Experimental and Computational Studies of the Superconducting Phase Transition of Quasi 1D Superconductors

Science.gov (United States)

Wong, Chi Ho

In this PhD project, the feasibility of establishing a state with vanishing resistance in quasi-1D superconductors are studied. In the first stage, extrinsic quasi-1D superconductors based on composite materials made by metallic nanowire arrays embedded in mesoporous silica substrates, such as Pb-SBA-15 and NbN-SBA-15 (fabricated by a Chemical Vapor Deposition technique) are investigated. Two impressive outcomes in Pb-SBA-15 are found, including an enormous enhancement of the upper critical field from 0.08T to 14T and an increase of the superconducting transition temperature onset s from 7.2 to 11K. The second stage is to apply Monte Carlo simulations to model the quasi-1D superconductor, considering its penetration depth, coherence length, defects, electron mean free path, tunneling barrier and insulating width between the nanowires. The Monte Carlo results provide a clear picture to approach to stage 3, which represents a study of the intrinsic quasi-1D superconductor Sc3CoC4, which contains parallel arrays of 1D superconducting CoC4 ribbons with weak transverse Josephson or Proximity interaction, embedded in a Sc matrix. According to our previous work, a BKT transition in the lateral plane is believed to be the physics behind the vanishing resistance of quasi-1D superconductors, because it activates a dimensional crossover from a 1D fluctuating superconductivity at high temperature to a 3D bulk phase coherent state in the entire material at low temperatures. Moreover, we decided to study thin 1D Sn nanowires without substrate, which display very similar superconducting properties to Pb-SBA-15 with a strong critical field and Tc enhancement. Finally, a preliminary research on a novel quasi-2D superconductor formed by parallel 2D mercury sheets that are separated by organic molecules is presented. The latter material may represent a model system to study the effect of a layered structure, which is believed to be an effective ingredient to design high temperature

Role of disorder in the multi-critical region of d-wave superconductivity and antiferromagnetism

International Nuclear Information System (INIS)

Yanase, Youichi; Ogata, Masao

2007-01-01

We investigate the disorder-induced microscopic inhomogeneity in the multi-critical region of d-wave superconductivity and antiferromagnetism on the basis of the microscopic t-t ' -U-V model. We find that a small amount of point disorder induces the nano-scale inhomogeneity of spin and superconducting fluctuations when the coherence length of superconductivity is remarkably short as in the under-doped cuprates. Then, the two fluctuations spatially segregate to avoid their competition. We show the remarkable electron-hole asymmetry in high-T c cuprates where the quite different spatial structure is expected in the electron-doped materials

New world of Gossamer superconductivity

Energy Technology Data Exchange (ETDEWEB)

Maki, Kazumi; Haas, Stephan; Parker, David [Department of Physics and Astronomy, University of Southern California, Los Angeles, CA 90089-0484 (United States); Won, Hyekyung [Max-Planck-Institut fuer Physik komplexer Systeme, Noethnitzer Str. 38, 01187, Dresden (Germany); Department of Physics, Hallym University, Chuncheon 200-702 (Korea); Dora, Balazs; Virosztek, Attila [Department of Physics, Budapest University of Technology and Economics, 1521 Budapest (Hungary)

2006-09-15

Since the discovery of the high-T {sub c} cuprate superconductor La{sub 2-x}BaCuO{sub 4} in 1986 by Bednorz and Mueller, controversy regarding the nature or origin of this remarkable superconductivity has continued. However, d-wave superconductivity in the hole-doped cuprates, arising due to the anti-paramagnon exchange, was established around 1994. More recently we have shown that the mean field theory, like the BCS theory of superconductivity and Landau's Fermi liquid theory are adequate to describe the cuprates. The keys for this development are the facts that a) the pseudogap phase is d-wave density wave (dDW) and that the high-T{sub c} cuprate superconductivity is gossamer (i.e. it exists in the presence of dDW). (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

The Study about Application of Transportation System of the Superconductive Electromagnetism Propulsion in the Harbor

OpenAIRE

涌井, 和也; 荻原, 宏康

1999-01-01

Electromagnetic propulsion is promising technique for a linear motor car, a ship and a space ship, in future. W. A Rice developed an electromagnetic pump for the liquid metal transfer. There are two electromagnetic propulsions : a superconductive electricity propulsion and a superconductive electromagnetic propulsion. A superconductive electricity propulsion ship uses a screw driven by a superconducting motor. This technique has merits of excellent navigation-ability, and the free degree of t...

A 3D printed superconducting aluminium microwave cavity

Energy Technology Data Exchange (ETDEWEB)

Creedon, Daniel L. [School of Physics, University of Melbourne, Parkville, Victoria 3010 (Australia); Goryachev, Maxim; Kostylev, Nikita; Tobar, Michael E., E-mail: michael.tobar@uwa.edu.au [ARC Centre of Excellence for Engineered Quantum Systems, University of Western Australia, 35 Stirling Highway, Crawley, WA 6009 (Australia); Sercombe, Timothy B. [School of Mechanical and Chemical Engineering, University of Western Australia, 35 Stirling Highway, Crawley 6009 (Australia)

2016-07-18

3D printing of plastics, ceramics, and metals has existed for several decades and has revolutionized many areas of manufacturing and science. Printing of metals, in particular, has found a number of applications in fields as diverse as customized medical implants, jet engine bearings, and rapid prototyping in the automotive industry. Although many techniques are used for 3D printing metals, they commonly rely on computer controlled melting or sintering of a metal alloy powder using a laser or electron beam. The mechanical properties of parts produced in such a way have been well studied, but little attention has been paid to their electrical properties. Here we show that a microwave cavity (resonant frequencies 9.9 and 11.2 GHz) 3D printed using an Al-12Si alloy exhibits superconductivity when cooled below the critical temperature of aluminium (1.2 K), with a performance comparable with the common 6061 alloy of aluminium. Superconducting cavities find application in numerous areas of physics, from particle accelerators to cavity quantum electrodynamics experiments. The result is achieved even with a very large concentration of non-superconducting silicon in the alloy of 12.18%, compared with Al-6061, which has between 0.4% and 0.8%. Our results may pave the way for the possibility of 3D printing superconducting cavity configurations that are otherwise impossible to machine.

A 3D printed superconducting aluminium microwave cavity

International Nuclear Information System (INIS)

Creedon, Daniel L.; Goryachev, Maxim; Kostylev, Nikita; Tobar, Michael E.; Sercombe, Timothy B.

2016-01-01

3D printing of plastics, ceramics, and metals has existed for several decades and has revolutionized many areas of manufacturing and science. Printing of metals, in particular, has found a number of applications in fields as diverse as customized medical implants, jet engine bearings, and rapid prototyping in the automotive industry. Although many techniques are used for 3D printing metals, they commonly rely on computer controlled melting or sintering of a metal alloy powder using a laser or electron beam. The mechanical properties of parts produced in such a way have been well studied, but little attention has been paid to their electrical properties. Here we show that a microwave cavity (resonant frequencies 9.9 and 11.2 GHz) 3D printed using an Al-12Si alloy exhibits superconductivity when cooled below the critical temperature of aluminium (1.2 K), with a performance comparable with the common 6061 alloy of aluminium. Superconducting cavities find application in numerous areas of physics, from particle accelerators to cavity quantum electrodynamics experiments. The result is achieved even with a very large concentration of non-superconducting silicon in the alloy of 12.18%, compared with Al-6061, which has between 0.4% and 0.8%. Our results may pave the way for the possibility of 3D printing superconducting cavity configurations that are otherwise impossible to machine.

A 3D printed superconducting aluminium microwave cavity

Science.gov (United States)

Creedon, Daniel L.; Goryachev, Maxim; Kostylev, Nikita; Sercombe, Timothy B.; Tobar, Michael E.

2016-07-01

3D printing of plastics, ceramics, and metals has existed for several decades and has revolutionized many areas of manufacturing and science. Printing of metals, in particular, has found a number of applications in fields as diverse as customized medical implants, jet engine bearings, and rapid prototyping in the automotive industry. Although many techniques are used for 3D printing metals, they commonly rely on computer controlled melting or sintering of a metal alloy powder using a laser or electron beam. The mechanical properties of parts produced in such a way have been well studied, but little attention has been paid to their electrical properties. Here we show that a microwave cavity (resonant frequencies 9.9 and 11.2 GHz) 3D printed using an Al-12Si alloy exhibits superconductivity when cooled below the critical temperature of aluminium (1.2 K), with a performance comparable with the common 6061 alloy of aluminium. Superconducting cavities find application in numerous areas of physics, from particle accelerators to cavity quantum electrodynamics experiments. The result is achieved even with a very large concentration of non-superconducting silicon in the alloy of 12.18%, compared with Al-6061, which has between 0.4% and 0.8%. Our results may pave the way for the possibility of 3D printing superconducting cavity configurations that are otherwise impossible to machine.

Specific heat of holmium and YNi2B2C. Criticalbehaviour and superconducting properties

International Nuclear Information System (INIS)

Bekkali, Abdelhakim

2010-01-01

Object of the thesis is the study of the specific heat of holmium and YNi 2 B 2 C in the temperature ranges from 50 to 200 KI respectively from 380 mK to 20 K in magnetic fields up to 9 T. In the present thesis the criticalbehaviour of YNi 2 B 2 C and properties of the superconducting state of tne non-magnetic rare-earth nickel borocarbide YNi 2 B 2 C are studied by means of a self-developed measurement apparatur of the specific heat using the quasi-adiabatic heating-pulse method as well as of holmium by means of the relaxation method. In this thesis reliable statements about the critical exponents on monocrystalline holmium could be made. The study on holmium proves that the critical behaviour of the specific heats cannot be described in the framework of the predictions of the chiral universality classes. By means of measurements of the specific heat in this thesis could be confirmed that YNi 2 B 2 C is a multiband superconductor. The positive curvature of the boundary line below T c in the phase diagram yields a first hint to the many-band character of YNI 2 B 2 C. In the zero-field the electronic specific heat in the superconducting state c es (T) can be not explained in the framework of the pure BCS theory. At low temperatures a residual contribution by normally conducting electrons could be detected, which hints to a not completely opened energy gap. A possible explanation would be that a band (or several bands) with low charge-carrier concentration not contribute to the superconductivity. This result agrees with de Haas-van Alphen measurements on isostructural superconducting LuNi 2 B 2 C monocrystals, which suggest the many-band character of the superconductivity as well as a vanishing energy gap in one band. The fluctuation behaviour of the specific heat of YNi 2 B 2 C in the neighbourhood of the superconducting-normally conducting transition agrees well with that of the 3D-XY model. [de

1D-transport properties of single superconducting lead nanowires

DEFF Research Database (Denmark)

Michotte, S.; Mátéfi-Tempfli, Stefan; Piraux, L.

2003-01-01

of the nanowire is small enough to ensure a 1D superconducting regime in a wide temperature range below T. The non-zero resistance in the superconducting state and its variation caused by fluctuations of the superconducting order parameter were measured versus temperature, magnetic field, and applied DC current......We report on the transport properties of single superconducting lead nanowires grown by an electrodeposition technique, embedded in a nanoporous track-etched polymer membrane. The nanowires are granular, have uniform diameter of ̃40 nm and a very large aspect ratio (̃500). The diameter...

Magnetic field systems employing a superconducting D.C. field coil

International Nuclear Information System (INIS)

Bartram, T.C.; Hazell, P.A.

1977-01-01

Method and equipment for transferring energy to or from a direct-current superconducting field coil to change the magnetic field generated by the coil in which a second direct-current superconducting coil is used as a storage coil, and energy transfer between the field coil and the storage coil is effected automatically in dependence upon a control program. Preferably, the control program acts upon a variable transformer which is coupled by respective rectifier/inverters to the field and storage coils and also serves for intital supply of energy to the coils

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

High-Tc superconductivity in the d-p electron system

International Nuclear Information System (INIS)

Ivanov, V.A.; Zaitsev, R.A.

1991-01-01

The relaxation time with spin flip τ s and the parameters ξ, δ, χ of superconducting phase have been calculated on the basis of the kinematical mechanism of superconductivity in strongly correlated oxide models. An inter-relation between the superconducting gap Δ o and the specific heat jump Δ c allowing the experimental verification was obtained and the Ginsburg-Landau equation derived. (author). 8 refs., 2 figs

Antiferromagnetism and d-wave superconductivity in the Hubbard model

Energy Technology Data Exchange (ETDEWEB)

Krahl, H.C.

2007-07-25

The two-dimensional Hubbard model is a promising effective model for the electronic degrees of freedom in the copper-oxide planes of high temperature superconductors. We present a functional renormalization group approach to this model with focus on antiferromagnetism and d-wave superconductivity. In order to make the relevant degrees of freedom more explicitly accessible on all length scales, we introduce composite bosonic fields mediating the interaction between the fermions. Spontaneous symmetry breaking is reflected in a non-vanishing expectation value of a bosonic field. The emergence of a coupling in the d-wave pairing channel triggered by spin wave fluctuations is demonstrated. Furthermore, the highest temperature at which the interaction strength for the electrons diverges in the renormalization flow is calculated for both antiferromagnetism and d-wave superconductivity over a wide range of doping. This ''pseudo-critical'' temperature signals the onset of local ordering. Moreover, the temperature dependence of d-wave superconducting order is studied within a simplified model characterized by a single coupling in the d-wave pairing channel. The phase transition within this model is found to be of the Kosterlitz-Thouless type. (orig.)

3D Integration for Superconducting Qubits

Science.gov (United States)

Rosenberg, Danna; Kim, David; Yost, Donna-Ruth; Mallek, Justin; Yoder, Jonilyn; Das, Rabindra; Racz, Livia; Hover, David; Weber, Steven; Kerman, Andrew; Oliver, William

Superconducting qubits are a prime candidate for constructing a large-scale quantum processor due to their lithographic scalability, speed, and relatively long coherence times. Moving beyond the few qubit level, however, requires the use of a three-dimensional approach for routing control and readout lines. 3D integration techniques can be used to construct a structure where the sensitive qubits are shielded from a potentially-lossy readout and interconnect chip by an intermediate chip with through-substrate vias, with indium bump bonds providing structural support and electrical conductivity. We will discuss our work developing 3D-integrated coupled qubits, focusing on the characterization of 3D integration components and the effects on qubit performance and design. This research was funded by the Office of the Director of National Intelligence (ODNI), Intelligence Advanced Research Projects Activity (IARPA) via MIT Lincoln Laboratory 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.

High-T/sub c/ superconductor and its use in superconducting magnets

International Nuclear Information System (INIS)

Green, M.A.

1988-02-01

Many of the proposed uses for the high-T/sub c/ superconductor involve the creation of a magnetic field using superconducting coils. This report will assess what is known about the high-T/sub c/ superconductors and take a realistic look at their potential use in various kinds of superconducting magnets. Based on what is known about the high-T/sub c/ superconductors, one can make a ''wish list'' of things that will make such materials useful for magnets. Then, the following question is asked. If one had a high-T/sub c/ superconductor with the same properties as modern niobium-titanium superconductor, how would the superconductor work in a magnet environment? Finally, this report will show the potential impact of the ideal high-T/sub c/ superconductor on: 1) accelerator dipole and quadrupole magnets, 2) superconducting magnets for use in space, and 3) superconducting solenoids for magnetic resonance imaging. 78 refs., 11 tabs

Incipient localization and tight-binding superconductivity: Tsub(c) calculation

International Nuclear Information System (INIS)

Kolley, E.; Kolley, W.

1984-01-01

Localization effects on the superconducting transition temperature Tsub(c) are examined in strongly disordered three-dimensional systems. A tight-binding formulation of strong-coupling superconductivity is combined, after configuration averaging, with the self-consistent treatment of Anderson localization developed by Vollhardt and Woelfle. The Coulomb interaction becomes retarded via the joint local local density of states, giving rise to an enhancement of the pseudopotential. Numerical Tsub(c) results as a function of disorder are compared with another theoretical work and experimental values for some high-Tsub(c) materials. (orig.)

Towards room-temperature superconductivity in low-dimensional C60 nanoarrays: An ab initio study

Science.gov (United States)

Erbahar, Dogan; Liu, Dan; Berber, Savas; Tománek, David

2018-04-01

We propose to raise the critical temperature Tc for superconductivity in doped C60 molecular crystals by increasing the electronic density of states at the Fermi level N (EF) and thus the electron-phonon coupling constant in low-dimensional C60 nanoarrays. We consider both electron and hole dopings and present numerical results for N (EF) , which increases with the decreasing bandwidth of the partly filled hu- and t1 u-derived frontier bands with the decreasing coordination number of C60. Whereas a significant increase in N (EF) occurs in two-dimensional (2D) arrays of doped C60 intercalated in-between graphene layers, we propose that the highest-Tc values approaching room temperature may occur in bundles of nanotubes filled by one-dimensional (1D) arrays of externally doped C60 or La @C60 or in diluted three-dimensional (3D) crystals where quasi-1D arrangements of C60 form percolation paths.

Design and manufacture of a large superconducting homopolar motor (and status of superconducting a.c. generator)

International Nuclear Information System (INIS)

Appleton, A.D.

1983-01-01

This paper describes the design and manufacture of a large superconducting motor which, in the present time of financial restraints, is continuing at least to the point of having a completed cryostat with its superconducting winding operating with a dedicated helium refrigeration plant. Comments are also made on the superconducting a.c. generator project, although a final decision on the rating of a prototype and the approval of the funding has not yet been made, the selected rating is expected to be between 200 MW and 600 MW

Modal bifurcation in a high-T{sub c} superconducting levitation system

Energy Technology Data Exchange (ETDEWEB)

Taguchi, D; Fujiwara, S; Sugiura, T, E-mail: sugiura@mech.keio.ac.jp [Department of Mechanical Engineering, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, kohoku-ku, Yokohama 223-8522 (Japan)

2011-05-15

This paper deals with modal bifurcation of a multi-degree-of-freedom high-T{sub c} superconducting levitation system. As modeling of large-scale high-T{sub c} superconducting levitation applications, where plural superconducting bulks are often used, it can be helpful to consider a system constituting of multiple oscillators magnetically coupled with each other. This paper investigates nonlinear dynamics of two permanent magnets levitated above high-T{sub c} superconducting bulks and placed between two fixed permanent magnets without contact. First, the nonlinear equations of motion of the levitated magnets were derived. Then the method of averaging was applied to them. It can be found from the obtained solutions that this nonlinear two degree-of-freedom system can have two asymmetric modes, in addition to a symmetric mode and an antisymmetric mode both of which also exist in the linearized system. One of the backbone curves in the frequency response shows a modal bifurcation where the two stable asymmetric modes mentioned above appear with destabilization of the antisymmetric mode, thus leading to modal localization. These analytical predictions have been confirmed in our numerical analysis and experiments of free vibration and forced vibration. These results, never predicted by linear analysis, can be important for application of high-T{sub c} superconducting levitation systems.

TRILEX and G W +EDMFT approach to d -wave superconductivity in the Hubbard model

Science.gov (United States)

Vučičević, J.; Ayral, T.; Parcollet, O.

2017-09-01

We generalize the recently introduced TRILEX approach (TRiply irreducible local EXpansion) to superconducting phases. The method treats simultaneously Mott and spin-fluctuation physics using an Eliashberg theory supplemented by local vertex corrections determined by a self-consistent quantum impurity model. We show that, in the two-dimensional Hubbard model, at strong coupling, TRILEX yields a d -wave superconducting dome as a function of doping. Contrary to the standard cluster dynamical mean field theory (DMFT) approaches, TRILEX can capture d -wave pairing using only a single-site effective impurity model. We also systematically explore the dependence of the superconducting temperature on the bare dispersion at weak coupling, which shows a clear link between strong antiferromagnetic (AF) correlations and the onset of superconductivity. We identify a combination of hopping amplitudes particularly favorable to superconductivity at intermediate doping. Finally, we study within G W +EDMFT the low-temperature d -wave superconducting phase at strong coupling in a region of parameter space with reduced AF fluctuations.

Overview of superconductivity in Japan Strategy road map and R&D status

Science.gov (United States)

Tsukamoto, O.

2008-09-01

Superconducting technology benefits society in broad fields; environment/energy, life science, manufacturing industry and information and communication. Superconducting equipments and devices used in various fields are divided into two categories, electric and electronic applications. Technologies in those applications are progressing remarkably owing to firm and consistent supports by various national projects. The final target of the NEDO R&D project of fundamental technology for superconductivity applications to develop 500 m long coated conductors (CCs) of the critical current 300 A/cm (at 77 K, 0 T) will be fulfilled by the end of JFY 2007 and manufacturing process to produce extremely low-cost CCs is to be developed to make the applications realistic. Preliminary works to develop power apparatuses using CCs have started in the frame of the R&D project for the fundamental technology and have produced significant results. Performance of BSCCO/Ag-sheathed wires has been improved greatly and various applications using those wires are being developed. R&D projects for SMES, power cable, flywheel energy storage and rotating machines are going to introduce those equipments to the real world. Technologies of SQUID and SFQ, basic devices of the electronic applications, are progressing dramatically also owing to various national projects. In this back ground the technology strategy map in the field of superconducting technology was formulated to prioritize investments in R&D by clearly defining the objectives and inspire autonomous R&D actives in various fields of industries. R&D activities in the superconducting technologies are to be scheduled following this strategy map.

Superconductivity in the W-Tc and W2C-Tc systems

International Nuclear Information System (INIS)

Giorgi, A.L.

1985-01-01

A series of compositions in the W-Tc, W 2 C-Re and W 2 C-Tc systems were prepared and examined for superconductivity. The crystal structure, lattice parameters and superconducting transition temperatures of the W 2 C-Tc are reported for the first time. Similar measurements were made on the W-Tc and W 2 C-Re systems and the results compared with previous published results for these systems. 7 refs., 2 figs., 2 tabs

Tuning of superconductivity by Ni substitution into noncentrosymmetric ThC o1 -xN ixC2

Science.gov (United States)

Grant, T. W.; Cigarroa, O. V.; Rosa, P. F. S.; Machado, A. J. S.; Fisk, Z.

2017-07-01

The recently discovered noncentrosymmetric superconductor ThCoC2 was observed to show unusual superconducting behavior with a critical temperature of Tc=2.65 K . Here we investigate the effect of nickel substitution on the superconducting state in ThC o1 -xN ixC2 . Magnetization, resistivity, and heat capacity measurements demonstrate Ni substitution has a dramatic effect with critical temperature increased up to Tc=12.1 K for x =0.4 Ni concentration, which is a rather high transition temperature for a noncentrosymmetric superconductor. In addition, the unusual superconducting characteristics observed in pure ThCoC2 appear to be suppressed or tuned with Ni substitution towards a more conventional fully gapped superconductor.

3D Magnetic field modeling of a new superconducting synchronous machine using reluctance network method

Science.gov (United States)

Kelouaz, Moussa; Ouazir, Youcef; Hadjout, Larbi; Mezani, Smail; Lubin, Thiery; Berger, Kévin; Lévêque, Jean

2018-05-01

In this paper a new superconducting inductor topology intended for synchronous machine is presented. The studied machine has a standard 3-phase armature and a new kind of 2-poles inductor (claw-pole structure) excited by two coaxial superconducting coils. The air-gap spatial variation of the radial flux density is obtained by inserting a superconducting bulk, which deviates the magnetic field due to the coils. The complex geometry of this inductor usually needs 3D finite elements (FEM) for its analysis. However, to avoid a long computational time inherent to 3D FEM, we propose in this work an alternative modeling, which uses a 3D meshed reluctance network. The results obtained with the developed model are compared to 3D FEM computations as well as to measurements carried out on a laboratory prototype. Finally, a 3D FEM study of the shielding properties of the superconducting screen demonstrates the suitability of using a diamagnetic-like model of the superconducting screen.

Superconducting specific heat jump Δ C ∝ T{sub c}{sup β} (β ∝ 2) and gapless Fermi surfaces in K{sub 1-x}Na{sub x}Fe{sub 2}As{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Grinenko, V.; Efremov, D.V.; Drechsler, S.L.; Aswartham, S.; Gruner, D.; Roslova, M.; Morozov, I.; Nenkov, K.; Wolter, A.U.B. [Leibniz-Institute for Solid State and Materials Research, IFW-Dresden (Germany); Wurmehl, S.; Buechner, B. [Leibniz-Institute for Solid State and Materials Research, IFW-Dresden (Germany); Institut fuer Festkoerperphysik, TU Dresden (Germany); Holzapfel, B. [Leibniz-Institute for Solid State and Materials Research, IFW-Dresden (Germany); Karlsruhe Institute of Technology (KIT), Eggenstein-Leopoldshafen (Germany)

2014-07-01

We present a systematic study of the electronic specific heat jump (Δ C{sub el}) at the superconducting transition temperature T{sub c} of K{sub 1-x}Na{sub x}Fe{sub 2}As{sub 2}. Both T{sub c} and Δ C{sub el} monotonously decrease with increasing x. The jump scales approximately with a novel power-law: Δ C{sub el} ∝ T{sub c}{sup β} with β ∼ 2 determined by the impurity scattering rate. This finding is in sharp contrast to most of all iron-pnictide superconductors with a cubic Bud'ko-Ni-Canfield (BNC) scaling. Our observations, also, suggests that disorder diminishes the small gaps leading to partial gapless superconductivity which results in a large residual Sommerfeld coefficient in the superconducting state for x > 0. Both T-dependence of C{sub el}(T) in the superconducting state and the nearly quadratic scaling of Δ C{sub el} at T{sub c} are well described by the Eliashberg-theory for a single-band d-wave superconductor with weak pair-breaking due to nonmagnetic impurities having reduced the density of superconducting quasi-particles.

High-Tc cuprate superconductivity in a nutshell

International Nuclear Information System (INIS)

Won, Hyekyung; Haas, Stephan; Parker, David; Maki, Kazumi

2005-01-01

Since the discovery of high-T c cuprate superconductivity in 1986 many new experimental techniques and theoretical concepts have been developed. In particular it was shown that the BCS theory of d-wave superconductivity describes semi-quantitatively the high-T c superconductivity. Furthermore, it was demonstrated that Volovik's approach is extremely useful for finding the quasiparticle properties in the vortex state. Here we survey these developments and forecast future directions. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Analysis of mechanical characteristics of superconducting field coil for 17 MW class high temperature superconducting synchronous motor

International Nuclear Information System (INIS)

Kim, J. H.; Park, S. I.; Im, S. H.; Kim, H. M.

2013-01-01

Superconducting field coils using a high-temperature superconducting (HTS) wires with high current density generate high magnetic field of 2 to 5 [T] and electromagnetic force (Lorentz force) acting on the superconducting field coils also become a very strong from the point of view of a mechanical characteristics. Because mechanical stress caused by these powerful electromagnetic force is one of the factors which worsens the critical current performance and structural characteristics of HTS wire, the mechanical stress analysis should be performed when designing the superconducting field coils. In this paper, as part of structural design of superconducting field coils for 17 MW class superconducting ship propulsion motor, mechanical stress acting on the superconducting field coils was analyzed and structural safety was also determined by the coupling analysis system that is consists of commercial electromagnetic field analysis program and structural analysis program.

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

Interplay of antiferromagnetism and superconductivity in cuprates with impurity effect and d-wave pairing

Energy Technology Data Exchange (ETDEWEB)

Mohapatra, Rasmita, E-mail: rmrmmohapatra@gmail.com [P.G. Department of Applied Physics and Ballistics, F.M. University, Balasore, Odisha 756019 (India); Rout, G.C., E-mail: gcr@iopb.res.in [Physics Enclave, Plot no-664/4825, Lane-4A, Shree Vihar, Patia, Bhubaneswar, Odisha 751024 (India)

2015-05-15

Highlights: • We considered here the interplay of antiferromagnetism (AFM) and Superconductivity (SC) with d-wave pairing symmetry in presence of impurity effect. • The tunneling conductance explains the multiple peaks and dip-hump structure. • It is observed that AFM coupling enhances the superconducting transition temperature. • The low temperature specific heat anomaly due to impurity atoms. - Abstract: We present here a model Hamiltonian to study the interplay between staggered magnetic field and the superconductivity with d-wave pairing symmetry in presence of hybridization between impurity f-electrons of rare-earth ions and 3d-electrons of copper ions. The staggered field and superconducting (SC) gaps are calculated by Green’s function technique and solved self-consistently. The coupling constants are compared using s-wave and d-wave pairings. The strength of hybridization suppresses the magnitude of the gaps; while antiferromagnetic coupling enhances the superconducting transition temperature, but suppresses the Neel temperature. The density of states (DOS) representing tunneling conductance shows complex character with impurity level lying at the Fermi level. The electronic specific heat explains prototype heavy fermion behavior in cuprate systems at low temperatures.

Interplay of antiferromagnetism and superconductivity in cuprates with impurity effect and d-wave pairing

International Nuclear Information System (INIS)

Mohapatra, Rasmita; Rout, G.C.

2015-01-01

Highlights: • We considered here the interplay of antiferromagnetism (AFM) and Superconductivity (SC) with d-wave pairing symmetry in presence of impurity effect. • The tunneling conductance explains the multiple peaks and dip-hump structure. • It is observed that AFM coupling enhances the superconducting transition temperature. • The low temperature specific heat anomaly due to impurity atoms. - Abstract: We present here a model Hamiltonian to study the interplay between staggered magnetic field and the superconductivity with d-wave pairing symmetry in presence of hybridization between impurity f-electrons of rare-earth ions and 3d-electrons of copper ions. The staggered field and superconducting (SC) gaps are calculated by Green’s function technique and solved self-consistently. The coupling constants are compared using s-wave and d-wave pairings. The strength of hybridization suppresses the magnitude of the gaps; while antiferromagnetic coupling enhances the superconducting transition temperature, but suppresses the Neel temperature. The density of states (DOS) representing tunneling conductance shows complex character with impurity level lying at the Fermi level. The electronic specific heat explains prototype heavy fermion behavior in cuprate systems at low temperatures

Overview of superconductivity in Japan - Strategy road map and R and D status

International Nuclear Information System (INIS)

Tsukamoto, O.

2008-01-01

Superconducting technology benefits society in broad fields; environment/energy, life science, manufacturing industry and information and communication. Superconducting equipments and devices used in various fields are divided into two categories, electric and electronic applications. Technologies in those applications are progressing remarkably owing to firm and consistent supports by various national projects. The final target of the NEDO R and D project of fundamental technology for superconductivity applications to develop 500 m long coated conductors (CCs) of the critical current 300 A/cm (at 77 K, 0 T) will be fulfilled by the end of JFY 2007 and manufacturing process to produce extremely low-cost CCs is to be developed to make the applications realistic. Preliminary works to develop power apparatuses using CCs have started in the frame of the R and D project for the fundamental technology and have produced significant results. Performance of BSCCO/Ag-sheathed wires has been improved greatly and various applications using those wires are being developed. R and D projects for SMES, power cable, flywheel energy storage and rotating machines are going to introduce those equipments to the real world. Technologies of SQUID and SFQ, basic devices of the electronic applications, are progressing dramatically also owing to various national projects. In this back ground the technology strategy map in the field of superconducting technology was formulated to prioritize investments in R and D by clearly defining the objectives and inspire autonomous R and D actives in various fields of industries. R and D activities in the superconducting technologies are to be scheduled following this strategy map

Superconductivity in multilayer perovskite. Weak coupling analysis

International Nuclear Information System (INIS)

Koikegami, Shigeru; Yanagisawa, Takashi

2006-01-01

We investigate the superconductivity of a three-dimensional d-p model with a multilayer perovskite structure on the basis of the second-order perturbation theory within the weak coupling framework. Our model has been designed with multilayer high-T c superconducting cuprates in mind. In our model, multiple Fermi surfaces appear, and the component of a superconducting gap function develops on each band. We have found that the multilayer structure can stabilize the superconductivity in a wide doping range. (author)

Evidence for unconventional d-wave superconducting state in CeCu{sub 2}Si{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Vieyra, Hugo A.; Geibel, Christoph; Steglich, Frank; Oeschler, Niels [Max-Planck-Institute for Chemical Physics of Solids, Dresden 01187 (Germany); Parker, David [US Naval Research Laboratory, Washington, DC 20375 (United States); Jeevan, Hirale S. [I. Physik. Institut, Georg-August-Universitaet Goettingen, Goettingen 37077 (Germany)

2010-07-01

The heavy-fermion CeCu{sub 2}Si{sub 2} represents a prime system to study unconventional superconductivity in the vicinity of a magnetic instability. Within the homogeneity range of pure CeCu{sub 2}Si{sub 2} different ground states can be obtained. S-type crystals exhibit a superconducting transition at T{sub c}=0.6 K, whereas A/S-type show in addition antiferromagnetic order at T{sub N}=0.8 K. In recent years, the synthesis techniques have been optimized in order to obtain large high-quality single crystals with well defined ground state properties. This allows the systematic study of the superconducting order parameter and its variation at the border with magnetic order. In this work, we present angular dependent resistivity measurements on high-quality S- and A/S-type single-crystalline CeCu{sub 2}Si{sub 2} samples. The experimental results for the angular dependence of the upper critical field B{sub c2} as well as theoretical calculations taking into account effects like the strong Pauli paramagnetism, hint towards an unconventional d-wave symmetry of the order parameter in CeCu{sub 2}Si{sub 2}.

Stabilized superconducting materials and fabrication process. Materiaux supraconducteurs stabilises et leur procede d'obtention

Energy Technology Data Exchange (ETDEWEB)

Chevallier, B; Dance, J M; Etourneau, J; Lozano, L; Tressaud, A; Tournier, R; Sulpice, A; Chaussy, J; Lejay, P

1989-10-06

Superconducting ceramics are fluorinated at a temperature {le} 120{sup 0}C. Are also claimed new superconducting materials with a fluorine concentration gradient decreasing from the surface to the core. Superconductivity is stabilized and/or improved.

Potential damage to dc superconducting magnets due to high frequency electromagnetic waves

Science.gov (United States)

Gabriel, G. J.; Burkhart, J. A.

1977-01-01

Studies of a d.c. superconducting magnet coil indicate that the large coil behaves as a straight waveguide structure. Voltages between layers within the coil sometimes exceeded those recorded at terminals where protective resistors are located. Protection of magnet coils against these excessive voltages could be accomplished by impedance matching throughout the coil system. The wave phenomenon associated with superconducting magnetic coils may create an instability capable of converting the energy of a quiescent d.c. superconducting coil into dissipative a.c. energy, even in cases when dielectric breakdown does not take place.

Structural, electronic, superconducting and mechanical properties of ReC and TcC

Energy Technology Data Exchange (ETDEWEB)

Kavitha, M.; Priyanga, G. Sudha; Rajeswarapalanichamy, R., E-mail: rajeswarapalanichamy@gmail.com; Santhosh, M. [Department of Physics, N.M.S.S.V.N College, Madurai, Tamilnadu-625019 (India)

2015-06-24

The structural, electronic, superconducting and mechanical properties of ReC and TcC are investigated using density functional theory calculations. The lattice constants, bulk modulus, and the density of states are obtained. The calculated lattice parameters are in good agreement with the available results. The density of states reveals that ReC and TcC exhibit metallic behavior at ambient condition. A pressure-induced structural phase transition is observed in both materials.

Methodology and search for superconductivity in the La-Si-C system

International Nuclear Information System (INIS)

De la Venta, J; Basaran, Ali C; Schuller, Ivan K; Grant, T; Machado, A J S; Fisk, Z; Suchomel, M R; Weber, R T

2011-01-01

In this paper we describe a methodology for the search for new superconducting materials. This consists of a parallel synthesis of a highly inhomogeneous alloy which covers large areas of the metallurgical phase diagram combined with a fast, microwave-based method which allows non-superconducting portions of the sample to be discarded. Once an inhomogeneous sample containing a minority phase superconductor is identified, we revert to well-known thorough identification methods which include standard physical and structural methods. We show how a systematic structural study helps in avoiding misidentification of new superconducting materials when there are indications from other methods of new discoveries. These ideas are applied to the La-Si-C system which exhibits promising normal state properties which are sometimes correlated with superconductivity. Although this system shows indications for the presence of a new superconducting compound, the careful analysis described here shows that the superconductivity in this system can be attributed to intermediate binary and single phases of the system.

Mechanism of high-T{sub c} superconductivity studied by neutron scattering

Energy Technology Data Exchange (ETDEWEB)

Yamada, Kazuyoshi [Tohoku Univ., Sendai (Japan). Faculty of Science

1998-03-01

La{sub 2-x}Sr{sub x}CuO{sub 4} is one of the typical high-T{sub c} cuprates where Sr-doping creates many phases from the Mott insulator at x=0 nonsuperconducting metal for x>0.26; the high-T{sub c} superconductivity appears for 0.06{<=}x{<=}0.26. We have grown large single crystals of La{sub 2-x}Sr{sub x}CuO{sub 4} over a wide the doping rate up to x=0.3 and performed systematic neutron scattering experiments for the first time. We obtained several results indicating an intimate relation between the dynamical spin correlations and the superconductivity. Incommensurate spatial modulation appears in the antiferromagnetic spin correlations beyond x=0.05 close to the lower boundary of the superconducting phase. We found that the degree of the spatial modulation or the incommensurability {delta} increases with doping and T{sub c} is linearly scaled with {delta} for x{<=}0.15. A well-defined spin excitation gap was observed only for x=0.15 where the T{sub c} reaches the maximum value. And the dynamical spin coherence degrades upon doping with x>>0.15. There results strongly suggest the essential role of the magnetically correlated region and the spatial spin modulation in the CuO{sub 2} planes to sustain or create the superconductivity. (author)

Deposition of superconducting (Cu, C)-Ba-O films by pulsed laser deposition at moderate temperature

International Nuclear Information System (INIS)

Yamamoto, Tetsuro; Kikunaga, Kazuya; Obara, Kozo; Terada, Norio; Kikuchi, Naoto; Tanaka, Yasumoto; Tokiwa, Kazuyasu; Watanabe, Tsuneo; Sundaresan, Athinarayanan; Shipra

2007-01-01

Superconducting (Cu, C)-Ba-O thin films have been epitaxially grown on (100) SrTiO 3 at a low growth temperature of 500-600 deg. C by pulsed laser deposition. The dependences of their crystallinity and transport properties on preparation conditions have been investigated in order to clarify the dominant parameters for carbon incorporation and the emergence of superconductivity. It has been revealed that the CO 3 content in the films increases with increasing both the parameters of partial pressure of CO 2 during film growth and those of growth rate and enhancement of superconducting properties. The present study has also revealed that the structural and superconducting properties of the (Cu, C)-Ba-O films are seriously deteriorated by the irradiation of energetic particles during deposition. Suppression of the radiation damage is another key for a high and uniform superconducting transition. By these optimizations, a superconducting onset temperature above 50 K and a zero-resistance temperature above 40 K have been realized

1D goes 2D: A Berezinskii-Kosterlitz-Thouless transition in superconducting arrays of 4-Angstrom carbon nanotubes

KAUST Repository

Wang, Zhe

2010-10-01

We report superconducting resistive transition characteristics for array(s) of coupled 4-Angstrom single wall carbon nanotubes embedded in aluminophosphate-five zeolite. The transition was observed to initiate at 15 K with a slow resistance decrease switching to a sharp, order of magnitude drop between 7.5 and 6.0 K with strong (anisotropic) magnetic field dependence. Both the sharp resistance drop and its attendant nonlinear IV characteristics are consistent with the manifestations of a Berezinskii-Kosterlitz-Thouless transition that establishes quasi long range order in the plane transverse to the c-axis of the nanotubes, leading to an inhomogeneous system comprising 3D superconducting regions connected by weak links. Global coherence is established at below 5 K with the appearance of a well-defined supercurrent gap/low resistance region at 2 K. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Antiferromagnetism and d-wave superconductivity in (doped) Mott insulators: A wave function approach

OpenAIRE

Weng, Z. Y.; Zhou, Y.; Muthukumar, V. N.

2003-01-01

We propose a class of wave functions that provide a unified description of antiferromagnetism and d-wave superconductivity in (doped) Mott insulators. The wave function has a Jastrow form and prohibits double occupancies. In the absence of holes, the wave function describes antiferromagnetism accurately. Off diagonal long range order develops at finite doping and the superconducting order parameter has d-wave symmetry. We also show how nodal quasiparticles and neutral spin excitations can be ...

3D integrated superconducting qubits

Science.gov (United States)

Rosenberg, D.; Kim, D.; Das, R.; Yost, D.; Gustavsson, S.; Hover, D.; Krantz, P.; Melville, A.; Racz, L.; Samach, G. O.; Weber, S. J.; Yan, F.; Yoder, J. L.; Kerman, A. J.; Oliver, W. D.

2017-10-01

As the field of quantum computing advances from the few-qubit stage to larger-scale processors, qubit addressability and extensibility will necessitate the use of 3D integration and packaging. While 3D integration is well-developed for commercial electronics, relatively little work has been performed to determine its compatibility with high-coherence solid-state qubits. Of particular concern, qubit coherence times can be suppressed by the requisite processing steps and close proximity of another chip. In this work, we use a flip-chip process to bond a chip with superconducting flux qubits to another chip containing structures for qubit readout and control. We demonstrate that high qubit coherence (T1, T2,echo > 20 μs) is maintained in a flip-chip geometry in the presence of galvanic, capacitive, and inductive coupling between the chips.

High-$T_c$ superconductivity by phase cloning

CERN Document Server

Ilieva, N; Ilieva, Nevena; Thirring, Walter

2007-01-01

We consider a BCS-type model in the spin formalism and argue that the structure of the interaction provides a mechanism for control over directions of the spin $\\vect S$ other than $S_z$, which is being controlled via the conventional chemical potential. We also find the conditions for the appearance of a high-$T_c$ superconducting phase.

d-wave superconductivity in the frustrated two-dimensional periodic Anderson model

Directory of Open Access Journals (Sweden)

Wei Wu

2015-02-01

Full Text Available Superconductivity in heavy-fermion materials can sometimes appear in the incoherent regime and in proximity to an antiferromagnetic quantum critical point. Here, we study these phenomena using large-scale determinant quantum Monte Carlo simulations and the dynamical cluster approximation with various impurity solvers for the periodic Anderson model with frustrated hybridization. We obtain solid evidence for a d_{x^{2}−y^{2}} superconducting phase arising from an incoherent normal state in the vicinity of an antiferromagnetic quantum critical point. There is a coexistence region, and the width of the superconducting dome increases with frustration. Through a study of the pairing dynamics, we find that the retarded spin fluctuations give the main contribution to the pairing glue. These results are relevant for unconventional superconductivity in the Ce-115 family of heavy fermions.

D-Zero Superconducting Soleniod RTD Instrumentation Readings Upon Receipt at Fermilab

International Nuclear Information System (INIS)

Markley, D.

1998-01-01

This engineering note documents the Dzero Superconducting Solenoid Platinum RTD, Carbon Glass RTD, and Helium level gage instrumentation values upon receipt at Fermilab. This note is concerned with the internal instrumentation, the external instrumentation can easily be repaired if any problems arise. The Solenoid was Purchased from Toshiba and shipped from the Kehin Works in Japan. The Solenoid was received at Dzero May 12, 1997. The Solenoid was shipped in three large components. They are the Solenoid, Control Dewar, and Chimney. There are 2 main instrumentation port areas where all the internal instrumentation is available to the outside world. These 2 places are the top of the Control Dewar and the North end of the Solenoid. These two instrumentation feedthrough area's have Cyocera hermetic feedthrough port connectors welded into place. The Cyocera connector can and does mate with the Burndy Bantom cable end connector of the same pin/socket number. Since the Hermetic feedthrough and cable connector are different manufacturers, the pin layout pattern is not the same. The Toshiba drawings show both manufacturers pin numbers. The Dzero engineering notes show only the Burndy pin numbers.

Disappearance of superconductivity and critical resistance in thin indium films

International Nuclear Information System (INIS)

Okuma, Satoshi; Nishida, Nobuhiko

1991-01-01

In thin granular films composed of two-dimensionally coupled indium particles, we have studied influences of average particle sizes anti d on the superconducting transition. For films with anti d=280A and 224A, superconducting transition temperature stays almost constant with increasing the sheet resistance R n in the normal state, while for a film with anti d=140A, it decreases linearly with R n . This means that the system changes to a dirty superconductor by reducing anti d. With further increasing R n , superconductivity disappears when R n exceeds the value R c of order h/4e 2 , which seems to correlate with anti d. (orig.)

Structural stability, electronic, mechanical and superconducting properties of CrC and MoC

Energy Technology Data Exchange (ETDEWEB)

Kavitha, M.; Sudha Priyanga, G. [Department of Physics, N.M.S.S.V.N College, Madurai 625019, Tamilnadu (India); Rajeswarapalanichamy, R., E-mail: rrpalanichamy@gmail.com [Department of Physics, N.M.S.S.V.N College, Madurai 625019, Tamilnadu (India); Iyakutti, K. [Department of Physics and Nanotechnology, SRM University, Chennai 603203, Tamilnadu (India)

2016-02-01

The structural, electronic, mechanical and superconducting properties of chromium carbide (CrC) and molybdenum carbide (MoC) are investigated using first principles calculations based on density functional theory (DFT). The computed ground state properties like equilibrium lattice constants and cell volume are in good agreement with available theoretical and experimental data. A pressure induced structural phase transition from tungsten carbide phase (WC) to zinc blende phase (ZB) and then zinc blende phase (ZB) to nickel arsenide phase (NiAs) are observed in both chromium and molybdenum carbides. Electronic structure reveals that these carbides are metallic at ambient condition. All the calculated elastic constants obey the Born–Huang stability criteria, suggesting that they are mechanically stable at normal and high pressure. The super conducting transition temperatures for CrC and MoC in WC phase are found to be 31.12 K and 17.14 K respectively at normal pressure. - Highlights: • Electronic and mechanical properties of CrC and MoC are investigated. • Pressure induced structural phase transition is predicted at high pressure. • Electronic structure reveals that these materials exhibit metallic behaviour. • Debye temperature values are computed for CrC and MoC. • Superconducting transition temperature values are computed.

Superconductivity in Mesocrystalline Inverse Opal Structures

Science.gov (United States)

Lungu, Anca; Bleiweiss, Michael; Saygi, Salih; Amirzadeh, Jafar; Datta, Timir

2000-03-01

Mesocrystalline inverse opal structures were fabricated by the electrodeposition of metallic lead in synthetic opals. In these structures, the superconducting regions percolate in all directions through the voids in the artificial opals and their size is comparable to the coherence length for bulk lead. The inverse lead opals were proven superconducting, with a transition temperature close to that of bulk lead (between 7.2 K and 7.36 K) and broad transition regions. The magnetic behavior of the inverse opals was very different from that of bulk lead. Due to the reduced dimensonality of the superconducting regions, not surprisingly, the magnetic properties of our samples were found to be similar to those of type II superconductors. The critical magnetic field (or the field at which T_copals was proven at least two times larger than that for bulk lead and (dT_c/dH) was observed 2.7 times smaller. We found a reversible ZFC-FC magnetic behavior in the temperature range between T* and T_c. We also performed magnetic relaxation measurements and studied the fluctuation diamagnetism above T_c.

On the 22-23 K superconducting phase in the Y-Pd-B-C system

International Nuclear Information System (INIS)

Tominez, E.; Alleno, E.; Decamps, B.; Schiffmacher, G.; Godart, C.; Berger, P.; Bohn, M.

1998-01-01

Superconducting and non-superconducting (annealed) samples of YPd 5 B 3 C 0.35 have been investigated using electrical resistance and magnetization measurements, X-ray diffraction, electron diffraction with energy dispersive X-ray spectrometry and electron probe micro analysis (EPMA). In the superconducting sample, six phases were observed out of which two were clearly decomposed by annealing. Composition and unit cell of these phases were determined. The concentrations of boron and carbon are uncertain, due to the small atomic weight of these elements. Therefore, we report for the first time, nuclear probe micro analysis (NPMA) measurements. Preliminary results of NPMA are consistent with EPMA. At last, we suggest that the superconducting phase has a composition close to YPd 2 B 2 C and an I-centred tetragonal unit cell with a=3.751(1) and c=10.725(3) A. (orig.)

Superconductivity in the periodic Anderson model with anisotropic hybridization

International Nuclear Information System (INIS)

Sarasua, L.G.; Continentino, Mucio A.

2003-01-01

In this work we study superconductivity in the periodic Anderson model with both on-site and intersite hybridization, including the interband Coulomb repulsion. We show that the presence of the intersite hybridization together with the on-site hybridization significantly affects the superconducting properties of the system. The symmetry of the hybridization has a strong influence in the symmetry of the superconducting order parameter of the ground state. The interband Coulomb repulsion may increase or decrease the superconducting critical temperature at small values of this interaction, while is detrimental to superconductivity for strong values. We show that the present model can give rise to positive or negative values of dT c /dP, depending on the values of the system parameters

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

Effect of He pressure on the superconducting transition temperatures of Na2CsC60 and (NH3)4Na2CsC60

International Nuclear Information System (INIS)

Schirber, J.E.; Bayless, W.R.; Rosseinsky, M.J.; Zhou, O.; Fleming, R.M.; Murphy, D.; Fischer, J.E.

1994-01-01

The Na based mixed alkali doped C 60 superconductors show anomalous behavior with respect to the ''universal'' superconducting transition temperature T c vs lattice constant a 0 relation followed by most of the fcc A 3 C 60 superconductors. We have measured dt c /dP for Na 2 CsC 60 and (NH 3 ) 4 Na 2 CsC 60 using solid He as the pressure medium to ∼ 6 kbar finding dT c /dP equal to -0.8±(0.01) K/kbar and -1.0(±0.1)K/kbar for Na 2 CsC 60 and Na 2 (NH 3 ) 4 C 60 respectively. Our value for Na 2 CsC 60 differs markedly from that obtained by Mizuki et al of about -1.3 K/kbar. However, using N 2 or Ar, we obtain values for dT c /dP in substantial agreement with Mizuki et al who used fluorinert to generate their pressure. This work emphasizes the need for compressibility measurements with the same pressure medium in the appropriate temperature range so that meaningful comparisons can be made between various pressure measurements and models which are based on lattic spacing

Possible high-T/sub c/ superconductivity in thin wires

International Nuclear Information System (INIS)

Lee, Y.C.; Mendoza, B.S.

1989-01-01

A heuristic approach to the theory of superconductivity based on a simple physical picture and capable of treating the simultaneous participation of multiple bosonic modes that mediate the pairing interaction is first developed. The effect of the bosonic mode damping is also accounted for. We then propose a possible mechanism of superconductivity in slender electronic systems of finite cross sections based on the pairing interaction mediated by the multiple modes of acoustic plasmons in these structures. Such modes include the quasi-one-dimensional plasmon as well as the so-called slender acoustic plasmons. The critical temperature and the energy gap/T/sub c/ ratio are then calculated by the heuristic method just developed. Numerical results on T/sub c/ in various samples are presented, showing T/sub c/ in the 150--200 K range. The ratio 2Δ 0 /T/sub c/ differs generally from the BCS value due to the temperature dependence of the mode damping. The associated coherence length is shown to be considerably smaller than the transverse dimension of the wires

D-day on board a tank landing ship: meat, cheese and blood transfusion.

Science.gov (United States)

Demetriades, A K; Gavalas, M C; Ryan, J

2008-03-01

Tank Landing Ships were used as evacuation station hospitals during D-Day of World War Two. This historical vignette describes how difficulties were overcome in blood transfusion and trauma surgery aboard these ships. Their place in the evacuation chain is discussed in relation to previous experiences in military medicine.

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 (K_xC₆₀NWs, while the superconducting volume fractions changed with x. The highest shielding fraction of a full shielding volume was observed in the material of K_3.3C₆₀NW 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 K_xC₆₀NWs in comparison to those of K_xC₆₀ crystals, which show superconductivity at 19 K in K₃C₆₀. The lattice structures are also discussed, based on the x-ray diffraction (XRD analyses.

Nonphonon mechanism of superconductivity in compounds of transition metals

International Nuclear Information System (INIS)

Ivanov, V.A.; Zaitsev, R.O.

1989-01-01

The kinematical mechanism of superconductivity is applied to the Emery-Hirsch model for the CuO 2 and BiO 3 layers. A superconducting region due to strong kinematic interaction of p- and s, d-electrons are determined as a function of n p and n s,d -degrees of non-filling of 2p 6 ,6s 2 ,3d 10 shells of O 2 - ,Bi 3 + ,Cu + . The T c is calculated taking into account the spin flip relaxation time. Magnetostatic properties of a superconducting state in a weak magnetic field are investigated. Coefficients of the Ginzburg-Landau equation are calculated. The ground state energy of the Emery-Hirsch model is also calculated

A.c. susceptibility measurements in the presence of d.c. magnetic fields for Nd-Ba-Cu-O superconductors

International Nuclear Information System (INIS)

Watahiki, M.; Murakami, M.; Yoo, S.I.

1997-01-01

We report the temperature and magnetic field dependence of the complex a.c. susceptibility with bias d.c. magnetic fields for melt-processed Nd-Ba-Cu-O superconductor. The onset temperature (T onset ) of the real part of a.c. susceptibility shifted to a lower temperature with increasing d.c. magnetic field. The superconducting transition temperature (T c ) determined by d.c. magnetization measurements did not shift appreciably to a lower-temperature region with increasing d.c. magnetic field. The distinction between T onset and T c indicates that the a.c. susceptibility measurements detect the energy dissipation generated by the motion of flux lines. We have also measured flux profiles and found that there was no appreciable change in flux penetration below and above the peak field, which suggests that the peak effect in Nd-Ba-Cu-O is not due to the phase transition in the flux line lattice. (author)

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.

Conventional superconductivity at 203 K at high pressures

Energy Technology Data Exchange (ETDEWEB)

Drozdov, Alexander; Eremets, Mikhail; Troyan, Ivan [Max-Planck-Institut fuer Chemie, Hahn-Meitner-Weg 1, 55128 Mainz (Germany); Ksenofontov, Vadim; Shylin, Sergii [Institut fuer Anorganische Chemie und Analytische Chemie, Johannes Gutenberg-Universitet Mainz, Staudingerweg 9, 55099 Mainz (Germany)

2016-07-01

A search for high, room temperature conventional superconductivity is promising as the Bardeen-Cooper-Schrieffer (BCS) theory in the Eliashberg formulation puts no apparent limits on T{sub c}. Materials with light elements are especially favorable as they provide high frequencies in the phonon spectrum. However only a moderately high T{sub c} = 39 K has been found in this search in MgB{sub 2}. We systematically studied metallic hydrogen and covalent hydrogen dominant compounds and found the record T{sub c} of 203 K at pressure 140 GPa in sulfur hydride. We proved occurrence of superconductivity by the sharp drop of the resistivity to zero; the decrease of T{sub c} with magnetic field; the pronounce isotope shift of T{sub c} in D{sub 2}S which evidences of a major role of phonons in the superconductivity; and the magnetic susceptibility measurements. The X-ray diffraction data confirmed that the superconductive phase has the predicted bcc structure. This phase can be considered as an atomic hydrogen superconductor stabilized by sulfur.

The Future of Superconducting Technology for Particle Accelerators

CERN Document Server

Yamamoto, Akira

2015-01-01

Introduction: - Colliders constructed and operated - Future High Energy Colliders under Study - Superconducting Phases and Applications - Possible Choices among SC Materials Superconducting Magnets and the Future - Advances in SC Magnets for Accelerators - Nb$_{3}$Sn for realizing Higher Field - NbTi to Nb$_{3}$Sn for realizing High Field (> 10 T) - HL-LHC as a critical milestone for the Future of Acc. Magnet Technology - Nb$_{3}$Sn Superconducting Magnets (> 11 T)and MgB2 SC Links for HL-LHC - HL-LHC, 11T Dipole Magnet - Nb$_{3}$Sn Quadrupole (MQXF) at IR - Future Circular Collider Study - Conductor development (1998-2008) - Nb$_{3}$Sn conductor program - 16 T Dipole Options and R&D sharing - Design Study and Develoment for SppC in China - High-Field Superconductor and Magnets - HTS Block Coil R&D for 20 T - Canted Cosine Theta (CCT) Coil suitable with Brittle HTS Conductor - A topic at KEK: S-KEKB IRQs just integrated w/ BELLE-II ! Superconducting RF and the Future - Superconducting Phase...

The Future of Superconducting Technology for Particle Accelerators

CERN Document Server

Yamamoto, Akira

2015-01-01

Introduction: - Colliders constructed and operated - Future High Energy Colliders under Study - Superconducting Phases and Applications - Possible Choices among SC Materials Superconducting Magnets and the Future - Advances in SC Magnets for Accelerators - Nb3Sn for realizing Higher Field - NbTi to Nb3Sn for realizing High Field (> 10 T) - HL-LHC as a critical milestone for the Future of Acc. Magnet Technology - Nb3Sn Superconducting Magnets (> 11 T)and MgB2 SC Links for HL-LHC - HL-LHC, 11T Dipole Magnet - Nb3Sn Quadrupole (MQXF) at IR - Future Circular Collider Study - Conductor development (1998-2008) - Nb3Sn conductor program - 16 T Dipole Options and R&D sharing - Design Study and Develoment for SppC in China - High-Field Superconductor and Magnets - HTS Block Coil R&D for 20 T - Canted Cosine Theta (CCT) Coil suitable with Brittle HTS Conductor - A topic at KEK: S-KEKB IRQs just integrated w/ BELLE-II ! Superconducting RF and the Future - Superconducting Phases and Applications - Poss...

46 CFR 153.909 - Completing the Cargo Record Book and record retention: Categories A, B, C, and D.

Science.gov (United States)

2010-10-01

... on board and readily available for inspection and copying by the Coast Guard and when the ship is a U... (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SHIPS CARRYING BULK LIQUID, LIQUEFIED GAS, OR COMPRESSED GAS... and record retention: Categories A, B, C, and D. (a) The person in charge of a ship shall ensure that...

SURVEYING, MODELING AND 3D REPRESENTATION OF A WRECK FOR DIVING PURPOSES: CARGO SHIP “VERA”

OpenAIRE

Ktistis, A.; Tokmakidis, P.; Papadimitriou, K.

2017-01-01

This paper presents the results from an underwater recording of the stern part of a contemporary cargo-ship wreck. The aim of this survey was to create 3D representations of this wreck mainly for recreational diving purposes. The key points of this paper are: a) the implementation of the underwater recording at a diving site; b) the reconstruction of a 3d model from data that have been captured by recreational divers; and c) the development of a set of products to be used by the general publi...

Antiferromagnetic and superconducting gaps and their interrelation in high-T sub c cuprates

CERN Document Server

Arrigoni, E; Eckl, T; Hanke, W

2003-01-01

We propose a phenomenological model, comprising a microscopic SO(5) model plus the on-site Hubbard interaction U (projected SO(5) model) to understand the interrelation between the d-wave-gap modulation observed by recent angle-resolved photoemission experiments in the insulating antiferromagnet Ca sub 2 CuO sub 2 Cl sub 2 and the d-wave gap of high-T sub c superconducting materials. The on-site interaction U is important in order to produce a Mott gap of the correct order of magnitude, which would be absent in an exact SO(5) theory. The projected SO(5)-model explains the gap characteristics, namely both the symmetry and the different order of magnitude of the gap modulations between the AF and the SCc phases. Furthermore, it is shown that the projected SO(5) theory can provide an explanation for a recent observation [E. Pavarini et al., Phys. Rev. Lett. 87, 47003 (2001)], i. e. that the maximum T sub c observed in a large variety of high-T sub c cuprates scales with the next-nearest-neighbor hopping matrix e...

Theory of high-T sub c superconductivity based on the fermion-condensation quantum phase transition

CERN Document Server

Amusia, M Ya; Shaginyan, V R

2001-01-01

A theory of high temperature superconductivity based on the combination of the fermion-condensation quantum phase transition and the conventional theory of superconductivity is presented. This theory describes maximum values of the superconducting gap which can be as big as DELTA sub 1 approx 0.1 epsilon sub F , with epsilon sub F being the Fermi level. It is shown that the critical temperature 2T sub c approx = DELTA sub 1. If there exists the pseudogap above T sub c then 2T* approx = DELTA sub 1 , and T* is the temperature at which the pseudogap vanished. A discontinuity in the specific heat at T sub c is calculated. The transition from conventional superconductors to high-T sub c ones as a function of the doping level is investigated

Race-track coils for a 3 MW HTS ship motor

Energy Technology Data Exchange (ETDEWEB)

Ueno, E., E-mail: ueno-eisaku@sei.co.jp; Kato, T.; Hayashi, K.

2014-09-15

Highlights: • Sumitomo Electric manufactured the HTS field coils for a 3 MW HTS ship motor. • The motor was developed and successfully passed the loading test by Kawasaki Heavy. • We tested and obtained the basic data to evaluate the 20-year durability of coils. - Abstract: Since the discovery of high-temperature superconductivity (HTS), Sumitomo Electric has been developing silver-sheathed Bi2223 superconducting wire and products. Ship propulsion motors are one of the most promising applications of HTS. Sumitomo Electric Industries, Ltd. (SEI) has recently manufactured 24 large racetrack coils, using 70 km long DI-BSCCO wires, for use in a 3 MW HTS motor developed by Kawasaki Heavy Industries, Ltd. (KHI). The 3 MW HTS motor, using our newly developed racetrack coils, has successfully passed the loading test. It is particularly important that the HTS field coils used in ship propulsion motors can withstand the expansive forces repeatedly applied to them. As racetrack type coils have straight sections, the support mechanism they require to withstand expansive forces is very different from that of circular coils. Therefore, we ran tests and obtained the basic data to evaluate the 20-year durability of racetrack coils against the repeatedly applied expansive forces expected in domestic ship propulsion motors.

Coexistence of superconductivity and density waves in quasi-two-dimensional metals

Energy Technology Data Exchange (ETDEWEB)

Ismer, Jan-Peter

2011-06-03

This dissertation deals with the high-temperature superconductivity in the hole- and electron-doped copper superconductors. In the first part, superconducting phases are investigated on a background of different types of density waves. Singlet superconductivity is studied with s- and d-wave symmetry on a background of spin, charge or D-density waves with respect to stability as well as phase structure and impulse dependence of the gap function. In the second part, the dynamic spin susceptibility for different phases is calculated and compared with experimental data extracted from results of inelastic neutron scattering experiments. The observed phases are d-wave superconductivity, D-density wave, and coexistence of the two. For d-wave superconductivity, the influence of a magnetic field parallel to the copper oxide layer and the temperature development of the susceptibility when for T >> T{sub c} a spin density wave phase is present are investigated. [German] Diese Dissertation beschaeftigt sich mit der Hochtemperatursupraleitung in den loch- und elektron-dotierten Kuprat-Supraleitern. Im ersten Teil der Arbeit werden supraleitende Phasen auf einem Hintergrund verschiedener Typen von Dichtewellen untersucht. Es wird Singlett-Supraleitung mit s- und d-Wellen-Symmetrie auf einem Hintergrund von Spin-, Ladungs- oder D-Dichtewelle hinsichtlich Stabilitaet sowie Phasenstruktur und Impulsabhaengigkeit der Gapfunktion untersucht. Im zweiten Teil wird die dynamische Spinsuszeptibilitaet fuer verschiedene Phasen berechnet und mit experimentellen Daten verglichen, die aus Ergebnissen von Inelastischen Neutronenstreuungsexperimenten extrahiert wurden. Die betrachteten Phasen sind d-Wellen-Supraleitung, D-Dichtewelle und Koexistenz der beiden. Fuer d-Wellen-Supraleitung werden der Einfluss eines Magnetfelds parallel zur Kupferoxidschicht und die Temperaturentwicklung der Suszeptibilitaet, wenn fuer T >> T{sub c} eine Spin-Dichtewelle-Phase vorliegt, untersucht.

Fraunhofer regime of operation for superconducting quantum interference filters

DEFF Research Database (Denmark)

Shadrin, A.V.; Constantinian, K.Y.; Ovsyannikov, G.A.

2008-01-01

Series arrays of superconducting quantum interference devices (SQUIDs) with incommensurate loop areas, so-called superconducting quantum interference filters (SQIFs), are investigated in the kilohertz and the gigahertz frequency range. In SQIFs made of high-T-c bicrystal junctions the flux...... range of more than 60 dB in the kilohertz range. In the 1-2 GHz range the estimated power gain is 20 dB and the magnetic flux noise level is as low as 10(-4)Phi(0)....

Competition between disorder and exchange splitting in superconducting ZrZn sub 2

CERN Document Server

Powell, B J; Györffy, B L

2003-01-01

We propose a simple picture for the occurrence of superconductivity and the pressure dependence of the superconducting critical temperature, T sub S sub C , in ZrZn sub 2. According to our hypothesis the pairing potential is independent of pressure, but the exchange splitting, E sub x sub c , leads to a pressure dependence in the (spin dependent) density of states at the Fermi level, D subsigma (epsilon sub F). Assuming p-wave pairing T sub S sub C is dependent on D subsigma (epsilon sub F) which ensures that, in the absence of non-magnetic impurities, T sub S sub C decreases as pressure is applied until it reaches a minimum in the paramagnetic state. Disorder reduces this minimum to zero, this gives the illusion that the superconductivity disappears at the same pressure as ferromagnetism does. (letter to the editor)

Compact superconducting cyclotron C400 for hadron therapy

Energy Technology Data Exchange (ETDEWEB)

Jongen, Y.; Abs, M.; Blondin, A.; Kleeven, W.; Zaremba, S.; Vandeplassche, D. [IBA, Chemin du Cyclotron 3, B-1348 Louvain-la-Neuve (Belgium); Aleksandrov, V.; Gursky, S.; Karamyshev, O. [JINR, Joliot-Curie 6, 141980 Dubna, Moscow region (Russian Federation); Karamysheva, G., E-mail: gkaram@nu.jinr.r [JINR, Joliot-Curie 6, 141980 Dubna, Moscow region (Russian Federation); Kazarinov, N.; Kostromin, S.; Morozov, N.; Samsonov, E.; Shirkov, G.; Shevtsov, V.; Syresin, E.; Tuzikov, A. [JINR, Joliot-Curie 6, 141980 Dubna, Moscow region (Russian Federation)

2010-12-01

The compact superconducting isochronous cyclotron C400 has been designed by the IBA-JINR collaboration. It will be the first cyclotron in the world capable of delivering protons, carbon and helium ions for cancer treatment. The cyclotron construction is started this year within the framework of the Archade project (Caen, France). {sup 12}C{sup 6+} and {sup 4}He{sup 2+} ions will be accelerated to 400 MeV/uu energy and extracted by the electrostatic deflector, H{sub 2}{sup +} ions will be accelerated to the energy of 265 MeV/uu and extracted by stripping. The magnet yoke has a diameter of 6.6 m, the total weight of the magnet is about 700 t. The designed magnetic field corresponds to 4.5 T in the hills and 2.45 T in the valleys. Superconducting coils will be enclosed in a cryostat; all other parts of the cyclotron will be warm. Three external ion sources will be mounted on the switching magnet on the injection line located below the cyclotron. The main parameters of the cyclotron, its design, the current status of the development work on the cyclotron systems are presented.

Theoretical studies of superconductivity in doped BaCoSO

Science.gov (United States)

Qin, Shengshan; Li, Yinxiang; Zhang, Qiang; Le, Congcong; Hu, Jiangping

2018-06-01

We investigate superconductivity that may exist in the doped BaCoSO, a multi-orbital Mott insulator with a strong antiferromagnetic ground state. The superconductivity is studied in both t-J type and Hubbard type multi-orbital models by mean field approach and random phase approximation (RPA) analysis. Even if there is no C 4 rotational symmetry, it is found that the system still carries a d-wave like pairing symmetry state with gapless nodes and sign changed superconducting order parameters on Fermi surfaces. The results are largely doping insensitive. In this superconducting state, the three {t_{{2_g}}} orbitals have very different superconducting form factors in momentum space. In particular, the intra-orbital pairing of the {d_{{x^2} - {y^2}}} orbital has an s-wave like pairing form factor. The two methods also predict very different pairing strength on different parts of Fermi surfaces. These results suggest that BaCoSO and related materials can be a new ground to test and establish fundamental principles for unconventional high temperature superconductivity.

Misfit dislocations and phase transformations in high-T sub c superconducting films

CERN Document Server

Gutkin, M Y

2002-01-01

A theoretical model is suggested that describes the effects of misfit stresses on defect structures, phase content and critical transition temperature T sub c in high-T sub c superconducting films. The focus is placed on the exemplary case of YBaCuO films deposited onto LaSrAlO sub 4 substrates. It is theoretically revealed here that misfit stresses are capable of inducing phase transformations controlled by the generation of misfit dislocations in growing cuprate films. These transformations, in the framework of the suggested model, account for experimental data on the influence of the film thickness on phase content and critical temperature T sub c of superconducting cuprate films, reported in the literature. The potential role of stress-assisted phase transformations in suppression of critical current density across grain boundaries in high-T sub c superconductors is briefly discussed.

Hole superconductivity

International Nuclear Information System (INIS)

Hirsch, J.E.; Marsiglio, F.

1989-01-01

The authors review recent work on a mechanism proposed to explain high T c superconductivity in oxides as well as superconductivity of conventional materials. It is based on pairing of hole carriers through their direct Coulomb interaction, and gives rise to superconductivity because of the momentum dependence of the repulsive interaction in the solid state environment. In the regime of parameters appropriate for high T c oxides this mechanism leads to characteristic signatures that should be experimentally verifiable. In the regime of conventional superconductors most of these signatures become unobservable, but the characteristic dependence of T c on band filling survives. New features discussed her include the demonstration that superconductivity can result from repulsive interactions even if the gap function does not change sign and the inclusion of a self-energy correction to the hole propagator that reduces the range of band filling where T c is not zero

Correlation mediated superconductivity in a 'High-Tsub(c)' model

International Nuclear Information System (INIS)

Long, M.W.

1987-08-01

A simple model is presented to account for the High-Tsub(c) perovskite superconductors. The superconducting mechanism is purely electronic and comes from local Hubbard correlations. The model comprises a Hubbard model for the copper sites with a single particle oxygen band between the two copper Hubbard bands. The electrons move only between nearest neighbour atoms which are of different types. Using two very different approximation schemes, one related to 'Slave-Boson' mean field theory and the other based on an exact local Fermion transformation, the possibility of copper-oxygen or a mixture of copper-oxygen and oxygen-oxygen pairing is shown. The author believes that the most promising situation for superconductivity is with the Oxygen band over half-filled and closer in energy to the lower Hubbard band. (author)

Trapped magnetic field of a superconducting bulk magnet in high- T sub c RE-Ba-Cu-O

CERN Document Server

Fujimoto, H; Higuchi, T; Nakamura, Y; Kamijo, H; Nagashima, K; Murakami, M

1999-01-01

Superconducting magnets made of high-T sub c superconductors are promising for industrial applications. It is well known that REBa sub 2 Cu sub 3 O sub 7 sub - sub x and LRE (light rare-earth) Ba sub 2 Cu sub 3 O sub 7 sub - sub x superconductors prepared by melt processes have a high critical current density, J sub c , at 77 K and high magnetic fields. Therefore, the materials are very prospective for high magnetic field application as a superconducting permanent/bulk magnet with liquid-nitrogen refrigeration. LREBaCuO bulks, compared with REBaCuO bulks, exhibit a larger J sub c in high magnetic fields and a much improved irreversibility field, H sub i sub r sub r , at 77 K. In this study, we discuss the possibility and trapped field properties of a superconducting bulk magnet, as well as the melt processing for bulk superconductors and their characteristic superconducting properties. One of the applications is a superconducting magnet for the future magnetically levitated (Maglev) train.

d+s wave superconductivity: analysis of the electronic Raman data of YBa2Cu3O7-δ and other cuprates

International Nuclear Information System (INIS)

Nemetschek, R.; Hackl, R.; Opel, M.; Philipp, R.; Beal-Monod, M.T.; Bieri, J.B.; Maki, K.; Erb, A.; Walker, E.

1998-01-01

After briefly recalling the d+s model valid for some anisotropic high T c superconductors, we present a theory of electronic Raman spectra in that model and then compare it with new experimental data obtained for an overdoped Y123 single crystal. The d+s model appears to describe satisfactorily the experimental results, indicating a possible doping dependence of the mixing ratio. We note that the Raman spectrum of the overdoped Bi2212 could also be accounted for by the d+s superconductivity model. The case of Hg1212 (or Hg1223) is reexamined. It appears that the spontaneous breakdown of d-wave symmetry may be rather universal in high T c cuprates. (orig.)

Superconducting magnetic shields production. Realisation d'ecrans magnetiques supraconducteurs

Energy Technology Data Exchange (ETDEWEB)

Lainee, F; Kormann, R [Thomson-CSF, Domaine de Corbeville, 91 - Orsay (FR); Lainee, F [Ecole des Mines de Paris, 91 - Evry (FR)

1992-02-01

Low fields and low frequency shielding properties of YBCO magnetic shields are measured at 77 K. They compare favourably with shielding properties of mumetal shields. Therefore high-T{sub c} superconducting magnetic shields can already be used to shield small volumes. The case of magnetic shields for large volumes is also discussed. 3 refs; 6 figs; 4 tabs.

Superconducting homopolar motor and conductor development

Science.gov (United States)

Gubser, Donald U.

1996-10-01

The U.S. Navy has been developing superconducting homopolar motors for ship applications since 1969; a successful at-sea demonstration of the first motor, using NbTi wire for the magnet, was achieved in the early 1980s. Recently, this same motor was used as a test bed to demonstrate progress in high-critical-temperature superconducting magnet technology using bismuth-strontium- calcium-copper-oxide (BSCCO) compounds. In the fall of 1995, this motor achieved a performance of 124 kW operating at a temperature of 4.2 K and 91 kW while operating at 28 K. Future tests are scheduled using new magnets with conductors of both the 2223 and the 2212 BSCCO phases. This article describes the advantages of superconducting propulsion and recent progress in the development of BSCCO conductors for use in Navy power systems.

Possible universal cause of high-Tc superconductivity in different metals

International Nuclear Information System (INIS)

Amusia, M.Ya.; Shaginyan, V.R.

2002-01-01

Using the theory of the high temperature superconductivity based on the idea of the fermion condensation quantum phase transition (FCQPT) it is shown that neither the d-wave pairing symmetry, nor the pseudogap phenomenon, nor the presence of the Cu-O 2 planes are of decisive importance for the existence of the high-T c superconductivity. The analysis of recent experimental data on this type of superconductivity in different materials is carried out. It is shown that these facts can be understood within the theory of superconductivity based on the FCQPT. The main features of a room-temperature superconductor are discussed [ru

Superconduction at 77 K

International Nuclear Information System (INIS)

Mueller, H.G.

1989-01-01

This general paper deals with the advantages which may result from the use of ceramic high-temperature superconductors. The use of these new superconductors for generators and electric motors for ship propulsion is regarded as a promising potential defense application. Furthermore, SMES (Superconducting Magnetic Energy Storage) can be used as a 'power compressor' for future high-performance weapon systems such as electromagnetic cannons, high-energy lasers, and high power microwaves. (MM) [de

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.

Ship design methodologies of preliminary design

CERN Document Server

Papanikolaou, Apostolos

2014-01-01

This book deals with ship design and in particular with methodologies of the preliminary design of ships. The book is complemented by a basic bibliography and five appendices with useful updated charts for the selection of the main dimensions and other basic characteristics of different types of ships (Appendix A), the determination of hull form  from the data of systematic hull form series (Appendix B), the detailed description of the relational method for the preliminary estimation of ship weights (Appendix C), a brief review of the historical evolution of shipbuilding science and technology from the prehistoric era to date (Appendix D) and finally a historical review of regulatory developments of ship's damage stability to date (Appendix E).  The book can be used as textbook for ship design courses or as additional reading for university or college students of naval architecture courses and related disciplines; it may also serve as a reference book for naval architects, practicing engineers of rel...

Interface superconductivity

Energy Technology Data Exchange (ETDEWEB)

Gariglio, S., E-mail: stefano.gariglio@unige.ch [DQMP, Université de Genève, 24 Quai E.-Ansermet, CH-1211 Genève (Switzerland); Gabay, M. [Laboratoire de Physique des Solides, Bat 510, Université Paris-Sud 11, Centre d’Orsay, 91405 Orsay Cedex (France); Mannhart, J. [Max Planck Institute for Solid State Research, 70569 Stuttgart (Germany); Triscone, J.-M. [DQMP, Université de Genève, 24 Quai E.-Ansermet, CH-1211 Genève (Switzerland)

2015-07-15

Highlights: • We discuss interfacial superconductivity, a field boosted by the discovery of the superconducting interface between LaAlO. • This system allows the electric field control and the on/off switching of the superconducting state. • We compare superconductivity at the interface and in bulk doped SrTiO. • We discuss the role of the interfacially induced Rashba type spin–orbit. • We briefly discuss superconductivity in cuprates, in electrical double layer transistor field effect experiments. • Recent observations of a high T{sub c} in a monolayer of FeSe deposited on SrTiO{sub 3} are presented. - Abstract: Low dimensional superconducting systems have been the subject of numerous studies for many years. In this article, we focus our attention on interfacial superconductivity, a field that has been boosted by the discovery of superconductivity at the interface between the two band insulators LaAlO{sub 3} and SrTiO{sub 3}. We explore the properties of this amazing system that allows the electric field control and on/off switching of superconductivity. We discuss the similarities and differences between bulk doped SrTiO{sub 3} and the interface system and the possible role of the interfacially induced Rashba type spin–orbit. We also, more briefly, discuss interface superconductivity in cuprates, in electrical double layer transistor field effect experiments, and the recent observation of a high T{sub c} in a monolayer of FeSe deposited on SrTiO{sub 3}.

Asymmetric d-wave superconducting topological insulator in proximity with a magnetic order

Science.gov (United States)

Khezerlou, M.; Goudarzi, H.; Asgarifar, S.

2018-02-01

In the framework of the Dirac-Bogoliubov-de Gennes formalism, we investigate the transport properties in the surface of a 3-dimensional topological insulator-based hybrid structure, where the ferromagnetic and superconducting orders are simultaneously induced to the surface states via the proximity effect. The superconductor gap is taken to be spin-singlet d-wave symmetry. The asymmetric role of this gap respect to the electron-hole exchange, in one hand, affects the topological insulator superconducting binding excitations and, on the other hand, gives rise to forming distinct Majorana bound states at the ferromagnet/superconductor interface. We propose a topological insulator N/F/FS junction and proceed to clarify the role of d-wave asymmetry pairing in the resulting subgap and overgap tunneling conductance. The perpendicular component of magnetizations in F and FS regions can be at the parallel and antiparallel configurations leading to capture the experimentally important magnetoresistance (MR) of junction. It is found that the zero-bias conductance is strongly sensitive to the magnitude of magnetization in FS region mzfs and orbital rotated angle α of superconductor gap. The negative MR only occurs in zero orbital rotated angle. This result can pave the way to distinguish the unconventional superconducting state in the relating topological insulator hybrid structures.

Superconducting β-ZrNClx probed by scanning-tunnelling and break-junction spectroscopy

International Nuclear Information System (INIS)

Ekino, Toshikazu; Sugimoto, Akira; Gabovich, Alexander M.; Zheng, Zhanfeng; Yamanaka, Shoji

2013-01-01

Highlights: •STM/STS combined with break-junction tunnelling spectroscopy (BJTS) on β-ZrNCl. •STM image on the ab plane shows triangular atomic lattice spots with a period of 0.36 nm. •The gap peaks are widely distributed (Δ p–p = 9–28 meV)over the area of 100 nm 2 . •Average gap ratio 2Δ/k B T c ∼ 10 is confirmed by both STS and BJTS. -- Abstract: Superconducting layered compound β-ZrNCl x (x = 0.7) with the critical temperature T c = 13–14 K was investigated by means of scanning tunnelling microscopy/spectroscopy. The single-crystal domain facet of ∼100 μm 2 in the c-axis-oriented polycrystal was used as a probing surface. The STM image at 4.9 K shows triangular atomic lattice spots with the period of ∼0.36 nm, which agrees with the X-ray diffraction measurements. The STS measurements of the local conductance, dI/dV, exhibit broadened gap structures with a substantial distribution of the gap-edge values. Most frequently observed peak-to-peak value of ∼20 mV is remarkably similar to the superconducting gap edge of the isostructural β-HfNCl x with T c = 24 K. Temperature, T, dependence of the dI/dV shows that the gap structure disappears above T c ∼ 13 K. Fitting of the dI/dV curve by the broadened BCS density of states leads to the superconducting gap of 2Δ(4.9 K) = 11–13 meV. This is in accordance with our former break-junction data confirming the intrinsic character of the previously obtained extremely large gap to T c ratio 2Δ(0)/k B T c ≈ 10 (k B is the Boltzmann constant), thereby pointing to the unusual superconducting properties of this compound

The effect of hydrogen on the superconducting and structural properties of b.c.c. Nb-Ru alloys

International Nuclear Information System (INIS)

Robbins, C.G.; Ishikawa, M.; Treyvaud, A.; Muller, J.

1975-01-01

The superconducting transition temperature (Tsub(c)) has been measured before and after the introduction of hydrogen into Nbsub((1-x))Rusub(x) (0.20<=x<=0.33). In all cases, the presence of appreciable amounts of this interstitial component led to a sharp increase in the Tsub(c). All the evidence suggests that conversion of the host metal lattice to f.c.c. is necessary for the appearance of the elevated Tsub(c). (author)

Investigation of 3-D RCS Image formation of ships using ISAR

CSIR Research Space (South Africa)

Lord, RT

2006-05-01

Full Text Available Conventional Inverse Synthetic Aperture Radar (ISAR) utilises the rotational motion of a target such as a ship or an aircraft to obtain a 2-D image of the target’s radar cross section (RCS) profile from a coherent radar system. This concept can...

Superconducting coherence in a vortex line liquid

International Nuclear Information System (INIS)

Chen, T.; Teitel, S.

1995-01-01

We carry out simulations of the anisotropic uniformly frustrated 3d XY model, as a model for vortex line fluctuations in high T c superconductors. We compute the phase diagram as a function of temperature and anisotropy, for a fixed applied magnetic field B. We find two distinct phase transitions. Upon heating, there is first a lower T c perpendicular where the vortex line lattice melts and super-conducting coherence perpendicular to the applied magnetic field vanishes. At a higher T cz , within the vortex line liquid, superconducting coherence parallel to the applied magnetic field vanishes. For finite anisotropy, both T c perpendicular and T cz lie well below the crossover from the vortex line liquid to the normal state

High-T /SUB c/ Superconducting integrated circuit: a dc SQUID with input coil

International Nuclear Information System (INIS)

Di Iorio, M.S.; Beasley, M.R.

1985-01-01

We have fabricated a high transition temperature superconducting integrated circuit consisting of a dc SQUID and an input coupling coil. The purpose is to ascertain the generic problems associated with constructing a high-T /SUB c/ circuit as well as to fabricate a high performance dc SQUID. The superconductor used for both the SQUID and the input coil is Nb 3 Sn which must be deposited at 800 0 C. Importantly, the insulator separating SQUID and input coil maintains its integrity at this elevated temperature. A hole in the insulator permits contact to the innermost winding of the coil. This contact has been achieved without significant degradation of the superconductivity. Consequently, the device operates over a wide temperature range, from below 4.2 K to near T /SUB c/

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.)

Superconductivity in intercalated and substituted Y2Br2C2

International Nuclear Information System (INIS)

Baecker, M.; Simon, A.; Kremer, R.K.; Mattausch, H.J.; Dronskowski, R.; Rouxel, J.

1996-01-01

Layer compounds of the type Y 2 X 2 C 2 (X=Cl, Br, I) show superconductivity at temperatures between 2.3 and 11.2 K. The transition temperature is related to the tendency of conduction electrons toward pairwise localization in C 2 -π * states at the Fermi level, and changes with the concentration of valence electrons, which is varied by intercalation of Na. (orig.)

Superconductivity and transport properties in LaRu4Sb12 single crystals probed by radiation-induced disordering

International Nuclear Information System (INIS)

Goshchitskii, B.; Naumov, S.; Kostromitina, N.; Karkin, A.

2007-01-01

Resistivity ρ(T) and Hall coefficient R H (T) in magnetic fields H up to 14 T were studied in superconducting (T c = 3.3 K) LaRu 4 Sb 12 single crystals disordered by fast neutron irradiation. Atomic disordering leads to increase in residual resistivity ρ 0 , decrease of Hall number and suppression of superconductivity. The upper critical field slope -dH c2 /dT increases approximately linear with ρ 0 . The irradiation effects are almost recovered after annealing at 500 deg. C. The observed radiation-induced effects in LaRu 4 Sb 12 are compared with those in PrOs 4 Sb 12 in terms of unconventional mechanisms of superconductivity

Crystal structure of 200 K-superconducting phase in sulfur hydride system

Energy Technology Data Exchange (ETDEWEB)

Einaga, Mari; Sakata, Masafumi; Ishikawa, Takahiro; Shimizu, Katsuya [KYOKUGEN, Graduate School of Engineering Science, Osaka Univ. (Japan); Eremets, Mikhail; Drozdov, Alexander; Troyan, Ivan [Max Planck Institut fuer Chemie, Mainz (Germany); Hirao, Naohisa; Ohishi, Yasuo [JASRI/SPring-8, Hyogo (Japan)

2016-07-01

Superconductivity with the critical temperature T{sub c} above 200 K has been recently discovered by compression of H{sub 2}S (or D{sub 2}S) under extreme pressure. It was proposed that these materials decompose under high pressure to elemental sulfur and hydride with higher content of hydrogen which is responsible for the high temperature superconductivity. In this study, we have investigated that the crystal structure of the superconducting compressed H{sub 2}S and D{sub 2}S by synchrotron x-ray diffraction measurements combined with electrical resistance measurements at room and low temperatures. We found that the superconducting phase is in good agreement with theoretically predicted body-centered cubic structure, and coexists with elemental sulfur, which claims that the formation of 3H{sub 2}S → 2H{sub 3}S + S is occured under high pressure.

A high Tc superconducting liquid nitrogen level sensor

International Nuclear Information System (INIS)

Jin, J. X.; Liu, H. K.; Dou, S. X.; Grantham, C.; Beer, J.

1996-01-01

Full text: The dramatic resistance change in the superconducting-normal transition temperature range enables a high T c superconductor to be considered for designing a liquid nitrogen level sensor. A (Bi,Pb) 2 Sr 2 Ca 2 Cu 3 O 10+x Ag clad superconducting wire is selected and tested as a continuous liquid nitrogen level sensor to investigate the possibility for this application. The (Bi,Pb) 2 Sr 2 Ca 2 Cu 3 O 10+x Ag clad superconducting wire has approximately 110 K critical temperature, with more flexible and stable properties compared with bulk shape ceramic high T c superconductors. The voltage drops across the sensor are tested with different immersion lengths in liquid nitrogen. The accuracy of the HTS sensor is analysed with its dR/dT in the superconducting-normal transition range. The voltage signal is sensitive to liquid nitrogen level change, and this signal can be optimized by controlling the transport current. The problems of the Ag clad superconductor are that the Ag sheath thermal conductivity is very high, and the sensor normal resistance is low. These are the main disadvantages for using such a wire as a continuous level sensor. However, a satisfactory accuracy can be achieved by control of the transport current. A different configuration of the wire sensor is also designed to avoid this thermal influence

The circular form of the linear superconducting machine for marine propulsion

Science.gov (United States)

Rakels, J. H.; Mahtani, J. L.; Rhodes, R. G.

1981-01-01

The superconducting linear synchronous machine (LSM) is an efficient method of propulsion of advanced ground transport systems and can also be used in marine engineering for the propulsion of large commercial vessels, tankers, and military ships. It provides high torque at low shaft speeds and ease of reversibility; a circular LSM design is proposed as a drive motor. The equipment is compared with the superconducting homopolar motors, showing flexibility in design, built in redundancy features, and reliability.

Interplay of CDW, SDW and superconductivity in high-T{sub c} cuprates

Energy Technology Data Exchange (ETDEWEB)

Panda, S K [K.D. Science College, Pochilima, Hinjilicut 761 101, Ganjam, Orissa (India); Rout, G.C., E-mail: gcr@iopb.res.i [Condensed Matter Physics Group, Dept. of Applied Physics and Ballistics, F.M. University, Balasore 756 019, Orissa (India)

2009-07-01

We present a model calculation of the interplay of the charge density wave (CDW), spin density wave (SDW) and superconductivity in high temperature superconductors. In low doping situation the long range antiferromagnetic order is destroyed to give rise to SDW state accompanied by a CDW state in the system due to doping. For suitable doping the superconductivity appears in the system. The CDW state may describe the pseudogap phenomenon which co-exists with the superconducting phase and extends to normal phase in high-T{sub c} systems. These three competiting interactions co-exist together. These three gap parameters are calculated from the model Hamiltonian and solved self-consistently. By varying their coupling constants their interplay are investigated. Finally density of states is calculated for the conduction band which displays the experimental conductance data of Ekino et al. [T. Ekino, Y. Sezaki, H. Fujji, Phys. Rev. B 60 (1999) 6916].

Theory of High-T{sub c} Superconducting Cuprates Based on Experimental Evidence

Science.gov (United States)

Abrikosov, A. A.

1999-12-10

A model of superconductivity in layered high-temperature superconducting cuprates is proposed, based on the extended saddle point singularities in the electron spectrum, weak screening of the Coulomb interaction and phonon-mediated interaction between electrons plus a small short-range repulsion of Hund's, or spin-fluctuation, origin. This permits to explain the large values of T{sub c}, features of the isotope effect on oxygen and copper, the existence of two types of the order parameter, the peak in the inelastic neutron scattering, the positive curvature of the upper critical field, as function of temperature etc.

Superconducting technology

International Nuclear Information System (INIS)

2010-01-01

Superconductivity has a long history of about 100 years. Over the past 50 years, progress in superconducting materials has been mainly in metallic superconductors, such as Nb, Nb-Ti and Nb 3 Sn, resulting in the creation of various application fields based on the superconducting technologies. High-T c superconductors, the first of which was discovered in 1986, have been changing the future vision of superconducting technology through the development of new application fields such as power cables. On basis of these trends, future prospects of superconductor technology up to 2040 are discussed. In this article from the viewpoints of material development and the applications of superconducting wires and electronic devices. (author)

Development of 1 MW-class HTS motor for podded ship propulsion system

Energy Technology Data Exchange (ETDEWEB)

Umemoto, K; Aizawa, K; Yokoyama, M; Yoshikawa, K [Kawasaki Heavy Industries LTD., 673-8666, Hyogo (Japan); Kimura, Y; Izumi, M [Tokyo University of Marine Science Technology, 135-8533, Tokyo (Japan); Ohashi, K; Numano, M [National Maritime Research Institute, 181-0004, Tokyo (Japan); Okumura, K; Yamaguchi, M; Gocho, Y; Kosuge, E, E-mail: umemoto@ati.khi.co.j [Japan Super-conductivity Organization Co. LTD., 135-8533, Tokyo (Japan)

2010-06-01

To reduce fuel consumption and lead to a major reduction of pollution from NOx, SOx and CO{sub 2}, the electric ship propulsion system is one of the most prospective substitutes for conventional ship propulsion systems. In order to spread it, innovative technologies for the improvement of the power transmission are required. The high temperature superconducting technology has the possibility for a drastic reduction of power transmission loss. Recently, electric podded propulsions have become popular for large cruise vessels, icebreakers and chemical tankers because of the flexibility of the equipment arrangement and the stern hull design, and better maneuverability in harbour, etc. In this paper, a 1 MW-class High temperature superconducting (HTS) motor with high efficiency, smaller size and simple structure, which is designed and manufactured for podded propulsion, is reported. For the case of a coastal ship driven by the optimized podded propulsion in which the 1MW HTS motor is equipped, the reductions of fluid dynamic resistance and power transmission losses are demonstrated. The present research and development has been supported by the New Energy and Industrial Technology Development Organization (NEDO).

The interplay of magnetic order and superconductivity in GdxY1-xNi2B2C

International Nuclear Information System (INIS)

Drzazga, Z.; Fuchs, G.; Handstein, A.; Nenkov, K.; Mueller, K.-H.

2003-01-01

Resistivity, ac susceptibility and magnetization measurements are reported for polycrystalline samples of the Gd x Y 1-x Ni 2 B 2 C series as a function of temperature and magnetic field. The magnetic Gd impurities cause an almost linear decrease of the superconducting transition temperature T c with increasing Gd content in the range of x c have been observed. The effect of the 4f local moments manifests in a complete suppression of superconductivity for x≥0.3 and in antiferromagnetic ordering for x>0.3. In zero applied magnetic field, a distinct concentration region around x∼0.3 has been revealed separating superconductivity and antiferromagneting ordering. A metamagnetic transition has been observed in the compound with x=0.5 at a magnetic field of 0.8 T

Chiral d -wave superconductivity in a triangular surface lattice mediated by long-range interaction

Science.gov (United States)

Cao, Xiaodong; Ayral, Thomas; Zhong, Zhicheng; Parcollet, Olivier; Manske, Dirk; Hansmann, Philipp

2018-04-01

Adatom systems on the Si(111) surface have recently attracted an increasing attention as strongly correlated systems with a rich phase diagram. We study these materials by a single band model on the triangular lattice, including 1 /r long-range interaction. Employing the recently proposed TRILEX method, we find an unconventional superconducting phase of chiral d -wave symmetry in hole-doped systems. Contrary to usual scenarios where charge and spin fluctuations are seen to compete, here the superconductivity is driven simultaneously by both charge and spin fluctuations and crucially relies on the presence of the long-range tail of the interaction. We provide an analysis of the relevant collective bosonic modes and predict how a cumulative charge and spin paring mechanism leads to superconductivity in doped silicon adatom materials.

Clarification as to why alcoholic beverages have the ability to induce superconductivity in Fe1+dTe1−xSx

International Nuclear Information System (INIS)

Deguchi, K; Hara, H; Kawasaki, Y; Demura, S; Watanabe, T; Denholme, S J; Okazaki, H; Ozaki, T; Yamaguchi, T; Takeya, H; Takano, Y; Sato, D; Sugimoto, M; Soga, T; Tomita, M

2012-01-01

To elucidate the mechanism as to why alcoholic beverages can induce superconductivity in Fe 1+d Te 1−x S x samples, we performed component analysis and found that a weak acid such as an organic acid has the ability to induce superconductivity. Inductively coupled plasma spectroscopy was performed on weak acid solutions post-annealing. We found that the mechanism of inducement of superconductivity in Fe 1+d Te 1−x S x is the deintercalation of excess Fe from the interlayer sites. (paper)

Gauge Model of High-Tc Superconductivity

International Nuclear Information System (INIS)

Ng, Sze Kui

2012-01-01

A simple gauge model of superconductivity is presented. The seagull vertex term of this gauge model gives an attractive potential between electrons for the forming of Cooper pairs of superconductivity. This gauge model gives a unified description of superconductivity and magnetism including antiferromagnetism, pseudogap phenomenon, stripes phenomenon, paramagnetic Meissner effect, Type I and Type II supeconductivity and high-T c superconductivity. The doping mechanism of superconductivity is found. It is shown that the critical temperature T c is related to the ionization energies of elements and can be computed by a formula of T c . For the high-T c superconductors such as La 2-x Sr x CuO 4 , Y Ba 2 Cu 3 O 7 , and MgB 2 , the computational results of T c agree with the experimental results.

Charge ordering phenomena and superconductivity in underdoped cuprates

Energy Technology Data Exchange (ETDEWEB)

Tassini, Leonardo [Bayerische Akademie der Wissenschaften, Muenchen (Germany). Lehrstuhl E23 fuer Technische Physik

2008-01-16

In this thesis electronic properties of two prototypical copper-oxygen superconductors were studied with Raman scattering. The underdoped regime including the onset point of superconductivity p{sub sc1} was investigated. Evidence of quasi one-dimensional (1D) dynamical stripes was found. The 1D structures have a universal preferential orientation along the diagonals of the CuO{sub 2} planes below p{sub sc1}. At p{sub sc1}, lattice and electron dynamics change discontinuously. The results show that charge ordering drives the transition at p{sub sc1} and that the maximal transition temperature to superconductivity at optimal doping T{sub c}{sup MAX} depends on the type of ordering at p{sub sc1}. (orig.)

Trial Results of Ship Motions and Their Influence on Aircraft Operations for ISCS GUAM

Science.gov (United States)

1975-12-01

Washington, D.C. 20362 14, ;ZNITOAIv.O AGE[NCY NAME 6 X0AOORSS(RI iF1**1i; hedm cmtoUnd OilS caffe) iV Naval Ship Engineering Cmmand (Code 6136) Prince...component of the ship motions produced the difficulties. It was also regarded essencial to record the relative importance of ship motions as one of a

32 CFR 700.871 - Responsibility for safety of ships and craft at a naval station or shipyard.

Science.gov (United States)

2010-07-01

... a timely and adequate manner. (c) When a ship or craft not under her own power is being moved by... contractor. (d) When a ship operating under her own power is being drydocked, the commanding officer shall be... ship. (e) When a naval ship is to be drydocked in a private shipyard under a contract being...

Superconductivity in borides and carbides

International Nuclear Information System (INIS)

Muranaka, Takahiro

2007-01-01

It was thought that intermetallic superconductors do not exhibit superconductivity at temperatures over 30 K because of the Bardeen-Cooper-Schrieffer (BCS) limit; therefore, researchers have been interested in high-T c cuprates. Our group discovered high-T c superconductivity in MgB 2 at 39 K in 2001. This discovery has initiated a substantial interest in the potential of high-T c superconductivity in intermetallic compounds that include 'light' elements (borides, carbides, etc.). (author)

Superconductivity in CeCu/sub 2/Si/sub 2/: dependence of Tsub(c) on alloying and stoichiometry

Energy Technology Data Exchange (ETDEWEB)

Spille, H; Rauchschwalbe, U; Steglich, F [Technische Hochschule Darmstadt (Germany, F.R.). Inst. fuer Festkoerperphysik

1938-01-01

The authors have determined the transition temperatures of the alloy systems (Ce,M)Cu/sub 2/Si/sub 2/ with M = La, Y, Sc, Ce(Cu,T)/sub 2/Si/sub 2/ with T = Ag, Au, Mn, Ru, Rh, Pd and CeCu/sub 2/(Si,Ge)/sub 2/ as well as of CeCu/sub 2/Si/sub 2/ samples with varying stoichiometry. In each case, alloying is found to depress Tsub(c), the critical concentrations necessary to destroy superconductivity ranging between < 1 at.% and 10 at.%. Off-stoichiometry samples with a Cu- or Ce-deficiency of a few at.% are not superconducting, while samples prepared with a comparable excess of Cu or Ce show sharp transitions at Tsub(c) >approx. 600 mK. It is inferred that stoichiometric CeCu/sub 2/Si/sub 2/ contains substantial concentrations of Cu- and Ce-vacancies, which hinder superconductivity. First results on CeCu/sub 2/Si/sub 2/ single crystals, which exhibit bulk superconductivity, are also reported.

Real-Time Simulation of Ship-Structure and Ship-Ship Interaction

DEFF Research Database (Denmark)

Lindberg, Ole; Glimberg, Stefan Lemvig; Bingham, Harry B.

2013-01-01

, because it is simple, easy to implement and computationally efficient. Multiple many-core graphical processing units (GPUs) are used for parallel execution and the model is implemented using a combination of C/C++, CUDA and MPI. Two ship hydrodynamic cases are presented: Kriso Container Carrier at steady...

Superconductivity in graphite intercalation compounds

International Nuclear Information System (INIS)

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

2015-01-01

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 6 and YbC 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

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.

Interplay of structural transition and superconductivity in cuprates

International Nuclear Information System (INIS)

Ghosh, Haranath; Mitra, Manidipa; Behera, S.N.; Ghatak, S.K.

1997-01-01

The presence of lattice distortion is known to suppress the superconducting (SC) transition in the cuprates. It is now accepted that electron correlation plays a dominant role in shaping the properties of these undoped and doped systems. Furthermore, since the Fermi level in these systems lies in a degenerate band of Cu : d and O : p orbitals the structural transition can be modeled as a band Jahn-Teller effect. We study the coexistence of superconductivity and band Jahn-Teller (J-T) distortion, taking into account the electron correlation within the slave boson formalism. It is shown that with increasing dopant concentration (δ), the structural transition temperature (T s ) remains constant up to a certain value and then vanishes, while the SC transition temperature (T c ) increases to a maximum value. The highest value of T c corresponds to that value of δ where T s vanishes. Besides with increasing lattice distortion superconductivity is suppressed. These findings are in qualitative agreement with the experimental results. (author)

2nd Rochester Conference on Superconductivity in D- and F- Band Metals

CERN Document Server

Superconductivity in d- and f- band metals

1976-01-01

The occurrence of superconductivity among the d- and f-band metals remains one of the unsolved problems of physics. The first Rochester conference on this subject in October 1971 brought together approximately 100 experimentalists and theorists, and that conference was considered successful; the published proceedings well-represented the current research at that time and has served as a "handbook" to many. In the four and one half years since the first conference, impressive progress has been made in many areas (although Berndt Matthias would be one of the first to point out that raising the m"aximum transition temperature by a significant amount was not one of them). For a variety of reasons, I decided that it was time for a Second Rochester Conference on Superconductivity in d- and f-Band Metals and it was held on April 30 and May 1, 1976. It would appear that this conference was even more successful judging from the quality of the talks and various comments made to me. I believe that this was due...

3D multiphysics modeling of superconducting cavities with a massively parallel simulation suite

Directory of Open Access Journals (Sweden)

Oleksiy Kononenko

2017-10-01

Full Text Available Radiofrequency cavities based on superconducting technology are widely used in particle accelerators for various applications. The cavities usually have high quality factors and hence narrow bandwidths, so the field stability is sensitive to detuning from the Lorentz force and external loads, including vibrations and helium pressure variations. If not properly controlled, the detuning can result in a serious performance degradation of a superconducting accelerator, so an understanding of the underlying detuning mechanisms can be very helpful. Recent advances in the simulation suite ace3p have enabled realistic multiphysics characterization of such complex accelerator systems on supercomputers. In this paper, we present the new capabilities in ace3p for large-scale 3D multiphysics modeling of superconducting cavities, in particular, a parallel eigensolver for determining mechanical resonances, a parallel harmonic response solver to calculate the response of a cavity to external vibrations, and a numerical procedure to decompose mechanical loads, such as from the Lorentz force or piezoactuators, into the corresponding mechanical modes. These capabilities have been used to do an extensive rf-mechanical analysis of dressed TESLA-type superconducting cavities. The simulation results and their implications for the operational stability of the Linac Coherent Light Source-II are discussed.

Radiation effects on superconductivity

International Nuclear Information System (INIS)

Brown, B.S.

1975-01-01

The effect of radiation on the superconducting transition temperature (T/sub c/), upper critical field (H/sub c2/), and volume-pinning-force density (F/sub p/) were discussed for the three kinds of superconducting material (elements, alloys, and compounds). 11 figures, 3 tables, 86 references

The influence of impurity concentration and magnetic fields on the superconducting transition of high-purity titanium

Energy Technology Data Exchange (ETDEWEB)

Peruzzi, A.; Gottardi, E.; Peroni, I.; Ponti, G.; Ventura, G

1999-08-01

The influence of impurity concentration c and applied magnetic field H on the superconducting transition of high-purity commercial titanium samples was investigated. The superconductive transition temperature T{sub C} was found to be very sensitive to the impurity concentration (dT{sub C}/dc {approx} -0.6 mK/w.ppm) and to the applied magnetic field (dT{sub C}/dH {approx} -1.1 mK/G). A linear dependence of T{sub C} decrease on impurity concentration, as theoretically predicted by various authors, was observed. In the purest sample, a linear decrease of T{sub C} on the applied magnetic field was found. The run-to-run and sample-to-sample reproducibility of the transition of the same sample was evaluated, and its suitability as a thermometric reference point below 1 K was discussed.

Electronic properties of γ-U and superconductivity of U–Mo alloys

International Nuclear Information System (INIS)

Tkach, I.; Kim-Ngan, N.-T.H.; Warren, A.; Scott, T.; Gonçalves, A.P.; Havela, L.

2014-01-01

Highlights: • The bcc phase of uranium was stabilized to low temperature in U–Mo alloys. • Ultrafast cooling was utilized. • Negative coefficient dρ/dT indicates very strong disorder. • The alloys are superconducting with T c ≈ 2.1 K. • They exhibit high critical field exceeding 5 T. - Abstract: Fundamental electronic properties of γ-Uranium were determined using Mo doping combined with ultrafast (splat) cooling, which allowed stabilization of the bcc structure to low temperatures. The Sommerfeld coefficient γ e is enhanced to 16 mJ/mol K 2 from 11 mJ/mol K 2 for α-U. Magnetic susceptibility remains weak and T-independent, ≈5 × 10 −8 m 3 /mol. The Mo-doped γ-U exhibits a conventional BCS superconductivity with T c ≈ 2.1 K and critical field exceeding 5 T for 15 at.% Mo. This type of superconductivity is qualitatively different from the one found for pure U splat, which has T c higher than 1 K but the weak specific heat anomaly proves that it is not real bulk effect

The effect of pressure on the charge-density wave and superconductivity in ZrTe sub 3

CERN Document Server

Yamaya, K; Yasuzuka, S; Okajima, Y; Tanda, S

2002-01-01

The charge-density-wave (CDW) transition temperature, T sub C sub D sub W , of ZrTe sub 3 is found to increase for pressures up to 0.6 GPa, while the superconducting transition temperature, T sub c , decreases with increasing pressure. According to a band calculation, it is found that the pressure-induced enhancement of the CDW and suppression of the superconductivity are not simply explained by the effect of nesting of the Fermi surface, suggesting the possibility of a new relation for the competition between the CDW and superconductivity.

Imaging orbitals and defects in superconducting FeSe/SrTiO{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Hoffman, Jennifer [Harvard University, Cambridge, MA (United States); University of British Columbia, Vancouver (Canada); Huang, Dennis; Webb, Tatiana; Feng, Shiang; Kaxiras, Efthimios [Harvard University, Cambridge, MA (United States); Song, Can-Li [Harvard University, Cambridge, MA (United States); Tsinghua University, Beijing (China); Chang, Cui-Zu; Moodera, Jagadeesh [Massachusetts Institute of Technology, Cambridge, MA (United States)

2016-07-01

Single-layer FeSe grown epitaxially on SrTiO{sub 3} has been shown to superconduct with T{sub c} as high as 100 K, more than a factor of 10 higher than bulk FeSe. This dramatic enhancement motivates intense efforts to understand the superconducting mechanism and to design and fabricate devices. Nematic order, breaking the 4-fold rotational symmetry of the crystal, has been proposed as an important factor in the superconducting phase diagram. Meanwhile, atomic defects, which may pin nematic fluctuations or otherwise perturb superconductivity, can provide important clues into the superconducting mechanism as well as practical routes to superconducting devices. Here we use scanning tunneling microscopy (STM) to search for orbital nematicity in single-layer FeSe/SrTiO{sub 3}, and to investigate atomic-scale defects which locally influence superconductivity. From quasiparticle interference (QPI) images, we disentangle scattering intensities from the orthogonal Fe 3d{sub xz} and 3d{sub yz} bands, and quantitatively exclude pinned nematic orbital order with domain size larger than δ r ∝ 20 nm. Furthermore, we identify a prevalent ''dumbbell''-shaped atomic-scale defect whose placement could be harnessed to define two-dimensional superconducting devices.

Theory of high-T{sub C} superconductivity: transition temperature

Energy Technology Data Exchange (ETDEWEB)

Harshman, Dale R [Physikon Research Corporation, Lynden, WA 98264 (United States); Fiory, Anthony T [Department of Physics, New Jersey Institute of Technology, Newark, NJ 07102 (United States); Dow, John D, E-mail: drh@physikon.net [Department of Physics, Arizona State University, Tempe, AZ 85287 (United States)

2011-07-27

It is demonstrated that the transition temperature (T{sub C}) of high-T{sub C} superconductors is determined by their layered crystal structure, bond lengths, valency properties of the ions, and Coulomb coupling between electronic bands in adjacent, spatially separated layers. Analysis of 31 high-T{sub C} materials (cuprates, ruthenates, ruthenocuprates, iron pnictides, organics) yields the universal relationship for optimal compounds, k{sub B}T{sub C0} ={beta}/{iota}{zeta}, where {iota} is related to the mean spacing between interacting charges in the layers, {zeta} is the distance between interacting electronic layers, {beta} is a universal constant and T{sub C0} is the optimal transition temperature (determined to within an uncertainty of {+-} 1.4 K by this relationship). Non-optimum compounds, in which sample degradation is evident, e.g. by broadened superconducting transitions and diminished Meissner fractions, typically exhibit reduced T{sub C} < T{sub C0}. It is shown that T{sub C0} may be obtained from an average of the Coulomb interaction forces between the two layers.

Reactors. Nuclear propulsion ships

International Nuclear Information System (INIS)

Fribourg, Ch.

2001-01-01

This article has for object the development of nuclear-powered ships and the conception of the nuclear-powered ship. The technology of the naval propulsion P.W.R. type reactor is described in the article B.N.3 141 'Nuclear Boilers ships'. (N.C.)

Magnetism and superconductivity in Eu(Ho)Mo6S8

International Nuclear Information System (INIS)

Capone, D.W. II; Lai Fook, M.S.; Guertin, R.P.; Hinks, D.G.; Dunlap, B.D.; Foner, S.; Abou-Aly, A.I.; Brooks, J.S.

1984-10-01

A variety of ambient and high pressure experimental results reveal the interplay between magnetism and superconductivity in Ho doped samples of the pressure induced superconductor, EuMo 6 S 8 . Ho concentrations up to 50 atomic percent of the rare earth ions were used. High resolution magnetic measurements are consistent with the crystalline electric field ground state for the Ho 3+ ions being a magnetic doublet consisting largely of J/sub z/ = 18. The results of high pressure magnetization experiments reveal negligible effects of reduced lattice constant on the rare earth-rare earth interactions. Resistivity in a 10 atomic percent sample for P = 10 kbar shows the suppression of a P = 0 structural transition, metallic conductivity down to low temperatures, and finally superconductivity at 8 K. The upper critical field, H/sub c2/(T), for this sample was measured for P = 7, 10 and 12 kbar and showed strong reentrant behavior (dH/sub c2/(T)/dT > 0 as T → 0 K). A minimum with field in the resistivity above H/sub c2/ was also observed at lowest temperatures. The H/sub c2/(T) data are compared with those of EuMo 6 S 8 at high pressure, which shows positive curvature, and HoMo 6 S 8 , in which superconductivity is quenched by ferromagnetism at low temperatures. 14 references, 4 figures

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.

RIA Superconducting Drift Tube Linac R and D

International Nuclear Information System (INIS)

Popielarski, J.; Bierwagen, J.; Bricker, S.; Compton, C.; DeLauter, J.; Glennon, P.; Grimm, T.; Hartung, W.; Harvell, D.; Hodek, M.; Johnson, M.; Marti, F.; Miller, P.; Moblo, A.; Norton, D.; Popielarski, L.; Wlodarczak, J.; York, R.C.; Zeller, A.

2009-01-01

Cavity and cryomodule development work for a superconducting ion linac has been underway for several years at the National Superconducting Cyclotron Laboratory. The original application of the work was the proposed Rare Isotope Accelerator. At present, the work is being continued for use with the Facility for Rare Isotope Beams (FRIB). The baseline linac for FRIB requires 4 types of superconducting cavities to cover the velocity range needed to accelerate an ion beam to (ge) 200 MeV/u: 2 types of quarter-wave resonator (QWR) and 2 types of half-wave resonator (HWR). Superconducting solenoids are used for focusing. Active and passive shielding is required to ensure that the solenoids field does not degrade the cavity performance. First prototypes of both QWR types and one HWR type have been fabricated and tested. A prototype solenoid has been procured and tested. A test cryomodule has been fabricated and tested. The test cryomodule contains one QWR, one HWR, one solenoid, and one super-ferric quadrupole. This report covers the design, fabrication, and testing of this cryomodule

Crossover from BCS to composite boson (local pair) superconductivity in quasi-2D systems

International Nuclear Information System (INIS)

Gorbar, E.V.; Loktev, V.M.; Sharapov, S.G.

1995-01-01

The crossover from cooperative Cooper pairing to independent bound state (composite bosons) formation and condensation in quasi-2 D systems is studied. It is shown that at low carrier density the critical superconducting temperature is equal to the temperature of Bose-condensation of ideal quasi-2 D Bose-gas with heavy dynamical mass, meanwhile at high densities the BCS result remains valid. 15 refs

Reversal of the Upper Critical Field Anisotropy and Spin-Locked Superconductivity in K2Cr3As3

International Nuclear Information System (INIS)

Balakirev, Fedor Fedorovich; Kong, T.; Jaime, Marcelo; McDonald, Ross David; Mielke, Charles H.; Gurevich, A.; Canfield, P. C.; Bud'ko, S. L.

2016-01-01

Recently, superconductivity in K 2 Cr 3 As 3 (T c =6.1 K) was discovered. The crystalline lattice contains an array of weakly coupled, double well [(Cr 3 As 3 ) 2- ] ∞ linkages stretched along the c axis, suggesting the possibility of quasi-one-dimensional superconductivity. Moderately anisotropic upper critical field was revealed in single crystals, with very large initial slopes, dH || c2 /dT=12 T/K along the Cr chains and dH perpendicular c2 /dT =7 T/K perpendicular to the chains. Given the ambiguity of conclusions based on the extrapolations of H c2 (T) measured near T c to low temperatures, we performed high-field measurements of H c2 (T) on K 2 Cr 3 As 3 single crystals in pulsed magnetic fields which enabled us to reveal the full anisotropic H c2 (T) curves from T c down to 600 mK.

Phase separation and d-wave superconductivity induced by extended electron-exciton interaction

Energy Technology Data Exchange (ETDEWEB)

Cheng Ming [Department of Physics and Texas Center for Superconductivity, University of Houston, 4800 Calhoun Road, Houston, Texas 77204 (United States)], E-mail: cheng896@hotmail.com; Su Wupei [Department of Physics and Texas Center for Superconductivity, University of Houston, 4800 Calhoun Road, Houston, Texas 77204 (United States)

2008-12-15

Using an auxiliary-field quantum Monte Carlo (AFQMC) method, we have studied a two-dimensional tight-binding model in which the conduction electrons can polarize an adjacent layer of molecules through electron-electron repulsion. Calculated average conduction electron density as a function of chemical potential exhibits a clear break characteristic of phase separation. Compared to the noninteracting system, the d-wave pair-field correlation function shows significant enhancement. The simultaneous presence of phase separation and d-wave superconductivity suggests that an effective extended pairing force is induced by the electron-exciton coupling.

Phase separation and d-wave superconductivity induced by extended electron-exciton interaction

International Nuclear Information System (INIS)

Cheng Ming; Su Wupei

2008-01-01

Using an auxiliary-field quantum Monte Carlo (AFQMC) method, we have studied a two-dimensional tight-binding model in which the conduction electrons can polarize an adjacent layer of molecules through electron-electron repulsion. Calculated average conduction electron density as a function of chemical potential exhibits a clear break characteristic of phase separation. Compared to the noninteracting system, the d-wave pair-field correlation function shows significant enhancement. The simultaneous presence of phase separation and d-wave superconductivity suggests that an effective extended pairing force is induced by the electron-exciton coupling

3D analytical method for the external dynamics of ship collisions and investigation of the coefficient of restitution

Directory of Open Access Journals (Sweden)

LIU Junfeng

2017-03-01

Full Text Available The analytical method for predicting the dynamic responses of a ship in a collision scenario features speed and accuracy,and the external dynamics constitute an important part. A 3D simplified analytical method is implemented by MATLAB and used to calculate the energy dissipation of ship-ship collisions. The results obtained by the proposed method are then compared with those of a 2D simplified analytical method. The total dissipated energy can be obtained through the proposed analytical method, and the influence of the collision heights,angles and locations on the dissipated energy is discussed on that basis. Furthermore,the effects of restitution on the conservative coefficients and the effects of conservative coefficients on energy dissipation are discussed. It is concluded that the proposed 3D analysis yields a lesser energy dissipation than that of the 2D analysis,and the collision height has a significant influence on the dissipated energy. In using the proposed simplified method,it is not safe to simplify the conservative coefficient as zero when the collision angle is greater than 90 degrees. In the future research, to get more accurate energy dissipation, it is a good way to adopt the 3D simplified analytical method instead of the 2D method.

SHIP2 associates with intersectin and recruits it to the plasma membrane in response to EGF.

Science.gov (United States)

Xie, Jingwei; Vandenbroere, Isabelle; Pirson, Isabelle

2008-09-03

We identified intersectin1 (ITSN1) as a new binding partner of the SH2 domain containing inositol 5-phosphatase 2 (SHIP2). The interaction between SHIP2 and ITSN1 was confirmed in vivo. Src homology 3D, A, C, and E domains of ITSN1 were shown to be implicated in the interaction. In response to epidermal growth factor, SHIP2 expression could recruit the ITSN1 short form (ITSN1-S) to the cell membrane, while SHIP2 overexpression did not modulate the ITSN-mediated extracellular signal-regulated kinase1/2 and c-Jun NH2-terminal kinase activation. Our data provide a molecular link between SHIP2 and ITSN1 which are involved in receptor endocytosis regulation.

Destruction of superconductivity in the Bi2Sr2Ca1-xGdxCu2-yLiyO8+d system

International Nuclear Information System (INIS)

Jayaram, B.; Lanchester, P.C.; Weller, M.T.

1991-01-01

We have measured the T c , resistivity, and magnetoresistivity of a series of Bi 2 Sr 2 Ca 1-x Gd x Cu 2-y Li y O 8+d samples, with x=0 and 0.4 and 0≤y≤0.6. We find that the suppression of T c , the logarithmic variation of the resistivity above the superconducting transition, and the field-independent nature of the temperature variation of magnetoresistivity illustrate the enhancement of the Coulomb interaction with increasing normal-state resistivity (ρ n ). We also find a gradual crossover from a logarithmic to an exponential dependence with increasing ρ n

Spectral dimensionality of random superconducting networks

International Nuclear Information System (INIS)

Day, A.R.; Xia, W.; Thorpe, M.F.

1988-01-01

We compute the spectral dimensionality d of random superconducting-normal networks by directly examining the low-frequency density of states at the percolation threshold. We find that d = 4.1 +- 0.2 and 5.8 +- 0.3 in two and three dimensions, respectively, which confirms the scaling relation d = 2d/(2-s/ν), where s is the superconducting exponent and ν the correlation-length exponent for percolation. We also consider the one-dimensional problem where scaling arguments predict, and our numerical simulations confirm, that d = 0. A simple argument provides an expression for the density of states of the localized high-frequency modes in this special case. We comment on the connection between our calculations and the ''termite'' problem of a random walker on a random superconducting-normal network and point out difficulties in inferring d from simulations of the termite problem

Surveying, Modeling and 3d Representation of a wreck for Diving Purposes: Cargo Ship "vera"

Science.gov (United States)

Ktistis, A.; Tokmakidis, P.; Papadimitriou, K.

2017-02-01

This paper presents the results from an underwater recording of the stern part of a contemporary cargo-ship wreck. The aim of this survey was to create 3D representations of this wreck mainly for recreational diving purposes. The key points of this paper are: a) the implementation of the underwater recording at a diving site; b) the reconstruction of a 3d model from data that have been captured by recreational divers; and c) the development of a set of products to be used by the general public for the ex situ presentation or for the in situ navigation. The idea behind this project is to define a simple and low cost procedure for the surveying, modeling and 3D representation of a diving site. The perspective of our team is to repeat the proposed methodology for the documentation and the promotion of other diving sites with cultural features, as well as to train recreational divers in underwater surveying procedures towards public awareness and community engagement in the maritime heritage.

Impurity effects in superconducting UPt3

International Nuclear Information System (INIS)

Aronson, M.C.; Vorenkamp, T.; Koziol, Z.; de Visser, A.; Bakker, K.; Franse, J.J.M.; Smith, J.L.

1991-01-01

Superconducting UPt 3 is characterized by a novel and complex magnetic field-temperature phase diagram, with two superconducting transitions at T c1 and T c2 in zero field. We have studied the effects of Pd and Y impurities on the zero field superconducting properties of UPt 3 . Resistance measurements show that both dopants increase the residual resistivity and decrease the spin fluctuation temperature in the normal state. T c1 is depressed by both dopants, but more effectively by Pd. |T c1 - T c2 | is essentially unaffected by Y doping, but increases dramatically with Pd doping

Superconductivity in heavily boron-doped silicon carbide

Directory of Open Access Journals (Sweden)

Markus Kriener, Takahiro Muranaka, Junya Kato, Zhi-An Ren, Jun Akimitsu and Yoshiteru Maeno

2008-01-01

Full Text Available The discoveries of superconductivity in heavily boron-doped diamond in 2004 and silicon in 2006 have renewed the interest in the superconducting state of semiconductors. Charge-carrier doping of wide-gap semiconductors leads to a metallic phase from which upon further doping superconductivity can emerge. Recently, we discovered superconductivity in a closely related system: heavily boron-doped silicon carbide. The sample used for that study consisted of cubic and hexagonal SiC phase fractions and hence this led to the question which of them participated in the superconductivity. Here we studied a hexagonal SiC sample, free from cubic SiC phase by means of x-ray diffraction, resistivity, and ac susceptibility.

Development of Nb-Ti multifilamentar superconducting wires

International Nuclear Information System (INIS)

Otubo, J.

1986-01-01

Ni-Ti superconducting wires with multifilamentar configuration were produced, using the grouping technique. Some basic concepts on superconductivity and its main critical parameters are presented. The criteria for stabilizing superconductors in terms of the geometry are studied. The main critical parameters, H c , J c , T c in function of the composition and the metallurgical structure of Ni-Ti alloy are analysed. The development of Ni-Ti superconducting wires is described. (M.C.K.) [pt

The I{sub c}(H)-T{sub c}(H) phase boundary of superconducting Nb thin films with periodic and quasiperiodic antidot arrays

Energy Technology Data Exchange (ETDEWEB)

Bothner, D.; Kemmler, M.; Cozma, R.; Kleiner, R.; Koelle, D. [Physikalisches Institut and Center for Collective Quantum Phenomena, Universitaet Tuebingen (Germany); Misko, V.; Peeters, F. [Departement Fysica, Universiteit Antwerpen (Belgium); Nori, F. [Advanced Science Institute, RIKEN (Japan)

2011-07-01

The magnetic field dependent critical current I{sub c}(H) of superconducting thin films with artificial defects strongly depends on the symmetry of the defect arrangement. Likewise the critical temperature T{sub c}(H) of superconducting wire networks is heavily influenced by the symmetry of the system. Here we present experimental data on the I{sub c}(H)-T{sub c}(H) phase boundary of Nb thin films with artificial defect lattices of different symmetries. For this purpose we fabricated 60 nm thick Nb films with antidots in periodic (triangular) and five different quasiperiodic arrangements. The parameters of the antidot arrays were varied to investigate the influence of antidot diameter and array density. Experiments were performed with high temperature stability ({delta}T<1 mK) at 0.5{<=}T/T{sub c}{<=}1. From the I-V-characteristics at variable H and T we extract I{sub c}(H) and T{sub c}(H) for different voltage and resistance criteria. The experimental data for the critical current density are compared with results from numerical molecular dynamics simulations.

Superconducting quantum electronics

International Nuclear Information System (INIS)

Kose, V.

1989-01-01

This book reviews recent accomplishments, presents new results and discusses possible future developments of superconducting quantum electronics and high T c superconductivity. The three main parts of the book deal with fundamentals, sensitive detectors, and precision metrology. New results reported include: correct equivalent circuits modelling superconducting electronic devices; exact solution of the Mattis-Bardeen equations describing various experiments for thin films; complete theoretical description and experimental results for a new broad band spectrum analyzer; a new Josephson junction potentiometer allowing tracing of unknown voltage ratios back to well-known frequency ratios; and fast superconducting SQUID shift registers enabling the production of calculable noise power spectra in the microwave region

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...

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...

Stabilized superconducting materials and fabrication process

International Nuclear Information System (INIS)

Chevallier, B.; Dance, J.M.; Etourneau, J.; Lozano, L.; Tressaud, A.; Tournier, R.; Sulpice, A.; Chaussy, J.; Lejay, P.

1989-01-01

Superconducting ceramics are fluorinated at a temperature ≤ 120 0 C. Are also claimed new superconducting materials with a fluorine concentration gradient decreasing from the surface to the core. Superconductivity is stabilized and/or improved [fr

Atomic physics and quantum optics using superconducting circuits: from the Dynamical Casimir effect to Majorana fermions

Science.gov (United States)

Nori, Franco

2012-02-01

This talk will present an overview of some of our recent results on atomic physics and quantum optics using superconducting circuits. Particular emphasis will be given to photons interacting with qubits, interferometry, the Dynamical Casimir effect, and also studying Majorana fermions using superconducting circuits.[4pt] References available online at our web site:[0pt] J.Q. You, Z.D. Wang, W. Zhang, F. Nori, Manipulating and probing Majorana fermions using superconducting circuits, (2011). Arxiv. J.R. Johansson, G. Johansson, C.M. Wilson, F. Nori, Dynamical Casimir effect in a superconducting coplanar waveguide, Phys. Rev. Lett. 103, 147003 (2009). [0pt] J.R. Johansson, G. Johansson, C.M. Wilson, F. Nori, Dynamical Casimir effect in superconducting microwave circuits, Phys. Rev. A 82, 052509 (2010). [0pt] C.M. Wilson, G. Johansson, A. Pourkabirian, J.R. Johansson, T. Duty, F. Nori, P. Delsing, Observation of the Dynamical Casimir Effect in a superconducting circuit. Nature, in press (Nov. 2011). P.D. Nation, J.R. Johansson, M.P. Blencowe, F. Nori, Stimulating uncertainty: Amplifying the quantum vacuum with superconducting circuits, Rev. Mod. Phys., in press (2011). [0pt] J.Q. You, F. Nori, Atomic physics and quantum optics using superconducting circuits, Nature 474, 589 (2011). [0pt] S.N. Shevchenko, S. Ashhab, F. Nori, Landau-Zener-Stuckelberg interferometry, Phys. Reports 492, 1 (2010). [0pt] I. Buluta, S. Ashhab, F. Nori. Natural and artificial atoms for quantum computation, Reports on Progress in Physics 74, 104401 (2011). [0pt] I.Buluta, F. Nori, Quantum Simulators, Science 326, 108 (2009). [0pt] L.F. Wei, K. Maruyama, X.B. Wang, J.Q. You, F. Nori, Testing quantum contextuality with macroscopic superconducting circuits, Phys. Rev. B 81, 174513 (2010). [0pt] J.Q. You, X.-F. Shi, X. Hu, F. Nori, Quantum emulation of a spin system with topologically protected ground states using superconducting quantum circuit, Phys. Rev. A 81, 063823 (2010).

Evidence for superconducting effects on the measured resistivity well above T/sub c/ for a type-I bulk metal

International Nuclear Information System (INIS)

Sinvani, M.; Levy, B.; Greenfield, A.J.

1979-01-01

A superconducting contribution deltasigma (T) to the electrical conductivity sigma (T) has been observed at temperatures up to about twice the transition temperature T/sub c/ approx. = 1.17 K for bulk aluminum. The form of deltasigma (T) is found to be α[T/sub c//(T-T/sub c/)]/sup n/, with α independent of sigma (T), in agreement with the theory of superconducting fluctuations. However, significant differences from the theory are found, with α more than two orders of magnitude too large and n approx. = 3/4 rather than 1/2

2005 annual report of MEXT specially promoted research, 'Development of the 4D Space Access Neutron Spectrometer (4SEASONS) and elucidation of the Mechanism of Oxide High-Tc superconductivity'

International Nuclear Information System (INIS)

Arai, Masatoshi; Kajimoto, Ryoichi; Nakajima, Kenji; Shamoto, Shin'ichi; Soyama, Kazuhiko; Nakamura, Mitsutaka; Aizawa, Kazuya; Asaoka, Hidehito; Kodama, Katsuaki; Inamura, Yasuhiro; Imai, Yoshinori; Yokoo, Tetsuya; Ino, Takashi; Yamada, Kazuyoshi; Fujita, Masaki; Ohoyama, Kenji; Hiraka, Haruhiro

2006-11-01

A research project entitled 'Development of the 4D Space Access Neutron Spectrometer (4SEASONS) and Elucidation of the Mechanism of Oxide High-T c Superconductivity' has started in 2005 (repr. by M. Arai). It is supported by MEXT, Grant-in-Aid for Specially Promoted Research and is going to last until fiscal 2009. The goal of the project is to elucidate the mechanism of oxide high-T c superconductivity by neutron scattering technique. For this purpose, we will develop an inelastic neutron scattering instrument 4SEASONS (4d SpacE AccesS neutrON Spectrometer) for the spallation neutron source in Japan Proton Accelerator Research Complex (J-PARC). The instrument will have 100 times higher performance than existing world-class instruments, and will enable detailed observation of anomalous magnetic excitations and phonons in a four-dimensional momentum-energy space. This report summarizes the progress in the research project in fiscal 2005. (author)

Metallurgy, fabrication, and superconducting properties of multifilamentary Nb3Al composites

International Nuclear Information System (INIS)

Hafstrom, J.W.

1976-01-01

The control of metallurgical structure during fabrication that will improve the superconducting properties of multifilamentary, aluminium-stabilized, Nb 3 Al composites is described. Composites are fabricated by placing niobium rods in an aluminum matrix, and then drawing to wire. Nb 3 Al is formed at temperatures exceeding 1800 0 C for about 5 s and ordered at 750 0 C for 48 h. A critical current, J/sub c/(H), in excess of 10 5 A/cm 2 (F/sub p/ approximately equal to 7 x 10 8 dynes/cm 3 ) at 7 T and a T/sub c/ to 18.2 K are obtained. Attempts to improve J/sub c/(H) by controlling the grain size in the Nb 3 Al diffused layer are discussed. Precipitates, arising from the addition of carbon during Nb 3 Al layer growth, do not appear to be effective as grain-boundary or flux pinners. When 1 percent Zr is added to the Nb, the growth of the Nb 3 Al layer is accelerated, T/sub c/ is lowered and J/sub c/(H) is not significantly improved. J/sub c/(H) rapidly decreases with an increase in Nb 3 Al or (Nb-Zr) 3 Al layer thickness, d. J/sub c/(H) is independent of d in composites with d greater than or approximately equal to 1.5 μm. In general, the Nb 3 Al grain size appears comparable to d for d less than or equal to 1 μm. Significant improvement of J/sub c/(H) for Nb 3 Al superconducting composites reacted at temperatures above 1800 0 C (to achieve T/sub c/ greater than 17 K) is achieved only by maintaining the layer thickness well below d approximately equal to 1.0 μm

Modern high-temperature superconductivity

International Nuclear Information System (INIS)

Ching Wu Chu

1988-01-01

Ever since the discovery of superconductivity in 1911, its unusual scientific challenge and great technological potential have been recognized. For the past three-quarters of a century, superconductivity has done well on the science front. This is because sueprconductivity is interesting not only just in its own right but also in its ability to act as a probe to many exciting nonsuperconducting phenomena. For instance, it has continued to provide bases for vigorous activities in condensed matter science. Among the more recent examples are heavy-fermion systems and organic superconductors. During this same period of time, superconductivity has also performed admirably in the applied area. Many ideas have been conceived and tested, making use of the unique characteristics of superconductivity - zero resistivity, quantum interference phenomena, and the Meissner effect. In fact, it was not until late January 1987 that it became possible to achieve superconductivity with the mere use of liquid nitrogen - which is plentiful, cheap, efficient, and easy to handle - following the discovery of supercondictivity above 90 K in Y-Ba-Cu-O, the first genuine quaternary superconductor. Superconductivity above 90 K poses scientific and technological challenges not previously encountered: no existing theories can adequately describe superconductivity above 40 K and no known techniques can economically process the materials for full-scale applications. In this paper, therefore, the author recalls a few events leading to the discovery of the new class of quaternary compounds with a superconducting transition temperature T c in the 90 K range, describes the current experimental status of high-temperature superconductivity and, finally, discusses the prospect of very-high-temperature superconductivity, i.e., with a T c substantially higher than 100 K. 97 refs., 7 figs

Size and dimensionality effects in superconducting Mo thin films

International Nuclear Information System (INIS)

Fabrega, L; Gil, O; Camon, A; Parra-BorderIas, M; Fernandez-MartInez, I; Costa-Kraemer, J L; Briones, F; Sese, J; Gonzalez-Arrabal, R

2011-01-01

Molybdenum is a low T c , type I superconductor whose fundamental properties are poorly known. Its importance as an essential constituent of new high performance radiation detectors, the so-called transition edge sensors (TESs) calls for better characterization of this superconductor, especially in thin film form. Here we report on a study of the basic superconducting features of Mo thin films as a function of their thickness. The resistivity is found to rise and the critical temperature decreases on decreasing film thickness, as expected. More relevant, the critical fields along and perpendicular to the film plane are markedly different, thickness dependent and much larger than the thermodynamic critical field of Mo bulk. These results are consistent with a picture of type II 2D superconducting films, and allow estimates of the fundamental superconducting lengths of Mo. The role of morphology in determining the 2D and type II character of the otherwise type I molybdenum is discussed. The possible consequences of this behaviour on the performance of radiation detectors are also addressed.

A novel nuclear-powered propulsion system for ship

International Nuclear Information System (INIS)

Liu Tao; Han Weishi

2003-01-01

A novel nuclear-powered propulsion system for ship is presented in this paper. In this system, a minitype liquid sodium-cooled reactor is used as power; alkali-metal thermal-to-electric conversion (AMTEC) cells are utilized to transform the heat energy to electric energy and superconducting magneto-hydrodynamic (MHD) work as propulsion. This nuclear-powered propulsion system has great advantages in low noise, high speed, long survivability and simple manipulation. It has great significance for the development of propulsion system. (author)

Safety Analysis Report for Packaging (SARP) of the Oak Ridge National Laboratory Shipping Cask D-38. Revision 1

International Nuclear Information System (INIS)

Box, W.D.; Shappert, L.B.; Seagren, R.D.; Watson, C.D.; Hammond, C.R.; Klima, B.B.

1979-09-01

An analytical evaluation of the Oak Ridge National Laboratory Shipping Cask D-38 (solids shipments) was made to demonstrate its compliance with the regulations governing off-site radioactive material shipping packages. The evaluation encompassed five primary categories: structural integrity, thermal resistance, radiation shielding, nuclear criticality safety, and quality assurance. The results of the evaluation show that the cask complies with the applicable regulations

Safety Analysis Report for Packaging (SARP) of the Oak Ridge National Laboratory Shipping Cask D-38. Revision 1

Energy Technology Data Exchange (ETDEWEB)

Box, W.D.; Shappert, L.B.; Seagren, R.D.; Watson, C.D.; Hammond, C.R.; Klima, B.B.

1979-09-01

An analytical evaluation of the Oak Ridge National Laboratory Shipping Cask D-38 (solids shipments) was made to demonstrate its compliance with the regulations governing off-site radioactive material shipping packages. The evaluation encompassed five primary categories: structural integrity, thermal resistance, radiation shielding, nuclear criticality safety, and quality assurance. The results of the evaluation show that the cask complies with the applicable regulations.

Anisotropic superconductivity in β-(BDA-TTP)2SbF6: STM spectroscopy

Science.gov (United States)

Nomura, K.; Muraoka, R.; Matsunaga, N.; Ichimura, K.; Yamada, J.

2009-03-01

We have investigated the gap symmetry in the superconducting phase of β-(BDA-TTP)2SbF6 with use of the scanning tunneling microscope (STM). The tunneling spectra obtained on the conducting surface show a clear superconducting gap structure. Its functional form is of V-shaped similarly to κ-(BEDT-TTF)2X and suggests the anisotropic superconducting gap with line nodes. For lateral surfaces the shape of tunneling spectra varies from the U-shape with relatively large gap to the V-shape with small gap depending on the tunneling direction alternately twice between directional angle 0 and π. From the analysis of conductance curve taking the k dependence of the tunneling probability into account, it is found that the gap has maximum near the a* and c* axes and the nodes appear along near a*+c* and the a-c* directions. These indicate that the d like superconducting pair is formed in this system as the case of κ-(BEDT-TTF)2X. This node direction is consistent with the theoretical prediction based on the spin fluctuation mechanism. However, the zero-bias conductance peak has not been observed yet.

Anisotropic superconductivity in β-(BDA-TTP)2SbF6: STM spectroscopy

International Nuclear Information System (INIS)

Nomura, K.; Muraoka, R.; Matsunaga, N.; Ichimura, K.; Yamada, J.

2009-01-01

We have investigated the gap symmetry in the superconducting phase of β-(BDA-TTP) 2 SbF 6 with use of the scanning tunneling microscope (STM). The tunneling spectra obtained on the conducting surface show a clear superconducting gap structure. Its functional form is of V-shaped similarly to κ-(BEDT-TTF) 2 X and suggests the anisotropic superconducting gap with line nodes. For lateral surfaces the shape of tunneling spectra varies from the U-shape with relatively large gap to the V-shape with small gap depending on the tunneling direction alternately twice between directional angle 0 and π. From the analysis of conductance curve taking the k dependence of the tunneling probability into account, it is found that the gap has maximum near the a* and c* axes and the nodes appear along near a*+c* and the a-c* directions. These indicate that the d x 2 -y 2 like superconducting pair is formed in this system as the case of κ-(BEDT-TTF) 2 X. This node direction is consistent with the theoretical prediction based on the spin fluctuation mechanism. However, the zero-bias conductance peak has not been observed yet

Superconducting Qubit Optical Transducer (SQOT)

Science.gov (United States)

2015-08-05

parts on optical signals and any quasiparticle loss caused by optical photons on microwave signals. Using a superconducting 3D cavity as the microwave...plasmonic and quasiparticle losses. 3. The electro-optic material should be easily integrable with superconducting circuits. A fully integrated

John Bardeen and the theory of superconductivity

International Nuclear Information System (INIS)

Schrieffer, J.R.

1992-01-01

Bardeen's knowledge of the experimental data had bounded the theory of superconductivity quite tightly before B, C and S developed their theory. When one speaks with John Bardeen's friends about him, one frequently hears words such as brilliant, quiet, persistent, generous, visionary, athletic, kind, thoughtful and remarkable. It is the author's good fortune to have the chance to recount some incidents from his life that are connected with the theory of superconductivity. This article draws on the author's personal memories; his many other friends and colleagues will set down their own recollections elsewhere. The evolution of the microscopic theory of superconductivity closely parallels the scientific life of Joh Bardeen. Starting with his PhD dissertation, done under the guidance of Eugene Wigner, he spent much of his life developing an understanding of electron interaction effects and transport properties of metals, semiconductors and superconductors. His fascination with the remarkable phenomenon of superconductivity goes back to his graduate student days at Princeton. Although interrupted during the war years and in the late 1940's at Bell Labs, he returned to this perplexing topic when he moved to the University of Illinois in 1951. 20 refs., 7 figs

Anomalous electron doping independent two-dimensional superconductivity

Science.gov (United States)

Zhou, Wei; Xing, Xiangzhuo; Zhao, Haijun; Feng, Jiajia; Pan, Yongqiang; Zhou, Nan; Zhang, Yufeng; Qian, Bin; Shi, Zhixiang

2017-07-01

Transition metal (Co and Ni) co-doping effects are investigated on an underdoped Ca0.94La0.06Fe2As2 compound. It is discovered that electron doping from substituting Fe with transition metal (TM = Co, Ni) can trigger high-{T}{{c}} superconductivity around 35 K, which emerges abruptly before the total suppression of the innate spin-density-wave/anti-ferromagnetism (SDW/AFM) state. Remarkably, the critical temperature for the high-{T}{{c}} superconductivity remains constant against a wide range of TM doping levels. And the net electron doping density dependence of the superconducting {T}{{c}} based on the rigid band model can be nicely scaled into a single curve for Co and Ni substitutions, in stark contrast to the case of Ba(Fe1-x TM x )2As2. This carrier density independent superconductivity and the unusual scaling behavior are presumably resulted from the interface superconductivity based on the similarity with the interface superconductivity in a La2-x Sr x CuO4-La2CuO4 bilayer. Evidence of the two-dimensional character of the superfluid by angle-resolved magneto-resistance measurements can further strengthen the interface nature of the high-{T}{{c}} superconductivity.

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.

The Kohn-Luttinger mechanism and phase diagram of the superconducting state in the Shubin-Vonsovsky model

International Nuclear Information System (INIS)

Kagan, M. Yu.; Val’kov, V. V.; Mitskan, V. A.; Korovuskin, M. M.

2013-01-01

Using the Shubin-Vonsovsky model in the weak-coupling regime W > U > V (W is the bandwidth, U is the Hubbard onsite repulsion, and V is the Coulomb interaction at neighboring sites) based on the Kohn-Luttinger mechanism, we determined the regions of the existence of the superconducting phases with the d xy , p, s, and d x 2 -y 2 symmetry types of the order parameter. It is shown that the effective interaction in the Cooper channel considerably depends not only on single-site but also on intersite Coulomb correlations. This is demonstrated by the example of the qualitative change and complication of the phase diagram of the superconducting state. The superconducting (SC) phase induction mechanism is determined taking into account polarization contributions in the second-order perturbation theory in the Coulomb interaction. The results obtained for the angular dependence of the superconducting gap in different channels are compared with angule-resolved photoemission spectroscopy (ARPES) results. The influence of long-range hops in the phase diagram and critical superconducting transition temperature in different channels is analyzed. The conditions for the appearance of the Kohn-Luttinger superconductivity with the d x 2 -y 2 symmetry and high critical temperatures T c ∼ 100 K near the half-filling are determined

Inductance calculation of 3D superconducting structures with ground plane

International Nuclear Information System (INIS)

Teh, C.H.; Kitagawa, M.; Okabe, Y.

1999-01-01

An inductance calculation method, which is based on calculating the current distribution of a fluxoid-trapped superconducting loop by using the expression of momentum and the Maxwell equations, is reconstructed to enable calculation of arbitrary 3D structures which have a ground plane (GP). Calculation of the mutual inductances of the superconductor system is also incorporated into the algorithm. The method of images is used to save computational resources, and the mirror plane is demonstrated to be just at the effective penetration depth below the upper boundary of the GP. The algorithm offers accurate results with reasonable calculation time. (author)

Metal-insulator transition and superconductivity in heavily boron-doped diamond and related materials

Energy Technology Data Exchange (ETDEWEB)

Achatz, Philipp

2009-05-15

During this PhD project, the metal-insulator transition and superconductivity of highly boron-doped single crystal diamond and related materials have been investigated. The critical boron concentration n{sub c} for the metal-insulator transition was found to be the same as for the normal-superconductor transition. All metallic samples have been found to be superconducting and we were able to link the occurence of superconductivity to the proximity to the metal-insulator transition. For this purpose, a scaling law approach based on low temperature transport was proposed. Furthermore, we tried to study the nature of the superconductivity in highly boron doped single crystal diamond. Raman spectroscopy measurements on the isotopically substituted series suggest that the feature occuring at low wavenumbers ({approx} 500 cm{sup -1}) is the A1g vibrational mode associated with boron dimers. Usual Hall effect measurements yielded a puzzling situation in metallic boron-doped diamond samples, leading to carrier concentrations up to a factor 10 higher than the boron concentration determined by secondary ion mass spectroscopy (SIMS). The low temperature transport follows the one expected for a granular metal or insulator, depending on the interplay of intergranular and intragranular (tunneling) conductance. The metal-insulator transition takes place at a critical conductance g{sub c}. The granularity also influences significantly the superconducting properties by introducing the superconducting gap {delta} in the grain and Josephson coupling J between superconducting grains. A peak in magnetoresistance is observed which can be explained by superconducting fluctuations and the granularity of the system. Additionally we studied the low temperature transport of boron-doped Si samples grown by gas immersion laser doping, some of which yielded a superconducting transition at very low temperatures. Furthermore, preliminary results on the LO-phonon-plasmon coupling are shown for the

Metal-insulator transition and superconductivity in heavily boron-doped diamond and related materials

International Nuclear Information System (INIS)

Achatz, Philipp

2009-01-01

During this PhD project, the metal-insulator transition and superconductivity of highly boron-doped single crystal diamond and related materials have been investigated. The critical boron concentration n c for the metal-insulator transition was found to be the same as for the normal-superconductor transition. All metallic samples have been found to be superconducting and we were able to link the occurence of superconductivity to the proximity to the metal-insulator transition. For this purpose, a scaling law approach based on low temperature transport was proposed. Furthermore, we tried to study the nature of the superconductivity in highly boron doped single crystal diamond. Raman spectroscopy measurements on the isotopically substituted series suggest that the feature occuring at low wavenumbers (∼ 500 cm -1 ) is the A1g vibrational mode associated with boron dimers. Usual Hall effect measurements yielded a puzzling situation in metallic boron-doped diamond samples, leading to carrier concentrations up to a factor 10 higher than the boron concentration determined by secondary ion mass spectroscopy (SIMS). The low temperature transport follows the one expected for a granular metal or insulator, depending on the interplay of intergranular and intragranular (tunneling) conductance. The metal-insulator transition takes place at a critical conductance g c . The granularity also influences significantly the superconducting properties by introducing the superconducting gap Δ in the grain and Josephson coupling J between superconducting grains. A peak in magnetoresistance is observed which can be explained by superconducting fluctuations and the granularity of the system. Additionally we studied the low temperature transport of boron-doped Si samples grown by gas immersion laser doping, some of which yielded a superconducting transition at very low temperatures. Furthermore, preliminary results on the LO-phonon-plasmon coupling are shown for the first time in aluminum

Specific heat of holmium and YNi{sub 2}B{sub 2}C. Criticalbehaviour and superconducting properties; Spezifische Waerme von Holmium und YNi{sub 2}B{sub 2}C. Kritisches Verhalten und supraleitende Eigenschaften

Energy Technology Data Exchange (ETDEWEB)

Bekkali, Abdelhakim

2010-01-04

Object of the thesis is the study of the specific heat of holmium and YNi{sub 2}B{sub 2}C in the temperature ranges from 50 to 200 KI respectively from 380 mK to 20 K in magnetic fields up to 9 T. In the present thesis the criticalbehaviour of YNi{sub 2}B{sub 2}C and properties of the superconducting state of tne non-magnetic rare-earth nickel borocarbide YNi{sub 2}B{sub 2}C are studied by means of a self-developed measurement apparatur of the specific heat using the quasi-adiabatic heating-pulse method as well as of holmium by means of the relaxation method. In this thesis reliable statements about the critical exponents on monocrystalline holmium could be made. The study on holmium proves that the critical behaviour of the specific heats cannot be described in the framework of the predictions of the chiral universality classes. By means of measurements of the specific heat in this thesis could be confirmed that YNi{sub 2}B{sub 2}C is a multiband superconductor. The positive curvature of the boundary line below T{sub c} in the phase diagram yields a first hint to the many-band character of YNI{sub 2}B{sub 2}C. In the zero-field the electronic specific heat in the superconducting state c{sub es}(T) can be not explained in the framework of the pure BCS theory. At low temperatures a residual contribution by normally conducting electrons could be detected, which hints to a not completely opened energy gap. A possible explanation would be that a band (or several bands) with low charge-carrier concentration not contribute to the superconductivity. This result agrees with de Haas-van Alphen measurements on isostructural superconducting LuNi{sub 2}B{sub 2}C monocrystals, which suggest the many-band character of the superconductivity as well as a vanishing energy gap in one band. The fluctuation behaviour of the specific heat of YNi{sub 2}B{sub 2}C in the neighbourhood of the superconducting-normally conducting transition agrees well with that of the 3D-XY model. [German

SURVEYING, MODELING AND 3D REPRESENTATION OF A WRECK FOR DIVING PURPOSES: CARGO SHIP “VERA”

Directory of Open Access Journals (Sweden)

A. Ktistis

2017-02-01

Full Text Available This paper presents the results from an underwater recording of the stern part of a contemporary cargo-ship wreck. The aim of this survey was to create 3D representations of this wreck mainly for recreational diving purposes. The key points of this paper are: a the implementation of the underwater recording at a diving site; b the reconstruction of a 3d model from data that have been captured by recreational divers; and c the development of a set of products to be used by the general public for the ex situ presentation or for the in situ navigation. The idea behind this project is to define a simple and low cost procedure for the surveying, modeling and 3D representation of a diving site. The perspective of our team is to repeat the proposed methodology for the documentation and the promotion of other diving sites with cultural features, as well as to train recreational divers in underwater surveying procedures towards public awareness and community engagement in the maritime heritage.

Littoral Combat Ship: Knowledge of Survivability and Lethality Capabilities Needed Prior to Making Major Funding Decisions

Science.gov (United States)

2015-12-01

USS Port Royal hit a coral reef in order to provide an independent review of the damage the ship sustained. Our classified report discussed...Improved Weight Management Needed Prior to Further Investments, GAO-14-349SU (Washington, D.C.: Apr. 8, 2014); Littoral Combat Ship: Knowledge of...Early in the program, the Navy decided to forgo a number of traditional ship requirements in order to help reduce the costs and the weight and size

Advanced YBCO-Coated Conductors for Use on Air Platforms (Postprint)

Science.gov (United States)

2007-06-01

for example, the Navy has programs on both homopolar and synchronous superconducting motors to drive the future all-electric ship.6 Westinghouse has...syn- chronous, homopolar , inductor-type alternator with a stationary HTS coil, solid rotor forging, and conven- tional stator; refer to Fig. 1. This is...Denial,’’ III-Vs Rev., 17 [5] 10 (2004). 6. D. U. Gubser, ‘‘Superconducting Motors and Generators for Naval Appli- cations,’’ Physica C, 392–396 1192

Superconducting spin valve effect in Fe/In based heterostructures

Energy Technology Data Exchange (ETDEWEB)

Leksin, Pavel; Schumann, Joachim; Kataev, Vladislav; Schmidt, Oliver; Buechner, Bernd [Leibniz Institute for Solid State and Materials Research IFW Dresden (Germany); Garifyanov, Nadir; Garifullin, Ilgiz [Zavoisky Physical-Technical Institute, Kazan Scientific Center, Russian Academy of Sciences (Russian Federation)

2015-07-01

We report on magnetic and superconducting properties of the spin-valve multilayer system CoOx/Fe1/Cu/Fe2/In. The Superconducting Spin Valve Effect (SSVE) assumes the T{sub c} difference between parallel (P) and antiparallel (AP) orientations of the Fe1 and Fe2 layers' magnetizations. The SSVE value oscillates and changes its sign when the Fe2 layer thickness d{sub Fe2} is varied from 0 to 5 nm. The SSVE value is positive, as expected, in the range 0.4 nm ≤ d{sub Fe2} ≤ 0.8 nm. For a rather broad range of thicknesses 1 nm ≤ d{sub Fe2} ≤ 2.6 nm the SSVE has negative sign assuming the inverse SSVE. Moreover, the magnitude of the inverse effect is larger than that of the positive direct effect. We attribute these oscillations to a quantum interference of the cooper pair wave functions in the magnetic part of the system. For most of the spin-valve samples from this set we experimentally realized the full switching between normal and superconducting states due to direct and inverse SSVE. The analysis of the experimental data has enabled the determination of all microscopic parameters of the studied system.

Possibility of a high-T{sub c} superconducting bulk magnet for maglev trains in the future; Koonchodendo baruku jishaku no jikifujoshiki tetudo heno oyo kanosei

Energy Technology Data Exchange (ETDEWEB)

Fujimoto, H. [Railway Technical Research Institute, Fundamental Research Division, Tokyo (Japan)

1999-11-25

Superconducting magnets made of high-T{sub c} superconductors are promising for industrial applications. It is well known that REBa{sub 2}Cu{sub 3}O{sub 7-x} superconductors prepared by melt processes have a high critical current density, J{sub c}, at 77K and high magnetic fields. The materials are very prospective for high magnetic field application as a superconducting permanent/bulk magnet with liquid-nitrogen refrigeration. LREBaCuO bulks, compared with REBaCuO bulks, exhibit a larger, J{sub c} in high magnetic fields and a much improved irreversibility field, H{sub irr}, at 77K. In this study, we discuss the possibility and trapped field properties of a superconducting bulk magnet, as well as the melt processing for bulk superconductors and their characteristic superconducting and mechanical properties. One of the applications is a superconducting bulk magnet for future magnetically levitated (Maglev) trains. (author)

ShipMo3D Version 3.0 User Manual for Computing Ship Motions in the Time and Frequency Domains

Science.gov (United States)

2012-01-01

permettent de modéliser un navire en manœuvre libre et en eau calme ou dans les vagues. SM3DBuildSeaway construit des modèles de voie maritime à trajet...manœuvrant libre - ment en eau calme ou dans une voie maritime modélisée. Plusieurs applications du logiciel ShipMo3D font des prévisions des mouvements de...files have been removed from this document; however, full sample output files are available for the software . DRDC Atlantic TM 2011-308 1 2 New Features

Surface ferromagnetism and superconducting properties of nanocrystalline niobium nitride

International Nuclear Information System (INIS)

Shipra, R.; Kumar, Nitesh; Sundaresan, A.

2013-01-01

Nanocrystalline δ-NbN x samples have been synthesized by reacting NbCl 5 and urea at three different temperatures. A comparison of their structural, magnetic, transport and thermal properties is reported in the present study. The size of the particles and their agglomeration extent increase with increasing reaction temperature. The sample prepared at 900 °C showed the highest superconducting transition temperature (T c ) of 16.2 K with a transition width, ∼1.8 K, as obtained from the resistivity measurement on cold-pressed bars. Above T c , magnetization measurements revealed the presence of surface ferromagnetism which coexists with superconductivity below T c . Heat capacity measurements confirm superconductivity with strong electron–phonon coupling constant. The sample prepared at 800 °C shows a lower T c (10 K) while that prepared at 700 °C exhibit no superconductivity down to the lowest temperature (3 K) measured. - Highlights: ► Synthesis of δ-NbN nanoparticles by urea nitridation of NbCl 5 . ► Superconducting transition temperature (T c ) is 16.2 K. ► Superconductivity and surface ferromagnetism coexist in the nanoparticles. ► Effect of size and agglomeration on the physical properties of nanoparticles

3D-computation of a thermal process in a superconducting coil

International Nuclear Information System (INIS)

Netter, D.; Leveque, J.; Rezzoug, A.; Caron, J.P.; Sargos, F.M.

1995-01-01

This study deals with the resistive zone propagation in a superconducting coil during a quench, taking into account both the flux density distribution and the anisotropy of the thermal parameters. A Finite Difference Method is used to solve the heat diffusion equation and the flux density is calculated by means of a semi-analytical method. The 3-D model is suitable to describe the quench of thick coils and it can be applied to the study of thermal stability. As an application, a 10 kJ-solenoid is studied

Silicon Hard-Stop Mesas for 3D Integration of Superconducting Qubits

Science.gov (United States)

Kim, David; Rosenberg, Danna; Osadchy, Brenda; Calusine, Greg; Das, Rabindra; Melville, Alexander; Yoder, Jonilyn; Yost, Donna-Ruth; Racz, Livia; Oliver, William

As quantum computing with superconducting qubits advances past the few-qubit stage, implementing 3D packaging/integration to route readout/control lines will become increasingly important. One approach is to bond chips that perform different functions using indium bump bonds. Because indium is malleable, however, achieving the desired spacing and tilt between two chips can be challenging. We present an approach based on etching several microns into the silicon substrate to produce hard stop silicon posts. Since this process involves etching into a pristine substrate, it is essential to evaluate its impact on qubit performance. We report the etched surface's effect on the resonator quality factor and qubit coherence time, as well as the improvement in planarity and tilt. This research was funded in part by the Office of the Director of National Intelligence (ODNI), Intelligence Advanced Research Projects Activity (IARPA) and by the Assistant Secretary of Defense for Research & Engineering 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.

Superconductivity and the structural phase transitions in palladium hydride and palladium deuteride

International Nuclear Information System (INIS)

Standley, R.W.

1980-01-01

The results of two experimental studies of the superconducting transition temperature, T/sub c/, of palladium hydride, PdH/sub x/, and palladium deuteride, PdD/sub x/, are presented. In the first study, the superconducting transition temperature of PdH/sub x/(D/sub x/) is studied as a function of H(D) concentration, x, in the temperature range from 0.2 K to 4K. The data join smoothly with those reported previously by Miller and Satterthwaite at higher temperatures, and the composite data are described by the empirical relation T/sub c/ = 150.8 (x-x/sub o/) 2 244 , where x/sub o/ = 0.715 for hydride samples and 0.668 for deuteride samples. The results, when compared with the theoretical predictions of Klein and Papaconstantopoulos, et al., raise questions about the validity of their explanation of the reverse isotope effect, which is based solely on a difference in force constants. In the second study, the effect of the order-disorder structural transition associated with the 50 K anomaly on the superconductivity of PdH/sub x/(D/sub x/) is investigated. Samples were quenched to low temperatures in the disordered state, and their transition temperatures measured. The samples were then annealed just below the anomaly temperature, and the ordering process followed by monitoring the change in sample resistance. The transition temperatures in the ordered state were then measured

Superconducting Electronic Film Structures

Science.gov (United States)

1991-02-14

Segmuller, A., Cooper, E.I., Chisholm, M.F., Gupta, A. Shinde, S., and Laibowitz, R.B. Lanthanum gallate substrates for epitaxial high-T superconducting thin...M. F. Chisholm, A. Gupta, S. Shinde, and R. B. Laibowitz, " Lanthanum Gallate Substrates for Epitaxial High-T c Superconducting Thin Films," Appl...G. Forrester and J. Talvacchio, " Lanthanum Copper Oxide Buffer Layers for Growth of High-T c Superconductor Films," Disclosure No. RDS 90-065, filed

Superconducting magnets for toroidal fusion reactors

International Nuclear Information System (INIS)

Haubenreich, P.N.

1980-01-01

Fusion reactors will soon be employing superconducting magnets to confine plasma in which deuterium and tritium (D-T) are fused to produce usable energy. At present there is one small confinement experiment with superconducting toroidal field (TF) coils: Tokamak 7 (T-7), in the USSR, which operates at 4 T. By 1983, six different 2.5 x 3.5-m D-shaped coils from six manufacturers in four countries will be assembled in a toroidal array in the Large Coil Test Facility (LCTF) at Oak Ridge National Laboratory (ORNL) for testing at fields up to 8 T. Soon afterwards ELMO Bumpy Torus (EBT-P) will begin operation at Oak Ridge with superconducting TF coils. At the same time there will be tokamaks with superconducting TF coils 2 to 3 m in diameter in the USSR and France. Toroidal field strength in these machines will range from 6 to 9 T. NbTi and Nb 3 Sn, bath cooling and forced flow, cryostable and metastable - various designs are being tried in this period when this new application of superconductivity is growing and maturing

Ex-situ manufacturing of SiC-doped MgB2 used for superconducting wire in medical device applications

Science.gov (United States)

Herbirowo, Satrio; Imaduddin, Agung; Sofyan, Nofrijon; Yuwono, Akhmad Herman

2017-02-01

Magnesium diboride (MgB2) is a superconductor material with a relatively high critical temperature. Due to its relatively high critical temperature, this material is promising and has the potential to replace Nb3Sn for wire superconducting used in many medical devices. In this work, nanoparticle SiC-doped MgB2 superconducting material has been fabricated through an ex-situ method. The doping of nanoparticle SiC by 10 and 15 wt% was conducted to analyze its effect on specific resistivity of MgB2. The experiment was started by weighing a stoichiometric amount of MgB2 and nanoparticles SiC. Both materials were mixed and grounded for 30 minutes by using an agate mortar. The specimens were then pressed into a 6 mm diameter stainless steel tube, which was then reduced until 3 mm through a wire drawing method. X-ray diffraction analysis was conducted to confirm the phase, whereas the superconductivity of the specimens was analyzed by using resistivity measurement under cryogenic magnetic system. The results indicated that the commercial MgB2 showed a critical temperature of 37.5 K whereas the SiC doped MgB2 has critical temperature of 38.3 K.

High-T{sub c} superconductivity in monolayer FeSe on SrTiO{sub 3} via interface-induced small-q electron-phonon coupling

Energy Technology Data Exchange (ETDEWEB)

Aperis, Alexandros; Oppeneer, Peter M. [Uppsala University (Sweden)

2016-07-01

A monolayer of FeSe deposited on SrTiO{sub 3} becomes superconducting at temperatures that exceed T{sub c}=100 K, as compared to a bulk T{sub c} of 8 K. Recent ARPES measurements have provided strong evidence that an interfaced-induced electron-phonon interaction between FeSe electrons and SrTiO{sub 3} phonons plays a decisive role in this phenomenon. However, the mechanism that drives this tantalizing high-T{sub c} boost is still unclear. Here, we examine the recent experimental findings using fully anisotropic, full bandwidth multiband Eliashberg calculations focusing on the superconducting state of FeSe/STO. We use a realistic ten band tight-binding band structure for the electrons of monolayer FeSe and study how the suggested interface-induced small-q electron-phonon interaction mediates superconductivity. Our calculations produce a high-T{sub c} s-wave superconducting state with the experimentally resolved momentum dependence. Further, we calculate the normal metal/insulator/superconductor tunneling spectrum and identify fingerprints of the interface-induced phonon mechanism.

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.

The Kohn-Luttinger mechanism and phase diagram of the superconducting state in the Shubin-Vonsovsky model

Energy Technology Data Exchange (ETDEWEB)

Kagan, M. Yu., E-mail: kagan@kapitza.ras.ru [Russian Academy of Sciences, Kapitza Institute for Physical Problems (Russian Federation); Val' kov, V. V.; Mitskan, V. A.; Korovuskin, M. M. [Russian Academy of Sciences, Kirenskii Physics Institute, Siberian Branch (Russian Federation)

2013-10-15

Using the Shubin-Vonsovsky model in the weak-coupling regime W > U > V (W is the bandwidth, U is the Hubbard onsite repulsion, and V is the Coulomb interaction at neighboring sites) based on the Kohn-Luttinger mechanism, we determined the regions of the existence of the superconducting phases with the d{sub xy}, p, s, and d{sub x{sup 2}-y{sup 2}} symmetry types of the order parameter. It is shown that the effective interaction in the Cooper channel considerably depends not only on single-site but also on intersite Coulomb correlations. This is demonstrated by the example of the qualitative change and complication of the phase diagram of the superconducting state. The superconducting (SC) phase induction mechanism is determined taking into account polarization contributions in the second-order perturbation theory in the Coulomb interaction. The results obtained for the angular dependence of the superconducting gap in different channels are compared with angule-resolved photoemission spectroscopy (ARPES) results. The influence of long-range hops in the phase diagram and critical superconducting transition temperature in different channels is analyzed. The conditions for the appearance of the Kohn-Luttinger superconductivity with the d{sub x{sup 2}-y{sup 2}} symmetry and high critical temperatures T{sub c} {approx} 100 K near the half-filling are determined.

Superconductivity in doped Dirac semimetals

Science.gov (United States)

Hashimoto, Tatsuki; Kobayashi, Shingo; Tanaka, Yukio; Sato, Masatoshi

2016-07-01

We theoretically study intrinsic superconductivity in doped Dirac semimetals. Dirac semimetals host bulk Dirac points, which are formed by doubly degenerate bands, so the Hamiltonian is described by a 4 ×4 matrix and six types of k -independent pair potentials are allowed by the Fermi-Dirac statistics. We show that the unique spin-orbit coupling leads to characteristic superconducting gap structures and d vectors on the Fermi surface and the electron-electron interaction between intra and interorbitals gives a novel phase diagram of superconductivity. It is found that when the interorbital attraction is dominant, an unconventional superconducting state with point nodes appears. To verify the experimental signature of possible superconducting states, we calculate the temperature dependence of bulk physical properties such as electronic specific heat and spin susceptibility and surface state. In the unconventional superconducting phase, either dispersive or flat Andreev bound states appear between point nodes, which leads to double peaks or a single peak in the surface density of states, respectively. As a result, possible superconducting states can be distinguished by combining bulk and surface measurements.

Dependence of the superconducting transition temperature of the filled skutterudite compound PrPt{sub 4}Ge{sub 12} on hydrostatic pressure

Energy Technology Data Exchange (ETDEWEB)

Foroozani, N. [Department of Physics, Washington University, St. Louis, MO 63130 (United States); Hamlin, J.J. [Department of Physics, University of California, San Diego, La Jolla, CA 92093 (United States); Schilling, J.S., E-mail: jss@wuphys.wustl.edu [Department of Physics, Washington University, St. Louis, MO 63130 (United States); Baumbach, R.E.; Lum, I.K.; Shu, L.; Huang, K.; Maple, M.B. [Department of Physics, University of California, San Diego, La Jolla, CA 92093 (United States)

2013-02-14

Highlights: ► Superconductivity in the filled skutterudite PrPt{sub 4}Ge{sub 12}. ► Dependence of T{sub c} on purely hydrostatic pressure to 0.6 GPa. ► Comparison of lattice pressure to external pressure effects on superconductivity. ► Evidence for magnetic pair-breaking effects. -- Abstract: The temperature-dependent ac susceptibility of the filled skutterudite superconductor PrPt{sub 4}Ge{sub 12} has been measured under hydrostatic He-gas pressure to 0.58 GPa. The superconducting transition temperature T{sub c} decreases linearly with pressure P from 7.91 K at ambient pressure to 7.83 K at 0.58 GPa, giving the rate dT{sub c}/dP = −0.19 ± 0.03 K/GPa. Evidence is presented that suggests that the value of T{sub c} in this compound is slightly reduced due to magnetic pair-breaking effects from the Pr{sup 3+} cations.

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

International Nuclear Information System (INIS)

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

2012-01-01

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

Superconductivity at the industrial scale

International Nuclear Information System (INIS)

Tixador, P.; Lebrun, Ph.

2011-01-01

The discovery of superconductivity is 100 years old but theoretical works are still necessary: the BCS theory does not apply to the new families of high temperature superconducting materials discovered after 1986. In 2001 it was discovered that MgB 2 is superconducting at 39 K, this critical temperature is not the highest but MgB 2 is easy to produce and cheap. Today's highest critical temperature under atmospheric pressure is that of the HgTlBaCaCuO compound: 138 K. The complexity and the cost of cryogenic systems restrain the applications of superconductivity. The author reviews the applications of superconducting in medical imaging, particle detectors, and in the safety systems of power networks. (A.C.)

Magnetism and superconductivity in Eu(Ho)Mo/sub 6/S/sub 8/

Energy Technology Data Exchange (ETDEWEB)

Capone, D.W. II; Lai Fook, M.S.; Guertin, R.P.; Hinks, D.G.; Dunlap, B.D.; Foner, S.; Abou-Aly, A.I.; Brooks, J.S.

1984-10-01

A variety of ambient and high pressure experimental results reveal the interplay between magnetism and superconductivity in Ho doped samples of the pressure induced superconductor, EuMo/sub 6/S/sub 8/. Ho concentrations up to 50 atomic percent of the rare earth ions were used. High resolution magnetic measurements are consistent with the crystalline electric field ground state for the Ho/sup 3 +/ ions being a magnetic doublet consisting largely of J/sub z/ = 18. The results of high pressure magnetization experiments reveal negligible effects of reduced lattice constant on the rare earth-rare earth interactions. Resistivity in a 10 atomic percent sample for P = 10 kbar shows the suppression of a P = 0 structural transition, metallic conductivity down to low temperatures, and finally superconductivity at 8 K. The upper critical field, H/sub c2/(T), for this sample was measured for P = 7, 10 and 12 kbar and showed strong reentrant behavior (dH/sub c2/(T)/dT > 0 as T ..-->.. 0 K). A minimum with field in the resistivity above H/sub c2/ was also observed at lowest temperatures. The H/sub c2/(T) data are compared with those of EuMo/sub 6/S/sub 8/ at high pressure, which shows positive curvature, and HoMo/sub 6/S/sub 8/, in which superconductivity is quenched by ferromagnetism at low temperatures. 14 references, 4 figures.

Superconductivity in doped two-leg ladder cuprates

International Nuclear Information System (INIS)

Qin Jihong; Yuan Feng; Feng Shiping

2006-01-01

Within the t-J ladder model, superconductivity with a modified d-wave symmetry in doped two-leg ladder cuprates is investigated based on the kinetic energy driven superconducting mechanism. It is shown that the spin-liquid ground-state at the half-filling evolves into the superconducting ground-state upon doping. In analogy to the doping dependence of the superconducting transition temperature in the planar cuprate superconductors, the superconducting transition temperature in doped two-leg ladder cuprates increases with increasing doping in the underdoped regime, and reaches a maximum in the optimal doping, then decreases in the overdoped regime

{sup 119}Sn-NMR investigations on superconducting Ca{sub 3}Ir{sub 4}Sn{sub 13}: Evidence for multigap superconductivity

Energy Technology Data Exchange (ETDEWEB)

Sarkar, R., E-mail: rajibsarkarsinp@gmail.com [Institute for Solid State Physics, TU Dresden, D-01069 Dresden (Germany); Brückner, F.; Günther, M. [Institute for Solid State Physics, TU Dresden, D-01069 Dresden (Germany); Wang, Kefeng; Petrovic, C. [Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, NY 11973 (United States); Biswas, P.K.; Luetkens, H.; Morenzoni, E.; Amato, A. [Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institute, CH-5232 Villigen PSI (Switzerland); Klauss, H-H. [Institute for Solid State Physics, TU Dresden, D-01069 Dresden (Germany)

2015-12-15

We report bulk superconductivity (SC) in Ca{sub 3}Ir{sub 4}Sn{sub 13} by means of {sup 119}Sn nuclear magnetic resonance (NMR) experiments. Two classical signatures of BCS superconductivity in spin-lattice relaxation rate (1/T{sub 1}), namely the Hebel–Slichter coherence peak just below the T{sub c}, and the exponential decay in the superconducting phase, are evident. The noticeable decrease of {sup 119}Sn Knight shift below T{sub c} indicates spin-singlet superconductivity. The temperature dependence of the spin-lattice relaxation rate {sup 119}(1/T{sub 1}) is convincingly described by the multigap isotropic superconducting gap. NMR experiments do not witness any sign of enhanced spin fluctuations.

Superatom representation of high-T{sub C} superconductivity

Energy Technology Data Exchange (ETDEWEB)

Panas, Itai, E-mail: itai@chalmers.se [Environmental Inorganic Chemistry, Division of Energy and Materials, Department of Chemistry and Biotechnology, Chalmers University of Technology, S-412 96 Gothenburg (Sweden)

2012-10-15

A 'super-atom' conceptual interface between chemistry and physics is proposed in order to assist in the search for higher T{sub C} superconductors. The plaquettes generating the checkerboard superstructure in the cuprates, the C{sub 60} molecules in K{sub 3}C{sub 60}, and the Mo{sub 6}S{sub 8}{sup 2-} clusters in Chevrel phase materials offer such candidate super-atoms. Thus, in the present study high-T{sub C} superconductivity HTSC is articulated as the entanglement of two disjoint electronic manifolds in the vicinity of a common Fermi energy. The resulting HTSC ground state couples near-degenerate protected local super-atom states to virtual magnons in an antiferromagnetic AFM embedding. The composite Cooper pairs emerge as the interaction particles for virtual magnons mediated 'self-coherent entanglement' of super-atom states. A Hueckel type resonating valence bond RVB formalism is employed in order to illustrate the real-space Cooper pairs as well as their delocalization and Bose Einstein condensation BEC on a ring of super-atoms. The chemical potential {mu}{sub BEC} for Cooper pairs joining the condensate is formulated in terms of the super-exchange interaction, and consequently the T{sub C} in terms of the Neel temperature. A rationale for the robustness of the HTSC ground state is proposed: achieving local maximum 'electron correlation entropy' at the expense of non-local phase rigidity.

High-temperature superconducting oxide synthesis and the chemical doping of the Cu-O planes

International Nuclear Information System (INIS)

Tarascon, J.M.; Barboux, P.; Bagley, B.G.; Greene, L.H.; McKinnon, W.R.; Hull, G.W.

1987-01-01

Different synthesis techniques for the preparation of dense superconducting ceramics are discussed, and a sol-gel process is shown to be very promising. The effect of oxygen content, and the effect of substitution of Ni and Zn for copper, on the structural, transport and superconducting properties of the La-Sr-Cu-O and Y-Ba-Cu-O systems are presented. The authors find that substitution on the copper sites destroys T/sub c/ in the La-Sr-Cu-O system and decreases it in the Y-Ba-Cu-O system, and this effect is insensitive as to whether the 3d metal is magnetic (Ni) or diamagnetic (Zn). A detailed study of the YBa/sub 2/Cu/sub 3/O/sub 7-y/ system as a function of oxygen content (y) shows that superconductivity can be destroyed in these materials by the removal of oxygen and restored by reinjecting oxygen; either thermally at 500 0 C or at temperatures (80 0 C) compatible with device processing by means of a novel plasma oxidation process. Of scientific interest, the plasma process induces bulk superconductivity in the undoped La/sub 2/CuO/sub 4/

Experimental Observation of Non-'S-Wave' Superconducting Behavior in Bulk Superconducting Tunneling Junctions of Yba2Cu3O7-δ

Directory of Open Access Journals (Sweden)

Leandro Jose Guerra

1998-06-01

Full Text Available Evidence of non-s-wave superconductivity from normal tunneling experiments in bulk tunneling junctions of YBa2Cu3O7-δ is presented. The I-V and dI/dV characteristics of bulk superconducting tunneling junctions of YBa2Cu3O7-δ have been measured at 77.0K and clear deviation from s-wave superconducting behavior has been observed. The result agrees with d-wave symmetry, and interpreting the data in this way, the magnitude of the superconducting energy gap, 2Δ, is found to be (0.038 ± 0.002 eV. Comparing this energy gap with Tc (2Δ/kB Tc = 5.735, indicates that these high-Tc superconductors are strongly correlated materials, which in contrast with BCS-superconductors are believed to be weakly correlated.

Recent progress towards developing a high-field, high-T(sub c) superconducting magnet for magnetic suspension and balance systems

International Nuclear Information System (INIS)

Derochemont, L.P.; Oakes, C.E.; Squillante, M.R.; Duan, Hong-Min; Hermann, A.M.; Andrews, R.J.; Poeppel, R.B.; Maroni, V.A.; Carlberg, I.A.; Kelliher, W.C.

1992-01-01

This paper reviews superconducting magnets and high T(sub c) superconducting oxide ceramic materials technology to identify areas of fundamental impasse to the fabrication of components and devices that tap what are believed to be the true potential of these new materials. High T(sub c) ceramics pose problems in fundamentally different areas which need to be solved unlike low T(sub c) materials. The authors map out an experimental plan designed to research process technologies which, if suitably implemented, should allow these deficiencies to be solved. Finally, assessments are made of where and on what regimes magnetic system designers should focus their attention to advance the practical development of systems based on these new materials

Recent progress towards developing a high field, high-T(sub c) superconducting magnet for magnetic suspension and balance systems

Science.gov (United States)

Derochemont, L. Pierre; Oakes, Carlton E.; Squillante, Michael R.; Duan, Hong-Min; Hermann, Allen M.; Andrews, Robert J.; Poeppel, Roger B.; Maroni, Victor A.; Carlberg, Ingrid A.; Kelliher, Warren C.

1992-01-01

This paper reviews superconducting magnets and high T(sub c) superconducting oxide ceramic materials technology to identify areas of fundamental impasse to the fabrication of components and devices that tap what are believed to be the true potential of these new materials. High T(sub c) ceramics pose problems in fundamentally different areas which need to be solved unlike low T(sub c) materials. The authors map out an experimental plan designed to research process technologies which, if suitably implemented, should allow these deficiencies to be solved. Finally, assessments are made of where and on what regimes magnetic system designers should focus their attention to advance the practical development of systems based on these new materials.

Tunneling observation at very low temperature of impurity bands within the gap of the Kondo superconducting system CuFe/Pb(T(K)>T(c))

International Nuclear Information System (INIS)

Dumoulin, Louis; Le Fur, Daniel

1976-01-01

Very low temperature superconducting tunneling experiments on CuFe(12.10 -6 ) backed by superconducting lead show a band of localized states next to the gap edge. There is no quantitative agreement with the perturbative approach of Mueller-Hartmann Zittartz in this system where the Kondo temperature is larger than the superconductive T(c) [fr

Random errors in the magnetic field coefficients of superconducting magnets

International Nuclear Information System (INIS)

Herrera, J.; Hogue, R.; Prodell, A.; Wanderer, P.; Willen, E.

1985-01-01

Random errors in the multipole magnetic coefficients of superconducting magnet have been of continuing interest in accelerator research. The Superconducting Super Collider (SSC) with its small magnetic aperture only emphasizes this aspect of magnet design, construction, and measurement. With this in mind, we present a magnet model which mirrors the structure of a typical superconducting magnet. By taking advantage of the basic symmetries of a dipole magnet, we use this model to fit the measured multipole rms widths. The fit parameters allow us then to predict the values of the rms multipole errors expected for the SSC dipole reference design D, SSC-C5. With the aid of first-order perturbation theory, we then give an estimate of the effect of these random errors on the emittance growth of a proton beam stored in an SSC. 10 refs., 6 figs., 2 tabs

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.

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

Global Shipping Game

Science.gov (United States)

2011-01-28

information please contact the Chairman, War Gaming Department, Naval War College, 686 Cushing Road, Newport, RI 02841 or via electronic mail at... Game ……………………………………………...9 c. Overarching Research Question……………………………………………..…10 d. Subsidiary Questions…………………………………………………………...10 e ...An e -SLOC is the “cyber network that supports the global maritime trade network.” Industry Global Shipping Game Report 27 experts felt that

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

Rigorous study of the gap equation for an inhomogeneous superconducting state near T/sub c/

International Nuclear Information System (INIS)

Hu, C.

1975-01-01

A rigorous analytic study of the self-consistent gap equation (symobolically Δ=F/sub T/Δ), for an inhomogeneous superconducting state, is presented in the Bogoliubov formulation. The gap function Δ (r) is taken to simulate a planar normal-superconducting phase boundary: Δ (r) =Δ/sub infinity/ tanh(αΔ/sub infinity/z/v/sub F/) THETA (z), where Δ/sub infinity/(T) is the equilibrium gap, v/subF/ is the Fermi velocity, and THETA (z) is a unit step function. First a special space integral of the gap equation proportional∫ 0 /sub +//sup infinity/(F/sub T/-Δ)(dΔ/dz) dz is evaluated essentially exactly, except for a nonperturbative WKBJ approximation used in solving the Bogoliubov--de Gennes equations. It is then expanded near the transition temperature T/sub c/ in power of Δ/sub infinity/proportional (1-T/T/sub c/) 1 / 2 , demonstrating an exact cancellation of a subseries of ''anomalous-order'' terms. The leading surviving term is found to agree in order, but not in magnitude, with the Ginzburg-Landau-Gor'kov (GLG) approximation. The discrepancy is found to be linked to the slope discontinuity in our chosen Δ. A contour-integral technique in a complex-energy plane is then devised to evaluate the local value of F/sub T/-Δ exactly. Our result reveals that near T/sub c/ this method can reproduce the GLG result essentially everywhere, except within a BCS coherence length not xi (T) exclamation from a singularity in Δ, where F/sub T/-Δ can have a singular contribution with an ''anomalous'' local magnitude, not expected from the GLG approach. This anomalous term precisely accounts for the discrepancy found in the special integral of the gap equation as mentioned above, and likely explains the ultimate origin of the anomalous terms found in the free energy of an isolated vortex line by Cleary

Two band superconductivity for MgB{sub 2}: T{sub c} and isotope exponent {alpha} as a function of the carrier number n and the role of the center of the band

Energy Technology Data Exchange (ETDEWEB)

Rodriguez-Nunez, J J [Lab. SUPERCOMP, Departamento de Fisica - FACYT - UC, Valencia (Venezuela) and Abdus Salam International Centre for Theoretical Physics, Trieste (Italy); Schmidt, A A [Departamento de Matematica, UFSM, Santa Maria, RS (Brazil); Bianconi, A [Physics Department, Universita di Roma, Rome (Italy); Perali, A [Physics Department, University of Camerino, Camerino - MC (Italy)

2005-08-15

We study a two band superconducting, assuming that we have two tight binding bands, {epsilon}{sub 2}(k-vector) = {epsilon}{sub 2}{sup (0)} - t{sub 2}[cos(k{sub x}) + cos(k{sub y}) + s{sub 2} cos(k{sub z})] - {mu} and {epsilon}{sub 3}(k-vector) {epsilon}{sub 3}{sup (0)} - t{sub 3} [cos(k{sub x}) + cos(k{sub y})+s{sub 3} cos(k{sub z})] - {mu}. We solve the two gap equations at T = T{sub c} and calculate T{sub c} x n and {mu} x n for various values of pairing interaction, V, and Debye frequency, {omega}{sub D}. Also, from an expression developed in a previous paper by two of the present authors, we calculate {alpha} x n, where n is the number of carriers per site per band and {alpha} is the isotope exponent. We take only interband scattering, V, as a first approach. We find that in order to have superconductivity (T{sub c} {ne} 0), large values of V are necessary. Also, for V/{omega}{sub D} > 1, we obtain {alpha} > 1.00 and for V/{omega}{sub D}>1.00, the isotope exponent becomes less than 1. (author)

27 CFR 44.187 - Shipping containers.

Science.gov (United States)

2010-04-01

... 27 Alcohol, Tobacco Products and Firearms 2 2010-04-01 2010-04-01 false Shipping containers. 44... Shipping containers. Each shipping case, crate, or other container in which tobacco products, or cigarette... same containers in which they were received from the factory. (72 Stat. 1418, as amended; 26 U.S.C...

FY 2000 research and development of fundamental technologies for AC superconducting power devices. R and D of fundamental technologies for superconducting power cables and faults current limiters, R and D of superconducting magnets for power applications, and study on the total systems and related subjects; 2000 nendo koryu chodendo denryoku kiki kiban gijutsu kenkyu kaihatsu seika hokokusho. Chodendo soden cable kiban gijutsu no kenkyu kaihatsu, chodendo genryuki kiban gijutsu no kenkyu kaihatsu, denryokuyo chodendo magnet no kenkyu kaihatsu, total system nado no kenkyu

Energy Technology Data Exchange (ETDEWEB)

NONE

2001-03-01

The project for research and development of fundamental technologies for AC superconducting power devices has been started, and the FY 2000 results are reported. The R and D of fundamental technologies for superconducting power cables include grasping the mechanical characteristics associated with integration necessary for fabrication of large current capacity and long cables; development of barrier cable materials by various methods; and development of short insulated tubes as cooling technology for long superconducting cables, and grasping its thermal/mechanical characteristics. The R and D of faults current limiters include introduction of the unit for superconducting film fabrication, determination of the structures and layouts for large currents, and improvement of performance of each device for high voltages. R and D of superconducting magnets for power applications include grasping the fundamental characteristics of insulation at cryogenic temperature, completion of the insulation designs for high voltage/current lead bushing, and development of prototype sub-cooled nitrogen cooling unit for cooling each AC power device. Study on the total systems and related subjects include analysis for stabilization of the group model systems, to confirm improved voltage stability when the superconducting cable is in service. (NEDO)

Advanced Demonstration of Motion Correction for Ship-to-Ship Passive Inspections

Energy Technology Data Exchange (ETDEWEB)

Ziock, Klaus-Peter [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Boehnen, Chris Bensing [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Ernst, Joseph [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

2013-09-30

Passive radiation detection is a key tool for detecting illicit nuclear materials. In maritime applications it is most effective against small vessels where attenuation is of less concern. Passive imaging provides: discrimination between localized (threat) and distributed (non-threat) sources, removal of background fluctuations due to nearby shorelines and structures, source localization to an individual craft in crowded waters, and background subtracted spectra. Unfortunately, imaging methods cannot be easily applied in ship-to-ship inspections because relative motion of the vessels blurs the results over many pixels, significantly reducing sensitivity. This is particularly true for the smaller water craft where passive inspections are most valuable. In this project we performed tests and improved the performance of an instrument (developed earlier under, “Motion Correction for Ship-to-Ship Passive Inspections”) that uses automated tracking of a target vessel in visible-light images to generate a 3D radiation map of the target vessel from data obtained using a gamma-ray imager.

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.

On the interplay of superconductivity and magnetism

International Nuclear Information System (INIS)

Powell, Benjamin James

2002-01-01

We explore the exchange field dependence of the Hubbard model with a attractive, effective, pairwise, nearest neighbour interaction via the Hartree-Fock-Gorkov approximation. We derive a Ginzburg-Landau theory of spin triplet superconductivity in an exchange field. For microscopic parameters which lead to ABM phase superconductivity in zero field, the Ginzburg-Landau theory allows both an axial (A, A 1 or A 2 ) solution with the vector order parameter, d(k), perpendicular to the field, H, and an A phase solution with d(k) parallel to H. We study the spin-generalised Bogoliubov-de Gennes (BdG) equations for this model with parameters suitable for strontium ruthenate (Sr 2 RuO 4 ). The A 2 phase is found to be stable in a magnetic field. However, in the real material, spin-orbit coupling could pin the order parameter to the crystallographic c-axis which would favour the A phase for fields parallel to the c-axis. We show that the low temperature thermodynamic behaviour in a magnetic field could experimentally differentiate between these two possible behaviours. Further we show that this pinning could cause a Freedericksz (Frederiks) transition in bulk Sr 2 RuO 4 (Freedericksz transitions have only previously been seen in confined geometries.) We calculate the superconducting critical temperature, T C , of ZrZn 2 in the presence of non-magnetic impurity scattering from the Abrikosov-Gorkov formula. Residual resistivity experiments indicate that the transition temperature in the absence of impurity scattering, T CO = 1.15 ± 0.15 K, while de Haas-van Alphen experiments give T CO ∼ 3 K. We discuss this disagreement and conclude that the former estimate is the more reliable. We derive the equal spin pairing (ESP) gap equations for a ferromagnetic superconductor, which we solve for parameters chosen for ZrZn 2 . We show that for ESP states in a ferromagnetic superconductor, in the absence of spin flip processes, the two spin states are separate subsystems due to exchange

Changes of superconducting interaction in interfaces

International Nuclear Information System (INIS)

Halbritter, J.

1976-01-01

The leakage of conduction electrons from metals into dielectric or semiconducting coatings yields changes in electron phonon coupling and hybridization with localized states in the coating. The changed electron-phonon coupling explains the observed strengthened superconducting interaction with some monolayer thick coating. The hybridization with localized states, i.e. resonance scattering, yields pair weakening and hence a monotonic depression of superconductivity with coating thickness in agreement with experiments. The latter effect explains quantitatively the Tsub(c) and Δ depression (Δ/kTsub(c) approximately equal to const) and a decrease in the Maki-Thompson-fluctuation term observed with thin superconducting films. (author)

Calculations of resistivity and superconducting T/sub c/ in transition metals

International Nuclear Information System (INIS)

Allen, P.B.; Beaulac, T.P.; Khan, F.S.; Butler, W.H.; Pinski, F.J.; Swihart, J.C.

1985-01-01

A survey is given of various electron-phonon effects which have been calculated for the metals Nb, Mo, Ta, Pd, and Cu. These effects include the mass enhancement λ, superconducting T/sub c/, electrical and thermal resistivity, Hall coefficient, magnetoresistance, and the successfully tested predictions of linewidths γ 0 of phonons. The calculations use local density approximations (LDA) energy bands, experimental phonons, and the rigid muffin tin (RMT) approximation. Mesh size noise is less than 1% and the Bloch-Boltzmann integral equation has been solved to unprecedented accuracy

Interface-Induced Zeeman-Protected Superconductivity in Ultrathin Crystalline Lead Films

Science.gov (United States)

Liu, Yi; Wang, Ziqiao; Zhang, Xuefeng; Liu, Chaofei; Liu, Yongjie; Zhou, Zhimou; Wang, Junfeng; Wang, Qingyan; Liu, Yanzhao; Xi, Chuanying; Tian, Mingliang; Liu, Haiwen; Feng, Ji; Xie, X. C.; Wang, Jian

2018-04-01

Two-dimensional (2D) superconducting systems are of great importance for exploring exotic quantum physics. The recent development of fabrication techniques has stimulated studies of high-quality single-crystalline 2D superconductors, where intrinsic properties give rise to unprecedented physical phenomena. Here, we report the observation of Zeeman-type spin-orbit interaction protected superconductivity (Zeeman-protected superconductivity) in 4-monolayer (ML) to 6-ML crystalline Pb films grown on striped incommensurate Pb layers on Si(111) substrates by molecular beam epitaxy. An anomalously large in-plane critical field far beyond the Pauli limit is detected, which can be attributed to the Zeeman-protected superconductivity due to the in-plane inversion symmetry breaking at the interface. Our work demonstrates that, in superconducting heterostructures, the interface can induce Zeeman-type spin-orbit interactions and modulate the superconductivity.

Materials and mechanisms of hole superconductivity

Energy Technology Data Exchange (ETDEWEB)

Hirsch, J.E., E-mail: jhirsch@ucsd.edu [Department of Physics, University of California, San Diego, La Jolla, CA 92093-0319 (United States)

2012-01-15

We study the applicability of the model of hole superconductivity to materials. Both conventional and unconventional materials are considered. Many different classes of materials are discussed. The theory is found suitable to describe all of them. No other theory of superconductivity can describe all these classes of materials. The theory of hole superconductivity proposes that there is a single mechanism of superconductivity that applies to all superconducting materials. This paper discusses several material families where superconductivity occurs and how they can be understood within this theory. Materials discussed include the elements, transition metal alloys, high T{sub c} cuprates both hole-doped and electron-doped, MgB{sub 2}, iron pnictides and iron chalcogenides, doped semiconductors, and elements under high pressure.

Superconductivity and the environment: a Roadmap

International Nuclear Information System (INIS)

Nishijima, Shigehiro; Eckroad, Steven; Marian, Adela; Choi, Kyeongdal; Kim, Woo Seok; Terai, Motoaki; Deng, Zigang; Zheng, Jun; Wang, Jiasu; Umemoto, Katsuya; Du, Jia; Keenan, Shane; Foley, Cathy P; Febvre, Pascal; Mukhanov, Oleg; Cooley, Lance D; Hassenzahl, William V; Izumi, Mitsuru

2013-01-01

greenhouse gas emissions according to the Kyoto Protocol (Hartikainen et al 2003 Supercond. Sci. Technol. 16 963). New technologies would include superconducting energy storage systems to effectively store power generation from renewable sources as well as high-temperature superconducting systems used in generators, transformers and synchronous motors in power stations and heavy-industry facilities. However, to be effective, these systems must be superior to conventional systems and, in reality, market penetration will occur as existing electrical machinery is written off. At current write-off rates, to achieve a 50% transfer to superconducting systems will take 20 years (Hartikainen et al 2003 Supercond. Sci. Technol. 16 963). The Roadmap next considers dc transmission of green power with a section by Eckroad and Marian who provide an update on the development of superconducting power transmission lines in view of recent sustainability studies. The potential of magnetic energy storage is then presented by Coi and Kim, who argue that a successful transition to wind and solar power generation must be harmonized with the conventional electrical network, which requires a storage technology with a fast response and long backup times. Transport. Superconducting Maglev trains and motors for international shipping have the potential to considerably reduce the emissions that contribute to greenhouse gases while improving their economic viability by reducing losses and improving efficiencies. International shipping, alone, contributes 3% of the greenhouse gas emissions. Three sections of the Roadmap identify how high-speed rail can be a major solution to providing fast, low energy, environmentally-friendly transport enabling reduction in automobile and aircraft travel by offering an alternative that is very competitive. With maritime international environmental regulations tightening, HTS motors with the characteristics of high torque and compactness will become important devices for

Superconductivity and the environment: a Roadmap

Science.gov (United States)

Nishijima, Shigehiro; Eckroad, Steven; Marian, Adela; Choi, Kyeongdal; Kim, Woo Seok; Terai, Motoaki; Deng, Zigang; Zheng, Jun; Wang, Jiasu; Umemoto, Katsuya; Du, Jia; Febvre, Pascal; Keenan, Shane; Mukhanov, Oleg; Cooley, Lance D.; Foley, Cathy P.; Hassenzahl, William V.; Izumi, Mitsuru

2013-11-01

gas emissions according to the Kyoto Protocol (Hartikainen et al 2003 Supercond. Sci. Technol. 16 963). New technologies would include superconducting energy storage systems to effectively store power generation from renewable sources as well as high-temperature superconducting systems used in generators, transformers and synchronous motors in power stations and heavy-industry facilities. However, to be effective, these systems must be superior to conventional systems and, in reality, market penetration will occur as existing electrical machinery is written off. At current write-off rates, to achieve a 50% transfer to superconducting systems will take 20 years (Hartikainen et al 2003 Supercond. Sci. Technol. 16 963). The Roadmap next considers dc transmission of green power with a section by Eckroad and Marian who provide an update on the development of superconducting power transmission lines in view of recent sustainability studies. The potential of magnetic energy storage is then presented by Coi and Kim, who argue that a successful transition to wind and solar power generation must be harmonized with the conventional electrical network, which requires a storage technology with a fast response and long backup times. Transport. Superconducting Maglev trains and motors for international shipping have the potential to considerably reduce the emissions that contribute to greenhouse gases while improving their economic viability by reducing losses and improving efficiencies. International shipping, alone, contributes 3% of the greenhouse gas emissions. Three sections of the Roadmap identify how high-speed rail can be a major solution to providing fast, low energy, environmentally-friendly transport enabling reduction in automobile and aircraft travel by offering an alternative that is very competitive. With maritime international environmental regulations tightening, HTS motors with the characteristics of high torque and compactness will become important devices for

Quantum suppression of superconductivity in nanowires

International Nuclear Information System (INIS)

Bezryadin, Alexey

2008-01-01

It is of fundamental importance to establish whether there is a limit to how thin a superconducting wire can be, while retaining its superconducting character-and if there is such limit, to understand what determines it. This issue may be of practical importance in defining the limit to miniaturization of superconducting electronic circuits. Recently, a new fabrication method, called molecular templating, was developed and used to answer such questions. In this approach, a suspended carbon nanotube is coated with a thin superconducting metal film, thus forming a superconducting nanowire. The wire obtained is automatically attached to the two leads formed by the sides of the trench. The usual material for such wires is the amorphous alloy of MoGe (Graybeal 1985 PhD Thesis Stanford University; Graybeal and Beasley 1984 Phys. Rev. B 29 4167; Yazdani and Kapitulnik 1995 Phys. Rev. Lett. 74 3037; Turneaure et al 2000 Phys. Rev. Lett. 84 987). Such wires typically exhibit a high degree of homogeneity and can be made very small: as thin as ∼5 nm in diameter and as short as ∼40 nm in length. The results of transport measurements on such homogeneous wires can be summarized as follows. Short wires, shorter than some empirical length, ∼200 nm for MoGe, exhibit a clear dichotomy. They show either a superconducting behavior, with the resistance controlled by thermal fluctuations, or a weakly insulating behavior, with the resistance controlled by the weak Coulomb blockade. Thus a quantum superconductor-insulator transition (SIT) is indicated. Longer wires exhibit a gradual crossover behavior, from almost perfectly superconducting to normal or weakly insulating behavior, as their diameter is reduced. Measurements of wires, which are made inhomogeneous (granular) on purpose, show that such wires, even if they are short in the sense stated above, do not show a clear dichotomy, which could be identified as an SIT (Bollinger et al 2004 Phys. Rev. B 69 180503(R)). Thus

Effect of short-range ordering on the electrical conductivity and superconducting properties of Nb6C5 single crystals

International Nuclear Information System (INIS)

Utkina, T.G.

1995-01-01

Niobium carbide, NbC x , belongs to the family of so called interstital phases. Metal atoms form a face-centered cubic lattice, whose octahedral interstices are occupied by carbon atoms. The fraction (1 - x) of interstices remain vacant, and this determines the nonstoichiometry of these phases: most of them are characterized by a wide homogeneity range, 0.70 m ≅ 3308 - 3886 K). In contrast, the metalloid atoms exhibit high mobility at relatively low temperatures. For compositions close to Nb 6 C 5 (0.81 O-D ≅ 1300 K. The presence of vacancies in the carbon sublattice considerably affects the physical properties of carbides, which depend not only on total vacancy concentration but also on their distribution, i.e., on the degree of ordering (both short-range and long-range order) in the metalloid sublattice. The purpose of this work is to study the effects of such ordering on the superconducting properties of Nb 6 C 5 single crystals

Interactions between superconductivity and quantum criticality in CeCoIn5, URhGe and UCoGe

International Nuclear Information System (INIS)

Howald, L.

2011-01-01

The subject of this thesis is the analyze of the superconducting upper critical field (Hc2) and the interaction between superconductivity and quantum critical points (QCP), for the compounds CeCoIn 5 , URhGe and UCoGe. In CeCoIn 5 , study by mean of resistivity of the Fermi liquid domain allows us to localize precisely the QCP at ambient pressure. This analyze rule out the previously suggested pinning of Hc2(0) at the QCP. In a second part, the evolution of Hc2 under pressure is analyzed. The superconducting dome is unconventional in this compound with two characteristic pressures: at 1.6 GPa, the superconducting transition temperature is maximum but it is at 0.4 GPa that physical properties (maximum of Hc2(0), maximum of the initial slope dHc2/dT, maximum of the specific heat jump DC/C,... ) suggest a QCP. We explain this antagonism with pair-breaking effects in the proximity of the QCP. With these two experiments, we suggest a new phase diagram for CeCoIn 5 . In a third part, measurements of thermal conductivity on URhGe and UCoGe are presented. We obtained the bulk superconducting phase transition and confirmed the unusual curvature of the slope dHc2/dT observed by resistivity. The temperatures and fields dependence of thermal conductivity allow us to identify a non-electronic contribution for heat transport down to the lowest temperature (50 mK) and probably associated with magnon or longitudinal fluctuations. We also identified two different domains in the superconducting region, These domains are compatible with a two bands model for superconductivity. Thermopower measurements on UCoGe reveal a strong anisotropy to current direction and several anomaly under field applied in the b direction. We suggest a Lifshitz transition to explain our observations in these two compounds. (author) [fr

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....

Molybdenum-rhenium superconducting suspended nanostructures

Energy Technology Data Exchange (ETDEWEB)

Aziz, Mohsin; Christopher Hudson, David; Russo, Saverio [Centre for Graphene Science, College of Engineering, Mathematics and Physical Sciences, University of Exeter, Exeter EX4 4QF (United Kingdom)

2014-06-09

Suspended superconducting nanostructures of MoRe 50%/50% by weight are fabricated employing commonly used fabrication steps in micro- and nano-meter scale devices followed by wet-etching with Hydro-fluoric acid of a SiO{sub 2} sacrificial layer. Suspended superconducting channels as narrow as 50 nm and length 3 μm have a critical temperature of ≈6.5 K, which can increase by 0.5 K upon annealing at 400 °C. A detailed study of the dependence of the superconducting critical current and critical temperature upon annealing and in devices with different channel widths reveals that desorption of contaminants is responsible for the improved superconducting properties. These findings pave the way for the development of superconducting electromechanical devices using standard fabrication techniques.

Study on the origin of pressure-induced superconductivity of Cs3C60

International Nuclear Information System (INIS)

Fujiki, S.; Kubozono, Y.; Takabayashi, Y.; Kashino, S.; Kobayashi, M.; Ishii, K.; Suematsu, H.

2001-01-01

Physical properties of bco phase of Cs 3+α C 60 (α=0.0-1.0) and A15 phase of Cs 3 C 60 are studied by X-ray diffraction, ESR, AC susceptibility, resistivity and Raman. The ESR of Cs 300(6) C 60 showed a broad peak of ∼380 G due to conduction electron, while no broad peak was observed in the ESR of bco Cs 3+α C 60 (α≠0.0) and A15 phase. This shows that only bco phase of Cs 3 C 60 is metallic. The AC susceptibility of bco phase of Cs 3.2(3) C 60 and Cs 3.5(1) C 60 showed no superconducting transition above 1.3 K even under high pressure, and the resistivity was 0.52 Ω cm for both samples

Superconductivity in Pb inverse opal

International Nuclear Information System (INIS)

Aliev, Ali E.; Lee, Sergey B.; Zakhidov, Anvar A.; Baughman, Ray H.

2007-01-01

Type-II superconducting behavior was observed in highly periodic three-dimensional lead inverse opal prepared by infiltration of melted Pb in blue (D = 160 nm), green (D = 220 nm) and red (D = 300 nm) opals and followed by the extraction of the SiO 2 spheres by chemical etching. The onset of a broad phase transition (ΔT = 0.3 K) was shifted from T c = 7.196 K for bulk Pb to T c = 7.325 K. The upper critical field H c2 (3150 Oe) measured from high-field hysteresis loops exceeds the critical field for bulk lead (803 Oe) fourfold. Two well resolved peaks observed in the hysteresis loops were ascribed to flux penetration into the cylindrical void space that can be found in inverse opal structure and into the periodic structure of Pb nanoparticles. The red inverse opal shows pronounced oscillations of magnetic moment in the mixed state at low temperatures, T 0.9T c has been observed for all of the samples studied. The magnetic field periodicity of resistivity modulation is in good agreement with the lattice parameter of the inverse opal structure. We attribute the failure to observe pronounced modulation in magneto-resistive measurement to difficulties in the precision orientation of the sample along the magnetic field

Superconductivity in bundles of double-wall carbon nanotubes.

Science.gov (United States)

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

2012-01-01

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

Superconductivity and magnetism in Ir-doped GdFeAsO

International Nuclear Information System (INIS)

Cui, Y.J.; Chen, Y.L.; Cheng, C.H.; Yang, Y.; Jiang, J.; Wang, Y.Z.; Zhang, Y.; Zhao, Y.

2010-01-01

The 5d-transition metal, Ir has successfully been doped at Fe site and induced superconductivity in GdFeAsO at T c = 18.9 K and ∼20 atom%. The Ir-doping shortened the c-axis length and stretched the a-axis one, which led to enhance the coupling between the FeAs- and SmO-layer, and to weaken the bonding between Fe and As atom. Paramagnetism was observed in all of the samples, which was resulted from the magnetic Gd ion as in the F-doped GdFeAsO. An upper critical field of GdFe 0.8 Ir 0.2 AsO was extrapolated to around 24 T, much smaller than that of F-doped GdFeAsO owing to a relatively low T c and small value of dH c2 /dT.

Rare-earth doping of high T/sub c/ superconducting perovskites

International Nuclear Information System (INIS)

Mc Kinnon, W.R.; Tarascon, J.M.; Greene, L.H.; Hull, G.W.

1987-01-01

In most superconductors, the magnetic moments of rare-earth (Re) ions interact with the conduction electrons and break the Cooper pairs, supressing or destroying superconductivity. But in the perovskite-based superconductors discovered recently, the rare-earth ions are separated from the copper and oxygen where the superconducting electrons are believed to be located. The authors study the effects of rare-earth doping in both the 40K La/sub 2-x/Sr/sub x/CuO/sub 4-y/ system and 90K YBa/sub 2/Cu/sub 3/O/sub 7-x/ system. In these materials, the RE ions only weakly affect superconductivity, and the effects we do see are more strongly correlated with changes in the volume of the crystal than with the magnetism of the rare earths

Interface-Induced Zeeman-Protected Superconductivity in Ultrathin Crystalline Lead Films

Directory of Open Access Journals (Sweden)

Yi Liu

2018-04-01

Full Text Available Two-dimensional (2D superconducting systems are of great importance for exploring exotic quantum physics. The recent development of fabrication techniques has stimulated studies of high-quality single-crystalline 2D superconductors, where intrinsic properties give rise to unprecedented physical phenomena. Here, we report the observation of Zeeman-type spin-orbit interaction protected superconductivity (Zeeman-protected superconductivity in 4-monolayer (ML to 6-ML crystalline Pb films grown on striped incommensurate Pb layers on Si(111 substrates by molecular beam epitaxy. An anomalously large in-plane critical field far beyond the Pauli limit is detected, which can be attributed to the Zeeman-protected superconductivity due to the in-plane inversion symmetry breaking at the interface. Our work demonstrates that, in superconducting heterostructures, the interface can induce Zeeman-type spin-orbit interactions and modulate the superconductivity.

High temperature interface superconductivity

International Nuclear Information System (INIS)

Gozar, A.; Bozovic, I.

2016-01-01

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

Coupling between magnetic and superconducting order parameters and evidence for the spin excitation gap in the superconducting state of a heavy fermion superconductor UPd2Al3

International Nuclear Information System (INIS)

Metoki, Naoto; Haga, Yoshinori; Koike, Yoshihiro; Aso, Naofumi; Onuki, Yoshichika

1997-01-01

Neutron scattering experiments have been carried out in order to study the interplay between magnetism and superconductivity in a heavy fermion superconductor, UPd 2 Al 3 . We have observed 1% suppression of the (0 0 0.5) magnetic peak intensity below the superconducting transition temperature T c . This is direct evidence for the coupling of the magnetic order parameter with the superconducting one. Furthermore, we have observed a spin excitation gap associated with superconductivity. The gap energy ΔE g increases continuously from ΔE g =0 to 0.4 meV with decreasing temperature from T c to 0.4 K. This gap energy corresponds to 2k B T c , which is smaller than the superconducting gap expected from the BCS theory (3.5k B T c ). These results are indicative of the strong interplay between magnetism and superconductivity. (author)

Structure, resistivity, critical field, specific-heat jump at Tc, Meissner effect, a.c. and d.c. Susceptibility of the high-temperature superconductor La2-xSrxCuO4

International Nuclear Information System (INIS)

Decroux, M.; Junod, A.; Bezinge, A.

1987-01-01

The temperature dependence of the resistivity, the magnetic properties and the specific heat were investigated on sintered samples of La 1.85 Sr 0.15 CuO 4 having zero resistance below 35 K. The crystal structure at 300K (tetragonal K 2 NiF 4 -type) was refined from X-ray powder diffraction data. The d.c. susceptibility shows no indication for the existence of localized Cu 2+ moments. The observation of a 60% Meissner effect and a smeared jump at T c in the specific-heat curve prove the intrinsic character of this superconducting state. The amplitude of this jump is compatible with the DOS estimated from the Pauli susceptibility. With a critical magnetic field slope dH c2 /dT| Tc = - 2.5 T/K, the orbital critical field is expected to be of the order of 64 T

Hydrostatic Pressure Study on 3-K Phase Superconductivity in Sr2RuO4-Ru Eutectic Crystals by AC Magnetic Susceptibility Measurements

International Nuclear Information System (INIS)

Yaguchi, Hiroshi; Watanabe, Hiromichi; Sakaue, Akira

2012-01-01

We have investigated the effect of hydrostatic pressure on 3-K phase superconductivity in Sr 2 RuO 4 -Ru eutectic crystals by means of AC magnetic susceptibility measurements. We have found that the application of hydrostatic pressure suppresses the superconducting transition temperature T c of the 3-K phase with a pressure coefficient of dT c /dP ≈ −0.2 K/GPa, similar to the case of the 1.5-K phase. We have also observed that the effect of hydrostatic pressure on the 3-K phase seems to be elastic whilst that of uniaxial pressure is plastic.

Measuring the microwave response of superconducting Nb:STO and Ti at mK temperatures using superconducting resonators

Energy Technology Data Exchange (ETDEWEB)

Thiemann, Markus; Beutel, Manfred; Dressel, Martin; Scheffler, Marc [1. Physikalisches Institut, Universitaet Stuttgart (Germany); Fillis-Tsirakis, Evangelos; Boschker, Hans; Mannhart, Jochen [Max Planck Institute for Solid State Research, Stuttgart (Germany)

2016-07-01

Niobium doped SrTiO{sub 3} is a superconductor, with the lowest charge carrier density among all superconductors. It shows a dome in the transition temperature as a function of doping concentration with a maximum T{sub c} ∼ 0.3 K. The superconducting dome may originate from the different bands being occupied depending on the doping level. The low energy scales of the system, as indicated by the low T{sub c} are within the GHz-regime. Therefore microwave measurements are a powerful technique to reveal the electronic properties of these superconductors. We preformed microwave measurements on Nb:STO of different doping levels in a dilution refrigerator, using superconducting stripline resonators. Measurements were done in a temperature and frequency range from 40-400 mK and 1-20 GHz, covering the normal and superconducting states. For comparison we also measured the temperature dependence of the surface impedance of superconducting titanium (T{sub c} ∼ 0.5 K), which can be well described by the Mattis-Bardeen equations with a ratio (2Δ)/(k{sub B}T{sub c}) = 3.56. Therefore titanium is an ideal reference sample representing a conventional BCS-superconductor.

Superconductivity

International Nuclear Information System (INIS)

Palmieri, V.

1990-01-01

This paper reports on superconductivity the absence of electrical resistance has always fascinated the mind of researchers with a promise of applications unachievable by conventional technologies. Since its discovery superconductivity has been posing many questions and challenges to solid state physics, quantum mechanics, chemistry and material science. Simulations arrived to superconductivity from particle physics, astrophysic, electronics, electrical engineering and so on. In seventy-five years the original promises of superconductivity were going to become reality: a microscopical theory gave to superconductivity the cloth of the science and the level of technological advances was getting higher and higher. High field superconducting magnets became commercially available, superconducting electronic devices were invented, high field accelerating gradients were obtained in superconductive cavities and superconducting particle detectors were under study. Other improvements came in a quiet progression when a tornado brought a revolution in the field: new materials had been discovered and superconductivity, from being a phenomenon relegated to the liquid Helium temperatures, became achievable over the liquid Nitrogen temperature. All the physics and the technological implications under superconductivity have to be considered ab initio

Superconducting linac booster

International Nuclear Information System (INIS)

Srinivasan, B.; Betigeri, M.G.; Pandey, M.K.; Pillay, R.G.; Kurup, M.B.

1997-01-01

The report on superconducting LINAC booster, which is a joint project of Bhabha Atomic Research Centre (BARC) and Tata Institute of Fundamental Research (TIFR), brings out the work accomplished so far towards the development of the technology of superconducting LINAC to boost the energy of ions from the 14UD Pelletron. The LINAC is modular in construction with each module comprising of a helium cryostat housing four lead-plated quarter wave resonators. The resonators are superconducting for temperatures below 7.19K. An energy boost of 2 MeV/q per module is expected to be achieved. The first module and the post-tandem superbuncher have been fabricated and tested on the LINAC beam line. This report gives a summary of the technological achievements and also brings out the difficulties encountered during the R and D phase. (author)

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

Superconducting joint of Bi-2223/Ag superconducting tapes by diffusion bonding

International Nuclear Information System (INIS)

Guo Wei; Zou Guisheng; Wu Aiping; Wang Yanjun; Bai Hailin; Ren Jialie

2009-01-01

61-Filaments Bi-2223/Ag superconducting tapes have been joined by diffusion bonding. The critical currents (I C s) of the joints are obtained by using standard four probe method under no magnetic field in the liquid nitrogen. The microstructures of the joints are evaluated by the electron microscope in electron backscatter diffraction mode and the phase compositions of the superconducting cores of the joint and the original tape are determined by X-ray diffraction (XRD). The results show diffusion bonding is effective bonding technique for HTS tapes, and the bonding time is reduced greatly from hundreds of hours to a few hours, and the bonding pressure also changes from 140-4000 MPa to 3 MPa. Furthermore, the diffusion bonding joints sustain superconducting properties, and the critical current ratios (CCR O ) of the joints are in the range of 35%-80%. Microstructures of the typical joint display a good bonding and some defects existed in traditional method are avoided. XRD results show that the phase compositions of the superconducting cores have no obvious changes before and after diffusion bonding, which offers physical and material bases for high superconducting property of the joints.

Anisotropic superconductivity in {beta}-(BDA-TTP){sub 2}SbF{sub 6}: STM spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Nomura, K. [Department of Physics, Hokkaido University, Sapporo 060-0810 (Japan)], E-mail: knmr@phys.sci.hokudai.ac.jp; Muraoka, R.; Matsunaga, N. [Department of Physics, Hokkaido University, Sapporo 060-0810 (Japan); Ichimura, K. [Division of Applied Physics, Hokkaido University, Sapporo 060-8628 (Japan); Yamada, J. [Division of Material Science, University of Hyogo, Hyogo 678-1297 (Japan)

2009-03-01

We have investigated the gap symmetry in the superconducting phase of {beta}-(BDA-TTP){sub 2}SbF{sub 6} with use of the scanning tunneling microscope (STM). The tunneling spectra obtained on the conducting surface show a clear superconducting gap structure. Its functional form is of V-shaped similarly to {kappa}-(BEDT-TTF){sub 2}X and suggests the anisotropic superconducting gap with line nodes. For lateral surfaces the shape of tunneling spectra varies from the U-shape with relatively large gap to the V-shape with small gap depending on the tunneling direction alternately twice between directional angle 0 and {pi}. From the analysis of conductance curve taking the k dependence of the tunneling probability into account, it is found that the gap has maximum near the a* and c* axes and the nodes appear along near a*+c* and the a-c* directions. These indicate that the d{sub x{sup 2}-y{sup 2}} like superconducting pair is formed in this system as the case of {kappa}-(BEDT-TTF){sub 2}X. This node direction is consistent with the theoretical prediction based on the spin fluctuation mechanism. However, the zero-bias conductance peak has not been observed yet.

Conceptual design of a 2 tesla superconducting solenoid for the Fermilab D{O} detector upgrade

Energy Technology Data Exchange (ETDEWEB)

Brzezniak, J.; Fast, R.W.; Krempetz, K.

1994-05-01

This paper presents a conceptual design of a superconducting solenoid to be part of a proposed upgrade for the D0 detector. This detector was completed in 1992, and has been taking data since then. The Fermilab Tevatron had scheduled a series of luminosity enhancements prior to the startup of this detector. In response to this accelerator upgrade, efforts have been underway to design upgrades for D0 to take advantage of the new luminosity, and improvements in detector technology. This magnet is conceived as part of the new central tracking system for D0, providing a radiation-hard high-precision magnetic tracking system with excellent electron identification.

Tailoring Superconductivity with Quantum Dislocations.

Science.gov (United States)

Li, Mingda; Song, Qichen; Liu, Te-Huan; Meroueh, Laureen; Mahan, Gerald D; Dresselhaus, Mildred S; Chen, Gang

2017-08-09

Despite the established knowledge that crystal dislocations can affect a material's superconducting properties, the exact mechanism of the electron-dislocation interaction in a dislocated superconductor has long been missing. Being a type of defect, dislocations are expected to decrease a material's superconducting transition temperature (T c ) by breaking the coherence. Yet experimentally, even in isotropic type I superconductors, dislocations can either decrease, increase, or have little influence on T c . These experimental findings have yet to be understood. Although the anisotropic pairing in dirty superconductors has explained impurity-induced T c reduction, no quantitative agreement has been reached in the case a dislocation given its complexity. In this study, by generalizing the one-dimensional quantized dislocation field to three dimensions, we reveal that there are indeed two distinct types of electron-dislocation interactions. Besides the usual electron-dislocation potential scattering, there is another interaction driving an effective attraction between electrons that is caused by dislons, which are quantized modes of a dislocation. The role of dislocations to superconductivity is thus clarified as the competition between the classical and quantum effects, showing excellent agreement with existing experimental data. In particular, the existence of both classical and quantum effects provides a plausible explanation for the illusive origin of dislocation-induced superconductivity in semiconducting PbS/PbTe superlattice nanostructures. A quantitative criterion has been derived, in which a dislocated superconductor with low elastic moduli and small electron effective mass and in a confined environment is inclined to enhance T c . This provides a new pathway for engineering a material's superconducting properties by using dislocations as an additional degree of freedom.

Note from the radioprotection group's shipping service

CERN Multimedia

2006-01-01

Le service SHIPPING du groupe de radioprotection souhaite vous rappeler qu'avant toute expédition de matériel susceptible d'être radioactif, une demande de transport doit être établie par EDH en cochant la case appropriée (danger radioactif). Merci de bien vouloir prendre note des informations figurant dans le site Web: http://cern.ch/service-rp-shipping Toute demande non conforme ne sera pas prise en compte. Radioactive Shipping Service http://cern.ch/service-rp-shippingTél: 73171Fax: 69200

JFMCC: Theater C2 in Need of SOLE

Science.gov (United States)

2003-02-03

four command ships in service presently in the Navy. “Of the four command ships in service today, two—the Mount Whitney (LCC-20) and the Blue Ridge ...Dr. Henry H. Gaffney , Jr., The Top 100 Rules of the New American Way of War, (Washington, D.C.: Office of Force Transformation, Office of the...2001. Barnett, Thomas and Gaffney , Henry H. The Top 100 Rules of the New American Way of War. Washington, D.C.: Office of

Analysis of transmittance properties in 1D hybrid dielectric photonic crystal containing superconducting thin films

Science.gov (United States)

Soltani, Osswa; Zaghdoudi, Jihene; Kanzari, Mounir

2018-06-01

By means of two fluid model and transfer matrix method (TMM), we investigate theoretically the transmittance properties of a defective hybrid dielectric-dielectric photonic crystal that contains a superconducting material as a defect layer. The considered hybrid photonic structure is: H(LH) 7(HLSLH) P H(LH) 7 , where H is the high refractive index dielectric, L is the low refractive index dielectric, S is the superconducting material and P is the repetitive number. The results show that the variation of the number and the positions of the transmissions modes depend strongly on the repetitive number P, the temperature T and the thickness of the layer S. An improvement of the spectral response is obtained with the exponential gradation of layer thicknesses dj =d0 + βejα , where d0 is the initial thickness of the layer j, α and β are two particular constants for each material. In addition, the effect of the incident angle for both transverse electric (TE) and transverse magnetic (TM) polarizations on the transmittance spectrum is discussed. As a result, we propose a tunable narrow stop-band polychromatic filter that covers the visible wavelength.

On the proximity effect in a superconductive slab bordered by metal

International Nuclear Information System (INIS)

Liniger, W.

1993-01-01

The first Ginzburg-Landau equation for the order parameter ψ in the absence of magnetic fields is solved analytically for a superconducting slab of thickness 2d boardered by semi-infinite regions of normal metal at each face. The real-valued normalized wave function f=ψ/ψ ∞ depends only on the transversal spatial coordinate x, normalized with respect to the coherence length ξ of the superconductor, provided the de Gennes boundary condition df/dx=f/b is used. The closed-form solution expresses x as an elliptic integral of f, depending on the normalized parameters d and b. It is predicted theoretically that, for b c =arctan(1/b), the proximity effect is so strong that the superconductivity is completely suppressed. In fact, in this case, the first Ginzburg-Landau equation possesses only the trivial solution f≡0

Superconducting properties and microstructure of YBa2Cu3O7-δ/PrBa2Cu3O7-δ superlattices

International Nuclear Information System (INIS)

Lowndes, D.H.; Norton, D.P.; Zheng, X.Y.; Zhu, Shen

1991-10-01

Epitaxial YBa 2 Cu 3 O 7-δ /PrBa 2 Cu 3 O 7-δ (YBCO/PBCO) superlattices are tools for systematic, fundamental studies of high-temperature superconductivity. The variation of T c in YBCO/PBCO superlattices can be understood as arising from changes in the interlayer phase coupling between YBCO layers that are highly two-dimensional when they are very thin (∼1--2 c-axis unit cells) and completely isolated from each other. Single-cell-thick YBCO layers, containing isolated pairs of CuO 2 planes, are found to be superconducting at T c ∼ 20 K, in a PBCO matrix. The resistance in the superconducting transition region scales with temperature as expected for the (flux flow) resistance produced by thermally generated 2D vortices, or for a 2D array of superconducting weak links. Relative to both thin-film and single-crystal HTSc specimens, the thin superconducting layers in YBCO/PBCO superlattices exhibit a greatly expanded temperature range over which characteristic 2D dissipation can be observed, as a consequence of the enhanced anisotropy and reduced dimensionality of the YBCO layers. Scanning tunneling microscope studies reveal that YBCO films and YBCO/PBCO superlattices grow unit cell-by-unit cell by a terraced-island growth mechanism. On miscut, near-(001) substrates the terraces are epitaxially aligned with the substrate crystal lattice and spiral growth structures (screw dislocation-mediated growth) are not seen. These observations explain the steps or ''kinks'' that are seen in cross-section Z-contrast TEM images of YBCO/PBCO superlattices. The kinks may correspond physically to regions where the supercurrent must tunnel along the c- axis, and thus may be weak-link barriers. 31 refs., 7 figs

Dirac-fermions in graphene d-wave superconducting heterojunction with the spin orbit interaction

Science.gov (United States)

Wang, Juntao; Wang, Andong; Zhang, Rui; Sun, Deng; Yang, Yanling

2017-09-01

In this study, based on the Dirac-Bogoliubov-de Gennes equation, we theoretically investigate the interaction effect between the anisotropic d-wave pairing symmetry and the spin orbit interaction (the Rashba spin orbit interaction (RSOI) and the Dresselhaus spin orbit interaction (DSOI)) in a graphene superconducting heterojunction. We find that the spin orbit interaction (SOI) plays a critical role on the tunneling conductance in the pristine case, but minimally affecting the tunneling conductance in the heavily doped case. As for the zero bias state, in contrast to the keep intact feature in the heavily doped case, it exhibits a distinct dependence on the RSOI and the DSOI in the pristine case. In particular, the damage of the zero bias state with a slight DSOI results in the disappearance of the zero bias conductance peak. Moreover, the tunneling conductances also show a qualitative difference with respect to the RSOI when both the RSOI and the DSOI are finite. These remarkable results suggest that the SOI and the anisotropic superconducting gap can be regarded as a key tool for diagnosing the specular Andreev reflection.

Feshbach shape resonance for high Tc superconductivity in superlattices of nanotubes

International Nuclear Information System (INIS)

Bianconi, Antonio

2006-01-01

The case of a Feshbach shape resonance in the pairing mechanism for high T c superconductivity in a crystalline lattice of doped metallic nanotubes is described. The superlattice of doped metallic nanotubes provides a superconductor with a strongly asymmetric gap. The disparity and different spatial locations of the wave functions of electrons in different subbands at the Fermi level should suppress the single electron impurity interband scattering giving multiband superconductivity in the clean limit. The Feshbach resonances will arise from the component single-particle wave functions out of which the electron pair wave function is constructed: pairs of wave functions which are time inverse of each other. The Feshbach shape resonance increases the critical temperature by tuning the chemical potential at the Lifshitz electronic topological transition (ETT) where the Fermi surface of one of the bands changes from the one dimensional (1D) to the two dimensional (2D) topology (1D/2D ETT). (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (Abstract Copyright [2006], Wiley Periodicals, Inc.)

The pseudogap in the c-axis optical conductivity in high Tc-cuprates

International Nuclear Information System (INIS)

Won, H.

1999-01-01

The pseudogap phenomenon is most remarkable in the underdoped region of high-T c cuprates. Since the superconducting state in the optimally doped high-T c cuprates is well described by the BCS-like d-wave superconductors, it is natural to assume that the pseudogap arises from the standard superconducting fluctuation. In particular in the layered compounds like high-T c cuprates Varlamov and his coworkers pointed out the density of states (DOS) correction to the superconducting fluctuation will play the crucial role. However, unfortunately in their analysis d-wave nature of the high-T c cuprates is ignored. Perhaps more seriously some unnecessary approximations were introduced in their analysis. The present theory gives somewhat different expressions of quasi-particle density of states for B = 0 and B ≠ 0, which can be tested experimentally. (orig.)

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...

Introduction to superconductivity and high-Tc materials

International Nuclear Information System (INIS)

Cyrot, M.; Pavuna, D.

1991-01-01

What sets this book apart from other introductions to superconductivity and high-T c materials is its pragmatic approach. In this book the authors describe all relevant superconducting phenomena and rely on the macroscopic Ginzburg-Landau theory to derive the most important results. Examples are chosen from selected conventional superconductors like NbTi and compared to those high-T c materials. The text should be of interest to non-specialists in superconductivity either as a textbook for those entering the field (one semester course) or as researchers in advanced technologies and even some managers of interdisciplinary research projects

Superconductivity and magnetism in Ir-doped GdFeAsO

Energy Technology Data Exchange (ETDEWEB)

Cui, Y.J.; Chen, Y.L. [Key Laboratory of Magnetic Levitation and Maglev Trains (Ministry of Education of China), Superconductivity R and D Center (SRDC), Mail Stop 165, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China); Cheng, C.H. [School of Materials Science and Engineering, University of New South Wales, Sydney 2052 NSW (Australia); Yang, Y.; Jiang, J.; Wang, Y.Z.; Zhang, Y. [Key Laboratory of Magnetic Levitation and Maglev Trains (Ministry of Education of China), Superconductivity R and D Center (SRDC), Mail Stop 165, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China); Zhao, Y., E-mail: yzhao@swjtu.edu.c [Key Laboratory of Magnetic Levitation and Maglev Trains (Ministry of Education of China), Superconductivity R and D Center (SRDC), Mail Stop 165, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China); School of Materials Science and Engineering, University of New South Wales, Sydney 2052 NSW (Australia)

2010-11-01

The 5d-transition metal, Ir has successfully been doped at Fe site and induced superconductivity in GdFeAsO at T{sub c} = 18.9 K and {approx}20 atom%. The Ir-doping shortened the c-axis length and stretched the a-axis one, which led to enhance the coupling between the FeAs- and SmO-layer, and to weaken the bonding between Fe and As atom. Paramagnetism was observed in all of the samples, which was resulted from the magnetic Gd ion as in the F-doped GdFeAsO. An upper critical field of GdFe{sub 0.8}Ir{sub 0.2}AsO was extrapolated to around 24 T, much smaller than that of F-doped GdFeAsO owing to a relatively low T{sub c} and small value of dH{sub c2}/dT.

Neutron diffraction studies of magnetic ordering in superconducting ErNi2B2C and TmNi2B2C in an applied magnetic field

DEFF Research Database (Denmark)

Toft, Katrine Nørgaard

The field-induced magnetic structures of ErNi2B2C and TmNi2B2C in are especially interesting because the field suppresses the superconducting order parameter and therefore the magnetic properties can be studied while varying the strength ofsuperconductivity. ErNi2B2C: For magnetic fields along all.......483,0,0). The appearance of the QN phase wasinitially believed to be caused by the suppression of superconductivity. This suppression should make it favorable to create a magnetic order with a Q-vector determined by the maximum in the magnetic susceptibility at the Fermi surface nesting vector QN.The phase diagram...... three symmetry directions, the observed magnetic structures have a period corresponding to the Fermi surface nesting structure. The phase diagrams present all the observed magnetic structures.Two results remain unresolved: 1. When applying the magnetic field along [010], the minority domain (QNB = (0,Q...

Melt formed superconducting joint between superconducting tapes

International Nuclear Information System (INIS)

Benz, M.G.; Knudsen, B.A.; Rumaner, L.E.; Zaabala, R.J.

1992-01-01

This patent describes a superconducting joint between contiguous superconducting tapes having an inner laminate comprised of a parent-metal layer selected from the group niobium, tantalum, technetium, and vanadium, a superconductive intermetallic compound layer on the parent-metal layer, a reactive-metal layer that is capable of combining with the parent-metal and forming the superconductive intermetallic compound, the joint comprising: a continuous precipitate of the superconductive intermetallic compound fused to the tapes forming a continuous superconducting path between the tapes

Green Shipping Practices of Shipping Firms

Directory of Open Access Journals (Sweden)

Young-Tae Chang

2017-05-01

Full Text Available The primary objective of this study is to provide an empirical research using structural equation modeling to identify the factors that motivate shipping firms to adopt green shipping practices (GSP. Furthermore, it also examines if adopting GSP can enhance the shipping firms’ environmental and productivity performance. The findings show that shipping firms are motivated to adopt GSP mostly by industrial norms set by institutionalized associations. They are also motivated by customers’ demand for environmental friendliness and their own strategy to make good image. Unlike our expectation, government regulations and international environmental laws are not significant in influencing shipping firms to adopt GSP. Moreover, adoption of green shipping practices can improve the environmental and productivity performance of the shipping firms.

Superconducting transition and low-field magnetoresistance of a niobium single crystal at 4.2 deg. K; Transition supraconductrice et magnetoresistance en champ faible d'un echantillon monocristallin de niobium a 4.2 deg. K

Energy Technology Data Exchange (ETDEWEB)

Perriot, G [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires. Service de physique du solide et de resonnance magnetique

1967-01-01

We report the study of the electrical resistance of a niobium single crystal, at 4.2 deg. K, from the beginning of the superconductive transition to 80 kilo oersteds. Critical fieldsH{sub c2} and H{sub c3} have been determined. Influences on superconductive transition of current density, field-current angle, crystal orientation and magnetoresistance have been studied. Variation laws of low-field transverse and longitudinal magneto-resistances have been determined. (author) [French] La variation de la resistance electrique d'un monocristal cylindrique de niobium a ete etudiee, a 4,2 deg. K, depuis le debut de la transition supraconductrice jusqu'a 80 kilooersteds. Les champs critiques H{sub c2} et H{sub c3} ont ete determines. On a etudie l'influence de la densite de courant, de l'angle champ-courant, de l'anisotropie cristalline et de la magnetoresistance sur la transition supraconductrice. Les lois de variation des magnetoresistances transversale et longitudinale ont ete determinees dans le domaine des champs faibles. (auteur)

Hydrostatic pressure dependence of the superconducting transition temperature of HgBa2CaCu2O6+δ and HgBa2Ca2Cu3O8+δ

International Nuclear Information System (INIS)

Klehe, A.K.; Schilling, J.S.

1994-02-01

The dependence of the superconducting transition temperature T c (P) on purely hydrostatic pressure to 0.9 GPa has been determined in ac susceptibility studies in a He-gas pressure system for optimally doped ceramic samples of HgBa 2 CaCu 2 O 6+δ and HgBa 2 Ca 2 Cu 3 O 8+δ with superconducting transitions at T c (0) ≅ 126.6 K and 133.9 K, respectively. T c increases reversibly under hydrostatic pressure at the rates, d T c /dP ≅ +1.80 ± 0.06 K/GPa and +1.71 ± 0.05 K/GPa, respectively. Within experimental error, these values are the same as found previously for optimally doped single-layered HgBa 2 CuO 4+δ , where d T c /dP ≅ +1.72 ± 0.05 K/GPa. Remarkably, the logarithmic volume derivative of T c is nearly identical for all three compounds, dln T c /dlnV ≅ -1.20 ± 0.05, even though the bulk modulus differs by more than 30%. This provides strong evidence that a common mechanism is responsible for the pressure dependence of the superconducting state in all three compounds

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

On the localisation of charge carriers and suppression of superconductivity by praseodymium in systems derived from YBa2Cu3O7-d

International Nuclear Information System (INIS)

Infante, C.; El Mously, M.K.; Dayal, R.; Husain, M.; Siddiqi, S.A.; Ganguly, P.

1990-04-01

The effect of Pr substitution in suppressing T c in LaCaBaCu 3 O 7-d and Y 0.8 Ca 0.2 Ba 2 Cu 3 O 6+d has been studied. Infra-red spectroscopy and a model based on ionic radii considerations were used to examine the location of Pr ions and the influence of Pr and Ca ions on hole localisation on chains and planes. For this purpose the series PrBa 2-x Ca x Cu 3 O 7-d was also studied. The main conclusions are that Pr ions play a role in suppressing T c by exchange scattering and to some extent by the hole filling mechanism involving the formation of Pr 4+ . The Pr ions in La 1-x Pr x CaBaCu 3 O 7-d exist in both the Y and Ba sites. The magnitude of the resistivity at the insulator-metal transition for the polycrystalline samples is consistent with an anisotropic superconductor in which superconductivity accompanies metallization. The rate of suppression of T c is similar as in Y 1-x Pr x Ba 2 Cu 3 O 7d but it is suggested that a percolation model may explain the results more adequately than the Abrikosov-Gorkov theory. (author). 48 refs, 10 figs, 1 tab

Spin-fluctuation mechanism of high-Tc superconductivity and order-parameter symmetry

International Nuclear Information System (INIS)

Izyumov, Yurii A

1999-01-01

The notion that electrons in high-T c cuprates pair via antiferromagnetic spin fluctuations is discussed and the symmetry of the superconducting order parameter is analyzed. Three approaches to the problem, one phenomenological (with an experimental dynamic magnetic susceptibility) and two microscopic (involving, respectively, the Hubbard model and the tJ-model) are considered and it is shown that in each case strong-coupling theory leads to a d-wave order parameter with zeros at the Fermi surface. The review then proceeds to consider experimental techniques in which the d-symmetry of the order parameter may manifest itself. These include low-temperature thermodynamic measurements, measurements of the penetration depth and the upper critical field, Josephson junction experiments to obtain the phase of the superconducting order parameter, and various spectroscopic methods. The experimental data suggest that the order parameter in cuprates is d x 2 -y 2 -wave. Ginzburg-Landau theory for a superconductor with a d-wave order parameter is outlined and both an isolated vortex and a vortex lattice are investigated. Finally, some theoretical aspects of the effects of nonmagnetic impurities on a d-wave superconductor are considered. (reviews of topical problems)

Higgsless superconductivity from topological defects in compact BF terms

Directory of Open Access Journals (Sweden)

M. Cristina Diamantini

2015-02-01

Full Text Available We present a new Higgsless model of superconductivity, inspired from anyon superconductivity but P- and T-invariant and generalisable 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 low-energy effective BF theories. In the average field approximation, the corresponding uniform emergent charge creates a gap for the (D−2-dimensional branes via the Magnus force, the dual of the Lorentz force. One particular combination of intrinsic and emergent charge fluctuations that leaves the total charge distribution invariant constitutes an isolated gapless mode leading to superfluidity. The remaining massive modes organise themselves into a D-dimensional charged, massive vector. 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 this type of superconductivity is explicitly realised as global superconductivity in Josephson junction arrays. In 3D this model predicts a possible phase transition from topological insulators to Higgsless superconductors.

Weak antilocalization effect and noncentrosymmetric superconductivity in a topologically nontrivial semimetal LuPdBi

KAUST Repository

Xu, Guizhou; Wang, Wenhong; Zhang, Xiaoming; Du, Yin; Liu, Enke; Wang, Shouguo; Wu, Guangheng; Liu, Zhongyuan; Zhang, Xixiang

2014-01-01

A large number of half-Heusler compounds have been recently proposed as three-dimensional (3D) topological insulators (TIs) with tunable physical properties. However, no transport measurements associated with the topological surface states have been observed in these half-Heusler candidates due to the dominating contribution from bulk electrical conductance. Here we show that, by reducing the mobility of bulk carriers, a two-dimensional (2D) weak antilocalization (WAL) effect, one of the hallmarks of topological surface states, was experimentally revealed from the tilted magnetic field dependence of magnetoconductance in a topologically nontrivial semimetal LuPdBi. Besides the observation of a 2D WAL effect, a superconducting transition was revealed at T c ∼ 1.7â.K in the same bulk LuPdBi. Quantitative analysis within the framework of a generalized BCS theory leads to the conclusion that the noncentrosymmetric superconductivity of LuPdBi is fully gapped with a possibly unconventional pairing character. The co-existence of superconductivity and the transport signature of topological surface states in the same bulk alloy suggests that LuPdBi represents a very promising candidate as a topological superconductor.

Weak antilocalization effect and noncentrosymmetric superconductivity in a topologically nontrivial semimetal LuPdBi

KAUST Repository

Xu, Guizhou

2014-07-21

A large number of half-Heusler compounds have been recently proposed as three-dimensional (3D) topological insulators (TIs) with tunable physical properties. However, no transport measurements associated with the topological surface states have been observed in these half-Heusler candidates due to the dominating contribution from bulk electrical conductance. Here we show that, by reducing the mobility of bulk carriers, a two-dimensional (2D) weak antilocalization (WAL) effect, one of the hallmarks of topological surface states, was experimentally revealed from the tilted magnetic field dependence of magnetoconductance in a topologically nontrivial semimetal LuPdBi. Besides the observation of a 2D WAL effect, a superconducting transition was revealed at T c ∼ 1.7â.K in the same bulk LuPdBi. Quantitative analysis within the framework of a generalized BCS theory leads to the conclusion that the noncentrosymmetric superconductivity of LuPdBi is fully gapped with a possibly unconventional pairing character. The co-existence of superconductivity and the transport signature of topological surface states in the same bulk alloy suggests that LuPdBi represents a very promising candidate as a topological superconductor.

Anomalous He-gas high-pressure studies on superconducting LaO1-xFxFeAs

International Nuclear Information System (INIS)

Bi, W; Banks, H B; Schilling, J S; Takahashi, H; Okada, H; Kamihara, Y; Hirano, M; Hosono, H

2010-01-01

Ac susceptibility measurements have been carried out on superconducting LaO 1-x F x FeAs for x=0.07 and 0.14 under He-gas pressures to ∼0.8 GPa. Not only do the measured values of dT c /dP differ substantially from those obtained in previous studies using other pressure media, but also the T c (P) dependences observed depend on the detailed pressure/temperature history of the sample. A sizeable sensitivity of T c (P) to shear stresses provides a possible explanation.

Magnetic Field Enhanced Superconductivity in Epitaxial Thin Film WTe2.

Science.gov (United States)

Asaba, Tomoya; Wang, Yongjie; Li, Gang; Xiang, Ziji; Tinsman, Colin; Chen, Lu; Zhou, Shangnan; Zhao, Songrui; Laleyan, David; Li, Yi; Mi, Zetian; Li, Lu

2018-04-25

In conventional superconductors an external magnetic field generally suppresses superconductivity. This results from a simple thermodynamic competition of the superconducting and magnetic free energies. In this study, we report the unconventional features in the superconducting epitaxial thin film tungsten telluride (WTe 2 ). Measuring the electrical transport properties of Molecular Beam Epitaxy (MBE) grown WTe 2 thin films with a high precision rotation stage, we map the upper critical field H c2 at different temperatures T. We observe the superconducting transition temperature T c is enhanced by in-plane magnetic fields. The upper critical field H c2 is observed to establish an unconventional non-monotonic dependence on temperature. We suggest that this unconventional feature is due to the lifting of inversion symmetry, which leads to the enhancement of H c2 in Ising superconductors.

Fluctuation conductivity of thin superconductive vanadium films

International Nuclear Information System (INIS)

Dmitrenko, I.M.; Sidorenko, A.S.; Fogel, N.Y.

1982-01-01

Resistive transitions into the superconductive state are studied in thin [d >T/sub c/ the experimental data on the excess conductivity of the films agree qualitatively and quantitively with Aslamazov--Larkin theory. There is no Maki--Thompson contribution to fluctuation conductivity. Near T/sub c/ the excess conductivity sigma' changes exponentially with temperature in accordance with the predictions of the theory of the critical fluctuations of the order parameter. The values of the effective charge carrier mass defined from data on sigma' for the low fluctuation and critical fluctuation regions differ markedly. This difference is within the spread of effective masses for various charge carrier groups already known for vanadium. Causes of the difference in resistive behavior for the regions T >T/sub c/ are considered

Magnetic shielding of an inhomogeneous magnetic field source by a bulk superconducting tube

International Nuclear Information System (INIS)

Hogan, K; Fagnard, J-F; Wéra, L; Vanderheyden, B; Vanderbemden, P

2015-01-01

Bulk type-II irreversible superconductors can act as excellent passive magnetic shields, with a strong attenuation of low frequency magnetic fields. Up to now, the performances of superconducting magnetic shields have mainly been studied in a homogenous magnetic field, considering only immunity problems, i.e. when the field is applied outside the tube and the inner field should ideally be zero. In this paper, we aim to investigate experimentally and numerically the magnetic response of a high-T c bulk superconducting hollow cylinder at 77 K in an emission problem, i.e. when subjected to the non-uniform magnetic field generated by a source coil placed inside the tube. A bespoke 3D mapping system coupled with a three-axis Hall probe is used to measure the magnetic flux density distribution outside the superconducting magnetic shield. A finite element model is developed to understand how the magnetic field penetrates into the superconductor and how the induced superconducting shielding currents flow inside the shield in the case where the emitting coil is placed coaxially inside the tube. The finite element modelling is found to be in excellent agreement with the experimental data. Results show that a concentration of the magnetic flux lines occurs between the emitting coil and the superconducting screen. This effect is observed both with the modelling and the experiment. In the case of a long tube, we show that the main features of the field penetration in the superconducting walls can be reproduced with a simple analytical 1D model. This model is used to estimate the maximum flux density of the emitting coil that can be shielded by the superconductor. (paper)

Accelerator Magnet R&D in the Perspective of a LHeC and HE-LHC - Synergy or Competion?

CERN Document Server

Bottura, L; Bajko, M; Ballarino, A; Borgnolutti, F; Ferracin, P; Fessia, P; Karppinen, M; Kirby, G; Oberli, L; Perez, J C; Rossi, L; De Rijk, G; Russenschuck, S; Smekens, D; Todesco, E; Tommasini, D

2012-01-01

Beyond HL-LHC, CERN has a number of physics options that offer potential and challenges. This contribution dwells on the long-term projects HE-LHC and LHeC to put the magnet R&D at CERN (resistive and superconducting, slow and fast) in a long-term perspective. In particular synergies and parallel roadmaps will be highlighted. We will show how the on-going development (2012-2015) on low-field, high-field, and low-loss magnets can be used towards longer term objectives.

Deep-water measurements of container ship radiated noise signatures and directionality.

Science.gov (United States)

Gassmann, Martin; Wiggins, Sean M; Hildebrand, John A

2017-09-01

Underwater radiated noise from merchant ships was measured opportunistically from multiple spatial aspects to estimate signature source levels and directionality. Transiting ships were tracked via the Automatic Identification System in a shipping lane while acoustic pressure was measured at the ships' keel and beam aspects. Port and starboard beam aspects were 15°, 30°, and 45° in compliance with ship noise measurements standards [ANSI/ASA S12.64 (2009) and ISO 17208-1 (2016)]. Additional recordings were made at a 10° starboard aspect. Source levels were derived with a spherical propagation (surface-affected) or a modified Lloyd's mirror model to account for interference from surface reflections (surface-corrected). Ship source depths were estimated from spectral differences between measurements at different beam aspects. Results were exemplified with a 4870 and a 10 036 twenty-foot equivalent unit container ship at 40%-56% and 87% of service speeds, respectively. For the larger ship, opportunistic ANSI/ISO broadband levels were 195 (surface-affected) and 209 (surface-corrected) dB re 1 μPa 2 1 m. Directionality at a propeller blade rate of 8 Hz exhibited asymmetries in stern-bow (<6 dB) and port-starboard (<9 dB) direction. Previously reported broadband levels at 10° aspect from McKenna, Ross, Wiggins, and Hildebrand [(2012b). J. Acoust. Soc. Am. 131, 92-103] may be ∼12 dB lower than respective surface-affected ANSI/ISO standard derived levels.

Superconducting magnetic energy storage and superconducting self-supplied electromagnetic launcher

Science.gov (United States)

Ciceron, Jérémie; Badel, Arnaud; Tixador, Pascal

2017-10-01

Superconductors can be used to build energy storage systems called Superconducting Magnetic Energy Storage (SMES), which are promising as inductive pulse power source and suitable for powering electromagnetic launchers. The second generation of high critical temperature superconductors is called coated conductors or REBCO (Rare Earth Barium Copper Oxide) tapes. Their current carrying capability in high magnetic field and their thermal stability are expanding the SMES application field. The BOSSE (Bobine Supraconductrice pour le Stockage d'Energie) project aims to develop and to master the use of these superconducting tapes through two prototypes. The first one is a SMES with high energy density. Thanks to the performances of REBCO tapes, the volume energy and specific energy of existing SMES systems can be surpassed. A study has been undertaken to make the best use of the REBCO tapes and to determine the most adapted topology in order to reach our objective, which is to beat the world record of mass energy density for a superconducting coil. This objective is conflicting with the classical strategies of superconducting coil protection. A different protection approach is proposed. The second prototype of the BOSSE project is a small-scale demonstrator of a Superconducting Self-Supplied Electromagnetic Launcher (S3EL), in which a SMES is integrated around the launcher which benefits from the generated magnetic field to increase the thrust applied to the projectile. The S3EL principle and its design are presented. Contribution to the topical issue "Electrical Engineering Symposium (SGE 2016)", edited by Adel Razek

Hybrid superconducting magnetic suspensions

International Nuclear Information System (INIS)

Tixador, P.; Hiebel, P.; Brunet, Y.; Chaud, X.; Gautier-Picard, P.

1996-01-01

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

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

Anomalous superconductivity in black phosphorus under high pressures

International Nuclear Information System (INIS)

Kawamura, H.; Tachikawa, K.

1984-01-01

Pressure induced superconductivity in single crystals of black phosphorus has been studied. Maximum onset Tsub(c) was near 13 K. The anomalous superconductivity may be explained in terms of excitonic mechanism. (author)

Rotational loss of a ring-shaped flywheel supported by high T{sub c} superconducting levitation

Energy Technology Data Exchange (ETDEWEB)

Teshima, Hidekazu [Nippon Steel Corp., Kawasaki, Kanagawa (Japan). Advanced Materials and Technology Research Labs.; Tawara, Taichi; Shimada, Ryuichi

1997-08-01

This paper describes the experimental results for the rotational loss of a ring-shaped flywheel supported by high T{sub c} superconducting levitation. Superconducting levitation is appropriate for rotating a ring-shaped flywheel which has neither shaft nor hub because it is a non-contact and automatically stable levitation without any control systems. The rotational loss has been investigated using a small-scaled experimental machine consisting of 16 bulk superconductors 46 mm in diameter and a ring-shaped flywheel about 300 mm in diameter. The rotational loss decreased as the levitation gap height increased. In low-speed rotational regions, the rotational loss was in proportion to the rotation speed and depended more on the levitation gap. In high-speed rotational regions, the rotational loss was in proportion to the third power of the rotation speed and depended less on the levitation gap. The cubic rotational loss in He was reduced to one-fifth of that in air. The magnetic field pinned in bulk superconductors induces a loss in the materials composing the ring-shaped flywheel. The rotational loss of a ring-shaped flywheel supported by superconducting levitation can be reduced by improving the uniformity of the magnetic fields along the ring, enlargement of the bulk superconductor(s), and densely arranging the bulk superconductors. (author)

James C. McGroddy Prize Talk: Superconductivity in alkali-metal doped Carbon-60

Science.gov (United States)

Hebard, Arthur

2008-03-01

Carbon sixty (C60), which was first identified in 1985 in laser desorption experiments, is unquestionably an arrestingly beautiful molecule. The high symmetry of the 12 pentagonal and 20 hexagonal faces symmetrically arrayed in a soccer-ball like structure invites special attention and continues to stimulate animated speculation. The availability in 1990 of macroscopic amounts of purified C60 derived from carbon-arc produced soot allowed the growth and characterization of both bulk and thin-film samples. Crystalline C60 is a molecular solid held together by weak van der Waals forces. The fcc structure has a 74% packing fraction thus allowing ample opportunity (26% available volume) for the intercalation of foreign atoms into the interstitial spaces of the three dimensional host. This opportunity catalyzed much of the collaborative work amongst chemists, physicists and materials scientists at Bell Laboratories, and resulted in the discovery of superconductivity in alkali-metal doped C60 with transition temperatures (Tc) in the mid-30-kelvin range. In this talk I will review how the successes of this initial team effort stimulated a worldwide collaboration between experimentalists and theorists to understand the promise and potential of an entirely new class of superconductors containing only two elements, carbon and an intercalated alkali metal. Although the cuprates still hold the record for the highest Tc, there are still open scientific questions about the mechanism that gives rise to such unexpectedly high Tc's in the non-oxide carbon-based superconductors. The doped fullerenes have unusual attributes (e.g., narrow electronic bands, high disorder, anomalous energy scales, and a tantalizing proximity to a metal-insulator Mott transition), which challenge conventional thinking and at the same time provide useful insights into new directions for finding even higher Tc materials. The final chapter of the `soot to superconductivity' story has yet to be written.

Superconductivity of Rock-Salt Structure LaO Epitaxial Thin Film.

Science.gov (United States)

Kaminaga, Kenichi; Oka, Daichi; Hasegawa, Tetsuya; Fukumura, Tomoteru

2018-06-06

We report a superconducting transition in a LaO epitaxial thin film with the superconducting transition onset temperature ( T c ) at around 5 K. This T c is higher than those of other lanthanum monochalcogenides and opposite to their chemical trend: T c = 0.84, 1.02, and 1.48 K for LaX (X = S, Se, Te), respectively. The carrier control resulted in a dome-shaped T c as a function of electron carrier density. In addition, the T c was significantly sensitive to epitaxial strain in spite of the highly symmetric crystal structure. This rock-salt superconducting LaO could be a building block to design novel superlattice superconductors.

Possibility of high temperature superconducting phases in PdH

Energy Technology Data Exchange (ETDEWEB)

Tripodi, Paolo; Di Gioacchino, Daniele; Borelli, Rodolfo; Vinko, Jenny Darja

2003-05-15

Possible new superconducting phases with a high critical transition temperature (T{sub c}) have been found in stable palladium-hydrogen (PdH{sub x}) samples for stoichiometric ratio x=H/Pd{>=}1, in addition to the well-known low critical transition temperature (0{<=}T{sub c}{<=}9) when x is in the range (0.75{<=}x{<=}1.00). Possible new measured superconducting phases with critical temperature in the range 51{<=}T{sub c}{<=}295 K occur. This T{sub c} varies considerably with every milli part of x when x exceeds unit. A superconducting critical current density J{sub c}{>=}6.1x10{sup 4} A cm{sup -2} has been measured at 77 K with H{sub DC}=0 T.

Theory of novel normal and superconducting states in doped oxide high-Tc superconductors

International Nuclear Information System (INIS)

Dzhumanov, S.

2001-10-01

A consistent and complete theory of the novel normal and superconducting (SC) states of doped high-T c superconductors (HTSC) is developed by combining the continuum model of carrier self-trapping, the tight-binding model and the novel Fermi-Bose-liquid (FBL) model. The ground-state energy of carriers in lightly doped HTSC is calculated within the continuum model and adiabatic approximation using the variational method. The destruction of the long-range antiferromagnetic (AF) order at low doping x≥ x cl ≅0.015, the formation of the in-gap states or bands and novel (bi)polaronic insulating phases at x c2 ≅0.06-0.08, and the new metal- insulator transition at x≅x c2 in HTSC are studied within the continuum model of impurity (defect) centers and large (bi)polarons by using the appropriate tight-binding approximations. It is found that the three-dimensional (3d) large (bi)polarons are formed at ε ∞ /ε 0 ≤0.1 and become itinerant when the (bi)polaronic insulator-to-(bi)polaronic metal transitions occur at x x c2 . We show that the novel pseudogapped metallic and SC states in HTSC are formed at x c2 ≤x≤x p ≅0.20-0.24. We demonstrate that the large polaronic and small BCS-like pairing pseudogaps opening in the excitation spectrum of underdoped (x c2 BCS =0.125), optimally doped (x BCS o ≅0.20) and overdoped (x>x o ) HTSC above T c are unrelated to superconductivity and they are responsible for the observed anomalous optical, transport, magnetic and other properties of these HTSC. We develop the original two-stage FBL model of novel superconductivity describing the combined novel BCS-like pairing scenario of fermions and true superfluid (SF) condensation scenario of composite bosons (i.e. bipolarons and cooperons) in any Fermi-systems, where the SF condensate gap Δ B and the BCS-like pairing pseudogap Δ F have different origins. The pair and single particle condensations of attracting 3d and two- dimensional (2d) composite bosons are responsible for

Demonstration of superconducting micromachined cavities

Energy Technology Data Exchange (ETDEWEB)

Brecht, T., E-mail: teresa.brecht@yale.edu; Reagor, M.; Chu, Y.; Pfaff, W.; Wang, C.; Frunzio, L.; Devoret, M. H.; Schoelkopf, R. J. [Department of Applied Physics, Yale University, New Haven, Connecticut 06511 (United States)

2015-11-09

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

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.

Formation region and amplitude of colour superconductivity in an instanton-induced model

CERN Document Server

Liao Jin Feng

2002-01-01

Colour superconductivity is investigated in the frame of a two flavour instanton-induced model. The ratio of diquark to quark-antiquark coupling constants is restricted to be c/(N sub c -1) with 1 <=c <=2.87 and controls the formation region and amplitude of colour superconductivity. While the finite current quark mass changes the chiral transition significantly, it does not considerably change the colour superconductivity

Lattice parameters guide superconductivity in iron-arsenides

Science.gov (United States)

Konzen, Lance M. N.; Sefat, Athena S.

2017-03-01

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.

Conductive polymer switch for controlling superconductivity

International Nuclear Information System (INIS)

McDevitt, J.T.; Haupt, S.G.; Riley, D.R.; Zhao, J.; Grassi, J.; Lo, K.; Jones, C.

1994-01-01

The preparation of a hybrid conducting polymer/high-temperature superconductor device consisting of a polypyrrole coated YBa 2 Cu 3 O 7-σ microbridge is reported. Electrochemical techniques are exploited to alter the oxidation state of the polymer and, in doing so, it is found for the first time that superconductivity can be modulated in a controllable and reproducible fashion by a polymer layout. Whereas the neutral (insulating) polypyrrole only slightly influences the electrical properties of the underlying YBa 2 Cu 3 O 7-σ film, the oxidized (conductive) polymer depresses T c by up to 50K. In a similar fashion, the oxidation state of the polymer is found to reversibly modulate the magnitude of J c , the superconducting critical current. Thus, a new type of molecule switch for controlling superconductivity is demonstrated

Use of high-temperature superconducting films in superconducting bearings

International Nuclear Information System (INIS)

Cansiz, A.

1999-01-01

We have investigated the effect of high-temperature superconductor (HTS) films deposited on substrates that are placed above bulk HTSs in an attempt to reduce rotational drag in superconducting bearings composed of a permanent magnet levitated above the film/bulk HTS combination. According to the critical state model, hysteresis energy loss is inversely proportional to critical current density, J c , and because HTS films typically have much higher J c than that of bulk HTS, the film/bulk combination was expected to reduce rotational losses by at least one order of magnitude in the coefficient of fiction, which in turn is a measure of the hysteresis losses. We measured rotational losses of a superconducting bearing in a vacuum chamber and compared the losses with and without a film present. The experimental results showed that contrary to expectation, the rotational losses are increased by the film. These results are discussed in terms of flux drag through the film, as well as of the critical state model

Development of helium transfer coupling of 1 MW-class HTS motor for podded ship propulsion system

Energy Technology Data Exchange (ETDEWEB)

Kosuge, Eiji; Gocho, Yoshitsugu; Okumura, Kagao; Yamaguchi, Mitsugi [JapaneseSuperconductivity Organization, 135-8533, Tokyo (Japan); Umemoto, Katsuya; Aizawa, Kiyoshi; Yokoyama, Minoru; Takao, Satoru, E-mail: gocho@jso--new-scm.co.j [Kawasaki Heavy Industries LTD., 673-8666, Hyogo (Japan)

2010-06-01

Research and development of 1 MW superconducting motor are being made aiming at the efficiency improvement for the podded type ship propulsion. The basic machine configuration is similar to steam turbine generators, having a rotating horizontal shaft. As for the motor composed of rotating superconducting field, one of the most critical issues is to provide a technically viable helium transfer coupling (HTC). The field winding of 1 MW motor is cooled with cryogenic helium gas. The HTC needs to supply the cryogenic helium gas with an appropriate flow rate from the stationary part to the rotating field winding region through a hollowed shaft in order not to lose superconducting state of the winding. A full size prototype of HTC was developed prior to the actual one to demonstrate its technical acceptability. The fundamental data with regard to the supply of the refrigerated helium gas were successfully obtained at the rated speed. This work has been supported by New Energy, and Industrial Technology Development Organization (NEDO).

Superconductivity Series in Transition Metal Dichalcogenides by Ionic Gating

NARCIS (Netherlands)

Shi, Wu; Ye, Jianting; Zhang, Yijin; Suzuki, Ryuji; Yoshida, Masaro; Miyazaki, Jun; Inoue, Naoko; Saito, Yu; Iwasa, Yoshihiro

2015-01-01

Functionalities of two-dimensional (2D) crystals based on semiconducting transition metal dichalcogenides (TMDs) have now stemmed from simple field effect transistors (FETs) to a variety of electronic and opto-valleytronic devices, and even to superconductivity. Among them, superconductivity is the

Synthesis of high-temperature superconducting oxides and chemical alloying in Cu-O planes

International Nuclear Information System (INIS)

Tarascon, J.M.; Barboux, P.; Bagley, B.G.; Green, L.H.; Mckinnon, W.R.; Hull, G.W.

1988-01-01

Some methods for synthesis permitting to fabricate dense superconducting ceramics are considered. The Zole-Hell method is the most perspective one among them. Effect of oxygen content in a sample and copper substitution for nickel and zinc on structural, transition and superconducting properties of samples of the La-Sr-Cu-O(1) and Y-Ba-Cu-O(2) systems is studied. Copper substitution is established to suppress superconductivity in system 1 and to decrease T c in system 2, and this effect doesn't depend on the fact whether the substituting 3d-metal is magnetic (nickel) or diamagnetic (zinc). Detailed study of YBa 2 Cu 3 O 7-y properties as a function of oxygen content has shown that superconductivty in this composition can be suppressed as a result of oxygen removal and it can be reduced with its interoduction. The possibility to prepare nonalloyed La 2 CuO 4 in superconducting state as a result of plasma treatment comprises a scientific interest. 27 refs.; 5 figs.; 1 tab

Superconducting magnet system for the J-PARC neutrino beam line. Development, construction and operation of superconducting magnets

International Nuclear Information System (INIS)

Sasaki, Ken-ichi; Nakamoto, Tatsushi; Ajima, Yasuo; Okamura, Takahiro; Ogitsu, Toru; Kimura, Nobuhiro; Terashima, Akio; Tomaru, Takayuki; Higashi, Norio

2010-01-01

Superconducting combined-function magnets have been utilized for the 50-GeV, 750-kW proton beam line in the J-PARC neutrino experiment. The magnets are designed to provide a dipole field of 2.6 T combined with a quadrupole field of 19 T/m in a coil aperture of 173.4 mm at a nominal current of 7,345 A. Following the success of a prototype R and D project, a superconducting magnet system for the J-PARC neutrino beam line has been constructed since 2005. Using a new conceptual beam line with the superconducting combined-function magnets has demonstrated successful beam transport to the target neutrino production. (author)

Contrasting dynamic spin susceptibility models and their relation to high-temperature superconductivity

International Nuclear Information System (INIS)

Schuettler, H.; Norman, M.R.

1996-01-01

We compare the normal-state resistivities ρ and the critical temperatures T c for superconducting d x 2 -y 2 pairing due to antiferromagnetic (AF) spin fluctuation exchange in the context of two phenomenological dynamical spin susceptibility models for the cuprate high-T c materials, one based on fits to NMR data on Y-Ba-Cu-O (YBCO) proposed by Millis, Monien, and Pines (MMP) and Monthoux and Pines (MP), and the other based on fits to neutron scattering data on YBCO proposed by Radtke, Ullah, Levin, and Norman (RULN). Assuming comparable electronic bandwidths and resistivities in both models, we show that the RULN model gives a much lower d-wave T c (approx-lt 20 K) than the MMP model (with T c ∼100 K). We demonstrate that these profound differences in the T c close-quote s arise from fundamental differences in the spectral weight distributions of the two model susceptibilities at high (>100 meV) frequencies and are not primarily caused by differences in the calculational techniques employed by MP and RULN. Further neutron scattering experiments, to explore the spectral weight distribution at all wave vectors over a sufficiently large excitation energy range, will thus be of crucial importance to resolve the question whether AF spin fluctuation exchange can provide a viable mechanism to account for high-T c superconductivity. Limitations of the Migdal-Eliashberg approach in such models will be discussed. copyright 1996 The American Physical Society

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.

Superconductivity

International Nuclear Information System (INIS)

Taylor, A.W.B.; Noakes, G.R.

1981-01-01

This book is an elementray introduction into superconductivity. The topics are the superconducting state, the magnetic properties of superconductors, type I superconductors, type II superconductors and a chapter on the superconductivity theory. (WL)

Design and Realization of Ship Fire Simulation Training System Based on Unity3D

Science.gov (United States)

Ting, Ye; Feng, Chen; Wenqiang, Wang; Kai, Yang

2018-01-01

Ship fire training is a very important training to ensure the safety of the ship, but limited by the characteristics of the ship itself, it is difficult to carry out fire training on the ship. This paper proposes to introduce a virtual reality technology to build a set of ship fire simulation training system, used to improve the quality of training, reduce training costs. First, the system design ideas are elaborated, and the system architecture diagram is given. Then, the key technologies in the process of system implementation are analyzed. Finally, the system examples are built and tested.

Superconductivity

International Nuclear Information System (INIS)

Onnes, H.K.

1988-01-01

The author traces the development of superconductivity from 1911 to 1986. Some of the areas he explores are the Meissner Effect, theoretical developments, experimental developments, engineering achievements, research in superconducting magnets, and research in superconducting electronics. The article also mentions applications shown to be technically feasible, but not yet commercialized. High-temperature superconductivity may provide enough leverage to bring these applications to the marketplace

On superconductivity and superfluidity. A scientific autobiography

International Nuclear Information System (INIS)

Ginzburg, Vitaly L.

2009-01-01

This book presents the Nobel Laureate Vitaly Ginzburg's views on the development in the field of superconductivity. It contains a selection of Ginzburg's key writings, including his amended version of the Nobel lecture in Physics 2003. Also included are an expanded autobiography, which was written for the Nobel Committee, an article entitled ''A Scientific Autobiography: An Attempt,'' a fundamental article co-written with L.D. Landau entitled ''To the theory of superconductivity,'' an expanded review article ''Superconductivity and superfluidity (what was done and what was not done),'' and some newly written short articles about superconductivity and related subjects. So, in toto, presented here are the personal contributions of Ginzburg, that resulted in the Nobel Prize, in the context of his scientific biography. (orig.)

On superconductivity and superfluidity a scientific autobiography

CERN Document Server

Ginzburg, Vitalii Lazarevich

2009-01-01

This book presents the Nobel Laureate Vitaly Ginzburg's views on the development in the field of superconductivity. It contains a selection of Ginzburg's key writings, including his amended version of the Nobel lecture in Physics 2003. Also included are an expanded autobiography, which was written for the Nobel Committee, an article entitled "A Scientific Autobiography: An Attempt," a fundamental article co-written with L.D. Landau entitled "To the theory of superconductivity," an expanded review article "Superconductivity and superfluidity (what was done and what was not done)," and some newly written short articles about superconductivity and related subjects. So, in toto, presented here are the personal contributions of Ginzburg, that resulted in the Nobel Prize, in the context of his scientific biography.

A study on the development of high Tc superconducting materials

International Nuclear Information System (INIS)

Won, Dong Yeon; Lee, Hee Gyoun; Kim, Chan Joong

1990-01-01

The microstructure, crystal structure and formation kinetics for the superconducting phases were studied in the lead-doped BiSrCaCuO system. The formation kinetics was also investigated in the samples with different Pb/Bi ratio and it was observed that the 30 % Pb addition is most perferable for the formation of the high T c phase. The formation of the high T c phase was delayed by the excessive addition of Pb. The lattice parameter (c) of the unit cell of both low T c and high T c phases increased with increasing Pb content. Superconducting thin film was sucessfully prepared by chemical vapor deposition (CVD). Film deposited on MgO substrate showed a T c , onset of 85 K and did not reach to zero resistivity down to 77 K. Superconducting 124 phase in Y-system, which is more stable than 123 phase at high temperature showed a T c , onser of 84 K. Additionally, 0.1 mole of Pb, Sn and Ca was substituted for yttrium in 124 phase, respectively. For Pb and Sn-subsituted specimens, 124 phase was formed and for Ca substituted specimen, 124 phase was not formed and revealed no superconductivity down to 77 K. For Sn-substituted specimens, 124 phase was formed but showed no superconductivity down to 77 K. (author)

Development of L-band niobium superconducting RF cavities with high accelerating field

International Nuclear Information System (INIS)

Saito, Kenji; Noguchi, Shuichi; Ono, Masaaki; Kako, Eiji; Shishido, Toshio; Matsuoka, Masanori; Suzuki, Takafusa; Higuchi, Tamawo.

1994-01-01

Superconducting RF cavity is a candidate for the TeV energy e + /e - linear collider of next generation if the accelerating field is improved to 25-30 MV/m and much cost down is achieved in cavity fabrication. Since 1990, KEK has continued R and D of L-band niobium superconducting cavities focusing on the high field issue. A serious problem like Q-degradation due to vacuum discharge came out on the way, however, it has been overcome and presently all of cavities which were annealed at 1400degC achieved the accelerating field of >25 MV/m with enough Qo value. Recent results on single cell cavities are described in this paper. (author)

Elliptical vortex and oblique vortex lattice in the FeSe superconductor based on the nematicity and mixed superconducting orders

Science.gov (United States)

Lu, Da-Chuan; Lv, Yang-Yang; Li, Jun; Zhu, Bei-Yi; Wang, Qiang-Hua; Wang, Hua-Bing; Wu, Pei-Heng

2018-03-01

The electronic nematic phase is characterized as an ordered state of matter with rotational symmetry breaking, and has been well studied in the quantum Hall system and the high-Tc superconductors, regardless of cuprate or pnictide family. The nematic state in high-Tc systems often relates to the structural transition or electronic instability in the normal phase. Nevertheless, the electronic states below the superconducting transition temperature is still an open question. With high-resolution scanning tunneling microscope measurements, direct observation of vortex core in FeSe thin films revealed the nematic superconducting state by Song et al. Here, motivated by the experiment, we construct the extended Ginzburg-Landau free energy to describe the elliptical vortex, where a mixed s-wave and d-wave superconducting order is coupled to the nematic order. The nematic order induces the mixture of two superconducting orders and enhances the anisotropic interaction between the two superconducting orders, resulting in a symmetry breaking from C4 to C2. Consequently, the vortex cores are stretched into an elliptical shape. In the equilibrium state, the elliptical vortices assemble a lozenge-like vortex lattice, being well consistent with experimental results.

Ship noise extends to frequencies used for echolocation by endangered killer whales

Directory of Open Access Journals (Sweden)

Scott Veirs

2016-02-01

Full Text Available Combining calibrated hydrophone measurements with vessel location data from the Automatic Identification System, we estimate underwater sound pressure levels for 1,582 unique ships that transited the core critical habitat of the endangered Southern Resident killer whales during 28 months between March, 2011, and October, 2013. Median received spectrum levels of noise from 2,809 isolated transits are elevated relative to median background levels not only at low frequencies (20–30 dB re 1 µPa2/Hz from 100 to 1,000 Hz, but also at high frequencies (5–13 dB from 10,000 to 96,000 Hz. Thus, noise received from ships at ranges less than 3 km extends to frequencies used by odontocetes. Broadband received levels (11.5–40,000 Hz near the shoreline in Haro Strait (WA, USA for the entire ship population were 110 ± 7 dB re 1 µPa on average. Assuming near-spherical spreading based on a transmission loss experiment we compute mean broadband source levels for the ship population of 173 ± 7 dB re 1 µPa 1 m without accounting for frequency-dependent absorption. Mean ship speed was 7.3 ± 2.0 m/s (14.1 ± 3.9 knots. Most ship classes show a linear relationship between source level and speed with a slope near +2 dB per m/s (+1 dB/knot. Spectrum, 1/12-octave, and 1/3-octave source levels for the whole population have median values that are comparable to previous measurements and models at most frequencies, but for select studies may be relatively low below 200 Hz and high above 20,000 Hz. Median source spectrum levels peak near 50 Hz for all 12 ship classes, have a maximum of 159 dB re 1 µPa2/Hz @ 1 m for container ships, and vary between classes. Below 200 Hz, the class-specific median spectrum levels bifurcate with large commercial ships grouping as higher power noise sources. Within all ship classes spectrum levels vary more at low frequencies than at high frequencies, and the degree of variability is almost halved for classes that have smaller speed

Self-consistent T-matrix theory of superconductivity

Czech Academy of Sciences Publication Activity Database

Šopík, B.; Lipavský, Pavel; Männel, M.; Morawetz, K.; Matlock, P.

2011-01-01

Roč. 84, č. 9 (2011), 094529/1-094529/13 ISSN 1098-0121 R&D Projects: GA ČR GAP204/10/0212; GA ČR(CZ) GAP204/11/0015 Institutional research plan: CEZ:AV0Z10100521 Keywords : superconductivity * T-matrix * superconducting gap * restricted self-consistency Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.691, year: 2011

Modal bifurcation in a high-Tc superconducting levitation system

International Nuclear Information System (INIS)

Taguchi, D; Fujiwara, S; Sugiura, T

2011-01-01

This paper deals with modal bifurcation of a multi-degree-of-freedom high-T c superconducting levitation system. As modeling of large-scale high-T c superconducting levitation applications, where plural superconducting bulks are often used, it can be helpful to consider a system constituting of multiple oscillators magnetically coupled with each other. This paper investigates nonlinear dynamics of two permanent magnets levitated above high-T c superconducting bulks and placed between two fixed permanent magnets without contact. First, the nonlinear equations of motion of the levitated magnets were derived. Then the method of averaging was applied to them. It can be found from the obtained solutions that this nonlinear two degree-of-freedom system can have two asymmetric modes, in addition to a symmetric mode and an antisymmetric mode both of which also exist in the linearized system. One of the backbone curves in the frequency response shows a modal bifurcation where the two stable asymmetric modes mentioned above appear with destabilization of the antisymmetric mode, thus leading to modal localization. These analytical predictions have been confirmed in our numerical analysis and experiments of free vibration and forced vibration. These results, never predicted by linear analysis, can be important for application of high-T c superconducting levitation systems.

Cryogenics Vision Workshop for High-Temperature Superconducting Electric Power Systems Proceedings

International Nuclear Information System (INIS)

Energetics, Inc.

2000-01-01

The US Department of Energy's Superconductivity Program for Electric Systems sponsored the Cryogenics Vision Workshop, which was held on July 27, 1999 in Washington, D.C. This workshop was held in conjunction with the Program's Annual Peer Review meeting. Of the 175 people attending the peer review meeting, 31 were selected in advance to participate in the Cryogenics Vision Workshops discussions. The participants represented cryogenic equipment manufactures, industrial gas manufacturers and distributors, component suppliers, electric power equipment manufacturers (Superconductivity Partnership Initiative participants), electric utilities, federal agencies, national laboratories, and consulting firms. Critical factors were discussed that need to be considered in describing the successful future commercialization of cryogenic systems. Such systems will enable the widespread deployment of high-temperature superconducting (HTS) electric power equipment. Potential research, development, and demonstration (RD and D) activities and partnership opportunities for advancing suitable cryogenic systems were also discussed. The workshop agenda can be found in the following section of this report. Facilitated sessions were held to discuss the following specific focus topics: identifying Critical Factors that need to be included in a Cryogenics Vision for HTS Electric Power Systems (From the HTS equipment end-user perspective) identifying R and D Needs and Partnership Roles (From the cryogenic industry perspective) The findings of the facilitated Cryogenics Vision Workshop were then presented in a plenary session of the Annual Peer Review Meeting. Approximately 120 attendees participated in the afternoon plenary session. This large group heard summary reports from the workshop session leaders and then held a wrap-up session to discuss the findings, cross-cutting themes, and next steps. These summary reports are presented in this document. The ideas and suggestions raised during

Correlated Dirac particles and superconductivity on the honeycomb lattice

Science.gov (United States)

Wu, Wei; Scherer, Michael M.; Honerkamp, Carsten; Le Hur, Karyn

2013-03-01

We investigate the properties of the nearest-neighbor singlet pairing and the emergence of d-wave superconductivity in the doped honeycomb lattice considering the limit of large interactions and the t-J1-J2 model. First, by applying a renormalized mean-field procedure as well as slave-boson theories which account for the proximity to the Mott-insulating state, we confirm the emergence of d-wave superconductivity, in agreement with earlier works. We show that a small but finite J2 spin coupling between next-nearest neighbors stabilizes d-wave symmetry compared to the extendeds-wave scenario. At small hole doping, to minimize the energy and to gap the whole Fermi surface or all the Dirac points, the superconducting ground state is characterized by a d+id singlet pairing assigned to one valley and a d-id singlet pairing to the other, which then preserves time-reversal symmetry. The slightly doped situation is distinct from the heavily doped case (around 3/8 and 5/8 filling) supporting a pure chiral d+id symmetry and breaking time-reversal symmetry. Then, we apply the functional renormalization group and study in more detail the competition between antiferromagnetism and superconductivity in the vicinity of half filling. We discuss possible applications to strongly correlated compounds with copper hexagonal planes such as In3Cu2VO9. Our findings are also relevant to the understanding of exotic superfluidity with cold atoms.

Wallops Ship Surveillance System

Science.gov (United States)

Smith, Donna C.

2011-01-01

Approved as a Wallops control center backup system, the Wallops Ship Surveillance Software is a day-of-launch risk analysis tool for spaceport activities. The system calculates impact probabilities and displays ship locations relative to boundary lines. It enables rapid analysis of possible flight paths to preclude the need to cancel launches and allow execution of launches in a timely manner. Its design is based on low-cost, large-customer- base elements including personal computers, the Windows operating system, C/C++ object-oriented software, and network interfaces. In conformance with the NASA software safety standard, the system is designed to ensure that it does not falsely report a safe-for-launch condition. To improve the current ship surveillance method, the system is designed to prevent delay of launch under a safe-for-launch condition. A single workstation is designated the controller of the official ship information and the official risk analysis. Copies of this information are shared with other networked workstations. The program design is divided into five subsystems areas: 1. Communication Link -- threads that control the networking of workstations; 2. Contact List -- a thread that controls a list of protected item (ocean vessel) information; 3. Hazard List -- threads that control a list of hazardous item (debris) information and associated risk calculation information; 4. Display -- threads that control operator inputs and screen display outputs; and 5. Archive -- a thread that controls archive file read and write access. Currently, most of the hazard list thread and parts of other threads are being reused as part of a new ship surveillance system, under the SureTrak project.

Theory of superconductivity

International Nuclear Information System (INIS)

Crisan, M.

1988-01-01

This book discusses the most important aspects of the theory. The phenomenological model is followed by the microscopic theory of superconductivity, in which modern formalism of the many-body theory is used to treat most important problems such as superconducting alloys, coexistence of superconductivity with the magnetic order, and superconductivity in quasi-one-dimensional systems. It concludes with a discussion on models for exotic and high temperature superconductivity. Its main aim is to review, as complete as possible, the theory of superconductivity from classical models and methods up to the 1987 results on high temperature superconductivity. Contents: Phenomenological Theory of Superconductivity; Microscopic Theory of Superconductivity; Theory of Superconducting Alloys; Superconductors in a Magnetic Field; Superconductivity and Magnetic Order; Superconductivity in Quasi-One-Dimensional Systems; and Non-Conventional Superconductivity

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

Design of a superconducting wiggler system

International Nuclear Information System (INIS)

Shen, S.S.; Miller, J.R.; Heim, J.R.; Slack, D.S.

1988-01-01

We present a wiggler system based on currently available superconducting technology. The system is designed to provide maximum central field of 4.4 tesla with a specified period length of 160 mm and a gap of 40 mm, while meeting the field quality requirements along all axes. Also included are preliminary cost estimates and a survey of world-wide RandD efforts on superconducting wiggler systems. 12 refs., 6 figs., 3 tabs

Simulation software of 3-D two-neutron energy groups for ship reactor with hexagonal fuel subassembly

International Nuclear Information System (INIS)

Zhang Fan; Cai Zhangsheng; Yu Lei; Gui Xuewen

2005-01-01

Core simulation software for 3-D two-neutron energy groups is developed. This software is used to simulate the ship reactor with hexagonal fuel subassembly after 10, 150 and 200 burnup days, considering the hydraulic and thermal feedback. It accurately simulates the characteristics of the fast and thermal neutrons and the detailed power distribution in a reactor under normal and abnormal operation condition. (authors)

Transport currents along c-axis and (a,b) planes in YBCO single domain materials. Critical current densities and normal-superconducting transitions

International Nuclear Information System (INIS)

Porcar, L.; Bourgault, D.; Chaud, X.; Noudem, J.G.; Tournier, R.; Tixador, P.

1998-01-01

High transport currents along the (a,b) planes and along the c-axis have been measured in pulsed current of different pseudo-frequencies. Self field losses and transport current of 8000 A (20000 A cm -2 ) have been measured in Y 1 Ba 2 Cu 3 O 7-δ bars textured by the melting zone technique. Critical currents as high as 500 A (90000 A cm -2 ) along the (a,b) planes or 3000 A (7500 A cm -2 ) along the c-axis have been measured. For both orientations, the transition from the normal state to the superconducting state has been observed. Electric field of 1000 V m -1 and study of the superconducting state recovery are reported. (orig.)

Oxide superconducting ribbon and its fabrication process

International Nuclear Information System (INIS)

Belouet, C.

1990-01-01

A film without cavities, of perovskite type superconducting oxide is deposited by melting on a metal or composite flexible substrate with a rectangular cross section. The film thickness is comprised between 1 and 100 micrometers and orientation of C axis of superconducting crystals is perpendicular to the subtrate [fr

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.

Superconducting Fluctuations above T c and pair breaking parameters of two dimensional Niobium Nitride Films

Science.gov (United States)

Shinozaki, B.; Ezaki, S.; Odou, T.; Makise, K.; Asano, T.

2018-03-01

Transport properties have been investigated for the epitaxial superconducting NbN thin films. We analysed the excess conductance σ’ ≡ σ(T) - σN by the sum of the Aslamazov-Larkin (AL) and Maki-Thompson (MT) terms for thermal fluctuations above T c, where the σN ≡1/R sq N is the normal state sheet conductance. We have found that the theoretical expression σ’theo (T) = σ’AL (T) + σ’MT (T,δ) can be well fitted to σ’exp (T) with use of the suitable value of the pair breaking parameter δ in the MT term relating to the inelastic scattering rate 1/τin(T) as δ = πħ/8k B Tτin. The rate 1/τin(T) given by the sum of 1/τfluc(T), 1/τe-e(T) and 1/τe-ph (T) is determined from the analysis of the magneto-conductance Δσ = σ(H) – σ(0) by the sum of AL, MT and the localization terms, where the first, second and third terms correspond to the rate due to the superconducting fluctuation effect, electron-electron and electron-phonon interactions, respectively. The R sq N dependence of δ is expressed by δ = δ0 + αR sq N, where the first term δ0 due to 1/τe-ph (T) and the second term due to the sum of 1/τfluc(T) and 1/τe-e(T). Although we obtained a reasonable value of Debye temperature ΘD ≈630 K from the δ0, the magnitude of the α is about 5 times larger than the theoretical value.

Bi-based superconducting fibers with high critical parameters

International Nuclear Information System (INIS)

Huo Yujing; He Yusheng; Liu Menglin; Mao Sining; Cai Liying; Wang Ying; Zhang Jincang; He Aisheng; Wang Jinsong

1991-01-01

Superconducting fibers of Bi(Pb)-Sr-Ca-Cu-O high Tc superconducting materials have been prepared by means of the laser-heated pedestal growth (LHPG) method. The highest zero resistance temperature T c0 reaches is 114K, and the highest critical current density J c (77K, O T) is greater than 5000 A/cm 2 . As-grown superconducting fibers were successfully fabricated without post growth heat treatment. Amorphous materials were used for the first time to make high quality fibers. The influence of growth conditions, thermal treatment and the composition of the fibers were discussed. (author). 5 refs., 7 figs., 3 tabs

Analysis of a ship-to-ship collision

International Nuclear Information System (INIS)

Porter, V.L.; Ammerman, D.J.

1996-01-01

Sandia National Laboratories is involved in a safety assessment for the shipment of radioactive material by sea. One part of this study is investigation of the consequences of ship-to-ship collisions. This paper describes two sets of finite element analyses performed to assess the structural response of a small freighter and the loading imparted to radioactive material (RAM) packages during several postulated collision scenarios with another ship. The first series of analyses was performed to evaluate the amount of penetration of the freighter hull by a striking ship of various masses and initial velocities. Although these analyses included a representation of a single RAM package, the package was not impacted during the collision so forces on the package could not be computed. Therefore, a second series of analyses incorporating a representation of a row of seven packages was performed to ensure direct package impact by the striking ship. Average forces on a package were evaluated for several initial velocities and masses of the striking ship. In addition to. providing insight to ship and package response during a few postulated ship collisions scenarios, these analyses will be used to benchmark simpler ship collision models used in probabilistic risk assessment analyses

Superconductivity of the two-dimensional Penson-Kolb model

International Nuclear Information System (INIS)

Czart, W.R.; Robaszkiewicz, S.

2001-01-01

Two-dimensional (d = 2) Penson-Kolb model, i.e. the tight-binding model with the pair-hopping (intersite charge exchange) interaction, is considered and the effects of phase fluctuations on the s-wave superconductivity of this system are discussed within Kosterlitz-Thouless scenario. The London penetration depth λ at T = 0, the Kosterlitz Thouless critical temperature T c , and the Hartree-Fock approximation critical temperature T p are determined as a function of particle concentration and interaction. The Uemura type plots (T c vs. λ -2 (0)) are derived. Beyond weak coupling and for low concentrations they show the existence of universal scaling: T c ∼ 1/λ 2 (0), as it previously found for the attractive Hubbard model and for the models intersite electron pairing. (author)

Quantum Theory of Conducting Matter Superconductivity and Quantum Hall Effect

CERN Document Server

Fujita, Shigeji; Godoy, Salvador

2009-01-01

Explains major superconducting properties including zero resistance, Meissner effect, sharp phase change, flux quantization, excitation energy gap, and Josephson effects using quantum statistical mechanical calculations. This book covers the 2D superconductivity and the quantum Hall effects

A Ship Cargo Hold Inspection Approach Using Laser Vision Systems

OpenAIRE

SHEN Yang; ZHAO Ning; LIU Haiwei; MI Chao

2013-01-01

Our paper represents a vision system based on the laser measurement system (LMS) for bulk ship inspection. The LMS scanner with 2-axis servo system is installed on the ship loader to build the shape of the ship. Then, a group of real-time image processing algorithms are implemented to compute the shape of the cargo hold, the inclination angle of the ship and the relative position between the ship loader and the cargo hold. Based on those computed inspection data of the ship, the ship loader c...

Effect of superconducting correlation on the localization of quasiparticles in low dimensions

International Nuclear Information System (INIS)

Xiang, T.

1995-01-01

Localization lengths of superconducting quasiparticles λ s are evaluated and compared with the corresponding normal-state values λ n in one-dimensional (1D) and two-dimensional lattices. The effect of superconducting correlation on the localization of quasiparticles is generally stronger in an off-site pairing state than in an on-site pairing state. The modification of superconducting correlation to λ is strongly correlated with the density of states (DOS) of superconducting quasiparticles. λ s drops within the energy gap but is largely enhanced around energies where DOS peaks appear. For a gapless pairing state in 1D or a d-wave pairing state in 2D, λ s /λ n at the Fermi energy E F is of order 1 and determined purely by the value of gap parameter not by the random potential. For the d-wave pairing state, the localization effect is largely weakened compared with the corresponding normal state and quasiparticles with energies close to E F are more strongly localized than other low-energy quasiparticles

Superheavy element research at the velocity filter ship

International Nuclear Information System (INIS)

Heinz, S.

2012-01-01

The Separator for Heavy Ion Reaction Products (SHIP) is a velocity filter located at the UNILAC accelerator of GSI Darmstadt, Germany. For about 35 years a broad experimental program in the field of superheavy element research is running at SHIP. During the last years particularly investigations in the region of the heaviest known nuclei were performed. In fusion reactions of 48 Ca + 248 Cm → 296 116* a total of six decay chains was observed which could be attributed to the evaporation residues 292 116 and 293 116. In this experiment, data measured previously on the same isotopes in Dubna were well confirmed. Besides, two attempts were made to synthesize isotopes of the still unobserved element Z = 120 in reactions of 64 Ni + 238 U and 54 Cr + 248 Cm. No events were observed in these experiments leading to one-event cross-section limits of 90 fb and 560 fb, respectively. For future superheavy element research, a new superconducting continuous wave LINAC is planned at GSI which shall deliver beam intensities of up to 1014 particles per second. In this context we are developing a next generation separator and new detection techniques

On superconductivity and superfluidity. A scientific autobiography

Energy Technology Data Exchange (ETDEWEB)

Ginzburg, Vitaly L. [Russian Academy of Sciences, Moscow (Russian Federation). P.N. Lebedev Physical Inst.

2009-07-01

This book presents the Nobel Laureate Vitaly Ginzburg's views on the development in the field of superconductivity. It contains a selection of Ginzburg's key writings, including his amended version of the Nobel lecture in Physics 2003. Also included are an expanded autobiography, which was written for the Nobel Committee, an article entitled 'A Scientific Autobiography: An Attempt,' a fundamental article co-written with L.D. Landau entitled 'To the theory of superconductivity,' an expanded review article 'Superconductivity and superfluidity (what was done and what was not done),' and some newly written short articles about superconductivity and related subjects. So, in toto, presented here are the personal contributions of Ginzburg, that resulted in the Nobel Prize, in the context of his scientific biography. (orig.)

Thermal Evaluation of a KRI-BGM Shipping Cask

International Nuclear Information System (INIS)

Bang, K. S.; Lee, J. C.; Seo, K. S.

2007-01-01

Radioactive isotopes are used extensively in the fields of industry, medical treatment, food and agriculture. Use of radioactive isotopes is expected to increase continuously with the growth of each field. In order to safely transport radioactive isotopes from the place of manufacture to the place of use, a shipping package is required. Therefore KAERI is developing the KRI-BGM shipping cask to transport the Ir-192 bulk radioactive material, which is produced at the HANARO research reactor. The shipping package should satisfy the requirements which are prescribed in the Korea MOST Act 2001-23, IAEA Safety Standard Series No. TS-R-1, US 10 CFR Part 71 and the US 49 CFR Part 173. These regulatory classify the KRI-BGM shipping cask as a Type B package, and their regulatory guidelines state that the Type B package for transporting radioactive materials should be able to withstand a period of 30 minutes under a thermal condition of 800 .deg. C. However, the polyurethane, which is to be used as the filling within the cavity of the KRIBGM shipping cask, has a very weak characteristic in a high temperature. Therefore it is difficult for the depleted uranium(hereafter DU), which is used as shielding material, to be protected under a thermal condition of 800 .deg. C. Accordingly, the KRI-BGM shipping cask, which applied non-combustible polyurethane and fireproof materials as the filling, was fabricated. The thermal tests by using prototype cask have been performed to estimate the thermal integrity of the KRI-BGM shipping cask under a thermal condition of 800 .deg. C

Superconductivity

International Nuclear Information System (INIS)

Caruana, C.M.

1988-01-01

Despite reports of new, high-temperature superconductive materials almost every day, participants at the First Congress on Superconductivity do not anticipate commercial applications with these materials soon. What many do envision is the discovery of superconducting materials that can function at much warmer, perhaps even room temperatures. Others hope superconductivity will usher in a new age of technology as semiconductors and transistors did. This article reviews what the speakers had to say at the four-day congress held in Houston last February. Several speakers voiced concern that the Reagan administration's apparent lack of interest in funding superconductivity research while other countries, notably Japan, continue to pour money into research and development could hamper America's international competitiveness

Analysis of the Landing Ship Tank (LST) and its Influence on Amphibious Warfare During World War Two

Science.gov (United States)

2013-12-13

should be conducted. He stressed that the rapid deployment of troops from ship to shore was essential. In February 1924, the Navy and Marine Corps...Figure 12). This allowed for a more rapid loading 96Alfred Dunlop Bailey, “ Alligators , Buffaloes, and Bushmasters: The History of the Development of the...of the wounded, they were adequate for 110A. K. Demetriades, M. C. Gavalas, and J. Ryan, “D-Day On Board A Tank Landing Ship: Meat, Cheese and Blood

Evidence of incomplete annealing at 800 °C and the effects of 120 °C baking on the crystal orientation and the surface superconducting properties of cold-worked and chemically polished Nb

Science.gov (United States)

Sung, Z.-H.; Dzyuba, A.; Lee, P. J.; Larbalestier, D. C.; Cooley, L. D.

2015-07-01

High-purity niobium rods were cold-worked by wire-drawing, followed by various combinations of chemical polishing and high-vacuum baking at 120 °C or annealing at 800 °C in order to better understand changes to the surface superconducting properties resulting from typical superconducting radio-frequency cavity processing. AC susceptibility measurements revealed an enhanced upper transition Tc at ˜ 9.3-9.4 K in all samples that was stable through all annealing steps, a value significantly above the accepted Tc of 9.23 K for pure annealed niobium. Corresponding elevations were seen in the critical fields, the ratio of the surface critical field Hc3 to the bulk upper critical field Hc2 rising to 2.3, well above the Ginzburg-Landau value of 1.695. Orientation imaging revealed an extensive dislocation rich sub-grain structure in the as-drawn rods, a small reduction of the surface strain after baking at 120 °C, and a substantial but incomplete recrystallization near the surface after annealing at 800 °C. We interpret these changes in surface superconducting and structural properties to extensive changes in the near-surface interstitial contamination produced by baking and annealing and to synergistic interactions between H and surface O introduced during electropolishing and buffered chemical polishing.

Superconductivity

International Nuclear Information System (INIS)

Anon.

1988-01-01

This book profiles the research activity of 42 companies in the superconductivity field, worldwide. It forms a unique and comprehensive directory to this emerging technology. For each research site, it details the various projects in progress, analyzes the level of activity, pinpoints applications and R and D areas, reviews strategies and provides complete contact information. It lists key individuals, offers international comparisons of government funding, reviews market forecasts and development timetables and features a bibliography of selected articles on the subject

Superconducting transition and low-field magnetoresistance of a niobium single crystal at 4.2 deg. K; Transition supraconductrice et magnetoresistance en champ faible d'un echantillon monocristallin de niobium a 4.2 deg. K

Energy Technology Data Exchange (ETDEWEB)

Perriot, G. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires. Service de physique du solide et de resonnance magnetique

1967-01-01

We report the study of the electrical resistance of a niobium single crystal, at 4.2 deg. K, from the beginning of the superconductive transition to 80 kilo oersteds. Critical fieldsH{sub c2} and H{sub c3} have been determined. Influences on superconductive transition of current density, field-current angle, crystal orientation and magnetoresistance have been studied. Variation laws of low-field transverse and longitudinal magneto-resistances have been determined. (author) [French] La variation de la resistance electrique d'un monocristal cylindrique de niobium a ete etudiee, a 4,2 deg. K, depuis le debut de la transition supraconductrice jusqu'a 80 kilooersteds. Les champs critiques H{sub c2} et H{sub c3} ont ete determines. On a etudie l'influence de la densite de courant, de l'angle champ-courant, de l'anisotropie cristalline et de la magnetoresistance sur la transition supraconductrice. Les lois de variation des magnetoresistances transversale et longitudinale ont ete determinees dans le domaine des champs faibles. (auteur)

Probing the unconventional superconducting state of LiFeAs by quasiparticle interference.

Science.gov (United States)

Hänke, Torben; Sykora, Steffen; Schlegel, Ronny; Baumann, Danny; Harnagea, Luminita; Wurmehl, Sabine; Daghofer, Maria; Büchner, Bernd; van den Brink, Jeroen; Hess, Christian

2012-03-23

A crucial step in revealing the nature of unconventional superconductivity is to investigate the symmetry of the superconducting order parameter. Scanning tunneling spectroscopy has proven a powerful technique to probe this symmetry by measuring the quasiparticle interference (QPI) which sensitively depends on the superconducting pairing mechanism. A particularly well-suited material to apply this technique is the stoichiometric superconductor LiFeAs as it features clean, charge neutral cleaved surfaces without surface states and a relatively high T(c)∼18  K. Our data reveal that in LiFeAs the quasiparticle scattering is governed by a van Hove singularity at the center of the Brillouin zone which is in stark contrast to other pnictide superconductors where nesting is crucial for both scattering and s(±) superconductivity. Indeed, within a minimal model and using the most elementary order parameters, calculations of the QPI suggest a dominating role of the holelike bands for the quasiparticle scattering. Our theoretical findings do not support the elementary singlet pairing symmetries s(++), s(±), and d wave. This brings to mind that the superconducting pairing mechanism in LiFeAs is based on an unusual pairing symmetry such as an elementary p wave (which provides optimal agreement between the experimental data and QPI simulations) or a more complex order parameter (e.g., s+id wave symmetry).

Superconductive energy storage magnet study

International Nuclear Information System (INIS)

Rhee, S.W.

1982-01-01

Among many methods of energy storages the superconducting energy storage has been considered as the most promising method. Many related technical problems are still unsolved. One of the problems is the magnetizing and demagnetizing loss of superconducting coil. This loss is mainly because of hysteresis of pinning force. In this paper the hysteresis loss is calculated and field dependence of the a.c. losses is explained. The ratio of loss and stored energy is also calculated. (Author)

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.)

Mapping the Superconducting Anti-ferromagnetic C4 Phase in Iron-Pnictides

Science.gov (United States)

Stadel, Ryan; Taddei, Keith; Bugaris, Dan; Lapidus, Saul; Claus, Helmut; Phelan, Daniel; Chung, Duck Young; Kanatzidis, Mercouri; Osborn, Raymond; Rosenkranz, Stephan; Chmaissem, Omar

Following the discovery of the microscopic coexistence of antifermagnetic spin density waves and superconductivity in Ba1-xKxFe2As2 and the low temperature re-entrance to the novel magnetic C4 tetragonal phase in Ba1-xNaxFe2As2, there has been significant interest in developing an understanding of the properties and formation of these phases and analyzing their dependence on temperature and composition in hole-doped 122 alkaline earth metal/iron-pnictides. We describe the mapping of various Ba, Sr, and Ca 122 phase diagrams with systematically controlled levels of hole-doping of alkaline metal onto the alkaline earth metal site, which was investigated via x-ray and neutron diffraction. Our elaborate synthesis, diffraction work, and analysis maps and firmly establishes the C4 phase space in these ternary diagrams as well as the boundary lines that separate the individual phases, and provides natural clues as well as a framework to investigate the stability and formation of the C4 domes that shift location with doping contents in the phase diagrams. Work at Argonne was supported by US DOE, Office of Science, Materials Sciences and Engineering Division.

Forecasting of superconducting compounds

International Nuclear Information System (INIS)

Savitskii, E.M.; Gribulya, V.G.; Kiseleva, N.N.

1981-01-01

In forecasting new superconducting intermetallic compounds of the A15 and Mo 3 Se types most promising from the viewpoint of high critical temperature Tsub(c), high critical magnetic fields Hsub(c), and high critical currents and in estimating their transition temperature it is proposed to apply cybernetic methods of computer learning

Reassessment of the electronic state, magnetism, and superconductivity in high-T{sub c} cuprates with the Nd{sub 2}CuO{sub 4} structure

Energy Technology Data Exchange (ETDEWEB)

Naito, Michio, E-mail: minaito@cc.tuat.ac.jp [Department of Applied Physics, Tokyo University of Agriculture and Technology, Naka-cho 2-24-16, Koganei, Tokyo 184-8588 (Japan); Krockenberger, Yoshiharu; Ikeda, Ai; Yamamoto, Hideki [NTT Basic Research Laboratories, NTT Corporation, 3-1 Morinosato-Wakamiya, Atsugi, Kanagawa 243-0198 (Japan)

2016-04-15

Highlights: • The 30-year history of “electron-doped” cuprates is reviewed, including basic physics and material issues. • Undoped cuprates with the Nd{sub 2}CuO{sub 4} (T’) structure are superconducting with T{sub c} over 30 K. • Electron doping by Ce in T’-RE{sub 2}CuO{sub 4} lowers T{sub c} and the highest T{sub c} is obtained at no doping. - Abstract: The electronic phase diagram of the cuprates remains enigmatic and is still a key ingredient to understand the mechanism of high-T{sub c} superconductivity. It has been believed for a long time that parent compounds of cuprates were universally antiferromagnetic Mott insulators (charge-transfer insulators) and that high-T{sub c} superconductivity would develop upon doping holes or electrons in a Mott–Hubbard insulator (“doped Mott-insulator scenario”). However, our recent discovery of superconductivity in the parent compounds of square-planar cuprates with the Nd{sub 2}CuO{sub 4} (T’) structure and the revised electronic phase diagram in T’ cuprates urged a serious reassessment to the above scenario. In this review, we present the main results derived from our synthesis and experiments on T’ cuprates in the undoped or heavily underdoped regime over 20 years, including material issues and basic physics. The key material issue is how to remove excess oxygen ions at the apical site without introducing oxygen vacancies in the CuO{sub 2} planes. In order to put this into practice, the basic knowledge of complex solid-state chemistry in T’ cuprates is required, which is also included in this review.

Structure and Properties of the Nonface-Spiral Fullerenes T-C380, D3-C384, D3-C440, and D3-C672 and Their Halma and Leapfrog Transforms

DEFF Research Database (Denmark)

Wirz, Lukas; Tonner, Ralf; Avery, James Emil

2013-01-01

The structure and properties of the three smallest nonface-spiral (NS) fullerenes NS-T-C380, NS-D3-C384, NS-D3-C440, and the first isolated pentagon NS-fullerene, NS-D3-C672, are investigated in detail. They are constructed by either a generalized face-spiral algorithm or by vertex insertions......-fullerenes compared to C60, but, as expected, in a lower stability than most stable isomers. None of the many investigated halma transforms on nonspiral fullerenes, NS-T-C380, NS-D3-C384, NS-D3-C440, and NS-D3-C672, admit any spirals, and we conjecture that all halma transforms of NS-fullerenes belong to the class...

Competition/coexistence of magnetism and superconductivity in iron pnictides probed by muon spin rotation

International Nuclear Information System (INIS)

Takeshita, Soshi; Kadono, Ryosuke

2009-01-01

The presence of macroscopic phase separation into superconducting and magnetic phases in LaFeAsO 1-x F x and CaFe 1-x Co x AsF is demonstrated by muon spin rotation (μSR) measurement across their phase boundaries (x=0.06 for LaFeAsO 1-x F x and x=0.075-0.15 for CaFe 1-x Co x AsF). In LaFeAsO 0.94 F 0.06 , both magnetism and superconductivity develop simultaneously below a common critical temperature, T m ≅T c ≅18 K, where the magnetism is characterized by strong randomness. A similar, but more distinct segregation of these two phases is observed in CaFe 1-x Co x AsF, where the magnetic phase retains T m close to that of the parent compound (T c m ≅80-120 K) and the superconducting volume fraction is mostly proportional to the Co content x. The close relationship between magnetism and superconductivity is discussed based on these experimental observations. Concerning the superconducting phase, an assessment is made on the anisotropy of the order parameter in the superconducting state of LaFeAsO 1-x F x , CaFe 1-x Co x AsF and Ba 1-x K x Fe 2 As 2 (x=0.4) based on the temperature dependence of superfluid density [n s (T)] measured by μSR. The gap parameter, 2Δ/k B T c , determined from n s (T) exhibits a tendency that values in the hole-doped pnictides (Ba 1-x K x Fe 2 As 2 ) are much greater than those in electron-doped ones (LaFeAsO 1-x F x and CaFe 1-x Co x AsF), suggesting a difference in the coupling to bosons mediating the Cooper pairs between relevant d electron bands.

Towards Real Time Simulation of Ship-Ship Interaction

DEFF Research Database (Denmark)

Lindberg, Ole; Bingham, Harry B.; Engsig-Karup, Allan Peter

2012-01-01

We present recent and preliminary work directed towards the development of a simplified, physics-based model for improved simulation of ship-ship interaction that can be used for both analysis and real-time computing (i.e. with real-time constraints due to visualization). The goal is to implement...... accurate (realistic) and much faster ship-wave and ship-ship simulations than are currently possible. The coupling of simulation with visualization should improve the visual experience such that it can be perceived as more realistic in training. Today the state-of-art in real-time ship-ship interaction...... is for efficiency reasons and time-constraints in visualization based on model experiments in towing tanks and precomputed force tables. We anticipate that the fast, and highly parallel, algorithm described by Engsig-Karup et al. [2011] for execution on affordable modern high-throughput Graphics Processing Units...

Coexistence of incommensurate magnetism and superconductivity in the two-dimensional Hubbard model

Energy Technology Data Exchange (ETDEWEB)

Yamase, Hiroyuki [Max Planck Institute for Solid State Research, Stuttgart (Germany); National Institute for Materials Science, Tsukuba (Japan); Eberlein, Andreas [Max Planck Institute for Solid State Research, Stuttgart (Germany); Department of Physics, Harvard University, Cambridge (United States); Metzner, Walter [Max Planck Institute for Solid State Research, Stuttgart (Germany)

2016-07-01

We analyze the competition of magnetism and superconductivity in the two-dimensional Hubbard model with a moderate interaction strength, including the possibility of incommensurate spiral magnetic order. Using an unbiased renormalization group approach, we compute magnetic and superconducting order parameters in the ground state. In addition to previously established regions of Neel order coexisting with d-wave superconductivity, the calculations reveal further coexistence regions where superconductivity is accompanied by incommensurate magnetic order.

Strong-coupling d-wave superconductivity in PuCoGa.sub.5./sub. probed by point-contact spectroscopy

Czech Academy of Sciences Publication Activity Database

Daghero, D.; Tortello, M.; Ummarino, G.A.; Griveau, J.C.; Colineau, E.; Eloirdi, R.; Shick, Alexander; Kolorenč, Jindřich; Lichtenstein, A.I.; Caciuffo, R.

2012-01-01

Roč. 3, Apr (2012), "786-1"-"786-8" ISSN 2041-1723 R&D Projects: GA ČR(CZ) GAP204/10/0330; GA AV ČR IAA100100912 Institutional research plan: CEZ:AV0Z10100520 Keywords : superconductivity * PuCoGa 5 * magnetism Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 10.015, year: 2012 http://www.nature.com/ncomms/journal/v3/n4/full/ncomms1785.html

Multiple superconducting transition and phase separation in melt-textured YBa{sub 2}Cu{sub 3}O{sub 7−d}

Energy Technology Data Exchange (ETDEWEB)

Menegotto Costa, R. [Instituto de Matemática, Estatística e Física, Universidade Federal do Rio Grande (FURG), Campus Carreiros, Rio Grande, RS (Brazil); Dias, F.T. [Instituto de Física e Matemática, Universidade Federal de Pelotas (UFPel), Caixa Postal 354, 96010-900 Pelotas, RS (Brazil); Pureur, P., E-mail: ppureur@if.ufrgs.br [Instituto de Física, Universidade Federal do Rio Grande do Sul (UFRGS), Caixa Postal 15051, 91501-970 Porto Alegre, RS (Brazil); Obradors, X. [Institut de Ciéncia de Materials de Barcelona, CSIC, Universitat Autònoma de Barcelona, 08193 Bellaterra (Spain)

2013-12-15

Highlights: •We report on experimental measurements of the temperature derivative of the resistivity in the region encompassing the superconducting transition in melt-textured samples of the YBa{sub 2}Cu{sub 3}O{sub 7−d} cuprate superconductor. •A complex and subtle multi-peak structure is observed in d{ρ}/dT. •We develop a new method to quantitatively describe the resistive transition of a multi-phased superconductor. •The pseudo-spectral structure observed in d{ρ}/dT is ascribed to a phase separation phenomenon driven by the ordering of labile oxygen atoms in the Cu–O chain substructure. -- Abstract: We report on careful measurements of the temperature derivative of the resistivity, dρ/dT, in the region encompassing the superconducting transition of melt-textured samples of the YBa{sub 2}Cu{sub 3}O{sub 7−d} cuprate superconductor. Measurements were carried out in orientations parallel and perpendicular to the Cu − O{sub 2} atomic planes in the presence of small magnetic fields applied parallel to the current orientation. The dρ/dT results reveal the occurrence of complex multi-peak structures that were analyzed with a new method based on the assumption that a simple series association of conductivities is adequate for describing the resistive transition of multiphased superconductors. We ascribe the multi-peak structure observed in the derivative measurements to a subtle and complex phase separation phenomenon leading to the stabilization of domains having slightly different electronic properties that are related to the ordering of labile oxygen atoms in the YBa{sub 2}Cu{sub 3}O{sub 7−d} chain sub-structure.

Nanolayers with advanced properties for superconducting nanoelectronics

International Nuclear Information System (INIS)

Prepelita, A.; Zdravkov, V.; Morari, R.; Socrovisciuc, A.; Antropov, E.; Sidorenko, A.

2011-01-01

Full text: Elaborated advanced technology for superconducting spintronics - technological process, based on magnetron sputtering of the metallic films with non-metallic protective layers, yields significant improvement in superconducting properties of thin Nb films and Nb/CuNi nanostructures in comparison with common methods of films deposition. The developed advanced technological process is patented (Patent RM number 175 from 31.03.2010). First experimental observation of the double re-entrant superconductivity in superconductor/ ferromagnetic nanostructures (Nb/Cu 41 Ni 59 bilayers) in dependence on the thickness of the ferromagnetic layer (Published in : A.S. Sidorenko, V.I. Zdravkov, J. Kehrle, R.Morari, E.Antropov, G. Obermeier, S. Gsell, M. Schreck, C. Muller, V.V. Ryazanov, S. Horn, R. Tidecks, L.R. Tagirov. Extinction and recovery of superconductivity by interference in superconductor/ferromagnet bilayers. In: Nanoscale Phenomena . Fundamentals and Applications,Ed. by H.Hahn, A.Sidorenko, I.Tiginyanu, Springer, 2009 p.1-10. Perspectives of applications: design of a new generation of superconducting spintronic devices - high frequency operating superconducting spin-switch for telecommunication and computers. (author)

Superconducting and normal state properties of carbon doped and neutron irradiated MgB2

International Nuclear Information System (INIS)

Wilke, R.H.T.; Samuely, P.; Szabo, P.; Holanova, Z.; Bud'ko, S.L.; Canfield, P.C.; Finnemore, D.K.

2007-01-01

Current research in MgB 2 focuses on the effects various types of perturbations have on the superconducting properties of this novel two-gap superconductor. In this article we summarize the effects of carbon doping and neutron irradiation in bulk MgB 2 . Low levels of carbon doping and light neutron irradiation result in significant enhancements in H c2 . At high fluences, where superconductivity is nearly fully suppressed, superconductivity can be restored through post exposure annealing. However, this results in a change in the interdependencies of the normal state and superconducting properties (ρ 0 , T c , H c2 ), with little or no enhancement in H c2

Superconductivity in the U(Th)-Y-Ba-Cu-O systems

International Nuclear Information System (INIS)

Qin Qizong; He Adi; Jia Weijie; Ma Lidun; Cheng Huansheng; Hua Zhongyi

1989-01-01

High T c superconductivity has been observed both resistively and magnetically in the new U(Th)-Y-Ba-Cu-O systems. The zero resistance temperature of the three samples with nominal composition of U 0.1 Y 1.1 Ba 0.8 Cu O 4-z , U 0.15 Y 1.05 Ba 0.8 Cu 4-z and Th 0.3 Y 0.8 Ba 0.8 Cu 4-z is 87K, 79K and 74K, respectively. The result of ac magnetic susceptibility measurement implies that the superconducting state is realized in the U-doped samples below 90K. The stoichimetry of the U-Y-Ba-Cu O superconductors has the aid of Rutherford backscattering and nuclear reaction 16 O(d, p) 17 O. The analytical results show that the 'real composition' of somples may be different from that of the nomial composition. The X ray diffraction analysis of the U-Y-Ba-Cu-O system shows that none of the peaks can be fitted to the uranium oxides and the other raw materiale structure, and its pattern may be attributed to new multiple phases with structure different from the known singlephase superconducting oxides

Study on niobium carbide dispersed superconducting tapes

Energy Technology Data Exchange (ETDEWEB)

Wada, H; Tachikawa, K [National Research Inst. for Metals, Tokyo (Japan); Oh' asa, M [Science Univ. of Tokyo (Japan)

1977-11-01

Niobium carbide (NbC) dispersed superconducting tapes have been fabricated by two metallurgical processes. In the first process, Ni-Nb-C alloys are directly arc melted and hot worked in air and the NbC phase is distributed in the form of fine discrete particles. In the second process, Ni-Nb and Ni-Nb-Cu alloys are arc melted, hot worked and subjected to solid-state carburization. NbC then precipitates along the grain boundaries, forming a network. The highest superconducting transition temperature attained is about 11 K. Taken together with the lattice parameter measurement, this indicates that NbC with a nearly perfect NaCl structure is formed in both processes. Measured values of the upper critical field, the critical current density and the volume fraction of the NbC phase are also discussed.

Thermodynamic Critical Field and Superconducting Fluctuation of Vortices for High Temperature Cuprate Superconductor: La-214

International Nuclear Information System (INIS)

Yung Moo Huh

2001-01-01

Thermodynamics has been studied systematically for the high temperature cuprate superconductor La 2-x Sr x CuO 4-δ , La-214, in the entire superconductive region from strongly underdoped to strongly overdoped regimes. Magnetization studies with H(parallel)c have been made in order to investigate the changes in free energy of the system as the number of carriers is reduced. Above the superconducting transition temperature, the normal-state magnetization exhibits a two-dimensional Heisenberg antiferromagnetic behavior. Below T c , magnetization data are thermodynamically reversible over large portions of the H-T plane, so the free energy is well defined in these regions. As the Sr concentration is varied over the wide range from 0.060 (strongly underdoped) to 0.234 (strongly overdoped), the free energy change goes through a maximum at the optimum doped in a manner similar to the T c0 vs. x curve. The density of states, N(0), remains nearly constant in the overdoped and optimum doped regimes, taking a broad maximum around x = 0.188, and then drops abruptly towards zero in the underdoped regime. The La 2-x Sr x CuO 4 (La-214) system displays the fluctuating vortex behavior with the characteristic of either 2D or 3D fluctuations as indicated by clearly identifiable crossing points T* close to T c . The dimensional character of the fluctuations depends on both applied magnetic fields and the density of charge carriers. The dimensional crossover from 2D to 3D occurs in the strongly underdoped regime when the c-axis coherence distance ζ c becomes comparable to the spacing between adjacent CuO 2 layers s at sufficiently high magnetic fields near H c2

Thermodynamic Critical Field and Superconducting Fluctuation of Vortices for High Temperature Cuprate Superconductor: La-214

International Nuclear Information System (INIS)

Finnemore, Douglas K.

2001-01-01

Thermodynamics has been studied systematically for the high temperature cuprate superconductor La 2-x Sr x CuO 4-δ , La-214, in the entire superconductive region from strongly underdoped to strongly overdoped regimes. Magnetization studies with H (parallel) c have been made in order to investigate the changes in free energy of the system as the number of carriers is reduced. Above the superconducting transition temperature, the normal-state magnetization exhibits a two-dimensional Heisenberg antiferromagnetic behavior. Below T c , magnetization data are thermodynamically reversible over large portions of the H-T plane, so the free energy is well defined in these regions. As the Sr concentration is varied over the wide range from 0.060 (strongly underdoped) to 0.234 (strongly overdoped), the free energy change goes through a maximum at the optimum doped in a manner similar to the T c0 vs. x curve. The density of states, N(0), remains nearly constant in the overdoped and optimum doped regimes, taking a broad maximum around x = 0.188, and then drops abruptly towards zero in the underdoped regime. The La 2-x Sr x CuO 4 (La-214) system displays the fluctuating vortex behavior with the characteristic of either 2D or 3D fluctuations as indicated by clearly identifiable crossing points T* close to T c . The dimensional character of the fluctuations depends on both applied magnetic fields and the density of charge carriers. The dimensional crossover from 2D to 3D occurs in the strongly underdoped regime when the c-axis coherence distance ξ c becomes comparable to the spacing between adjacent CuO 2 layers s at sufficiently high magnetic field near H c2

Proposal for an Accelerator R&D User Facility at Fermilab's Advanced Superconducting Test Accelerator (ASTA)

Energy Technology Data Exchange (ETDEWEB)

Church, M. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Edwards, H. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Harms, E. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Henderson, S. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Holmes, S. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Lumpkin, A. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Kephart, R. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Levedev, V. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Leibfritz, J. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Nagaitsev, S. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Piot, P. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Northern Illinois Univ., DeKalb, IL (United States); Prokop, C. [Northern Illinois Univ., DeKalb, IL (United States); Shiltsev, V. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Sun, Y. E. [Argonne National Lab. (ANL), Argonne, IL (United States); Valishev, A. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)

2013-10-01

Fermilab is the nation’s particle physics laboratory, supported by the DOE Office of High Energy Physics (OHEP). Fermilab is a world leader in accelerators, with a demonstrated track-record— spanning four decades—of excellence in accelerator science and technology. We describe the significant opportunity to complete, in a highly leveraged manner, a unique accelerator research facility that supports the broad strategic goals in accelerator science and technology within the OHEP. While the US accelerator-based HEP program is oriented toward the Intensity Frontier, which requires modern superconducting linear accelerators and advanced highintensity storage rings, there are no accelerator test facilities that support the accelerator science of the Intensity Frontier. Further, nearly all proposed future accelerators for Discovery Science will rely on superconducting radiofrequency (SRF) acceleration, yet there are no dedicated test facilities to study SRF capabilities for beam acceleration and manipulation in prototypic conditions. Finally, there are a wide range of experiments and research programs beyond particle physics that require the unique beam parameters that will only be available at Fermilab’s Advanced Superconducting Test Accelerator (ASTA). To address these needs we submit this proposal for an Accelerator R&D User Facility at ASTA. The ASTA program is based on the capability provided by an SRF linac (which provides electron beams from 50 MeV to nearly 1 GeV) and a small storage ring (with the ability to store either electrons or protons) to enable a broad range of beam-based experiments to study fundamental limitations to beam intensity and to develop transformative approaches to particle-beam generation, acceleration and manipulation which cannot be done elsewhere. It will also establish a unique resource for R&D towards Energy Frontier facilities and a test-bed for SRF accelerators and high brightness beam applications in support of the OHEP

Phases and structural characteristics of high Tc superconducting oxide in (Bi, Pb)-Sr-Ca-Cu-O system

International Nuclear Information System (INIS)

Chen, Zuyano; Li, Zhengrong; Qian, Yitai; Zhou, Quien; Cheng, Tingzhu

1989-01-01

The various phases, which are responsible for variant maximum d-value including 18.5 angstrom, 15.4 angstrom, 12.2 angstrom, 6.2 angstrom, 3.2 angstrom and possible 9.1 angstrom respectively, observed in high Tc superconducting complex oxide of (Bi,Pb)-Sr-Ca-Cu-O system are reported in this paper according to the result of X-ray diffraction on platelike crystals or crystallites synthesized under different preparation conditions. The phase of tetragonal system with c=3.21 angstrom, a=3.86 angstrom is possible parent structural unit and it is of great significance to the structure constitution of various phases with large lattice parameter c and structural characteristics of superconducting oxide. In view of the above a model of two-dimension stack-up which causes a stack in variant styles along c-axis and constitute various phases with different lattice parameter c is proposed and discussed

The shipping man adventures in ship finance

CERN Document Server

McCleery, Matthew

2013-01-01

When restless New York City hedge fund manager Robert Fairchild watches the Baltic Dry Cargo Index plunge 97%, registering an all-time high and a 25-year low within the span of just six months, he decides to buy a ship. Immediately fantasizing about naming a vessel after his wife, carrying a string of worry beads and being able to introduce himself as a "shipowner" at his upcoming college reunion, Fairchild immediately embarks on an odyssey into the most exclusive, glamorous and high stakes business in the world. From pirates off the coast of Somalia and on Wall Street to Greek and Norwegian shipping magnates, the education of Robert Fairchild is an expensive one. In the end, he loses his hedge fund, but he gains a life - as a Shipping Man. Part fast paced financial thriller, part ship finance text book, The Shipping Man is 310 pages of required reading for anyone with an interest in capital formation for shipping.

The superconducting proximity effect in epitaxial Al/Pb nanocomposites

International Nuclear Information System (INIS)

Wang, H; Vantomme, A; Temst, K; Picot, T; Houben, K; Moorkens, T; Van Haesendonck, C; Van Bael, M J; Grigg, J; Brown, S A; Biermans, E; Bals, S

2014-01-01

We have investigated the superconducting properties of Pb nanoparticles with a diameter ranging from 8 to 20 nm, synthesized by Pb + ion implantation in a crystalline Al matrix. A detailed structural characterization of the nanocomposites reveals the highly epitaxial relation between the Al crystalline matrix and the Pb nanoparticles. The Al/Pb nanocomposites display a single superconducting transition, with the critical temperature T c increasing with the Pb content. The dependence of T c on the Pb/Al volume ratio was compared with theoretical models of the superconducting proximity effect based on the bulk properties of Al and Pb. A very good correspondence with the strong-coupling proximity effect model was found, with an electron–phonon coupling constant in the Pb nanoparticles slightly reduced compared to bulk Pb. Our result differs from other studies on Pb nanoparticle based proximity systems where weak-coupling models were found to better describe the T c dependence. We infer that the high interface quality resulting from the ion implantation synthesis method is a determining factor for the superconducting properties. Critical field and critical current measurements support the high quality of the nanocomposite superconducting films. (paper)

Parallel critical magnetic fields of superconducting hyperthin films of vanadium and technetium

International Nuclear Information System (INIS)

Teplov, A.A.; Mikheeva, M.N.

1980-01-01

The nature of limiting parallel magnetic fields Hsub(c parallel) destroying a superconducting state in films of vanadium and technetium is found out. A dependence of Hsub(c parallel) on the thickness of films up to d approximately 60 A is studied. The |dHsub(c parallel)sup(2)/dT|sub(Tsub(c)) derivative, which increases in the region of large d with the increase of 1/d and achieves the maximum va;ue at d approximately 100 A, was determined, using the experimental data. For the most thin films this derivative tends to drop (the value of the derivative changes from 16 up to 20.00 kOe 2 /k and for technetium and from 4 up to 2100 kOe 2 /k for vanadium). Such stop at |dHsub(c11)sup(2)/ dT|sub(Tsub(c)) growth during the decrease of d is not explained in the framework of the theory taking into account only orbital effects. An account of the additional paramagnetic effect (spin effects) leads to a good agreement of the experiment with the theory in the whole range of thicknesses for vanadium. For technetium films in the d range <=110 A the value of Hsub(c parallel) exceeds several times Hsub(c parallel) calculated with provision of spin effects. For d approximately 80 A and d approximately 55 A this increase achieves the triple value. This effect is explained qualitatively by the spin-orbital scattering appearing with the increase of the atomic number

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

Critical region of a type II superconducting film near Hsub(c2): rational approximants

International Nuclear Information System (INIS)

Ruggeri, G.J.

1979-01-01

The high-temperature perturbative expansions for the thermal quantities of a type II superconducting film are extrapolated to the critical region near Hsub(c2) by means of new rational approximants of the Pade type. The new approximants are forced to reproduce the leading correction to the flux lattice contribution on the low-temperature side of the transition. Compared to those previously considered in the literature: (i) the mutual consistency of the approximants is improved; and (ii) they are nearer to the exact solution of the zero-dimensional Landau-Ginsburg model. (author)

Are nuclear ships environmentally safer than conventionally powered ships

International Nuclear Information System (INIS)

Bone, C.A.; Molgaard, C.A.; Helmkamp, J.C.; Golbeck, A.L.

1988-01-01

An epidemiologic analysis was conducted to determine if risk of hospitalization varied by age, ship type, or occupation between nuclear and conventional powered ship crews in the U.S. Navy. Study cohorts consisted of all male enlisted personnel who served exclusively aboard conventional or nuclear powered aircraft carriers and cruisers during the years 1975-1979; cases were those men hospitalized during this period (N = 48,242). Conventional ship personnel showed significantly elevated rates of injury and disease when compared to nuclear ship personnel. The largest relative risks by age occurred for conventional ship crewmen less than 30 years old. Seaman, logistics (supply), and healthcare personnel serving aboard conventional ships comprised the occupational groups exhibiting the highest hospitalization rate differentials. The results strongly suggest that nuclear ships provide a healthier, safer working and living environment than conventional ships

Superconductivity of divalent Chevrel phases at very high pressures

International Nuclear Information System (INIS)

Yao, Y.S.; Guertin, R.P.; Hinks, D.G.; Jorgensen, J.; Capone II, D.W.

1988-01-01

The electrical resistivity and the superconducting transition temperatures were examined for three representative divalent Chevrel phase systems, SnMo 6 S 8 , EuMo 6 S 8 , and BaMo 6 S 8 , as a function of hydrostatic pressure to 2 GPa and in quasihydrostatic pressures to 10 GPa. In all systems, T/sub c/ is depressed to 0 K for sufficiently large pressures. For the Sn- and Eu-based systems, both highly purified samples and samples with controlled oxygen content were used. In an oxygenated SnMo 6 S 8 sample (less than 3% O 2 substituted for the S atoms) the pressure threshold and maximum T/sub c/ are 40% lower than in the pure sample, but for P>3.5 GPa the T/sub c/-P phase diagrams nearly coincide, with T/sub c/ reaching zero at an extrapolated pressure of about 12 GPa. In pure EuMo 6 S 8 , superconductivity appears only above a threshold pressure of about 1 GPa and is depressed to 0 K above 4.5 GPa. In an oxygenated sample the maximum T/sub c/ and the threshold pressure are depressed, and above about 3.5 GPa the T/sub c/-P phase diagrams coincide, as in the Sn-based system, although T/sub c/ is then rapidly depressed to 0 K at about 4.5 GPa. In a highly purified BaMo 6 S 8 sample superconductivity appears above about 2 GPa and is depressed to 0 K at extrapolated pressures above 12 GPa. A full transition to the zero-resistance superconducting state is observed in BaMo 6 S 8 . The data are discussed in terms of a model linking the rhombohedral-to-triclinic structural transition, the superconducting transition temperature, and the role of pressure in suppressing the structural transition

Shipping

NARCIS (Netherlands)

Wijnolst, N.; Wergeland, T.

1996-01-01

Shipping is a multi-faceted industry which is rather complex to define from an academic point of view. This book attempts to grasp these complexities and provide the reader with an overview of the main topics and terminology in shipping. The book is based on material from our courses in shipping at

Microscopic Superconductivity and Room Temperature Electronics of High-Tc Cuprates

International Nuclear Information System (INIS)

Liu Fusui; Chen Wanfang

2008-01-01

This paper points out that the Landau criterion for macroscopic superfluidity of He II is only a criterion for microscopic superfluidity of 4 He, extends the Landau criterion to microscopic superconductivity in fermions (electron and hole) system and system with Cooper pairs without long-range phase coherence. This paper gives another three non-superconductive systems that are of microscopic superconductivity. This paper demonstrates that one application of microscopic superconductivity is to establish room temperature electronics of the high-T c cuprates

Unusual temperature evolution of superconductivity in LiFeAs

Energy Technology Data Exchange (ETDEWEB)

Nag, Pranab Kumar; Schlegel, Ronny; Baumann, Danny; Grafe, Hans-Joachim; Beck, Robert [Leibniz Institute for Solid State and Materials Research Dresden, IFW Dresden (Germany); Wurmehl, Sabine [Leibniz Institute for Solid State and Materials Research Dresden, IFW Dresden (Germany); Institute for Solid State Physics, TU Dresden (Germany); Buechner, Bernd [Leibniz Institute for Solid State and Materials Research Dresden, IFW Dresden (Germany); Institute for Solid State Physics, TU Dresden (Germany); Center for Transport and Devices, TU Dresden (Germany); Hess, Christian [Leibniz Institute for Solid State and Materials Research Dresden, IFW Dresden (Germany); Center for Transport and Devices, TU Dresden (Germany)

2016-07-01

We have performed temperature dependent scanning tunneling spectroscopy on an impurity-free surface area of a LiFeAs single crystal. Our data reveal a highly unusual temperature evolution of superconductivity: at T{sub c}{sup *}=18 K a partial superconducting gap opens, as is evidenced by subtle, yet clear features in the tunneling spectra, i.e. particle-hole symmetric coherence peaks and dip-hump structures. At T{sub c}=16 K, these features substantiate dramatically and become characteristic of full superconductivity. Remarkably, this is accompanied by an almost jump-like increase of the gap energy at T{sub c} to about 87% of its low-temperature gap value. The energy of the dip as measured by its distance to the coherence peak remains practically constant in the whole temperature regime T ≤ T{sub c}{sup *}. We compare these findings with established experimental and theoretical results.

Ship Detection in Optical Satellite Image Based on RX Method and PCAnet

Science.gov (United States)

Shao, Xiu; Li, Huali; Lin, Hui; Kang, Xudong; Lu, Ting

2017-12-01

In this paper, we present a novel method for ship detection in optical satellite image based on the ReedXiaoli (RX) method and the principal component analysis network (PCAnet). The proposed method consists of the following three steps. First, the spatially adjacent pixels in optical image are arranged into a vector, transforming the optical image into a 3D cube image. By taking this process, the contextual information of the spatially adjacent pixels can be integrated to magnify the discrimination between ship and background. Second, the RX anomaly detection method is adopted to preliminarily extract ship candidates from the produced 3D cube image. Finally, real ships are further confirmed among ship candidates by applying the PCAnet and the support vector machine (SVM). Specifically, the PCAnet is a simple deep learning network which is exploited to perform feature extraction, and the SVM is applied to achieve feature pooling and decision making. Experimental results demonstrate that our approach is effective in discriminating between ships and false alarms, and has a good ship detection performance.

Bulk Superconductivity and Disorder in Single Crystals of LaFePO

Energy Technology Data Exchange (ETDEWEB)

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

2010-02-15

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

Lateral restorable characteristics of the high-T{sub c} superconducting maglev vehicle above the permanent magnet guideway

Energy Technology Data Exchange (ETDEWEB)

Ma, G.T., E-mail: guangtma@gmail.co [Applied Superconductivity Laboratory, Southwest Jiaotong University, Mail Stop 152, Chengdu, Sichuan 610031 (China); Wang, J.S., E-mail: asclab@asclab.c [Applied Superconductivity Laboratory, Southwest Jiaotong University, Mail Stop 152, Chengdu, Sichuan 610031 (China); Lin, Q.X.; Liu, M.X.; Deng, Z.G.; Li, X.C.; Liu, H.F.; Zheng, J.; Wang, S.Y. [Applied Superconductivity Laboratory, Southwest Jiaotong University, Mail Stop 152, Chengdu, Sichuan 610031 (China)

2009-11-01

The lateral restorable characteristics of a translational symmetry high-T{sub c} superconducting maglev system are investigated by measuring its resonant frequency (f{sub RF}) after a lateral displacement. The difference between whether this lateral displacement is restorable, meaning elastic or inelastic, is determined by whether or not the maglev body returns to its original position after a lateral displacement. The maximum restorable lateral displacement (delta{sub MRLD}) is determined by the sudden change of the f{sub RF} vs. the maximum lateral displacement (delta{sub MLD}) curve. The f{sub RF} of the high-T{sub c} superconducting maglev system with different field-cooling height (FCH) and working height (WH) was obtained from the frequency domain vibration curve which was measured by a vibration measurement system. The results showed that, the delta{sub MRLD} was reduced when the WH was decreased. The maximum restorable guidance force (F{sub MRGF}) was found to not always increase with the lowering of the WH for the same FCH. The lateral restorable stiffness (k{sub LRS}) was always enhanced with the decrease of the WH. The decrease of the delta{sub MRLD} with the WH is interpreted by the fact that, the tangential field component (DELTAH) across the surface of the high-T{sub c} superconductor (HTSC) is easier to exceed the J{sub c}lambda value (J{sub c} is the critical current density and lambda is the London penetration depth) when the WH is lowered, and this makes the trapped flux lines become more susceptible in escaping its pinning sites.

On the Global Ship Hull Bending Energy in Ship Collisions

DEFF Research Database (Denmark)

Pedersen, Preben Terndrup; Li, Y.

2004-01-01

During ship collisions part of the kinetic energy of the involved vessels prior to contact is absorbed as energy dissipated by crushing of the hull structures, by friction and by elastic energy. The purpose of this report is to present an estimate of the elastic energy that can be stored in elastic...... hull vibrations during a ship collision. When a ship side is strengthened in order to improve the crashworthiness it has been argued in the scientific literature that a non trivial part of the energy released for structural deformation during the collision can be absorbed as elastic energy in global...... ship hull vibrations, such that with strong ship sides less energy has to be spent in crushing of the striking ship bow and/or the struck ship side. In normal ship-ship collision analyses both the striking and struck ship are usually considered as rigid bodies where structural crushing is confined...

Strong-coupling superconductivity in the two-dimensional t-J model supplemented by a hole-phonon interaction

International Nuclear Information System (INIS)

Sherman, A.; Schreiber, M.

1995-01-01

We use the Eliashberg formalism for calculating T c in a model of cuprate perovskites with pairing mediated by both magnons and apex-oxygen vibrations. The influence of strong correlations on the energy spectrum is taken into account in the spin-wave approximation. It is shown that the hole-magnon interaction alone cannot yield high T c . But together with a moderate hole-phonon interaction it does lead to d-wave superconductivity at temperatures and hole concentrations observed in cuprates. High T c are connected with a large density of states due to extended Van Hove singularities, a conformity of the two interactions for the d symmetry, and high phonon frequencies

A new approach to MgB2 superconducting magnet fabrication

International Nuclear Information System (INIS)

Miyazoe, A; Ando, T; Wada, H; Abe, H; Hirota, N; Sekino, M

2008-01-01

Fabrication of MgB 2 -based superconducting magnets has been attempted by a new approach using film coated on symmetric tubes. Superconducting MgB 2 films have been prepared on iron substrates by electroplating in molten electrolytes. The critical current (I c ) of the MgB 2 electroplating films at 4.2 K and at self-field was 15 A on the basis of 1 μV/cm of I c criterion. A model calculation has shown that MgB 2 -based superconducting magnets based on MgB 2 electroplating films have the potential to generate magnetic fields over 0.5 T

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).

A study on metastable superconducting magnets

International Nuclear Information System (INIS)

Koyama, Kenichi

1976-01-01

It is important to construct superconducting magnets as cheap as possible. One of the methods to achieve such a purpose is to save the superconducting material and operate the magnets at a high current density. Therefore it is useful to investigate the requirements for the operation of metastable superconducting magnets which can work at a current higher than the recovery current. Using the theory of flux jump, we introduce a ''stable current'' below which no flux jump can occur. On a rough approximation, it is given by I sub(s) =√A P sub(i) H sub(e) T sub(o) f(x)/rho where A : cross-section of the composite conductor. P sub(i) : total perimeter of all the superconducting cores. h sub(e) : effective heat transfer coefficient to the liquid helium through the stabilizer. T sub(o) : a characteristic temperature of the superconducting cores. f(x) : a characteristic function for the relative core radius x. rho : effective resistivity of the composite. Then it is shown that superconducting magnets can operate without unexpected normal transitions in the region enclosed by the two curves of I sub(s) and I sub(c). Next, we discuss the characteristics of our saddle shaped superconducting magnet for an one-KW MHD generator. We found that, 1) the magnet does safely operate in the metastable state; 2) the characteristics of the magnet are consistent with our theoretical results. (auth.)

Superconducting A.C. generators. Some recent experimental investigations

International Nuclear Information System (INIS)

Ross, J.S.H.; Smith, D.A.

1978-01-01

Experimental work is reported which has been carried out in the past three years aimed at evaluating the materials and the design features applicable to large superconducting generators. Two main topics are considered: (1) A detailed and comprehensive investigation into the physical properties of a six tonne forging in austenitic stainless steel AISI 316LN. (2) The design of a system to transfer helium onto and from a rotating shaft. (UK)

Vortex properties of mesoscopic superconducting samples

Energy Technology Data Exchange (ETDEWEB)

Cabral, Leonardo R.E. [Laboratorio de Supercondutividade e Materiais Avancados, Departamento de Fisica, Universidade Federal de Pernambuco, Recife 50670-901 (Brazil); Barba-Ortega, J. [Grupo de Fi' sica de Nuevos Materiales, Departamento de Fisica, Universidad Nacional de Colombia, Bogota (Colombia); Souza Silva, C.C. de [Laboratorio de Supercondutividade e Materiais Avancados, Departamento de Fisica, Universidade Federal de Pernambuco, Recife 50670-901 (Brazil); Albino Aguiar, J., E-mail: albino@df.ufpe.b [Laboratorio de Supercondutividade e Materiais Avancados, Departamento de Fisica, Universidade Federal de Pernambuco, Recife 50670-901 (Brazil)

2010-10-01

In this work we investigated theoretically the vortex properties of mesoscopic samples of different geometries, submitted to an external magnetic field. We use both London and Ginzburg-Landau theories and also solve the non-linear Time Dependent Ginzburg-Landau equations to obtain vortex configurations, equilibrium states and the spatial distribution of the superconducting electron density in a mesoscopic superconducting triangle and long prisms with square cross-section. For a mesoscopic triangle with the magnetic field applied perpendicularly to sample plane the vortex configurations were obtained by using Langevin dynamics simulations. In most of the configurations the vortices sit close to the corners, presenting twofold or three-fold symmetry. A study of different meta-stable configurations with same number of vortices is also presented. Next, by taking into account de Gennes boundary conditions via the extrapolation length, b, we study the properties of a mesoscopic superconducting square surrounded by different metallic materials and in the presence of an external magnetic field applied perpendicularly to the square surface. It is determined the b-limit for the occurrence of a single vortex in a mesoscopic square of area d{sup 2}, for 4{xi}(0){<=}d{<=}10{xi}(0).

Search for the rare decays J /ψ →D0e+e-+c .c . and ψ (3686 )→D0e+e-+c .c .

Science.gov (United States)

Ablikim, M.; Achasov, M. N.; Ahmed, S.; Albrecht, M.; Amoroso, A.; An, F. F.; An, Q.; Bai, J. Z.; Bakina, O.; Baldini Ferroli, R.; Ban, Y.; Bennett, D. W.; Bennett, J. V.; Berger, N.; Bertani, M.; Bettoni, D.; Bian, J. M.; Bianchi, F.; Boger, E.; Boyko, I.; Briere, R. A.; Cai, H.; Cai, X.; Cakir, O.; Calcaterra, A.; Cao, G. F.; Cetin, S. A.; Chai, J.; Chang, J. F.; Chelkov, G.; Chen, G.; Chen, H. S.; Chen, J. C.; Chen, M. L.; Chen, S. J.; Chen, X. R.; Chen, Y. B.; Chu, X. K.; Cibinetto, G.; Dai, H. L.; Dai, J. P.; Dbeyssi, A.; Dedovich, D.; Deng, Z. Y.; Denig, A.; Denysenko, I.; Destefanis, M.; de Mori, F.; Ding, Y.; Dong, C.; Dong, J.; Dong, L. Y.; Dong, M. Y.; Dorjkhaidav, O.; Dou, Z. L.; Du, S. X.; Duan, P. F.; Fang, J.; Fang, S. S.; Fang, X.; Fang, Y.; Farinelli, R.; Fava, L.; Fegan, S.; Feldbauer, F.; Felici, G.; Feng, C. Q.; Fioravanti, E.; Fritsch, M.; Fu, C. D.; Gao, Q.; Gao, X. L.; Gao, Y.; Gao, Y. G.; Gao, Z.; Garzia, I.; Goetzen, K.; Gong, L.; Gong, W. X.; Gradl, W.; Greco, M.; Gu, M. H.; Gu, S.; Gu, Y. T.; Guo, A. Q.; Guo, L. B.; Guo, R. P.; Guo, Y. P.; Haddadi, Z.; Hafner, A.; Han, S.; Hao, X. Q.; Harris, F. A.; He, K. L.; He, X. Q.; Heinsius, F. H.; Held, T.; Heng, Y. K.; Holtmann, T.; Hou, Z. L.; Hu, C.; Hu, H. M.; Hu, T.; Hu, Y.; Huang, G. S.; Huang, J. S.; Huang, X. T.; Huang, X. Z.; Huang, Z. L.; Hussain, T.; Ikegami Andersson, W.; Ji, Q.; Ji, Q. P.; Ji, X. B.; Ji, X. L.; Jiang, X. S.; Jiang, X. Y.; Jiao, J. B.; Jiao, Z.; Jin, D. P.; Jin, S.; Johansson, T.; Julin, A.; Kalantar-Nayestanaki, N.; Kang, X. L.; Kang, X. S.; Kavatsyuk, M.; Ke, B. C.; Khan, T.; Kiese, P.; Kliemt, R.; Kloss, B.; Koch, L.; Kolcu, O. B.; Kopf, B.; Kornicer, M.; Kuemmel, M.; Kuhlmann, M.; Kupsc, A.; Kühn, W.; Lange, J. S.; Lara, M.; Larin, P.; Lavezzi, L.; Leithoff, H.; Leng, C.; Li, C.; Li, Cheng; Li, D. M.; Li, F.; Li, F. Y.; Li, G.; Li, H. B.; Li, H. J.; Li, J. C.; Li, Jin; Li, Kang; Li, Ke; Li, Lei; Li, P. L.; Li, P. R.; Li, Q. Y.; Li, T.; Li, W. D.; Li, W. G.; Li, X. L.; Li, X. N.; Li, X. Q.; Li, Z. B.; Liang, H.; Liang, Y. F.; Liang, Y. T.; Liao, G. R.; Lin, D. X.; Liu, B.; Liu, B. J.; Liu, C. X.; Liu, D.; Liu, F. H.; Liu, Fang; Liu, Feng; Liu, H. B.; Liu, H. M.; Liu, Huanhuan; Liu, Huihui; Liu, J. B.; Liu, J. P.; Liu, J. Y.; Liu, K.; Liu, K. Y.; Liu, Ke; Liu, L. D.; Liu, P. L.; Liu, Q.; Liu, S. B.; Liu, X.; Liu, Y. B.; Liu, Y. Y.; Liu, Z. A.; Liu, Zhiqing; Long, Y. F.; Lou, X. C.; Lu, H. J.; Lu, J. G.; Lu, Y.; Lu, Y. P.; Luo, C. L.; Luo, M. X.; Luo, T.; Luo, X. L.; Lyu, X. R.; Ma, F. C.; Ma, H. L.; Ma, L. L.; Ma, M. M.; Ma, Q. M.; Ma, T.; Ma, X. N.; Ma, X. Y.; Ma, Y. M.; Maas, F. E.; Maggiora, M.; Malik, Q. A.; Mao, Y. J.; Mao, Z. P.; Marcello, S.; Messchendorp, J. G.; Mezzadri, G.; Min, J.; Min, T. J.; Mitchell, R. E.; Mo, X. H.; Mo, Y. J.; Morales Morales, C.; Morello, G.; Muchnoi, N. Yu.; Muramatsu, H.; Musiol, P.; Mustafa, A.; Nefedov, Y.; Nerling, F.; Nikolaev, I. B.; Ning, Z.; Nisar, S.; Niu, S. L.; Niu, X. Y.; Olsen, S. L.; Ouyang, Q.; Pacetti, S.; Pan, Y.; Papenbrock, M.; Patteri, P.; Pelizaeus, M.; Pellegrino, J.; Peng, H. P.; Peters, K.; Pettersson, J.; Ping, J. L.; Ping, R. G.; Poling, R.; Prasad, V.; Qi, H. R.; Qi, M.; Qian, S.; Qiao, C. F.; Qin, J. J.; Qin, N.; Qin, X. S.; Qin, Z. H.; Qiu, J. F.; Rashid, K. H.; Redmer, C. F.; Richter, M.; Ripka, M.; Rong, G.; Rosner, Ch.; Ruan, X. D.; Sarantsev, A.; Savrié, M.; Schnier, C.; Schoenning, K.; Shan, W.; Shao, M.; Shen, C. P.; Shen, P. X.; Shen, X. Y.; Sheng, H. Y.; Song, J. J.; Song, W. M.; Song, X. Y.; Sosio, S.; Sowa, C.; Spataro, S.; Sun, G. X.; Sun, J. F.; Sun, S. S.; Sun, X. H.; Sun, Y. J.; Sun, Y. K.; Sun, Y. Z.; Sun, Z. J.; Sun, Z. T.; Tang, C. J.; Tang, G. Y.; Tang, X.; Tapan, I.; Tiemens, M.; Tsednee, B. T.; Uman, I.; Varner, G. S.; Wang, B.; Wang, B. L.; Wang, D.; Wang, D. Y.; Wang, Dan; Wang, K.; Wang, L. L.; Wang, L. S.; Wang, M.; Wang, P.; Wang, P. L.; Wang, W. P.; Wang, X. F.; Wang, Y.; Wang, Y. D.; Wang, Y. F.; Wang, Y. Q.; Wang, Z.; Wang, Z. G.; Wang, Z. H.; Wang, Z. Y.; Wang, Zongyuan; Weber, T.; Wei, D. H.; Wei, J. H.; Weidenkaff, P.; Wen, S. P.; Wiedner, U.; Wolke, M.; Wu, L. H.; Wu, L. J.; Wu, Z.; Xia, L.; Xia, Y.; Xiao, D.; Xiao, H.; Xiao, Y. J.; Xiao, Z. J.; Xie, Y. G.; Xie, Y. H.; Xiong, X. A.; Xiu, Q. L.; Xu, G. F.; Xu, J. J.; Xu, L.; Xu, Q. J.; Xu, Q. N.; Xu, X. P.; Yan, L.; Yan, W. B.; Yan, W. C.; Yan, Y. H.; Yang, H. J.; Yang, H. X.; Yang, L.; Yang, Y. H.; Yang, Y. X.; Ye, M.; Ye, M. H.; Yin, J. H.; You, Z. Y.; Yu, B. X.; Yu, C. X.; Yu, J. S.; Yuan, C. Z.; Yuan, Y.; Yuncu, A.; Zafar, A. A.; Zeng, Y.; Zeng, Z.; Zhang, B. X.; Zhang, B. Y.; Zhang, C. C.; Zhang, D. H.; Zhang, H. H.; Zhang, H. Y.; Zhang, J.; Zhang, J. L.; Zhang, J. Q.; Zhang, J. W.; Zhang, J. Y.; Zhang, J. Z.; Zhang, K.; Zhang, L.; Zhang, S. Q.; Zhang, X. Y.; Zhang, Y. H.; Zhang, Y. T.; Zhang, Yang; Zhang, Yao; Zhang, Yu; Zhang, Z. H.; Zhang, Z. P.; Zhang, Z. Y.; Zhao, G.; Zhao, J. W.; Zhao, J. Y.; Zhao, J. Z.; Zhao, Lei; Zhao, Ling; Zhao, M. G.; Zhao, Q.; Zhao, S. J.; Zhao, T. C.; Zhao, Y. B.; Zhao, Z. G.; Zhemchugov, A.; Zheng, B.; Zheng, J. P.; Zheng, W. J.; Zheng, Y. H.; Zhong, B.; Zhou, L.; Zhou, X.; Zhou, X. K.; Zhou, X. R.; Zhou, X. Y.; Zhou, Y. X.; Zhu, K.; Zhu, K. J.; Zhu, S.; Zhu, S. H.; Zhu, X. L.; Zhu, Y. C.; Zhu, Y. S.; Zhu, Z. A.; Zhuang, J.; Zotti, L.; Zou, B. S.; Zou, J. H.; Besiii Collaboration

2017-12-01

Using the data samples of (1310.6 ±7.2 )×106 J /ψ events and (448.1 ±2.9 )×106 ψ (3686 ) events collected with the BESIII detector, we search for the rare decays J /ψ →D0e+e-+c .c . and ψ (3686 )→D0e+e-+c .c . No significant signals are observed and the corresponding upper limits on the branching fractions at the 90% confidence level are determined to be B (J /ψ →D0e+e-+c .c .)<8.5 ×10-8 and B (ψ (3686 )→D0e+e-+c .c .)<1.4 ×10-7 , respectively. Our limit on B (J /ψ →D0e+e-+c .c .) is more stringent by 2 orders of magnitude than the previous results, and B (ψ (3686 )→D0e+e-+c .c .) is measured for the first time.

Magnetism and superconductivity in Ru{sub 1-x}Sr{sub 2}RECu{sub 2+x}O{sub 8-d} (RE=Gd, Eu) and RuSr{sub 2}Gd{sub 1-y}Ce{sub y}Cu{sub 2}O{sub 8} compounds

Energy Technology Data Exchange (ETDEWEB)

Klamut, P.W. [Dept. of Physics, Northern Illinois Univ., DeKalb, IL (United States)]|[Inst. of Low Temperature and Structure Research of Polish Academy of Sciences, Wroclaw (Poland); Dabrowski, B.; Mini, S.M.; Kolesnik, S.; Maxwell, M.; Mais, J. [Dept. of Physics, Northern Illinois Univ., DeKalb, IL (United States); Shengelaya, A.; Keller, H. [Physik-Inst., Univ. Zuerich, Zuerich (Switzerland); Khazanov, R. [Physik-Inst., Univ. Zuerich, Zuerich (Switzerland)]|[Lab. for Muon-Spin Spectroscopy, Paul Scherrer Inst., Villigen PSI (Switzerland); Savic, I. [Physik-Inst., Univ. Zuerich, Zuerich (Switzerland)]|[Faculty of Physics, Univ. of Belgrade, Belgrade (Yugoslavia); Sulkowski, C.; Wlosewicz, D.; Matusiak, M. [Inst. of Low Temperature and Structure Research of Polish Academy of Sciences, Wroclaw (Poland); Wisniewski, A.; Puzniak, R.; Fita, I. [Inst. of Physics of Polish Academy of Sciences, Warszawa (Poland)

2002-07-01

We discuss the properties of new superconducting compositions of ruthenocuprates Ru{sub 1-x}Sr{sub 2}RECu{sub 2+x}O{sub 8-d} (RE=Gd, Eu) that were synthesized at 600 atm. of oxygen at 1080 C. By changing ratio between the Ru and Cu, the temperature of superconducting transition (T{sub C}) raises up to T{sub C}{sup max} = 72 K for x=0.3, 0.4. The hole doping achieved along the series increases with Cu{yields}Ru substitution. For x {ne} 0, T{sub C} can be subsequently tuned between T{sub C}{sup max} and 0 K by changing oxygen content in the compounds. The magnetic characteristics of the RE=Gd and Eu based compounds are interpreted as indicative of constrained dimensionality of the superconducting phase. Muon spin rotation experiments reveal the presence of the magnetic transitions at low temperatures (T{sub m}=14-2 K for x=0.1-0.4) that can originate in the response of Ru/Cu sublattice. RuSr{sub 2}Gd{sub 1-y}Ce{sub 1-y}Cu{sub 2}O{sub 8} (0 {<=} y {<=} 0.1) compounds show the simultaneous increase of T{sub N} and decrease of T{sub C} with y. The effect should be explained by the electron doping that occurs with Ce{yields}Gd substitution. Properties of these two series allow us to propose phase diagram for 1212-type ruthenocuprates that links their properties to the hole doping achieved in the systems. Non-superconducting single-phase RuSr{sub 2}GdCu{sub 2}O{sub 8} and RuSr{sub 2}EuCu{sub 2}O{sub 8} are reported and discussed in the context of the properties of substituted compounds. (orig.)

On the superconductivity of vanadium based alloys

International Nuclear Information System (INIS)

Brouers, F.; Rest, J.V. der

1985-01-01

We have computed the electron density of States of solid solutions of vanadium based transition metal alloys V 90 X 10 by using the tight-binding recursion method for degenerate d-bands in order to calculte the alloy superconducting transition temperature with the McMillan formula. As observed experimentally for X on the left hand side of V in the periodic table one obtains an increase of T c while for X on the right hand side of V the critical temperature decreases. The detailed comparison with experiments indicate that when the bandwidths of the two constituents are different, one cannot neglect the variation of the electron-phonon interactions. (author) [pt

MICROSTRUCTURE OF SUPERCONDUCTING MGB(2).

Energy Technology Data Exchange (ETDEWEB)

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

2001-07-12

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

Two-particle self-consistent approach to unconventional superconductivity

Energy Technology Data Exchange (ETDEWEB)

Otsuki, Junya [Department of Physics, Tohoku University, Sendai (Japan); Theoretische Physik III, Zentrum fuer Elektronische Korrelationen und Magnetismus, Universitaet Augsburg (Germany)

2013-07-01

A non-perturbative approach to unconventional superconductivity is developed based on the idea of the two-particle self-consistent (TPSC) theory. An exact sum-rule which the momentum-dependent pairing susceptibility satisfies is derived. Effective pairing interactions between quasiparticles are determined so that an approximate susceptibility should fulfill this sum-rule, in which fluctuations belonging to different symmetries mix at finite momentum. The mixing leads to a suppression of the d{sub x{sup 2}-y{sup 2}} pairing close to the half-filling, resulting in a maximum of T{sub c} away from half-filling.

Critical current enhancement driven by suppression of superconducting fluctuation in ion-gated ultrathin FeSe

Science.gov (United States)

Harada, T.; Shiogai, J.; Miyakawa, T.; Nojima, T.; Tsukazaki, A.

2018-05-01

The framework of phase transition, such as superconducting transition, occasionally depends on the dimensionality of materials. Superconductivity is often weakened in the experimental conditions of two-dimensional thin films due to the fragile superconducting state against defects and interfacial effects. In contrast to this general trend, superconductivity in the thin limit of FeSe exhibits an opposite trend, such as an increase in critical temperature (T c) and the superconducting gap exceeding the bulk values; however, the dominant mechanism is still under debate. Here, we measured thickness-dependent electrical transport properties of the ion-gated FeSe thin films to evaluate the superconducting critical current (I c) in the ultrathin FeSe. Upon systematically decreasing the FeSe thickness by the electrochemical etching technique in the Hall bar-shaped electric double-layer transistors, we observed a dramatic enhancement of I c reaching about 10 mA and corresponding to about 107 A cm‑2 in the thinnest condition. By analyzing the transition behavior, we clarify that the suppressed superconducting fluctuation is one of the origins of the large I c in the ion-gated ultrathin FeSe films. These results indicate the existence of a robust superconducting state possibly with dense Cooper pairs at the thin limit of FeSe.

Effect of pressure on the bandstructure and superconductivity in lutetium

International Nuclear Information System (INIS)

Asokamani, R.; Natarajan, S.; Rajagopalan, M.; Sundararajan, V.; Suvasini, M.B.; Iyakutti, K.

1984-08-01

The detailed bandstructure and superconducting behaviour of lutetium at 230 kbar pressure is reported here. The electronic contribution eta to the electron-phonon mass enhancement lambda is studied within the rigid muffin-tin (RMT) approximation. The pd and df matrix elements are expressed in terms of 'd' bandwidth, Fermi energy and muffin-tin zero. The variations of Grueneisen parameter and Debye temperature with pressure are studied and applied in the calculation of Tsub(c). The calculated Tsub(c) value agrees fairly well with the experimental value. The changes in the conduction bandwidth and the electronic specific heat coefficient with pressure are found to be in agreement with theoretical prediction. (author)

Superconductivity

International Nuclear Information System (INIS)

Kakani, S.L.; Kakani, Shubhra

2007-01-01

The monograph provides readable introduction to the basics of superconductivity for beginners and experimentalists. For theorists, the monograph provides nice and brief description of the broad spectrum of experimental properties, theoretical concepts with all details, which theorists should learn, and provides a sound basis for students interested in studying superconducting theory at the microscopic level. Special chapter on the theory of high-temperature superconductivity in cuprates is devoted

Effects of post-annealing and cobalt co-doping on superconducting properties of (Ca,Pr)Fe{sub 2}As{sub 2} single crystals

Energy Technology Data Exchange (ETDEWEB)

Okada, T., E-mail: 8781303601@mail.ecc.u-tokyo.ac.jp; Ogino, H.; Yakita, H.; Yamamoto, A.; Kishio, K.; Shimoyama, J.

2014-10-15

Highlights: • Post-annealing at 400 °C killed superconductivity for Co-free sample. • Pr,Co co-doped samples maintained superconductivity even after annealing. • Two-step superconducting transition was observed via magnetization measurement. • Bulk superconductivity of low-T{sub c} component was confirmed. • Superconducting volume fraction of high-T{sub c} component was always small. - Abstract: In order to clarify the origin of anomalous superconductivity in (Ca,RE)Fe{sub 2}As{sub 2} system, Pr doped and Pr,Co co-doped CaFe{sub 2}As{sub 2} single crystals were grown by the FeAs flux method. These samples showed two-step superconducting transition with T{sub c1} = 25–42 K, and T{sub c2} < 16 K, suggesting that (Ca,RE)Fe{sub 2}As{sub 2} system has two superconducting components. Post-annealing performed for these crystals in evacuated quartz ampoules at various temperatures revealed that post-annealing at ∼400 °C increased the c-axis length for all samples. This indicates that as-grown crystals have a certain level of strain, which is released by post-annealing at ∼400 °C. Superconducting properties also changed dramatically by post-annealing. After annealing at 400 °C, some of the co-doped samples showed large superconducting volume fraction corresponding to the perfect diamagnetism below T{sub c2} and high J{sub c} values of 10{sup 4}–10{sup 5} A cm{sup −2} at 2 K in low field, indicating the bulk superconductivity of (Ca,RE)Fe{sub 2}As{sub 2} phase occurred below T{sub c2}. On the contrary, the superconducting volume fraction above T{sub c2} was always very small, suggesting that 40 K-class superconductivity observed in this system is originating in the local superconductivity in the crystal.

Effect of anharmonicity and Debye-Waller factor on the superconductivity of PdHsub(x) and PdDsub(x)

International Nuclear Information System (INIS)

Griessen, R.; Groot, D.G. de

1983-01-01

On the basis of existing superconducting tunnelling, neutron scattering, electrical resistivity and Raman scattering data and new thermal expansion, elastic moduli and point-contact spectroscopy data it is concluded that the anharmonicity of the proton (deuteron)-palladium potential is such that Msub(H)#betta#sub(H) 2 /(Msub(D)#betta#sub(D) 2 ) = 1.12 +- 0.05 Msub(H(D)) is the mass and #betta#sub(H(D)) the frequency of the vibration of hydrogen (deuterium). This anharmonicity is approximately 2 times too weak to reproduce the observed inverse isotope effect in the superconducting transition temperature of concentrated PdHsub(x) and PdDsub(x) alloys. Within a pseudopotential formalism it is shown that the Debye-Waller factor arising from the large zero-point amplitude of the interstitial hydrogen (deuterium) leads to a contribution to the inverse isotope effect in Tsub(c) which is as large as that of anharmonicity alone. (Auth.)

Are we getting to the point of understanding high-temperature superconductivity?

International Nuclear Information System (INIS)

Huebener, R.P.; Tsuei, C.C.; Newns, D.M.

1994-01-01

The model elaborated by van Hove allows a coherent explanation of various anomalies observed with the phenomenon of high-T c superconductivity, including the cause of T c reaching such a high value, or the materials behaving like marginal Fermi liquids. However, there remain other enigma to be solved before it will be possible to fully explain and understand high-T c superconductivity. (DG) [de

On the global ship hull bending energy in ship collisions

DEFF Research Database (Denmark)

Pedersen, Preben Terndrup; Li, Yujie

2009-01-01

During ship collisions part of the kinetic energy of the involved vessels immediately prior to contact is absorbed as energy dissipated by crushing of the hull structures, by friction and by elastic energy. The purpose of this report is to present an estimate of the elastic energy that can...... be stored in elastic hull vibrations during a ship collision. When a ship side is strengthened in order to improve the crashworthiness it has been argued in the scientific literature that a non-trivial part of the energy released for structural deformation during the collision can be absorbed as elastic...... energy in global ship hull vibrations, such that with strong ship sides less energy has to be spent in crushing of the striking ship bow and/or the struck ship side. In normal ship–ship collision analyses both the striking and struck ship are usually considered as rigid bodies where structural crushing...

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

Nonlinearity in superconductivity and Josephson junctions

International Nuclear Information System (INIS)

Lazarides, N.

1995-01-01

Within the framework of the Bardeen, Cooper and Schrieffers (BCS) theory, the influence of anisotropy on superconducting states are investigated. Crystal anisotropy exists in un-conventional low temperature superconductors as e.g. U 1-x Th x Be 13 and in high temperature superconductors. Starting from a phenomenological pairing interaction of the electrons or holes, the BCS approach is used to derive a set of coupled nonlinear algebraic equations for the momentum dependent gap parameter. The emphasis is put on bifurcation phenomena between s-, d-wave and mixed s- and d-wave symmetry and the influence on measurable quantities as the electron specific heat, spin susceptibility and Josephson tunnelling. Pitch-fork and perturbed pitch-fork bifurcations have been found separating s- and d-wave superconducting states from mixed s- and d-wave states. The additional superconducting states give rise to jumps in the electron specific heat below the transition temperature. These jumps are rounded in the case of perturbed pitch-fork bifurcations. An experiment to measure the sign of the interlayer interaction using dc SQUIDS is suggested. The Ambegaokar-Baratoff formalism has been used for calculating the quasiparticle current and the two phase coherent tunnelling currents in a Josephson junction made of anisotropic superconductors. It is shown that anisotropy can lead to a reduction in the product of the normal resistance and the critical current. For low voltages across the junction the usual resistively shunted Josephson model can be used. Finally, bunching in long circular Josephson junctions and suppression of chaos in point junctions have been investigated. (au) 113 refs

Characteristic study of high-T{sub c} superconducting maglev under side-loading

Energy Technology Data Exchange (ETDEWEB)

Wang Wei [Applied Superconductivity Laboratory, M/S 152, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China)], E-mail: frank.weiwang@gmail.com; Wang Jiasu [Applied Superconductivity Laboratory, M/S 152, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China)], E-mail: asclab@asclab.cn; Liu Wei; Zheng Jun; Lin Qunxu; Pan Siting; Deng Zigang; Ma Guangtong; Wang Suyu [Applied Superconductivity Laboratory, M/S 152, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China)

2009-02-15

In practical application of High-T{sub c} Superconducting (HTS) maglev, slant is an observable defect. It was caused by constantly one side on and off the vehicle by passengers. So far, this phenomenon has not been reported yet. In order to understand its influence on the stability of the HTS maglev, we experimentally studied the dynamic characteristic and slant effect of HTS maglev under center-load and side-load. It was found that load destabilizes the vehicle, and the side-load can obviously slant the vehicle body. In the end, the pre-load method was proposed to enhance the dynamic stability and suppress the slant, which proved to be considerably effective. These results are critical in practical running of HTS maglev.

Crystal growth of YFe{sub 2}Ge{sub 2} and the dependence of its superconducting properties on sample preparation

Energy Technology Data Exchange (ETDEWEB)

Chen, Jiasheng; Semeniuk, Konstantin; Reiss, Pascal; Brown, Philip; Grosche, Malte [Cavendish Lab., Cambridge (United Kingdom); Feng, Zhuo [London Centre of Nanotechnology, UCL, London (United Kingdom); Lampronti, Giulio [Cambridge Univ., Dept. of Earth Sciences, Cambridge (United Kingdom)

2016-07-01

The d-electron system YFe{sub 2}Ge{sub 2} exhibits an unusually high Sommerfeld ratio of specific heat capacity of C/T ∝ 100 mJ/(molK{sup 2}), signaling strong electronic correlations. Evidence of superconductivity has been reported in polycrystals and in flux-grown single crystals with residual resistance ratios (RRR) of the order of 50, but these samples show no thermodynamic signatures of a bulk superconducting transition. We find that by combining (i) a prereaction of YFe{sub 2}, (ii) careful control of nominal composition, and (iii) subsequent annealing procedures, the polycrystalline YFe{sub 2}Ge{sub 2} samples grown using a radio-frequency (RF) induction furnace can reach RRR values ∝ 200 with resistive superconducting transitions temperatures of around 1.85 K. This new generation of sample displays clear heat capacity anomalies as well as nearly 100% diamagnetic screening, confirming the bulk nature of its superconductivity. We present details of the sample preparation and characterization and discuss the correlation between nominal composition and superconductivity.

Superconductivity: actual stage forcasting and subsidies for national policy

International Nuclear Information System (INIS)

Morato, S.P.

1987-01-01

An overview on the situation of metallic superconductors, their applications and market, and a brief history about the superconductivity at high T c (new ceramic superconductors), describing the actual level of research and development in the world and national plans are presented. Some comments about incentives and markets for rare earths are done. The scientific and technological challengers are discussed and some suggestions to lead a superconductivity national program are proposed. (M.C.K.) [pt

Superconducting magnets for model ship propulsion and for material tests of a nuclear fusion reactor

International Nuclear Information System (INIS)

Horiuchi, T.; Matsumoto, K.; Monju, Y.; Tatara, I.; Hamada, M.

1982-01-01

Nuclear fusion reactors, magnetically levitated trains, and MHD generators, etc., all need a very high magnetic field; which in order to be attained a means the application of superconductors is inevitable. This paper describes the development of ''CRYOZITT'', a superconductor featuring high current density and high mechanical strength. CRYOZITT has already been used in the manufacture of two race-track shaped superconducting magnets, and delivered to highly satisfied customers. (author)

Plasma oxidation of the high T/sub c/ superconducting perovskites

International Nuclear Information System (INIS)

Bagley, B.G.; Greene, L.H.; Tarascon, J.; Hull, G.W.

1987-01-01

A near room-temperature plasma oxidation process is shown to restore superconductivity and metalliclike behavior in oxygen deficient La/sub 2-//sub x/ Sr/sub x/ CuO/sub 4-//sub y/ and YBa 2 Cu 3 O/sub 7-//sub x/ compounds. In the YBa 2 Cu 3 O/sub 7-//sub x/ compound the conversion from an oxygen deficient n-type tetragonal to the p-type orthorhombic phase with a concomitant factor of 5 x 10 5 increase in room-temperature conductivity is also accomplished. This process is of technological importance because oxygen can be restored in these materials at temperatures compatible with device processing. Of scientific interest, the process allows us to carefully control the oxidation state and thereby systematically study the 90 and 55 K superconducting transitions in YBa 2 Cu 3 O/sub 7-//sub x/

Superconductivity

International Nuclear Information System (INIS)

Langone, J.

1989-01-01

This book explains the theoretical background of superconductivity. Includes discussion of electricity, material fabrication, maglev trains, the superconducting supercollider, and Japanese-US competition. The authors reports the latest discoveries

ac superconducting articles

International Nuclear Information System (INIS)

Meyerhoff, R.W.

1977-01-01

A noval ac superconducting cable is described. It consists of a composite structure having a superconducting surface along with a high thermally conductive material wherein the superconducting surface has the desired physical properties, geometrical shape and surface finish produced by the steps of depositing a superconducting layer upon a substrate having a predetermined surface finish and shape which conforms to that of the desired superconducting article, depositing a supporting layer of material on the superconducting layer and removing the substrate, the surface of the superconductor being a replica of the substrate surface

Superconducting TlCa2Ba2Cu3O9 thick films

International Nuclear Information System (INIS)

1994-01-01

GE Corporate Research and Development's (GE-CRD) program to develop the two-zone silver addition (TZSA) process for fabricating superconducting films of TlCa 2 Ba 2 Cu 3 O 9 has activities in the areas of (1) precursor preparation, (2) the thallium oxide vapor process, (3) the effects of post-synthesis annealing ambient and temperature on superconducting properties, (4) the influence of film stoichiometry and composition on superconducting properties, (5) microstructure and film growth mechanism, (6) the preparation of thicker films, (7) the fabrication of films on flexible substrates, and (8) process scale-up. As part of its effort under the ANL Pilot Center Agreement, GE-CRD has supplied to ANL a complete two-zone furnace, has provided consultation on its use and on the planning of experiments, has processed ANL samples in GE's furnaces to help define optimum process conditions, and has provided precursor and finished films as requested. These contributions are described more fully in the descriptions of the work performed at ANL presented elsewhere in this report. Under the Pilot Center Agreement work at GE-CRD has been directed toward the optimization of the TZSA process with emphasis on (A) process improvement, (B) effects of silver content on film properties, (C) the relationship between microstructure and J c , and (D) toward the assessment of the compatibility of silver substrates with the process chemistry

Superconductivity and fast proton transport in nanoconfined water

Science.gov (United States)

Johnson, K. H.

2018-04-01

A real-space molecular-orbital density-wave description of Cooper pairing in conjunction with the dynamic Jahn-Teller mechanism for high-Tc superconductivity predicts that electron-doped water confined to the nanoscale environment of a carbon nanotube or biological macromolecule should superconduct below and exhibit fast proton transport above the transition temperature, Tc ≅ 230 K (-43 °C).

High-temperature superconductivity

International Nuclear Information System (INIS)

Ginzburg, V.L.

1987-07-01

After a short account of the history of experimental studies on superconductivity, the microscopic theory of superconductivity, the calculation of the control temperature and its possible maximum value are presented. An explanation of the mechanism of superconductivity in recently discovered superconducting metal oxide ceramics and the perspectives for the realization of new high-temperature superconducting materials are discussed. 56 refs, 2 figs, 3 tabs

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

Quasiparticles in the superconducting state of high-Tc metals

International Nuclear Information System (INIS)

Amusia, M.Ya.; Shaginyan, V.R.

2003-01-01

The behavior of quasiparticles in the superconducting state of high-T c metals within the framework of the theory of superconducting state based on the fermion condensation quantum phase transition is considered. It is shown that the behavior coincides with the behavior of Bogoliubov quasiparticles, whereas the maximum value of the superconducting gap and other exotic properties are determined by the presence of the fermion condensate. If at low temperatures the normal state is recovered by the application of a magnetic field suppressing the superconductivity, the induced state can be viewed as Landau-Fermi liquid. These observations are in good agreement with recent experimental facts [ru

Magnetic shield effect simulation of superconducting film shield covering directly coupled HTS dc-SQUID magnetometer

International Nuclear Information System (INIS)

Terauchi, N.; Noguchi, S.; Igarashi, H.

2011-01-01

A superconducting film shield over a SQUID ring improves the robustness of the SQUID with respect to magnetic noise. Supercurrent in the SQUID magnetometer and the superconducting film shield were simulated. The superconducting film shield reduces the influence of the external magnetic field on the SQUID ring. An HTS SQUID is a high sensitive magnetic sensor. In recent years, the HTS SQUID is widely used in various applications. In some applications, high robustness with respect to magnetic noise is required to realize stable operation at outside of a magnetic shielding room. The target of this paper is a directly coupled HTS dc-SQUID magnetometer. To enhance the robustness of the SQUID magnetometer, use of a superconducting thin film shield has been proposed. The magnetic field directly penetrating the SQUID ring causes the change of the critical current of Josephson junction, and then the SQUID magnetometer transitions into inoperative state. In order to confirm the magnetic shield effect of the superconducting film shield, electromagnetic field simulation with 3D edge finite element method was performed. To simulate the high temperature superconductor, E-J characteristics and c-axis anisotropy are considered. To evaluate the effect of the superconducting film shield, an external magnetic field which is supposed to be a magnetic noise is applied. From the simulation results, the time transition of the magnetic flux penetrating the SQUID ring is investigated and the effect of the superconducting film shield is confirmed. The amplitude of the magnetic flux penetrating the SQUID ring can be reduced to about one-sixth since the superconducting film shield prevents the magnetic noise from directly penetrating the SQUID ring.

Ultrahigh pressure superconductivity in molybdenum disulfide

Energy Technology Data Exchange (ETDEWEB)

Chi, Zhenhua [Chinese Academy of Sciences (CAS), Hefei (China); Yen, Feihsiang [Chinese Academy of Sciences (CAS), Hefei (China); Peng, Feng [Luoyang Normal Univ., Luoyang (China); Zhu, Jinlong [Univ. of Nevada, Las Vegas, NV (United States); Zhang, Yijin [Univ. of Tokyo, Tokyo (Japan); Chen, Xuliang [Chinese Academy of Sciences (CAS), Hefei (China); Yang, Zhaorong [Chinese Academy of Sciences (CAS), Hefei (China); Nanjing Univ., Nanjing (China); Liu, Xiaodi [Chinese Academy of Sciences (CAS), Hefei (China); Ma, Yaming [Jilin Univ., Changchun (China); Zhao, Yusheng [Univ. of Nevada, Las Vegas, NV (United States); Kagayama, Tomoko [Osaka Univ., Osaka (Japan); Iwasa, Yoshihiro [Univ. of Tokyo, Tokyo (Japan); RIKEN Center for Emergent Matter Science (CEMS), Wako (Japan)

2015-03-18

Superconductivity commonly appears under pressure in charge densit wave (CDW)-bearing transition metal dichalcogenides (TMDs)^1,2, but ha emerged so far only via either intercalation with electron donors³ or electrostati doping⁴ in CDW-free TMDs. Theoretical calculations have predicted that th latter should be metallized through bandgap closure under pressure^5,6, bu superconductivity remained elusive in pristine 2H-MoS₂ upon substantia compression, where a pressure of up to 60 GPa only evidenced the metalli state^7,8. Here we report the emergence of superconductivity in pristine 2H-MoS at 90 GPa. The maximum onset transition temperature T_c^(onset) of 11.5 K, th highest value among TMDs and nearly constant from 120 up to 200 GPa, is wel above that obtained by chemical doping3 but comparable to that obtained b electrostatic doping4. T_c^(onset) is more than an order of magnitude larger tha present theoretical expectations, raising questions on either the curren calculation methodologies or the mechanism of the pressure-induced pairin state. Lastly, our findings strongly suggest further experimental and theoretical effort directed toward the study of the pressure-induced superconductivity in all CDWfre TMDs.

Superconducting fluctuation effect in CaFe0.88Co0.12AsF

Science.gov (United States)

Xiao, H.; Gao, B.; Ma, Y. H.; Li, X. J.; Mu, G.; Hu, T.

2016-11-01

Out-of-plane angular dependent torque measurements were performed on CaFe0.88Co0.12AsF single crystals. Superconducting fluctuations, featured by magnetic field enhanced and exponential temperature dependent diamagnetism, are observed above the superconducting transition temperature T c, which is similar to that of cuprate superconductors, but less pronounced. In addition, the ratio of T c versus superfluid density follows well the Uemura line of high-T c cuprates, which suggests the exotic nature of the superconductivity in CaFe0.88Co0.12AsF.

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.

Superconducting muon channel at J-PARC

International Nuclear Information System (INIS)

Shimomura, K.; Koda, A.; Strasser, P.; Kawamura, N.; Fujimori, H.; Makimura, S.; Higemoto, W.; Nakahara, K.; Ishida, K.; Nishiyama, K.; Nagamine, K.; Miyake, Y.

2009-01-01

The Muon Science Laboratory at the Materials and Life Science Facility is now under construction in Japan Proton Accelerator Research Complex (J-PARC), where four types of muon channels are planned to be installed. A conventional superconducting muon channel will be installed at the first stage, which can extract surface (positive) muons and decay positive/negative muons up to 120 MeV/c, and the expected muon yield is a few 10 6 /s at 60 MeV/c (for both positive and negative). This channel will be used for various kinds of experiments like muon catalyzed fusion, μSR and nondestructive elements analysis. The present status of the superconducting muon channel is briefly reported.

Development of a superconducting rotating-gantry for heavy-ion therapy

International Nuclear Information System (INIS)

Iwata, Y.; Noda, K.; Murakami, T.; Shirai, T.; Furukawa, T.; Fujita, T.; Mori, S.; Mizushima, K.; Shouda, K.; Fujimoto, T.; Ogitsu, T.; Obana, T.; Amemiya, N.; Orikasa, T.; Takami, S.; Takayama, S.

2013-01-01

An isocentric superconducting rotating-gantry for heavy-ion therapy is being developed. This rotating gantry can transport heavy ions having 430 MeV/u to an isocenter with irradiation angles of over ±180°, and is further capable of performing fast raster-scanning irradiation. For the magnets, combined-function superconducting-magnets are to be employed. All of the superconducting magnets have been designed, and their magnetic-field distributions were calculated by using a 3D electromagnetic-field solver. With the calculated magnetic-fields, beam-tracking simulations were performed to evaluate the field quality of the superconducting magnets. Beam profiles as well as phase-space distributions at the isocenter, as calculated by simulations, agreed well with those of linear beam-optics calculations, proving validity of the final design for the magnets. Three superconducting magnets were manufactured, and are being tested. In this paper, results of tracking simulations as well as test results for the superconducting magnets are presented

Superconducting Cable Development for Future High Energy Physics Detector Magnets

Science.gov (United States)

Horvath, I. L.

1995-11-01

Under the leadership of the Swiss Federal Institute of Technology (ETHZ) an international ad hoc collaboration for superconducting cables developed an aluminium stabilised superconducting cable for future detector magnets. With the financial support of the Swiss government, this R&D work was carried out for the European Organisation for Nuclear Research (CERN). In this report the manufacturing process is described and results of the quality control measurements are summarised. These tests showed that the industrial manufacturing of an aluminium stabilised superconducting cable is feasible.

The world's first supply ship powered by natural gas

International Nuclear Information System (INIS)

2003-01-01

The article describes the newly developed natural gas powered supply ship ''Viking Energy'', which reduces the emission of NOx by 200 tonnes per year. The shipping company has for many years been working on the developing of environmentally friendly ships with less fuel consumption. The gas is stored in liquid form at a temperature of 160 o C. The engines can run on gas or diesel as needed. These dual-fuel engines offers great flexibility, which is very desirable since liquid natural gas is not widely available along the coast. This type of engine has been used in power stations and on offshore platforms, but not in ships. The operating conditions are quite different for ships than for power stations. So far, both investment and operating costs are higher than for conventional ships

Superconductivity. Quasiparticle mass enhancement approaching optimal doping in a high-T(c) superconductor.

Science.gov (United States)

Ramshaw, B J; Sebastian, S E; McDonald, R D; Day, James; Tan, B S; Zhu, Z; Betts, J B; Liang, Ruixing; Bonn, D A; Hardy, W N; Harrison, N

2015-04-17

In the quest for superconductors with higher transition temperatures (T(c)), one emerging motif is that electronic interactions favorable for superconductivity can be enhanced by fluctuations of a broken-symmetry phase. Recent experiments have suggested the existence of the requisite broken-symmetry phase in the high-T(c) cuprates, but the impact of such a phase on the ground-state electronic interactions has remained unclear. We used magnetic fields exceeding 90 tesla to access the underlying metallic state of the cuprate YBa2Cu3O(6+δ) over a wide range of doping, and observed magnetic quantum oscillations that reveal a strong enhancement of the quasiparticle effective mass toward optimal doping. This mass enhancement results from increasing electronic interactions approaching optimal doping, and suggests a quantum critical point at a hole doping of p(crit) ≈ 0.18. Copyright © 2015, American Association for the Advancement of Science.

Magnetic levitation force between a superconducting bulk magnet and a permanent magnet

International Nuclear Information System (INIS)

Wang, J J; He, C Y; Meng, L F; Li, C; Han, R S; Gao, Z X

2003-01-01

The current density J(ρ, z) in a disc-shaped superconducting bulk magnet and the magnetic levitation force F SBM z exerted on the superconducting bulk magnet by a cylindrical permanent magnet are calculated from first principles. The effect of the superconducting parameters of the superconducting bulk is taken into account by assuming the voltage-current law E = E c (J/J c ) n and the material law B = μ 0 H. The magnetic levitation force F SBM z is dominated by the remnant current density J' 2 (ρ, z), which is induced by switching off the applied magnetizing field. High critical current density and flux creep exponent may increase the magnetic levitation force F SBM z . Large volume and high aspect ratio of the superconducting bulk can further enhance the magnetic levitation force F SBM z

Liner Shipping Fleet Deployment with Sustainable Collaborative Transportation

Directory of Open Access Journals (Sweden)

Gang Du

2016-02-01

Full Text Available Facing sharp competition in the market for shipping companies, it is necessary to make reasonable and efficient decisions to optimize the container shipping line network so as to improve the shipping efficiency and reduce the transportation cost, as well as to realize the transportation sustainability. Therefore, the liner ship fleet deployment problem with collaborative transportation is proposed in this paper. This problem is formulated as a mixed-integer linear programming model that takes collaborative transportation into consideration. The model includes fixed cost, variable cost, berth cost, transport cost, penalty, compensation cost, and so on. To achieve the sustainable development of collaborative transportation, the shipping companies could make a selection between the internal routes and the external routes to serve each task by comparing the distance between the above routes. A real Asia-Europe-Oceania numerical experiment shows that the proposed sustainable collaborative transportation model can be efficiently solved by C++ calling ILOG CPLEX. Results demonstrate that the optimized shipping line network with sustainable collaborative transportation can improve the service efficiency, as well as the service level of shipping companies.

Negative effects of crystalline-SiC doping on the critical current density in Ti-sheathed MgB2(SiC)y superconducting wires