Superconducting "Permanent" Electromagnet

    Science.gov (United States)

    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.

  8. Superconductivity in Medicine

    Science.gov (United States)

    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.

  9. Superconductivity in transition metals.

    Science.gov (United States)

    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. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

  10. Superconductivity: Is there a problem in transuranics?

    International Nuclear Information System (INIS)

    Colineau, Eric; Griveau, Jean-Christophe; Eloirdi, Rachel; Hen, Amir; Caciuffo, Roberto

    2014-01-01

    Superconductivity was first reported in 1942 for uranium metal (¡-U) and in 1958 for U compounds: UCo, U6Mn, U6Fe, and U6Co, with critical temperatures Tc, of 1.7, 2.3, 3.9, and 2.3K, respectively. A new class of U superconductors emerged in the early 1980’s with the discovery of U heavy fermion superconductors : UBe13 (Tc = 0.85K), UPt3 (Tc = 0.53K), URu2Si2 (Tc = 1.5K) , UPd2Al3 (Tc = 1.9K) … Furthermore, in most of these systems, the superconducting phases coexist with antiferromagnetic (AF) correlations which have characteristic temperatures, usually the Néel temperature TN, that are typically one order of magnitude greater than the corresponding superconducting critical temperatures Tc. Superconductivity was even shown to co-exist with ferromagnetism in e.g. UGe2 (Tc ï» 0.8K, TC ï» 30K at p ï» 1.2GPa) and URhGe (Tc = 0.25K, TC = 9.5K). Heavy fermion superconductors still remain a major challenge for condensed matter physics. The existence of heavy fermion superconductivity and its coexistence or proximity with magnetic order suggests that the conventional mechanism of phonon-mediated superconductivity is inappropriate and that alternative mechanisms, like spin fluctuations, should be considered for Cooper pairing

  11. Controlling superconductivity by tunable quantum critical points.

    Science.gov (United States)

    Seo, S; Park, E; Bauer, E D; Ronning, F; Kim, J N; Shim, J-H; Thompson, J D; Park, Tuson

    2015-03-04

    The heavy fermion compound CeRhIn5 is a rare example where a quantum critical point, hidden by a dome of superconductivity, has been explicitly revealed and found to have a local nature. The lack of additional examples of local types of quantum critical points associated with superconductivity, however, has made it difficult to unravel the role of quantum fluctuations in forming Cooper pairs. Here, we show the precise control of superconductivity by tunable quantum critical points in CeRhIn5. Slight tin-substitution for indium in CeRhIn5 shifts its antiferromagnetic quantum critical point from 2.3 GPa to 1.3 GPa and induces a residual impurity scattering 300 times larger than that of pure CeRhIn5, which should be sufficient to preclude superconductivity. Nevertheless, superconductivity occurs at the quantum critical point of the tin-doped metal. These results underline that fluctuations from the antiferromagnetic quantum criticality promote unconventional superconductivity in CeRhIn5.

  12. Superconductivity Bordering Rashba Type Topological Transition

    Energy Technology Data Exchange (ETDEWEB)

    Jin, M. L.; Sun, F.; Xing, L. Y.; Zhang, S. J.; Feng, S. M.; Kong, P. P.; Li, W. M.; Wang, X. C.; Zhu, J. L.; Long, Y. W.; Bai, H. Y.; Gu, C. Z.; Yu, R. C.; Yang, W. G.; Shen, G. Y.; Zhao, Y. S.; Mao, H. K.; Jin, C. Q.

    2017-01-04

    Strong spin orbital interaction (SOI) can induce unique quantum phenomena such as topological insulators, the Rashba effect, or p-wave superconductivity. Combining these three quantum phenomena into a single compound has important scientific implications. Here we report experimental observations of consecutive quantum phase transitions from a Rashba type topological trivial phase to topological insulator state then further proceeding to superconductivity in a SOI compound BiTeI tuned via pressures. The electrical resistivity measurement with V shape change signals the transition from a Rashba type topological trivial to a topological insulator phase at 2 GPa, which is caused by an energy gap close then reopen with band inverse. Superconducting transition appears at 8 GPa with a critical temperature TC of 5.3 K. Structure refinements indicate that the consecutive phase transitions are correlated to the changes in the Bi–Te bond and bond angle as function of pressures. The Hall Effect measurements reveal an intimate relationship between superconductivity and the unusual change in carrier density that points to possible unconventional superconductivity.

  13. Laser activated superconducting switch

    International Nuclear Information System (INIS)

    Wolf, A.A.

    1976-01-01

    A superconducting switch or bistable device is described consisting of a superconductor in a cryogen maintaining a temperature just below the transition temperature, having a window of the proper optical frequency band for passing a laser beam which may impinge on the superconductor when desired. The frequency of the laser is equal to or greater than the optical absorption frequency of the superconducting material and is consistent with the ratio of the gap energy of the switch material to Planck's constant, to cause depairing of electrons, and thereby normalize the superconductor. Some embodiments comprise first and second superconducting metals. Other embodiments feature the two superconducting metals separated by a thin film insulator through which the superconducting electrons tunnel during superconductivity

  14. Frontiers in Superconducting Materials

    CERN Document Server

    Narlikar, Anant V

    2005-01-01

    Frontiers in Superconducting Materials gives a state-of-the-art report of the most important topics of the current research in superconductive materials and related phenomena. It comprises 30 chapters written by renowned international experts in the field. It is of central interest to researchers and specialists in Physics and Materials Science, both in academic and industrial research, as well as advanced students. It also addresses electronic and electrical engineers. Even non-specialists interested in superconductivity might find some useful answers.

  15. Superconductivity and their applications

    OpenAIRE

    Roque, António

    2017-01-01

    Trabalho apresentado em International Conference on Renewable Energies and Power Quality (ICREPQ’17), 4 a 6 de Abril de 2017, Málaga, Espanha The research in the field of superconductivity has led to the synthesis of superconducting materials with features that allow you to expand the applicability of this kind of materials. Among the superconducting materials characteristics, the critical temperature of the superconductor is framing the range and type of industrial applications that can b...

  16. Surface and Superconductivity

    Science.gov (United States)

    Gor'kov, L. P.

    2006-07-01

    Experiments reveal the existence of metallic bands at surfaces of metals and insulators. The bands can be doped externally. We review properties of surface superconductivity that may set up in such bands at low temperatures and various means of superconductivity defection. The fundamental difference as compared to the ordinary superconductivity in metals, besides its two-dimensionality lies in the absence of the center of space inversion. This results in mixing between the singlet and triplet channels of the Cooper pairing.

  17. High-Temperature Superconductivity

    Science.gov (United States)

    Tanaka, Shoji

    2006-12-01

    A general review on high-temperature superconductivity was made. After prehistoric view and the process of discovery were stated, the special features of high-temperature superconductors were explained from the materials side and the physical properties side. The present status on applications of high-temperature superconductors were explained on superconducting tapes, electric power cables, magnets for maglev trains, electric motors, superconducting quantum interference device (SQUID) and single flux quantum (SFQ) devices and circuits.

  18. Superconductivity and its application

    International Nuclear Information System (INIS)

    Spadoni, M.

    1988-01-01

    This paper, after a short introduction to superconductivity and to multifilamentary superconducting composites is aiming to review the state of the art and the future perspective of some of the applications of the superconducting materials. The main interest is focussed to large scale applications like, for istance, magnets for accelerators or fusion reactors, superconducting system for NMR thomography, etc. A short paragraph is dedicated to applications for high sensitivity instrumentation. The paper is then concluded by some considerations about the potentialities of the newly discovered high critical temperature materials

  19. Superconductivity in power engineering

    International Nuclear Information System (INIS)

    1989-01-01

    This proceedings volume presents 24 conference papers and 15 posters dealing with the following aspects: 1) Principles and elementary aspects of high-temperature superconductivity (3 plenary lectures); 2) Preparation, properties and materials requirements of metallic or oxide superconductors (critical current behaviour, soldered joints, structural studies); 3) Magnet technology (large magnets for thermonuclear fusion devices; magnets for particle accelerators and medical devices); 4) Magnetic levitation and superconductivity; 5) Cryogenics; 6) Energy storage systems using superconducting coils (SMES); 7) Superconducting power transmission cables, switches, transformers, and generator systems for power plant; 8) Supporting activities, industrial aspects, patents. There are thirty-eight records in the ENERGY database relating to individual conference papers. (MM) [de

  20. Superconducting linear accelerator cryostat

    International Nuclear Information System (INIS)

    Ben-Zvi, I.; Elkonin, B.V.; Sokolowski, J.S.

    1984-01-01

    A large vertical cryostat for a superconducting linear accelerator using quarter wave resonators has been developed. The essential technical details, operational experience and performance are described. (author)

  1. Magnetic and Superconducting Materials at High Pressures

    Energy Technology Data Exchange (ETDEWEB)

    Struzhkin, Viktor V. [Carnegie Inst. of Washington, Washington, DC (United States)

    2015-03-24

    The work concentrates on few important tasks in enabling techniques for search of superconducting compressed hydrogen compounds and pure hydrogen, investigation of mechanisms of high-Tc superconductivity, and exploring new superconducting materials. Along that route we performed several challenging tasks, including discovery of new forms of polyhydrides of alkali metal Na at very high pressures. These experiments help us to establish the experimental environment that will provide important information on the high-pressure properties of hydrogen-rich compounds. Our recent progress in RIXS measurements opens a whole field of strongly correlated 3d materials. We have developed a systematic approach to measure major electronic parameters, like Hubbard energy U, and charge transfer energy Δ, as function of pressure. This technique will enable also RIXS studies of magnetic excitations in iridates and other 5d materials at the L edge, which attract a lot of interest recently. We have developed new magnetic sensing technique based on optically detected magnetic resonance from NV centers in diamond. The technique can be applied to study superconductivity in high-TC materials, to search for magnetic transitions in strongly correlated and itinerant magnetic materials under pressure. Summary of Project Activities; development of high-pressure experimentation platform for exploration of new potential superconductors, metal polyhydrides (including newly discovered alkali metal polyhydrides), and already known superconductors at the limit of static high-pressure techniques; investigation of special classes of superconducting compounds (high-Tc superconductors, new superconducting materials), that may provide new fundamental knowledge and may prove important for application as high-temperature/high-critical parameter superconductors; investigation of the pressure dependence of superconductivity and magnetic/phase transformations in 3d transition metal compounds, including

  2. Superconducting wire turns to electrical power

    CERN Document Server

    Sargent, P

    2003-01-01

    Two years after the discovery that magnesium diboride is a superconductor, engineers and entrepreneurs are keen to transform its properties into profit. The discovery of superconductivity at 39 K in the metallic compound magnesium diboride two years ago created quite a stir. Since then, physicists and chemists have come a long way in understanding the curious set of circumstances that lead to such a high critical temperature in this widely available material. At the same time, metallurgists, engineers and entrepreneurs have been focusing on the commercial potential of magnesium diboride as superconducting wire, which was the subject of a one-day meeting in Cambridge, UK, in April. Superconducting wire made from magnesium diboride could make 'second- generation' electrical machines commercially viable. (U.K.)

  3. Superconducting elliptical cavities

    CERN Document Server

    Sekutowicz, J K

    2011-01-01

    We give a brief overview of the history, state of the art, and future for elliptical superconducting cavities. Principles of the cell shape optimization, criteria for multi-cell structures design, HOM damping schemes and other features are discussed along with examples of superconducting structures for various applications.

  4. Large superconducting magnets

    CERN Document Server

    Pérot, J

    1981-01-01

    Discusses the use of large superconducting magnets in the areas of particle physics, thermonuclear fusion, and magnetohydrodynamics. In addition to considering the physics of the superconducting state, the article considers machines such as BEBC (Big European Bubble Chamber) at CERN, the LINAC at SLAC and possible Tokamak applications. The future application of superconductors to high speed trains is discussed. (0 refs).

  5. Superconducting cavities for LEP

    CERN Multimedia

    CERN PhotoLab

    1983-01-01

    Above: a 350 MHz superconducting accelerating cavity in niobium of the type envisaged for accelerating electrons and positrons in later phases of LEP. Below: a small 1 GHz cavity used for investigating the surface problems of superconducting niobium. Albert Insomby stays on the right. See Annual Report 1983 p. 51.

  6. The superconducting phases of UPt3

    Science.gov (United States)

    Joynt, Robert; Taillefer, Louis

    2002-01-01

    The heavy-fermion compound UPt3 is the first compelling example of a superconductor with an order parameter of unconventional symmetry. To this day, it is the only unambiguous case of multiple superconducting phases. Twenty years of experiment and theory on the superconductivity of UPt3 are reviewed, with the aim of accounting for the multicomponent phase diagram and identifying the superconducting phases. First, the state above the superconducting critical temperature at Tc=0.5 K is briefly described: de Haas-van Alphen and other measurements demonstrate that this state is a Fermi liquid, with degeneracy fully achieved at Tc. This implies that the usual BCS theory of superconductivity should hold, although the strong magnetic interactions suggest the possibility of an unconventional superconducting order parameter. The role of the weak antiferromagnetic order below TN=5 K in causing phase multiplicity is examined. A comprehensive analysis of which superconducting states are possible is given, and the theoretical basis for each of the main candidates is considered. The behavior of various properties at low temperature (Tnodes in the superconducting gap function of all three phases. In particular, the low-temperature low-field phase has a gap with a line node in the basal plane and point nodes along the hexagonal c axis. The phase diagram in the magnetic-field-temperature plane has been determined in detail by ultrasound and thermodynamic measurements. Experiments under pressure indicate a coupling between antiferromagnetism and superconductivity and provide additional clues about the order parameter. Theoretically, Ginzburg-Landau theory is the tool that elucidates the phase diagram, while calculations of the temperature and field dependence of physical quantities have been used to compare different order parameters to experiment. On balance, the data point to a two-component order parameter belonging to either the E1g or the E2u representation, with degeneracy

  7. Modern aspects of Josephson dynamics and superconductivity electronics

    CERN Document Server

    Askerzade, Iman; Cantürk, Mehmet

    2017-01-01

    In this book new experimental investigations of properties of Josephson junctions and systems are explored with the help of recent developments in superconductivity. The theory of the Josephson effect is presented taking into account the influence of multiband and anisotropy effects in new superconducting compounds. Anharmonicity effects in current-phase relation on Josephson junctions dynamics are discussed. Recent studies in analogue and digital superconductivity electronics are presented. Topics of special interest include resistive single flux quantum logic in digital electronics. Application of Josephson junctions in quantum computing as superconducting quantum bits are analyzed. Particular attention is given to understanding chaotic behaviour of Josephson junctions and systems. The book is written for graduate students and researchers in the field of applied superconductivity.

  8. Qubit compatible superconducting interconnects

    Science.gov (United States)

    Foxen, B.; Mutus, J. Y.; Lucero, E.; Graff, R.; Megrant, A.; Chen, Yu; Quintana, C.; Burkett, B.; Kelly, J.; Jeffrey, E.; Yang, Yan; Yu, Anthony; Arya, K.; Barends, R.; Chen, Zijun; Chiaro, B.; Dunsworth, A.; Fowler, A.; Gidney, C.; Giustina, M.; Huang, T.; Klimov, P.; Neeley, M.; Neill, C.; Roushan, P.; Sank, D.; Vainsencher, A.; Wenner, J.; White, T. C.; Martinis, John M.

    2018-01-01

    We present a fabrication process for fully superconducting interconnects compatible with superconducting qubit technology. These interconnects allow for the three dimensional integration of quantum circuits without introducing lossy amorphous dielectrics. They are composed of indium bumps several microns tall separated from an aluminum base layer by titanium nitride which serves as a diffusion barrier. We measure the whole structure to be superconducting (transition temperature of 1.1 K), limited by the aluminum. These interconnects have an average critical current of 26.8 mA, and mechanical shear and thermal cycle testing indicate that these devices are mechanically robust. Our process provides a method that reliably yields superconducting interconnects suitable for use with superconducting qubits.

  9. Superconducting wind turbine generators

    DEFF Research Database (Denmark)

    Abrahamsen, Asger Bech; Mijatovic, Nenad; Seiler, Eugen

    2010-01-01

    We have examined the potential of 10 MW superconducting direct drive generators to enter the European offshore wind power market and estimated that the production of about 1200 superconducting turbines until 2030 would correspond to 10% of the EU offshore market. The expected properties of future...... offshore turbines of 8 and 10 MW have been determined from an up-scaling of an existing 5 MW turbine and the necessary properties of the superconducting drive train are discussed. We have found that the absence of the gear box is the main benefit and the reduced weight and size is secondary. However......, the main challenge of the superconducting direct drive technology is to prove that the reliability is superior to the alternative drive trains based on gearboxes or permanent magnets. A strategy of successive testing of superconducting direct drive trains in real wind turbines of 10 kW, 100 kW, 1 MW and 10...

  10. Superconductivity and the Periodic Table

    International Nuclear Information System (INIS)

    Chapnik, I.M.

    1985-01-01

    In view of the inability of the present theory of superconductivity to make reliable predictions for the magnitude of Tsub(c) it seems useful to search for empirical relationships between the composition of the compound and the Tsub(c) value. Table I gives a list of the available Tsub(c) data for transition metals (TM) having from 3 to 9 outer electrons and Tsub(c) data for non-transition elements (NTE) of groups IIB, IIIB and IVB, including data for amorphous (Am) structures and structures (marked by triangles) obtained at high pressures. The analogous metals have therefore the same structure. In Tables II to IV the Tsub(c) data are presented for analogous compounds of NTE from IB - VIB group. Conclusions are presented. (author)

  11. Superconductivity in aromatic hydrocarbons

    Energy Technology Data Exchange (ETDEWEB)

    Kubozono, Yoshihiro, E-mail: kubozono@cc.okayama-u.ac.jp [Research Laboratory for Surface Science, Okayama University, Okayama 700-8530 (Japan); Research Center of New Functional Materials for Energy Production, Storage and Transport, Okayama University, Okayama 700-8530 (Japan); Japan Science and Technology Agency, ACT-C, Kawaguchi 332-0012 (Japan); Goto, Hidenori; Jabuchi, Taihei [Research Laboratory for Surface Science, Okayama University, Okayama 700-8530 (Japan); Yokoya, Takayoshi [Research Laboratory for Surface Science, Okayama University, Okayama 700-8530 (Japan); Research Center of New Functional Materials for Energy Production, Storage and Transport, Okayama University, Okayama 700-8530 (Japan); Kambe, Takashi [Department of Physics, Okayama University, Okayama 700-8530 (Japan); Sakai, Yusuke; Izumi, Masanari; Zheng, Lu; Hamao, Shino; Nguyen, Huyen L.T. [Research Laboratory for Surface Science, Okayama University, Okayama 700-8530 (Japan); Sakata, Masafumi; Kagayama, Tomoko; Shimizu, Katsuya [Center of Science and Technology under Extreme Conditions, Osaka University, Osaka 560-8531 (Japan)

    2015-07-15

    Highlights: • Aromatic superconductor is one of core research subjects in superconductivity. Superconductivity is observed in certain metal-doped aromatic hydrocarbons. Some serious problems to be solved exist for future advancement of the research. This article shows the present status of aromatic superconductors. - Abstract: ‘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 (K{sub x}picene, five benzene rings). Its superconducting transition temperatures (T{sub c}’s) were 7 and 18 K. Recently, we found a new superconducting K{sub x}picene phase with a T{sub c} as high as 14 K, so we now know that K{sub x}picene possesses multiple superconducting phases. Besides K{sub x}picene, we discovered new superconductors such as Rb{sub x}picene and Ca{sub x}picene. A most serious problem is that the shielding fraction is ⩽15% for K{sub x}picene and Rb{sub x}picene, 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 T{sub c} that is clearly

  12. Superconductivity and electrical resistivity in alkali metal doped ...

    Indian Academy of Sciences (India)

    Unknown

    Fullerenes; alkali-C60 phonon; on-ball-C60 phonon; pressure effect; electrical resistivity. 1. Introduction. Buckminsterfullerenes are known to make compounds with alkali metals intensively studied mainly due to superconductivity and the variation of compounds (Hebard et al 1991; Holczer et al 1991; Tanigaki et al 1991).

  13. Magnetic nesting and co-existence of ferromagnetism and superconductivity

    International Nuclear Information System (INIS)

    Elesin, V.F.; Kapaev, V.V.; Kopaev, Yu.V.

    2004-01-01

    In the case of providing for the magnetic nesting conditions of the electron spin dispersion law the co-existence of ferromagnetism and superconductivity is possible by any high magnetization. The co-existence of ferromagnetism and superconductivity in the layered cuprate compounds of the RuSr 2 GdCu 2 O 8 -type is explained on this basis, wherein due to the nonstrict provision of the magnetic nesting condition there exists the finite but sufficiently high critical magnetization [ru

  14. Introduction to superconductivity

    CERN Document Server

    Darriulat, Pierre

    1998-01-01

    The lecture series will address physicists, such as particle and nuclear physicists, familiar with non-relativistic quantum mechanics but not with solid state physics. The aim of this introduction to low temperature superconductivity is to give sufficient bases to the student for him/her to be able to access the scientific literature on this field. The five lectures will cover the following topics : 1. Normal metals, free electron gas, chambers equation. 2. Cooper pairs, the BCS ground state, quasi particle excitations. 3. DC superconductivity, Meissner state, dirty superconductors.4. Self consistent approach, Ginsburg Landau equations, Abrikosov fluxon lattice. 5. Josephson effects, high temperature superconductivity.

  15. Superconducting tin core fiber

    Energy Technology Data Exchange (ETDEWEB)

    Homa, Daniel; Liang, Yongxuan; Hill, Cary; Kaur, Gurbinder; Pickrell, Gary [Virginia Polytechnic Institute and State University, Department of Materials Science and Engineering, Blacksburg, VA (United States)

    2014-11-13

    In this study, we demonstrated superconductivity in a fiber with a tin core and fused silica cladding. The fibers were fabricated via a modified melt-draw technique and maintained core diameters ranging from 50-300 microns and overall diameters of 125-800 microns. Superconductivity of this fiber design was validated via the traditional four-probe test method in a bath of liquid helium at temperatures on the order of 3.8 K. The synthesis route and fiber design are perquisites to ongoing research dedicated all-fiber optoelectronics and the relationships between superconductivity and the material structures, as well as corresponding fabrication techniques. (orig.)

  16. Superconducting tin core fiber

    International Nuclear Information System (INIS)

    Homa, Daniel; Liang, Yongxuan; Hill, Cary; Kaur, Gurbinder; Pickrell, Gary

    2015-01-01

    In this study, we demonstrated superconductivity in a fiber with a tin core and fused silica cladding. The fibers were fabricated via a modified melt-draw technique and maintained core diameters ranging from 50-300 microns and overall diameters of 125-800 microns. Superconductivity of this fiber design was validated via the traditional four-probe test method in a bath of liquid helium at temperatures on the order of 3.8 K. The synthesis route and fiber design are perquisites to ongoing research dedicated all-fiber optoelectronics and the relationships between superconductivity and the material structures, as well as corresponding fabrication techniques. (orig.)

  17. The chronicle of superconductivity

    International Nuclear Information System (INIS)

    Bassalo, J.M.F.

    1981-01-01

    The chronicle of the superconductivity is shown, since the first observation made of Kamerlingh-Onnes, in the begining of our century about superconductivity effects, by describing several models and theories made by the physicists, by trying to explain the phenomenons referred about supercurrent, up to the modern BCS Theory. Our fundamental purpose rather than to make a historical-philosophical evolution about the superconductivity is only to make a sequence as who made what, when and how, by using the Solla-Price meaning. (Author) [pt

  18. Superconductivity in doped insulators

    International Nuclear Information System (INIS)

    Emery, V.J.; Kivelson, S.A.

    1995-01-01

    It is shown that many synthetic metals, including high temperature superconductors are ''bad metals'', with such a poor conductivity that the usual meanfield theory of superconductivity breaks down because of anomalously large classical and quantum fluctuations of the phase of the superconducting order parameter. It is argued that the supression of a first order phase transition (phase separation) by the long-range Coulomb interaction leads to high temperature superconductivity accompanied by static or dynamical charge inhomogeneIty. Evidence in support of this picture for high temperature superconductors is described

  19. Superconducting materials and magnets

    International Nuclear Information System (INIS)

    1991-04-01

    The Technical Committee Meeting on Superconducting Materials and Magnets was convened by the IAEA and held by invitation of the Japanese government on September 4-6, 1989 in Tokyo. The meeting was hosted by the National Research Institute for Metals. Topics of the conference related to superconducting magnets and technology with particular application to fusion and the superconducting supercollider. Technology using both high and low-temperature superconductors was discussed. This document is a compendium of the papers presented at the meeting. Refs, figs and tabs

  20. 'Speedy' superconducting circuits

    International Nuclear Information System (INIS)

    Holst, T.

    1994-01-01

    The most promising concept for realizing ultra-fast superconducting digital circuits is the Rapid Single Flux Quantum (RSFQ) logic. The basic physical principle behind RSFQ logic, which include the storage and transfer of individual magnetic flux quanta in Superconducting Quantum Interference Devices (SQUIDs), is explained. A Set-Reset flip-flop is used as an example of the implementation of an RSFQ based circuit. Finally, the outlook for high-temperature superconducting materials in connection with RSFQ circuits is discussed in some details. (au)

  1. Study of some superconducting and magnetic materials on high T sub c oxide superconductors

    Science.gov (United States)

    Wu, M. K.

    1987-01-01

    On the basis of existing data it appears that the high-temperature superconductivity above 77 K reported here, occurs only in compound systems consisting of a phase other than the K2NiF4 phase. A narrow superconducting transition was obtained with T sub c0 = 98 K and T sub c1 = 94 K in Y-Ba-Cu-O (YBCO). Preliminary results indicate that YBCO is rather different from the layered LaBCO, LaSCO, and LaCCO. While electron-photon interaction cannot be absent from this compound system, nonconventional enhanced superconducting interactions due to interfaces, Resonating Valence Bond (RVB) states, or even a superconducting state beyond the BCS framework, may be required to account for the high T sub c in YBCO. It is believed that study of the possible subtle correlation between magnetism and superconductivity will definitely provide important insight into the superconducting mechanism in YBCO and other oxides.

  2. Superconducting Technology Assessment

    National Research Council Canada - National Science Library

    2005-01-01

    This Superconducting Technology Assessment (STA) has been conducted by the National Security Agency to address the fundamental question of a potential replacement for silicon complementary metal oxide semiconductor (CMOS...

  3. Superconductivity and its devices

    International Nuclear Information System (INIS)

    Forbes, D.S.

    1981-01-01

    Among the more important developments that are discussed are cryotrons, superconducting motors and generators, and high-field magnets. Cryotrons will create faster and more economical computer systems. Superconducting motors and generators will cost much less to build than conventional electric generators and cut fuel consumption. Moreover, high-field magnets are being used to confine plasma in connection with nuclear fusion. Superconductors have a vital role to play in all of these developments. Most importantly, though, are the magnetic properties of superconductivity. Superconducting magnets are an integral part of nuclear fusion. In addition, high-field magnets are necessary in the use of accelerators, which are needed to study the interactions between elementary particles

  4. Superconductivity: Heike's heritage

    NARCIS (Netherlands)

    van der Marel, D.; Golden, M.

    2011-01-01

    A century ago, Heike Kamerlingh Onnes discovered superconductivity. And yet, despite the conventional superconductors being understood, the list of unconventional superconductors is growing — for which unconventional theories may be required.

  5. Magnetic and superconducting nanowires

    DEFF Research Database (Denmark)

    Piraux, L.; Encinas, A.; Vila, L.

    2005-01-01

    magnetic and superconducting nanowires. Using different approaches entailing measurements on both single wires and arrays, numerous interesting physical properties have been identified in relation to the nanoscopic dimensions of these materials. Finally, various novel applications of the nanowires are also...

  6. Industrial applied superconductivity

    International Nuclear Information System (INIS)

    Sabrie, J.L.

    1984-01-01

    This paper reviews the main applications of superconductivity in D.C. in variable current and in A.C. The existing markets are now worth the effort of producing commercial superconductors and of developing applications [fr

  7. Superconducting Wind Turbine Generators

    OpenAIRE

    Yunying Pan; Danhzen Gu

    2016-01-01

    Wind energy is well known as a renewable energy because its clean and less polluted characteristic, which is the foundation of development modern wind electricity. To find more efficient wind turbine is the focus of scientists around the world. Compared from conventional wind turbines, superconducting wind turbine generators have advantages at zero resistance, smaller size and lighter weight. Superconducting wind turbine will inevitably become the main trends in this area. This paper intends ...

  8. Superconducting Fullerene Nanowhiskers

    Directory of Open Access Journals (Sweden)

    Yoshihiko Takano

    2012-04-01

    Full Text Available We synthesized superconducting fullerene nanowhiskers (C60NWs by potassium (K intercalation. They showed large superconducting volume fractions, as high as 80%. The superconducting transition temperature at 17 K was independent of the K content (x in the range between 1.6 and 6.0 in K-doped C60 nanowhiskers (KxC60NWs, while the superconducting volume fractions changed with x. The highest shielding fraction of a full shielding volume was observed in the material of K3.3C60NW by heating at 200 °C. On the other hand, that of a K-doped fullerene (K-C60 crystal was less than 1%. We report the superconducting behaviors of our newly synthesized KxC60NWs in comparison to those of KxC60 crystals, which show superconductivity at 19 K in K3C60. The lattice structures are also discussed, based on the x-ray diffraction (XRD analyses.

  9. Electron pairing without superconductivity

    Science.gov (United States)

    Levy, Jeremy

    Strontium titanate (SrTiO3) is the first and best known superconducting semiconductor. It exhibits an extremely low carrier density threshold for superconductivity, and possesses a phase diagram similar to that of high-temperature superconductors--two factors that suggest an unconventional pairing mechanism. Despite sustained interest for 50 years, direct experimental insight into the nature of electron pairing in SrTiO3 has remained elusive. Here we perform transport experiments with nanowire-based single-electron transistors at the interface between SrTiO3 and a thin layer of lanthanum aluminate, LaAlO3. Electrostatic gating reveals a series of two-electron conductance resonances--paired electron states--that bifurcate above a critical pairing field Bp of about 1-4 tesla, an order of magnitude larger than the superconducting critical magnetic field. For magnetic fields below Bp, these resonances are insensitive to the applied magnetic field; for fields in excess of Bp, the resonances exhibit a linear Zeeman-like energy splitting. Electron pairing is stable at temperatures as high as 900 millikelvin, well above the superconducting transition temperature (about 300 millikelvin). These experiments demonstrate the existence of a robust electronic phase in which electrons pair without forming a superconducting state. Key experimental signatures are captured by a model involving an attractive Hubbard interaction that describes real-space electron pairing as a precursor to superconductivity. Support from AFOSR, ONR, ARO, NSF, DOE and NSSEFF is gratefully acknowledged.

  10. Emergent Higgsless Superconductivity

    Directory of Open Access Journals (Sweden)

    Cristina Diamantini M.

    2017-01-01

    Full Text Available We present a new Higgsless model of superconductivity, inspired from anyon superconductivity but P- and T-invariant and generalizable to any dimension. While the original anyon superconductivity mechanism was based on incompressible quantum Hall fluids as average field states, our mechanism involves topological insulators as average field states. In D space dimensions it involves a (D-1-form fictitious pseudovector gauge field which originates from the condensation of topological defects in compact lowenergy effective BF theories. There is no massive Higgs scalar as there is no local order parameter. When electromagnetism is switched on, the photon acquires mass by the topological BF mechanism. Although the charge of the gapless mode (2 and the topological order (4 are the same as those of the standard Higgs model, the two models of superconductivity are clearly different since the origins of the gap, reflected in the high-energy sectors are totally different. In 2D thi! s type of superconductivity is explicitly realized as global superconductivity in Josephson junction arrays. In 3D this model predicts a possible phase transition from topological insulators to Higgsless superconductors.

  11. Lattice parameters guide superconductivity in iron-arsenides

    International Nuclear Information System (INIS)

    Konzen, Lance M N; Sefat, Athena S

    2017-01-01

    The discovery of superconducting materials has led to their use in technological marvels such as magnetic-field sensors in MRI machines, powerful research magnets, short transmission cables, and high-speed trains. Despite such applications, the uses of superconductors are not widespread because they function much below room-temperature, hence the costly cooling. Since the discovery of Cu- and Fe-based high-temperature superconductors (HTS), much intense effort has tried to explain and understand the superconducting phenomenon. While no exact explanations are given, several trends are reported in relation to the materials basis in magnetism and spin excitations. In fact, most HTS have antiferromagnetic undoped ‘parent’ materials that undergo a superconducting transition upon small chemical substitutions in them. As it is currently unclear which ‘dopants’ can favor superconductivity, this manuscript investigates crystal structure changes upon chemical substitutions, to find clues in lattice parameters for the superconducting occurrence. We review the chemical substitution effects on the crystal lattice of iron-arsenide-based crystals (2008 to present). We note that (a) HTS compounds have nearly tetragonal structures with a -lattice parameter close to 4 Å, and (b) superconductivity can depend strongly on the c -lattice parameter changes with chemical substitution. For example, a decrease in c -lattice parameter is required to induce ‘in-plane’ superconductivity. The review of lattice parameter trends in iron-arsenides presented here should guide synthesis of new materials and provoke theoretical input, giving clues for HTS. (topical review)

  12. Electron–phonon superconductivity in YIn3

    International Nuclear Information System (INIS)

    Billington, D; Llewellyn-Jones, T M; Maroso, G; Dugdale, S B

    2013-01-01

    First-principles calculations of the electron–phonon coupling were performed on the cubic intermetallic compound YIn 3 . The electron–phonon coupling constant was found to be λ ep = 0.42. Using the Allen–Dynes formula with a Coulomb pseudopotential of μ* = 0.10, a T c of approximately 0.77 K is obtained which is reasonably consistent with the experimentally observed temperature (between 0.8 and 1.1 K). The results indicate that conventional electron–phonon coupling is capable of producing the superconductivity in this compound. (paper)

  13. Superconductivity transformers in power systems

    International Nuclear Information System (INIS)

    Martini, L.; Bocchi, M.; De Nigris, M.; Morandi, A.; Trevisan, L.; Fabbri, M.; Ribani, P.; Negrini, F.

    2008-01-01

    Transformers in superconducting materials at high temperatures offer many advantages in economic, environmental and functional aspects, compared to traditional transformers. Are presented the potentials of superconducting transformers available, aspects of design and the international state of the art [it

  14. Fullerides - Superconductivity at the limit

    NARCIS (Netherlands)

    Palstra, Thomas T. M.

    The successful synthesis of highly crystalline Cs3C60, exhibiting superconductivity up to a record temperature for fullerides of 38 K, demonstrates a powerful synthetic route for investigating the origin of superconductivity in this class of materials.

  15. Rf superconducting devices

    International Nuclear Information System (INIS)

    Hartwig, W.H.; Passow, C.

    1975-01-01

    Topics discussed include (1) the theory of superconductors in high-frequency fields (London surface impedance, anomalous normal surface resistance, pippard nonlocal theory, quantum mechanical model, superconductor parameters, quantum mechanical calculation techniques for the surface, impedance, and experimental verification of surface impedance theories); (2) residual resistance (separation of losses, magnetic field effects, surface resistance of imperfect and impure conductors, residual loss due to acoustic coupling, losses from nonideal surfaces, high magnetic field losses, field emission, and nonlinear effects); (3) design and performance of superconducting devices (design considerations, materials and fabrication techniques, measurement of performance, and frequency stability); (4) devices for particle acceleration and deflection (advantages and problems of using superconductors, accelerators for fast particles, accelerators for particles with slow velocities, beam optical devices separators, and applications and projects under way); (5) applications of low-power superconducting resonators (superconducting filters and tuners, oscillators and detectors, mixers and amplifiers, antennas and output tanks, superconducting resonators for materials research, and radiation detection with loaded superconducting resonators); and (6) transmission and delay lines

  16. Superconducting Ferromagnetic Nanodiamond.

    Science.gov (United States)

    Zhang, Gufei; Samuely, Tomas; Xu, Zheng; Jochum, Johanna K; Volodin, Alexander; Zhou, Shengqiang; May, Paul W; Onufriienko, Oleksandr; Kačmarčík, Jozef; Steele, Julian A; Li, Jun; Vanacken, Johan; Vacík, Jiri; Szabó, Pavol; Yuan, Haifeng; Roeffaers, Maarten B J; Cerbu, Dorin; Samuely, Peter; Hofkens, Johan; Moshchalkov, Victor V

    2017-06-27

    Superconductivity and ferromagnetism are two mutually antagonistic states in condensed matter. Research on the interplay between these two competing orderings sheds light not only on the cause of various quantum phenomena in strongly correlated systems but also on the general mechanism of superconductivity. Here we report on the observation of the electronic entanglement between superconducting and ferromagnetic states in hydrogenated boron-doped nanodiamond films, which have a superconducting transition temperature T c ∼ 3 K and a Curie temperature T Curie > 400 K. In spite of the high T Curie , our nanodiamond films demonstrate a decrease in the temperature dependence of magnetization below 100 K, in correspondence to an increase in the temperature dependence of resistivity. These anomalous magnetic and electrical transport properties reveal the presence of an intriguing precursor phase, in which spin fluctuations intervene as a result of the interplay between the two antagonistic states. Furthermore, the observations of high-temperature ferromagnetism, giant positive magnetoresistance, and anomalous Hall effect bring attention to the potential applications of our superconducting ferromagnetic nanodiamond films in magnetoelectronics, spintronics, and magnetic field sensing.

  17. Superconductivity and ferromagnetism in nanomaterial NbSe2

    Science.gov (United States)

    Gill, Raminder

    2017-07-01

    Finding of superconductivity (SC) in ultra thin layer of Niobium diselenide (NbSe2) caught the attention of each condensed matter physicist in the era of nanotechnology. The coexistence of SC and magnetism have been a topic of interesting research in solid-state physics since the discovery of superconductivity. Ferromagnetism induced in any compound could destroy superconductivity by disturbing the cooper pairing of electrons of the atoms. The interplay between ferromagnetism (FM) and SC in nanomaterial NBSe2 impressed to study and to know the exact mechanism behind this coexistence which can lead to a very interesting research: superconductivity at room temperature. In this paper, I have theoretically studied the coexistence of SC and FM in NbSe2 and how this material could be useful in finding many high Tc nanomaterials.

  18. Superconductivity in Weyl semimetal candidate MoTe{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Qi, Yanpeng; Naumov, Pavel; Rajamathi, Catherine; Barkalov, Oleg; Wu, Shu-Chun; Shekhar, Chandra; Sun, Yan; Suess, Vicky; Schmidt, Marcus; Schwarz, Ulrich; Schnelle, Walter; Felser, Claudia; Medvedev, Sergey [Max Planck Institute for Chemical Physics of Solids, Dresden (Germany); Ali, Mazhar; Cava, Robert [Department of Chemistry, Princeton University, Princeton (United States); Hanfland, Michael [European Synchrotron Radiation Facility, Grenoble (France); Pippel, Eckhard; Werner, Peter; Hillebrand, Reinald; Parkin, Stuart [Max Planck Institute of Microstructure Physics, Halle (Germany); Foerster, Tobias; Kampert, Erik [Dresden High Magnetic Field Laboratory, Dresden (Germany); Yan, Binghai [Max Planck Institute for Chemical Physics of Solids, Dresden (Germany); Max Planck Institute for the Physics of Complex Systems, Dresden (Germany)

    2016-07-01

    In this work, we investigate the sister compound of WTe{sub 2}, MoTe{sub 2}, which is also predicted to be a Weyl semimetal and a quantum spin Hall insulator in bulk and monolayer form, respectively. We find that MoTe{sub 2} exhibits superconductivity with a resistive transition temperature T{sub c} of 0.1 K. The application of a small pressure is shown to dramatically enhance the T{sub c}, with a maximum value of 8.2 K being obtained at 11.7 GPa (a more than 80-fold increase in Tc). This yields a dome-shaped superconducting phase diagram. Further explorations into the nature of the superconductivity in this system may provide insights into the interplay between superconductivity and topological physics.

  19. Superconductive analogue of spin glasses

    International Nuclear Information System (INIS)

    Feigel'man, M.; Ioffe, L.; Vinokur, V.; Larkin, A.

    1987-07-01

    The properties of granular superconductors in magnetic fields, namely the existence of a new superconductive state analogue of the low-temperature superconductive state in spin glasses are discussed in the frame of the infinite-range model and the finite-range models. Experiments for elucidation of spin-glass superconductive state in real systems are suggested. 30 refs

  20. Superconductive Signal-Processing Circuits

    Science.gov (United States)

    1994-08-01

    September 1991. 13. P. H. Xiao, E. Charbon , A. Sangiovanni-Vincentelli, T. Van Duzer,and S.W. Whiteley, "INDEX: An inductance extractor for superconducting...APPLIED SUPERCONDUCTIVITY, VOL. 3, ,Q I, MARCH 1993 2629 INDEX: An Inductance Extractor for Superconducting Circuits P. H. Xiao, E. Charbon , A

  1. Interface high-temperature superconductivity

    Science.gov (United States)

    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.

  2. Nonlinear terahertz superconducting plasmonics

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Jingbo; Liang, Lanju; Jin, Biaobing, E-mail: bbjin@nju.edu.cn, E-mail: tonouchi@ile.osaka-u.ac.jp, E-mail: phwu@nju.edu.cn; Kang, Lin; Xu, Weiwei; Chen, Jian; Wu, Peiheng, E-mail: bbjin@nju.edu.cn, E-mail: tonouchi@ile.osaka-u.ac.jp, E-mail: phwu@nju.edu.cn [Research Institute of Superconductor Electronics (RISE), School of Electronic Science and Engineering, Nanjing University, Nanjing 210093 (China); Zhang, Caihong; Kawayama, Iwao; Murakami, Hironaru; Tonouchi, Masayoshi, E-mail: bbjin@nju.edu.cn, E-mail: tonouchi@ile.osaka-u.ac.jp, E-mail: phwu@nju.edu.cn [Institute of Laser Engineering, Osaka University, 2-6 Yamadaoka, Suita, Osaka 565-0871 (Japan); Wang, Huabing [Research Institute of Superconductor Electronics (RISE), School of Electronic Science and Engineering, Nanjing University, Nanjing 210093 (China); National Institute for Materials Science, Tsukuba 305-0047 (Japan)

    2014-10-20

    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.

  3. Applied Superconductivity Conference 2014

    CERN Document Server

    2015-01-01

    Energy Efficiency is a worldwide imperative driven by an increasing awareness of the need to conserve valuable natural resources. Superconductivity, the technology which revolutionized non-invasive medical imaging through MRI starting in the 1980’s, is one of the most promising enablers of energy efficiency in the 21st century. From energy efficient supercomputers to power generation, transmission, and storage, the spectrum of applications of superconductivity is broad in its reach and potential. As ASC comes to Charlotte, site of the hall of fame of NASCAR, our theme, “Race to Energy Efficiency,” is intended to inspire the world experts in superconductivity who will converge to Charlotte to present their latest results, exchange information, network, and plan and project the future breakthroughs.

  4. On anyon superconductivity--

    International Nuclear Information System (INIS)

    Chen, Y.-H.; Wilczek, F.; Witten, E.; Halperin, B.I.

    1989-01-01

    We investigate the statistical mechanics of a gas of fractional statistics particles in 2 + 1 dimensions. In the case of statistics very close to Fermi statistics (statistical parameter θ = π(1 - 1/n), for large n), the effect of the statistics is a weak attraction. Building upon earlier RPA calculation for the case n = 2, the authors argue that for large n perturbation theory is reliable and exhibits superfluidity (or superconductivity after coupling to electromagnetism). They describe the order parameter for this superconductng phase in terms of spontaneous breaking of commutativity of translations as opposed to the usual pairing order parameters. The vortices of the superconducting anyon gas are charged, and superconducting order parameters of the usual type vanish. They investigate the characteristic P and T violating phenomenology

  5. Connectivity and superconductivity

    CERN Document Server

    Rubinstein, Jacob

    2000-01-01

    The motto of connectivity and superconductivity is that the solutions of the Ginzburg--Landau equations are qualitatively influenced by the topology of the boundaries, as in multiply-connected samples. Special attention is paid to the "zero set", the set of the positions (also known as "quantum vortices") where the order parameter vanishes. The effects considered here usually become important in the regime where the coherence length is of the order of the dimensions of the sample. It takes the intuition of physicists and the awareness of mathematicians to find these new effects. In connectivity and superconductivity, theoretical and experimental physicists are brought together with pure and applied mathematicians to review these surprising results. This volume is intended to serve as a reference book for graduate students and researchers in physics or mathematics interested in superconductivity, or in the Schrödinger equation as a limiting case of the Ginzburg--Landau equations.

  6. Superconductivity for mass spectroscopy

    International Nuclear Information System (INIS)

    Ohkubo, Masataka

    2007-01-01

    Time-of-Flight Mass Spectroscopy (TOF-MS) with super-conducting detectors has two advantages over MS with conventional ion detectors. First, it is coverage for a very wide range of molecule weight over 1,000,000. Secondly, kinetic energies of accelerated molecules can be measured at impact events one by one. These unique features enable an ultimate detection efficiency of 100% for intact ions and a fragmentation analysis that is critical for top-down proteomics. Superconducting MS is expected to play a role in, for example, the detection of antigen-antibody complexes, which are important for medical diagnosis. In this paper, how superconductivity contributes to MS is described. (author)

  7. Superconducting super collider

    International Nuclear Information System (INIS)

    Limon, P.J.

    1987-01-01

    The Superconducting Super Collider is to be a 20 TeV per beam proton-proton accelerator and collider. Physically the SCC will be 52 miles in circumference and slightly oval in shape. The use of superconducting magnets instead of conventional cuts the circumference from 180 miles to the 52 miles. The operating cost of the SCC per year is estimated to be about $200-250 million. A detailed cost estimate of the project is roughly $3 billion in 1986 dollars. For the big collider ring, the technical cost are dominated by the magnet system. That is why one must focus on the cost and design of the magnets. Presently, the process of site selection is underway. The major R and D efforts concern superconducting dipoles. The magnets use niobium-titanium as a conductor stabilized in a copper matrix. 10 figures

  8. High pressure induced superconductivity

    Energy Technology Data Exchange (ETDEWEB)

    Amaya, K.; Shimizu, K

    2003-10-15

    We have developed complex extreme condition of very low temperature down to 30 mK and ultra high pressure exceeding 200 GPa by assembling compact diamond anvil cell (DAC) on a powerful {sup 3}He/{sup 4}He dilution refrigerator. We have also developed measuring techniques of electrical resistance, magnetization and optical measurement for the sample confined in the sample space of the DAC. Using the newly developed apparatus and techniques, we have searched for superconductivity in various materials under pressure. In this paper, we will shortly review our newly developed experimental apparatus and techniques and discuss a few examples of pressure induced superconductivity which were observed recently.

  9. Today's markets for superconductivity

    International Nuclear Information System (INIS)

    Anon.

    1988-01-01

    The worldwide market for superconductive products may exceed $1 billion in 1987. These products are expanding the frontiers of science, revolutionizing the art of medical diagnosis, and developing the energy technology of the future. In general, today's customers for superconductive equipment want the highest possible performance, almost regardless of cost. The products operate within a few degrees of absolute zero, and virtually all are fabricated from niobium or niobium alloys-so far the high-temperature superconductors discovered in 1986 and 1987 have had no impact on these markets. The industry shows potential and profound societal impact, even without the new materials

  10. Superconducting magnetic quadrupole

    Energy Technology Data Exchange (ETDEWEB)

    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.

  11. Superconducting cosmic strings

    International Nuclear Information System (INIS)

    Chudnovsky, E.M.; Field, G.B.; Spergel, D.N.; Vilenkin, A.

    1986-01-01

    Superconducting loops of string formed in the early Universe, if they are relatively light, can be an important source of relativistic particles in the Galaxy. They can be observed as sources of synchrotron radiation at centimeter wavelengths. We propose a string model for two recently discovered radio sources, the ''thread'' in the galactic center and the source G357.7-0.1, and predict that the filaments in these sources should move at relativistic speeds. We also consider superheavy superconducting strings, and the possibility that they be observed as extragalactic radio sources

  12. Gambling with Superconducting Fluctuations

    Science.gov (United States)

    Foltyn, Marek; Zgirski, Maciej

    2015-08-01

    Josephson junctions and superconducting nanowires, when biased close to superconducting critical current, can switch to a nonzero voltage state by thermal or quantum fluctuations. The process is understood as an escape of a Brownian particle from a metastable state. Since this effect is fully stochastic, we propose to use it for generating random numbers. We present protocol for obtaining random numbers and test the experimentally harvested data for their fidelity. Our work is prerequisite for using the Josephson junction as a tool for stochastic (probabilistic) determination of physical parameters such as magnetic flux, temperature, and current.

  13. Superconducting current generators

    International Nuclear Information System (INIS)

    Genevey, P.

    1970-01-01

    After a brief summary of the principle of energy storage and liberation with superconducting coils,two current generators are described that create currents in the range 600 to 1400 A, used for two storage experiments of 25 kJ and 50 kJ respectively. The two current generators are: a) a flux pump and b) a superconducting transformer. Both could be developed into more powerful units. The study shows the advantage of the transformer over the flux pump in order to create large currents. The efficiencies of the two generators are 95 per cent and 40 to 60 per cent respectively. (author) [fr

  14. Fabrication of superconducting wire using organometallic precursors and infiltration

    International Nuclear Information System (INIS)

    Lee, Y.J.

    1991-01-01

    Organometallic precursors from naphthenic acid and metal nitrates were used for the synthesis of YBCO oxide superconducting compounds. The characteristics of metal naphthenates as organometallic precursors were investigated by IR spectra, viscosity measurements, and infiltration. 123 superconducting compound obtained from 123 naphthenate showed a Tc of 90 degree K and a rather dense and elongated microstructure. Also, the melting behavior of Ba-cuprates which were used for 123 making was studied. A low-temperature melting process was developed to fabricate silver-sheathed superconducting wire with the powder-in-tube method; flowing argon gas is introduced to the system at 930-945 degree C to reduce the melting temperature of the 123 compound without silver sheath melting. It resulted in a 90 degree K Tc superconducting core with dense and locally aligned microstructure. SEM-EDS and XRD analysis, 4-probe resistance and Jc measurements, and carbon-content determinations were carried out to characterize the microstructure, grain alignment, and superconducting properties of the samples

  15. Effects of irradiation and mechanical stress on the superconducting properties of candidate magnet conductors

    International Nuclear Information System (INIS)

    Snead, C.L. Jr.; Luhman, T.

    1980-01-01

    The effects of radiation damage on the superconducting critical properties of candidate magnet materials are reviewed. Neutron, and charged-particle irradiation results are covered. The discussion is restricted to effects in NbTi and the A15-compound superconductors. The utility of these conductors in radiation fields is first explored by defining the magnitude of critical-property changes with the fluence of various irradiating particles. The physical mechanisms that couple the irradiation defects to the observed critical-property changes are discussed. Annealing/recovery data on irradiated materials are included where they pertain to the understanding of the physical mechanisms involved, and thereby to the desirability of magnet annealing in actual operating circumstances

  16. LHC superconducting strand

    CERN Multimedia

    Patrice Loiez

    1999-01-01

    This cross-section through a strand of superconducting matieral as used in the LHC shows the 8000 Niobium-Titanium filaments embedded like a honeycomb in copper. When cooled to 1.9 degrees above absolute zero in the LHC accelerator, these filaments will have zero resistance and so will carry a high electric current with no energy loss.

  17. Checking BEBC superconducting magnet

    CERN Multimedia

    CERN PhotoLab

    1974-01-01

    The superconducting coils of the magnet for the 3.7 m Big European Bubble Chamber (BEBC) had to be checked, see Annual Report 1974, p. 60. The photo shows a dismantled pancake. By December 1974 the magnet reached again the field design value of 3.5 T.

  18. Electrical Conduction and Superconductivity

    Indian Academy of Sciences (India)

    Superconductivity, the awe-inspiring word came into existence when KamerIingh Onnes (Box 1) discovered a new phenom- enon in 1911. When he cooled a sample of liquid metal mercury, it lost its electrical resistance at temperatures close to 0 K. Years of careful experimentation at Leiden preceded his success in the.

  19. LEP superconducting cavity

    CERN Multimedia

    1995-01-01

    Engineers work in a clean room on one of the superconducting cavities for the upgrade to the LEP accelerator, known as LEP-2. The use of superconductors allow higher electric fields to be produced so that higher beam energies can be reached.

  20. Superconducting Super Collider project

    International Nuclear Information System (INIS)

    Perl, M.L.

    1986-04-01

    The scientific need for the Superconducting Super Collider (SSC) is outlined, along with the history of the development of the SSC concept. A brief technical description is given of each of the main points of the SSC conceptual design. The construction cost and construction schedule are discussed, followed by issues associated with the realization of the SSC. 8 refs., 3 figs., 3 tabs

  1. Niobium superconducting cavity

    CERN Multimedia

    CERN PhotoLab

    1980-01-01

    This 5-cell superconducting cavity, made from bulk-Nb, stems from the period of general studies, not all directed towards direct use at LEP. This one is dimensioned for 1.5 GHz, the frequency used at CEBAF and also studied at Saclay (LEP RF was 352.2 MHz). See also 7908227, 8007354, 8209255, 8210054, 8312339.

  2. Superconducting electronics testing

    International Nuclear Information System (INIS)

    Moskowitz, P.A.; Guernsey, R.W.; Stasiak, J.W.; Flint, E.B.

    1983-01-01

    An I/O assembly has been designed and constructed to support the operation of superconducting circuitry. A system, previously described for chip testing, has been adapted for use with a Josephson technology system level experiment. The cryoinsert assembly, constructed of non-magnetic parts, provides 80 high frequency I/O lines between room temperature and 4.2 K. (author)

  3. High temperature superconductivity: Proceedings

    International Nuclear Information System (INIS)

    Bedell, K.S.; Coffey, D.; Meltzer, D.E.; Pines, D.; Schrieffer, J.R.

    1990-01-01

    This book is the result of a symposium at Los Alamos in 1989 on High Temperature Superconductivity. The topics covered include: phenomenology, quantum spin liquids, spin space fluctuations in the insulating and metallic phases, normal state properties, and numerical studies and simulations. (JF)

  4. Superconductivity : Controlling magnetism

    NARCIS (Netherlands)

    Golubov, Alexandre Avraamovitch; Kupriyanov, Mikhail Yu.

    Manipulation of the magnetic state in spin valve structures by superconductivity has now been achieved, opening a new route for the development of ultra-fast cryogenic memories. Spintronics is a rapidly developing field that allows insight into fundamental spin-dependent physical properties and the

  5. Superconducting magnets 1992

    International Nuclear Information System (INIS)

    1993-06-01

    This report discusses the following topics on Superconducting Magnets; SSC Magnet Industrialization; Collider Quadrupole Development; A Record-Setting Magnet; D20: The Push Beyond 10T; Nonaccelerator Applications; APC Materials Development; High-T c at Low Temperature; Cable and Cabling-Machine Development; and Analytical Magnet Design

  6. AC/RF Superconductivity

    Energy Technology Data Exchange (ETDEWEB)

    Ciovati, Gianluigi [JLAB

    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.

  7. MOCVD superconducting oxide films

    Science.gov (United States)

    Hirai, Toshio; Yamane, Hisanori

    1991-01-01

    Preparation of high- Tc superconducting oxide films by MOCVD, their films structure and superconducting properties are reviewed from the standpoint of "nano-composites" and "fine-composites". Y-Ba-Cu-O (YBCO) films formed on SrTiO 3(100) at 850°C showed a superconducting transition temperature with zero resistivity above 90 K. The maximum critical current density was 2.0×10 6 A/cm 2 at 77.3 K and 0 T, and 6.5×10 4 A/cm 2 at 77.3 K and 27 T. CuO and a-axis oriented YBCO grains were contained in the matrix of c-axis oriented YBCO. A transmission electron microscope observation revealed that inclusions of about 10-30 nm were embedded in the a- b plane of YBCO. MOCVD-YBCO films prepared on MgO(100) were used for superconducting devices. Some studies on the MOCVD films of Bi-Sr-Ca-Cu-O and Tl-Ba-Ca-Cu-O are also reviewed.

  8. ISR Superconducting Quadrupoles

    CERN Multimedia

    1977-01-01

    Michel Bouvier is preparing for curing the 6-pole superconducting windings inbedded in the cylindrical wall separating liquid helium from vacuum in the quadrupole aperture. The heat for curing the epoxy glue was provided by a ramp of infrared lamps which can be seen above the slowly rotating cylinder. See also 7703512X, 7702690X.

  9. Electrical Conduction and Superconductivity

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 8; Issue 9. Electrical Conduction and Superconductivity. Suresh V Vettoor. General Article Volume 8 Issue 9 September 2003 pp 41-48. Fulltext. Click here to view fulltext PDF. Permanent link: http://www.ias.ac.in/article/fulltext/reso/008/09/0041-0048 ...

  10. Structural studies of type N superconductive compounds: R{sub 2-x}Ce{sub x}CuO{sub 4{+-}{delta}} (R = Gd, Eu, Sm, Nd, Pr); influences of chemical treatments on physical properties; Etudes structurales des composes supraconducteurs de type N: R{sub 2-x}Ce{sub x}CuO{sub 4{+-}{delta}} (R = Gd, Eu, Sm, Nd, Pr); influences des traitements chimiques sur les proprietes physiques

    Energy Technology Data Exchange (ETDEWEB)

    Vigoureux, P.

    1995-06-01

    Different chemical treatments of R{sub 2-x}Ce{sub x}CuO{sub 4{+-}{delta}} compounds monocrystals (gadolinium, europium, samarium, neodymium and praseodymium cuprates) modify their physical properties especially their superconductive properties. The presented chemical treatments are: the substitution of the trivalent rare earth element R by an other trivalent lanthanide, its substitution by tetravalent cerium, and heat treatment under low oxygen pressure. After these chemical treatments, structural modifications are observed by neutrons and X-rays diffraction, and allow to precise their actions: size effect of the rare earth element on the deformation of the CuO{sub 2} planes, links between deformation and superconductivity and magnetic properties. (A.B.). 394 refs/.

  11. Intermediate normal metal layers in superconducting circuitry

    International Nuclear Information System (INIS)

    Sweeney, M.F.; Gershenson, M.; Fleming, D.L.; Barta, R.E.

    1987-01-01

    This patent describes a superconducting device comprising a first superconducting layer, a junction layer on the first superconducting layer, an insulating layer on the first superconducting layer, at least one superconducting area on the junction layer surrounded by the insulator layer, superconducting connector pad means disposed over the superconducting area, and superconducting wire means electrically connected to the superconducting connector pad means. The improvement comprising a first metal layer is disposed over the insulator layer and intermediate the superconducting area. The connector pad means and a second metal layer are disposed between the connector pad means and the superconductor wire means. The first metal layer covers the superconducting area and the first and second metal layers are sufficiently thin to allow quantum mechanical tunneling between the connector pad means and the superconducting area and the connector pad means and the superconducting wire means, respectively

  12. Improvements in or relating to superconducting members and methods of manufacture thereof

    International Nuclear Information System (INIS)

    Madson, P.E.; Charlesworth, J.P.; Armstrong, D.

    1975-01-01

    Reference is made to superconducting materials having comparatively high critical temperatures and critical magnetic fields. Such materials include compounds of A15 crystal structure having the general formula A 3 B, where A is Nb or V and B is one or more of the elements Al, Ga, In, Si, Ge and Sn. A method for manufacturing such materials is described in BP 1 333 554. The present specification is concerned with 'stabilisation' of materials manufactured by the method described in the earlier specification. By 'stabilization' is here meant prrevention or reduction of the undesirable effects of sudden movement of magnetic flux, known as 'flux jumps'. Two methods of stabilization are combined in the same material, known respectively as 'filamentary stabilization', in which the superconducting material is present in the form of fine filaments in a normally conducting matrix, and 'dynamic stabilization', in which a proportion of the normally conducting matrix material takes the form of a material of high electrical conductivity, such as pure Cu. (G.B.)

  13. Alcoholic beverages induce superconductivity in FeTe1-xSx

    International Nuclear Information System (INIS)

    Deguchi, K; Kawasaki, Y; Ozaki, T; Tsuda, S; Yamaguchi, T; Takano, Y; Mizuguchi, Y

    2011-01-01

    We found that hot alcoholic beverages were effective in inducing superconductivity in FeTe 0.8 S 0.2 . Heating the FeTe 0.8 S 0.2 compound in various alcoholic beverages enhances the superconducting properties compared to a pure water-ethanol mixture as a control. Heating with red wine for 24 h leads to the largest shielding volume fraction of 62.4% and the highest zero resistivity temperature of 7.8 K. Some components present in alcoholic beverages, other than water and ethanol, have the ability to induce superconductivity in the FeTe 0.8 S 0.2 compound.

  14. Superconducting permanent magnets for high-temperature operation

    Czech Academy of Sciences Publication Activity Database

    Jirsa, Miloš; Muralidhar, M.

    2004-01-01

    Roč. 54, Suppl. D (2004), D441-D444 ISSN 0011-4626. [Czech and Slovak Conference on Magnetism. Košice, 12.07.2004-15.07.2004] Institutional research plan: CEZ:AV0Z1010914 Keywords : superconducting magnets * ternary LRE-123 compounds * mesoscopic defects Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.292, year: 2004

  15. Changes in the excitations related to the superconducting transition ...

    Indian Academy of Sciences (India)

    superconducting transition in V3Si. M YETHIRAJ. Bragg Institute, ANSTO, Lucas Heights, NSW 2234, Australia. E-mail: mohana.yethiraj@gmail.com. Abstract. In earlier studies of phonons in V3Si, a gradual softening of the (h h 0) branch was observed and attributed to the martensitic transition in this compound, which pre-.

  16. Changes in the excitations related to the superconducting transition ...

    Indian Academy of Sciences (India)

    In earlier studies of phonons in V3Si, a gradual softening of the (ℎ ℎ 0) branch was observed and attributed to the martensitic transition in this compound, which precedes the onset of superconductivity by a few degrees K. In this work, the temperature dependence of the transverse acoustic branch along the ℎ ℎ 0 direction ...

  17. A new quantum interferometer effect in superconducting oxide ceramics

    International Nuclear Information System (INIS)

    Chela Flores, J.; Shehata, L.N.

    1987-08-01

    On the basis of a phenomenological approach to type II high T c superconductivity, we suggest that in the lanthanum compounds the Mercereau effect for a coupled junction pair should display and ex-dependent shift in the period of modulation of the tunnelling current. (author). 14 refs

  18. Superconducting energy store

    International Nuclear Information System (INIS)

    Elsel, W.

    1986-01-01

    The advantages obtained by the energy store device according to the invention with a superconducting solenoid system consist of the fact that only relatively short superconducting forward and return leads are required, which are collected into cables as far as possible. This limits the coolant losses of the cables. Only one relatively expensive connecting part with a transition of its conductors from room temperature to a low temperature is required, which, like the normal conducting current switch, is easily accessible. As the continuation has to be cooled independently of the upper part solenoid, cooling of this continuation part can prevent the introduction of large quantities of heat into the connected part solenoid. Due to the cooling of the forward and return conductors of the connecting cable with the coolant of the lower part solenoid, there are relatively few separations between the coolant spaces of the part solenoids. (orig./MM) [de

  19. Superconducting Accelerator Magnets

    CERN Document Server

    Mess, K H; Wolff, S

    1996-01-01

    The main topic of the book are the superconducting dipole and quadrupole magnets needed in high-energy accelerators and storage rings for protons, antiprotons or heavy ions. The basic principles of low-temperature superconductivity are outlined with special emphasis on the effects which are relevant for accelerator magnets. Properties and fabrication methods of practical superconductors are described. Analytical methods for field calculation and multipole expansion are presented for coils without and with iron yoke. The effect of yoke saturation and geometric distortions on field quality is studied. Persistent magnetization currents in the superconductor and eddy currents the copper part of the cable are analyzed in detail and their influence on field quality and magnet performance is investigated. Superconductor stability, quench origins and propagation and magnet protection are addressed. Some important concepts of accelerator physics are introduced which are needed to appreciate the demanding requirements ...

  20. Statistical mechanics of superconductivity

    CERN Document Server

    Kita, Takafumi

    2015-01-01

    This book provides a theoretical, step-by-step comprehensive explanation of superconductivity for undergraduate and graduate students who have completed elementary courses on thermodynamics and quantum mechanics. To this end, it adopts the unique approach of starting with the statistical mechanics of quantum ideal gases and successively adding and clarifying elements and techniques indispensible for understanding it. They include the spin-statistics theorem, second quantization, density matrices, the Bloch–De Dominicis theorem, the variational principle in statistical mechanics, attractive interaction, and bound states. Ample examples of their usage are also provided in terms of topics from advanced statistical mechanics such as two-particle correlations of quantum ideal gases, derivation of the Hartree–Fock equations, and Landau’s Fermi-liquid theory, among others. With these preliminaries, the fundamental mean-field equations of superconductivity are derived with maximum mathematical clarity based on ...

  1. 2017 Gordon Conference on Superconductivity

    Energy Technology Data Exchange (ETDEWEB)

    Chubukov, Andrey [Univ. of Minnesota, Twin Cities, MN (United States)

    2017-11-14

    The DOE award was for a 2017 Gordon Research conference on Superconductivity (GRC). The objective of GRC is to interchange the information about the latest theoretical and experimental developments in the area of superconductivity and to select most perspective directions for future research in this area.The goal of the Gordon Conference on Superconductivity is to present and discuss the latest results in the field of modern superconductivity, discuss new ideas and new directions of research in the area. It is a long-standing tradition of the Gordon conference on Superconductivity that the vast majority of participants are junior scientists. Funding for the conference would primarily be used to support junior researchers, particularly from under-represented groups. We had more 10 female speakers, some of them junior researchers, and some funding was used to support these speakers. The conference was held together with Gordon Research Seminar on Superconductivity, where almost all speakers and participants were junior scientists.

  2. Vector superconductivity in cosmic strings

    International Nuclear Information System (INIS)

    Dvali, G.R.; Mahajan, S.M.

    1992-03-01

    We argue that in most realistic cases, the usual Witten-type bosonic superconductivity of the cosmic string is automatically (independent of the existence of superconducting currents) accompanied by the condensation of charged gauge vector bosons in the core giving rise to a new vector type superconductivity. The value of the charged vector condensate is related with the charged scalar expectation value, and vanishes only if the latter goes to zero. The mechanism for the proposed vector superconductivity, differing fundamentally from those in the literature, is delineated using the simplest realistic example of the two Higgs doublet standard model interacting with the extra cosmic string. It is shown that for a wide range of parameters, for which the string becomes scalarly superconducting, W boson condensates (the sources of vector superconductivity) are necessarily excited. (author). 14 refs

  3. Towards inducing superconductivity into graphene

    Science.gov (United States)

    Efetov, Dmitri K.

    dependent effective Debey temperature - the so-called Bloch-Gruneisen temperature theta BG. We also probe the transport properties of the high energy sub-bands in bilayer graphene by electrolyte gating. Furthermore we demonstrate that electrolyte gates can be used to drive intercalation reactions in graphite and present an all optical study of the reaction kinetics during the creation of the graphene derived graphite intercalation compound LiC 6, and show the general applicability of the electrolyte gates to other 2-dimensional materials such as thin films of complex oxides, where we demonstrate gating dependent conductance changes in the spin-orbit Mott insulator Sr 2IrO4. Another, entirely different approach to induce superconducting correlations into graphene is by bringing it into proximity to a superconductor. Although not intrinsic to graphene, Cooper pairs can leak in from the superconductor and exist in graphene in the form of phase-coherent electron-hole states, the so-called Andreev states. Here we demonstrate a new way of fabricating highly transparent graphene/superconductor junctions by vertical stacking of graphene and the type-II van der Waals superconductor NbSe2. Due to NbSe2's high upper critical field of Hc2=4T we are able to test a long proposed and yet not well understood regime, where proximity effect and quantum Hall effect coexist.

  4. UPt3, heavy fermions and superconductivity

    International Nuclear Information System (INIS)

    Visser, A. de.

    1986-01-01

    In this thesis an experimental study is presented of one of the heavy-fermion superconductors: UPt 3 (T c =0.5 K). The normal-state properties of this material are governed by pronounced spin-fluctuation effects. The unusual coexistence of spin-fluctuations and superconductivity is strongly suggestive for an unconventional type of superconductivity, mediated by spin-fluctuations instead of phonons, with the condensate formed out of odd-parity electron states. In the first chapter a general introduction is given to the field of the heavy-fermions. In the second chapter a theoretical background for the properties of UPt 3 is presented. Chapter 3 deals with the sample preparation and measuring techniques. In chapter 4 a series of experiments is presented on the normal-phase of UPt 3 , among which are studies of the specific heat, thermal expansion, sound velocity, magnetization, electrical resistivity, magnetoresistivity and magnetostriction. Also the influence of high-magnetic fields (35 T) and high-pressures (5 kbar) has been studied. The superconducting phase of UPt 3 has been discussed in chapter 5. In chapter 6 a series of pseudobinary U(Pt 1-x Pd x ) 3 compounds (x≤0.30) are studied. In the last chapter some final remarks and conclusions are presented. (Auth.)

  5. Development of portable superconducting bulk magnet system

    International Nuclear Information System (INIS)

    Saho, N.; Nishijima, N.; Tanaka, H.; Sasaki, A.

    2009-01-01

    Recently a magnetic drug delivery system (MDDS) has been developing to navigate magnetic seeded drugs around diseased parts of the human body. To improve the magnetic drug delivery performance, a portable high temperature superconducting (HTS) bulk magnet system with high magnetic fields has been developed. This magnet system mainly consists of small bulk high temperature superconductors and a compact cryocooler. The materials of the high temperature superconductor are rare earth 123 single domain compounds (Gd-Ba-Cu-O). The bulk magnet was activated successfully using field-cooling magnetization under the superconducting solenoid magnet. The magnetic flux densities at the surface of the vacuum chambers that contain bulk magnets reached 5.07 T and 6.76 T using the static magnetic fields of 6 T and 10 T superconducting solenoid magnets, respectively. A cryocooler cooled them to 38.1 K and 39.1 K. It was clarified that the magnetic gradient was approximately 10 T/m at a position located 50 mm from the surface of the vacuum chambers.

  6. Topological confinement and superconductivity

    Energy Technology Data Exchange (ETDEWEB)

    Al-hassanieh, Dhaled A [Los Alamos National Laboratory; Batista, Cristian D [Los Alamos National Laboratory

    2008-01-01

    We derive a Kondo Lattice model with a correlated conduction band from a two-band Hubbard Hamiltonian. This mapping allows us to describe the emergence of a robust pairing mechanism in a model that only contains repulsive interactions. The mechanism is due to topological confinement and results from the interplay between antiferromagnetism and delocalization. By using Density-Matrix-Renormalization-Group (DMRG) we demonstrate that this mechanism leads to dominant superconducting correlations in aID-system.

  7. Superconducting Ferromagnetic Nanodiamond

    Czech Academy of Sciences Publication Activity Database

    Zhang, G.; Samuely, T.; Xu, Z.; Jochum, J. K.; Volodin, A.; Zhou, S. Q.; May, P. W.; Onufriienko, O.; Kacmarik, J.; Steele, J. A.; Li, J.; Vanacken, J.; Vacík, Jiří; Szabo, P.; Yuan, H. F.; Roeffaers, M. B. J.; Cerbu, D.; Samuely, P.; Hofkens, J.; Moshchalkov, V.V.

    2017-01-01

    Roč. 11, č. 6 (2017), s. 5358-5366 ISSN 1936-0851 R&D Projects: GA ČR(CZ) GBP108/12/G108; GA MŠk LM2015056 Institutional support: RVO:61389005 Keywords : nanodiamond * superconductivity and ferromagnetism * spin fluctuations * giant positive magnetoresistance * anamalous Hall effect Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders OBOR OECD: Nano-materials (production and properties) Impact factor: 13.942, year: 2016

  8. Unconventional superconductivity near inhomogeneities

    Energy Technology Data Exchange (ETDEWEB)

    Poenicke, A.F.

    2008-01-25

    After the presentation of a quasi-classical theory the specific heat of Sr{sub 2}RuO{sub 4} is considered. Then tunneling spectroscopy on cuprate superconductors is discussed. Thereafter the subharmonic gap structure in d-wave superconductors is considered. Finally the application of the S-matrix in superconductivity is discussed with spin mixing, CrO{sub 2} as example, and an interface model. (HSI)

  9. Superconducting magnets and cryogenics

    International Nuclear Information System (INIS)

    Purcell, J.R.

    1975-01-01

    Several significant superconducting beam line magnet systems are being constructed in the U. S. These will demonstrate the practicability of superconductors in beam lines. It is now time to consider some of the more subtle engineering problems associated with these magnets in order to assure a ''next generation'' of highly usable magnets. This paper presents some engineering approaches to better magnets for the future. (U.S.)

  10. Superconducting Panofsky quadrupoles

    International Nuclear Information System (INIS)

    Harwood, L.H.

    1981-01-01

    A design for a rectangular aperture quadrupole magnet without pole-tips was introduced by Hand and Panofsky in 1959. This design was quite radical but simple to construct. Few magnets of this design were ever built because of the large power needed. With the advent of superconducting coils there has been a renewed interest in them. The mathematical basis, field characteristics, and present and future construction of these magnets are described

  11. Lighting up superconducting stripes

    Science.gov (United States)

    Ergeçen, Emre; Gedik, Nuh

    2018-02-01

    Cuprate superconductors display a plethora of complex phases as a function of temperature and carrier concentration, the understanding of which could provide clues into the mechanism of superconductivity. For example, when about one-eighth of the conduction electrons are removed from the copper oxygen planes in cuprates such as La2‑xBaxCuO4 (LBCO), the doped holes (missing electrons) organize into one-dimensional stripes (1). The bulk superconducting transition temperature (Tc) is greatly reduced, and just above Tc, electrical transport perpendicular to the planes (along the c axis) becomes resistive, but parallel to the copper oxygen planes, resistivity remains zero for a range of temperatures (2). It was proposed a decade ago (3) that this anisotropic behavior is caused by pair density waves (PDWs); superconducting Cooper pairs exist along the stripes within the planes but cannot tunnel to the adjacent layers. On page 575 of this issue, Rajasekaran et al. (4) now report detection of this state in LBCO using nonlinear reflection of high-intensity terahertz (THz) light.

  12. The origin of superconductivity

    Energy Technology Data Exchange (ETDEWEB)

    Fan, J.D., E-mail: jdfan3@cox.net [Chongqing Academy of Science and Technology, Chongqing (China); JD Duz Institute for Superconductivity, Baton Rouge, Louisiana (United States); Malozovsky, Y.M. [Southern University and A and M College, Baton Rouge, Louisiana (United States); JD Duz Institute for Superconductivity, Baton Rouge, Louisiana (United States)

    2013-10-15

    We have shown in the other article of ours, published in the same issue as this one and entitled “Superconductivity in a Fermi liquid: The role of electron-phonon interaction,” that the quasiparticle interaction is just the particle interaction with an opposite sign. In other words, the interaction between two quasielectrons in k- or momentum-space is attractive while the interaction between two electrons in real space is repulsive. Since the quasiparticles are responsible for all properties of a Fermi liquid, then investigations of behaviors of quasipartilces will be sufficient for one to understand the relevant properties of the system consisting of those quasiparticles (particles), Moreover, as shown in our earlier work [1,2], pairing of two quasiparticles in a spin singlet state due to the Coulomb interaction is well-reasoned without needing any boson like retarded mediation between them, and a quartet structure among paired four quasiparticles will be further formed, leading to the doubly lower biding energy than that from a single Cooper’s pair. Under a certain condition a superconducting phase transition, corresponding to the resonance of a many-electron system with repulsion in the spin singlet state, may occur naturally. This showcases the physical picture of our earlier assertion [3] that superconductivity takes place naturally due to the Coulombic repulsive interaction.

  13. Thermospin effects in superconducting heterostructures

    Science.gov (United States)

    Bobkova, I. V.; Bobkov, A. M.

    2017-09-01

    Recently, thermally created pure spin currents were predicted for Zeeman-split superconductor/normal-metal heterostructures. Here it is shown that this "thermospin" current can lead to an accumulation of a pure spin imbalance in a system. The thermally induced spin imbalance can reach the value of Zeeman splitting of the superconducting density of states and strongly influences superconductivity in the heterostructure. Depending on the temperature difference between the superconductor and the normal reservoir it can enhance the critical temperature of the superconductor or additionally suppress the zero-temperature superconducting state. The last possibility gives rise to an unusual superconducting state, which starts to develop at finite temperature.

  14. Superconducting Nonlinear Kinetic Inductance Devices

    Data.gov (United States)

    National Aeronautics and Space Administration — Superconducting quantum interference devices, or SQUIDs, are by far the most sensitive magnetometers available, but two issues limit their commercial potential:...

  15. Korea's developmental program for superconductivity

    Science.gov (United States)

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

    1995-04-01

    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.

  16. Unconventional superconductivity in honeycomb lattice

    Directory of Open Access Journals (Sweden)

    P Sahebsara

    2013-03-01

    Full Text Available   ‎ The possibility of symmetrical s-wave superconductivity in the honeycomb lattice is studied within a strongly correlated regime, using the Hubbard model. The superconducting order parameter is defined by introducing the Green function, which is obtained by calculating the density of the electrons ‎ . In this study showed that the superconducting order parameter appears in doping interval between 0 and 0.5, and x=0.25 is the optimum doping for the s-wave superconductivity in honeycomb lattice.

  17. Tuning the Superconducting Properties of Magnesium Diboride

    Energy Technology Data Exchange (ETDEWEB)

    Theoderich Wilke, Rudeger Heinrich [Iowa State Univ., Ames, IA (United States)

    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.

  18. Determination of copper oxidizing power in superconducting yttrium ceramics

    International Nuclear Information System (INIS)

    Pontaler, R.P.; Lebed', N.B.

    1989-01-01

    A new photometric method for determining the formal copper degree of oxidation and oxygen deficiency in superconducting high-temperature oxides containing yttrium, barium and copper is developed. The method is based on oxidation of Co(2) complex with EDTA by Cu(3) ions in acetrate buffer solution with pH 4.2-4.7 and allows one to determine 1-10% of Cu(3). Relative standard deviation when determining Cu(3) makes up 0.03-0.05. Using a qualitative reaction with the application of sodium vanadate hydrochloride solution the absence of peroxide compound in superconducting yttrium ceramics is ascertained

  19. Pseudogap and Superconducting Gap in Sm FeAs(O1-xFx) Superconductor from Photoemission Spectroscopy

    International Nuclear Information System (INIS)

    Hai-Yun, Liu; Xiao-Wen, Jia; Wen-Tao, Zhang; Lin, Zhao; Jian-Qiao, Meng; Guo-Dong, Liu; Xiao-Li, Dong; Zhi-An, Ren; Wei, Yi; Guang-Can, Che; Zhong-Xian, Zhao; Gang, Wu; Rong-Hua, Liu; Xian-Hui, Chen; Gen-Fu, Chen; Nan-Lin, Wang; Gui-Ling, Wang; Yong, Zhou; Yong, Zhu; Xiao-Yang, Wang

    2008-01-01

    High resolution photoemission measurements are carried out on non-superconducting SmOFeAs parent compound and superconducting SmFeAs(O 1-x F x ) (x = 0.12, and 0.15) compounds. The momentum-integrated spectra exhibit a clear Fermi cutoff that shows little leading-edge shift in the superconducting state. A robust feature at 13meV is identified in all these samples. Spectral weight suppression near Ef with decreasing temperature is observed in both undoped and doped samples that points to a possible existence of a pseudogap in these Fe-based compounds

  20. Superconductivity in the PbO-type structure alpha-FeSe.

    Science.gov (United States)

    Hsu, Fong-Chi; Luo, Jiu-Yong; Yeh, Kuo-Wei; Chen, Ta-Kun; Huang, Tzu-Wen; Wu, Phillip M; Lee, Yong-Chi; Huang, Yi-Lin; Chu, Yan-Yi; Yan, Der-Chung; Wu, Maw-Kuen

    2008-09-23

    The recent discovery of superconductivity with relatively high transition temperature (Tc) in the layered iron-based quaternary oxypnictides La[O(1-x)F(x)] FeAs by Kamihara et al. [Kamihara Y, Watanabe T, Hirano M, Hosono H (2008) Iron-based layered superconductor La[O1-xFx] FeAs (x = 0.05-0.12) with Tc = 26 K. J Am Chem Soc 130:3296-3297.] was a real surprise and has generated tremendous interest. Although superconductivity exists in alloy that contains the element Fe, LaOMPn (with M = Fe, Ni; and Pn = P and As) is the first system where Fe plays the key role to the occurrence of superconductivity. LaOMPn has a layered crystal structure with an Fe-based plane. It is quite natural to search whether there exists other Fe based planar compounds that exhibit superconductivity. Here, we report the observation of superconductivity with zero-resistance transition temperature at 8 K in the PbO-type alpha-FeSe compound. A key observation is that the clean superconducting phase exists only in those samples prepared with intentional Se deficiency. FeSe, compared with LaOFeAs, is less toxic and much easier to handle. What is truly striking is that this compound has the same, perhaps simpler, planar crystal sublattice as the layered oxypnictides. Therefore, this result provides an opportunity to better understand the underlying mechanism of superconductivity in this class of unconventional superconductors.

  1. Optimization of superconducting tiling pattern for superconducting bearings

    Energy Technology Data Exchange (ETDEWEB)

    Hull, John R. (Hinsdale, IL)

    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.

  2. Superconductivity in Co-doped SmFeAsO

    International Nuclear Information System (INIS)

    Qi Yanpeng; Gao Zhaoshun; Wang Lei; Wang Dongliang; Zhang Xianping; Ma Yanwei

    2008-01-01

    Here we report the synthesis and characterizations of SmFe 1-x Co x AsO (x = 0.10, 0.15) for the first time. The parent compound SmFeAsO itself is not superconducting but shows an antiferromagnetic order near 150 K, which must be suppressed by doping before superconductivity emerges. With Co doping in the FeAs planes, antiferromagnetic order is destroyed and superconductivity occurs at 15.2 K. Similar to LaFe 1-x Co x AsO, the SmFe 1-x Co x AsO system appears to tolerate considerable disorder in the FeAs planes. This result is important, suggesting a different mechanism for cuprate superconductors compared to the iron-based arsenide ones.

  3. Neutron scattering and the search for mechanisms of superconductivity

    DEFF Research Database (Denmark)

    Aeppli, G.; Bishop, D.J.; Broholm, C.

    1999-01-01

    Neutron scattering is a direct probe of mass and magnetization density in solids. We start with a brief review of experimental strategies for determining the mechanisms of superconductivity and how neutron scattering contributed towards our understanding of conventional superconductors. The remai......Neutron scattering is a direct probe of mass and magnetization density in solids. We start with a brief review of experimental strategies for determining the mechanisms of superconductivity and how neutron scattering contributed towards our understanding of conventional superconductors....... The remainder of the article gives examples of neutron results with impact on the search for the mechanism of superconductivity in more recently discovered, 'exotic', materials, namely the heavy fermion compounds and the layered cuprates, (C) 1999 Elsevier Science B.V. All rights reserved....

  4. Superconducting bearings for flywheel applications

    DEFF Research Database (Denmark)

    Abrahamsen, A.B.

    2001-01-01

    A literature study on the application of superconducting bearings in energy storage flywheel systems. The physics of magnetic levitation and superconductors are presented in the first part of the report, followed by a discussion of the literature found onthe applications of superconducting bearings...

  5. Defects and an unusual superconductivity

    Energy Technology Data Exchange (ETDEWEB)

    Gor' kov, L.P.; Kalugin, P.A.

    1985-03-10

    If the superconducting gap in a pure material has zeros on an entire line along the Fermi surface, the state density is finite at epsilon = 0, beginning with the lowest defect concentrations. The splitting of the superconducting transition by impurities, U/sub 1-x/Th/sub x/Be/sub 13/ is discussed.

  6. Heavy-ion superconducting linacs

    International Nuclear Information System (INIS)

    Delayen, J.R.

    1989-01-01

    This paper reviews the status of the superconducting heavy-ion accelerators. Most of them are linacs used as boosters for tandem electrostatic accelerators, although the technology is being extended to very low velocity to eliminate the need for an injector. The characteristics and features of the various superconducting heavy-ion accelerators are discussed. 45 refs

  7. The Danish Superconducting Cable Project

    DEFF Research Database (Denmark)

    Tønnesen, Ole

    1997-01-01

    The design and construction of a superconducting cable is described. The cable has a room temperature dielectric design with the cryostat placed inside the electrical insulation.BSCCO 2223 superconducting tapes wound in helix form around a former are used as the cable conductor. Results from...

  8. Superconductivity under high pressure

    Energy Technology Data Exchange (ETDEWEB)

    Amaya, K.; Shimizu, K.; Takeda, K.; Tateiwa, N.; Muramatsu, T.; Ishizuka, M.; Kobayashi, T.C

    2003-05-01

    In part 1, we review techniques developed in our laboratory for producing the complex extreme condition of very low temperature and ultra-high pressure and those for measuring electrical resistance and magnetization of the sample confined in the extremely small space of the used pressure cell. In part 2, we review our experimental results in search for pressure-induced superconductivity, which have been obtained by the use of developed techniques. Typical examples are shown in the case of simple inorganic and organic molecular crystals, ionic crystals, and magnetic metals.

  9. Introduction to superconductivity

    CERN Document Server

    Rose-Innes, A C

    1978-01-01

    Introduction to Superconductivity differs from the first edition chiefly in Chapter 11, which has been almost completely rewritten to give a more physically-based picture of the effects arising from the long-range coherence of the electron-waves in superconductors and the operation of quantum interference devices. In this revised second edition, some further modifications have been made to the text and an extra chapter dealing with """"high-temperature"""" superconductors has been added. A vast amount of research has been carried out on these since their discovery in 1986 but the results, both

  10. Remarks on superconductive networks

    International Nuclear Information System (INIS)

    Dominguez, D.; Lopez, A.R.N.; Simonin, J.M.

    1989-01-01

    Some remarks on the determination of the normal-superconductor phase boundary in random superconductive networks are made. A recently reported work by Soukoulis, Grest and Li which introduces weak links between nodes as these are removed in the site percolation problem is discussed. By the analysis of two simple geometries, it is shown that this procedure introduces spurious effects which mask the physical properties of the system. These affect in particular the field slope critical index and the sharpness of the normal-superconductor boundary. (Author)

  11. Superconductivity at disordered interfaces

    International Nuclear Information System (INIS)

    Simanek, E.

    1979-01-01

    The increase of the superconducting transition temperature Tsub(c) due to the tunneling of conduction electrons into negative-u centers at a disordered metal-semiconductor interface is calculated. The strong dependence of the experimental increase of Tsub(c) on the Fermi energy of the metal is accounted for by the polaronic reduction of the tunneling matrix elements. The latter reduction is dynamically suppressed by the decreasing lifetime of the localized state as Esub(F) increases. The theoretical enhancement is sufficiently strong to explain the increase of Tsub(c) observed in eutectic alloys. (author)

  12. Review of superconducting linacs

    International Nuclear Information System (INIS)

    Bollinger, L.M.

    1992-01-01

    This paper summarizes the status of the technology of superconducting (SC) linacs designed for the acceleration of ions. The emphasis is on the technical issues involved, with only brief descriptions of the numerous linacs now in operation or under construction. Recent developments of special interest are treated in more detail, and remaining technical challenges are outlined. The technology required for acceleration of ions with velocity β ∼ 1 is not discussed because it is almost the same as for relativistic electrons. That is, this paper is mainly about SC linacs for low-velocity heavy ions. (Author) 5 tabs., 6 figs., 29 refs

  13. Precursor of color superconductivity

    Energy Technology Data Exchange (ETDEWEB)

    Kitazawa, M. [Kyoto Univ., Dept. of Physics, Kyoto (Japan); Koide, T.; Kunihiro, T. [Kyoto Univ., Yukawa Institute for Theoretical Physics, Kyoto (Japan); Nemoto, Y. [Brookhaven National Laboratory, RIKEN BNL Research Center, Upton, NY (United States)

    2002-09-01

    We investigate possible precursory phenomena of color superconductivity in quark matter at finite temperature T with use of a simple Nambu-Jona-Lasinio model. It is found that the fluctuating pair field exists with a prominent strength even well above the critical temperature T{sub c}. We show that the collective pair field has a complex energy located in the second Riemann sheet, which approaches the origin as T is lowered to T{sub c}. We discuss the possible relevance of the precursor to the observables to be detected in heavy ion collisions. (author)

  14. Superconductivity in nanowires

    CERN Document Server

    Bezryadin, Alexey

    2012-01-01

    The importance and actuality of nanotechnology is unabated and will be for years to come. A main challenge is to understand the various properties of certain nanostructures, and how to generate structures with specific properties for use in actual applications in Electrical Engineering and Medicine.One of the most important structures are nanowires, in particular superconducting ones. They are highly promising for future electronics, transporting current without resistance and at scales of a few nanometers. To fabricate wires to certain defined standards however, is a major challenge, and so i

  15. Superconducting ac cable

    International Nuclear Information System (INIS)

    Schmidt, F.

    1980-01-01

    The components of a superconducting 110 kV ac cable for power ratings >= 2000 MVA have been developed. The cable design especially considered was of the semiflexible type, with a rigid cryogenic envelope and flexible hollow coaxial cable cores pulled into the former. The cable core consists of spirally wound Nb-Al composite wires and a HDPE-tape wrapped electrical insulation. A 35 m long single phase test cable with full load terminations for 110 kV and 10 kA was constructed and successfully tested. The results obtained prove the technical feasibility and capability of our cable design. (orig.) [de

  16. High gradient superconducting quadrupoles

    International Nuclear Information System (INIS)

    Lundy, R.A.; Brown, B.C.; Carson, J.A.; Fisk, H.E.; Hanft, R.H.; Mantsch, P.M.; McInturff, A.D.; Remsbottom, R.H.

    1987-07-01

    Prototype superconducting quadrupoles with a 5 cm aperture and gradient of 16 kG/cm have been built and tested as candidate magnets for the final focus at SLC. The magnets are made from NbTi Tevatron style cable with 10 inner and 14 outer turns per quadrant. Quench performance and multipole data are presented. Design and data for a low current, high gradient quadrupole, similar in cross section but wound with a cable consisting of five insulated conductors are also discussed

  17. Superconducting switch and amplifier device

    International Nuclear Information System (INIS)

    Faris, S.M.

    1982-01-01

    An amplifying or switching superconductive device is described whose current-voltage characteristic is drastically altered by heavy injection of excess energetic quasi-particles. In this device, the superconducting bandgap of a superconducting layer is greatly altered by overinjection of energetic quasi-particles so that the bandgap changes greatly with respect to its thermal equilibrium value, and in most cases is made to vanish. In a preferred embodiment, a three electrode device is fabricated where at least one of the electrodes is a superconductor. Tunnel barriers are located between the electrodes. A first tunnel junction is used to heavily inject energetic quasi-particles into the superconducting electrode to change its superconducting bandgap drastically. In turn, this greatly modifies the currentvoltage characteristics of the second tunnel junction. This device can be used to provide logic circuits, or as an amplifier, and has an output sufficiently large that it can drive other similar devices

  18. A new compound - Ta3Pb : manufacture, structure and properties

    International Nuclear Information System (INIS)

    Tuleushev, A.Zh.; Tuleushev, Yu.Zh.; Volodin, V.N.; Zhakanbaev, E.A.

    2003-01-01

    For the first time by the magnetron sputtering and tantalum deposition on substrates from molybdenum and tungsten the covers presenting the lead solution in cubic α-tantalum (up to 2.5 at % Pb) were obtained. The lead dissolution is accompanying by the Ta lattice parameter increasing from 0.3314 to 0.3321 nm in the lead concentration range from 0.2 to 2.5 at. % Pb. The cryogenic examinations of the synthesised covers conducted by four-probes electric resistance method show the absence the superconductivity up to the 4.2 K temperature. So, for the first time the Ta 2 Pb compound with A15 structure was synthesised and data for its identification were determined

  19. Topics in unconventional superconductivity

    Science.gov (United States)

    Oreto, Paul

    Disordered systems have been of continuing interest to condensed matter physicists. Disorder is associated with a wide range of interesting phenomena such as glassiness and localization. Superconductivity, the phase of matter in which materials conduct without dissipation, has similarly fascinated condensed matter physicists, as it is an outstanding example of the macroscopic effects of quantum mechanics. In this thesis, the interplay of superconductivity and disorder is discussed. The particular focus of this thesis is how a BCS d-wave superconductor in the quantum superconductor to metal transition can develop a global s-wave phase due to the existence of rare regions. The critical assumption of this work is that the metal is highly conducting. Though the calculations done in this thesis are all in the weak coupling framework, it is possible that this phase might be observed in the overdoped cuprates. Additionally, this thesis contains a discussion of the effect of critical nematic fluctuations on relativistic nodal quasiparticles. In this work, it is found that the nematic order increases the anisotropy in the velocity of the nodal quasiparticles and broadens the quasiparticle peaks except for a narrow wedge in momentum space near the Fermi surface where the quasiparticles remain sharp. The implications for the cuprates are discussed.

  20. Additive Manufactured Superconducting Cavities

    Science.gov (United States)

    Holland, Eric; Rosen, Yaniv; Woolleet, Nathan; Materise, Nicholas; Voisin, Thomas; Wang, Morris; Mireles, Jorge; Carosi, Gianpaolo; Dubois, Jonathan

    Superconducting radio frequency cavities provide an ultra-low dissipative environment, which has enabled fundamental investigations in quantum mechanics, materials properties, and the search for new particles in and beyond the standard model. However, resonator designs are constrained by limitations in conventional machining techniques. For example, current through a seam is a limiting factor in performance for many waveguide cavities. Development of highly reproducible methods for metallic parts through additive manufacturing, referred to colloquially as 3D printing\\x9D, opens the possibility for novel cavity designs which cannot be implemented through conventional methods. We present preliminary investigations of superconducting cavities made through a selective laser melting process, which compacts a granular powder via a high-power laser according to a digitally defined geometry. Initial work suggests that assuming a loss model and numerically optimizing a geometry to minimize dissipation results in modest improvements in device performance. Furthermore, a subset of titanium alloys, particularly, a titanium, aluminum, vanadium alloy (Ti - 6Al - 4V) exhibits properties indicative of a high kinetic inductance material. This work is supported by LDRD 16-SI-004.

  1. Superconductivity and future accelerators

    International Nuclear Information System (INIS)

    Danby, G.T.; Jackson, J.W.

    1963-01-01

    For 50 years particle accelerators employing accelerating cavities and deflecting magnets have been developed at a prodigious rate. New accelerator concepts and hardware ensembles have yielded great improvements in performance and GeV/$. The great idea for collective acceleration resulting from intense auxiliary charged-particle beams or laser light may or may not be just around the corner. In its absence, superconductivity (SC) applied both to rf cavities and to magnets opened up the potential for very large accelerators without excessive energy consumption and with other economies, even with the cw operation desirable for colliding beams. HEP has aggressively pioneered this new technology: the Fermilab single ring 1 TeV accelerator - 2 TeV collider is near the testing stage. Brookhaven National Laboratory's high luminosity pp 2 ring 800 GeV CBA collider is well into construction. Other types of superconducting projects are in the planning stage with much background R and D accomplished. The next generation of hadron colliders under discussion involves perhaps a 20 TeV ring (or rings) with 40 TeV CM energy. This is a very large machine: even if the highest practical field B approx. 10T is used, the radius is 10x that of the Fermilab accelerator. An extreme effort to get maximum GeV/$ may be crucial even for serious consideration of funding

  2. Superconducting magnetic energy storage

    International Nuclear Information System (INIS)

    Rogers, J.D.; Boenig, H.J.

    1978-01-01

    Superconducting inductors provide a compact and efficient means of storing electrical energy without an intermediate conversion process. Energy storage inductors are under development for diurnal load leveling and transmission line stabilization in electric utility systems and for driving magnetic confinement and plasma heating coils in fusion energy systems. Fluctuating electric power demands force the electric utility industry to have more installed generating capacity than the average load requires. Energy storage can increase the utilization of base-load fossil and nuclear power plants for electric utilities. Superconducting magnetic energy storage (SMES) systems, which will store and deliver electrical energy for load leveling, peak shaving, and the stabilization of electric utility networks are being developed. In the fusion area, inductive energy transfer and storage is also being developed by LASL. Both 1-ms fast-discharge theta-pinch and 1-to-2-s slow tokamak energy transfer systems have been demonstrated. The major components and the method of operation of an SMES unit are described, and potential applications of different size SMES systems in electric power grids are presented. Results are given for a 1-GWh reference design load-leveling unit, for a 30-MJ coil proposed stabilization unit, and for tests with a small-scale, 100-kJ magnetic energy storage system. The results of the fusion energy storage and transfer tests are also presented. The common technology base for the systems is discussed

  3. Overview on superconducting photoinjectors

    CERN Document Server

    Arnold, A

    2011-01-01

    The success of most of the proposed energy recovery linac (ERL) based electron accelerator projects for future storage ring replacements (SRR) and high power IR–free-electron lasers (FELs) largely depends on the development of an appropriate source. For example, to meet the FEL specifications [J.W. Lewellen, Proc. SPIE Int. Soc. Opt. Eng. 5534, 22 (2004)] electron beams with an unprecedented combination of high brightness, low emittance (0.1 µmrad), and high average current (hundreds of mA) are required. An elegant way to create a beam of such quality is to combine the high beam quality of a normal conducting rf photoinjector with the superconducting technology, i.e., to build a superconducting rf photoinjector (SRF gun). SRF gun R&D programs based on different approaches have been launched at a growing number of institutes and companies (AES, Beijing University, BESSY, BNL, DESY, FZD, TJNAF, Niowave, NPS, Wisconsin University). Substantial progress was achieved in recent years and the first long term ...

  4. Superconducting composites materials

    International Nuclear Information System (INIS)

    Kerjouan, P.; Boterel, F.; Lostec, J.; Bertot, J.P.; Haussonne, J.M.

    1991-01-01

    The new superconductor materials with a high critical current own a large importance as well in the electronic components or in the electrotechnical devices fields. The deposit of such materials with the thick films technology is to be more and more developed in the years to come. Therefore, we tried to realize such thick films screen printed on alumina, and composed mainly of the YBa 2 Cu 3 O 7-δ material. We first realized a composite material glass/YBa 2 Cu 3 O 7-δ , by analogy with the classical screen-printed inks where the glass ensures the bonding with the substrate. We thus realized different materials by using some different classes of glass. These materials owned a superconducting transition close to the one of the pure YBa 2 Cu 3 O 7-δ material. We made a slurry with the most significant composite materials and binders, and screen-printed them on an alumina substrate preliminary or not coated with a diffusion barrier layer. After firing, we studied the thick films adhesion, the alumina/glass/composite material interfaces, and their superconducting properties. 8 refs.; 14 figs.; 9 tabs [fr

  5. Electronic origin of high-temperature superconductivity in single-layer FeSe superconductor.

    Science.gov (United States)

    Liu, Defa; Zhang, Wenhao; Mou, Daixiang; He, Junfeng; Ou, Yun-Bo; Wang, Qing-Yan; Li, Zhi; Wang, Lili; Zhao, Lin; He, Shaolong; Peng, Yingying; Liu, Xu; Chen, Chaoyu; Yu, Li; Liu, Guodong; Dong, Xiaoli; Zhang, Jun; Chen, Chuangtian; Xu, Zuyan; Hu, Jiangping; Chen, Xi; Ma, Xucun; Xue, Qikun; Zhou, X J

    2012-07-03

    The recent discovery of high-temperature superconductivity in iron-based compounds has attracted much attention. How to further increase the superconducting transition temperature (T(c)) and how to understand the superconductivity mechanism are two prominent issues facing the current study of iron-based superconductors. The latest report of high-T(c) superconductivity in a single-layer FeSe is therefore both surprising and significant. Here we present investigations of the electronic structure and superconducting gap of the single-layer FeSe superconductor. Its Fermi surface is distinct from other iron-based superconductors, consisting only of electron-like pockets near the zone corner without indication of any Fermi surface around the zone centre. Nearly isotropic superconducting gap is observed in this strictly two-dimensional system. The temperature dependence of the superconducting gap gives a transition temperature T(c)~ 55 K. These results have established a clear case that such a simple electronic structure is compatible with high-T(c) superconductivity in iron-based superconductors.

  6. Magnetic Ordering In Superconducting Nb-doped Bi2Se3

    Science.gov (United States)

    Corbae, Paul; Lawson, Benjamin; Li, Gang; Yu, Fan; Asaba, Tomoya; Tinsman, Colin; Qui, Yusheng; Hor, Yew San; Li, Lu

    Coexistence of superconductivity and magnetic order has been suggested by early studies of topological superconductor candidate, niobium doped Bi2Se3. In order to elucidate the interesting physics of this coexistence, we performed highly sensitive torque magnetometry to study the material's magnetization. We observed a bump feature in the magnetization around 8 Tesla in both the superconducting and non-superconducting samples. This is distinct from the paramagnetic torque response of the parent compound, Bi2Se3, suggesting some interesting magnetic order in Nb-doped Bi2Se3.

  7. Operational Merits of Maritime Superconductivity

    Science.gov (United States)

    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

  8. 7 CFR 15a.15 - Exempt activities.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 1 2010-01-01 2010-01-01 false Exempt activities. 15a.15 Section 15a.15 Agriculture Office of the Secretary of Agriculture EDUCATION PROGRAMS OR ACTIVITIES RECEIVING OR BENEFITTING FROM FEDERAL FINANCIAL ASSISTANCE Coverage § 15a.15 Exempt activities. (a) These regulations shall not apply to...

  9. Charge density wave and superconductivity in 2H- and 4H-NbSe2 ...

    Indian Academy of Sciences (India)

    Transition metal compounds; superconductivity. PACS Nos 72.80.Ga; 74.25.Op. 1. Introduction. Group V transition metal dichalcogenide compounds (TMDC) with ... face nesting [3] or the saddle points in the electronic band [4]. .... are quite different between the parallel and perpendicular to the layer as expected in large.

  10. Signatures of topological superconductivity

    Energy Technology Data Exchange (ETDEWEB)

    Peng, Yang

    2017-07-19

    The prediction and experimental discovery of topological insulators brought the importance of topology in condensed matter physics into the limelight. Topology hence acts as a new dimension along which more and more new states of matter start to emerge. One of these topological states of matter, namely topological superconductors, comes into the focus because of their gapless excitations. These gapless excitations, especially in one dimensional topological superconductors, are Majorana zero modes localized at the ends of the superconductor and exhibit exotic nonabelian statistics, which can be potentially applied to fault-tolerant quantum computation. Given their highly interesting physical properties and potential applications to quantum computation, both theorists and experimentalists spend great efforts to realize topological supercondoctors and to detect Majoranas. In two projects within this thesis, we investigate the properties of Majorana zero modes in realistic materials which are absent in simple theoretical models. We find that the superconducting proximity effect, an essential ingredient in all existing platforms for topological superconductors, plays a significant role in determining the localization property of the Majoranas. Strong proximity coupling between the normal system and the superconducting substrate can lead to strongly localized Majoranas, which can explain the observation in a recent experiment. Motivated by experiments in Molenkamp's group, we also look at realistic quantum spin Hall Josephson junctions, in which charge puddles acting as magnetic impurities are coupled to the helical edge states. We find that with this setup, the junction generically realizes an exotic 8π periodic Josephson effect, which is absent in a pristine Josephson junction. In another two projects, we propose more pronounced signatures of Majoranas that are accessible with current experimental techniques. The first one is a transport measurement, which uses

  11. A15 Nb-Sn tunnel junction fabrication and properties

    International Nuclear Information System (INIS)

    Rudman, D.A.; Hellman, F.; Hammond, R.H.; Beasley, M.R.

    1984-01-01

    We have investigated the deposition conditions necessary to produce optimized films of A15 Nb-Sn (19--26 at. % Sn) by electron-beam codeposition. Reliable high-quality superconducting tunnel junctions can be made on this material by using an oxidized-amorphous silicon overlayer as the tunneling barrier and lead as the counter-electrode. These junctions have been used both as a tool for materials diagnosis and as a probe of the superconducting properties (critical temperature and gap) of the films. Careful control of the substrate temperature during the growth of the films has proved critical to obtain homogeneous samples. When the substrate temperature is properly stabilized, stoichiometric Nb 3 Sn is found to be relatively insensitive to the deposition temperature and conditions. In contrast, the properties of the off-stoichiometry (Sn-poor) material depend strongly on the deposition temperature. For this Sn-poor material the ratio 2Δ/kT/sub c/ at a given composition increases with increasing deposition temperature. This change appears to be due to an increase in the gap at the surface of the material (as measured by tunneling) relative to the critical temperature of the bulk. All the tunnel junctions exhibit some persistent nonidealities in their current-voltage characteristics that are qualitatively insensitive to composition or deposition conditions. In particular, the junctions show excess conduction below the sum of the energy gaps (with onset at the counter-electrode gap) and a broadened current rise at the sum gap. The detailed origins of these problems are not yet understood

  12. Superconducting Hadron Linacs

    CERN Document Server

    Ostroumov, Peter

    2013-01-01

    This article discusses the main building blocks of a superconducting (SC) linac, the choice of SC resonators, their frequencies, accelerating gradients and apertures, focusing structures, practical aspects of cryomodule design, and concepts to minimize the heat load into the cryogenic system. It starts with an overview of design concepts for all types of hadron linacs differentiated by duty cycle (pulsed or continuous wave) or by the type of ion species (protons, H-, and ions) being accelerated. Design concepts are detailed for SC linacs in application to both light ion (proton, deuteron) and heavy ion linacs. The physics design of SC linacs, including transverse and longitudinal lattice designs, matching between different accelerating–focusing lattices, and transition from NC to SC sections, is detailed. Design of high-intensity SC linacs for light ions, methods for the reduction of beam losses, preventing beam halo formation, and the effect of HOMs and errors on beam quality are discussed. Examples are ta...

  13. Superconducting coil protection

    International Nuclear Information System (INIS)

    Woods, E.L.

    1975-01-01

    The protection system is based on a two-phase construction program. Phase I is the development of a reliable hardwired relay control system with a digital loop utilizing firmware and a microprocessor controller. Phase II is an expansion of the digital loop to include many heretofore unmonitored coil variables. These new monitored variables will be utilized to establish early quench detection and to formulate confirmation techniques of the quench detection mechanism. Established quench detection methods are discussed and a new approach to quench detection is presented. The new circuit is insensitive to external pulsed magnetic fields and the associated induced voltages. Reliability aspects of the coil protection system are discussed with respect to shutdowns of superconducting coil systems. Redundance and digital system methods are presented as related topics

  14. The LHC superconducting cavities

    CERN Document Server

    Boussard, Daniel; Häbel, E; Kindermann, H P; Losito, R; Marque, S; Rödel, V; Stirbet, M

    1999-01-01

    The LHC RF system, which must handle high intensity (0.5 A d.c.) beams, makes use of superconducting single-cell cavities, best suited to minimizing the effects of periodic transient beam loading. There will be eight cavities per beam, each capable of delivering 2 MV (5 MV/m accelerating field) at 400 MHz. The cavities themselves are now being manufactured by industry, using niobium-on-copper technology which gives full satisfaction at LEP. A cavity unit includes a helium tank (4.5 K operating temperature) built around a cavity cell, RF and HOM couplers and a mechanical tuner, all housed in a modular cryostat. Four-unit modules are ultimately foreseen for the LHC (two per beam), while at present a prototype version with two complete units is being extensively tested. In addition to a detailed description of the cavity and its ancillary equipment, the first test results of the prototype will be reported.

  15. Superconducting pulsed magnets

    CERN Multimedia

    CERN. Geneva

    2006-01-01

    Lecture 1. Introduction to Superconducting Materials Type 1,2 and high temperature superconductors; their critical temperature, field & current density. Persistent screening currents and the critical state model. Lecture 2. Magnetization and AC Loss How screening currents cause irreversible magnetization and hysteresis loops. Field errors caused by screening currents. Flux jumping. The general formulation of ac loss in terms of magnetization. AC losses caused by screening currents. Lecture 3. Twisted Wires and Cables Filamentary composite wires and the losses caused by coupling currents between filaments, the need for twisting. Why we need cables and how the coupling currents in cables contribute more ac loss. Field errors caused by coupling currents. Lecture 4. AC Losses in Magnets, Cooling and Measurement Summary of all loss mechanisms and calculation of total losses in the magnet. The need for cooling to minimize temperature rise in a magnet. Measuring ac losses in wires and in magnets. Lecture 5. Stab...

  16. Brittle superconducting magnets: an equivilent strain model

    International Nuclear Information System (INIS)

    Barzi, E.; Danuso, M.

    2010-01-01

    To exceed fields of 10 T in accelerator magnets, brittle superconductors like A15 Nb 3 Sn and Nb 3 Al or ceramic High Temperature Superconductors have to be used. For such brittle superconductors it is not their maximum tensile yield stress that limits their structural resistance as much as strain values that provoke deformations in their delicate lattice, which in turn affect their superconducting properties. Work on the sensitivity of Nb 3 Sn cables to strain has been conducted in a number of stress states, including uniaxial and multi-axial, producing usually different results. This has made the need of a constituent design criterion imperative for magnet builders. In conventional structural problems an equivalent stress model is typically used to verify mechanical soundness. In the superconducting community a simple scalar equivalent strain to be used in place of an equivalent stress would be an extremely useful tool. As is well known in fundamental mechanics, there is not one single way to reduce a multiaxial strain state as represented by a 2nd order tensor to a scalar. The conceptual experiment proposed here will help determine the best scalar representation to use in the identification of an equivalent strain model.

  17. Self-similarity in applied superconductivity

    International Nuclear Information System (INIS)

    Dresner, Lawrence

    1981-09-01

    Self-similarity is a descriptive term applying to a family of curves. It means that the family is invariant to a one-parameter group of affine (stretching) transformations. The property of self-similarity has been exploited in a wide variety of problems in applied superconductivity, namely, (i) transient distribution of the current among the filaments of a superconductor during charge-up, (ii) steady distribution of current among the filaments of a superconductor near the current leads, (iii) transient heat transfer in superfluid helium, (iv) transient diffusion in cylindrical geometry (important in studying the growth rate of the reacted layer in A15 materials), (v) thermal expulsion of helium from quenching cable-in-conduit conductors, (vi) eddy current heating of irregular plates by slow, ramped fields, and (vii) the specific heat of type-II superconductors. Most, but not all, of the applications involve differential equations, both ordinary and partial. The novel methods explained in this report should prove of great value in other fields, just as they already have done in applied superconductivity. (author)

  18. Brittle superconducting magnets: an equivilent strain model

    Energy Technology Data Exchange (ETDEWEB)

    Barzi, E.; /Fermilab; Danuso, M.

    2010-08-01

    To exceed fields of 10 T in accelerator magnets, brittle superconductors like A15 Nb{sub 3}Sn and Nb{sub 3}Al or ceramic High Temperature Superconductors have to be used. For such brittle superconductors it is not their maximum tensile yield stress that limits their structural resistance as much as strain values that provoke deformations in their delicate lattice, which in turn affect their superconducting properties. Work on the sensitivity of Nb{sub 3}Sn cables to strain has been conducted in a number of stress states, including uniaxial and multi-axial, producing usually different results. This has made the need of a constituent design criterion imperative for magnet builders. In conventional structural problems an equivalent stress model is typically used to verify mechanical soundness. In the superconducting community a simple scalar equivalent strain to be used in place of an equivalent stress would be an extremely useful tool. As is well known in fundamental mechanics, there is not one single way to reduce a multiaxial strain state as represented by a 2nd order tensor to a scalar. The conceptual experiment proposed here will help determine the best scalar representation to use in the identification of an equivalent strain model.

  19. Overview on superconducting photoinjectors

    Directory of Open Access Journals (Sweden)

    A. Arnold

    2011-02-01

    Full Text Available The success of most of the proposed energy recovery linac (ERL based electron accelerator projects for future storage ring replacements (SRR and high power IR–free-electron lasers (FELs largely depends on the development of an appropriate source. For example, to meet the FEL specifications [J. W. Lewellen, Proc. SPIE Int. Soc. Opt. Eng. 5534, 22 (2004PSISDG0277-786X10.1117/12.557378] electron beams with an unprecedented combination of high brightness, low emittance (0.1  μmrad, and high average current (hundreds of mA are required. An elegant way to create a beam of such quality is to combine the high beam quality of a normal conducting rf photoinjector with the superconducting technology, i.e., to build a superconducting rf photoinjector (SRF gun. SRF gun R&D programs based on different approaches have been launched at a growing number of institutes and companies (AES, Beijing University, BESSY, BNL, DESY, FZD, TJNAF, Niowave, NPS, Wisconsin University. Substantial progress was achieved in recent years and the first long term operation was demonstrated at FZD [R. Xiang et al., in Proceedings of the 31st International Free Electron Laser Conference (FEL 09, Liverpool, UK (STFC Daresbury Laboratory, Warrington, 2009, p. 488]. In the near future SRF guns are expected to play an important role for linac-driven FEL facilities. In this paper we will review the concepts, the design parameters, and the status of the major SRF gun projects.

  20. MgB2 superconducting wires basics and applications

    CERN Document Server

    2016-01-01

    The compendium gives a complete overview of the properties of MgB2 (Magnesium Diboride), a superconducting compound with a transition temperature of Tc = 39K, from the fundamental properties to the fabrication of multifilamentary wires and to the presentation of various applications. Written by eminent researchers in the field, this indispensable volume not only discusses superconducting properties of MgB2 compounds, but also describes known preparation methods of thin films and of bulk samples obtained under high pressure methods. A unique selling point of the book is the detailed coverage of various applications based on MgB2, starting with MRI magnets and high current cables, cooled by Helium (He) vapor. High current cables cooled by liquid hydrogen are also highlighted as an interesting alternative due to the shrinking He reserves on earth. Other pertinent subjects comprise permanent magnets, ultrafine wires for space applications and wind generator projects.

  1. Mixed-mu superconducting bearings

    Science.gov (United States)

    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.

  2. The central question in superconductivity

    Science.gov (United States)

    Hirsch, J. E.

    I will argue that the most basic and fundamental question in superconductivity is: when a superconductor in a magnetic field goes normal, how does the supercurrent stop? The supercurrent has to stop before the material becomes resistive because the transition is reversible in an ideal situation, with no Joule heat dissipated. I will argue that the conventional BCS-London theory of superconductivity cannot answer this question. I will propose an answer to this question that requires that there is flow and counterflow of charge across the normal-superconductor phase boundary, and requires that the normal state current carriers have hole-like character. The conventional BCS-London theory of superconductivity does not have these physical elements, the theory of hole superconductivity does.

  3. Superconductivity in all its states

    CERN Multimedia

    Globe Info

    2011-01-01

    Temporary exhibition at the Saint-Genis-Pouilly Tourist Office. For the 100th anniversary of its discovery, take a plunge into the amazing world of superconductivity. Some materials, when cooled down to extreme temperatures, acquire a remarkable property -  they become superconducting. Superconductivity is a rare example of a quantum effect that can be witnessed on the macroscopic scale and is today at the heart of much research. In laboratories, researchers try to gain a better understanding of its origins, study new superconducting materials, explore the phenomenon at the nanometric scale and pursue their indefatigable search for new applications. Monday to Friday: 09:00 a.m. to 12:00 and 2:30 p.m. to 6:30 p.m. Saturday: 10:00 a.m. to 12:00 noon » Open to all – Admission free For further information: +33 (0)4 50 42 29 37

  4. Recent advances in fullerene superconductivity

    CERN Document Server

    Margadonna, S

    2002-01-01

    Superconducting transition temperatures in bulk chemically intercalated fulleride salts reach 33 K at ambient pressure and in hole-doped C sub 6 sub 0 derivatives in field-effect-transistor (FET) configurations, they reach 117 K. These advances pose important challenges for our understanding of high-temperature superconductivity in these highly correlated organic metals. Here we review the structures and properties of intercalated fullerides, paying particular attention to the correlation between superconductivity and interfullerene separation, orientational order/disorder, valence state, orbital degeneracy, low-symmetry distortions, and metal-C sub 6 sub 0 interactions. The metal-insulator transition at large interfullerene separations is discussed in detail. An overview is also given of the exploding field of gate-induced superconductivity of fullerenes in FET electronic devices.

  5. Superconducting materials and fabrication process

    International Nuclear Information System (INIS)

    Lafon, M.O.; Magnier, C.

    1989-01-01

    A fine powder of superconducting material is obtained from an aqueous solution of rare earth, alkaline earth metal and transition metal nitrates and/or acetates which is dried by atomization, calcined and eventually crushed [fr

  6. Advanced Superconducting Test Accelerator (ASTA)

    Data.gov (United States)

    Federal Laboratory Consortium — The Advanced Superconducting Test Accelerator (ASTA) facility will be based on upgrades to the existing NML pulsed SRF facility. ASTA is envisioned to contain 3 to 6...

  7. Positron annihilation in superconductive metals

    Energy Technology Data Exchange (ETDEWEB)

    Dekhtjar, I.J.

    1969-03-10

    A correlation is shown between the parameters of superconductive metals and those of positron annihilation. Particular attention is paid to the density states obtained from the electron specific heat.

  8. Superconductivity in Layered Organic Metals

    Directory of Open Access Journals (Sweden)

    Jochen Wosnitza

    2012-04-01

    Full Text Available In this short review, I will give an overview on the current understanding of the superconductivity in quasi-two-dimensional organic metals. Thereby, I will focus on charge-transfer salts based on bis(ethylenedithiotetrathiafulvalene (BEDT-TTF or ET for short. In these materials, strong electronic correlations are clearly evident, resulting in unique phase diagrams. The layered crystallographic structure leads to highly anisotropic electronic as well as superconducting properties. The corresponding very high orbital critical field for in-plane magnetic-field alignment allows for the occurrence of the Fulde–Ferrell– Larkin–Ovchinnikov state as evidenced by thermodynamic measurements. The experimental picture on the nature of the superconducting state is still controversial with evidence both for unconventional as well as for BCS-like superconductivity.

  9. Superconducting linacs used with tandems

    International Nuclear Information System (INIS)

    Ben-Zvi, I.

    1984-01-01

    The main features of superconducting linacs used as post-accelerators of tandems are reviewed. Various aspects of resonators, cryogenics and electronics are discussed, and recent advances in the field are presented. (orig.)

  10. The superconducting bending magnets 'CESAR'

    CERN Document Server

    Pérot, J

    1978-01-01

    In 1975, CERN decided to build two high precision superconducting dipoles for a beam line in the SPS north experimental area. The aim was to determine whether superconducting magnets of the required accuracy and reliability can be built and what their economies and performances in operation will be. Collaboration between CERN and CAE /SACLAY was established in order to make use of the knowledge and experience already acquired in the two laboratories. (0 refs).

  11. Transient stability of superconducting alternators

    International Nuclear Information System (INIS)

    Furuyama, M.; Kirtley, J.L. Jr.

    1975-01-01

    A simulation study is performed for the purpose of determining the transient stability characteristics of superconducting alternators. This simulation is compared with an equal area criterion method. It is found that superconducting machines have good transient stability characteristics, that field forcing is not particularly helpful nor necessary. It is also found that the equal area criterion is useful for computing critical clearing times, if voltage behind subtransient reactance is held constant. (U.S.)

  12. Superconducting Qubit Optical Transducer (SQOT)

    Science.gov (United States)

    2015-08-05

    has photon loss in the optical fibre would appear has an effective T1 process and destroy any entanglement. 2.2.3 TEMPORAL MODE FILTER FUNCTION To...SECURITY CLASSIFICATION OF: The SQOT (Superconducting Qubit Optical Transducer) project proposes to build a novel electro- optic system which can...exchange quantum information between optical qubits at telecom frequencies and superconducting qubits. A direct quantum information transfer between

  13. Composite conductor containing superconductive wires

    Energy Technology Data Exchange (ETDEWEB)

    Larson, W.L.; Wong, J.

    1974-03-26

    A superconductor cable substitute made by coworking multiple rods of superconductive niobium--titanium or niobium--zirconium alloy with a common copper matrix to extend the copper and rods to form a final elongated product which has superconductive wires distributed in a reduced cross-section copper conductor with a complete metallurgical bond between the normal-conductive copper and the superconductor wires contained therein is described. The superconductor cable can be in the form of a tube.

  14. Superconductivity in domains with corners

    DEFF Research Database (Denmark)

    Bonnaillie-Noel, Virginie; Fournais, Søren

    2007-01-01

    We study the two-dimensional Ginzburg-Landau functional in a domain with corners for exterior magnetic field strengths near the critical field where the transition from the superconducting to the normal state occurs. We discuss and clarify the definition of this field and obtain a complete...... asymptotic expansion for it in the large $\\kappa$ regime. Furthermore, we discuss nucleation of superconductivity at the boundary....

  15. Conceptual design report: superconducting booster

    International Nuclear Information System (INIS)

    1983-01-01

    The Superconducting Booster project includes the construction of a new high-voltage injector and buncher for the existing tandem, a magnetic transport system, an rf linac with superconducting resonators, and a rebuncher-debuncher. The booster will fit in existing space so that a new building is not required. The layout of the accelerator is given in Fig. I-1. The University of Washington is contributing approximately $1 M to this project

  16. Non-resonant microwave absorption studies of superconducting ...

    Indian Academy of Sciences (India)

    PACS Nos 74.60Ec; 74.60Ge; 74.60Jg; 74.60Ad; 74.90+n. The discovery [1] of superconductivity in the 'off the shelf' intermetallic compound MgB2 has given rise to a flurry of ... have been the subject of some controversy. For example, the observation [2] of boron isotope effect implies MgB2 to be a phonon mediated BCS ...

  17. Superconducting lead particles produced by chemical techniques

    Science.gov (United States)

    Fariss, T. L.; Nixon, W. E.; Bucelot, T. J.; Deaver, B. S., Jr.; Mitchell, J. W.

    1982-09-01

    The superconductivity of extremely small lead particles has been studied as a function of size, surface condition, and connectivity using chemical techniques to produce particles of well-controlled size and shape suspended in insulating media. Approximately monodisperse suspensions of equiaxed, rod, and lath-shaped particles of lead halides and other lead compounds suspended in gelatin, polyacrylamide, polyvinylpyrrolidone, polyvinyl alcohol, methyl cellulose, and hydroxyethyl cellulose have been produced. These particles have been reduced to pseudomorphs of lead in the liquid phase or the suspensions have been coated on substrates and dried before reduction. Reducing solutions containing aminoiminomethanesulfinic acid are effective with particles of lead halides, lead phosphate, lead sulfate, and lead tartrate. Suspensions of smaller discrete lead particles have also been produced by direct reduction of solutions of soluble lead salts containing suitable polymers, chelating, and stabilizing agents. Dispersions with mean particle dimensions between 3 nm and 5 μm, and a narrow size-frequency distribution, have been produced. The superconductivity of the particles has been characterized by measurements of the magnetization as a function of temperature and magnetic field. The larger particles have a transition temperature of 7.2 K, the same as bulk lead; however, for particles of characteristic dimensions less than 20 nm, the transition temperature is lower by ˜0.1 K.

  18. Superconducting lead particles produced by chemical techniques

    International Nuclear Information System (INIS)

    Fariss, T.L.; Nixon, W.E.; Bucelot, T.J.; Deaver, B.S. Jr.; Mitchell, J.W.

    1982-01-01

    The superconductivity of extremely small lead particles has been studied as a function of size, surface condition, and connectivity using chemical techniques to produce particles of well-controlled size and shape suspended in insulating media. Approximately monodisperse suspensions of equiaxed, rod, and lath-shaped particles of lead halides and other lead compounds suspended in gelatin, polyacrylamide, polyvinylpyrrolidone, polyvinyl alcohol, methyl cellulose, and hydroxyethyl cellulose have been produced. These particles have been reduced to pseudomorphs of lead in the liquid phase or the suspensions have been coated on substrates and dried before reduction. Reducing solutions containing aminoiminomethanesulfinic acid are effective with particles of lead halides, lead phosphate, lead sulfate, and lead tartrate. Suspensions of smaller discrete lead particles have also been produced by direct reduction of solutions of soluble lead salts containing suitable polymers, chelating, and stabilizing agents. Dispersions with mean particle dimensions between 3 nm and 5 μm, and a narrow size-frequency distribution, have been produced. The superconductivity of the particles has been characterized by measurements of the magnetization as a function of temperature and magnetic field. The larger particles have a transition temperature of 7.2 K, the same as bulk lead; however, for particles of characteristic dimensions less than 20 nm, the transition temperature is lower by approx.0.1 K

  19. High-temperature superconducting conductors and cables

    International Nuclear Information System (INIS)

    Peterson, D.E.; Maley, M.P.; Boulaevskii, L.; Willis, J.O.; Coulter, J.Y.; Ullmann, J.L.; Cho, Jin; Fleshler, S.

    1996-01-01

    This is the final report of a 3-year LDRD project at LANL. High-temperature superconductivity (HTS) promises more efficient and powerful electrical devices such as motors, generators, and power transmission cables; however this depends on developing HTS conductors that sustain high current densities J c in high magnetic fields at temperatures near liq. N2's bp. Our early work concentrated on Cu oxides but at present, long wire and tape conductors can be best made from BSCCO compounds with high J c at low temperatures, but which are degraded severely at temperatures of interest. This problem is associated with thermally activated motion of magnetic flux lines in BSCCO. Reducing these dc losses at higher temperatures will require a high density of microscopic defects that will pin flux lines and inhibit their motion. Recently it was shown that optimum defects can be produced by small tracks formed by passage of energetic heavy ions. Such defects result when Bi is bombarded with high energy protons. The longer range of protons in matter suggests the possibility of application to tape conductors. AC losses are a major limitation in many applications of superconductivity such as power transmission. The improved pinning of flux lines reduces ac losses, but optimization also involves other factors. Measuring and characterizing these losses with respect to material parameters and conductor design is essential to successful development of ac devices

  20. A review of the properties of Nb3Sn and their variation with A15 composition, morphology and strain state

    International Nuclear Information System (INIS)

    Godeke, A

    2006-01-01

    Significant efforts can be found throughout the literature to optimize the current-carrying capacity of Nb 3 Sn superconducting wires. The achievable transport current density in wires depends on the A15 composition, morphology and strain state. The A15 sections in wires contain, due to compositional inhomogeneities resulting from solid-state diffusion A15 formation reactions, a distribution of superconducting properties. The A15 grain size can be different from wire to wire, and is also not necessarily homogeneous across the A15 regions. Strain is always present in composite wires, and the strain state changes as a result of thermal contraction differences and Lorentz forces in magnet systems. To optimize the transport properties, it is thus required to identify how composition, grain size and strain state influence the superconducting properties. This is not possible accurately in inhomogeneous and spatially complex systems such as wires. This article therefore gives an overview of the available literature on simplified, well-defined (quasi-)homogeneous laboratory samples. After more than 50 years of research on superconductivity in Nb 3 Sn, a significant amount of results are available, but these are scattered over a multitude of publications. Two reviews exist on the basic properties of A15 materials in general, but no specific review for Nb 3 Sn is available. This article is intended to provide such an overview. It starts with a basic description of the niobium-tin intermetallic. After that, it maps the influence of Sn content on the electron-phonon interaction strength and on the field-temperature phase boundary. The literature on the influence of Cu, Ti and Ta additions will then be summarized briefly. This is followed by a review of the effects of grain size and strain. The article concludes with a summary of the main results. (topical review)

  1. A search for superconductivity below 1 K in transition metal borides

    International Nuclear Information System (INIS)

    Leyarovska, L.; Leyarovski, E.

    1979-01-01

    Some AlB 2 -type (C32 structure) boron compounds were examined for superconductivity down to 0.42 K; the compounds have the formula MeB 2 (Me equivalent to Ti, Zr, Hf, V, Nb, Ta, Cr, Mo) (the atomic ratio of metal to boron was 0.5). Only NbB 2 was found to be superconducting with Tsub(c) = 0.62 K and a surprisingly high value of Hsub(c)(0), about 1600 Oe. Other transition metal as well as non-transition metal boron phases were also tested for superconductivity down to 0.42 K; these compounds were MeB 2 (Me equivalent to Ca, Sr, Ba), W 2 B 5 , CrB, Cr 5 B 3 , UB 2 , UB 4 and UB 12 . None of these compounds proved to be superconducting above 0.42 K; nor was any trace of superconductivity down to 0.42 K observed in MoB and NbB. (Auth.)

  2. Improved superconducting magnet wire

    Science.gov (United States)

    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.

  3. Superconducting digital logic amplifier

    International Nuclear Information System (INIS)

    Przybysz, J.X.

    1989-01-01

    This paper describes a superconducting digital logic amplifier for interfacing between a Josephson junction logic circuit having output current and a higher voltage semiconductor circuit input. The amplifier comprising: an input terminal for connection to a; an output terminal for connection to a semiconductor circuit input; an input, lower critical current, Josephson junction having first and second terminals; a first series string of at least three lower critical current Josephson junctions. The first series string being connected to the first terminal of the input Josephson junction such that the first series string is in series with the input Josephson junction to provide a series combination. The input terminal being connected to the first terminal of the input Josephson junction, and with the critical current of the lower critical current Josephson junctions of the input Josephson junction and the first series Josephson junctions being less than the output current of the low voltage Josephson junction circuit; a second series string of at least four higher critical current Josephson junctions. The second string being connected in parallel with the series combination to provide parallel strings having an upper common connection and a lower common connection. The lower common connection being connected to the second terminal of the input Josephson junction and the upper common connection being connected to the output terminal; and a pulsed DC current source connected the parallel strings at the upper common connection. The DC current source having a current at least equal to the critical current of the higher critical current Josephson junctions

  4. Superconducting magnet safety

    International Nuclear Information System (INIS)

    Arendt, F.; Komarek, P.

    1983-01-01

    One of the major components in a fusion reactor for which a safety analysis must be carried out is the magnet system. Most of the possible disturbances influencing the operation of superconducting magnets lead only to a quench, defined as an ''abnormal operating condition'' which causes just a temporary shut down of the magnet system without damage, if the system is well designed. More unlikely are accidental events which are associated with the generation of high power arcs. In these cases, single current arcs, e.g. at broken current leads, will lead to moderate damage only, but with the necessity of a longer shut down period for repair or replacing. Severe damage can only occur if in a multiple current arcing, starting by broken conductors, a wide-spread rupture of the winding occurs and the final high power arc burns through the coil case damaging other coils and reactor components. In a very hypothetical event the simultaneous rupture of the complete winding at two locations at least 1 m apart leads to missile generation due to the electromagnetic forces in the background field. The kinetic energy which the flying piece can get will be less than the values assumed for airplane crashes with the containment of modern fission power plants. (author)

  5. SNS superconducting linac

    International Nuclear Information System (INIS)

    Sundelin, Ronald M.

    2001-01-01

    The Spallation Neutron Source (SNS) decided in early 2000 to use superconducting RF (SRF) in the linac at energies above 185 MeV. Since the SNS duty cycle is 6%, the SRF and normal conducting approaches have capital costs which are about the same, but operating costs and future upgradability are improved by using SRF. The current status of cavity and cryomodule development and procurement, including the basis for decisions made, is discussed. The current plan includes use of 805 MHz, 6-cell cavities with geometrical betas of 0.61 and 0.81. There are 33 medium beta and 60 high beta cavities in 11 and 15 cryomodules, respectively. Each cavity (except the 93rd) is powered by a 550 kW pulsed klystron. Issues addressed include choice of peak surface gradient, optimization of cavity shape, selection of a scaled KEK input power coupler, selection of scaled TESLA higher mode couplers, and control of the effects of higher order modes on the beam. (author)

  6. Superconducting circuit fabrication

    International Nuclear Information System (INIS)

    Stein, B.F.; Young, P.L.

    1984-01-01

    An improved method of anodization of thin films for the fabrication of superconducting devices. An electrically conducting contact layer is formed over a substrate between an electrically conducting object layer and the substrate. Also, an electrically insulating layer is formed between the object layer and the contact layer. The contact layer is connected to a power supply and at least a preselected portion of the object layer is anodized to a predetermined thickness. This may include anodizing all of some preselected portions through the complete thickness of the object layer. A pattern of hardened photoresist on the object layer provides portions not protected by the pattern. When anodization of the electrically conducting object layer takes place, the resulting anodized portion is thicker than the thickness of the portion of the object layer that it replaces. The present invention further includes reducing the preselected portion of the object layer to be anodized by a predetermined amount before anodizing so that when anodization is complete, the resulting partially anodized partially conducting object layer is substantially planar. Alternatively, the thickness of the anodized preselected portions can be reduced after anodizing by a predetermined amount to cause the layer to be substantially planar. The same pattern of hardened photoresist can be used when reducing the thickness of portions of the object layer or anodized preselected portions

  7. The Superconducting TESLA Cavities

    CERN Document Server

    Aune, B.; Bloess, D.; Bonin, B.; Bosotti, A.; Champion, M.; Crawford, C.; Deppe, G.; Dwersteg, B.; Edwards, D.A.; Edwards, H.T.; Ferrario, M.; Fouaidy, M.; Gall, P-D.; Gamp, A.; Gössel, A.; Graber, J.; Hubert, D.; Hüning, M.; Juillard, M.; Junquera, T.; Kaiser, H.; Kreps, G.; Kuchnir, M.; Lange, R.; Leenen, M.; Liepe, M.; Lilje, L.; Matheisen, A.; Möller, W-D.; Mosnier, A.; Padamsee, H.; Pagani, C.; Pekeler, M.; Peters, H-B.; Peters, O.; Proch, D.; Rehlich, K.; Reschke, D.; Safa, H.; Schilcher, T.; Schmüser, P.; Sekutowicz, J.; Simrock, S.; Singer, W.; Tigner, M.; Trines, D.; Twarowski, K.; Weichert, G.; Weisend, J.; Wojtkiewicz, J.; Wolff, S.; Zapfe, K.

    2000-01-01

    The conceptional design of the proposed linear electron-positron colliderTESLA is based on 9-cell 1.3 GHz superconducting niobium cavities with anaccelerating gradient of Eacc >= 25 MV/m at a quality factor Q0 > 5E+9. Thedesign goal for the cavities of the TESLA Test Facility (TTF) linac was set tothe more moderate value of Eacc >= 15 MV/m. In a first series of 27industrially produced TTF cavities the average gradient at Q0 = 5E+9 wasmeasured to be 20.1 +- 6.2 MV/m, excluding a few cavities suffering fromserious fabrication or material defects. In the second production of 24 TTFcavities additional quality control measures were introduced, in particular aneddy-current scan to eliminate niobium sheets with foreign material inclusionsand stringent prescriptions for carrying out the electron-beam welds. Theaverage gradient of these cavities at Q0 = 5E+9 amounts to 25.0 +- 3.2 MV/mwith the exception of one cavity suffering from a weld defect. Hence only amoderate improvement in production and preparation technique...

  8. Qubit lattice coherence induced by electromagnetic pulses in superconducting metamaterials.

    Science.gov (United States)

    Ivić, Z; Lazarides, N; Tsironis, G P

    2016-07-12

    Quantum bits (qubits) are at the heart of quantum information processing schemes. Currently, solid-state qubits, and in particular the superconducting ones, seem to satisfy the requirements for being the building blocks of viable quantum computers, since they exhibit relatively long coherence times, extremely low dissipation, and scalability. The possibility of achieving quantum coherence in macroscopic circuits comprising Josephson junctions, envisioned by Legett in the 1980's, was demonstrated for the first time in a charge qubit; since then, the exploitation of macroscopic quantum effects in low-capacitance Josephson junction circuits allowed for the realization of several kinds of superconducting qubits. Furthermore, coupling between qubits has been successfully achieved that was followed by the construction of multiple-qubit logic gates and the implementation of several algorithms. Here it is demonstrated that induced qubit lattice coherence as well as two remarkable quantum coherent optical phenomena, i.e., self-induced transparency and Dicke-type superradiance, may occur during light-pulse propagation in quantum metamaterials comprising superconducting charge qubits. The generated qubit lattice pulse forms a compound "quantum breather" that propagates in synchrony with the electromagnetic pulse. The experimental confirmation of such effects in superconducting quantum metamaterials may open a new pathway to potentially powerful quantum computing.

  9. Superconductivity from magnetic elements under high pressure

    Energy Technology Data Exchange (ETDEWEB)

    Shimizu, Katsuya [KYOKUGEN, Research Center for Materials Science at Extreme Conditions, Osaka University, Osaka 560-8531 (Japan)]. E-mail: shimizu@rcem.osaka-u.ac.jp; Amaya, Kiichi [Toyota Physical and Chemical Research Institute, Aichi 480-1192 (Japan); Suzuki, Naoshi [Graduate School of Engineering Science, Osaka University, Osaka 560-8531 (Japan); Onuki, Yoshichika [Graduate School of Science, Osaka University, Osaka 560-0043 (Japan)

    2006-05-01

    Can we expect the appearance of superconductivity from magnetic elements? In general, superconductivity occurs in nonmagnetic metal at low temperature and magnetic impurities destroy superconductivity; magnetism and superconductivity are as incompatible as oil and water. Here, we present our experimental example of superconducting elements, iron and oxygen. They are magnetic at ambient pressure, however, they become nonmagnetic under high pressure, then superconductor at low temperature. What is the driving force of the superconductivity? Our understanding in the early stages was a simple scenario that the superconductive state was obtained as a consequence of an emergence of the nonmagnetic states. In both cases, we may consider another scenario for the appearance of superconductivity; the magnetic fluctuation mechanism in the same way as unconventional superconductors.

  10. Superconductivity from magnetic elements under high pressure

    International Nuclear Information System (INIS)

    Shimizu, Katsuya; Amaya, Kiichi; Suzuki, Naoshi; Onuki, Yoshichika

    2006-01-01

    Can we expect the appearance of superconductivity from magnetic elements? In general, superconductivity occurs in nonmagnetic metal at low temperature and magnetic impurities destroy superconductivity; magnetism and superconductivity are as incompatible as oil and water. Here, we present our experimental example of superconducting elements, iron and oxygen. They are magnetic at ambient pressure, however, they become nonmagnetic under high pressure, then superconductor at low temperature. What is the driving force of the superconductivity? Our understanding in the early stages was a simple scenario that the superconductive state was obtained as a consequence of an emergence of the nonmagnetic states. In both cases, we may consider another scenario for the appearance of superconductivity; the magnetic fluctuation mechanism in the same way as unconventional superconductors

  11. Superconductivity basics and applications to magnets

    CERN Document Server

    Sharma, R G

    2015-01-01

    This book presents the basics and applications of superconducting magnets. It explains the phenomenon of superconductivity, theories of superconductivity, type II superconductors and high-temperature cuprate superconductors. The main focus of the book is on the application to superconducting magnets to accelerators and fusion reactors and other applications of superconducting magnets. The thermal and electromagnetic stability criteria of the conductors and the present status of the fabrication techniques for future magnet applications are addressed. The book is based on the long experience of the author in studying superconducting materials, building magnets and numerous lectures delivered to scholars. A researcher and graduate student will enjoy reading the book to learn various aspects of magnet applications of superconductivity. The book provides the knowledge in the field of applied superconductivity in a comprehensive way.

  12. Superconductivity research in the Czech Republic

    Czech Academy of Sciences Publication Activity Database

    Jirsa, Miloš

    -, č. 1 (2007), s. 1-6 ISSN N Institutional research plan: CEZ:AV0Z10100520 Keywords : superconductivity * research to superconductivity * financial support of the research Subject RIV: BM - Solid Matter Physics ; Magnetism

  13. Oxygen ordering and superconductivity in DyBaSrCu3Oy

    International Nuclear Information System (INIS)

    Wang, X.Z.; Steger, P.L.; Reissner, M.; Steiner, W.

    1992-01-01

    A new superconducting compound, DyBaSrCu 3 O y , has been synthesized. By different thermal treatments, this compound was crystallized in either orthorhombic or quasitetragonal structure, with oxygen content of y ≅ 6.93 to 6.94. Superconducting properties are similar for both phases. The magnetic moment of the Dy atoms is not influenced by the difference in structures and is close to the value for Dy 3+ . At low temperatures a tendency towards magnetic ordering was observed. (orig.)

  14. Precision picosecond-pulse measurements using a high-quality superconducting delay line

    International Nuclear Information System (INIS)

    Andrews, J.R.

    1974-01-01

    A high-quality superconducting delay line now makes it possible to perform direct oscillographic measurements of the picosecond transition times of very fast electrical signals that do not furnish pretriggers. A 15-m superconducting delay line package has been assembled. The package consists of connectors, connector adapters, normally conducting input/output air lines, and a 15 m length of a miniature 1.6-mm superconducting coaxial transmission line. The package exhibits an attenuation of 0.8 db at 10 GHz and a system 10-90 percent transition time of 18 psec. Some applications of this delay line are shown. They include the measurement of the pulse output from a mercury switch and the transient response of a traveling-wave oscilloscope. 13 refs

  15. Noncentrosymmetric superconductivity in a clean crystal of type II superconductor Bi-Pd

    Science.gov (United States)

    Ramakrishnan, Srinivasan; Pratap, Bhanu; Thamizhavel, A.

    2016-02-01

    In this work, we present the bulk superconductivity of a high-quality single crystal of monoclinic BiPd (α-BiPd, space group P21) below 3.8 K by studying its electrical resistivity, magnetic susceptibility, and heat capacity. This is the cleanest noncentrosymmetric superconductor (NCS) that display anisotropy due to spin-orbit scattering and also exhibits unusual superconducting properties due to s and p wave mixing as evidenced by the observation of Andreev bound state and multiple energy gaps via point contact measurements. In addition, Fermi surface studies suggest multiband superconductivity in this compound. Penetration depth studies and NQR investigations support mixing of s and p wave Copper paring in this crystal. Moroever, Muon spin rotation measurements indicate strong field dependence of the Ginzburg- Landau coefficient of this superconductor. Unusual pairing and multiband superconductivity are extremely sensitive to disorder and they can be observed only in cleanest (RRR > 170) single crystals.

  16. TOPICAL REVIEW: Superconductivity in CVD diamond films

    Science.gov (United States)

    Takano, Yoshihiko

    2009-06-01

    A beautiful jewel of diamond is insulator. However, boron doping can induce semiconductive, metallic and superconducting properties in diamond. When the boron concentration is tuned over 3 × 1020 cm-3, diamonds enter the metallic region and show superconductivity at low temperatures. The metal-insulator transition and superconductivity are analyzed using ARPES, XAS, NMR, IXS, transport and magnetic measurements and so on. This review elucidates the physical properties and mechanism of diamond superconductor as a special superconductivity that occurs in semiconductors.

  17. Superconducting TESLA cavities

    Directory of Open Access Journals (Sweden)

    B. Aune

    2000-09-01

    Full Text Available The conceptional design of the proposed linear electron-positron collider TESLA is based on 9-cell 1.3 GHz superconducting niobium cavities with an accelerating gradient of E_{acc}≥25 MV/m at a quality factor Q_{0}≥5×10^{9}. The design goal for the cavities of the TESLA Test Facility (TTF linac was set to the more moderate value of E_{acc}≥15 MV/m. In a first series of 27 industrially produced TTF cavities the average gradient at Q_{0}=5×10^{9} was measured to be 20.1±6.2 MV/m, excluding a few cavities suffering from serious fabrication or material defects. In the second production of 24 TTF cavities, additional quality control measures were introduced, in particular, an eddy-current scan to eliminate niobium sheets with foreign material inclusions and stringent prescriptions for carrying out the electron-beam welds. The average gradient of these cavities at Q_{0}=5×10^{9} amounts to 25.0±3.2 MV/m with the exception of one cavity suffering from a weld defect. Hence only a moderate improvement in production and preparation techniques will be needed to meet the ambitious TESLA goal with an adequate safety margin. In this paper we present a detailed description of the design, fabrication, and preparation of the TESLA Test Facility cavities and their associated components and report on cavity performance in test cryostats and with electron beam in the TTF linac. The ongoing research and development towards higher gradients is briefly addressed.

  18. On the preparation of superconducting wires

    International Nuclear Information System (INIS)

    Topare, R.J.; Chinchure, A.D.; Shah, S.S.; Hadole, G.B.

    1993-01-01

    The different methods of preparation of superconducting wires have been discussed. The powder-in-tube technique is followed for the preparation of YBCO and BISCCO superconducting wires. The results are discussed. The present status of the industries in preparing the superconducting wires having the maximum J c values is discussed. (author). 30 refs., 6 figs., 2 tabs

  19. Critical current densities in superconducting materials

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    Critical current density; superconducting materials; magnetic-field ... As current densities are raised to higher than JC the material does not go suddenly from the superconducting state to the normal resistive state, but develops a .... to the superconducting state with liquid nitrogen, but whose commercial exploitation has.

  20. Superconducting devices at Brookhaven National Laboratory

    International Nuclear Information System (INIS)

    Dahl, P.F.

    1978-04-01

    The various ongoing programs in applied superconductivity supported by BNL are summarized, including the development of high field ac and dc superconducting magnets for accelerators and other applications, of microwave deflecting cavities for high energy particle beam separators, and of cables for underground power transmission, and materials research on methods of fabricating new superconductors and on metallurgical properties affecting the performance of superconducting devices

  1. Superconducting Metallic Glass Transition-Edge-Sensors

    Science.gov (United States)

    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.

  2. Superconducting Storage Cavity for RHIC

    Energy Technology Data Exchange (ETDEWEB)

    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.

  3. Sensing with Superconducting Point Contacts

    Directory of Open Access Journals (Sweden)

    Argo Nurbawono

    2012-05-01

    Full Text Available 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.

  4. Superconductivity, antiferromagnetism, and neutron scattering

    International Nuclear Information System (INIS)

    Tranquada, John M.; Xu, Guangyong; Zaliznyak, Igor A.

    2014-01-01

    High-temperature superconductivity in both the copper-oxide and the iron–pnictide/chalcogenide systems occurs in close proximity to antiferromagnetically ordered states. Neutron scattering has been an essential technique for characterizing the spin correlations in the antiferromagnetic phases and for demonstrating how the spin fluctuations persist in the superconductors. While the nature of the spin correlations in the superconductors remains controversial, the neutron scattering measurements of magnetic excitations over broad ranges of energy and momentum transfers provide important constraints on the theoretical options. We present an overview of the neutron scattering work on high-temperature superconductors and discuss some of the outstanding issues. - Highlights: • High-temperature superconductivity is closely associated with antiferromagnetism. • Antiferromagnetic spin fluctuations coexist with the superconductivity. • Neutron scattering is essential for characterising the full spectrum of spin excitations

  5. LLNL superconducting magnets test facility

    Energy Technology Data Exchange (ETDEWEB)

    Manahan, R; Martovetsky, N; Moller, J; Zbasnik, J

    1999-09-16

    The FENIX facility at Lawrence Livermore National Laboratory was upgraded and refurbished in 1996-1998 for testing CICC superconducting magnets. The FENIX facility was used for superconducting high current, short sample tests for fusion programs in the late 1980s--early 1990s. The new facility includes a 4-m diameter vacuum vessel, two refrigerators, a 40 kA, 42 V computer controlled power supply, a new switchyard with a dump resistor, a new helium distribution valve box, several sets of power leads, data acquisition system and other auxiliary systems, which provide a lot of flexibility in testing of a wide variety of superconducting magnets in a wide range of parameters. The detailed parameters and capabilities of this test facility and its systems are described in the paper.

  6. Pressure-induced reinforcement of interfacial superconductivity in a Bi2Te3/Fe1+yTe heterostructure

    Science.gov (United States)

    Shen, Junying; Heuckeroth, Claire; Deng, Yuhang; He, Qinglin; Liu, Hong Chao; Liang, Jing; Wang, Jiannong; Sou, Iam Keong; Schilling, James S.; Lortz, Rolf

    2017-12-01

    We investigate the hydrostatic pressure dependence of interfacial superconductivity occurring at the atomically sharp interface between two non-superconducting materials: the topological insulator (TI) Bi2Te3 and the parent compound Fe1+yTe of the chalcogenide iron-based superconductors. Under pressure, a significant increase in the superconducting transition temperature Tc is observed. We interpret our data in the context of a pressure-induced enhanced coupling of the Fe1+yTe interfacial layer with the Bi2Te3 surface state, which modifies the electronic properties of the interface layer in a way that superconductivity emerges and becomes further enhanced under pressure. This demonstrates the important role of the TI in the interfacial superconducting mechanism.

  7. 42 CFR 59a.15 - Awards.

    Science.gov (United States)

    2010-10-01

    ... Establishment of Regional Medical Libraries § 59a.15 Awards. (a) General. The Secretary, with the advice of the... medical library. The Secretary, in determining the priority assigned an applicant, must consider: (1) The...

  8. Power applications for superconducting cables

    DEFF Research Database (Denmark)

    Tønnesen, Ole; Hansen, Steen; Jørgensen, Preben

    2000-01-01

    High temperature superconducting (HTS) cables for use in electric ac power systems are under development around the world today. There are two main constructions under development: the room temperature dielectric design and the cryogenic dielectric design. However, theoretical studies have shown...... that the insertion of these cables in the network is not without problems. The network stability requirements may impose severe constraints on the actual obtainable length of superconducting cables. Load flow considerations show that it may be difficult to use these high current cables to their full extent. Short...

  9. Power applications for superconducting cables

    DEFF Research Database (Denmark)

    Tønnesen, Ole; Hansen, Steen; Jørgensen, Preben

    2000-01-01

    High temperature superconducting (HTS) cables for use in electric ac power systems are under development around the world today. There are two main constructions under development: the room temperature dielectric design and the cryogenic dielectric design. However, theoretical studies have shown...... that the insertion of these cables in the network is not without problems. The network stability requirements may impose severe constraints on the actual obtainable length of superconducting cables. Load flow considerations show that it may be difficult to use these high current cables to their full extent. Short...... circuits in the network may require a special protection system....

  10. Superconducting magnets for fusion reactors

    International Nuclear Information System (INIS)

    Haubenreich, P.N.

    1978-01-01

    Superconducting magnets for fusion reactor applications are being developed in the U.S., Europe, Japan and the USSR. A substantial technological base already exists, but magnets for fusion face special problems and strong incentives for higher performance. In the U.S. high-field magnets for mirrors are being addressed by construction of the superconducting (NbTi) MFTF and by Nb 3 Sn conductor development. Large toroidal field magnets for tokamaks are being developed through the Large Coil Program, which involves design and construction of NbTi and Nb 3 Sn coils by six industrial teams, three in the U.S. and three in other countries

  11. Superconducting augmented rail gun (SARG)

    International Nuclear Information System (INIS)

    Homan, C.G.; Cummings, C.E.; Fowler, C.M.

    1986-01-01

    Superconducting augmentation consists of a superconducting coil operating in the persistent mode closely coupled magnetically with a normally conducting rail gun. A theoretical investigation of the effect of this system on a rail gun has shown that two benefits occur. Projectile velocities and launch efficiencies increase significantly depending on the magnetic coupling between the rail and augmentation circuits. Previous work evaluated an idealized system by neglecting energy dissipation effects. In this paper, the authors extend the analysis to include the neglected terms and show improved actual launch efficiencies for the SARG configuration. In this paper, the authors discuss details of projectile design in depth and present preliminary results of rail gun performance

  12. Superconductivity gets an iron boost.

    Science.gov (United States)

    Mazin, Igor I

    2010-03-11

    Superconductivity, the resistance-free flow of electrical charges, is one of the most exotic phenomena in solid-state physics. Even though it was discovered almost a century ago, many questions remain unanswered, in particular those concerning the physics of high-temperature superconductivity. The recent discovery of iron-based superconductors was arguably the most important breakthrough in this field for more than two decades and may provide new avenues for understanding this high-temperature phenomenon. Here I present my view of the recent developments in this field that have led to the current understanding of this important new class of superconductor.

  13. Diamagnetism in quasicrystalline superconducting networks

    International Nuclear Information System (INIS)

    Qian Niu; Nori, F.

    1990-01-01

    In this paper, we review recent results on superconducting structures with quasicrystalline geometry. Specifically, we consider the superconducting-normal phase boundaries of a variety of wire networks and Josephson junction arrays. We have computed the mean field phase diagrams for a number of geometries and compared them to the corresponding experimental data. We have introduced an analytical approach to the analysis of the structures present in the phase boundaries. Furthermore, we have shown in great detail how the gross structure is determined by the statistical distributions of the cell areas, and how the fine structures are determined by correlations among neighboring cells in the lattices. (author). 12 refs, 2 figs

  14. Freely oriented portable superconducting magnet

    Science.gov (United States)

    Schmierer, Eric N [Los Alamos, NM; Prenger, F Coyne [Los Alamos, NM; Hill, Dallas D [Los Alamos, NM

    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.

  15. Research Progress on Ni-Based Antiperovskite Compounds

    Directory of Open Access Journals (Sweden)

    P. Tong

    2012-01-01

    Full Text Available The superconductivity in antiperovskite compound MgCNi3 was discovered in 2001 following the discovery of the superconducting MgB2. In spite of its lower superconducting transition temperature (8 K than MgB2 (39 K, MgCNi3 has attracted considerable attention due to its high content of magnetic element Ni and the cubic structure analogous to the perovskite cuprates. After years of extensive investigations both theoretically and experimentally, however, it is still not clear whether the mechanism for superconductivity is conventional or not. The central issue is if and how the ferromagnetic spin fluctuations contribute to the cooper paring. Recently, the experimental results on the single crystals firstly reported in 2007 trend to indicate a conventional s-wave mechanism. Meanwhile many compounds neighboring to MgCNi3 were synthesized and the physical properties were investigated, which enriches the physics of the Ni-based antiperovskite compounds and help understand the superconductivity in MgCNi3. In this paper, we summarize the research progress in these two aspects. Moreover, a universal phase diagram of these compounds is presented, which suggests a phonon-mediated mechanism for the superconductivity, as well as a clue for searching new superconductors with the antiperovskite structure. Finally, a few possible scopes for future research are proposed.

  16. Status of superconducting power transformer development

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, R.C.; McConnell, B.W.; Mehta, S.P. [and others

    1996-03-01

    Development of the superconducting transformer is arguably the most difficult of the ac power applications of superconductivity - this is because of the need for very low ac losses, adequate fault and surge performance, and the rigors of the application environment. This paper briefly summarizes the history of superconducting transformer projects, reviews the key issues for superconducting transformers, and examines the status of HTS transformer development. Both 630-kVA, three-phase and 1-MVA single phase demonstration units are expected to operate in late 1996. Both efforts will further progress toward the development of economical and performance competitive superconducting transformers.

  17. Bec Model of HIGH-Tc Superconductivity in Layered Cuprates

    Science.gov (United States)

    Lomnitz, M.; Villarreal, C.; de Llano, M.

    2013-11-01

    High-Tc superconductivity in layered cuprates is described in a BCS-BEC formalism with linearly-dispersive s- and d-wave Cooper pairs moving in quasi-2D finite-width layers around the CuO2 planes. This yields a closed formula for Tc involving the layer width, the Debye frequency, the pairing energy and the in-plane penetration depth. The new formula has no free parameters and reasonably reproduces empirical values of superconducting Tcs for 11 different layered superconductors over a wide doping regime including YBCO itself as well as other compounds like LSCO, BSCCO and TBCCO. In agreement with the London formalism, the formula also yields a fair description of the Tc dependence of the lower critical magnetic field in highly underdoped YBCO.

  18. Spin-Lattice Coupling and Superconductivity in Fe Pnictides

    Directory of Open Access Journals (Sweden)

    T. Egami

    2010-01-01

    Full Text Available We consider strong spin-lattice and spin-phonon coupling in iron pnictides and discuss its implications on superconductivity. Strong magneto-volume effect in iron compounds has long been known as the Invar effect. Fe pnictides also exhibit this effect, reflected in particular on the dependence of the magnetic moment on the atomic volume of Fe defined by the positions of the nearest neighbor atoms. Through the phenomenological Landau theory, developed on the basis of the calculations by the density functional theory (DFT and the experimental results, we quantify the strength of the spin-lattice interaction as it relates to the Stoner criterion for the onset of magnetism. We suggest that the coupling between electrons and phonons through the spin channel may be sufficiently strong to be an important part of the superconductivity mechanism in Fe pnictides.

  19. Unconventional Superconductivity in La(7)Ir(3) Revealed by Muon Spin Relaxation: Introducing a New Family of Noncentrosymmetric Superconductor That Breaks Time-Reversal Symmetry.

    Science.gov (United States)

    Barker, J A T; Singh, D; Thamizhavel, A; Hillier, A D; Lees, M R; Balakrishnan, G; Paul, D McK; Singh, R P

    2015-12-31

    The superconductivity of the noncentrosymmetric compound La(7)Ir(3) is investigated using muon spin rotation and relaxation. Zero-field measurements reveal the presence of spontaneous static or quasistatic magnetic fields below the superconducting transition temperature T(c)=2.25  K-a clear indication that the superconducting state breaks time-reversal symmetry. Furthermore, transverse-field rotation measurements suggest that the superconducting gap is isotropic and that the pairing symmetry of the superconducting electrons is predominantly s wave with an enhanced binding strength. The results indicate that the superconductivity in La(7)Ir(3) may be unconventional and paves the way for further studies of this family of materials.

  20. Superconducting wires and methods of making thereof

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Xingchen; Sumption, Michael D.; Peng, Xuan

    2018-03-13

    Disclosed herein are superconducting wires. The superconducting wires can comprise a metallic matrix and at least one continuous subelement embedded in the matrix. Each subelement can comprise a non-superconducting core, a superconducting layer coaxially disposed around the non-superconducting core, and a barrier layer coaxially disposed around the superconducting layer. The superconducting layer can comprise a plurality of Nb.sub.3Sn grains stabilized by metal oxide particulates disposed therein. The Nb.sub.3Sn grains can have an average grain size of from 5 nm to 90 nm (for example, from 15 nm to 30 nm). The superconducting wire can have a high-field critical current density (J.sub.c) of at least 5,000 A/mm.sup.2 at a temperature of 4.2 K in a magnetic field of 12 T. Also described are superconducting wire precursors that can be heat treated to prepare superconducting wires, as well as methods of making superconducting wires.

  1. Structural changes and the nature of superconductivity in rare-earth doped CaFe2As2

    Science.gov (United States)

    Drye, Tyler

    Chemical substitution into iron-pnictide parent compounds (e.g. AFe2As2 where A=Ba, Sr, or Ca) has proven to be an effective means to induce bulk high-temperature superconductivity in these systems. By doping CaFe2As2 with rare-earth lanthanides (La, Ce, Pr, and Nd), we have observed a 47 K superconducting phase coexisting with a lattice distorting "collapse" transition. Both of these effects have important ramifications: the collapse transition occurs when interlayer As atoms form a bond, shrinking the c-axis lattice constant and simultaneously quenching the iron magnetic moment. This transition is further explored in context of a similar system, Sr-doped BaNi2As2. The superconducting phase, given the right combination of conditions, appears with a critical temperature as high as 49 K, but always in a very small volume of the sample (as determined by shielding effects). This has led to interesting theories about the nature of this superconductivity. A recently posited idea of "interfacial superconductivity" has been ruled out by our tests. Additionally, increasing the concentration of rare-earth atoms does not increase the superconducting volume fraction, but, in fact lowers the transition temperature, excluding the hypothesis that rare-earth defects are responsible for the minority superconducting phase. New pressure measurements have shown that the superconducting phase is stabilized when antiferromagnetic order is fully suppressed.

  2. Superconductivity of metallic aluminum antimonide.

    Science.gov (United States)

    Wittig, J

    1967-02-10

    The high-pressure metallic phase of aluminunm antimnonide is super conducting [critical temperature T(c) (P approximately 125 kilobars) = 2.8 degrees +/-0.2 degrees K]. This transition temperature is significantly lower than the transition temperature of metallic germanium under an equivalent high pressure. A similar result had been previously found for superconducting indiumantimonide in comparison to tin.

  3. Superconducting cavity model for LEP

    CERN Document Server

    CERN PhotoLab

    1979-01-01

    A superconducting cavity model is being prepared for testing in a vertical cryostat.At the top of the assembly jig is H.Preis while A.Scharding adjusts some diagnostic equipment to the cavity. See also photo 7912501X.

  4. Photon-detecting superconducting resonators

    NARCIS (Netherlands)

    Barends, R.

    2009-01-01

    One of the greatest challenges in astronomy is observing star and planetary formation, redshifted distant galaxies and molecular spectral ‘fingerprints’ in the far-infrared spectrum of light, using highly sensitive and large cameras. In this thesis we investigate superconducting resonators for

  5. Discovering superconductivity an investigative approach

    CERN Document Server

    Ireson, Gren

    2012-01-01

    The highly-illustrated text will serve as excellent introduction for students, with and without a physics background, to superconductivity. With a strong practical, experimental emphasis, it will provide readers with an overview of the topic preparing them for more advanced texts used in more advanced undergraduate and post-graduate courses.

  6. Superconducting Qubits and Quantum Resonators

    NARCIS (Netherlands)

    Forn-Díaz, P.

    2010-01-01

    Superconducting qubits are fabricated "loss-free" electrical circuits on a chip with size features of tens of nanometers. If cooled to cryogenic temperatures below -273 °C they behave as quantum elements, similar to atoms and molecules. Such a qubit can be manipulated by fast-oscillating magnetic

  7. Vacuum Technology for Superconducting Devices

    CERN Document Server

    Chiggiato, P

    2014-01-01

    The basic notions of vacuum technology for superconducting applications are presented, with an emphasis on mass and heat transport in free molecular regimes. The working principles and practical details of turbomolecular pumps and cryopumps are introduced. The specific case of the Large Hadron Collider’s cryogenic vacuum system is briefly reviewed.

  8. ISR Superconducting High luminosity Insertion

    CERN Multimedia

    1981-01-01

    The picture shows two of the eight superconducting quadrupoles of the low-beta insertion at intersection I8.The increase of luminosity produced by this insertion was above a factor 7. At right one can also see the Open- Axial- Field Magnet. The person is Stephan Pichler. See also 7702690X, 8102123, 8010397, 8008332.

  9. Superconducting magnets and cryogenics: proceedings

    International Nuclear Information System (INIS)

    Dahl, P.F.

    1986-01-01

    Separate abstracts were prepared for 70 papers in these workshop proceeedings. Topics covered include: superconducting accelerator magnet research and development; superconductor development; electrical measurements; magnet design and construction methods; field correction methods; power schemes and quench protection; cryogenic systems; and magnet measurements

  10. Collaring of Po Superconducting Dipole

    CERN Multimedia

    1983-01-01

    The picture shows the placing of a stack of stainless steel collars around the superconducting coils.Pre-assembled collar stacks were placed under and on top of the coils,the collars interleaving as comb teeth. During the following collaring operation of compression under a press the collars were locked together by means of side wedges. See also photos 8211532X, 7903168

  11. Monolayer Superconductivity in WS2

    NARCIS (Netherlands)

    Zheliuk, Oleksandr; Lu, Jianming; Yang, Jie; Ye, Jianting

    Superconductivity in monolayer tungsten disulfide (2H-WS2) is achieved by strong electrostatic electron doping of an electric double-layer transistor (EDLT). Single crystals of WS2 are grown by a scalable method - chemical vapor deposition (CVD) on standard Si/SiO2 substrate. The monolayers are

  12. Topological Properties of Superconducting Junctions

    NARCIS (Netherlands)

    Pikulin, D.I.; Nazarov, Y.V.

    Motivated by recent developments in the field of one-dimensional topological superconductors, we investigate the topological properties of s-matrix of generic superconducting junctions where dimension should not play any role. We argue that for a finite junction the s-matrix is always topologically

  13. structure-chemical analyses of half-antiperovskites and superconductivity of parkerites; Strukturchemische Untersuchungen an Halbantiperowskiten und Supraleitung der Parkerite

    Energy Technology Data Exchange (ETDEWEB)

    Peter, Philipp

    2015-04-22

    The aim of this work was the structural investigation on Halfantiperowskites. In the process four new compounds were synthesized and a new ordering variant was found. Furthermore superconductivity was measured on selected compounds of the Parkerite-type of structure and an attempt was made to change the transition temperature by selective doping.

  14. Powder of a copper oxide superconductor precursor, fabrication process and use for the preparation of superconducting oxide

    International Nuclear Information System (INIS)

    Dehaudt, P.

    1990-01-01

    The precursor powder comprises at least a copper compound (hydroxide, oxide and hydroxynitrates), at least a rare earth and/or yttrium compound (nitrates, hydroxides and hydroxynitrates) or bismuth oxide and at least an alkaline earth nitrate. It can be prepared by atomization drying of a suspension a copper precipitate or coprecipitate and other elements of the superconducting oxide in solution [fr

  15. Mesoionic Compounds

    Indian Academy of Sciences (India)

    property has been used to determine whether a compound is aromatic or not. Mesoionic compounds are structurally very different from ben- zenoid compounds, but they fulfill most of the criteria of aroma- ticity and form a part of a variety of aromatic compounds, which can be classified as follows. A) Benzenoid Compounds.

  16. Superconductivity in the YIr2Si2 and LaIr2Si2 Polymorphs

    Science.gov (United States)

    Vališka, Michal; Pospíšil, Jiří; Prokleška, Jan; Diviš, Martin; Rudajevová, Alexandra; Sechovský, Vladimír

    2012-10-01

    We report on the existence of superconductivity in YIr2Si2 and LaIr2Si2 compounds in relation to the crystal structure. The two compounds crystallize in two structural polymorphs, both tetragonal. The high-temperature polymorph (HTP) is of the CaBe2Ge2 structure type (space group P4/nmm), while the low-temperature polymorph (LTP) is of the ThCr2Si2 structure type (I4/mmm). By studying the polycrystals prepared by arc melting, we observed that the rapidly cooled samples retain the HTP even at room temperature (RT) and below. Annealing such samples at ≥900 °C followed by slow cooling to RT provides the LTP. Both the HTP and LTP were subsequently studied with respect to magnetism and superconductivity by electrical resistivity, magnetization, AC susceptibility, and specific heat measurements. The HTP and LTP of both compounds behave as Pauli paramagnets. Superconductivity was found exclusively in the HTP of both compounds below TSC (= 2.52 K in YIr2Si2 and 1.24 K in LaIr2Si2). The relationships of magnetism and superconductivity with the electronic and crystal structures are discussed by comparing experimental data with the results of first-principles electronic structure calculations.

  17. Endohedral gallide cluster superconductors and superconductivity in ReGa5

    Science.gov (United States)

    Xie, Weiwei; Luo, Huixia; Phelan, Brendan F.; Klimczuk, Tomasz; Cevallos, Francois Alexandre; Cava, Robert Joseph

    2015-01-01

    We present transition metal-embedded (T@Gan) endohedral Ga-clusters as a favorable structural motif for superconductivity and develop empirical, molecule-based, electron counting rules that govern the hierarchical architectures that the clusters assume in binary phases. Among the binary T@Gan endohedral cluster systems, Mo8Ga41, Mo6Ga31, Rh2Ga9, and Ir2Ga9 are all previously known superconductors. The well-known exotic superconductor PuCoGa5 and related phases are also members of this endohedral gallide cluster family. We show that electron-deficient compounds like Mo8Ga41 prefer architectures with vertex-sharing gallium clusters, whereas electron-rich compounds, like PdGa5, prefer edge-sharing cluster architectures. The superconducting transition temperatures are highest for the electron-poor, corner-sharing architectures. Based on this analysis, the previously unknown endohedral cluster compound ReGa5 is postulated to exist at an intermediate electron count and a mix of corner sharing and edge sharing cluster architectures. The empirical prediction is shown to be correct and leads to the discovery of superconductivity in ReGa5. The Fermi levels for endohedral gallide cluster compounds are located in deep pseudogaps in the electronic densities of states, an important factor in determining their chemical stability, while at the same time limiting their superconducting transition temperatures. PMID:26644566

  18. Energy band theory of heterometal superposed film and relevant comments on superconductivity in heterometal systems

    International Nuclear Information System (INIS)

    Zhang, L.; Yin, D.

    1981-08-01

    A method for calculating the electronic structure of a heterogeneous metal-metal interface is discussed. It combines a series of well-defined interface plane-wave orbitals and the muffin-tin orbitals. The problem of high-Tsub(c) superconductivity in systems containing metal-metal interfaces and the related problem in compounds is addressed

  19. High-temperature superconducting fault-current limiter - optimisation of superconducting elements

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2004-07-01

    This report summarises the findings of a study initiated to continue the work of a DTI-LINK Collaborative Research Programme 'Enhancing the Properties of Bulk High Temperature Superconductors and their Potential Application as Fault Current Limiters (FCL). Details are given of computer modelling of the quenching process involving the transition from superconducting to normal conducting states undergone by the material when large currents are present. The design of compound elements, and a multi-element model are described along with FCL design covering distribution bus-coupler, embedded generator connection, larger generator connection, hazardous area safety, and interconnection to fault-prone network. The evaluation of thermal loss, test equipment and schedule, the optimised element, installed cost data, and the UK market are considered.

  20. Superconducting magnets. B. Superconducting magnet systems in EPR designs

    International Nuclear Information System (INIS)

    Knobloch, A.F.

    1978-01-01

    Tokamak experiments have reached a stage where large scale application of superconductors can be envisaged for machines becoming operational within the next decade. Existing designs for future devices already indicate some of the tasks and problems associated with large superconducting magnet systems. Using this information the coming magnet system requirements are summarized, some design considerations given and in conclusion a brief survey describes already existing Tokamak magnet development programs

  1. Once upon a time, there was a brittle but superconducting niobium-tin…

    CERN Document Server

    Stefania Pandolfi

    2016-01-01

    The production of the new niobium-tin cables for the high-performance superconducting magnets of the HL-LHC is now in full swing at CERN.   The Rutherford cabling machine is operating in the superconducting laboratory, in Building 163. (Photo: Max Brice/CERN) Extraordinary research needs extraordinary machines: the upgrade project of the LHC, the High-Luminosity LHC (HL-LHC), has the goal of achieving instantaneous luminosities a factor of five larger than the LHC nominal value, and it relies on magnetic fields reaching the level of 12 Tesla. The superconducting niobium-titanium (Nb-Ti) used in the LHC magnets can only bear magnetic fields of up to 9-10 Tesla. Therefore, an alternative solution for the superconducting magnets materials was needed. The key innovative technology to develop superconducting magnets beyond 10 Tesla has been found in the niobium-tin (Nb3Sn)  compound. This compound was actually discovered in 1954, eight years before Nb-Ti, but when the LHC was built, ...

  2. Improvement of small to large grain A15 ratio in Nb3Sn PIT wires by inverted multistage heat treatments

    Science.gov (United States)

    Segal, Christopher; Tarantini, Chiara; Lee, Peter J.; Larbalestier, David C.

    2017-12-01

    The next generation of superconducting accelerator magnets for the Large Hadron Collider at CERN will require large amounts of Nb3Sn superconducting wires and the Powder-In-Tube (PIT) process, which utilizes a NbSn2-rich powder core within tubes of Nb(7.5wt%Ta) contained in a stabilizing Cu matrix, is a potential candidate. However, the critical current density, J c , is limited by the formation of a large grain (LG) A15 layer which does not contribute to transport current, but occupies 25-30% of the total A15 area. Thus it is important to understand how this layer forms, and if it can be minimized in favor of the beneficial small grain (SG) A15 morphology which carries the supercurrent. The ratio of SG/LG A15 is our metric here, where an increase signals improvement in the wires A15 morphology distribution. We have made a critical new observation that the initiation of the LG A15 formation can be controlled at a wide range of temperatures relative to the formation of the small grain (SG) A15. The LG A15 can be uniquely identified as a decomposition product of the Nb6Sn5(Cu x ), surrounded by a layer of rejected Cu, thus the LG A15 is not only of low pin density, but is not continuous grain to grain. We have found that in single stage reactions limited to 630 °C - 690 °C, the maximum SG A15 layer thickness prior to LG A15 formation is very sensitive to temperature, with a maximum around 670 °C. This result led to the design of four novel heat treatments which all included a short, high temperature stage early in the reaction, followed by a slow cooling to a more typical reaction temperature of 630 °C. We found that this heat treatment (HT) modification increased the SG A15 layer thickness while simultaneously suppressing LG A15 morphology, with no additional consumption of the diffusion barrier. In the best heat treatment the SG/LG A15 ratio improved by 30%. Unfortunately, J c values suffered slightly, however further exploration of this high temperature

  3. Characterizing Ensembles of Superconducting Qubits

    Science.gov (United States)

    Sears, Adam; Birenbaum, Jeff; Hover, David; Rosenberg, Danna; Weber, Steven; Yoder, Jonilyn L.; Kerman, Jamie; Gustavsson, Simon; Kamal, Archana; Yan, Fei; Oliver, William

    We investigate ensembles of up to 48 superconducting qubits embedded within a superconducting cavity. Such arrays of qubits have been proposed for the experimental study of Ising Hamiltonians, and efficient methods to characterize and calibrate these types of systems are still under development. Here we leverage high qubit coherence (> 70 μs) to characterize individual devices as well as qubit-qubit interactions, utilizing the common resonator mode for a joint readout. This research was funded by the Office of the Director of National Intelligence (ODNI), Intelligence Advanced Research Projects Activity (IARPA) under Air Force Contract No. FA8721-05-C-0002. The views and conclusions contained herein are those of the authors and should not be interpreted as necessarily representing the official policies or endorsements, either expressed or implied, of ODNI, IARPA, or the US Government.

  4. Siting the superconducting super collider

    International Nuclear Information System (INIS)

    Price, R.; Rooney, R.C.

    1988-01-01

    At the request of the Department of Energy, the National Academy of Sciences and the National Academy of Engineering established the Super Collider Site Evaluation Committee to evaluate the suitability of proposed sites for the Superconducting Super Collider. Thirty-six proposals were examined by the committee. Using the set of criteria announced by DOE in its Invitation for Site Proposals, the committee identified eight sites that merited inclusion on a ''best qualified list.'' The list represents the best collective judgment of 21 individuals, carefully chosen for their expertise and impartiality, after a detailed assessment of the proposals using 19 technical subcriteria and DOE's life cycle cost estimates. The sites, in alphabetical order, are: Arizona/Maricopa; Colorado; Illinois; Michigan/Stockbridge; New York/Rochester; North Carolina; Tennessee; and Texas/Dallas-Fort Worth. The evaluation of these sites and the Superconducting Super Collider are discussed in this book

  5. Development of Superconducting Wind Turbine Generators

    DEFF Research Database (Denmark)

    Jensen, Bogi Bech; Mijatovic, Nenad; Abrahamsen, Asger Bech

    2012-01-01

    speeds, because high magnetic fields can be produced by coils with very little loss. Three different superconducting wind turbine generator topologies have been proposed by three different companies. One is based on low temperature superconductors (LTS); one is based on high temperature superconductors......In this paper the commercial activities in the field of superconducting machines, particularly superconducting wind turbine generators, are reviewed and presented. Superconducting generators have the potential to provide a compact and light weight drive train at high torques and slow rotational...... (HTS); and one is a fully superconducting generator based on MgB2. It is concluded that there is large commercial interest in superconducting machines, with an increasing patenting activity. Such generators are however not without their challenges. The superconductors have to be cooled down...

  6. Development of superconducting wind turbine generators

    DEFF Research Database (Denmark)

    Jensen, Bogi Bech; Mijatovic, Nenad; Abrahamsen, Asger Bech

    2013-01-01

    speeds, because high magnetic fields can be produced by coils with very little loss. Three different superconducting wind turbine generator topologies have been proposed by three different companies. One is based on low temperature superconductors; one is based on high temperature superconductors......In this paper, the commercial activities in the field of superconducting machines, particularly superconducting wind turbine generators, are reviewed and presented. Superconducting generators have the potential to provide a compact and light weight drive train at high torques and slow rotational......; and one is a fully superconducting generator based on MgB2. It is concluded that there is large commercial interest in superconducting machines, with an increasing patenting activity. Such generators are, however, not without their challenges. The superconductors have to be cooled down to somewhere...

  7. Superconductivity in the lanthanum-yttrium-manganese alloy system

    International Nuclear Information System (INIS)

    Stierman, R.J.

    1980-03-01

    An empirical approach involving lattice instabilities was investigated in the search for new superconducting materials. Pseudo-lanthanide compounds using La and Y were prepared for the system La/sub 1-x/Y/sub x/Mn 2 by arc melting and subsequent heat treatment. Low temperature magnetic susceptibility and low temperature heat capacity measurements were made. The unit cell lattice parameters were determined from x-ray powder patterns taken on most samples and metallographic examination was carried out on selected samples. Alloys with low La concentrations (x greater than or equal to 0.6) showed RMn 2 in the cubic C15 Laves phase as the major component with second phase material present. The magnetic susceptibility and x-ray data indicated a superconducting phase which seemed to be the RMn 2 phase, but heat capacity measurements showed the second phase material was the superconductor, while the RMn 2 was not. Failure to form compounds with higher La content was experienced and may be due to the lattice instability expected at x = 0.56. This indicates that perhaps more stingent conditions are required to form pseudo-lanthanide compounds than were previously considered. More systems should be investigated to see if this is true, and to determine the possibilities of this approach

  8. Stimulated Superconductivity at Strong Coupling

    Energy Technology Data Exchange (ETDEWEB)

    Bao, Ning; Dong, Xi; Silverstein, Eva; Torroba, Gonzalo; /Stanford U., ITP /Stanford U., Phys. Dept. /SLAC

    2011-08-12

    Stimulating a system with time dependent sources can enhance instabilities, thus increasing the critical temperature at which the system transitions to interesting low-temperature phases such as superconductivity or superfluidity. After reviewing this phenomenon in non-equilibrium BCS theory (and its marginal fermi liquid generalization) we analyze the effect in holographic superconductors. We exhibit a simple regime in which the transition temperature increases parametrically as we increase the frequency of the time-dependent source.

  9. Terahertz superconducting plasmonic hole array

    OpenAIRE

    Tian, Zhen; Singh, Ranjan; Han, Jiaguang; Gu, Jianqiang; Xing, Qirong; Zhang, Weili

    2010-01-01

    We demonstrate thermally tunable superconductor hole array with active control over their resonant transmission induced by surface plasmon polaritons . The array was lithographically fabricated on high temperature YBCO superconductor and characterized by terahertz-time domain spectroscopy. We observe a clear transition from the virtual excitation of the surface plasmon mode to the real surface plasmon mode. The highly tunable superconducting plasmonic hole arrays may have promising applicatio...

  10. Superconducting Planar Devices for Cosmology

    Science.gov (United States)

    Ghribi, A.; Bélier, B.; Boussaha, F.; Bréelle, E.; Piat, M.; Spinelli, S.; Tartari, A.; Zannoni, M.

    2009-12-01

    To enhance systematics cleaness of a new advanced detection architecture for B-modes detection of the Cosmic Microwave Background polarization and in the framework of the ground based instrument QUBIC (Q and U Bolometric Interferometer for Cosmology), we study planar superconducting devices. Waveguide to microstrip transition, orthomode transducer and phase switches are therefore investigated as well as their cryogenic characterization at millimeter waves. We also show design and nanotechnology fabrication process of these devices.

  11. Superconductivity, Antiferromagnetism, and Neutron Scattering

    OpenAIRE

    Tranquada, John M.; Xu, Guangyong; Zaliznyak, Igor A.

    2013-01-01

    High-temperature superconductivity in both the copper-oxide and the iron-pnictide/chalcogenide systems occurs in close proximity to antiferromagnetically ordered states. Neutron scattering has been an essential technique for characterizing the spin correlations in the antiferromagnetic phases and for demonstrating how the spin fluctuations persist in the superconductors. While the nature of the spin correlations in the superconductors remains controversial, the neutron scattering measurements...

  12. Superconductivity in compensated and uncompensated semiconductors

    OpenAIRE

    Yanase, Youichi; Yorozu, Naoyuki

    2009-01-01

    We investigate the localization and superconductivity in heavily doped semiconductors. The crossover from the superconductivity in the host band to that in the impurity band is described on the basis of the disordered three-dimensional attractive Hubbard model for binary alloys. The microscopic inhomogeneity and the thermal superconducting fluctuation are taken into account using the self-consistent 1-loop order theory. The superconductor-insulator transition accompanies the crossover from th...

  13. Realization of superconductive films by screen printing

    International Nuclear Information System (INIS)

    Baudry, H.

    1988-01-01

    Screen printing is a promising method to manufacture superconductive lines making use of superconductive ceramics. An ink has been realized with YBa 2 Cu 3 0 7-x' and the process conditions defined by thermal analysis. A superconductive transition is observed after screen printing on MgO. The firing of the layer is made at 920 0 C followed by a reoxidation step at 420 0 C. The silver electrical contacts are also screen printed [fr

  14. Anelastic spectroscopy in superconducting oxides

    International Nuclear Information System (INIS)

    Albuquerque Gimenez, J.M. de; Grandini, C.R.; Santos, D.L. dos; Cunha, A.G. da

    2005-01-01

    Since the discovery of the high Tc superconductors, several works have been made about the different properties of these materials. Anelastic spectroscopy experiments are sensitive tools to the study of defects in solids and phase transitions. By this technique, we can distinguish the different types of atomic jumps that happen to different temperatures. The intensity of the peaks in the anelastic spectrum and the ''step'' in the torsional modulus are related with the concentration of the relaxing entities, and the position of the peaks is determined by its mobility. In this paper, the study on Bi and Sm based superconducting oxides was made by anelastic relaxation measurements using a torsion pendulum. The samples were submitted to successive thermal treatments in high vacuum, in the temperature range between 100 K and 650 K, heating rate about 1 K/min. For Bi based superconducting oxides the results shown two peaks, that were associated to interstitial oxygen mobility and to orthorhombic to monoclinic phase transition. For Sm based superconducting oxides the results shown a relaxation peak that was attributed to the jumps of the oxygen atoms in the inter-chains O1 and O5 of the lattice. (orig.)

  15. Anelastic spectroscopy in superconducting oxides

    Energy Technology Data Exchange (ETDEWEB)

    Albuquerque Gimenez, J.M. de [USP, Inst. de Fisica de Sao Carlos, Sao Carlos, SP (Brazil); UNESP, Dept. de Fisica, Bauru, SP (Brazil); Grandini, C.R.; Santos, D.L. dos [UNESP, Dept. de Fisica, Bauru, SP (Brazil); Cunha, A.G. da [UFES, Dept. de Fisica, Vitoria, ES (Brazil)

    2005-07-01

    Since the discovery of the high Tc superconductors, several works have been made about the different properties of these materials. Anelastic spectroscopy experiments are sensitive tools to the study of defects in solids and phase transitions. By this technique, we can distinguish the different types of atomic jumps that happen to different temperatures. The intensity of the peaks in the anelastic spectrum and the ''step'' in the torsional modulus are related with the concentration of the relaxing entities, and the position of the peaks is determined by its mobility. In this paper, the study on Bi and Sm based superconducting oxides was made by anelastic relaxation measurements using a torsion pendulum. The samples were submitted to successive thermal treatments in high vacuum, in the temperature range between 100 K and 650 K, heating rate about 1 K/min. For Bi based superconducting oxides the results shown two peaks, that were associated to interstitial oxygen mobility and to orthorhombic to monoclinic phase transition. For Sm based superconducting oxides the results shown a relaxation peak that was attributed to the jumps of the oxygen atoms in the inter-chains O1 and O5 of the lattice. (orig.)

  16. Attenuation in Superconducting Circular Waveguides

    Directory of Open Access Journals (Sweden)

    K. H. Yeap

    2016-09-01

    Full Text Available We present an analysis on wave propagation in superconducting circular waveguides. In order to account for the presence of quasiparticles in the intragap states of a superconductor, we employ the characteristic equation derived from the extended Mattis-Bardeen theory to compute the values of the complex conductivity. To calculate the attenuation in a circular waveguide, the tangential fields at the boundary of the wall are first matched with the electrical properties (which includes the complex conductivity of the wall material. The matching of fields with the electrical properties results in a set of transcendental equations which is able to accurately describe the propagation constant of the fields. Our results show that although the attenuation in the superconducting waveguide above cutoff (but below the gap frequency is finite, it is considerably lower than that in a normal waveguide. Above the gap frequency, however, the attenuation in the superconducting waveguide increases sharply. The attenuation eventually surpasses that in a normal waveguide. As frequency increases above the gap frequency, Cooper pairs break into quasiparticles. Hence, we attribute the sharp rise in attenuation to the increase in random collision of the quasiparticles with the lattice structure.

  17. Test Bed for Superconducting Materials

    CERN Document Server

    Nantista, C D; Dolgashev, Valery A; Siemann, Robert; Tantawi, Sami G; Weisend, John

    2005-01-01

    Superconducting rf cavities are increasingly used in accelerators. Gradient is a parameter of particular importance for the ILC. Much progress in gradient has been made over the past decade, overcoming problems of multipacting, field emission, and breakdown triggered by surface impurities. However, the quenching limit of the surface magnetic field for niobium remains a hard limitation on cavity fields sustainable with this technology. Further exploration of materials and preparation may offer a path to surpassing the current limit. For this purpose, we have designed a resonant test cavity. One wall of the cavity is formed by a flat sample of superconducting material; the rest of the cavity is copper or niobium. The H field on the sample wall is 74% higher than on any other surface. Multipacting is avoided by use of a mode with no surface electric field. The cavity will be resonated through a coupling iris with high-power rf at superconducting temperature until the sample wall quenches, as detected by a change...

  18. Superconducting microtraps for ultracold atoms

    International Nuclear Information System (INIS)

    Hufnagel, C.

    2011-01-01

    Atom chips are integrated devices in which atoms and atomic clouds are stored and manipulated in miniaturized magnetic traps. State of the art fabrication technologies allow for a flexible design of the trapping potentials and consequently provide extraordinary control over atomic samples, which leads to a promising role of atom chips in the engineering and investigation of quantum mechanical systems. Naturally, for quantum mechanical applications, the atomic coherence has to be preserved. Using room temperature circuits, the coherence time of atoms close to the surface was found to be drastically limited by thermal current fluctuations in the conductors. Superconductors offer an elegant way to circumvent thermal noise and therefore present a promising option for the coherent manipulation of atomic quantum states. In this thesis trapping and manipulation of ultracold Rubidium atoms in superconducting microtraps is demonstrated. In this connection the unique properties of superconductors are used to build traps based on persistent currents, the Meissner effect and remanent magnetization. In experiment it is shown, that in superconducting atom chips, thermal magnetic field noise is significantly reduced. Furthermore it is demonstrated, that atomic samples can be employed to probe the properties of superconducting materials. (author) [de

  19. Search for superconductivity of magnetic metals

    Energy Technology Data Exchange (ETDEWEB)

    Amaya, K [Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531 (Japan); Furomoto, S [Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531 (Japan); Kimura, T [Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531 (Japan); Shimizu, K [Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531 (Japan); Onuki, Y [Graduate School of Science, Osaka University, Toyonaka, Osaka 560-8531 (Japan)

    2002-11-11

    A search for superconductivity of magnetic elemental metals is performed. A successful discovery of the onset of superconductivity is reported in the case of iron under pressure. By electrical resistance measurement, a maximum value of the superconducting transition temperature T{sub c} of 2 K and the upper critical magnetic field H{sub c} of 0.2 T are observed under pressure of 20 GPa where iron is in the crystallographic hcp phase and non-magnetic. Further confirmation of the superconducting transition of hcp iron was obtained by the detection of the diamagnetic signal due to the Meissner effect in accordance with the results of the electrical resistance measurements.

  20. Search for superconductivity of magnetic metals

    CERN Document Server

    Amaya, K; Kimura, T; Shimizu, K; Onuki, Y

    2002-01-01

    A search for superconductivity of magnetic elemental metals is performed. A successful discovery of the onset of superconductivity is reported in the case of iron under pressure. By electrical resistance measurement, a maximum value of the superconducting transition temperature T sub c of 2 K and the upper critical magnetic field H sub c of 0.2 T are observed under pressure of 20 GPa where iron is in the crystallographic hcp phase and non-magnetic. Further confirmation of the superconducting transition of hcp iron was obtained by the detection of the diamagnetic signal due to the Meissner effect in accordance with the results of the electrical resistance measurements.

  1. Inhomogeneous Stripe Phase Revisited for Surface Superconductivity

    Science.gov (United States)

    Barzykin, Victor; Gor'kov, Lev P.

    2002-11-01

    We consider 2D surface superconductivity in high magnetic fields parallel to the surface. We demonstrate that the spin-orbit interaction at the surface changes the properties of the inhomogeneous superconducting Larkin-Ovchinnikov-Fulde-Ferrell (LOFF) state that develops above fields given by the paramagnetic criterion. Strong spin-orbit interaction significantly broadens the range of existence of the LOFF phase, which takes the form of periodic superconducting stripes running along the field direction on the surface, leading to the anisotropy of its properties. Our results provide a tool for studying surface superconductivity as a function of doping.

  2. Mechanical Design of Superconducting Accelerator Magnets

    CERN Document Server

    Toral, Fernando

    2014-07-17

    This paper is about the mechanical design of superconducting accelerator magnets. First, we give a brief review of the basic concepts and terms. In the following sections, we describe the particularities of the mechanical design of different types of superconducting accelerator magnets: solenoids, costheta, superferric, and toroids. Special attention is given to the pre-stress principle, which aims to avoid the appearance of tensile stresses in the superconducting coils. A case study on a compact superconducting cyclotron summarizes the main steps and the guidelines that should be followed for a proper mechanical design. Finally, we present some remarks on the measurement techniques.

  3. Method of superconducting joint and its measurement

    International Nuclear Information System (INIS)

    Kim, Woo Gon; Lee, Ho Jin; Hong, Gye Won

    1994-04-01

    The development of joint techniques for superconducting wires is essential to fabricate the high quality superconducting magnet. In this report, the various joining methods and their measuring techniques were reviewed. In order to fabricate a precise superconducting magnet, joining and measuring experiment by using the field decay technique carried out. The contact resistance of coupled specimens with joint was measured as 3.0 x 10 -15 ohm at 1 Tesla which is lower than that of the real operating condition of MRI magnet. It is expected that these data can be used to design and fabricate the superconducting magnets successfully. (Author) 12 refs., 20 figs., 2 tabs

  4. Accelerators and superconductivity: A marriage of convenience

    International Nuclear Information System (INIS)

    Wilson, M.

    1987-01-01

    This lecture deals with the relationship between accelerator technology in high-energy-physics laboratories and the development of superconductors. It concentrates on synchrotron magnets, showing how their special requirements have brought about significant advances in the technology, particularly the development of filamentary superconducting composites. Such developments have made large superconducting accelerators an actuality: the Tevatron in routine operation, the Hadron Electron Ring Accelerator (HERA) under construction, and the Superconducting Super Collider (SSC) and Large Hadron Collider (LHC) at the conceptual design stage. Other applications of superconductivity have also been facilitated - for example medical imaging and small accelerators for industrial and medical use. (orig.)

  5. Foreword: Focus on Superconductivity in Semiconductors

    Directory of Open Access Journals (Sweden)

    Yoshihiko Takano

    2008-01-01

    Full Text Available Since the discovery of superconductivity in diamond, much attention has been given to the issue of superconductivity in semiconductors. Because diamond has a large band gap of 5.5 eV, it is called a wide-gap semiconductor. Upon heavy boron doping over 3×1020 cm−3, diamond becomes metallic and demonstrates superconductivity at temperatures below 11.4 K. This discovery implies that a semiconductor can become a superconductor upon carrier doping. Recently, superconductivity was also discovered in boron-doped silicon and SiC semiconductors. The number of superconducting semiconductors has increased. In 2008 an Fe-based superconductor was discovered in a research project on carrier doping in a LaCuSeO wide-gap semiconductor. This discovery enhanced research activities in the field of superconductivity, where many scientists place particular importance on superconductivity in semiconductors.This focus issue features a variety of topics on superconductivity in semiconductors selected from the 2nd International Workshop on Superconductivity in Diamond and Related Materials (IWSDRM2008, which was held at the National Institute for Materials Science (NIMS, Tsukuba, Japan in July 2008. The 1st workshop was held in 2005 and was published as a special issue in Science and Technology of Advanced Materials (STAM in 2006 (Takano 2006 Sci. Technol. Adv. Mater. 7 S1.The selection of papers describe many important experimental and theoretical studies on superconductivity in semiconductors. Topics on boron-doped diamond include isotope effects (Ekimov et al and the detailed structure of boron sites, and the relation between superconductivity and disorder induced by boron doping. Regarding other semiconductors, the superconducting properties of silicon and SiC (Kriener et al, Muranaka et al and Yanase et al are discussed, and In2O3 (Makise et al is presented as a new superconducting semiconductor. Iron-based superconductors are presented as a new series of high

  6. High Temperature Superconducting Inductor for Antenna Matching

    National Research Council Canada - National Science Library

    Cadotte, R

    1998-01-01

    .... Towards this goal, the U.S. Army Research Laboratory is developing a high critical temperature superconducting spiral inductor and cryogenically cooled amplifier to demonstrate increased sensitivity...

  7. Status of RF superconductivity at Argonne

    International Nuclear Information System (INIS)

    Shepard, K.W.

    1990-01-01

    Development of a superconducting slow-wave structures began at Argonne National Laboratory (ANL) in 1971, and led to the first superconducting heavy-ion linac (ATLAS - the Argonne Tandem-Linac Accelerator System). The Physics Division at ANL has continued to develop superconducting RF technology for accelerating heavy-ions, with the result that the linac has been in an almost continuous process of upgrade and expansion. In 1987, the Engineering Physics Division at ANL began developing of superconducting RF components for the acceleration of high-brightness proton and deuterium beams. The two divisions collaborate in work on several applications of RF superconductivity, and also in work to develop the technology generally. The present report briefly describes major features of the superconducting heavy-ion linac (very-low-velocity superconducting linac, positive ion injector), proton accelerating structures (superconducting resonant cavities for acceleration of high-current proton and deuteron beams, RF properties of oxide superconductors), and future work. Both divisions expect to continue a variety of studies, frequently in collaboration, to advance the basic technology of RF superconductivity. (N.K.)

  8. Flux dynamics in ultrasensitive superconducting focal planes

    Data.gov (United States)

    National Aeronautics and Space Administration — The performance of superconducting focal planes will drive the achievable specifications of ultrasensitive instruments for NASA astrophysics missions, yet they have...

  9. PREFACE: 11th European Conference on Applied Superconductivity (EUCAS2013)

    Science.gov (United States)

    Farinon, Stefania; Pallecchi, Ilaria; Malagoli, Andrea; Lamura, Gianrico

    2014-05-01

    During the 11th edition of the European Conference on Applied Superconductivity, successfully held in Genoa from 15-19 September 2013, more than one thousand participants from over 40 countries were registered and contributions of 7 plenary lectures, 23 invited talks, 203 oral talks and 550 posters were presented. The present issue of Journal of Physics: Conference Series (JPCS) collects the 218 submitted papers that were peer reviewed and accepted in the Conference Proceedings. Similarly to the Superconductor Science and Technology Special issue: ''EUCAS 11th European Conference on Applied Superconductivity'' which contains some plenary and invited contributions, as well as some selected contributions, in this issue the papers are sorted according to the four traditional topics of interest of EUCAS, namely Materials (56 papers), Wires and Tapes (47 papers), Large Scale Applications (64 papers) and Electronics (51 papers). While the it Superconductors Science and Technology special issue focuses on the scientific and technological highlights of the conference, this collection provides an overall view of the worldwide research activity on applied superconductivity, mirroring the main guidelines and the hottest issues, which range from basic studies on newly discovered superconducting compounds to the state-of-the-art advances in large scale applications, wires and tapes fabrication and electronics. We would like to point out that, among the JPCS contributions, six papers present works financed by ongoing EU-Japan projects, three papers belong to the session on junctions and SQUIDs dedicated to the memory of Antonio Barone and one paper belongs to the session on pinning and flux dynamics dedicated to the memory of John Clem. Finally, we would like to thank all the people whose careful work contributed to the preparation of this JPCS issue, in particular the session chairs as well as the peer reviewers. The Editors Stefania Farinon (Editor in Chief, Large Scale

  10. Fluctuation model of organic superconductivity: Internal inconsistencies and contradictory experimental evidence

    International Nuclear Information System (INIS)

    Kwak, J.F.

    1983-01-01

    Internal inconsistencies in the scheme of large superconducting fluctuations, as applied to the superconducting (TMTSF) 2 X compounds (ditetramethyltetraselenafulvalenium salts), are discussed. In particular, it is shown that the assumption of very small interchain coupling is self-contradictory. These materials are actually best regarded as (anisotropic) three-dimensional superconductors. The fluctuation scheme does not provide a consistent interpretation of the data, but is in fact contradicted by many key measurements, including the thermal conductivity, heat capacity, conductivity anisotropy, and critical-field anisotropy

  11. Metal-insulator transitions and superconductivity in ditetramethyltetraselenafulvalenium flourosulfonate [(TMTSF)2FSO3

    International Nuclear Information System (INIS)

    Lacoe, R.C.; Wolf, S.A.; Chaikin, P.M.; Wudl, F.; Aharon-Shalom, E.

    1983-01-01

    We have investigated the phase diagram of the organic charge-transfer salt ditetramethyltetraselenafulvalenium flourosulfonate [(TMTSF) 2 FSO 3 ] which contains an asymmetric dipolar anion. At low pressures there is a metal-insulator transition related to anion ordering. Between 5 and 6 kbar, there is a dipolar glass phase with increased resistivity. However, thermopower and superconducting measurements indicate that the Fermi surface remains ungapped. Above 5 kbar there is a superconducting transition with T/sub c/>2 K. This is the highest T/sub c/ for this family of compounds and suggests that the anions can enhance T/sub c/

  12. Iron-based superconductivity extended to the novel silicide LaFeSiH

    Science.gov (United States)

    Bernardini, F.; Garbarino, G.; Sulpice, A.; Núñez-Regueiro, M.; Gaudin, E.; Chevalier, B.; Méasson, M.-A.; Cano, A.; Tencé, S.

    2018-03-01

    We report the synthesis and characterization of the novel silicide LaFeSiH displaying superconductivity with onset at 11 K. We find that this pnictogen-free compound is isostructural to LaFeAsO, with a similar low-temperature tetragonal to orthorhombic distortion. Using density functional theory we show that this system is also a multiband metal in which the orthorhombic distortion is likely related to single-stripe antiferromagnetic order. Electrical resistivity and magnetic susceptibility measurements reveal that these features occur side by side with superconductivity, which is suppressed by external pressure.

  13. Structural and superconducting properties of as-cast Nb3Al

    International Nuclear Information System (INIS)

    Mondal, Puspen; Manekar, Meghmalhar; Roy, S.B.; Kumar, Ravi; Ganguli, Tapas

    2007-01-01

    We present the results of x-ray diffraction and magnetization measurements on the as-cast compound Nb 3 Al. X-ray diffraction shows the presence of the Al 5 Nb 3 Al phase along with a bcc Nb-Al solid solution. The average grain size of Nb 3 Al estimated from the line broadening is about 35 nm. Magnetization measurements show a superconducting transition temperature of about 16.8 K which is amongst the highest known T c for the as-cast sample. In the superconducting state, the sample shows interesting thermo-magnetic history effects in the temperature and field variation of magnetization. (author)

  14. From superconductivity near a quantum phase transition to superconducting graphite

    Directory of Open Access Journals (Sweden)

    S. S. Saxena

    2006-09-01

    Full Text Available   The collapse of antiferromagnetic order as a function of some quantum tuning parameter such as carrier density or hydrostatic pressure is often accompanied by a region of superconductivity. The corresponding phenomenon in the potentially simpler case of itinerant-electron ferromagnetism, however, remains more illusive. In this paper we consider the reasons why this may be so and summaries evidence suggesting that the obstacles to observing the phenomenon are apparently overcome in a few metallic ferromagnets. A new twist to the problem presented by the recent discoveries in ferroelectric symmetric systems and new graphite intercalate superconductors will also be discussed.

  15. A high field and cryogenic test facility for neutron irradiated superconducting wire

    Science.gov (United States)

    Nishimura, A.; Miyata, H.; Yoshida, M.; Iio, M.; Suzuki, K.; Nakamoto, T.; Yamazaki, M.; Toyama, T.

    2017-12-01

    A 15.5 T superconducting magnet and a variable temperature insert (VTI) system were installed at a radiation control area in Oarai center in Tohoku University to investigate the superconducting properties of activated superconducting materials by fast neutron. The superconductivity was measured at cryogenic temperature and high magnetic field. During these tests, some inconvenient problems were observed and the additional investigation was carried out. The variable temperature insert was designed and assembled to perform the superconducting property tests. without the liquid helium. To remove the heat induced by radiation and joule heating, high purity aluminum rod was used in VTI. The thermal contact was checked by FEM analysis and an additional support was added to confirm the decreasing the stress concentration and the good thermal contact. After the work for improvement, it was affirmed that the test system works well and all troubles were resolved. In this report, the improved technical solution is described and the first data set on the irradiation effect on Nb3Sn wire is presented.

  16. Fine filament NbTi superconductive composite

    International Nuclear Information System (INIS)

    Hong, S.; Grabinsky, G.; Marancik, W.; Pattanayak, D.

    1986-01-01

    The large superconducting magnet for the high energy physics accelerator requires fine filament composite to minimize the field error due to the persistent current in the filaments. New concepts toward the fine filament composite and its cable fabrication are discussed. Two-stage cables of fine wire with intermediate number of filaments were introduced. The first stage was six wires cables around one and in the second stage this was used to produce a Rutherford cable. The advantage of this process is in the ease of billet fabrication since the number of filaments in a single wire is within the range of easy billet fabrication. The disadvantage is in the cable fabrication. One of the major concerns in the fabrication of fine NbTi filaments composite in a copper matrix is the intermetallic compound formation during the extrusion and heat treatment steps. The hard intermetallic particles degrade the uniformity of the filaments and reduce the critical current density. The process of using Nb barrier between the filaments and copper matrix in order to prevent this CuTi intermetallic particle formation is described

  17. Observation of A15 phase transformation in RHQ-Nb3Al wire by neutron diffraction at high-temperature

    International Nuclear Information System (INIS)

    Jin Xinzhe; Nakamoto, Tatsushi; Harjo, Stefanus; Ito, Takayoshi; Ogitsu, Toru; Tsuchiya, Kiyosumi; Yamamoto, Akira; Kikuchi, Akihiro; Takeuchi, Takao; Hemmi, Tsutomu

    2012-01-01

    Highlights: ► A15 phase transition from solid solution occurred within 5 min in RHQ-Nb 3 Al wire. ► The holding duration of 9 h at 800 °C was found to optimize growth of the A15 phase. ► The residual strain in the Nb 3 Al filaments appeared between 200 and 300 °C. ► An isotropic tensile strain of 0.07% was found in the Nb 3 Al at room temperature. ► The tensile effect of the Nb/Ta matrix was dominant in the RHQ-Nb3Al wire. - Abstract: Nb 3 Al superconducting wires produced by rapid heating and quenching (RHQ) method have been developed for application to high field accelerator magnet. In an A15-type superconductor, it is known that residual strain in the superconducting phase induced by thermal contraction after heat treatment influences superconducting properties such as the critical current density. After RHQ treatment, a solid solution of NbAl y with a bcc structure was formed from a jelly-roll of Nb and Al sheets in the wire. To observe the A15 phase transition in the NbAl y and to clarify the mechanism of residual strain generation in the RHQ-Nb 3 Al wire, neutron diffraction measurements were carried out on the J-PARC “TAKUMI” between room-temperature and 800 °C, in which the Nb 3 Al superconducting phase is formed. Here, we report measurements on an RHQ-Nb 3 Al wire with an Nb/Ta composite matrix, using single-peak analysis and multi-peak analysis for peak intensity fitting and peak position fitting, respectively. The phase transition to the A15 was found to occur within a short period about 5 min while the temperature was increasing from 735 to 800 °C. Along the axial direction of the wire, growth of the A15 phase was found to be optimized using a subsequent holding process of 9 h at 800 °C. Following cooling to room temperature, the Nb 3 Al filaments in the wire exhibited an isotropic tensile residual strain of about 0.07%.

  18. Theory of the structural properties of A-15 type materials

    Energy Technology Data Exchange (ETDEWEB)

    Gor' kov, L.P.; Dorokhov, O.N.

    1976-01-01

    The theory of the structural properties of the A-15 compounds is developed starting with a picture of linear chains of atoms of the transition elements. The twofold-degenerate electronic term is shifted and split when interchain transfer is taken into account. A fine structure of the electronic spectrum and the density of states are examined. The latter has two singularities at the Fermi level corresponding to an estimated variation of the composition by several percent. Among the samples showing the martensitic transformation, one of these singularities is supposed to be responsible for the peculiar properties observed, and a theory of the transformation from the cubic to the tetragonal phase is suggested. The temperature dependence of the phonon spectrum has been studied in detail. The theory explains the softening of the phonon modes at large wave vectors in some directions, and predicts features of the phonon spectrum whose observation could be crucial to the theory. 26 references.

  19. First-order superconducting transition in the inter-band model

    Energy Technology Data Exchange (ETDEWEB)

    Gomes da Silva, M. [Universidade Federal do Amazonas, Departamento de Física, 3000, Japiim, 69077-00 Manaus, AM (Brazil); Instituto Federal de Educação Ciência e Tecnologia do Amazonas, Av. 7 de Setembro, 1975 - Centro, Manaus, AM 69020-120 (Brazil); Dinóla Neto, F., E-mail: dinola@ufam.edu.br [Universidade Federal do Amazonas, Departamento de Física, 3000, Japiim, 69077-00 Manaus, AM (Brazil); Padilha, I.T. [Universidade Federal do Amazonas, Departamento de Física, 3000, Japiim, 69077-00 Manaus, AM (Brazil); Ricardo de Sousa, J. [Universidade Federal do Amazonas, Departamento de Física, 3000, Japiim, 69077-00 Manaus, AM (Brazil); National Institute of Science and Technology for Complex Systems, Universidade Federal do Amazonas, 3000, Japiim, 69077-000 Manaus, AM (Brazil); Continentino, M.A. [Centro Brasileiro de Pesquisas Físicas, 22290-180 Rio de Janeiro, RJ (Brazil)

    2014-04-01

    The comprehension about the theoretical features of superconductivity is an interesting and fundamental topic in condensed matter physics. Several theoretical proposals were considered to describe the new classes of superconducting compounds and alloys. In this work we propose to study a non-conventional superconducting system where the Cooper pairs are formed by fermions from different bands described via two band model with hybridization. In this inter-band scenario we find a first-order phase transition at low temperatures and we observe a tricritical point in the phase diagram. In our description, the control parameter is the hybridization that can be tuned by external pressure. This fact indicates the possibility to observe discontinuities in the SC gap amplitude through applying pressure on the system.

  20. Magnetism and Superconductivity in Iron-based Superconductors as Probed by Nuclear Magnetic Resonance

    CERN Document Server

    Hammerath, Franziska

    2012-01-01

    Nuclear Magnetic Resonance (NMR) has been a fundamental player in the studies of superconducting materials for many decades. This local probe technique allows for the study of the static electronic properties as well as of the low energy excitations of the electrons in the normal and the superconducting state. On that account it has also been widely applied to Fe-based superconductors from the very beginning of their discovery in February 2008. This dissertation comprises some of these very first NMR results, reflecting the unconventional nature of superconductivity and its strong link to magnetism in the investigated compounds LaO1–xFxFeAs and LiFeAs.

  1. Progress in heavy-fermion superconductivity. Ce115 and related materials

    International Nuclear Information System (INIS)

    Thompson, Joe D.; Fisk, Zachary

    2012-01-01

    Ce115 and related Ce compounds are particularly suited to detailed studies of the interplay of antiferromagnetic order, unconventional superconductivity and quantum criticality due to their availability as high quality single crystals and their tunability by chemistry, pressure and magnetic field. Neutron-scattering, NMR and angle-resolved thermodynamic measurements have deepened the understanding of this interplay. Very low temperature experiments in pure and lightly doped CeCoIn 5 have elaborated the FFLO-like magnetic state near the field-induced quantum-critical point. New, related superconducting materials have broadened the phase space for discovering underlying principles of heavy-fermion superconductivity and its relationship to nearby states. (author)

  2. Interfacing superconducting qubits and single optical photons

    NARCIS (Netherlands)

    Das, Sumanta; Faez, Sanli; Sørensen, Anders S.

    2016-01-01

    We propose an efficient light-matter interface at optical frequencies between a superconducting qubit and a single photon. The desired interface is based on a hybrid architecture composed of an organic molecule embedded inside an optical waveguide and electrically coupled to a superconducting qubit

  3. Theoretical analyses of superconductivity in iron based ...

    African Journals Online (AJOL)

    This paper focuses on the theoretical analysis of superconductivity in iron based superconductor Ba1−xKxFe2As2. After reviewing the current findings on this system, we suggest that phononexciton combined mechanism gives a right order of superconducting transition temperature (TC) for Ba1−xKxFe2As2 . By developing ...

  4. Josephson plasma resonance in superconducting multilayers

    DEFF Research Database (Denmark)

    Pedersen, Niels Falsig

    1999-01-01

    We derive an analytical solution for the josephson plasma resonance of superconducting multilayers. This analytical solution is derived mainly for low T-c systems with magnetic coupling between the superconducting layers, but many features of our results are more general, and thus an application...... to the recently derived plasma resonance phenomena for high T-c superconductors of the BSCCO type is discussed....

  5. Quasiparticle dynamics in aluminium superconducting microwave resonators

    NARCIS (Netherlands)

    De Visser, P.J.

    2014-01-01

    This thesis describes the intrinsic limits of superconducting microresonator detectors. In a superconductor at low temperature, most of the electrons are paired into so called Cooper pairs, which cause the well-known electrical conduction without resistance. Superconducting microwave resonators have

  6. Superconducting integrated submillimeter receiver for TELIS

    NARCIS (Netherlands)

    Koshelets, Valery P.; Ermakov, Andrey B.; Filippenko, Lyudmila V.; Khudchenko, Andrey V.; Kiselev, Oleg S.; Sobolev, Alexander S.; Torgashin, Mikhail Yu.; Yagoubov, Pavel A.; Hoogeveen, Ruud W. M.; Wild, Wolfgang

    In this report an overview of the results on the development of a single-chip superconducting integrated receiver for the Terahertz Limb Sounder (TELIS) balloon project intended to measure a variety of stratosphere trace gases is presented. The Superconducting Integrated Receiver (SIR) comprises in

  7. Superconducting magnets for energy buncher at FAIR

    International Nuclear Information System (INIS)

    Bhandari, R.K.; Ahammed, M.; Bhattacharya, P.; Bhattacharya, S.; Chattopadhyay, S.; Bhattacharya, T.K.; Bhunia, U.; Chaudhuri, J.; Dey, M.K.; Dutta, A.; DuttaGupta, A.; Mallik, C.; Mandal, B.; Manna, B.; Nandi, C.; Pal, G.; Roy, S.; Saha, S.; Sarma, P.R.

    2011-01-01

    A set of large superconducting magnets have been designed for the Low Energy Buncher (LEB) of the Superconducting Fragment Separator (Super-FRS) for FAIR. The set of magnets will include dipoles and multipoles (sextupole and quadrupole) of stringent quality criteria. Details of design and expected performance have been discussed. (author)

  8. 17th International Conference on RF Superconductivity

    CERN Document Server

    Laxdal, Robert E.; Schaa, Volker R.W.

    2015-01-01

    RF superconductivity is the key technology of accelerators for particle physics, nuclear physics and light sources. SRF 2015 covered the latest advances in the science, technology, and applications of superconducting RF. There was also an industrial exhibit during the conference with the key vendors in the community available to discuss their capabilities and products.

  9. Superconducting linear accelerator system for NSC

    Indian Academy of Sciences (India)

    This paper reports the construction of a superconducting linear accelerator as a booster to the 15 UD Pelletron accelerator at Nuclear Science Centre, New Delhi. The LINAC will use superconducting niobium quarter wave resonators as the accelerating element. Construction of the linear accelerator has progressed ...

  10. Superconducting materials fabrication process and products obtained

    International Nuclear Information System (INIS)

    Dubois, B.; Odier, P.

    1989-01-01

    A fabrication process of a fine superconducting powder easy to sinter is claimed. It consists in thermal treatment of an aerosol containing an organic and/or inorganic salt and/or a hydroxide of a rare earth, an alkaline earth metal and a transition metal in a ratio corresponding to the stoichiometry of the superconducting materials [fr

  11. Theories of superconductivity (a few remarks)

    International Nuclear Information System (INIS)

    Ginzburg, V.L.

    1992-01-01

    The early history in the development of superconductivity. Idea of pairing, Schafroth and BCS types of theories. Some remarks on present state of the microscopical theory of high-temperature superconductors (HTSC). Mean field macroscopic theory of superconductivity and its specific features in HTSC. About generalized macroscopic theory applicable in critical region. Concluding remarks. (orig.)

  12. INTERLAYER OPTICAL CONDUCTIVITY OF A SUPERCONDUCTING BILAYER

    NARCIS (Netherlands)

    GARTSTEIN, YN; RICE, MJ; VANDERMAREL, D

    1994-01-01

    We employ the Bardeen-Cooper-Schrieffer theory to calculate the frequency-dependent interlayer conductivity of a superconducting bilayer, the two layers of which are coupled by weak single-particle tunneling. The effect of the superconducting transition on the normal-state absorption band is to

  13. Superconducting RF activities at Cornell University

    International Nuclear Information System (INIS)

    Kirchgessner, J.; Moffat, D.; Padamsee, H.; Rubin, D.; Sears, J.; Shu, Q.S.

    1990-01-01

    This paper outlines the RF superconductivity research and development work that has taken place at Cornell Laboratory of Nuclear Studies over the past years. The work that has been performed since the last RF superconductivity workshop is emphasized together with a discussion of the direction of future efforts. Past work is summarized first, focusing on research and development activities in the area of RF superconductivity. Superconducting TeV linear collider is then discussed focusing on the application of superconducting RF to a future TeV linear collider. Linear collider structure development is then described centering on the development of a simpler (thereby cheaper) structure for a TeV linear collider. B-factory with superconducting RF is outlined focusing on the formulation of a conceptual design for a B-factory. B-factory structure development is discussed in relation to the advancement in the capability of SC cavities to carry beam currents of several amperes necessary for a high luminosity storage ring. High gradients are discussed as the key to the realization of a high energy superconducting linac or a superconducting RF B-factory. (N.K.)

  14. Voltage distribution within superconducting coils during quench

    International Nuclear Information System (INIS)

    Tominaka, T.; Hara, N.; Kuroda, K.

    1988-01-01

    A computer program which can be applied to the calculation of voltage distribution within superconducting coils during quench has been developed. The calculation is compared with an experiment for a small superconducting solenoid, and the propriety of the calculation is discussed

  15. Diagram of a LEP superconducting cavity

    CERN Multimedia

    1991-01-01

    This diagram gives a schematic representation of the superconducting radio-frequency cavities at LEP. Liquid helium is used to cool the cavity to 4.5 degrees above absolute zero so that very high electric fields can be produced, increasing the operating energy of the accelerator. Superconducting cavities were used only in the LEP-2 phase of the accelerator, from 1996 to 2000.

  16. Superconducting gap anomaly in heavy fermion systems

    Indian Academy of Sciences (India)

    of a pseudo-gap due to superconductivity and the signature of a hybridization gap at the. Fermi level. For the choice of the model parameters, the DOS shows that the HFS is a metal and undergoes a transition to the gap-less superconducting state. Keywords. Heavy fermion superconductor; Narrow band system; Valence ...

  17. Josephson plasma resonance in superconducting multilayers

    DEFF Research Database (Denmark)

    Pedersen, Niels Falsig; Sakai, S

    1998-01-01

    We derive an analytical solution for the Josephson plasma resonance of superconducting multilayers. This analytical solution is derived mainly for low-T-c systems with magnetic coupling between the superconducting layers. but many features of our results are more general, and thus an application...

  18. Josephson plasma resonance in superconducting multilayers

    DEFF Research Database (Denmark)

    Pedersen, Niels Falsig

    1999-01-01

    We derive an analytical solution for the josephson plasma resonance of superconducting multilayers. This analytical solution is derived mainly for low T-c systems with magnetic coupling between the superconducting layers, but many features of our results are more general, and thus an application...

  19. The theory of anyonic superconductivity

    International Nuclear Information System (INIS)

    Lukken, J.D.; Sonnenschien, J.; Weiss, N.

    1991-01-01

    Particles in two spatial dimensions with fractional statistics known, generically, as anyons, have been of interest to particle physicists for nearly ten years. A major change in the direction of research occurred when it was discovered that anyons could play a role as quasiparticles in condensed-matter systems. This was originally discovered to be the case in systems exhibiting the Fractional Quantum Hall Effect. The application of anyons to condensed-matter systems received yet another boost when it was discovered by Laughlin that even an ideal gas of anyons was a superfluid and, as a result, a gas of charged anyons would be a superconductor. This led immediately to attempts to explain the superconductivity of high-T c materials which are layered ceramics in terms of anyons. The main challenge was to find a reasonable model for these materials which has quasiparticles obeying anyonic statistics. The goal of this article is to review the theory of anyonic superconductivity and its possible relation to high-T c materials. The emphasis in this review is on field-theoretical methods. In this paper the authors explain what an anyon is and how it can be modeled mathematically. The authors discuss the possible relationship between anyons and high-T c materials. The authors review several of the attempts to obtain anyonic quasiparticles from the Hubbard model which is commonly used to describe these materials. The authors describe the mathematical modeling of anyons in terms of their interaction with an Abelian gauge field with a Chern-Simons term. This description of anyons is used extensively in this article. The authors discuss the possible criteria for superconductivity in anyonic systems with particular emphasis on criteria which would be useful in the Chern-Simons description

  20. Quantum acoustics with superconducting qubits

    Science.gov (United States)

    Chu, Yiwen

    2017-04-01

    The ability to engineer and manipulate different types of quantum mechanical objects allows us to take advantage of their unique properties and create useful hybrid technologies. Thus far, complex quantum states and exquisite quantum control have been demonstrated in systems ranging from trapped ions to superconducting resonators. Recently, there have been many efforts to extend these demonstrations to the motion of complex, macroscopic objects. These mechanical objects have important applications as quantum memories or transducers for measuring and connecting different types of quantum systems. In particular, there have been a few experiments that couple motion to nonlinear quantum objects such as superconducting qubits. This opens up the possibility of creating, storing, and manipulating non-Gaussian quantum states in mechanical degrees of freedom. However, before sophisticated quantum control of mechanical motion can be achieved, we must realize systems with long coherence times while maintaining a sufficient interaction strength. These systems should be implemented in a simple and robust manner that allows for increasing complexity and scalability in the future. In this talk, I will describe our recent experiments demonstrating a high frequency bulk acoustic wave resonator that is strongly coupled to a superconducting qubit using piezoelectric transduction. In contrast to previous experiments with qubit-mechanical systems, our device requires only simple fabrication methods, extends coherence times to many microseconds, and provides controllable access to a multitude of phonon modes. We use this system to demonstrate basic quantum operations on the coupled qubit-phonon system. Straightforward improvements to the current device will allow for advanced protocols analogous to what has been shown in optical and microwave resonators, resulting in a novel resource for implementing hybrid quantum technologies.

  1. Effect of nonmagnetic defects on superconducting and transport properties of Ba(Fe1- x Co x As)2 high- T c superconductors

    Science.gov (United States)

    Blokhin, I. S.; Gavrilkin, S. Yu.; Gorshunov, B. P.; Dravin, V. A.; Zhukova, E. S.; Ivanenko, O. M.; Aida, K.; Krasnosvobodtsev, S. I.; Kurt, F.; Mitsen, K. V.; Tsvetkov, A. Yu.

    2015-11-01

    The effect of nonmagnetic defects on superconducting and transport properties of Ba(Fe0.94Co0.06As)2 films is studied for obtaining information on the symmetry type of the order parameter for superconducting pnictides. Such defects are generated in the film by irradiation by He+ ions with an energy of 200 keV. It is found that a decrease in superconducting transition temperature T c upon an increase in the concentration of nonmagnetic defects in this compound occurs much more slowly than predicted in the model assuming s ±-wave symmetry of the order parameter. Joint analysis of the influence of nonmagnetic defects on the superconducting and magnetotransport properties of such films leads to the conclusion that superconductivity is completely suppressed in them after critical disorder is attained, which assumes the s ++-wave symmetry.

  2. Terahertz superconducting plasmonic hole array.

    Science.gov (United States)

    Tian, Zhen; Singh, Ranjan; Han, Jiaguang; Gu, Jianqiang; Xing, Qirong; Wu, Judy; Zhang, Weili

    2010-11-01

    We demonstrate a superconductor array of subwavelength holes with active thermal control over the resonant transmission induced by surface plasmon polaritons. The array was lithographically fabricated on a high-temperature yttrium barium copper oxide superconductor and characterized by terahertz time-domain spectroscopy. We observe a clear transition from a virtual excitation of the surface plasmon mode to a real surface plasmon mode. The highly controllable superconducting plasmonic crystals may find promising applications in the design of low-loss, large- dynamic-range amplitude modulation and surface-plasmon-based terahertz devices.

  3. Superconducting heavy-ion linacs

    International Nuclear Information System (INIS)

    Bollinger, L.M.

    1977-01-01

    A summary is given of plans developed by four different groups for the construction of small superconducting linacs to boost the energy of heavy ions from existing tandem electrostatic accelerators. The projects considered are the linac under construction at Argonne and the design efforts at Karlsruhe, at Stanford, and by a Cal Tech-Stony Brook collaboration. The intended uses of the accelerator systems are stated. Beam dynamics of linacs formed of short independently-phased resonators are reviewed, and the implications for performance are discussed. The main parameters of the four linacs are compared, and a brief analysis of accelerating structures is given

  4. Superconducting magnets for isochronous cyclotrons

    International Nuclear Information System (INIS)

    Martin, E.R.

    1979-01-01

    Different approaches using superconductivity for isochronous cyclotrons and examination of advantages and disadvantages of each of them are considered. The discussion is focused on isochronous cyclotrons designed for heavy particle acceleration up to kinetic energies of approximately 0.5 times the rest energy of the accelerated ion. A quantitative solution for the influence of the field edges and for the various values of the valley fields are given. The Indiana University cyclotron is considered where both the coil and the associated pole tip material operate at a cryogenic temperature. Offered are advantages for the design which provide reduction in size and impivement in terms of beam dynamics

  5. Superconductivity a very short introduction

    CERN Document Server

    Blundell, Stephen

    2009-01-01

    Superconductivity is one of the most exciting areas of research in physics today. Outlining the history of its discovery, and the race to understand its many mysterious and counter-intuitive phenomena, this Very Short Introduction explains in accessible terms the theories that have been developed, and how they have influenced other areas of science, including the Higgs boson of particle physics and ideas about the early Universe. It is an engaging and informative accountof a fascinating scientific detective story, and an intelligible insight into some deep and beautiful ideas of physics

  6. Superconducting proton ring for PETRA

    International Nuclear Information System (INIS)

    Baynham, E.

    1979-01-01

    A powerful new facility for colliding beam physics could be provided by adding a proton storage ring in the range of several hundred GeV to the electron-positron storage ring PETRA at DESY. This can be achieved in an economic way utilizing the PETRA tunnel and taking advantage of the higher magnetic fields of superconducting magnets which would be placed above or below the PETRA magnets. A central field of 4 Tesla in the bending magnets corresponds to a proton energy of 225 GeV. (orig.)

  7. Review of superconducting ion linacs

    International Nuclear Information System (INIS)

    Bollinger, L.M.

    1992-01-01

    This paper summarizes the status of the technology of superconducting (SC) linacs designed for the acceleration of ions. The emphasis is on the technical issues involved, with only brief descriptions of the numerous linacs now in operation or under construction. Recent developments of special interest are treated in more detail, and remaining technical challenges are outlined. The technology required for the acceleration of ions with velocity β=1 is not discussed because it is almost the same as for relativistic electrons. That is, this paper is mainly about SC linacs for low-velocity heavy ions

  8. Superconducting three element synchronous ac machine

    International Nuclear Information System (INIS)

    Boyer, L.; Chabrerie, J.P.; Mailfert, A.; Renard, M.

    1975-01-01

    There is a growing interest in ac superconducting machines. Of several new concepts proposed for these machines in the last years one of the most promising seems to be the ''three elements'' concept which allows the cancellation of the torque acting on the superconducting field winding, thus overcoming some of the major contraints. This concept leads to a device of induction-type generator. A synchronous, three element superconducting ac machine is described, in which a room temperature, dc fed rotating winding is inserted between the superconducting field winding and the ac armature. The steady-state machine theory is developed, the flux linkages are established, and the torque expressions are derived. The condition for zero torque on the field winding, as well as the resulting electrical equations of the machine, are given. The theoretical behavior of the machine is studied, using phasor diagrams and assuming for the superconducting field winding either a constant current or a constant flux condition

  9. RF superconductivity for accelerators. 2. ed.

    Energy Technology Data Exchange (ETDEWEB)

    Padamsee, H. [Cornell Univ., Ithaca, NY (United States). Lab. of Nuclear Studies; Knobloch, J. [BESSY GmbH, Berlin (Germany); Hays, T. [Cosmic Consulting, Gore, VA (United States)

    2008-07-01

    This book introduces some of the key ideas of RF Superconductivity by using a pedagogic approach, and presents a comprehensive overview of the field. It is divided into four parts. The first part introduces the basic concepts of microwave cavities for particle acceleration. The second part is devoted to the observed behavior of superconducting cavities. In the third part, general issues connected with beam-cavity interaction and related issues for critical components are covered. The final part discusses applications of superconducting cavities to frontier accelerators of the future, drawing heavily on examples that are in their most advanced stage. Each part of the book ends in a problems section to illustrate and amplify text material as well as to draw on example applications of superconducting cavities to existing and future accelerators. From the Contents: - Basics - Performance of Superconducting Cavities - Couplers and Tuners - Frontier Accelerators. (orig.)

  10. Superconductivity in compensated and uncompensated semiconductors.

    Science.gov (United States)

    Yanase, Youichi; Yorozu, Naoyuki

    2008-12-01

    We investigate the localization and superconductivity in heavily doped semiconductors. The crossover from the superconductivity in the host band to that in the impurity band is described on the basis of the disordered three-dimensional attractive Hubbard model for binary alloys. The microscopic inhomogeneity and the thermal superconducting fluctuation are taken into account using the self-consistent 1-loop order theory. The superconductor-insulator transition accompanies the crossover from the host band to the impurity band. We point out an enhancement of the critical temperature T c around the crossover. Further localization of electron wave functions leads to the localization of Cooper pairs and induces the pseudogap. We find that both the doping compensation by additional donors and the carrier increase by additional acceptors suppress the superconductivity. A theoretical interpretation is proposed for the superconductivity in the boron-doped diamond, SiC, and Si.

  11. Superconductivity in compensated and uncompensated semiconductors

    Directory of Open Access Journals (Sweden)

    Youichi Yanase and Naoyuki Yorozu

    2008-01-01

    Full Text Available We investigate the localization and superconductivity in heavily doped semiconductors. The crossover from the superconductivity in the host band to that in the impurity band is described on the basis of the disordered three-dimensional attractive Hubbard model for binary alloys. The microscopic inhomogeneity and the thermal superconducting fluctuation are taken into account using the self-consistent 1-loop order theory. The superconductor-insulator transition accompanies the crossover from the host band to the impurity band. We point out an enhancement of the critical temperature Tc around the crossover. Further localization of electron wave functions leads to the localization of Cooper pairs and induces the pseudogap. We find that both the doping compensation by additional donors and the carrier increase by additional acceptors suppress the superconductivity. A theoretical interpretation is proposed for the superconductivity in the boron-doped diamond, SiC, and Si.

  12. Towards Light Sources Featuring Superconducting Miniundulators

    Science.gov (United States)

    Moser, H. O.; Diao, C. Z.

    Besides the exploitation of the Helios 2 superconducting compact storage ring for user operations and for its own R&D work, SSLS envisions a 4th generation synchrotron light source to complement and, eventually, replace the current facility. This vision includes an accelerator system based on a superconducting linear accelerator with up to 5 recirculation loops for energy multiplication and recovery with the distinguishing feature that the light would be generated by superconducting mini- and micro-undulators. Under this programme, SSLS is pursuing the development of superconducting miniundulators including a proof-of-technology electron beam experiment in co-operation with the Shanghai Institute of Applied Physics and the analytical and numerical study of the fabrication tolerances of superconducting miniundulators with respect to their finite length field errors and mechanical errors.

  13. Magnetic imaging of antiferromagnetic and superconducting phases in R bxF e2 -yS e2 crystals

    Science.gov (United States)

    Hazi, J.; Mousavi, T.; Dudin, P.; van der Laan, G.; Maccherozzi, F.; Krzton-Maziopa, A.; Pomjakushina, E.; Conder, K.; Speller, S. C.

    2018-02-01

    High-temperature superconducting (HTS) cuprate materials, with the ability to carry large electrical currents with no resistance at easily reachable temperatures, have stimulated enormous scientific and industrial interest since their discovery in the 1980's. However, technological applications of these promising compounds have been limited by their chemical and microstructural complexity and the challenging processing strategies required for the exploitation of their extraordinary properties. The lack of theoretical understanding of the mechanism for superconductivity in these HTS materials has also hindered the search for new superconducting systems with enhanced performance. The unexpected discovery in 2008 of HTS iron-based compounds has provided an entirely new family of materials for studying the crucial interplay between superconductivity and magnetism in unconventional superconductors. Alkali-metal-doped iron selenide (AxF e2 -yS e2 , A =alkali metal ) compounds are of particular interest owing to the coexistence of superconductivity at relatively high temperatures with antiferromagnetism. Intrinsic phase separation on the mesoscopic scale is also known to occur in what were intended to be single crystals of these compounds, making it difficult to interpret bulk property measurements. Here, we use a combination of two advanced microscopy techniques to provide direct evidence of the magnetic properties of the individual phases. First, x-ray linear dichroism studies in a photoelectron emission microscope, and supporting multiplet calculations, indicate that the matrix (majority) phase is antiferromagnetic whereas the minority phase is nonmagnetic at room temperature. Second, cryogenic magnetic force microscopy demonstrates unambiguously that superconductivity occurs only in the minority phase. The correlation of these findings with previous microstructural studies and bulk measurements paves the way for understanding the intriguing electronic and magnetic

  14. Tuning the band structure and superconductivity in single-layer FeSe by interface engineering.

    Science.gov (United States)

    Peng, R; Xu, H C; Tan, S Y; Cao, H Y; Xia, M; Shen, X P; Huang, Z C; Wen, C H P; Song, Q; Zhang, T; Xie, B P; Gong, X G; Feng, D L

    2014-09-26

    The interface between transition metal compounds provides a rich playground for emergent phenomena. Recently, significantly enhanced superconductivity has been reported for single-layer FeSe on Nb-doped SrTiO3 substrate. Yet it remains mysterious how the interface affects the superconductivity. Here we use in situ angle-resolved photoemission spectroscopy to investigate various FeSe-based heterostructures grown by molecular beam epitaxy, and uncover that electronic correlations and superconducting gap-closing temperature (Tg) are tuned by interfacial effects. Tg up to 75 K is observed in extremely tensile-strained single-layer FeSe on Nb-doped BaTiO3, which sets a record high pairing temperature for both Fe-based superconductor and monolayer-thick films, providing a promising prospect on realizing more cost-effective superconducting device. Moreover, our results exclude the direct correlation between superconductivity and tensile strain or the energy of an interfacial phonon mode, and highlight the critical and non-trivial role of FeSe/oxide interface on the high Tg, which provides new clues for understanding its origin.

  15. Colloquium: High pressure and road to room temperature superconductivity

    Science.gov (United States)

    Gor'kov, Lev P.; Kresin, Vladimir Z.

    2018-01-01

    This Colloquium is concerned with the superconducting state of new high-Tc compounds containing hydrogen ions (hydrides). Recently superconductivity with the record-setting transition temperature of Tc=203 K was reported for sulfur hydrides under high pressure. In general, high pressure serves as a path finding tool toward novel structures, including those with very high Tc . The field has a rich and interesting history. Currently, it is broadly recognized that superconductivity in sulfur hydrides owes its origin to the phonon mechanism. However, the picture differs from the conventional one in important ways. The phonon spectrum in sulfur hydride is both broad and has a complex structure. Superconductivity arises mainly due to strong coupling to the high-frequency optical modes, although the acoustic phonons also make a noticeable contribution. A new approach is described, which generalizes the standard treatment of the phonon mechanism and makes it possible to obtain an analytical expression for Tc in this phase. It turns out that, unlike in the conventional case, the value of the isotope coefficient (for the deuterium-hydrogen substitution) varies with the pressure and reflects the impact of the optical modes. The phase diagram, that is the pressure dependence of Tc , is rather peculiar. A crucial feature is that increasing pressure results in a series of structural transitions, including the one which yields the superconducting phase with the record Tc of 203 K. In a narrow region near P ≈150 GPa the critical temperature rises sharply from Tc≈120 to ≈200 K . It seems that the sharp structural transition, which produces the high-Tc phase, is a first-order phase transition caused by interaction between the order parameter and lattice deformations. A remarkable feature of the electronic spectrum in the high-Tc phase is the appearance of small pockets at the Fermi level. Their presence leads to a two-gap spectrum, which can, in principle, be observed with the

  16. Transition metal borides. Synthesis, characterization and superconducting properties

    International Nuclear Information System (INIS)

    Kayhan, Mehmet

    2013-01-01

    A systematic study was done on the synthesis and superconducting properties of metal rich transition metal borides. Five different binary systems were investigated including the boride systems of niobium, tantalum, molybdenum, tungsten and rhenium. High temperature solid state methods were used in order to synthesize samples of different transition metal borides of the composition M 2 B, MB, M 3 B 2 , MB 2 , and M 2 B 4 . The reactions were carried out in three different furnaces with different sample containers: the electric arc (copper crucible), the high frequency induction furnace (boron nitride, tantalum or glassy carbon crucibles), and the conventional tube furnace (sealed evacuated quartz ampoules). The products obtained were characterized with X-ray powder diffractometry, scanning electron microscopy and energy-dispersive X-ray spectroscopy. Phase analyses and crystal structure refinements using the Rietveld method and based on structure models known from literature were performed. A neutron diffraction measurement was done for W 2 B 4 to allow for a complete crystal structure determination, because of the presence of a heavy element like tungsten and a light element like boron that made it difficult to determine the accurate determination of the boron atom positions and occupancies from X-ray data. A new structure model for W 2 B 4 was proposed. Magnetic measurements in a SQUID magnetometer down to temperatures as low as 1.8 K were performed to several of the products in order to see if the transition metal borides become superconducting at low temperatures, and the results were compared with data from literature. Superconducting properties were found for the following compounds: NbB 2 (T C = 3.5 K), β-MoB (T C = 2.4 K), β-WB (T C = 2.0 K), α-WB (T C = 4.3 K), W 2 B 4 (T C = 5.4 K), Re 7 B 3 (T C = 2.4 K). A relationship between the superconducting properties and the compositional and structural features was discussed for metal diborides. Also it was

  17. Superconducting coil and method of stress management in a superconducting coil

    Science.gov (United States)

    McIntyre, Peter M.; Shen, Weijun; Diaczenko, Nick; Gross, Dan A.

    1999-01-01

    A superconducting coil (12) having a plurality of superconducting layers (18) is provided. Each superconducting layer (18) may have at least one superconducting element (20) which produces an operational load. An outer support structure (24) may be disposed outwardly from the plurality of layers (18). A load transfer system (22) may be coupled between at least one of the superconducting elements (20) and the outer support structure (24). The load transfer system (22) may include a support matrix structure (30) operable to transfer the operational load from the superconducting element (20) directly to the outer support structure (24). A shear release layer (40) may be disposed, in part, between the superconducting element (20) and the support matrix structure (30) for relieving a shear stress between the superconducting element (20) and the support matrix structure (30). A compliant layer (42) may also be disposed, in part, between the superconducting element (20) and the support matrix structure (30) for relieving a compressive stress on the superconducting element (20).

  18. Superconducting superconvulsion. Shock US decision

    International Nuclear Information System (INIS)

    Anon.

    1993-01-01

    After a baffling succession of seesaw decisions which saw the mood swing from the depths of pessimism to supreme optimism and back, on 21 October a US House of Representatives Committee proposed $640 million for the 'orderly termination' of the Superconducting Supercollider (SSC) project in Ellis County, Texas. By next July, the US Secretary of Energy is requested to produce a plan to 'maximize the value of the investment in the project and minimizing the loss to the US, including recommendations as to the feasibility of utilizing SSC assets in whole or in part in pursuit of an international high energy physics endeavour.' The SSC was to have been the biggest of them all - two 87-kilometre rings of superconducting magnets to collide proton beams at a total energy of 40 TeV (40,000 GeV) and search for the mechanisms underlying the behaviour of the quark constituents deep inside the colliding particles. It was from the start an ambitious project. It was meant to be. Conceived in the early 1980s amid all the Reagan euphoria of 'junk' bonds and heavy government borrowing, the SSC idea was in some ways a scientific parallel for the audacious technology of the Strategic Defense Initiative - 'Star Wars'

  19. Three-flavor color superconductivity

    Energy Technology Data Exchange (ETDEWEB)

    Malekzadeh, H.

    2007-12-15

    I investigate some of the inert phases in three-flavor, spin-zero color-superconducting quark matter: the CFL phase (the analogue of the B phase in superfluid {sup 3}He), the A and A{sup *} phases, and the 2SC and sSC phases. I compute the pressure of these phases with and without the neutrality condition. Without the neutrality condition, after the CFL phase the sSC phase is the dominant phase. However, including the neutrality condition, the CFL phase is again the energetically favored phase except for a small region of intermediate densities where the 2SC/A{sup *} phase is favored. It is shown that the 2SC phase is identical to the A{sup *} phase up to a color rotation. In addition, I calculate the self-energies and the spectral densities of longitudinal and transverse gluons at zero temperature in color-superconducting quark matter in the CFL phase. I find a collective excitation, a plasmon, at energies smaller than two times the gap parameter and momenta smaller than about eight times the gap. The dispersion relation of this mode exhibits a minimum at some nonzero value of momentum, indicating a van Hove singularity. (orig.)

  20. The superconducting kaon spectrometer - SKS

    International Nuclear Information System (INIS)

    Fukuda, T.; Takahashi, T.; Aoki, K.; Doi, Y.; Kondo, Y.; Makida, Y.; Nomachi, M.; Noumi, H.; Sasaki, O.; Shintomi, T.; Bhang, H.; Park, H.; Youn, M.; Yu, H.; Gavrilov, Y.; Ajimura, S.; Kishimoto, T.; Ohkusu, A.; Shinkai, N.; Maeda, K.; Sawafta, R.

    1995-01-01

    A superconducting kaon spectrometer has been installed in the north experimental hall of the KEK 12-GeV proton synchrotron. The spectrometer was designed to serve for nuclear physics experiments with meson beams in the 1 GeV/c region, particular emphasis being laid on study of Λ-hypernuclei via (π + ,K + ) reactions. In order to obtain Λ-hypernuclear data with better statistics and energy resolution, it was designed to have a good momentum resolution of 0.1% FWHM and a large acceptance of 100 msr. It consists of a large superconducting dipole magnet, tracking chambers, and trigger counters that can efficiently select kaons from large background of pions and protons. The overall energy resolution for scattering is realized together with a beam-line spectrometer in the K6 beam line, the momentum resolution of which was also designed to be better than 0.1% FWHM. A good energy resolution of better than 2 MeV FWHM has been confirmed in π - - 12 C elastic scattering and in the (π + ,K + ) reaction on 12 C. (orig.)

  1. Characterization of superconducting multilayers samples

    CERN Document Server

    Antoine, C Z; Berry, S; Bouat, S; Jacquot, J F; Villegier, J C; Lamura, G; Gurevich, A

    2009-01-01

    Best RF bulk niobium accelerating cavities have nearly reached their ultimate limits at rf equatorial magnetic field H  200 mT close to the thermodynamic critical field Hc. In 2006 Gurevich proposed to use nanoscale layers of superconducting materials with high values of Hc > HcNb for magnetic shielding of bulk niobium to increase the breakdown magnetic field inside SC RF cavities [1]. Depositing good quality layers inside a whole cavity is rather difficult but we have sputtered high quality samples by applying the technique used for the preparation of superconducting electronics circuits and characterized these samples by X-ray reflectivity, dc resistivity (PPMS) and dc magnetization (SQUID). Dc magnetization curves of a 250 nm thick Nb film have been measured, with and without a magnetron sputtered coating of a single or multiple stack of 15 nm MgO and 25 nm NbN layers. The Nb samples with/without the coating clearly exhibit different behaviors. Because SQUID measurements are influenced by edge an...

  2. High Temperature Superconducting Underground Cable

    International Nuclear Information System (INIS)

    Farrell, Roger A.

    2010-01-01

    The purpose of this Project was to design, build, install and demonstrate the technical feasibility of an underground high temperature superconducting (HTS) power cable installed between two utility substations. In the first phase two HTS cables, 320 m and 30 m in length, were constructed using 1st generation BSCCO wire. The two 34.5 kV, 800 Arms, 48 MVA sections were connected together using a superconducting joint in an underground vault. In the second phase the 30 m BSCCO cable was replaced by one constructed with 2nd generation YBCO wire. 2nd generation wire is needed for commercialization because of inherent cost and performance benefits. Primary objectives of the Project were to build and operate an HTS cable system which demonstrates significant progress towards commercial progress and addresses real world utility concerns such as installation, maintenance, reliability and compatibility with the existing grid. Four key technical areas addressed were the HTS cable and terminations (where the cable connects to the grid), cryogenic refrigeration system, underground cable-to-cable joint (needed for replacement of cable sections) and cost-effective 2nd generation HTS wire. This was the worlds first installation and operation of an HTS cable underground, between two utility substations as well as the first to demonstrate a cable-to-cable joint, remote monitoring system and 2nd generation HTS.

  3. Superconducting rf development at ATLAS

    Energy Technology Data Exchange (ETDEWEB)

    Shepard, K.W.; Kedzie, M.; Clifft, B.E. [Argonne National Lab., IL (United States); Roy, A.; Potukuchi, P. [Nuclear Science Centre, New Delhi (India); Givens, J.; Potter, J.; Crandall, K. [AccSys Technology, Inc., Pleasanton, CA (United States); Added, N. [Sao Paulo Univ., SP (Brazil)

    1993-12-31

    The ATLAS superconducting heavy-ion linac began operation in 1978 and has operated nearly continuously since that time, while undergoing a series of upgrades and expansions, the most recent being the ``uranium upgrade`` completed earlier this year and described below. In its present configuration the ATLAS linac consists of an array of 64 resonant cavities operating from 48 to 145 MHz, which match a range of particle velocities .007 < {beta} = v/c < .2. The linac provides approximately 50 MV of effective accelerating potential for ions of q/m > 1/10 over the entire periodic table. Delivered beams include 5 {minus} 7 pnA of {sup 238}U{sup 39+} at 1535 MeV. At present more than 10{sup 6} cavity-hours of operation at surface electric fields of 15 MV/m have been accumulated. Superconducting structure development at ATLAS is aimed at improving the cost/performance of existing low velocity structures both for possible future ATLAS upgrades, and also for heavy-ion linacs at other institutions. An application of particular current interest is to develop structures suitable for accelerating radioactive ion beams. Such structures must accelerate very low charge to mass ratio beams and must also have very large transverse acceptance.

  4. Three-flavor color superconductivity

    International Nuclear Information System (INIS)

    Malekzadeh, H.

    2007-12-01

    I investigate some of the inert phases in three-flavor, spin-zero color-superconducting quark matter: the CFL phase (the analogue of the B phase in superfluid 3 He), the A and A * phases, and the 2SC and sSC phases. I compute the pressure of these phases with and without the neutrality condition. Without the neutrality condition, after the CFL phase the sSC phase is the dominant phase. However, including the neutrality condition, the CFL phase is again the energetically favored phase except for a small region of intermediate densities where the 2SC/A * phase is favored. It is shown that the 2SC phase is identical to the A * phase up to a color rotation. In addition, I calculate the self-energies and the spectral densities of longitudinal and transverse gluons at zero temperature in color-superconducting quark matter in the CFL phase. I find a collective excitation, a plasmon, at energies smaller than two times the gap parameter and momenta smaller than about eight times the gap. The dispersion relation of this mode exhibits a minimum at some nonzero value of momentum, indicating a van Hove singularity. (orig.)

  5. High Temperature Superconducting Underground Cable

    Energy Technology Data Exchange (ETDEWEB)

    Farrell, Roger, A.

    2010-02-28

    The purpose of this Project was to design, build, install and demonstrate the technical feasibility of an underground high temperature superconducting (HTS) power cable installed between two utility substations. In the first phase two HTS cables, 320 m and 30 m in length, were constructed using 1st generation BSCCO wire. The two 34.5 kV, 800 Arms, 48 MVA sections were connected together using a superconducting joint in an underground vault. In the second phase the 30 m BSCCO cable was replaced by one constructed with 2nd generation YBCO wire. 2nd generation wire is needed for commercialization because of inherent cost and performance benefits. Primary objectives of the Project were to build and operate an HTS cable system which demonstrates significant progress towards commercial progress and addresses real world utility concerns such as installation, maintenance, reliability and compatibility with the existing grid. Four key technical areas addressed were the HTS cable and terminations (where the cable connects to the grid), cryogenic refrigeration system, underground cable-to-cable joint (needed for replacement of cable sections) and cost-effective 2nd generation HTS wire. This was the world’s first installation and operation of an HTS cable underground, between two utility substations as well as the first to demonstrate a cable-to-cable joint, remote monitoring system and 2nd generation HTS.

  6. The LHC Superconducting RF System

    CERN Document Server

    Boussard, Daniel

    1999-01-01

    The European Laboratory for Particle Physics (CERN), the largest high energy physics laboratory worldwide, is constructing the Large Hadron Collider (LHC) in the existing 27 km circumference LEP (Large Electron Positron) collider tunnel. For the LHC, superconducting cavities, operating at 4.5 K, will provide the required acceleration field for ramping the beam energy up to 7 TeV and for keeping the colliding proton beams tightly bunched. Superconducting cavities were chosen, not only because of their high acceleration field leading to a small contribution to the machine impedance, but also because of their high stored energy which minimises the effects of periodic transient beam loading associated with the high beam intensity (0.5 A). There will be eight single-cell cavities per beam, each delivering 2 MV (5.3 MV/m) at 400 MHz. The cavities themselves are now being manufactured by industrial firms, using niobium on copper technology which gives full satisfaction at LEP. A complete cavity prototype assembly in...

  7. Large superconducting wind turbine generators

    DEFF Research Database (Denmark)

    Abrahamsen, Asger Bech; Magnusson, Niklas; Jensen, Bogi Bech

    2012-01-01

    and the rotation speed is lowered in order to limit the tip speed of the blades. The ability of superconducting materials to carry high current densities with very small losses might facilitate a new class of generators operating with an air gap flux density considerably higher than conventional generators...... and thereby having a smaller size and weight [1, 2]. A 5 MW superconducting wind turbine generator forms the basics for the feasibility considerations, particularly for the YBCO and MgB2 superconductors entering the commercial market. Initial results indicate that a 5 MW generator with an active weight of 34...... tons, diameter of 4.2 m and length of 1.2 m can be realized using superconductors carrying 300 A/mm2 in a magnetic field of 4 T and an air gap flux density of the order 2.5 T. The results are compared to the performance of available superconductors, as well as the near future forecasted performance....

  8. Inelastic neutron study in superconductivity YBa2(Cu1-xCox)3O7

    International Nuclear Information System (INIS)

    Bellouard, C.; Hennion, M.; Mirebeau, I.; Dianoux, A.J.; Caignaert, V.

    1991-01-01

    We have performed an inelastic neutron study in superconducting YBa 2 (Cu 1-x Co x ) 3 O 7 , x=0.06, T c =60K. At room temperature, the magnetic moment value M ≅3μ B is close to the value determined by susceptibility measurements (3.4 μ B ). With decreasing temperature and approaching the superconducting transition, the magnetic intensity shows an anomalous increase. Finally, a spin glass like freezing is observed below a very high temperature (T g =50K). These results are compared with those obtained in Fe-doped compounds and in Co-doped non superconducting compounds. YBa 2 (Cu 1-x Co x ) 3 O 7 has been widely studied by susceptibility measurements, X-ray and neutron diffraction. Like the Fe substitution, Co doping induces a decrease of T c which vanishes for x>0.14 and an orthorhombic to tetragonal transition for x>0.3 [1]. We report here an inelastic neutron study of a superconducting sample with x=0.06. For this concentration. Co is found to occupy only the Cu 1 site [2]. This differs from the Fe case where Moessbauer experiments have shown that 10% of the Fe atoms substitute on the Cu 2 site [3]. 7 refs.; 2 figs

  9. Sample of superconducting wiring (Niobium Titanium)

    CERN Multimedia

    About NbTi cable: The cable consists of 36 strands of superconducting wire, each strand has a diameter of 0.825 mm and houses 6300 superconducting filaments of niobium-titanium (Nb-Ti, a superconducting alloy). Each filament has a diameter of about 0.006 mm, i.e. 10 times smaller than a typical human hair. The filaments are embedded in a high-purity copper matrix. Copper is a normal conducting material. The filaments are in the superconductive state when the temperature is below about -263ºC (10.15 K). When the filaments leave the superconductive state, the copper acts as conductor transports the electrical current. Each strand of The NbTi cable (at superconducting state) has a current density of up to above 2000 A/mm2 at 9 T and -271ºC (2.15 K). A cable transport a current of about 13000 A at 10 T and -271ºC (2.15 K). About LHC superconducting wiring: The high magnetic fields needed for the LHC can only be reached using superconductors. At very low temperatures, superconductors have no electrical resista...

  10. Sample of superconducting wiring (Niobium Titanium)

    CERN Multimedia

    About NbTi cable: The cable consists of 36 strands of superconducting wire, each strand has a diameter of 0.825 mm and houses 6300 superconducting filaments of niobium-titanium (Nb-Ti, a superconducting alloy). Each filament has a diameter of about 0.006 mm, i.e. 10 times smaller than a typical human hair. The filaments are embedded in a high-purity copper matrix. Copper is a normal conducting material. The filaments are in the superconductive state when the temperature is below about -263ºC (10.15 K). When the filaments leave the superconductive state, the copper acts as conductor transports the electrical current. Each strand of The NbTi cable (at superconducting state) has a current density of up to above 2000 A/mm2 at 9 T and -271ºC (2.15 K). A cable transport a current of about 13000 A at 10 T and -271ºC (2.15 K). About LHC superconducting wiring: The high magnetic fields needed for the LHC can only be reached using superconductors. At very low temperatures, superconductors have no electrical resistan...

  11. Pressure Effect on Superconductivity of Rhenium

    Science.gov (United States)

    Takahama, Kazushi; Matsuoka, Takahiro; Shimizu, Katsuya

    2013-06-01

    Rhenium metal is often used as a gasket material in high pressure experiments using DACs. It has been known that Re become a superconductor with superconducting transition temperature Tc of 1.6-2.8 K at ambient pressure. Although, pressure dependence of Tc, have not been studied in detail over 2 GPa. It's important to study pressure effect on Tc of Re in two points. First is that hard simple elements Os, W, Ir and Re are known to superconduct with very low Tcs at ambient pressure, but high pressure properties of their Tc have not been well studies so far. Another point is a technical aspect. In the studies of superconductivity under high pressures, we employ electrical resistance and magnetic susceptibility measurements to detect superconductivity. Superconducting Re-gasket below 4 K masks superconducting signal of sample in magnetic susceptibility measurements. In electrical resistance measurements, if the electric circuit has a short with Re-gasket, superconducting transition comes to be mixed in measured data. We present pressure dependence of Tc of rhenium up to 65 GPa measured using a DAC. We observed Tc increases in pressure range of 0-10 GPa and it gradually decreased with applied pressure.

  12. Superconductivity Engineering and Its Application for Fusion 3.Superconducting Technology as a Gateway to Future Technology

    Science.gov (United States)

    Asano, Katsuhiko

    Hopes for achieving a new source of energy through nuclear fusion rest on the development of superconducting technology that is needed to make future equipments more energy efficient as well as increase their performance. Superconducting technology has made progress in a wide variety of fields, such as energy, life science, electronics, industrial use and environmental improvement. It enables the actualization of equipment that was unachievable with conventional technology, and will sustain future “IT-Based Quality Life Style”, “Sustainable Environmental” and “Advanced Healthcare” society. Besides coil technology with high magnetic field performance, superconducting electoronics or device technology, such as SQUID and SFQ-circuit, high temperature superconducting material and advanced cryogenics technology might be great significance in the history of nuclear fusion which requires so many wide, high and ultra technology. Superconducting technology seems to be the catalyst for a changing future society with nuclear fusion. As society changes, so will superconducting technology.

  13. The integration of cryogenic cooling systems with superconducting electronic systems

    International Nuclear Information System (INIS)

    Green, Michael A.

    2003-01-01

    The need for cryogenic cooling has been critical issue that has kept superconducting electronic devices from reaching the market place. Even though the performance of the superconducting circuit is superior to silicon electronics, the requirement for cryogenic cooling has put the superconducting devices at a disadvantage. This report will talk about the various methods for refrigerating superconducting devices. Cryocooler types will be compared for vibration, efficiency, and cost. Some solutions to specific problems of integrating cryocoolers to superconducting devices are presented.

  14. Structural/magnetic phase transitions and superconductivity in Ba(Fe1-xTMx)2As2 (TM = Co, Ni, Cu, Co / Cu, Rh and Pd) single crystals

    International Nuclear Information System (INIS)

    Ni, Ni

    2009-01-01

    Since its discovery in 1911, superconductivity has been one of the most actively studied fields in condensed matter physics and has attracted immense experimental and theoretical effort. At this point in time, with more and more superconductors discovered in elements, alloys, intermetallic compounds and oxides, it is becoming clear that superconductivity is actually not so rare in nature. Almost half of the elements in the periodic table and hundreds of compounds have been found to be superconducting. Fig. 1.1 shows the milestones in discovering higher T c superconductors. Among the elemental superconductors, Niobium has the highest superconducting transition temperature, T c , of 9.5 K. This record held for more than ten years, until the discovery of niobium nitride which superconducts below 16 K. It took another thirty years for T c to increase from 16 K in niobium nitride to 23 K in niobium germanium.

  15. Cooperative phenomena in superconducting atom-chips

    Energy Technology Data Exchange (ETDEWEB)

    Fuchs, Sebastian; Kubala, Bjoern; Ankerhold, Joachim [Institut fuer Theoretische Physik, Universitaet Ulm, Albert-Einstein-Allee 11, 89069 Ulm (Germany)

    2013-07-01

    We theoretically investigate the physics of hybrid quantum systems, where a cloud of cold atoms is coupled to superconducting microstructures, so called superconducting atom-chips. Coherent enhancement, due to the large number of atoms in the cloud, opens a path to the study of strong coupling effects, like superradiance/Dicke-physics in a decohering environment. A structured environment can be designed by embedding a Cooper pair box within the cavity. Moreover, in such a system the transfer of quantum information between the atomic cloud and the superconducting solid state system can be studied.

  16. Preliminary study on AC superconducting machines

    International Nuclear Information System (INIS)

    Yamamoto, M.; Ishigohka, T.; Shimohka, T.; Mizukami, N.; Yamaguchi, M.

    1988-01-01

    This paper describes the issues involved in developing AC superconducting machines. In the first phase, as a preliminary experiment, a 4kVa AC superconducting coil which employs 100A class 50/60Hz superconductors is made and tested. And, in the second phase, as an extension of the 4kVa coil, a model superconducting transformer is made and examined. The transformer has a novel quench protection system with an auxiliary coil only in the low voltage side. The behavior of the overcurrent protection system is confirmed

  17. Development of magnetic order in superconducting systems

    International Nuclear Information System (INIS)

    Moncton, D.E.; Shirane, G.; Thomlinson, W.

    1979-08-01

    Two different classes of rare-earth (RE) ternary superconductors (RERh 4 B 4 and REMo 6 S 8 , X=S, Se) have provided the first instances in which chemically ordered sublattices of magnetic ions exist in superconductors. Neutron scattering studies show that simple, conventional antiferromagnetism coexists with superconductivity in a number of systems, while destruction of superconductivity occurs with the onset of ferromagnetism. The magnetic structural details are summarized for the coexistent antiferromagnets, and review measurements on the superconducting → ferromagnetic transition in ErRh 4 B 4

  18. Thermodynamic Green functions in theory of superconductivity

    Directory of Open Access Journals (Sweden)

    N.M.Plakida

    2006-01-01

    Full Text Available A general theory of superconductivity is formulated within the thermodynamic Green function method for various types of pairing mediated by phonons, spin fluctuations, and strong Coulomb correlations in the Hubbard and t-J models. A rigorous Dyson equation for matrix Green functions is derived in terms of a self-energy as a many-particle Green function. By applying the noncrossing approximation for the self-energy, a closed self-consistent system of equations is obtained, similar to the conventional Eliashberg equations. A brief discussion of superconductivity mediated by kinematic interaction with an estimation of a superconducting transition temperature in the Hubbard model is given.

  19. Insulation systems for superconducting transmission cables

    DEFF Research Database (Denmark)

    Tønnesen, Ole

    1996-01-01

    the electrical insulation is placed outside both the superconducting tube and the cryostat. The superconducting tube is cooled by liquid nitrogen which is pumped through the hollow part of the tube.2) The cryogenic dielectric design, where the electrical insulation is placed inside the cryostat and thus is kept......This paper describes shortly the status of superconducting transmission lines and assesses what impact the recently discovered BSCCO superconductors may have on the design of the cables.Two basically different insulation systems are discussed:1) The room temperature dielectric design, where...

  20. Simulation of an HTS Synchronous Superconducting Generator

    DEFF Research Database (Denmark)

    Rodriguez Zermeno, Victor Manuel; Abrahamsen, Asger Bech; Mijatovic, Nenad

    2012-01-01

    In this work we present a simulation of a synchronous generator with superconducting rotor windings. As many other,electrical rotating machines, superconducting generators are exposed to ripple fields that could be produced from a wide variety of sources: short circuit, load change, mechanical...... with an electric load is used to drive the finite element model of a synchronous generator where the current distribution in the rotor windings is assumed uniform. Then, a second finite element model for the superconducting material is linked to calculate the actual current distribution in the windings...

  1. Simulation of an HTS Synchronous Superconducting Generator

    DEFF Research Database (Denmark)

    In this work we present a simulation of a synchronous generator with superconducting rotor windings. As many other electrical rotating machines, superconducting generators are exposed to ripple fields that could be produced from a wide variety of sources: short circuit, load change, etc. Unlike...... element model of a synchronous generator where the current distribution in the rotor windings is assumed uniform. Then, a second finite element model for the superconducting material is linked to calculate the actual current distribution in the windings of the rotor. Finally, heating losses are computed...

  2. Resonant coupling applied to superconducting accelerator structures

    International Nuclear Information System (INIS)

    Potter, James M.; Krawczyk, Frank L.

    2013-01-01

    The concept of resonant coupling and the benefits that accrue from its application is well known in the world of room temperature coupled cavity linacs. Design studies show that it can be applied successfully between sections of conventional elliptical superconducting coupled cavity accelerator structures and internally to structures with spoked cavity resonators. The coupling mechanisms can be designed without creating problems with high field regions or multipactoring. The application of resonant coupling to superconducting accelerators eliminates the need for complex cryogenic mechanical tuners and reduces the time needed to bring a superconducting accelerator into operation.

  3. The cold wars a history of superconductivity

    CERN Document Server

    Matricon, Jean

    1994-01-01

    Among the most peculiar of matter¡¦s behaviors is superconductivity„oelectric current without resistance. Since the 1986 discovery that superconductivity is possible at temperatures well above absolute zero, research into practical applications has flourished. The Cold Wars tells the history of superconductivity, providing perspective on the development of the field and its relationship with the rest of physics. Superconductivity offers an excellent example of the evolution of physics in the twentieth century: the science itself, its foundations, and its social context. The authors also introduce the reader to the fascinating scientific personalities, including 2003 Nobel Prize winners Alexei Alexeievich Abrikosov and Vitali Ginzburg, and political struggles behind this research.

  4. Superconducting detectors for semiconductor quantum photonics

    International Nuclear Information System (INIS)

    Reithmaier, Guenther M.

    2015-01-01

    In this thesis we present the first successful on-chip detection of quantum light, thereby demonstrating the monolithic integration of superconducting single photon detectors with individually addressable semiconductor quantum dots in a prototypical quantum photonic circuit. Therefore, we optimized both the deposition of high quality superconducting NbN thin films on GaAs substrates and the fabrication of superconducting detectors and successfully integrated these novel devices with GaAs/AlGaAs ridge waveguides loaded with self-assembled InGaAs quantum dots.

  5. Superconducting magnets and cryogenics for the steady state superconducting tokamak SST-1

    International Nuclear Information System (INIS)

    Saxena, Y.C.

    2000-01-01

    SST-1 is a steady state superconducting tokamak for studying the physics of the plasma processes in tokamak under steady state conditions and to learn technologies related to the steady state operation of the tokamak. SST-1 will have superconducting magnets made from NbTi based conductors operating at 4.5 K temperature. The design of the superconducting magnets and the cryogenic system of SST-1 tokamak are described. (author)

  6. Durability Evaluation of Superconducting Magnets

    International Nuclear Information System (INIS)

    Inoue, Akihiko; Ogata, Masafumi; Nakauchi, Masahiko; Asahara, Tetsuo; Herai, Toshiki; Nishikawa, Yoichi

    2006-01-01

    It is one of the most essential things to verify the durability of devices and components of JR-Maglev system to realize the system into the future inauguration. Since the load requirements were insufficient in terms of the durability under vibrations under mere running tests carried out on Yamanashi Maglev Test Line hereinafter referred to YMTL, we have developed supplemental method with bench tests. Superconducting magnets hereinafter referred to SCM as used in the experimental running for the last seven years on the YMTL were brought to Kunitachi Technical Research Institute; we conducted tests to evaluate the durability of SCM up to a period of the service life in commercial use. The test results have indicated that no irregularity in each part of SCM proving that SCM are sufficiently durable for the practical application

  7. Superconducting emitters of THz radiation

    Energy Technology Data Exchange (ETDEWEB)

    Welp, Ulrich; Kadowaki, Kazuo; Kleiner, Reinhold

    2013-08-29

    Layered superconductors such as the copper-oxide high-temperature superconductor Bi2Sr2CaCu2O8+δ are emerging as compact sources of coherent continuous-wave electromagnetic radiation in the subterahertz and terahertz frequency ranges. The basis of their operation is the Josephson effect, which intrinsically occurs between the superconducting layers. The Josephson effect naturally converts a direct-current voltage into a high-frequency electric current. Therefore, a unique property of the devices reviewed here is the wide tunability of their frequency by varying the bias voltage. Recently, emission powers of free-space radiation of several hundreds of microwatts and emission linewidths as low as 6 MHz at 600 GHz have been achieved. These devices are promising for new applications in imaging, medical diagnostics, spectroscopy and security.

  8. An experimental superconducting helical undulator

    Energy Technology Data Exchange (ETDEWEB)

    Caspi, S.; Taylor, C. [Lawrence Berkeley Lab., CA (United States)

    1995-12-31

    Improvements in the technology of superconducting magnets for high energy physics and recent advancements in SC materials with the artificial pinning centers (APC){sup 2}, have made a bifilar helical SC device an attractive candidate for a single-pass free electron laser (FEL){sup 3}. Initial studies have suggested that a 6.5 mm inner diameter helical device, with a 27 mm period, can generate a central field of 2-2.5 Tesla. Additional studies have also suggested that with a stored energy of 300 J/m, such a device can be made self-protecting in the event of a quench. However, since the most critical area associated with high current density SC magnets is connected with quenching and training, a short experimental device will have to be built and tested. In this paper we discuss technical issues relevant to the construction of such a device, including a conceptual design, fields, and forces.

  9. Superconducting flux flow digital circuits

    International Nuclear Information System (INIS)

    Martens, J.S.; Zipperian, T.E.; Hietala, V.M.; Ginley, D.S.; Tigges, C.P.; Phillips, J.M.; Siegal, M.P.

    1993-01-01

    The authors have developed a family of digital logic circuits based on superconducting flux flow transistors that show high speed, reasonable signal levels, large fan-out, and large noise margins. The circuits are made from high-temperature superconductors (HTS) and have been shown to operate at over 90 K. NOR gates have been demonstrated with fan-outs of more than 5 and fully loaded switching times less than a fixture-limited 50 ps. Ring-oscillator data suggest inverter delay times of about 40ps when using a 3-μm linewidths. Simple flip-flops have also been demonstrated showing large noise margins, response times of less than 30 ps, and static power dissipation on the order of 30 nW. Among other uses, this logic family is appropriate as an interface between logic families such as single flux quantum and conventional semiconductor logic

  10. Feeding helium to superconducting magnets

    CERN Multimedia

    CERN PhotoLab

    1979-01-01

    The photo shows two of the 3 superconducting magnets (two MBS dipoles (CESAR) of 150 mm bore and 4.5 T, and one quadrupole (CASTOR) of 90 mm bore and 54 T/m) which were installed in the hall EHN1 (Annual Report 1978 p. 134) and ran until 1985. They formed a section of the beam H6 travelling from target T4 (down the bottom of the photo) towards the NA30 setup followed by the NA11 setup. The two big transversal pipelines are the quench lines of the two magnets (on the right, one quadrupole and one dipole, the other dipole lays down the photo and is not visible). The Jura side of the hall is on the right.

  11. Enhancement of the superconducting transition temperature of FeSe by intercalation of a molecular spacer layer.

    Science.gov (United States)

    Burrard-Lucas, Matthew; Free, David G; Sedlmaier, Stefan J; Wright, Jack D; Cassidy, Simon J; Hara, Yoshiaki; Corkett, Alex J; Lancaster, Tom; Baker, Peter J; Blundell, Stephen J; Clarke, Simon J

    2013-01-01

    The discovery of high-temperature superconductivity in a layered iron arsenide has led to an intensive search to optimize the superconducting properties of iron-based superconductors by changing the chemical composition of the spacer layer between adjacent anionic iron arsenide layers. Superconductivity has been found in iron arsenides with cationic spacer layers consisting of metal ions (for example, Li(+), Na(+), K(+), Ba(2+)) or PbO- or perovskite-type oxide layers, and also in Fe(1.01)Se (ref. 8) with neutral layers similar in structure to those found in the iron arsenides and no spacer layer. Here we demonstrate the synthesis of Li(x)(NH(2))(y)(NH(3))(1-y)Fe(2)Se(2) (x~0.6; y~0.2), with lithium ions, lithium amide and ammonia acting as the spacer layer between FeSe layers, which exhibits superconductivity at 43(1) K, higher than in any FeSe-derived compound reported so far. We have determined the crystal structure using neutron powder diffraction and used magnetometry and muon-spin rotation data to determine the superconducting properties. This new synthetic route opens up the possibility of further exploitation of related molecular intercalations in this and other systems to greatly optimize the superconducting properties in this family.

  12. Quench protection in superconducting magnets

    International Nuclear Information System (INIS)

    Shajii, A.; Freidberg, J.P.

    1993-01-01

    The purpose of this obviously non-plasma physics research is to demonstrate that many of the powerful and sophisticated theoretical techniques widely used by the plasma physics community can be applied to engineering problems of direct interest to the magnetic fusion program. Quench protection is such a problem. If a sudden pulse of energy is delivered (usually by accident) to a small section of a superconducting magnet, it may go normal. Under such conditions, the magnet current flows in the surrounding copper matrix, which is essentially in parallel with the superconductor. Although the copper is a good conductor, it still dissipates ohmic power, further adding to the energy input. It is important to detect the quench as early as possible in order to shut off the current, thereby preventing irreversible damage to the conductor. This a non-trivial problem since the cables comprising a coil can be as long as one kilometer. The theory presented here starts with a set of multi-dimensional Navier-Stokes and heat transport equations for the coupled system of helium coolant, superconducting/copper cable, and surrounding jacket. A combination of multiple time scale expansions and asymptotic analysis reduces the problem to a nonlinear fourth order system of 1-D plus time equations. A code has been written whose numerical results are in excellent agreement with more complex engineering codes. There is at least an order of magnitude savings in CPU over the existing codes where a typical run requires one hour Cray CPU. By investigating a number of different cases the authors have been able to introduce further analytic approximations which reduce the problem to quasi-analytic form, a set of three ODE's in time. The results here too are in excellent agreement with the engineering code and requires only several seconds of CPU time. More important, the critical dimensionless parameters have been identified, as well as practical scaling information for the magnet design

  13. Superconducting critical temperature under pressure

    Science.gov (United States)

    González-Pedreros, G. I.; Baquero, R.

    2018-05-01

    The present record on the critical temperature of a superconductor is held by sulfur hydride (approx. 200 K) under very high pressure (approx. 56 GPa.). As a consequence, the dependence of the superconducting critical temperature on pressure became a subject of great interest and a high number of papers on of different aspects of this subject have been published in the scientific literature since. In this paper, we calculate the superconducting critical temperature as a function of pressure, Tc(P), by a simple method. Our method is based on the functional derivative of the critical temperature with the Eliashberg function, δTc(P)/δα2F(ω). We obtain the needed coulomb electron-electron repulsion parameter, μ*(P) at each pressure in a consistent way by fitting it to the corresponding Tc using the linearized Migdal-Eliashberg equation. This method requires as input the knowledge of Tc at the starting pressure only. It applies to superconductors for which the Migdal-Eliashberg equations hold. We study Al and β - Sn two weak-coupling low-Tc superconductors and Nb, the strong coupling element with the highest critical temperature. For Al, our results for Tc(P) show an excellent agreement with the calculations of Profeta et al. which are known to agree well with experiment. For β - Sn and Nb, we found a good agreement with the experimental measurements reported in several works. This method has also been applied successfully to PdH elsewhere. Our method is simple, computationally light and gives very accurate results.

  14. Design of Fluorescent Compounds for Scintillation Detection

    Energy Technology Data Exchange (ETDEWEB)

    Pla-Dalmau, Anna [Northern Illinois U.

    1990-01-01

    Plastic scintillation detectors for high energy physics applications require the development of new fluorescent compounds to meet the demands set by the future generation of particle accelerators such as the Superconducting Supercollider (SSe). Plastic scintillators are commonly based on a polymer matrix doped with two fluorescent compounds: the primary dopant and the wavelength shifter. Their main characteristics are fast response time and high quantum efficiency. The exposure to larger radiation doses and demands for larger light output questions their survivability in the future experiments. A new type of plastic scintillator - intrinsic scintillator - has been suggested. It uses a single dopant as primary and wavelength shifter, and should be less susceptible to radiation damage....

  15. Magnetism and superconductivity of some Tl-Cu oxides

    Science.gov (United States)

    Datta, Timir

    1991-01-01

    Many copper oxide based Thallium compounds are now known. In comparison to the Bi-compounds, the Tl-system shows a richer diversity; i.e., High Temperature Superconductors (HTSC) can be obtained with either one or two Tl-0 layers (m = 1,2); also, the triple-digit phases are easier to synthesize. The value of d, oxygen stoichiometry, is critical to achieving superconductivity. The Tl system is robust to oxygen loss; Tl may be lost or incorporated by diffusion. A diffusion coefficient equal to 10 ms at 900 C was determined. Both ortho-rhombic and tetragonal structures are found, but HTSC behavior is indifferent to the crystal symmetry. This system has the highest T(sub c) confirmed. T(sub c) generally increases with p, the number of CuO layers, but tends to saturate at p = 3. Zero resistance was observed at temperatures as great as 125 K. Most of these HTSC's are hole type, but the Ce-doped specimens may be electronic. The magnetic aspects were studied; because in addition to defining the perfectly diamagnetic ground state as in conventional superconductors, magnetism of the copper oxides show a surprising variety. This is true of both the normal and the superconducting states. Also, due to the large phonon contribution to the specific heat at the high T(sub c) jump, electronic density of states, D(Ef), and coherence length are uncertain, and thus, are estimated from the magnetic results. Results from the Tl-system CuO, LaBaCuO,120 and the Bi-CuO compounds are discussed. The emphasis is on the role of magnetism in the Tl-CuO HTSC, but technological aspects are also pointed out.

  16. Structural feature controlling superconductivity in compressed BaFe2As2

    International Nuclear Information System (INIS)

    Yang, Wenge; Jia, Feng-Jiang; Tang, Ling-Yun; Tao, Qian; Xu, Zhu-An; Chen, Xiao-Jia

    2014-01-01

    Superconductivity can be induced with the application of pressure but it disappears eventually upon heavy compression in the iron-based parent compound BaFe 2 As 2 . Structural evolution with pressure is used to understand this behavior. By performing synchrotron X-ray powder diffraction measurements with diamond anvil cells up to 26.1 GPa, we find an anomalous behavior of the lattice parameter with a S shape along the a axis but a monotonic decrease in the c-axis lattice parameter with increasing pressure. The close relationship between the axial ratio c/a and the superconducting transition temperature T c is established for this parent compound. The c/a ratio is suggested to be a measure of the spin fluctuation strength. The reduction of T c with the further increase of pressure is a result of the pressure-driven weakness of the spin-fluctuation strength in this material

  17. Preparation and characterization of high-Tc superconducting thin films with high critical current densities

    International Nuclear Information System (INIS)

    Vase, P.

    1991-08-01

    The project was carried out in relation to possible cable and electronics applications of high-T c materials. Laser ablation was used as the deposition technique because of its stoichiometry conservation. Films were made in the YBa 2 Cu 3 O 7 compound due to its relatively simple stoichiometry compared to other High-T c compounds. Much attention was paid to the critical current density. A very high critical current density was reached. By using texture analysis by X-ray diffraction, it was found that films with high critical current densities were epitaxial, while films with low critical current densities contained several crystalline orientations. Four techniques for patterning the films were used - photo lithography and wet etch, laser ablation lithography, laser writing and electron beam lithography and ion milling. Sub-micron patterning has been demonstrated without degradation of the superconducting properties. The achieved patterning resolution is sufficient for preparation of many superconducting components. (AB)

  18. Transparency of atom-sized superconducting junctions

    International Nuclear Information System (INIS)

    Van-der-Post, N.; Peters, E.T.; Van Ruitenbeek, J.M.; Yanson, I.K.

    1995-01-01

    We discuss the transparency of atom-size superconducting tunnel junctions by comparing experimental values of the normal resistance and Subgap Structure with the theoretical predictions for these phenomena by Landauer's formula and Multiple Andreev Reflection, respectively

  19. Magnetic fluctuations and heavy electron superconductivity

    International Nuclear Information System (INIS)

    Norman, M.R.

    1988-01-01

    A magnetic fluctuation self-energy based on neutron scattering data is used to calculate mass renormalizations, and superconducting critical temperatures and order parameters, for various heavy electron metals

  20. Operational experience with superconducting synchrotron magnets

    International Nuclear Information System (INIS)

    Martin, P.S.

    1987-03-01

    The operational experience with the Fermilab Tevatron is presented, with emphasis on reliability and failure modes. Comprisons are made between the operating efficiencies for the superconducting machine and for he conventional Main Ring

  1. Inhomogeneous LOFF phase revisited for surface superconductivity

    Science.gov (United States)

    Barzykin, Victor; Gor'kov, Lev P.

    2003-03-01

    We consider 2D surface superconductivity in high magnetic fields parallel to the surface. We demonstrate that the spin-orbit interaction at the surface changes the properties of the inhomogeneous superconducting Larkin-Ovchinnikov-Fulde-Ferrell state that develops above fields given by the paramagnetic criterion. Strong spin-orbit interaction significantly broadens the range of existence of the LOFF phase, which takes the form of periodic superconducting stripes running along the field direction on the surface, leading to the anisotropy of its properties. We also discuss this problem for the d-wave pairing to indicate the possibility of a re-orientation transition as the magnetic field direction is rotated in the plane parallel to the surface. Our results provide a tool for studying surface superconductivity This work was supported in part by NHMFL through the NSF Cooperative agreement No. DMR-9521035 and the State of Florida, in part (VB) by the University of Tennessee.

  2. Superconducting magnet coils protection schemes and apparatus

    International Nuclear Information System (INIS)

    Kuchinski, V.; Bulgakov, S.; Larionov, B.; Mikhailov, N.; Silin, V.

    1995-01-01

    The circuitry of the superconducting coils protection system of the large fusion installations is analyzed. The requirements to the switches and several options of the circuit breakers and making switches with the data of their experimental study are discussed. (orig.)

  3. Electrical insulation for large multiaxis superconducting magnets

    International Nuclear Information System (INIS)

    Harvey, A.R.; Rinde, J.A.

    1975-01-01

    The selection of interturn and interlayer insulation for superconducting magnets is discussed. The magnet problems of the Baseball II device are described. Manufacture of the insulation and radiation damage are mentioned. A planned experimental program is outlined

  4. Superconducting magnet radiation effects in fusion reactors

    International Nuclear Information System (INIS)

    Sawan, M.E.; Walstrom, P.L.

    1986-01-01

    Radiation effects in superconducting magnets of fusion reactors are analyzed and experimental data reviewed. The interaction between the different radiation effects and impact on reactor design is discussed. The need for experimental data with higher irradiation levels is assessed

  5. Superconducting RF for energy-recovery linacs

    International Nuclear Information System (INIS)

    Liepe, M.; Knobloch, J.

    2006-01-01

    Since superconducting RF for particle accelerators made its first appearance in the 1970s, it has found highly successful application in a variety of machines. Recent progress in this technology has made so-called Energy-Recovery Linacs (ERLs)-originally proposed in 1965-feasible, and interest in this type of machine has increased enormously. A superconducting linac is the driving heart of ERLs, and emittance preservation and cost efficiency is of utmost importance. The resulting challenges for the superconducting cavity technology and RF field control are manifold. In March 2005 the first international workshop on ERLs was held at Newport News, VA, to explore the potential of ERLs and to discuss machine-physics and technology challenges and their solutions. This paper reviews the state-of-the-art in superconducting RF and RF control for ERLs, and summarizes the discussions of the SRF working group on this technology during the ERL2005 workshop

  6. Radiation considerations for superconducting fusion magnets

    International Nuclear Information System (INIS)

    Abdou, M.A.

    1977-01-01

    Radiation environment for the magnets is characterized for various conditions expected for tokamak power reactor operation. The radiation levels are translated into radiation effects using available experimental data. The impact of the tradeoffs in radiation shielding and the change in the properties of the superconducting magnets on reactor performance and economics is examined. It is shown that (1) superconducting magnets in fusion reactors will operate at much higher radiation level than was previously anticipated; (2) additional data on radiation damage is required to better accuracy than is presently available in order to accurately quantify the change in properties in the superconducting magnet components; and (3) there is a substantial penalty for increasing (or overestimating) the shielding requirements. A perspective of future tokamak power reactors is presented and questions relating to desirable magnetic field strength and selection of materials for superconducting magnets are briefly examined

  7. Degreasing and cleaning superconducting RF Niobium cavities

    Energy Technology Data Exchange (ETDEWEB)

    Rauchmiller, Michael; Kellett, Ron; /Fermilab

    2011-09-01

    The purpose and scope of this report is to detail the steps necessary for degreasing and cleaning of superconducting RF Niobium cavities in the A0 clean room. It lists the required equipment and the cleaning procedure.

  8. Superconducting inductive displacement detection of a microcantilever

    Energy Technology Data Exchange (ETDEWEB)

    Vinante, A., E-mail: anvinante@fbk.eu [Istituto di Fotonica e Nanotecnologie, CNR - Fondazione Bruno Kessler, I-38123 Povo, Trento (Italy)

    2014-07-21

    We demonstrate a superconducting inductive technique to measure the displacement of a micromechanical resonator. In our scheme, a type I superconducting microsphere is attached to the free end of a microcantilever and approached to the loop of a dc Superconducting Quantum Interference Device (SQUID) microsusceptometer. A local magnetic field as low as 100 μT, generated by a field coil concentric to the SQUID, enables detection of the cantilever thermomechanical noise at 4.2 K. The magnetomechanical coupling and the magnetic spring are in good agreement with image method calculations assuming pure Meissner effect. These measurements are relevant to recent proposals of quantum magnetomechanics experiments based on levitating superconducting microparticles.

  9. Superconducting technology program Sandia 1996 annual report

    International Nuclear Information System (INIS)

    Roth, E.P.

    1997-02-01

    Sandia's Superconductivity Technology Program is a thallium-based high-temperature superconductor (HTS) research and development program consisting of efforts in powder synthesis and process development, open-system thick film conductor development, wire and tape fabrication, and HTS motor design. The objective of this work is to develop high-temperature superconducting conductors (wire and tape) capable of meeting requirements for high-power electrical devices of interest to industry. The research efforts currently underway are: (1) Process development and characterization of thallium-based high-temperature superconducting closed system wire and tape, (2) Investigation of the synthesis and processing of thallium-based thick films using two-zone processing, and (3) Cryogenic design of a 30K superconducting motor. This report outlines the research that has been performed during FY96 in each of these areas

  10. Superconductivity in alkali-doped C60

    International Nuclear Information System (INIS)

    Ramirez, Arthur P.

    2015-01-01

    Highlight: • Superconductivity in alkali-doped C 60 (A 3 C 60 ) is well described by an s-wave state produced by phonon mediated pairing. • Moderate coupling of electrons to high-frequency shape-changing intra-molecular vibrational modes produces transition temperatures up to 33 K in single-phase material. • The good understanding of pairing in A 3 C 60 offers a paradigm for the development of new superconducting materials. - Abstract: Superconductivity in alkali-doped C 60 (A 3 C 60 , A = an alkali atom) is well described by an s-wave state produced by phonon mediated pairing. Moderate coupling of electrons to high-frequency shape-changing intra-molecular vibrational modes produces transition temperatures (T c ) up to 33 K in single-phase material. The good understanding of pairing in A 3 C 60 offers a paradigm for the development of new superconducting materials

  11. Superconducting generator technology--an overview

    International Nuclear Information System (INIS)

    Edmonda, J.S.

    1979-01-01

    Application of superconducting technology to field windings of large ac generators provides virtually unlimited field capability without incurring resistive losses in the winding. Several small-scale superconducting generators have been built and tested demonstrating the feasibility of such concepts. For machines of much larger capacity, conceptual designs for 300 Mva and 1200 Mva have been completed. The development of a 300 Mva generator is projected. Designed, engineered and fabricated as a turbo generator, the superconducting machine is to be installed in a power plant, tested and operated in concert with a prime mover, the steam generator and the auxiliary support systems of the power plant. This will provide answers to the viability of operating a superconducting machine and its cryogenic handling systems in a full time, demanding environment. 21 refs

  12. Superconducting Aero Propulsion Motor, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Superconducting electric propulsion systems will yield improvements in total ownership costs due to the simplicity of electric drive when compared with gas turbine...

  13. Superconducting magnets in high energy physics

    International Nuclear Information System (INIS)

    Prodell, A.G.

    1978-01-01

    The applications of superconducting magnets in high energy physics in the last ten years have made feasible developments which are vital to high energy research. These developments include high magnetic field, large volume detectors, such as bubble chambers, required for effective resolution of high energy particle trajectories, particle beam transport magnets, and superconducting focusing and bending magnets for the very high energy accelerators and storage rings needed to pursue the study of interactions between elementary particles. The acceptance of superconductivity as a proven technology in high energy physics was reinforced by the recognition that the existing large accelerators using copper-iron magnets had reached practical limits in terms of magnetic field intensity, cost, space, and energy usage, and that large-volume, high-field, copper-iron magnets were not economically feasible. Some of the superconducting magnets and associated systems being used in and being developed for high energy physics are described

  14. Superconductivity in Washington, D.C

    International Nuclear Information System (INIS)

    Ritter, D.

    1988-01-01

    The author provides insights into the federal government's activity in superconductors. He says the President's most important legislative proposal is a change in anti-trust laws to allow businesses to cooperate on joint production ventures. The President has also directed the Department of Energy, the Department of Commerce, the National Aeronautics and Space Administration, the National Science Foundation, and the Department of Defense to establish Superconductivity Research Centers to conduct research and disseminate information. The author says he thinks it is worthwhile to pursue the President's proposal for cooperation with Japan in superconductivity research and development. The author explains why he supports this and other key legislation related to superconductivity. He says if the United States does not do all that it can, as fast as it can, both domestically and internationally, the U.S. could lose the cutting edge of technological and commercial leadership in the latter 20th century and the 21st century. This is what superconductivity represents

  15. Structural aspects of superconducting fusion magnets

    International Nuclear Information System (INIS)

    Reich, M.; Lehner, J.; Powell, J.

    1977-01-01

    Some methods for studying various static, dynamic, elastic-plastic, and fracture mechanics problems of superconducting magnets are described. Sample solutions are given for the UWMAK-I magnet. Finite element calculations were used

  16. Superfluidity and Superconductivity in Neutron Stars

    Indian Academy of Sciences (India)

    Neutron stars, the compact stellar remnants of core-collapse supernova explosions, are unique cosmic laboratories for exploring novel phases of matter under extreme conditions. In particular, the occurrence of superfluidity and superconductivity in neutron stars will be briefly reviewed.

  17. The study of superconducting order parameter dynamics

    International Nuclear Information System (INIS)

    Goldman, A.M.

    1988-01-01

    Flux quantization experiments have demonstrated the importance of long range phase coherence in the description of the superconducting state, an idea originally proposed as an integral part of the phenomenological theory of the Meissner-Ochsenfeld effect. The most striking experimental demonstration of the phase coherence of the superconducting state is that the maximum dc Josephson current in a thin-film tunneling junction exhibits a Fraunhofer-like dependence on magnetic field

  18. 13th European Conference on Applied Superconductivity

    CERN Document Server

    2017-01-01

    EUCAS is a worldwide forum for scientists and engineers, and provides an ideal platform to share knowledge and the most recent advances in all areas of applied superconductivity: from large-scale applications to miniature electronics devices, with a traditional focus on advanced materials and conductors. The broad scope is at the same time a challenge and an opportunity to foster novel, inter-disciplinary approaches and promote cross-fertilization among the various fields of applied superconductivity.

  19. Superconducting poloidal coils for STARFIRE commercial reactor

    International Nuclear Information System (INIS)

    Wang, S.T.; Evans, K. Jr.; Turner, L.R.; Huang, Y.C.; Prater, R.; Alcorn, J.

    1979-01-01

    STARFIRE is considered to be the tenth commercial tokamak power plant. A preliminary design study on its superconducting poloidal coil system is presented. Key features of the design studies are: the elimination of the ohmic heating coil; the trade-off studies of the equilibrium field coil locations; and the development of a conceptual design for the superconducting equilibrium field coils. Described are the 100 kA cryostable conductor design, the coil structure, and evaluation of the coil forces

  20. Inelastic neutron scattering from superconducting rings

    International Nuclear Information System (INIS)

    Agafonov, A.I.

    2010-01-01

    For the first time the differential cross section for the inelastic magnetic neutron scattering by superconducting rings is derived taking account of the interaction of the neutron magnetic moment with the magnetic field generated by the superconducting current. Calculations of the scattering cross section are carried out for cold neutrons and thin film rings from type-II superconductors with the magnetic fields not exceeding the first critical field.