Showing papers on "High-temperature superconductivity published in 1994"
Book•
30 Sep 1994
TL;DR: Superconductivity: Introduction and Overview as mentioned in this paper The theory of high temperature superconductivity (HTSC) has been studied extensively in the literature and applied in many industrial applications.
Abstract: Superconductivity: Introduction and Overview. Magnetism and Currents in Superconductors. Refrigeration. Industrial Applications. Sensitive Applications. Basic Concepts of Theory of Superconductivity. The New Superconductors. High Temperature Superconductivity (HTSC) Basic Principles: Structure. Phase Diagrams and Equilibrium. Effects of Doping. Mechanical Properties. HTSC Theory. Weak Links. Carrying Electricity: Flux Line Motion and Flux Pinning. Processing Methods. HTSC Wire. Protecting against Damage. AC Losses. Electric Power Applications of HTSC: Transmission Lines. Levitation. Superconducting Magnetic Energy Storage. Electric Machinery. Fault Current Limiters. Future Possibilities: New Refrigerators. Applications to Measurement and Process Control. High Magnetic Fields. Organic Superconductors. Aerospace Applications. Appendixes. Index.
156 citations
TL;DR: In this paper, a vector network analyzer is used to measure the complex surface impedance of the mixed state of superconducting thin films over the broad frequency range 45 MHz-20 GHz.
Abstract: We present a new technique to measure the complex surface impedance of the mixed state of superconducting thin films over the broad frequency range 45 MHz–20 GHz. The surface impedance is extracted from measurements of the complex reflection coefficient made on the film using a vector network analyzer. The technique takes advantage of a special geometry in which the self‐fields from currents flowing in the film are everywhere parallel to the film surface, making it an ideal configuration in which to study vortex dynamics in superconductors. The broadband nature of the measurement system allows us to explore a region of magnetic field–temperature–frequency parameter space of superconductors previously inaccessible with other measurement techniques. The power of the technique is illustrated by measurements on thin films of the high temperature superconductor YBa2Cu3O7−δ.
123 citations
IBM1
TL;DR: By considering transport in the neighborhood of a SP that the VHS does provide the sharp feature needed to explain the temperature-independent thermopower, even though the overall bandwidth is of order 1 eV, the universal relationship between the thermopOWER and transition temperature now receives a natural explanation.
Abstract: The thermopower in cuprate superconductors shows a quasiclassical temperature independence rather than the $T$-linear behavior of a Fermi liquid, and scales in an approximately universal manner with doping. It is shown that standard transport theory at a van Hove singularity in the band structure can explain both the linear resistivity and these remarkable features of the thermopower in cuprates.
87 citations
79 citations
79 citations
TL;DR: In this paper, the authors presented models and calculated results for the fluxpinning-induced magnetostriction in type-II superconductors, and the results were used for computer simulations and the hysteresis loops were calculated over a wide range of the relevant parameters.
Abstract: Models and calculated results are presented for the flux‐pinning‐induced magnetostriction in type‐II superconductors. Three models are considered for the critical state; the original Bean model, the Kim model, and the exponential model in which the critical current density is assumed to depend exponentially on the flux density. The analytic expressions of the length change under the magnetic field are derived for specimens having infinite slab geometry and under the assumption that the reversible part of the total magnetization is negligibly small. The results are used for computer simulations and the hysteresis loops are calculated over a wide range of the relevant parameters. Since the pinning‐induced magnetostriction reveals the pinning force directly, the hysteresis loops for each model have different features which are discussed in detail. It is also shown that the pinning force of the sample can be directly inferred from the width of the magnetostriction hysteresis loop. Finally, the experimental results on high‐temperature superconductors are discussed in comparison with the calculated results.
76 citations
01 Jan 1994
76 citations
71 citations
Book•
01 Jan 1994
TL;DR: In this article, heavy-fermion magnetism and superconductivity of high-temperature superconductors are discussed. And the normal state of the High Temperature Superconductors is discussed.
Abstract: Heavy Fermion Insulators (J. Robert Schrieffer) Heavy Fermion Magnetism and Superconductivity (E. Abrahams) The Metal-Insulator Transition (S. Trugman) The Superconductor-Insulator Transitions (K. Bedell) Lattice Effects in High-Temperature Superconductors (D. Pines) Spin Fluctations and High-Temperature Superconductors (J. Wilkins) The Normal State of the High Temperature Superconductors.
68 citations
01 Jan 1994
TL;DR: Paranthaman et al. as mentioned in this paper reviewed the history of the discovery of Tl-based HTSC Oxides and the development of Thallium Cuprate Superconductors.
Abstract: "Historical Perspective on the Discovery of Tl-Based HTSC Oxides, Allen M. Hermann Solid-State Chemistry of Thallium Oxides, J. Gopalakrishnan Crystallographic Aspects, Yuichi Shimakawa Extended Defects and Redox Mechanisms in Thallium Cuprates, Bernard Raveau, Maryvonne Hervieu, and Claude Michel Structures and Superstructures of Tl-Ba-Ca-Cu-O Superconductors, A. W. Hewat and E. A. Hewat Synthesis of Tl-Based High-Tc Superconductive Oxides, Eli Ruckenstein and Nae-Lih Wu Chemical Characterization of Thallium Cuprate Superconductors, Mariappan Paranthaman, Arumugam Manthiram, and John B. Goodenough Single-Crystal Growth and Characterization of Thallium Cuprate Superconductors: A Review, Mariappan Paranthaman, H. M. Duan, and Allen M. Hermann Tl-Based HTSC Films for Microelectronics Applications, David S. Ginley Spray Pyrolysis, L. Pierre de Rochemont and Michael R. Squillante Liquid-Gas Solidification Method for Synthesis of Tl-Based HTSC Oxides, Ho Sou Chen Electrodeposited Tl-Ba-Ca-Cu-O Superconductors, R. N. Bhattacharya and R. D. Blaugher Tl-Ca-Ba-Cu-O Electronics, J. S. Martens TBCCO Ag-Sheathed Tapes, Koji Tada, Hiromi Takei, and Yasuko Torii Effects of Inherent (Auto) Doping and Oxygen Nonstoichiometry and Their Relationship to the Band Structure of Tl-Based Superconductors, R. S. Liu and Peter P. Edwards Structureal Origin of Holes in Thallium Cuprate-Based High-Tc Superconductors, M. A. Subramanian and Ashok K. Gangull Dependence of Tc on the Hole Concentration in Superconducting Thallium Cuprates with Single Tl-O Layers, C. N. R. Rao Site-Selective Substitution in Tl Cuprates, R. M. Iyer and G. M. Phatak Thermal Stability of Tl-Ba-Ca-Cu-O High-Tc Superconductors, Ken H. Sandhage and Patrick K. Gallagher Magnetic Properties of Thallium-Based Superconductors, Timir Datta Effects of Pressure on Thallium-Based Superconductors, Norman E. Moulton and Earl F. Skelton Specific Heat of Thallium Oxide Superconductors, Robert A. Fisher, Norman E. Phillips, and Joel E. Gordon Infrared Studies of Thallium Cuprate Superconductors, Karl F. Renk X-Ray Photoemission of Tl-Based Cuprate Superconductors, Yasuo Fukuda, Teruo Suzuki, and Masayasu Nagoshi Nuclear Resonance Studies of Tl-Based High-Tc Superconductors, Hans B. Brom Normal-State Transport Properties of TBCCO, D. G. Naugle and A. B. Kaiser Tunneling Spectroscopy of Thallium-Based High-Temperature Superconductors, John Moreland Band Structures of Tl-Ba-Ca-Cu-O Materials, Roland E. Allen and Brent A. Richert Thallium Cuprate Research by the U. S. Government, M. S. Davis and S. A. Wolf Thallium Safety, Gary E. Myers Prospects and Potential for Thallium Cuprate Superconductors, J. V. Yakhmi and Allen M. Hermann "
67 citations
Patent•
28 Nov 1994
TL;DR: In this article, a conductor suitable for use in oxide-based electronic devices and circuits is disclosed, where the conducting oxide CaRuO3 is used as the normal material in an SNS junelion with YBa2 Cu3 O7-δ as superconductor.
Abstract: A conductor suitable for use in oxide-based electronic devices and circuits is disclosed. Metallic oxides having the general composition AMO3, where A is a rare or alkaline earth or an alloy of rare or alkaline earth elements, and M is a transition metal, exhibit metallic behavior and are compatible with high temperature ceramic processing. Other useful metallic oxides have compositions (A1-x A'x)A"2 (M1-y M'y)3 O7-δ or (A1-x A'x)m (M1-y M'y)n O2m+n, where 0≦x, y≦1 and 0.5≦m, n≦3, A and A' are rare or alkaline earths, or alloys of rare or alkaline earths, A' and A" are alkaline earth elements, alloys of alkaline earth elements, rare earth elements, alloys of rare earth elements, or alloys of alkaline earth and rare earth elements, and M and M' are transition metal elements or alloys of transition metal elements. The metallic oxides grow epitaxially on oxide superconductors as well as on substrates and buffer layers commonly used for growth of oxide superconductors. The oxide superconductors can also be grown epitaxially on these metallic oxides. Vastly improved performance of superconductor-normal-superconductor (SNS) junctions in high temperature superconductor materials are obtained when the normal material is a metallic oxide of the type disclosed. In the preferred embodiment, the conducting oxide CaRuO3 is used as the normal material in an SNS junelion with YBa2 Cu3 O7-δ as superconductor. A dc superconducting quantum interference device (SQUID) functioning at 77K fabricated with this type of junction exhibits large modulation and low noise.
01 Jan 1994
TL;DR: In this paper, it is shown that point defects can be effective pinning centers for magnetic flux lines increasing the transport critical current density in single crystalline materials, while extended defects in the cuprate superconductors in most cases form weak links reducing the transportcritical current density.
Abstract: Defects can determine the electrical transport properties of solids. This statement also holds true for the high-temperature superconductors. In these materials defects play an important role concerning two aspects. On the one hand, high transport critical current densities in these materials can only be achieved by the presence of a high density of defects providing pinning centers for the magnetic flux lines. It is well-known that ideal defects for flux pinning should have a diameter equal to about the coherence length. Furthermore, their density should be high enough to provide sufficient flux pinning at high magnetic fields. Due to the short coherence length of the cuprate superconductors their order parameter is depressed considerably by local defects. In this way point defects can be effective pinning cites for magnetic flux lines increasing the transport critical current density in single crystalline materials. On the other hand, extended defects in the cuprate superconductors in most cases form weak links reducing the transport critical current density. Extended defects in these materials seem to be organized in planes as, for example, stacking faults or small and large-angle grain boundaries. This shows that defects can both increase and decrease the transport critical current density depending on their detailed nature. Grain boundaries are probably the most important defects in the cuprate superconductors. On the one hand, they are known to cause disappointingly low transport critical current density in polycrystalline materials thereby limiting high current density applications.
TL;DR: In this paper, the superconducting pairing state is shown to be dx2-y2, and it is the coupling of planar quasiparticles to the experimentally measured planar electronic spin fluctuation excitations which determines the normal state properties, and makes possible high temperature superconductivity.
Abstract: I review theoretical calculations and experimental measurements which demonstrate that the superconducting pairing state is dx2-y2, and that it is the coupling of planar quasiparticles to the experimentally measured planar electronic spin fluctuation excitations which determines the normal state properties, and makes possible high temperature superconductivity.
TL;DR: In this paper, a model for the high temperature part of the conductor-superconductor transition region of high T/sub c/superconductors is presented, where the model incorporates number and mobility noises of charge carriers.
Abstract: Very recently, significant progress has been achieved in the understanding of the excessive strength and behavior of the conductance noise in the conductor-superconductor transition region of high T/sub c/ superconductors. For the high temperature part of the conductor-superconductor transition region, the model incorporates number and mobility noises of charge carriers: while in the low temperature part of the transition, classical and novel percolation noise effects (including possible effects due to flux motion) determine the behavior of the measured noise. In present high-quality (in situ annealed) films, the novel percolation noise effect ("p-noise," Phys. Rev. Lett., vol. 71, p. 2817, 1993) seems to be the most important. Some other important topics will also be briefly examined in this review: magnetic noise, noise in devices, and practical problems of measurements (e.g., comparison of the noise of different materials, temperature fluctuations). >
TL;DR: In this paper, it was shown that the conventional flux-motion mechanism does not play a major role in dissipation in high-Tc superconductors, and instead, mechanisms that take into account the superconducting fluctuation effect in the super-conducting order parameter have been proposed and have successfully been applied to analyse experimental results.
Abstract: The evolution of resistivity in the mixed state of high-Tc superconductors has been a source of debate in the fundamental problem of whether or not energy dissipation originates from the Lorentz-force-driven flux motion. The conventional flux-creep and flux-flow models are essentially based on this mechanism and have frequently been used to explain the broad resistive transition in magnetic fields in high-Tc superconductors. However, recent intensive experimental studies of high-quality single crystals, such as (La1-xSrx)2CuO4, YBa2Cu3O4, Bi2Sr2CaCu2O8+ delta , etc, have revealed clear evidence that excludes the contribution of the effect of flux motion to the resistivity broadening, indicating that the conventional flux-motion mechanism does not play a major role in dissipation in high-Tc superconductors. Instead, mechanisms that take into account the superconducting fluctuation effect in the superconducting order parameter have recently been proposed and have successfully been applied to analyse experimental results. Possible similarities between the fundamental concepts of superconducting fluctuation models and the Kosterlitz-Thouless transition have also been discussed.
TL;DR: In this article, it is argued that the low energy physics of high temperature superconductors is governed by the scattering of mobile holes from local collective modes consisting of charge stripes and antiphase spin domains, as suggested by the competition between phase separation and the long range Coulomb force.
Abstract: It is argued that the low energy physics of high temperature superconductors is governed by the scattering of mobile holes from local collective modes consisting of charge stripes and antiphase spin domains, as suggested by the competition between phase separation and the long range Coulomb force. Normal state charge transport is given by a paraconductivity associated with a non standard composite Frohlich-BCS pairing. In the ordered state, the order parameter is s -wave for tetragonal materials but, in other materials, there is a substantial mixing of d -wave via an unusual amplification of local or global asymmetry.
Book•
27 Dec 1994
TL;DR: In this paper, the discovery of high-temperature superconductivity was discussed and a new class of Oxide superconductors were introduced, and the properties of these properties were analyzed.
Abstract: 1. Introduction.- 1.1 The Discovery of High-Temperature Superconductivity.- 1.2 A New Class of Oxide Superconductors.- 1.3 General Properties of Oxide Superconductors.- 2. Crystal Structure.- 2.1 The Structure of Ba1-xKxBiO3.- 2.2 Lai1-xMxCuO4 Compounds.- 2.2.1 The Structure of La2-xMxCuO4-y.- 2.2.2 A Phenomenological Theory of Structural Phase Transitions in La2CuO4- Based Compounds.- 2.3 Nd2-xCexCuO4 Compounds.- 2.4 Y-Ba-Cu-O-Based Compounds.- 2.4.1 The Structure of YBa2Cu3O7-y.- 2.4.2 Modifications of the YBCO Structure.- 2.5 Bi-Ca-Sr-Cu-O and Tl-Ca-Ba-Cu-O Compounds.- 3. Antiferromagnetism in High-Temperature Superconductors.- 3.1 Antiferromagnetism in La2CuO4 Compounds.- 3.1.1 Magnetic Structure.- 3.1.2 A Phenomenological Theory of Magnetic Phase Transitions in La2CuO4.- 3.1.3 Spin Dynamics in La2?xMxCuO4.- 3.2 Antiferromagnetism in YBa2Cu3O6+x Compounds.- 3.2.1 The Magnetic Phase Diagram.- 3.2.2 Spin Dynamics in YBa2Cu3O6+x.- 3.2.3 Antiferromagnetism of Rare-Earth Ions in REBa2Cu3O6+x.- 3.3 Spin Dynamics Studied by the NMR Method.- 3.3.1 The Knight Shift.- 3.3.2 Spin-Lattice Relaxation.- 4. Thermodynamic Properties of High-Temperature Superconductors.- 4.1 The Anisotropic Ginsburg-Landau Model.- 4.2 Specific Heat.- 4.3 Magnetic Properties.- 5. Electronic Properties of High-Tc Superconductors.- 5.1 Crystal Chemistry of Oxide Superconductors.- 5.2 The Effect of Impurity Substitution.- 5.3 Theoretical Electronic Band-Structure Studies.- 5.3.1 Electronic Band-Structure Calculations.- 5.3.2 Effective Hamiltonians in Models of La2CuO4.- 5.4 Experimental Studies of the Electronic Structure.- 5.4.1 High-Energy Scale Spectroscopy.- 5.4.2 Studies of the Fermi Surface.- 5.4.3 Optical Electron Spectroscopy.- 5.5 Transport Properties.- 5.5.1 Resistivity.- 5.5.2 Hall Effect.- 5.5.3 Thermopower and Heat Conductivity.- 5.6 Superconducting Gap.- 5.6.1 Tunneling Experiments.- 5.6.2 Other Experiments.- 6. Lattice Dynamics and Electron-Phonon Interaction.- 6.1 Phonon Spectra - Neutron Scattering.- 6.2 Optical Investigations.- 6.3 Theoretical Models.- 7. Theoretical Models of High-Temperature Superconductivity.- 7.1 Quasi-Particles in Models with Strong Correlation.- 7.1.1 Model Hamiltonians.- 7.1.2 The One-Hole Quasi-Particle Spectrum.- 7.1.3 Spin Fluctuation Spectrum.- 7.2 Superconductivity in Systems with Strong Correlations.- 7.2.1 Unconventional Ground States.- 7.2.2 Superconductivity in the t-J Model.- 7.2.3 Superconductivity in the p-d Model.- 7.3 Antiferromagnetism and Superconductivity.- 7.4 Electron-Phonon Mechanism.- 7.4.1 Isotope Effect.- 7.4.2 Strong Electron-Phonon Coupling.- 7.4.3 Anharmonic Model of a Superconductor.- 7.4.4 Polarons and Bipolaron Superconductivity.- 7.4.5 Weak Coupling in the Quasi-Two-Dimensional Lattice.- 7.4.6 Spin-Fluctuation and Electron-Phonon Interactions.- 7.5 Exciton Models.- 7.5.1 Plasmon Model.- 7.5.2 Jahn-Teller Excitations and the d-d Model.- 7.5.3 Coulomb Interaction in the Multiband Models.- 8. Conclusion.- References.
IBM1
TL;DR: The superconducting transport characteristics of HgBa2 CaCu2O6+δ (Hg-1212) films and grain-boundary junctions grown on (100)-oriented SrTiO3 bicrystal substrates have been investigated and show weak-link behavior qualitatively resembling that of a resistively shunted junction.
Abstract: The superconducting transport characteristics of HgBa2 CaCu2O6+δ (Hg-1212) films and grain-boundary junctions grown on (100)-oriented SrTiO3 bicrystal substrates have been investigated. The films exhibit a zero-resistance temperature of ∼120 kelvin and sustain large critical current densities, with values as high as 106 amperes per square centimeter at around 100 kelvin. On the other hand, the grain boundaries behave as weak links, with substantially lower critical currents, as is observed for other cuprate superconductors. A reduction of three orders of magnitude in critical current was observed for transport across a 36.8° grain boundary. The current-voltage characteristics of bridges across such a grain boundary show weak-link behavior qualitatively resembling that of a resistively shunted junction. Single-level direct-current superconducting quantum interference devices (SQUIDs) have been fabricated with such bicrystal junctions. These SQUIDs show clear periodic voltage modulations when subjected to applied magnetic fields. The SQUIDs operate at temperatures as high as 111.8 kelvin, which makes them attractive for operation in portable sensors and devices that utilize nonconventional cooling methods.
TL;DR: The Wohlleben effect was first observed in the field-cooled regime of high-Tc superconductors as mentioned in this paper, where the magnetic response of some HTSC at very low fields (≲ 1Oe) becomes paramagnetic.
Abstract: Recently a quite unexpected phenomenon was observed during the study of the magnetic properties of High-Tc superconductors: In the field-cooled regime the magnetic response of some HTSC at very low fields (≲ 1Oe), instead of being diamagnetic, becomes paramagnetic. Such behavior is perfectly reproducible and stable. This effect is now called the Wohlleben Effect. The samples showing the Wohlleben effect also display anomalous behavior in some other properties (microwave absorption, second harmonic of magnetic susceptibility). In this paper a survey is given of the experimental studies of this and related phenomena, carried out in different laboratories. Corresponding theoretical models are also discussed. The effect is attributed to the formation of spontaneous currents (spontaneous orbital magnetic moments) in the ground state of the weak link network in case when Josephson coupling between certain grains is negative (π-contacts). Microscopic mechanisms of inverse Josephson coupling are discussed especially in connection with the possible unconventional pairing in HTSC.
TL;DR: In this article, a critical study of the work done up to now shows that the most important question arises from a correct interpretation of the correlation mechanisms that determine the components and the weights of the copper configurations d8, d9 and d10L in XPS spectra.
TL;DR: In this paper, the spectral properties of high-temperature superconductors are reviewed and a set of criteria for assessing surface quality are determined, and these criteria are then used to evaluate the various surface preparation procedures reported in the literature.
TL;DR: In this paper, the theory and experiments of vibrating high-temperature superconductors (period 1988-94) are reviewed, in particular results on the elastic coupling between the flux line lattice and pinning centres, magnetization measurements, flux diffusion, possible phase transitions and matching effects of the flux-line lattice.
Abstract: This work reviews the theory and experiments of vibrating high-temperature superconductors (period 1988-94). In particular we discuss results on the elastic coupling between the flux line lattice and pinning centres, magnetization measurements, flux diffusion, possible phase transitions and matching effects of the flux line lattice. Special emphasis has been devoted to the comparison of these results with results obtained by more conventional methods such as AC susceptibility, low-frequency torsional oscillators, I-V curves and surface impedance measurements.
Patent•
19 Dec 1994TL;DR: In this paper, a technique for evaluation of high-T c superconducting films and single crystals is based on measurement of temperature dependence of differential optical reflectivity of high T c materials.
Abstract: A technique for evaluation of high-T c superconducting films and single crystals is based on measurement of temperature dependence of differential optical reflectivity of high-T c materials. In the claimed method, specific parameters of the superconducting transition such as the critical temperature, anisotropy of the differential optical reflectivity response, and the part of the optical losses related to sample quality are measured. The apparatus for performing this technique includes pump and probe sources, cooling means for sweeping sample temperature across the critical temperature and polarization controller for controlling a state of polarization of a probe light beam.
TL;DR: In this article, the authors developed a set of strategies for searching for high temperature superconductors in highly correlated solids, with particular reference to the conducting polymers, by combining experimental information and some very general aspects of the current theory of highly correlated systems.
TL;DR: In this article, the onset temperature for magnetic irreversibility in high-temperature superconductors has been investigated as a function of frequency (0.2 Hz⩽f ⩽65 000 Hz) and DC magnetic field.
Abstract: The onset temperature, Tirr, for magnetic irreversibility in high-temperature superconductors has been investigated as a function of frequency (0.2 Hz⩽f⩽65 000 Hz) and DC magnetic field (0
TL;DR: In this paper, the anyon approach to the t-J model is shown to predict a conventional BCS order parameter of d x 2 − y 2 + iϵd xy symmetry, with ϵ roughly 3 times the doping fraction, which is consistent with these experiments but not demonstrated by them.
Abstract: It is argued that recent Josephson junction and point-contact tunneling experiments, interpreted as intended by their authors, indicate that time0reversal symmetry breaking occurs at surfaces of cuprate superconductors. The variation among experiments and the failure of previous searches to find T violation are ascribed to disorder and effects of three-dimensionality. The anyon approach to the t-J model is shown to predict a conventional BCS order parameter of d x 2 − y 2 + iϵd xy symmetry, with ϵ roughly 3 times the doping fraction δ, which is consistent with these experiments but not demonstrated by them.
TL;DR: In this paper, the authors discuss the influences of imperfections on both T c and the low-temperature properties of cuprate superconductors, and suggest a possible hierarchy of superconducting cuprates.
Abstract: I review recent theoretical calculations and experimental measurements which demonstrate that the planar excitations in the normal state of the superconducting cuprates are best described as a nearly antiferromagnetic Fermi liquid. Its anomalous transport, optical and quasiparticle properties arise from the magnetic interaction between the quasiparticles which gives rise to a high T c transition to a superconducting state with d x 2 − y 2 symmetry now observed in nuclear magnetic resonance, penetration depth, SQUID and other tunneling experiments, Raman and neutron scattering, photoemission, and numerous other experiments. I discuss the influences of imperfections on both T c and the low-temperature properties, review experiments on dirty d-wave superconductors, and suggest a possible “intrinsic imperfection” hierarchy of cuprate superconductors.