Published for the Division of Materials Sciences, Office of Basic Energy Sciences, USDOE, under Contract W-7405-eng-82 with the Ames Laboratory, Iowa State University. Funded by DMS/BES/USDOE, ARPA, ONR, NSF, EPRI, and other agencies, organizations, and individuals.
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YBa2Cu3O7-d
Polarized and unpolarized triple-axis neutron measurements by P. Dai (Oak Ridge) et al. on an underdoped crystal of YBa2Cu3O6.6 (Tc = 62.7 K) show that, contrary to earlier evidence, the spin excitations in the superconducting state are essentially the same as those in the fully doped material, except that the unusual 41 meV resonance is observed at 34.8 meV. The normal-state spin excitations are characterized by a weakly energy-dependent continuum whose temperature dependence shows the clear signature of a superconducting gap at Tc. The low-temperature gap is 28 meV, considerably larger than that predicted in the BCS weakcoupling limit. The observed behavior of the temperature-dependent shifts in spectral weight, however, may indicate the influence of superconductivity above Tc, since the same effects are not observed in highly doped materials. This behavior thus supports the idea of a pseudogap opening above Tc in underdoped cuprates.
The Tc suppression and residual resistivities rho_0 in Cu-sitesubstituted thin films of YBa2(Cu1-zMz)3O7-d (M = Zn, Ni) have been reinvestigated by T. Kluge et al. (Mainz). The authors found that for low concentrations (z <= 4%) the Zn and Ni atoms preferentially occupy the CuO2-plane Cu sites, whereas for higher concentrations the CuO-chain Cu sites are also occupied. Although the residual resistivities of Ni and Zn differ only slightly, the Tc suppression of Zn is 2.3 times that of Ni. To reconcile the measured resistivities with predictions of a two-dimensional scattering model, it is necessary to assume a scattering potential of finite range and to take scattering phase shifts d_l of higher angular momentum (l > 0) into account. The authors also discuss the different Tc suppression rates for Zn and Ni within this picture.
The chemical diffusion of oxygen in oxygen-deficient orthorhombic YBa2Cu3O6+x powder samples has been measured by K. Conder and Ch. Krueger (ETH Zurich). The authors used a moving-boundary model of oxidation to characterize the chemical diffusion of oxygen, and found the rate of boundary movement at constant oxidation temperature to be constant in time. The authors emphasize that the results of their work can be used to estimate the time necessary for oxidation at various temperatures and grain sizes.
Microstructural changes of a melt-processed YBa2Cu3O7-d specimen during oxygen annealing have been studied by H.-G. Lee et al. (SRL-KAERI) who directly observed a polished surface. A nonuniform orthorhombic to tetragonal phase transition, induced by nonuniform oxygen diffusion, occurred in the polished surface, and microcracks were generated along the oxygen-rich plane. The authors conclude that the inhomogeneous oxygen diffusion can be explained by a stress effect and that the cracks did not act as a diffusion channel for oxygen atoms.
A preprint by S. Sathyamurthy et al. (TCSUH) reports that partial removal of liquid phase during melt texturing has demonstrated the potential to significantly enhance grain-boundary coupling and to improve the transport critical current of bulk polycrystalline YBCO superconductors. This paper describes how the processing conditions affect current-transport characteristics and the number of cracks at the grain boundary.
Numerical simulations of the melt growth of high-Tc superconductors have been carried out by G. J. Schmitz et al. (ACCESS, Aachen). The authors performed macroscopic-scale calculations of the temperature field in bulk YBCO during melt growth, and used the phase-field method to do mesoscopic simulations of microstructure evolution. The authors also discuss implications for enhanced production rates for YBCO in bulk or tape form.
Bi Cuprates
A preprint by Ch. Renner et al. (Geneva) reports local-probe tunneling spectroscopy of Bi2Sr2CaCu2O8+d (Bi-2212) single crystals for different oxygen concentrations, from optimally doped (Tc = 92.2 K) to highly overdoped (Tc = 56.0 K) phases. With increasing oxygen overdoping, the superconducting gap Delta_p is reduced and the dip structure beyond Delta_p at negative sample bias shifts toward the Fermi energy. Apart from these changes, the generic shape of the tunneling spectra remains unchanged. The gap roughly scales with Tc, and 2Delta_p/k_BTc stays large even in the highly overdoped phase. The authors also present preliminary results on the temperature dependence of the tunneling spectra. They are consistent with a gap that is temperature-independent up to the vicinity of Tc.
As shown by C. J. van der Beek (Argonne) et al., magnetic-screening effects of the geometrical barrier in Bi-2212 single crystals can be suppressed by the application of a sufficiently large ac field. This procedure allows the onset of strong bulk flux pinning to be observed. The authors found that this occurs at T ~~ 40 K, independent of whether the field strength is above or below the field of the second peak in the magnetization.
Comparative studies on a Bi-2212 single crystal, a Ag/Bi-2212 tape, and a Ag/Bi-2223 tape have been carried out by S. X. Dou et al. (Wollongong). The authors found that the irreversibility line for the Ag/Bi-2223 tape is at higher temperatures than that for the Ag/Bi-2212 tape, which in turn is higher than that for the Bi-2212 single crystal. The authors also were able to show that defects induced by mechanical deformation act as pinning centers in the tapes and are thus responsible for the improvement in flux pinning.
A preprint by A. Oota and M. Tanaka (Toyohashi University of Technology) reports measurements of the transport critical current density Jc(T,B,theta) of screen-printed, c-axis-oriented (Bi,Pb)2Sr2Ca2Cu3O10+d/Ag composite tape with a ceramic monolayer core at T = 4.5-77 K in magnetic fields B up to 8 T as a function of the angle theta between B and the c axis. At low temperatures (T <= 30 K), a shift of the peak angle from theta = 90 degrees occurred in the Jc vs. theta curve, accompanied by an additional asymmetry. The authors explain these anomalies in terms of the history effect in Jc vs. B due to grain-boundary weak links, using the assumption that Jc is dominated by the field component B_[parallel] = B cos -theta parallel to the c axis. At elevated temperatures, the authors found that the history effect disappeared and that Jc had a perfectly symmetrical angular dependence with a peak at theta = 90 degrees.
Scanning electron microscopy (SEM), energy-dispersive x-ray analysis (EDX, including x-ray dot mapping), x-ray diffraction (XRD), and computer-based image analysis have been used by N. N. Merchant (Argonne) et al. to study nonsuperconducting secondary phases that evolve during the processing of (Bi,Pb)2Sr2Ca2Cu3O10+d/Ag composite conductors. The authors identified (Ca,Sr)2CuO3, (Ca,Sr)14Cu24)41, CuO phases, the alkaline-earth plumbates, and a (Bi,Pb)-Sr-Ca-Cu-O 3221 phase with a wide range of Pb/Bi ratios. These techniques help to differentiate voids from secondary phases, and alkaline-earth plumbates from the leadrich 3221 phase.
As reported by A. Sotelo (MPI, Stuttgart) et al., the use of a new process based on detailed phase-diagram studies of the system Bi2O3-PbOSrO-CaO-CuO results in the formation of nearly single-phase (Bi,Pb)2Sr2Ca2Cu3O10+d (2223) ceramics. Different mixtures of defined precursor were prepared and studied to overcome the very slow kinetics of the reaction forming 2223. The best results were obtained with mixtures of Bi1.84Pb0.34Sr1.8Ca1.2Cu2O8, Ca2CuO3, and CuO, and Bi1.84Pb0.34Sr1.7Ca1.3Cu2O8, Sr0.2Ca1.8CuO3, and CuO.
Other Cuprates
The frequencies and phonon-mode displacement patterns of the Brillouinzone-center phonons for Tl2Ba2CaCu2O8+d (Tl-2212) have been determined by C.-S. Jia (Nanchong) et al. The calculations were carried out in the framework of a simple force-constant model that includes nearestneighbor and next-nearest-neighbor interactions. The ten adjustable parameters were obtained by fitting Raman and infrared measurements.
The growth of high-quality HgBa2CuO4+d (Hg-1201) single crystals of submillimeter size is reported by A. Bertinotti et al. (Saclay). The synthesis method yields as-grown crystals that are optimally doped (Tc = 94 K).
A preprint by R. Usami (Mitsubishi, Kanagawa) et al. reports the magnetization and microstructure of a grain-aligned sample of HgBa2Ca2Cu3O8+d (Hg-1223) and a lesser amount of HgBa2CaCu2O6+d (Hg1212) before and after irradiation by 4.0 MeV protons at a dose of 5 x 10^[16] cm^[-2]. Magnetization hysteresis measurements showed that proton irradiation introduced pinning centers, and x-ray diffraction and TEM studies revealed amorphous defects within irradiated grains.
Neutron-diffraction measurements of magnetic scattering in La1.6xNd0.4SrxCuO4 with x = 0.15 and 0.20 have been carried out by J. M. Tranquada (Brookhaven) et al. The authors present evidence that superconductivity and charge-stripe order coexist in this material, although the order parameters compete with each other. For a given x, the spatial modulation of the spin correlations is the same as in La2xSrxCuO4, which indicates that the instantaneous correlations are essentially the same in the two systems. The authors suggest that there is an intimate connection between stripe correlations and superconductivity in these materials.
Vortices
A phase diagram for the vortex structure of high-temperature superconductors incorporating the effects of anisotropy and disorder is proposed in a preprint by E. A. Jagla and C. A. Balseiro (Bariloche). It is based on numerical simulations using the three-dimensional Josephson-junction-array model. The authors support these results with estimates of the internal energy and configurational entropy of the system. The results give a unified picture of the behavior of the vortex lattice, from the highly anisotropic material Bi2Sr2CaCu2O8+d (Bi-2212) to the less anisotropic YBa2Cu3O7-d (Y-123), and from firstorder melting in clean samples to the continuous transitions observed in samples with defects.
A framework for the analysis of magnetization data on high-temperature superconductor crystals that allows direct comparison with vortex pinning theory has been established by G. K. Perkins and A. D. Caplin (Imperial). The authors report that when the magnetization loops exhibit scaling behavior, as they do over a large part of the B-T plane for RBa2Cu3O7-d (R = rare earth), the effective pinning energy U_[eff] must contain power-law field dependencies for the characteristic energy and current scales U_0 and J_0. These power-law exponents can be obtained directly from the data. The authors find that many regimes of collective-pinning (CP) theory do predict such power laws, but none yield exponents in agreement with those that are measured. The discrepancy appears to arise because U_0 is observed to decrease with B, in contrast to the CP predictions.
A preprint by H. Safar (Illinois-Chicago) et al. reports that twin boundaries are one of the most important sources of pinning in thick YBCO films. The authors demonstrate that they induce a Bose-glass transition with the predicted cusp behavior in the glass transition temperature. From angular scaling of the temperature-dependent linear resistivity and nonlinear current-voltage characteristics, the authors obtained the values nu = 1.3+-0.1 and z = 6.2+-0.3 for the critical exponents.
A theory for the ac response of a vortex array in inhomogeneous superconductors has been developed by M. Ziese (Leipzig). The author reports that the flux-line response at small driving currents is linear in the Lorentz force and that it can be mapped on impedance networks. Critical exponents and scaling functions for the three-dimensional percolation problem are calculated and found to be in good agreement with experimental data in twinned YBCO crystals.
Simulations of B(x,y,H), M(H), and Jc(H) in a time-varying applied field H for a variety of twin-boundary pinning-potential parameters and for a range of values of the density and strength of pinning sites are reported by J. Groth et al. (Michigan). The authors numerically solve the overdamped equations of motion of up to 10^4 flux-gradient-driven vortices, which can be temporarily trapped at ~10^6 pinning centers. These simulations relate macroscopic measurements [e.g., M(H) and flameshaped B(x,y) profiles] with the underlying microscopic pinning landscape and the dynamics of individual vortices.
A related preprint by C. Reichhardt et al. (Michigan) reports simulations of flux-gradient-driven rigid vortices interacting with square and triangular arrays of columnar pinning sites in an increasing external magnetic field. The authors observed a variety of evolving complex flux profiles, including flat terraces or plateaus separated by winding current-carrying strings and, near the peaks in the magnetization M(H), plateaus only in certain regions, which move through the sample as the field increases.
A theory for the decay of supercurrent through nucleation of vortexantivortex pairs in a two-dimensional superconductor in the presence of dissipation and a periodic pinning potential has been developed by R. Iengo (Trieste) and G. Jug (Como and Pavia). The authors use a quantum electrodynamics formulation to show that the current-density dependence of the nucleation rate develops oscillations that are connected to the pinning periodicity.
The coupled nonlinear electrodynamics of an isotropic, ultraclean typeII superconductor has been examined by M. W. Coffey (Colorado). A theory for weakly nonlinear but strongly dispersive wave propagation in an Abrikosov vortex lattice of a high-temperature superconductor is developed. The author finds that the nonlinear Schroedinger equation governs the evolution of the complex amplitude, allowing soliton solutions.
The dynamic response of a driven vortex lattice in the presence of quenched disorder has been studied theoretically by S. Scheidl (Koeln) and V. Vinokur (Argonne). The authors propose a simple model for hysteretic creep and evaluate its behavior numerically. The results provide a qualitative explanation for some hysteresis and memory effects recently observed in current-voltage characteristics.
A preprint by A. Schoenenberger (ETH Zurich) et al. numerically investigates the dynamically generated plastic deformations of a 3D vortex lattice driven through a disorder potential with isolated strong pinning centers (point-like or extended along the field direction). The authors find that the vortex lattice exhibits a peculiar dynamical behavior in the plastic-flow regime, involving the generation of topological excitations consisting of three or four entangled vortices. The authors determine the critical current density Jc and the activation energy for depinning U_c in the presence of a finite density of strong pinning centers.
Theory
A microscopic calculation of the current and magnetic-field distribution in the mixed state of model s-wave and d-wave superconductors is reported by Y. Wang and A. H. MacDonald (Indiana). For the d-wave case, the authors find that corrections to London theory are important at fields small compared with H_[c2]. The field distribution is influenced by both superfluid-velocity dependence and nonlocality in the currentresponse function of the mixed state. The authors compare their results with recent muon-spin-rotation (muSR) measurements in high-temperature superconductors.
A preprint by P. J. Hirschfeld (Florida) et al. reports calculations of the c-axis infrared conductivity sigma_c for a d_[x^2-y^2]-wave superconductor including both elastic impurity and inelastic spinfluctuation scattering. The authors compare these results with the abplane conductivity sigma_[ab] in the same model. While inelastic scattering in clean systems leads to a peak in sigma_[ab] at omega = 4Delta_0 for T < Tc, it has little effect on the corresponding sigma_c, which exhibits structure only at omega ~~ 2-Delta_0. The c-axis penetration depth lambda_c in the same model is predicted to vary as T^3 at low temperatures in clean samples.
Using the composite-operator method, T. Di Matteo (Salerno) et al. show that the 2D single-band Hubbard model exhibits a superconducting solution. In particular, the authors consider singlet pairing and show that both s-wave and d-wave symmetries are possible solutions of the model. The authors present calculations of the order parameters and critical temperatures as functions of the interaction strength and carrier density.
In a related paper, A. Avella (Salerno) et al. report a study of the Ut-t' model using the composite-operator method. The effect of the bare diagonal hopping term t' is analyzed in detail. The results show good agreement with those obtained by Monte Carlo methods.
A preprint by M. Cini and A. Balzarotti (Roma) reports on the electronic properties of Cu5O4. The results support the view that the electronic properties of small clusters depend crucially on the symmetry. Previous results on CuO4 pointing to an effective attraction between holes are confirmed, and the singlet-triplet separation stabilizes around 40 meV in a wide range of parameters.
Measurements in 1980 by Van Harlingen showed that the flux induced by a temperature difference between the two junctions of a Pb-In ring exceeded theoretical expectations by about five orders of magnitude. A preprint by D. C. Marinescu and A. W. Overhauser (Purdue) now reports the development of an electron-conserving transport theory that explains the data.
A preprint by D. Agassi and J. R. Cullen (NSWC, White Oak) reports calculations of the current-phase relation in a superconducting-normal superconducting (S-N-S') junction, in which the N-layer thickness is of the order of the metallic screening length (~1-2 Angstroms). A gap state contributes an appreciable sin2-phi correction term to the usual sin-phi Josephson term. The authors predict corresponding deviations from the usual behavior of superconducting quantum interference devices (SQUIDs).
Thin Films
As reported by K. Verbist (Antwerp) et al., the use of a diluted O2/Ar atmosphere for laser deposition of YBa2Cu3O7-d thin films results in a strong decrease of the surface outgrowth density compared with deposition in pure O2. The smoother films need a longer oxygenation period and show slightly lower critical current densities, though still in excess of 10^6 A/cm^2 at 77 K. Electron microscopy revealed that the outgrowths consist mainly of large copper-oxide grains connected to Y2O3 grains. Y2O3 nanoscale inclusions are present irrespective of the deposition atmosphere, but at much lower densities than reported previously. The authors find that the twin-plane density is lower and the twin structure more homogeneous for the films deposited in the O2/Ar mixture. The authors ascribe this to the absence of surface outgrowths, which seem to block regular twin-structure formation.
An ion-gettering effect is reported by S. H. Hong (Columbia) et al. in YBa2Cu3O7-d after implantation by Si ions. Upon high-temperature annealing, the Si ions moved against the diffusion direction and increased their density in a high-concentration region, where damage to the YBCO crystal structure is severe. The authors suggest that this ion-gettering effect could be used to make a superconductornonsuperconductor-superconductor trilayer structure within a single YBCO film.
A preprint by S. Awaji et al. (Tohoku) reports measurements of the irreversibility field B_i and transport critical current density Jc for two YBa2Cu3O7-d films with different pinning strengths in fields up to 27 T. The normalized pinning force density F_p/F_p^[max] vs. normalized field B/B_i at different temperatures shows good scaling at temperatures below about 60 K. The peak position of F_p/F_p^[max] occurs at B/B_i ~~ 0.1 for both samples. Using this relation, the authors estimated the B_i values (30-120 T) at temperatures too low for B_i to be measured directly. The obtained B_i behavior follows a power-law dependence, (1T/Tc)^[1.5], at high temperatures and low fields and then increases rapidly with temperature at temperatures below about 50 K.
Measurements of the critical current densities of Tl-2212 and Tl-2223 thin films, grown by sputtering and post annealing on LaAlO3, as a function of the angle theta between the magnetic field and the c axis at various temperatures and magnetic fields are reported by G. S. Hosseinali (Atominstitut-Wien) et al. The results show higher critical current densities in Tl-2223 than in Tl-2212 at low temperatures. The authors also found Jc to be strongly field dependent in both films, indicating weak-link effects. Scaling of Jc^[ab](theta) with the c-axis component of the applied field was observed at all temperatures in both films, suggesting 2D nature of the flux lines. The effect of fastneutron and Au-ion irradiation was investigated for both films. Large enhancements of flux pinning and Jc were observed, especially at high temperatures, without significant changes of Tc.
Applications
Results from sodium-magnetic-resonance-imaging experiments using hightemperature superconducting (HTS) receiver coils are reported by J. R. Miller (Columbia) et al. Sodium imaging has been shown to have great potential for the assessment of cell integrity but suffers from a substantially lower signal-to-noise ratio (SNR) than that of hydrogen imaging. The authors found that the use of a receiver coil fabricated from a Tl2Ba2CaCu2O8+d (Tl-2212) film (Tc = 105 K) on a LaAlO3 substrate and operated at 40 K produced a tenfold increase in the SNR relative to the performance of an equivalent copper receiver coil at room temperature. The SNR gains afforded by HTS coils can also be used to decrease the imaging time.
A preprint by K. Fukushima (Hitachi) et al. reports the fabrication of a solenoidal coil without joints, employing silver-sheathed Bi-2212 multifilamentary tapes, by the wind-and-react process. Alumina cloth tapes were wound together with the Bi-2212/Ag tapes to insulate the coil. At 4.2 K (in liquid He), the coil exhibited overall current densities of 8.19 x 10^3 A/cm^2 and 2.83 x 10^3 A/cm^2, and generated magnetic fields of 1.42 T and 0.50 T in backup fields of 0 T and 21 T, respectively.
A continuous process for the fabrication of advanced, semi-finished YBa2Cu3O7-d (YBCO) parts and products for superconducting magnetic bearings is reported by H. J. Bornemann et al. (Karlsruhe). Highquality YBCO bulk components are produced powder metallurgically by sintering and partial melting of precursor powders. Depending on size, shape, tolerances, and levitation requirements, parts are either diepressed or precision-machined from isostatically pressed blocks. The oxygenation process can be monitored in-situ by a macro-
thermogravimetric analyzer. Frictionless bearing modules have been manufactured in various sizes ranging from 40 mm to 140 mm in diameter. Lifting forces are up to 200 N per bearing module. The authors foresee applications for these bearings in high-speed machinery, cryogenic systems, gyroscopes, transportation systems, and vibration isolation.
Other Activities
The superconducting plasma resonance along the c axis in the farinfrared region has been observed by H. Shibata and T. Yamada (NTT, Kanagawa) in various high-Tc cuprates, including electron-doped and Bi cuprates. The authors demonstrate that an alternative to reflectivity measurements in single crystals is the sphere resonance of powder samples, since it is sensitive only to the c-axis dielectric constant in the far-infrared region. The authors report measurements, extending down to 7.5 cm^[-1], showing the resonance in Bi1.85Pb0.35Sr2Ca2Cu3.1O10+d, La1.82Ca1.18Cu2O6+d,
(Nd0.66Sr0.205Ce0.135)2CuO4, (Ba0.56Sr0.44)2Cu1.1O2.2+d(CO3)0.9, Pr1.85Ce0.15CuO4, and Nd2CuO4-xFx, but not in Bi2Sr1.6La0.4CuOy and Bi2Sr2CaCu2O8+d. The authors discuss the resonance frequencies using the Josephson-coupled-layer model, and they estimate the c-axis penetration depth lambda_c from the resonance frequencies.
Using Raman scattering, T. Strach (MPI, Stuttgart) et al. have measured the energies and intensities of crystal-field (CF) transitions in Nd2CuO4 and Sm2CuO4 at low temperature in magnetic fields up to 16 T. The experimental results are found to be in good agreement with theoretical calculations of the CF energy levels using a single-ion Hamiltonian that includes the CF potential, the rare-earth-Cu exchange interaction and a Zeeman term.
The effective microwave surface resistance of superconductor/dielectric/normal-metal structures has been analyzed by E. Silva et al. (Roma) using numerical simulations. The authors test the model by doing surface-resistance measurements on a Bi- 2212/SrTiO3/metal structure.
The nonmonotonic magnetic-field dependence of the nonresonant microwave absorption in YBa2Cu3O7-d/CuO ceramic composite samples is explained by A. Anand et al. (Bangalore) in terms of a resistively shunted junction (RSJ) model including junctions whose phase differences are in the range pi/2 to 3pi/2.
According to a preprint by H. A. Blackstead (Notre Dame) et al., their charge-reservoir-oxygen model of superconductivity predicts for Sm1.5Ce0.5Sr2Cu2NbO10 that: (a) Tc ~~ 30K vs. the observed Tc ~~ 28 K, (b) roughly 1% Ni on Cu sites should drive Tc to zero, (c) superconductivity originates in the SrO layers, not in the CuO2 layers, and (d) the conduction in this material and in all high-Tc oxide superconductors is p-type. The model also explains why this material can superconduct in the presence of the magnetic rare-earth ion Sm, and why Gd on Sm sites does not destroy superconductivity, despite structural similarities to Sm2-zCezCuO4 and Gd2-zCezCuO4, although the former superconducts and the latter does not.
A reentrant behavior of the peak effect, for H parallel to c and to a, in very clean single crystals of the anisotropic superconductor 2H-NbSe2 (Tc = 7.1 K) has been observed by S. Ramakrishnan (TIFR, Bombay) et al. A plot of the position of the peak effect on an H-T (field-temperature) plot resembles the predicted vortex-lattice melting curve (with a nose near Tc) for anisotropic superconductors. The authors also stress that the disappearance of the peak effect at low fields is consistent with the expected crossover to a disordered state when the intervortex spacing far exceeds the penetration depth.
Overviews
Experiments designed to ascertain the percolative nature of current flow in high-critical-current-density (Jc) polycrystalline superconductors are reviewed in a preprint by A. Goyal (Oak Ridge) et al. The authors find a direct correlation between the grain-orientation texture and the current transport in high-Jc TlBa2Ca2Cu3O9 (Tl-1223) thick films and Bi2Sr2Ca2Cu3O10+d (Bi-2223) powder-in-tube tapes. Magneto-optical visualization of the current flow in the same regions confirmed the percolative nature of current flow. Numerical modeling of the current flow based on the observed grain-boundary-character distribution and the effects of grain-boundary misorientation angle on Jc was found to predict the percolative nature of current flow. These studies indicate that to increase Jc further, increased fractions of small-angle boundaries are required. The authors suggest that this is an appropriate research direction for the next generation of hightemperature-superconducting wire (29 refs.).
A brief review of work at Varian on the use of atomic layer-by-layer molecular-beam-epitaxy (ALL-MBE) growth of cuprate superconductors and other complex oxides has been prepared by I. Bozovic and J. N. Eckstein. The authors give new details on the SIS HTS tunnel junctions they make. They use Bi-1278, an artificial metastable HTS compound that can be synthesized by ALL-MBE, and in the central layer, the authors replace Ca by Dy. This provides for a virtually perfect and rather thin insulating barrier layer, which is one of the key requirements for the fabrication of SIS junctions with HTS cuprates. These junctions exhibit significant Josephson supercurrents and very sharp quasiparticle tunneling I-V characteristics. At 4.2 K, the differential conductance shows a deltafunction-like peak at about 50 mV. At elevated temperatures, the peak broadens and shifts to lower energies. The temperature dependence of the gap voltage may be fitted to a power law, similar to what has been observed in native Josephson junctions in Bi-2212 single crystals (17 refs.).
Contributed by John R. Clem
High-Tc Update is available without charge to interested persons. Recipients are expected to participate in this information exchange by sending us preprints, reprints, meeting news, research news, etc. Contributions to defray the cost of newsletter printing and mailing are welcome.
D. Agassi and J. R. Cullen, "Current-Phase Relation in an Intermediately Coupled Superconductor-Superconductor Junction." Naval Surface Warfare Center, White Oak, MD 20903-5640; telefax (301) 394-5135.
A. Anand, Amit Rastogi, M. S. Hegde, and S. V. Bhat, "'Phase Reversal' of Non-Resonant Microwave Absorption in Superconducting YBaCuO/CuO Powder Mixtures." To be published in Solid State Commun. Department of Physics, Indian Institute of Science, Bangalore 560012, INDIA; e-mail anandi@physics.iisc.ernet.in. Key words: superconductors, chemical synthesis, Josephson junctions, microwave dissipation and non-resonant microwave absorption.
F. B. Anders and K. Gloos, "Towards a Microscopic Theory for Metallic Heavy-Fermion Point Contacts." Department of Physics, Ohio State University, Columbus, OH 43210-1106; e-mail anders@pacific.mps.ohiostate.edu; preprint also available at supr-con@xxx.lanl.gov (#9607007).
Hidehito Asaoka, Yukio Kazumata, Humihiko Takei, and Kenji Noda, "Effect of Twin Boundaries on Flux Pinning in YBa2Cu3Ox Single Crystals." To be published in Physica C (in press). Japan Atomic Energy Research Institute, Tokai-mura, Naka-gun, Ibaraki 319-11, JAPAN. Key words: flux pinning, critical current density, twin boundaries, SQUID, YBa2Cu3Ox, single-crystal growth.
Adolfo Avella, Ferdinando Mancini, Hideki Matsumoto, and Dario Villani, "Local Properties in the Two-Dimensional U-t-t' Model." Submitted to the Int. Conf. on Strongly Correlated Electron Systems (SCES'96), Zurich, Switzerland, Aug. 19-22, 1996; to be published in Physica B. Contact Ferdinando Mancini, Dipartimento di Fisica Teorica e S.M.S.A., Unita INFM di Salerno, Universita di Salerno, I-84081 Baronissi (SA), ITALY; telephone +39 89 965 322; telefax +39 89 965 275; e-mail mancini@vaxsa.csied.unisa.it. Key words: Hubbard model, high-Tc superconductivity, composite operator method.
Satoshi Awaji, Kazuo Watanabe, Norio Kobayashi, Hisanori Yamane, and Toshio Hirai, "Irreversibility Field and Flux Pinning for YBa2Cu3O7 Films." To be published in the Proc. of the Eighth Int. Workshop on Critical Currents in Supercond., (8th IWCC), Kitakyushu, Japan, May 2729, 1996. Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-77, JAPAN; telephone +81 22 215 2148; telefax +81 22 215 2149; e-mail f22124@cctu.cc.tohoku.ac.jp.
Leon Balents, M. Cristina Marchetti, and Leo Radzihovsky, "Comment on 'Moving Glass Phase of Driven Lattices.'" Institute for Theoretical Physics, University of California, Santa Barbara, CA 93106-4030; preprint also available at cond-mat@xxx.lanl.gov (#9608009). 74.60.Ge.
A. Bertinotti, V. Viallet, D. Colson, J.-F. Marucco, J. Hammann, G. Le Bras, and A. Forget, "Synthesis, Crystal Structure and Magnetic Properties of Superconducting Single Crystals of HgBa2CuO4+d." To be published in Physica C (in press). CEA-Saclay, Service de Physique de l'Etat Condense, DRECAM/SPEC, F-91191 Gif sur Yvette Cedex, FRANCE; telefax +33 1 690 88786; e-mail colson@amoco.saclay.cea.fr. Key words: synthesis, single-crystal growth, structure, magnetic susceptibility.
Howard A. Blackstead, John D. Dow, and D. B. Pulling, "Theory of Sm1.5Ce0.5Sr2Cu2NbO10: Critical-Temperature and Doping Effects." To be published in J. Supercond. Department of Physics, University of Notre Dame, Notre Dame, IN 46556; telephone (219) 631-7078; telefax (219) 6315952; e-mail blackstd@rems1.phys.nd.edu. 74.20.Fg.
Hans J. Bornemann, Thomas Burghardt, Wolfgang Hennig, and Axel Kaiser, "Semi-Finished Parts and Products Made from Melt-Textured Bulk YBCO Materials for Superconducting Magnetic Bearings." Presented at the Applied Superconductivity Conference, Pittsburgh, PA, Aug. 25-30, 1996; submitted to IEEE Trans. on Appl. Supercond. FZK, INFP, Postfach 3640, D-76021 Karlsruhe, GERMANY; telephone +49 7247 82 4389; telefax +49 7247 82 4624; e-mail hb@infp.fzk.de.
Ivan Bozovic and J. N. Eckstein, "Atomic-Level Engineering of Cuprates and Manganites." Submitted to Appl. Surface Sci. Varian Research Center, 3075 Hansen Way, M/S K-114, Palo Alto, CA 94304-1025; telephone (415) 424-6358; telefax (415) 424-6988; e-mail ivan.bozovic@grc.varian.com.
V. Chakravarthy and A. M. Guloy, "Synthesis and Structure of a New Layered Organic-Inorganic Compound Containing Unique Chains of Pbl2." Preprint #96:092; submitted to J. Am. Ceram. Soc. Texas Center for Superconductivity, University of Houston, Houston, TX 77204-5932; telephone (713) 743-8200; telefax (713) 743-8201; e-mail preprints@www.tcs.uh.edu.
Michele Cini and Adalberto Balzarotti, "Symmetry-Induced Correlation Effects and Hole Pairing in the Cu5O4 Model Cluster." Submitted to Solid State Commun. INFM, Dipartimento di Fisica, Universita di Roma Tor Vergata, Via Della Ricerca Scientifica 1, I-00133 Roma, ITALY. 74.72.-h; 31.20.Tz; 74.20.-z.
Mark W. Coffey, "Hall Force-Dominated Nonlinear Dynamics of Ultraclean High-Temperature Superconductors." To appear in Phys. Lett. A. Department of Chemistry and Biochemistry, Campus Box 215, University of Colorado, Boulder, CO 80309. Key words: vortex dynamics, nonlinear Schroedinger equation, nonlocal interaction, London theory, multiple scales analysis, solitons. 41.20.Jb; 03.40.Kf; 74.60.Ge; 74.20.De.
K. Conder and Ch. Krueger, "Low Temperature (<325^oC) Chemical Diffusion of Oxygen in the Orthorhombic YBa2Cu3O6+x." To be published in Physica C. Laboratorium fuer Festkoerperphysik, ETH-Hoenggerberg, CH-8093 Zurich, SWITZERLAND; telephone +41 1 633 2239; telefax +41 1 633 1072; e-mail conder@solid.phys.ethz.ch.
P. Dai, M. Yethiraj, H. A. Mook, T. B. Lindemer, and F. Dogan, "Magnetic Dynamics in Underdoped YBa2Cu3O7-x: Direct Observation of a Superconducting Gap." Oak Ridge National Laboratory, Oak Ridge, TN 37831-6393.
M. Daturi, M. Ferretti, E. A. Franceschi, and M. Minguzzi, "Enthalpy Measurements on Nd2-xCexCuO4 under Oxygen Pressure and Thermodynamic Potentials Calculation." To be published in Physica C (in press). Contact M. Ferretti, INFM and Dipartimento di Chimica e Chimica Industriale, Universita di Genova, Via Dodecaneso 31, I-16132, Genova, ITALY; telefax +39 10 362 8252; e-mail ferretti@chimica.unige.it. Key words: electron-doped superconductors, phase diagram, pressure effect, thermal analysis, thermodynamic potentials.
Tiziana Di Matteo, Ferdinando Mancini, Hideki Matsumoto, and Viktor S. Oudovenko, "Singlet Pairing in the 2D Hubbard Model." Presented at the Int. Conf. on Strongly Correlated Electron Systems (SCES'96), Zurich, Switzerland, Aug. 19-22, 1996; to be published in Physica B. Contact Ferdinando Mancini, Dipartimento di Fisica Teorica e S.M.S.A.-Unita INFM di Salerno, Universita di Salerno, I-84081 Baronissi (SA), ITALY; telephone +39 89 965 322; telefax +39 89 965 275; e-mail mancini@vaxsa.csied.unisa.it. Key words: Hubbard model, superconductivity, singlet pairing.
S. X. Dou, J. Horvat, M. Ionescu, and H. K. Liu, "Irreversibility Behavior of Different Types of Bi-(Pb)-Sr-Ca-Cu-O Superconductors." Centre for Superconducting and Electronic Materials, University of Wollongong, Wollongong, NSW 2522, AUSTRALIA.
Keiji Fukushima, Michiya Okada, Kazuhide Tanaka, Hitoshi Kitaguchi, Hiroaki Kumakura, Kazumasa Togano, Tsukasa Kiyoshi, and Kiyoshi Inoue, "Fabrication and Transport Properties of a Solenoidal Coil Wound with Bi2Sr2CaCu2Ox/Ag Multifilamentary Tapes for High Magnetic Field Generation." To be published in Physica C (in press). Hitachi Research Laboratory, Hitachi, Ltd., 7-1-1 Omika-cho, Hitachi, Ibaraki 319-12, JAPAN. Key words: solenoidal coil, Bi-2212, W & R process, multifilamentary tape, powder-in-tube.
A. Goyal, E. D. Specht, D. K. Christen, D. M. Kroeger, A. Pashitski, A. Polyanskii, and D. C. Larbalestier," Percolative Current Flow in High-Jc Polycrystalline High Temperature Superconductors." To be published in J. Metals, Minerals, and Materials, Sept. 1996. Metals and Ceramics Division, Oak Ridge National Laboratory, P.O. Box 2008, MS 6116, Oak Ridge, TN 37831; telephone (423) 574-1587; telefax (423) 574-7659; email zag@ornl.gov.
J. Groth, C. Reichhardt, C. J. Olson, Stuart Field, and Franco Nori, "Vortex Motion in Twinned Superconductors: Magnetic Flux Density, Magnetization, and Critical Currents." Submitted to Phys. Rev. Lett.; preprint also available at cond-mat@xxx.lanl.gov (#9607182). Department of Physics, University of Michigan, Ann Arbor, MI 48109-1120. 74.60.Ge.
P. J. Hirschfeld, S. M. Quinlan, and D. J. Scalapino, "c-Axis Infrared Conductivity of a d_[x^2-y^2]-Wave Superconductor with Impurity and Spin-Fluctuation Scattering." Submitted to Phys. Rev. B. Department of Physics, University of Florida, Gainesville, FL 32611. 74.25.Nf; 74.72.-h; 72.10.Di; 72.10.Fk.
S. H. Hong, M. L. Chen, J. Baniecki, Q. Y. Ma, H. A. Wang, and R. W. Odom, "Observation of Ion Gettering Effects in High Temperature Superconducting Oxide Material. To be published in Appl. Phys. Lett., Sept. 1996. Department of Electrical Engineering, Columbia University, 1321 Mudd Bldg., New York, NY 10027; telephone (212) 854-4248; e-mail shhong@ctr.columbia.edu. 74.60.mj; 74.75.+t.
G. Samadi Hosseinali, W. Straif, B. Starchl, K. Kundzins, H. W. Weber, S. L. Yan, M. Manzel, E. Stangl, S. Proyer, D. Baeuerle, and E. Mezzetti, "Critical Currents in TI-2212 and TI-2223 Thin Films." To be published in Physica C (in press). Atominstitut der OEsterreichischen Universitaeten, A-1020 Wein, AUSTRIA; telefax +43 1 72701 240; e-mail weber@ati.ac.at. Key words: thin films, sputtering, STM, neutron irradiation, ion irradiation, 2D model, non-oriented terraces.
N. H. Hur, M. Paranthaman, J. R. Thompson, and D. K. Christen, "Superconductivity in the Indium-Doped Tl-1223 Phase: (Tl0.8In0.2)(Sr0.8Ba0.2)2Ca2Cu3O9-d." To be published in Physica C (in press). Korea Research Institute of Standards and Science, P.O. Box 102, Yusong, Taejon 305-600, REPUBLIC OF KOREA; telefax +82 42 868 5022; e-mail nhhur@krissol.kriss.re.kr.
Roberto Iengo and Giancarlo Jug, "Microscopic Oscillations in the Quantum Nucleation of Vortices Subject to Periodic Pinning Potential in a Thin Superconductor." International School for Advanced Studies, Via Beirut 4, I-34014 Trieste, ITALY. 74.60.Ge; 74.20.-z; 03.70.+k.
Y. Imagawa and Y. Shiohara, "Effect of Precursor Processing on Refinement of Y2BaCuO5 in Melt-Processed YBa2Cu3O6+x by Unidirectional Solidification." To be published in Physica C (in press). Superconductivity Research Laboratory, International Superconductivity Technology Center (ISTEC), 10-13 Shinonome 1-chome, Koto-ku, Tokyo 135, JAPAN; telephone +81 3 3536-5711; telefax +81 3 3536-5717. Key words: directional solidification, YBCO, high Jc, Y211 size.
Valery Ivanov and Kazushi Kanoda, "Strong Electron Correlations in kappa-(BEDT-TTF)2X Salts." To be published in Physica C (in press). Institute for Molecular Science, Nishigonaka 38, Myodaiji-cho, Okazaki 444, JAPAN. Key words: Coulomb interactions, band structure, anisotropic superconductor, organic superconductor.
E. A. Jagla and C. A. Balseiro, "The Phase Diagram of High-Tc's: Influence of Anisotropy and Disorder." Submitted to Phys. Rev. B. Comision Nacional de Engergia Atomica, Centro Atomico Bariloche and Instituto Balseiro, 8400 San Carlos de Bariloche, ARGENTINA; e-mail jagla@cab.cnea.edu.ar; preprint also available at cond-mat@xxx.lanl.gov (#9607219). 74.25.Dw; 74.60.Ge; 74.50.+r.
Chun-Sheng Jia, Pi-Yuan Lin, Yang Xiao, Xiao-Wei Jiang, Xue-Yan Gou, Su Huo, Hao Li, and Qiu-Bo Yang, "Lattice Dynamics Study of Tl2Ba2CaCu2O8 High-Temperature Superconductor." To be published in Physica C (in press). Contact Pi-Yuan Lin, Department of Computer Science, Southwest Petroleum Institute, Nanchong 637001, PEOPLE'S REPUBLIC OF CHINA.
Ali E. Khalil, "The Inversion of Meissner Effect and Granular Disorder in Bi2Sr2CaCu2O8+d Superconductors." Submitted to Phys. Rev. B. Department of Physics, University of Bahrain, P.O. Box 32038, BAHRAIN.
T. Kluge, G. Jakob, M. Speckmann, C. Tome-Rosa, and H. Adrian, "Scattering Phase Shifts in Ni and Zn Doped Y-123." To be published in J. Low Temp. Phys.: Proc. of the Int. Conf. on Phys. and Chem. of Molecular and Oxide Supercond. (MOS'96), Karlsruhe, Germany, Aug. 2-6, 1996. Institut fuer Physik, Staudingerweg 7, D-55099 Mainz, GERMANY. 74.62.Dh.
R.T.W. Koperdraad and A. Lodder, "Predictions About the Proximity Effect in a NbN/YHx Bilayer." To be published in Physica C (in press). Faculteit Natuurkunde en Sterrenkunde, Vrije Universiteit, De Boelelaan 1081, 1081 HV Amsterdam, THE NETHERLANDS.
Hee-Gyoun Lee, Il-Hyun Kuk, and Gye-Won Hong, "Non-Uniform Phase Transition in a YBa2Cu3O7-d Bulk Superconductor." To be published in J. Mater. Sci. Lett. Superconductivity Research Laboratory, Korea Atomic Energy Research Institute, P.O. Box 105, Yusung-gu, Taejon 305-600, KOREA; telephone +82 42 868 8024; telefax +82 42 862 5496; e-mail hglee@nanum.kaeri.re.kr.
T. B. Lindemer and E. D. Specht, "Nonstoichiometry and Decomposition of Pr1+zBa2-zCu3Oy and Comparison with Y123, La123 and Nd123." To be published in Physica C (in press). Chemical Technology Division, Oak Ridge National Laboratory, Post Office Box 2008, Oak Ridge, TN 378316221; telefax (615) 574-6872; e-mail lin@ornl.gov.
Ferdinando Mancini, Hideki Matsumoto, and Dario Villani, "Dynamical Spin Magnetic Susceptibility in the 2D Hubbard Model." Presented at the XXI Int. Conf. on Low Temperature Phys. (LT21), Prague, Czech Republic, Aug. 8-14, 1996; to be published in Czech. J. Phys. Dipartimento di Fisica Teorica e S.M.S.A. e Unita INFM di Salerno, Universita di Salerno, I84140 Baronissi (SA) ITALY.
Ferdinando Mancini, Viktor Oudovenko, and Dario Villani, "Magnetic Properties of the Two-Band Singlet-Hole Model for the Copper-Oxide Plane." Presented at the XXI Int. Conf. on Low Temperature Phys. (LT21), Prague, Czech Republic, Aug. 8-14, 1996; to be published in Czech. J. Phys. Dipartimento di Fisica Teorica e S.M.S.A. e Unita INFM di Salerno, Universita di Salerno, I-84140 Baronissi (SA) ITALY.
D. C. Marinescu and A. W. Overhauser, "Thermoelectric Flux in Superconducting Rings: A Search for a Factor of 10^5." Department of Physics, Purdue University, West Lafayette, IN 47907.
N. N. Merchant, A. K. Fischer, V. A. Maroni, W. L. Carter, and R. D. Parrella, "Identification and Quantification of Phases Formed During the Processing of (Bi,Pb)2Sr2Ca2Cu3Ox/Ag Composite Conductors." Presented at the Applied Superconductivity Conference, Pittsburgh, PA, Aug. 25-30, 1996; submitted to IEEE Trans. on Appl. Supercond. Contact Janice Coble, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439; telefax (708) 252-9595; e-mail janice_coble@qmgate.anl.gov.
J. R. Miller, K. Zhang, Q. Y. Ma, I. K. Mun, K. J. Jung, J. Katz, D. W. Face, and D. J. Kountz, "Superconducting Receiver Coils for Sodium Magnetic Resonance Imaging." To be published in IEEE Trans. on Biomedical Eng. Department of Electrical Engineering, Columbia University, 1312 Mudd Building, New York, NY 10027; e-mail jrm33@columbia.edu.
Sang Boo Nam, "Pairing Theory of High and Low Temperature Superconductors." To be published in the Proc. of the Int. Conf. on Advanced Mater. and Devices (ICAMD'96), Phoenix Park, Korea, June 11-13, 1996. 7735 Peters Pike, Dayton, OH 45414.
S. Ondono-Castillo and N. Casan-Pastor, "Deposition of YBa2Cu3O7-d over Metallic Substrates by Electrophoresis of Suspensions in Isobutylmethylketone: Influence of Electric Field, Thermal and Mechanical Treatments." To be published in Physica C (in press). Instituto de Ciencia de Materials de Barcelona, C.S.I.C., Campus U.A.B., 08193 Bellaterra, Barcelona, SPAIN; telephone +34 3 580 1853; telefax +34 3 580 5729. Key words: electrophoresis, coatings, superconductor, YBa2Cu3O7-d, oxides.
A. Oota and M. Tanaka, "History Effect and Anisotropy of Critical Current Density in Screen-Printed (Bi,Pb)2Sr2Ca2Cu3Ox/Ag Tape." To be published in Physica C (in press). Toyohashi University of Technology, Tempaku-cho, Toyohashi, Aichi 441, JAPAN; telefax +81 532 44 6732; email oota@eee.tut.ac.jp. Key words: Bi2223, history effect, critical current anisotropy, flux creep, weak link. 74.60.Jg; 74.72.Hs; 74.76.Bz; 74.60.Ge.
G. K. Perkins and A. D. Caplin, "Collective Pinning Theory and the Observed Vortex Dynamics in (RE)Ba2Cu3O7-d Crystals." To be published in Phys. Rev. B. Centre for High Temperature Superconductivity, Blackett Laboratory, Imperial College, London SW7 2BZ, UNITED KINGDOM; +44 171 594 7609; telefax +44 171 594 7580; e-mail g.perkins@ac.ic.uk. Key words: flux creep, flux pinning, magnetization, type-II superconductors.
S. Ramakrishnan, N. G. Patil, S. S. Banerjee, Subir Saha, Gautam I. Menon, A. K. Grover, P. K. Mishra, T. V. Chandrasekhar Rao, G. Ravikumar, V. C. Sahni, K. Ghosh, C. V. Tomy, G. Balakrishnan, D. McK. Paul, and S. Bhattacharya, "Reentrant Peak Effect Via Magnetization Studies in NbSe2." Presented at the XXI Int. Conf. on Low Temperature Phys. (TL21), Prague, Czech Republic, Aug. 8-14, 1996. Tata Institute of Fundamental Research, Bombay-400005, INDIA; telefax +91 22 215 2110 or -2181; N. G. Patil's e-mail pnitin@tifruax.tifr.res.in. Key words: reenterant, peak effect, thermodynamic measurements, vortex melting, 2HNbSe2.
C. Reichhardt, J. Groth, C. J. Olson, Stuart Field, and Franco Nori, "Spatio-Temporal Dynamics and Plastic Flow of Vortices in Superconductors with Periodic Arrays of Pinning Sites." To be published in Phys. Rev. B. Department of Physics, University of Michigan, Ann Arbor, MI 48109-1120; J. Groth's e-mail groth@gucho.physics.lsa.umich.edu; preprint also available at condmat@xxx.lanl.gov (#9607005). 74.60.Ge; 74.60.Jg; 74.60.Ec.
Ch. Renner, B. Revaz, J.-Y. Genoud, and O. Fischer, "Oxygen Doping and Temperature Dependence of the Tunneling Spectroscopy on Bi2Sr2CaCu2O8+d." To be published in J. Low Temp. Phys.: Proc. of the Int. Conf. on Phys. and Chem. of Molecular and Oxide Supercond. (MOS'96), Karlsruhe, Germany, Aug. 2-6, 1996. Departement de Physique da la Matiere Condensee, Universite Geneve, 24 quai Ernest-Ansermet, CH1211 Geneve 4, SWITZERLAND; telephone +41 22 702 61 11; telefax +41 22 702 68 69. 74.50.+r; 74.62.Dh; 74.72.Hs.
H. Safar, S. R. Foltyn, Q. X. Jia, and M. P. Maley, "Bose Glass Vortex Phase Transition in Twinned YBa2Cu3O7-d Superconductors." To be published in Phil. Mag. B. Superconductivity Technology Center, Los Alamos National Laboratory, Los Alamos, NM 87545.
S. Sathyamurthy, A. S. Parikh, and K. Salama, "Processing of Polycrystalline HTS for High Current Transport Applications." Preprint #96:089; submitted to Physica C. Texas Center for Superconductivity, University of Houston, Houston, TX 77204-5932; telephone (713) 743-8200; telefax (713) 743-8201; e-mail preprints@www.tcs.uh.edu.
Stefan Scheidl and Valerii Vinokur, "Hysteretic Creep of Elastic Manifolds." Submitted to Phys. Rev. Lett. Institut fuer Theoretische Physik, Universitaet zu Koeln, Zuelpicher Strasse 77, D-50937 Koeln, GERMANY. 61.20.Lc; 74.60.Ge; 74.60.Jg.
G. J. Schmitz, B. Nestler, and M. Seesselberg, "YBCO Melt-Processing Development by Numerical Simulation." To be published in J. Low Temp. Phys.: Proc. of the Int. Conf. on Phys. and Chem. of Molecular and Oxide Supercond. (MOS'96), Karlsruhe, Germany, Aug. 2-6, 1996. ACCESS e.V. Materials Sciences, Intzestrasse 5, D-52072 Aachen, GERMANY; telephone +49 241 806721; telefax +49 241 38578; e-mail gjs@gi.rwthaachen.de. 81.10.Fq; 85.40.Jq; 74.62.Bf.
A. Schoenenberger, A. Larkin, E. Heeb, V. Geshkenbein, and G. Blatter, "Strong Pinning and Plastic Deformations of the Vortex Lattice." Theoretische Physik, ETH Hoenggerberg, CH-8093 Zurich, SWITZERLAND; email andreas@itp.phys.ethz.ch; preprint also available at suprcon@xxx.lanl.gov (#9607006). 74.60.-w; 74.60.Ge.
H. Shibata and T. Yamada, "Superconducting Plasma Resonance Along the caxis in Various Copper Oxide Superconductors." To be published in Phys. Rev. B. NTT Basic Research Laboratories, 3-1 Morinosato, Wakamiya, Atsugi-shi, Kanagawa 243-01, JAPAN; telephone +81 462 40 3356; telefax +81 462 40 4675; e-mail shibata@will.ntt.jp. 74.25.Gz; 74.72.-h.
E. Silva, M. Lanucara, and R. Marcon, "Effective Surface Resistance of Superconductor/Dielectric/Metal Structures." To be published in Supercond. Sci. & Technol. Dipartimento di Fisica 'E.Amaldi', Universita degli Studi 'Roma Tre' and INFM, Via della Vasca Navale 84, I-00146 Roma, ITALY; telefax +39 6 5579303; e-mail silva@roma1.infn.it. 74.25.Nf; 74.76.Bz; 84.40.Cb.
Okram G. Singh, B. D. Padalia, Om Prakash, S. K. Agarwal, and A. V. Narlikar, "Thermoelectric Power Studies on Nd1.82-xSrxCe0.18CuOy: x<=0.18 Superconductors." To be published in J. Appl. Phys. (Oct. 15, 1996). Nuclear Science Centre, P.B. 10502, Aruna Asaf Ali Road, New Delhi 110067, INDIA; telephone +91 11 689 3955 or -2601; telefax +91 11 689 3666. 74.62.Dh; 74.72.Jt.; 74.25.Fy.
A. Soleto, P. Majewski, H.-S. Park, and F. Aldinger, "Synthesis of Highly Pure Bi-2223 Ceramics Using Defined Precursors." Submitted to Physica C. Max-Planck Institut fuer Metallforschung, Pulvermetallurgishes Laboratorium, Heisenbergstrasse 5, D-70569 Stuttgart, GERMANY.
T. Strach, T. Ruf, M. Cardona, S. Jandl, V. Nekvasil, C. Chen, B. M. Wanklyn, D. I. Zhigunov, S. N. Barilo, and S. V. Shiryaev, "Zeeman Study of Raman-Active Crystal-Field Transitions in Nd2CuO4 and Sm2CuO4." Submitted to Phys. Rev. B. Max-Planck-Institut fuer Festkoerperforschung, Heisenbergstrasse 1, D-70569 Stuttgart, GERMANY; telephone +49 711 689 1744; telefax +49 711 689 1712; e-mail strach@cardix.mpi-stuttgart.mpg.de. 74.72.Jt; 78.30.Er; 71.70.Ch.
Minoru Takemoto, Naoki Ohashi, Takaaki Tsurumi, Osamu Fukunage, and Junzo Tanaka, "Effect of Lanthanide Substitution on Superconductivity of La1.85-xRxCa1.15Cu2O6-d (R = Pr, Nd and Y)." To be published in Physica C (in press). Contact Naoki Ohasi, Department of Inorganic Materials, Faculty of Engineering, Tokyo Instiute of Technology, 2-12-1 O-okayama, Meguro, Tokyo 152, JAPAN; e-mail nohashi@tssun.ceram.titech.ac.jp. Key words: La2SrCu2O6-type, superconductivity, Rietveld analysis, occupation factor.
Shinjiro Tochihara, Hiroshi Yasuoka, and Hiromasa Mazaki, "Magnetization of Type-II Superconductors in the Modified Bean Model." To be published in Physica C (in press). Department of Mathematics and Physics, National Defense Academy, Yokosuka 239, JAPAN.
Ayako Tokiwa-Yamamoto, Tadashi Tatsuki, Seiji Adachi, and Keiichi Tanabe, "Superconductivity of (Hg0.7Tl0.3)2Ba2Y1-xCaxCu2O8-d (0<=x<=0.8) with a Wide Range of Doping State." To be published in Physica C (in press). Superconductivity Research Laboratory, International Superconductivity Technology Center (ISTEC), 10-13 Shinonome 1-chome, Koto-ku, Tokyo 135, JAPAN; telefax +81 3 3536 5714.
J. M. Tranquada, J. D. Axe, N. Ichikawa, A. R. Moodenbaugh, Y. Nakamura, and S. Uchida, "Coexistence of, and Competition Between Superconductivity and Charge-Stripe Order in La1.6-xNd0.4SrxCuO4." Brookhaven National Laboratory, Upton, NY 11973; telefax (516) 344-2918; e-mail jtran@bnl.gov; preprint also available at cond-mat@xxx.lanl.gov (#960848). 74.72.Dn; 71.45.Lr; 75.50.Ee; 75.70.Kw.
R. Usami, M. Itoh, A. Fukuoka, X.-J. Wu, and K. Tanabe, "Microstructure of Proton-Irradiated HgBa2Ca(n-1)CunOy (n=2,3)." Advanced Technology R & D Center, Mitsubishi Electric Corporation, 1-1-57 Miyashimo, Sagamihara, Kanagawa 229, JAPAN.
C. J. van der Beek, M. V. Indenbom, V. Berseth, M. Konczykowski, T. W. Li, P. H. Kes, and W. Benoit, "Influence of Columnar Defects on the Thermodynamic Properties of BSCCO." Presented at the XXI Int. Conf. on Low Temperature Phys. (TL21), Prague, Czech Republic, Aug. 8-14, 1996; to be published in Czech. J. Phys. I.G.A., Department de Physique, Ecole Polytechnique Federale de Lausanne, CH-1015 Lausanne, SWITZERLAND; e-mail kees@igahpse.epfl.ch.
C. J. van der Beek, M. V. Indenbom, V. Berseth, T. W. Li, and W. Benoit, "Onset of Bulk Pinning in BSCCO Single Crystals." To be published in J. Low Temp. Phys.: Proc. of the Int. Conf. on Phys. and Chem. of Molecular and Oxide Supercond. (MOS'96), Karlsruhe, Germany, Aug. 2-6, 1996. I.G.A., Department de Physique, Ecole Polytechnique Federale de Lausanne, CH-1015 Lausanne, SWITZERLAND; e-mail kees@igahpse.epfl.ch.
Karen Verbist, Anders Kuehle, Alexander L. Vasiliev, "Microstructural Comparison of YBa2Cu3O7-x Thin Films Laser Deposited in O2 and O2 /Ar Ambient." To be published in Physica C. EMAT, University of Antwerp (RUCA), Groenenborgerlaan 171, B-2020 Antwerp, BELGIUM. Key words: high-Tc superconductors, thin films, laser deposition, outgrowths, HREM.
Yong Wang and A. H. MacDonald, "Mixed-State Penetration Depths in s-Wave and d-Wave Superconductors." Preprint #IUCM96-020; submitted to Phys. Rev. Lett. Department of Physics, Indiana University, Bloomington, IN 47405. 74.60.Ec; 74.72.-h.
C. B. Whan and T. P. Orlando, "Transport Properties of a Quantum Dot with Superconducting Leads." To be published in Phys. Rev. B. Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA 02139. 73.40.Gk; 73.20.Dx; 73.50.Pz; 75.40.Mg.
D. G. Xenikos, H. Mueller, and P. Strobel, "Redox Intercalation of Iodine into Bi2Sr2Can-1CunOx (n = 2, 3)." To be published in Physica C (in press). Centre de Recherches sur Tres Basses Temperatures (CRTBT), CNRS, BP 166, F-38042 Genoble Cedex 9, FRANCE.
Lu Zhang, J. Z. Liu, C. Hoellwarth, S. H. Irons, R. N. Shelton, and M. D. Lan, "Hysteresis Loop, Irreversibility Line and Flux Creep Studies in TlBa2Ca3Cu4O11-d Single Crystals." To be published in Physica C (in press). Department of Physics, California State University, Stanislaus, Turlock, CA 95382; telefax (209) 667-3099; e-mail zhang@toto.csustan.edu.
Michael Ziese, "Vortex Motion in Inhomogeneous Superconductors: Linear Response." To be published in Physica C. Department of Superconductivity and Magnetism, University of Leipzig, Linnestrasse 5, D-04013 Leipzig, GERMANY; e-mail ziese@physik.uni-leipzig.de. Key words: flux creep, flux pinning, magnetoresistance, percolation. 74.60.Ge; 74.72.-h; 64.60.Ht.
*Sept. 17 - 20, 1996: International Symposium on Advances in Superconductivity: New Materials, Critical Currents, and Devices; Tata Institute of Fundamental Research, Bombay, India. Part of the Golden Jubilee celebration of TIFR. Main objective is to provide a forum to review the progress in the experimental and theoretical studies of the new superconductors. Emphasis on recent developments in areas of new materials and device applications. Plenary lectures, invited talks, panel discussions, and contributed and poster sessions. Topics will include new compounds and novel synthesis methods; vortex structure, pinning, and dynamics; active and passive devices; recent developments in high-Tc theories; thin films and artificial structures; critical currents; and novel applications. For further information, contact R. Pinto or P. Ayyub, Materials Research Group, Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Bombay 400 005, India; telephone +91 22 215 2971, ext. 2446; telefax +91 22 215 2110; e-mail asmccd@tifrvax.tifr.res.in or pushan@tifrvax.tifr.res.in.
*Nov. 12 - 15, 1996: 41st Annual Conference on Magnetism & Magnetic Materials, Atlanta Hilton Towers, Atlanta, GA. Sponsored jointly by the American Institute of Physics and the Magnetics Society of the IEEE. Conference will include all areas of basic and applied science and technology related to magnetism. Technical subject categories will include fundamental properties and cooperative phenomena, transport properties, computational magnetics and imaging, soft magnetic materials and applications, hard magnetic materials and applications, artificially structured materials, other magnetic materials, magnetic recording, applications, and interdisciplinary topics. Proceedings to be published in a special issue of J. Appl. Phys. Invited and contributed papers as well as an exhibition of services, equipment, and materials. For further information, contact Diane Suiters, Conference Coordinator, 655-15th St. N.W., Suite 300, Washington, DC 20005; telephone (202) 6395088; telefax (202) 347-6109; e-mail magnetism@mcimail.com. (Preliminary program and general conference information available after Sept. 15, 1996, at the URL address http://www.aip.org/edops/mmm96prog.html.)
*Dec. 2 - 6, 1996: MRS Fall Meeting: Symposium GG -- High-Temperature Superconductivity - Interplay of Fundamentals and Applications. This symposium will focus on two general problems of interest to both fundamental research and commercial applications: (1) critical currents in bulk high-temperature superconductor materials, and (2) superconductor interfaces in thin-film materials. Goal is also to foster interactions between researchers concerned with problems from both perspectives. Experimental and theoretical papers in the following topics to be presented: vortex structure, pinning, and dynamics; critical currents; wire and tape processing and properties; thin-film growth; heterostructures and interfaces; devices; and applications. Contact one of the symposium organizers: Charles M. Lieber, Department of Chemistry, Harvard University, 12 Oxford Street, Cambridge, MA 02138; telephone (617) 496-3169; telefax (617) 496-5442 or -6731; e-mail cml@cmliris.harvard.edu; or Ivan Bozovic, MS K-114, Edward Ginzton Research Center, Varian Associates, Inc., 3075 Hansen Way, Palo Alto, CA 94304-1025; telephone (415) 424-6358; telefax (415) 424-6988; e-mail ivan.bozovic@grc.varian.com. Information also available at the MRS homepage http://www.mrs.org.
*Dec. 16 - 21, 1996: International Workshop on High-Temperature Superconductivity: Ten Years After Its Discovery, Jaipur, India. Organized by Drexel University, Philadelphia, and University of Rajasthan, Jaipur, and sponsored by the U.S. National Science Foundation. The primary purpose is to bring researchers from India and other countries together to discuss latest developments, to promote dialogue among different groups, and to encourage cooperative activities and international collaborations. The second objective is promotion of science and engineering education focused on the needs of young researchers in the field. Lectures and discussions to be presented by prominent scientists from the U.S. and other countries. Space limitation may restrict number of participants. For further information, contact Workshop Chairs: S. M. Bose, Department of Physics and Atmospheric Science, Drexel University, Philadelphia, PA 19104; telephone (215) 895-1706; telefax (215) 895-4999; e-mail bose@duvm.ocs.drexel.edu; or K. B. Garg, Department of Physics, University of Rajasthan, Jaipur, India; telephone and telefax +91 141 511912; e-mail cmpl@sirnetd.ernet.in.
*Feb. 23 - 25, 1997: 1997 International Symposium on Intrinsic Josephson Effect and THz Plasma Oscillations in High Tc Superconductors, Institute of Materials Research, Tohoku University, Sendai, Japan. Topics will include cuprate superconductors, single crystals, highquality thin films, anisotropic electronic and magnetic properties, vortex flow in layered structures, high-frequency plasma oscillations, far-infrared properties, and high-frequency electronic devices. Invited, oral, and poster contributions. Preregistration deadline, October 15, 1996; abstract deadline, November 15, 1996. Official language is English. Proceedings to be published in Physica C. For further information, contact Kensuke Makajima or Sergei E. Shafranjuk, Research Institute of Electrical Communication, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980, Japan; telephone +81 22 217-5472 or -5476; telefax +81 22 217-5473; e-mail knaka@riec.tohoku.ac.jp or sergei@riec.tohoku.ac.jp.
*Feb. 28 - March 4, 1997: Fifth International Conference on Materials and Mechanisms of Superconductivity and High-Temperature Superconductors (M2S-HTSC-V), Beijing, China. Topics include high-Tc materials; physical properties of high-Tc materials; magnetism and superconductivity; vortices, pinning, and flux melting; thin films and multilayers; Josephson junctions; applications; heavy fermions; organic superconductors; fullerenes; and theory. Exhibition of high-Tc superconducting materials, low-temperature experimental appliances, and cryogenic engineering and refrigeration instruments. Conference language is English. Abstract deadline, September 1, 1996. For information, contact D. Jin, M2S-HTSC-V Secretariat, Cryogenic Laboratory, Chinese Academy of Sciences, P.O. Box 2711, Beijing 100 080, People's Republic of China; telephone +86 10 255 1143; telefax +86 10 256 4049; e-mail djin@cl.cryo.ac.cn. Information also available at the Web page http://sun1.bham.ac.uk/hey/conferences/M2S-HTSC-V.htm.
*March 6 - 8, 1997: International Workshop on Crystal Chemistry of High-Tc Superconductors (CC-HTSC'97), Hefei, China. Satellite conference to the Fifth International Conference on Materials and Mechanisms of Superconductivity (M2S-HTSC-V) at Beijing. Crystal chemistry, structure, as well as other related topics on high-Tc superconductors. (Submitted papers should not have been presented at the M2S-HTSC-V Conf. in Beijing). Main topics are new superconductors and their crystal structures, microstructures and modulated structures, crystal growth and structure determination, electronic structures, chemical bonding in superconductors, phase diagram, crystal structure of fullerenes, intermetallic-compound superconductors, and other related materials. Conference language is English. Further details to be announced in second circular. For information, contact LI Xiao-Guang, CC-HTSC'97 Conference Secretary, Structure Research Laboratory, University of Science and Technology of China, Hefei, China; e-mail lixg@email.sc.ustc.ac.cn.
May 25 - 29, 1997: 9th International Symposium on Intercalation Compounds (ISIC 9), Bordeaux-Arcachon, France. Will focus on basic concepts in the chemistry and physics of intercalation compounds. Contributions solicited in the following topics: new intercalation compounds and synthesis routes; thermodynamics, kinetics, and reaction mechanisms; structure and lattice dynamics; phase transitions; electronic properties, charge transfer, and band-structure calculations; transport properties; superconductivity; magnetic properties; electrochemical properties; intercalation electrodes for advanced batteries; and other present and potential applications. For further information, contact ISIC 9, Centre de Recherche Paul Pascal, Avenue Albert Schweitzer, F-33600 Pessac, France; telephone +33 5684 5632; telefax +33 5684 5600; e-mail mondolfi@crpp.u-bordeaux.fr.
Aug. 25 - 28, 1997: 16th General Conference of the Condensed Matter Division of the European Physical Society, Katholieke Universiteit Leuven, Leuven, Belgium. Particular emphasis on the following areas: low-temperature physics and superconductors, magnetism and metals, semiconductors and insulators, soft matter and statistical mechanics, and surfaces and interfaces. Special symposium "Forty Years of the Vortex State" by A. A. Abrikosov. For further information, contact The Secretary-General, 16th CMD-General Conference, Departement Natuurkunde K. U. Leuven, Celestijnenlaan 200 D, B-3001 Leuven, Belgium; telephone +32 16 32 71 75; telefax +32 16 32 79 83.
Sept. 7 - 20, 1997: Summer School on Superconductivity in Networks and Mesoscopic Structures, Certosa di Pontignano, Siena, Italy. Aimed at Ph.D. students and postdoctoral researchers. School will provide opportunity for interaction with experts from different fields and include topics such as simulation of complex dynamic systems, quantum and classical theories, Monte Carlo simulations, and others. Application deadline, Oct. 31, 1996. Contact C. Giovannella, Dipartimento di Fisica, Universita di Roma "Tor Vergata", Via della Ricerca Scientifica 1, I-00133 Rome, Italy; telephone +39 6 7259 4524; telefax +39 6 202 3507; e-mail supnet@roma2.infn.it. Information also available at the web site http://wwwas.roma2.infn.it/.
Information
New Book: Recent Advances in the Chemistry and Physics of Fullerenes and Related Materials: Volume 3, edited by R.S. Ruoff and K. M. Kadish. This approx. 1300-page hardbound book is third in the series. Contains contributions from numerous researchers in the field and is sponsored by the Fullerenes Group of the Electrochemical Society. Book is organized according to the following topics: technology and polymers, photoexcited states, extraction and purification, ESR, theory, electrochemistry, gas phase and mass spectroscopy, organometallic chemistry, solid-state properties, metallofullerenes, thermodynamics and thin films, biochemistry and pharmaceutical chemistry, carbon-coated nanocapsules and nanotubes, organic functionalization, and fullerenebased superconductors. Price $82 (members), $98 (non-members). For additional information, contact The Electrochemical Society, Inc., 10 South Main Street, Pennington, NJ 08534-2896; telephone (609) 737-1902; telefax (609) 737-2743; e-mail ecs@electrochem.org or http://www.electrochem.org.
New Book: Handbook of Microscopy -- Applications in Materials Science, Solid-State Physics and Chemistry, edited by S. Amelinckx, D. Van Dyck, J. Landuyt, and G. Van Tendeloo.
Volume 1, Methods: Intended as a hands-on reference source for the experimentalist. Includes the physico-chemical background of individual techniques, instrumentation, and image analysis. Covers light, x-ray, and acoustic microscopy; microtomography; scanning laser acoustic microscopy; electron microscopy; scanning-beam methods; magnetic methods; microscopy with polarization analysis (SEMPA); emission methods; field-emission-microscopy (FEM) techniques; image recording; and handling and processing. Publ. 1996; 600 pp.; ISBN 3-527-29280-2.
Volume 2, Applications: Structured according to material type, this volume evaluates the different techniques available for characterizing a given material. Categories include metals and alloys, rocks and minerals, semiconductors and semiconducting devices, opto-electronic materials, ferrous materials, structural ceramics, gemological applications, superconductors (intermetallics and ceramics), nonperiodic structures, biomaterials, application of TEM and SAED, different forms of carbon, composite structural materials, polymers, nuclear materials, and magnetic materials. Special topics: phase transformations, specimen-preparation techniques, environmental problems, and thin-film growth. Publ. 1996; 500 pp.; price DM 450 (per volume) or DM 798 (per set); ISBN 3-527-29293-4. Contact VCH, P.O. Box 10 11 61, D-69451 Weinheim, Germany; telefax +49 6201 606-184.
The information contained herein is intended for limited distribution. Readers are expected to respect the rights of the authors.
Please address all contributions and inquiries to: Dr. Sreeparna Mitra, A219 Physics, Ames Laboratory/Iowa State University, Ames, Iowa 50011-3020. Telephone: (515) 294-3877. Telefax: (515) 294-1134. Telex: 269266. E-mail: MITRA@AMESLAB.GOV or MITRA@IASTATE.EDU.
Project Director/Editor: Sreeparna Mitra
Science Editor: John R. Clem
High-Tc Update, Vol. 10, #17, September 1, 1996.