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, NIST, and other agencies, organizations, and individuals.
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T_x
It is experimentally well established that the magnetization curves M(T,H) vs. T of Bi2Sr2CaCu2O8+d (Bi-2212) cross at a common temperature T*. A paper by O. Jeandupeux (ETH-Zurich) et al. now reports a similar, but different, phenomenon. Starting from sets of experimental magnetization data, the authors numerically determined the temperature derivatives of M(T,H) for both a large twinned single crystal of YBa2Cu3O7-d and a polycrystalline textured sample of Bi-2212. The authors found that the del-M(T,H)/del-T curves for different external magnetic fields H cross at distinct temperatures T_x = 92 K for YBa2Cu3O6.9 and T_x = 93.5 K for Bi-2212. The relevant Maxwell relation, mu_0 del-M/ del-T = del-S/ del-H, implies that the entropy S varies perfectly linearly with H at the temperatures T_x.
Vortex-Lattice Melting
A sharp paramagnetic peak in the local ac susceptibility chi' at the first-order vortex-lattice melting transition in Bi2Sr2CaCu2O8+d (Bi2212) crystals has been found by N. Morozov (Weizmann Institute) et al. The authors assert that the presence of this peak establishes the thermodynamic nature of the transition and allows accurate evaluation of the equilibrium magnetization step height. The associated estimated entropy change Delta-s reaches values in excess of 6 k_B per pancake vortex near Tc. The local chi" shows two independent loss peaks: a broad one caused by the onset of irreversible magnetization and a narrow one due to hysteresis at the phase transition.
An anomalous magnetization step, providing further thermodynamic evidence for a first-order vortex-lattice melting transition in YBa2Cu3O7-d single crystals is reported by T. Nishizaki et al. (Tohoku). The feature occurs at the same place in the H-T phase diagram as the resistive kink. For samples with a small value of the irreversibility field H_[irr](T), less than the melting field H_m(T), the melting transition occurs in the reversible magnetization region, and the entropy change per pancake vortex is estimated to be Delta-s ~~ 0.5-1.0 k_B. For samples with H_[irr](T) larger than H_m(T), the jump height and the value of Delta-s are enhanced.
A preprint by T. Naito (Tohoku) et al. reports magnetization evidence for the vortex-lattice melting transition in a La1.85Sr0.15CuO4 single crystal.
Longitudinal Effects
A scaling theory of vortex motion in Bose-glass superconductors with currents parallel to the common direction of the magnetic field and columnar defects has been developed by D. R. Nelson (Harvard) and L. Radzihovsky (Colorado). Above the Bose-glass transition, the longitudinal dc resistivity rho_||(T) proportional to (T-T_[BG])^[v'z'] is found to vanish much faster than the corresponding transverse resistivity rho_[perp.] proportional to (T-T_[BG])^[v'(z'-2)], thus reversing the usual anisotropy of electrical transport in the normal state of layered superconductors. In the presence of a current J at an angle theta_J with the common field and columnar defect axis, the electric field angle theta_E approaches pi/2 as T --> T_[BG]^+. Scaling also predicts the behavior of penetration depths for ac currents as T --> T_[BG]^-, and implies a jump discontinuity at T_[BG] in the superfluid density describing transport parallel to the columns.
Magneto-optical studies of YBa2Cu3O7-d single crystals carrying induced ac currents parallel to the applied magnetic field (force-free-current configuration) have been carried out by M. V. Indenbom (EPFL and Chernogolovka) et al. The authors found magnetic-flux instabilities that penetrate the sample as a very sharp front. In the case of repeated field reversals, current strings with helical magnetic structure and asynchronous flux waves were generated. Closely related work is reported by V. Berseth (EPFL) et al.
RBCO
Neutron-diffraction and inelastic neutron-scattering results on HoBa2Cu3O7 are presented in a preprint by U. Staub (ETH and PSI) and C. Ritter (ILL-Grenoble). The neutron-diffraction experiments reveal the onset of short-range order in the Ho^[3+] sublattice at 1.6 K, far above the hyperfine-induced ordering temperature T_N = 190 mK. A strong enhancement of the effective susceptibility compared with a Curie-Weiss susceptibility is found above 400 mK. This enhancement explains why short-range ordering of the Ho^[3+] spins with an in-plane correlation length of 13 Angstroms is detectable at these temperatures.
Using high-Q double-torsional silicon oscillators vibrating at extremely low amplitude, A. L. Barr and J. T. Markert (Texas-Austin) have observed numerous fine minima and maxima in the dissipation vs. temperature data for certain characteristic fields parallel to the layers in singlecrystal YBa2Cu3O7-d. These features are mirrored in the frequency shift vs. temperature data. To explain these features, the authors suggest an intrinsic-pinning model in which the dissipation minima correspond to conditions of commensurability between the interlayer spacing and both the coherence length and Abrikosov lattice spacing.
The longitudinal and Hall resistive transitions of YBa2Cu3O7-d films in applied fields up to 9 T have been measured by W. Liu (Maryland) et al. The longitudinal fluctuation conductivities obey the scaling behavior of the 3D Hartree fluctuation theory of Ullah and Dorsey. The fluctuation Hall conductivities do not scale. The authors were able to separate the Aslamazov-Larkin (AL) and the Maki-Thompson (MT) terms. The AL Hall conductivity follows a scaling law, and the AL and MT terms have opposite signs. The sign of the AL term is consistent with the sign change in the flux-flow regime, as predicted by theory. At low fields and temperatures just above Tc(H), the AL term dominates the MT term, thereby causing the total Hall conductivity sign change.
The effects of the surface structure and chemistry of YBa2Cu3O7-d on the low-temperature, low-field ac susceptibility chi' have been studied by C. Panagopoulos (IRC-Cambridge) et al. The authors found that grinding sintered material in air into particles of average radius 5 micrometers caused a small paramagnetic upturn below 12 K; a larger effect was observed for smaller particles. The authors found that these upturns could be removed by a suitable annealing treatment, after which a linear T dependence in chi' and consequently in the magnetic penetration depth lambda was then observed. High-resolution electron microscopy was used to monitor the changes in the surface structure of the particles.
A related paper by C. Panagopoulos (IRC-Cambridge) et al. reports ac susceptibility investigations of the temperature and doping dependencies of the anisotropic penetration depth lambda of high-quality grainaligned YBa2(Cu1-xZnx)3O7-d with x = 0.00, 0.02, 0.03, and 0.05. The values of the in-plane and out-of-plane penetration depths lambda_[ab](0) and lambda_c(0) were found to increase strongly with increased Zn concentration, but the anisotropy ratio gamma = lambda_c(0)/lambda_[ab](0) decreased. The authors also found that, with increased Zn doping, the [lambda_[ab](0)/lambda_[ab](T)]^2 and [lambda_[ab](0)/lambda_c(T)]^2 curves systematically approached each other.
The microstructure and superconducting properties of directionally solidified YBa2Cu3O7-d/Y2BaCuO5 composites have been investigated by N. Vilalta (Barcelona) et al. using transmission electron microscopy and ac and dc magnetic measurements. The authors found that plastic deformation of high-critical-current samples decreases the activation energy for flux motion and shifts the irreversibility line toward low fields and temperatures. This behavior is directly correlated with the observed microstructure, which is dominated by microcracks and large stacking faults, which in turn decrease the vortex correlation along the c axis.
A preprint by A. Erb et al. (Geneve) reports on the absence of the socalled fishtail or peak effect in the magnetization curves of properly oxygenated high-purity single crystals of YBa2Cu3O7-d. In this paper, the authors show how to reversibly produce or remove the fishtail effect by various oxygenation methods. The authors assert that these experiments prove that in high-purity samples the fishtail effect is due to different oxygenation states and/or oxygen distributions. In less pure samples, however, other sources, such as metallic impurities, can assist in producing the fishtail anomaly.
Bi Cuprates
Measurements of the reversible mixed-state magnetization of Bi2.08Sr1.92CuO6+d (Bi-2201) have been carried out by E. Janod et al. (CEA-Grenoble) and used to compare with theoretical predictions for different symmetries of the order parameter. The authors find that Bi2201 follows neither the behavior expected for s-wave pairing nor that for pure d-wave pairing. However, an approach involving a d-wave model with lines of nodes on the Fermi surface in the presence of impurities provides a good description of the measurements and yields realistic estimates of the free parameters. The authors also show that the rapid decrease in amplitude of the specific-heat anomaly at Tc of 2D hightemperature superconductors in magnetic field is explainable in terms of the unconventional pairing symmetry.
A preprint by L. Winkeler et al. (Aachen) reports that Pb substitution for Bi in single crystals of highly anisotropic Bi2Sr2CaCu2O8+d (Bi2212) produces a decrease of the structural anisotropy. As a result, the out-of-plane resistivity rho_c(T) is reduced by four orders of magnitude, and the temperature dependence changes from semiconductorlike (drho_c/dT < 0) to metallic (drho_c/dT > 0). The authors explain the results by assuming that Pb doping introduces an additional covalent type of bonding between the BiO bilayers, which is not present in the undoped crystals.
An extensive study of the formation process of (Bi,Pb)-2223 starting from different precursors has been carried out by A. Jeremie and R. Fluekiger (Geneve). The authors have established that the (Bi,Pb)-2223 formation is the same regardless of the precursor powder type studied. In addition, the authors confirmed their previous mechanism by which Bi2212 converts to (Bi,Pb)-2223 by the intermediate formation of Pbcontaining (Bi,Pb)-2212.
A preprint by M. Chung (Clemson) et al. reports the characterization of Bi-based cuprate superconducting whiskers. The whiskers were typically 2-10 mm long, 10-100 micrometers wide, and 1-5 micrometers thick, and were found to contain a mixture of the Bi-2212 and Bi-2223 phases.
Tl Cuprates
High-resolution O K-edge and Cu L_[23]-edge x-ray-absorption near-edgestructure (XANES) spectra of a single-phase high-Tc Tl2Ba2Ca2Cu3O10 (Tl2223) superconductor in powder form were measured by J. M. Chen (SRRCHsinchu) et al. using the total-electron-yield (TEY) and total-x-rayfluorescence yield (TFY) techniques. Near the O 1s edge, three distinct pre-edge peaks with maxima at 528.3, 529.6, and 530.8 eV were revealed in the TFY spectrum but were suppressed in the TEY spectrum. The observed differences between the TFY and TEY spectra can be explained by the presence of an oxygen depletion layer.
An efficient and highly reproducible method for the preparation of single-phase Tl-2223 and (Tl,Pb)-1223 materials by fine-tuning the chemical compositions of Tl2-xBa2Ca2+xCu3O10-d (Tl-2223) and (Tl0.5Pb0.5)Sr2-xCa2+xCu3O9-d [(Tl,Pb)-1223)] is reported by R. S. Liu (National Taiwan). The author reports how to optimize Tc by using an appropriate post-annealing process.
A preprint by R. P. Vasquez (JPL) et al. reports measurements of the valence electronic structure and core levels of Tl2Ba2CuO6+d (Tl-2201) epitaxial films by x-ray photoelectron spectroscopy, and comparisons with the properties of Tl2Ba2CaCu2O8+d (Tl-2212). Changes in the Tl2201 core-level binding energies with oxygen doping are consistent with a change in the chemical potential. Differences between the Tl-2201 and Tl-2212 measured densities of states are consistent with the calculated Cu 3d and Tl 6s partial densities of states.
Other Cuprates
Anomalously large and highly reproducible cusps in the temperaturedependent surface-resistance data have been observed by F. J. Owens (AAR and Hunter College) et al. using contactless microwave loss measurements at 9.2 GHz in (Sr,Ca)14Cu24O41, a novel cuprate with quasi-onedimensional two-legged-ladder Cu2O3 planes and edge-sharing CuO2 chains. The onset temperatures of the microwave cusps, which were as high as 270 K, decreased with increasing calcium content and nitrogen annealing. No indications of bulk superconductivity were evident in dc magnetic susceptibility and ac resistance measurements in the 80 to 300 K and 15 to 300 K temperature ranges, respectively. However, a rapid increase in intensity of the Cu2+ electron paramagnetic resonance signal, which the authors attribute to persistent currents in filamentary fractions of the samples, occurred at temperatures near the minima of the cusps. The authors tentatively interpret the observed cusps in the microwave data as superconductive pairing fluctuations close to a charge-density-wave instability in the quasi-one-dimensionally structured ladder planes in optimally doped intergranular interfaces of the ceramic specimens.
Measurements by N. Momono and M. Ido (Hokkaido) have shown that the electronic specific heat C_[el] of La2-xSrxCuO4 (0.16 <= x <= 0.22) exhibits a T^2 dependence at T << Tc, consistent with clean d-wave superconductivity. Substitution of as little as 0.3-0.5% Zn for Cu, however, changes the T^2 dependence of C_[el] to the sum of T and T^3 terms, which agrees with theoretical results for a d-wave superconductor with impurity scattering centers in the unitarity limit.
Single crystals of Hg0.8Bi0.2Ba2CuO4+d [(Hg,Bi)-1201] have been grown and studied by D. Pelloquin et al. (Caen). The crystals exhibit superconductivity up to 75 K, with Tc(midpoint) = 62 K.
A paper by A. Brazdeikis (Royal Institute of Technology, Stockholm) et al. shows that a small amount of doping of Tl2O3 in the bulk material significantly promotes the formation of superconducting Hg-Ba-Ca-Cu-O films during encapsulated post-annealing. The authors also have used this method to prepare good-quality superconducting HgBa2CaCu2O6+d films using Hg-free thin-film precursors. The as-prepared films are strongly c-axis-oriented and exhibit zero-resistance Tc as high as 117 K.
Thin Films
As reported by A. Beck (Tuebingen) et al., La1.85Sr0.15CuO4-d grainboundary Josephson junctions have been fabricated on [001] tilt SrTiO3 bicrystals with misorientation angles of 24 degrees and 36.8 degrees. The resistive transitions and current-voltage characteristics were found to be close to those predicted by the resistively shunted junction (RSJ) model.
The fabrication of different kinds of Josephson junctions based on Bi2212 and Tl-2212 thin films is described in a paper by A. Pfuch et al. (Jena). The authors first discuss biepitaxial and bicrystalline Bi-2212 Josephson junctions. They then discuss the preparation and properties of intrinsically stacked Josephson junctions in Tl-2212 and Bi-2212, in which the current-voltage characteristics for current transport along the c direction are those appropriate for many Josephson junctions connected in series.
The ab-plane ac resistivity (3 mHz - 50 MHz) of c-axis-oriented YBa2Cu3O7-d and Bi2Sr2CaCu2O8+d (Bi-2212) films has been studied by G. Nakielski (Hamburg) et al. before and after irradiation by 2.7 GeV [238]^U ions (H_[phi] = 10 kOe) to produce columnar defects parallel to the c direction. In YBa2Cu3O7-d, an increase in the glass transition temperature T_g(H) was observed both upon irradiation (for H <= H_[phi]) and upon changing the field direction from H||c to H perp. to c. Surprisingly, in highly anisotropic Bi-2212, the columnar defects parallel to c raise T_g(H) even for H perp. to c.
The microstructure of a Tl2Ba2CaCu2O8+d (Tl-2212) superconducting thin film grown by metal-organic chemical vapor deposition (MOCVD) on a pseudo-cubic (001) LaAlO3 substrate has been examined by X. F. Zhang (Argonne) et al. using analytical transmission microscopy (TEM) and high-resolution electron microscopy (HREM). The film was found to be epitaxial over large regions, and the Tl-2212 phase was found to be the major phase. The film/substrate interface was found to be abrupt and smooth on the atomic scale, but a strain field was found to be induced by the lattice mismatch between the film and the substrate.
Applications
The development of high-Tc SQUIDs based on Josephson step-edge junctions on silicon substrates is discussed in a paper by P. Seidel et al. (Jena). The authors have investigated the growth of YBCO, buffer, and passivation layers as well as step-preparation and patterning processes to find a standard preparation process comparable with that for Josephson step-edge junctions on classical substrates.
The physics and performance of high-temperature-superconducting (HTS) Josephson vortex-flow transistors (JVFTs) are discussed by R. Gross (Koeln) et al. In these devices, the flow of Josephson vortices is controlled by the magnetic field of a gate current. The authors report that in HTS-JVFTs based on YBCO grain-boundary Josephson junctions, transresistance values of several ohms have been achieved. For asymmetric devices, a current gain above 30 has been obtained below 60 K, making these devices promising for applications.
A preprint by Yu. P. Gousev et al. (Regensburg) reports on efficient coupling of THz radiation to a high-Tc hot-electron bolometer that is suitable for heterodyne detection. The authors' quasioptical system consisted of a planar self-complementary spiral antenna on a dielectric substrate clamped to an extended hyperhemispherical lens. The antenna was integrated into a coplanar line for broadband intermediate frequency matching.
A study of the thermal stability of (Bi,Pb)-2223/Ag pancake coils at 77 K is reported by N. V. Vo (Wollongong) et al. The authors find that the stability is controlled by the amount of matrix and superconducting materials during processing. They also report that the intermediate deformation step between sintering stages is crucial in optimizing the performance of the processed composite tapes and in governing the thermal stability of the pancake coils.
Theory
A new kind of superconductivity is predicted in a paper by W. E. Pickett (NRL). The author proposes that a spin-compensated half-metallic ferromagnet (HMFM) provides the possibility of achieving a new, axial type of superconductivity in which only one spin channel is superconducting. This triplet-superconductivity S = 1, M_S = 1 pairing state, which arises from a unique kind of normal state, is predicted to differ markedly from conventional, heavy-fermion, or high-temperature superconductors. The author outlines the characteristics of such a state and offers guidelines for making compounds where it might be found.
The vertex corrections of the dynamical spin susceptibility have been calculated by T. Dahm and L. Tewordt (Hamburg) for a Hubbard model with intermediate coupling strength (U/t = 7) and a Fermi surface approximating that of YBa2Cu3O7. Below Tc, the resulting q dispersion of the coupling J(q) yields for d_[x^2-y^2] pairing a resonant-like peak in the spectral neutron scattering weight in qualitative agreement with experiments on YBa2Cu3O6+x.
The one-dimensional t-J Holstein model has been studied by R. Fehrenbacher (Argonne) by exact diagonalization of finite rings using a variational approximation for the phonon states. Because of renormalization effects induced by the phonons, for intermediate electron-phonon coupling both the phase separation boundary and the region of dominating superconducting fluctuations are shifted substantially to smaller values of J/t relative to the results in the pure t-J model. Superconducting correlations are weakened through charge-density-wave interactions mediated by the phonons.
Various aspects of the normal-state phase of CuO2 planes in the high-Tc superconductors have been examined by B. C. den Hertog and M. P. Das (Australian National). Using the three-band Hubbard model, the authors studied the doping dependence of the competition of a charge-densitywave phase induced by oxygen breathing modes, antiferromagnetic order, and paramagnetism. To account for the strong electronic interactions, the authors used the finite-U slave-boson method of Kotliar and Ruckenstein.
Results for a model calculation of resonant two-magnon Raman scattering in a spin-density-wave antiferromagnet are presented in a preprint by F. Schoenfeld et al. (Koeln). The resonant enhancement of the two-magnon intensity is obtained from a microscopic analysis of the photon-magnon coupling vertex.
The effect of Josephson coupling between adjacent superconducting layers upon the BCS energy spectrum has been studied by A. Gauzzi and J. Bok (Paris). The authors find that interference between the gap functions of two layers can lead to vanishing energy gap at certain values of the perpendicular momentum k_z. The authors predict that compounds with large spacing between adjacent CuO2 layers, such as the systems with one layer per unit cell (La2-xSrxCuO4, Nd2-xCexCuO4, Tl-1201, Tl-2201, and Bi-2201), will always exhibit conventional BCS behavior if the gap of the single layer has no nodes. On the other hand, all the systems with two or more adjacent CuO2 layers per unit cell, such as YBa2Cu3O7-d, Bi2212, and Bi-2223, are expected to exhibit gapless behavior. The authors' numerical results account within experimental error for the exponential and linear low-temperature dependencies of the penetration depths reported in Nd1.85Ce0.15CuO4 and YBa2Cu3O6.9, respectively.
A preprint by M. T. Beal-Monod (Orsay) and K. Maki (USC) generalizes their d + s model to take into account the normal-state anisotropy. The anisotropy affects not only the ab anisotropy in the transport coefficients but also the density of states and other thermodynamic quantities in the superconducting state.
A self-consistent nonlocal approach for the description of vortices parallel to the layers in layered superconductors containing planar defects is presented by A. Gurevich (Wisconsin) et al. The model takes into account interlayer Josephson coupling and the reduced maximum Josephson current density J_0' across the defect as compared with the J_0 for the other interlayer junctions. The authors give analytical formulae that describe the structure of both static and moving vortices, including the nonlinear Josephson core region.
The relation between random telegraph noise and 1/f voltage fluctuations in current-biased high-Tc films has been investigated theoretically and experimentally by G. Jung (Ben Gurion, Beer-Sheva and Warsaw) and B. Savo (Salerno). The experiments have revealed that the telegraph noise in high-Tc superconducting films is due to a combined action of a macroscopic two-level fluctuator and a detector.
The electronic contribution kappa_e to the thermal conductivity of a two-dimensional superconductor with saddle points at the Fermi level in the band structure, corresponding to logarithmic van Hove singularities in the density of states, has been calculated by M. Houssa and M. Ausloos (Liege) using a variational method. The authors compare the theoretical results obtained for both isotropic s-wave and anisotropic d_[x^2-y^2]-wave gap parameters. Although the peak structure observed just below Tc in the thermal conductivity of a Bi-2212 single crystal can be reproduced by both gap-parameter symmetries, the low-temperature behavior of kappa can be explained only by a d-wave gap parameter.
Other Activities
A preprint by J. Diederichs et al. (Washington University) reports that the functional dependence of Tc on the electronic density of states N(E_F) in Rb3C60 has been determined by magnetic susceptibility measurements under hydrostatic pressure to ~1 GPa in a commercial SQUID magnetometer. Both Tc and N(E_F) decrease under pressure at the rates -31%/GPa and -14.5%/GPa, respectively, but lie above the corresponding values for K3C60 at the same lattice parameter. The results are consistent with weak-coupling BCS theory with characteristic energy E_[char]/k_B in the range 320-810 K.
The dynamic epidemic model has been investigated by N. Vandewalle and M. Ausloos (Liege) for the evolution of an advancing interface through a medium containing mobile impurities. The approach should apply to melttexturing of YBa2Cu3O7-d and related materials.
Ultrasonic-velocity measurements of a series of rare-earth-based and Bibased cuprate superconductors have been carried out by R. R. Reddy and P. V. Reddy (Osmania) using a pulse transmission technique over a temperature range of 80-300 K. The elastic moduli predicted by three different models (Watchman, Varshni, and Lakkad) all agree with experiment in the temperature region 150-300 K, where there are no elastic anomalies. Anomalies occur in the temperature range 80-150 K, where the theory fails. The Young's moduli were measured and found to vary as T^4 at low temperatures and as T at high temperatures.
Overviews
Experimental studies of magnetic relaxation in high-temperature superconductors are discussed in a review by Y. Yeshurun (Bar-Ilan) et al. The authors assess the results from an experimental perspective and examine them in the context of present phenomenological theories. The authors also summarize the implications for potential applications of the high-temperature superconductors (293 refs.).
The use of thermoanalytical methods to study oxygen stoichiometries in the high-Tc superconducting cuprates has been reviewed by M. Karppinen (Tokyo Institute of Technology and Helsinki University of Technology) et al. Included in the paper are discussions of studies of oxygen stoichiometries during annealing, the determination of absolute oxygen content by thermogravimetric methods, vapor-pressure studies, oxygenisotope studies, and confirmation of the oxygen stability of YBa2Cu4O8-y (78 refs.).
A review chapter describing research at CISE-Milan toward achieving high critical current densities in silver-sheathed Bi-2223 (Bi2Sr2Ca2Cu3O10+d) tapes prepared by the powder-in-tube (PIT) method has been prepared by L. Martini. The article covers sample preparation; tape layout; tape characterization; dependence of Jc on process parameters, tape geometry, axial strain, magnetic field, and temperature; evaluation of Jc from magnetization measurements; the irreversibility field; flux-pinning mechanisms; and current sharing (36 refs.).
Work done at UCSD on persistent photoconductivity and photoinduced superconductivity in RBa2Cu3Ox thin films has been reviewed by A. Hoffmann (UCSD) et al. The resistivity, Hall coefficient, and c-axis lattice parameter all change significantly upon illumination. These effects require the presence of oxygen vacancies, and the maximum enhancement of the conductivity upon illumination occurs for fully deoxygenated samples (x = 6.0). All the observations can be understood qualitatively with a model based on the trapping of photoexcited electrons at oxygen vacancies in the CuO chains (31 refs.).
Contributed by John R. Clem
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This section describes progress in manufacturing, product development, and technology transfer in the high-Tc superconductivity field. Please send your contributions (product development information, news regarding technology transfer efforts, or any information you would like to share about your corporation or laboratory) to the editor.
Researchers at the U.S. Department of Energy's Argonne National Laboratory and the University of Pittsburgh have developed a new silverwire-in-tube manufacturing technique that consistently produces superconducting wires with critical currents greater than 100,000 A/cm^2, considered the breakthrough value needed for practical applications. The new technique is based on a key refinement to the powder-in-tube (PIT) method for making HTS wire, which seals the superconducting powder inside a silver tube, then draws and rolls it into a wire resulting in a silver-clad ribbon of HTS material. Past research has found that the supercurrent in powder-in-tube wires flowed almost exclusively through a thin interface at the layer of superconductor closest to the silver casing, because of the right grain structure and alignment. In this project, researchers inserted a silver wire into the silver tube and filled the space in between with highquality Bi-2223 powder. After the wire was drawn and rolled, virtually all the BSCCO lay along the silver-superconductor interface and the resulting 1-2 micrometer-thick layer of superconductor consistently provided current densities of 100,000 A/cm^2. Before the silver-wirein-tube method, the best PIT wires could consistently carry only 20,00030,000 A/cm^2. The technology shows great promise for applications like electric motors, generators, transmission cables, and energy storage devices. The inventors see no barrier to making long lengths with the same improved performance. For more information, contact Dave Baurac, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439; (708) 252-5584 or dave_baurac@qmgate.anl.gov.
Department of Energy officials visited Southwire Company recently to discuss their joint superconductor wire project that began in October 1995. Southwire has designed and fabricated several samples of superconducting wire that have undergone extensive testing at Oak Ridge National Labs (ORNL) and a 1-m cable capable of carrying 500 A was displayed at the meeting. After testing in summer, Southwire plans to have a final 2,000 A cable ready by fall 1996. The company is also working with ORNL to design and build test equipment and perform electron-microscopy studies to characterize materials used in the project. For information, contact Kirsten Amley or Joel Reuter, Corporate Communications, Southwire Company, One Southwire Drive, Carrollton, GA 30119-4242; telephone (770) 832-4834 or -4466; telefax (770) 832-4929; e-mail kirsten_amley@southwire.com or joel_reuter@southwire.com.
Two additional rural field tests of its ultra-low-noise receiver subsystem for cellular base stations was carried out by Conductus, Inc. The subsystem is designed to provide enhanced range, improved coverage, and improved signal quality in rural cellular sites by combining a superconductive bandpass filter with a cryogenic low-noise amplifier. Tests were conducted at a Cellcom site in Wisconsin and in a Kansas Cellular site in Kansas. In both cases, the front-end receiver subsystem provided range and coverage improvements. Coverage problems in base stations, such as dropped calls, poor audio quality, and poor reception in hilly terrain are symptomatic of limited uplink sensitivity. Rural operators, in particular, are requiring improved cell-site coverage and extended range from their networks as consumers increase their demand for high-quality service from lower-power (0.6 W) portable phones (compared to 3-W mobile phones). In the Cellcom site test outside Green Bay, Wisconsin, the superconductive receiver increased the sensitivity of the base station's uplink by a factor of two, or 3 dB. Driving tests in the surrounding area verified that the base station's range increased by 21 percent from 14 miles to 17 miles in a situation where station line-of-sight range was limited by heavy terrain. In the Kansas Cellular field test, the Conductus front-end was installed at a cell site with an existing very-low-noise receiver that maximized uplink sensitivity by using only minimal filtering in the receiver. In this test, the system was able to increase the measured range of the station 16 percent, from 25 miles to 29 miles, while providing better filtering characteristics. These recent tests are part of a continuing program that has included earlier successful tests with GTE, formerly Contel Cellular, in Fresno, California last February, and with Peninsula Wireless Communications last November.
In a late-breaking news release, Conductus Inc., announced that it has completed a deployment agreement with Cellcom; per the agreement, Cellcom will install three ultra-low-noise receiver subsystems in their Wisconsin network this fall and will purchase the systems for permanent installation if they meet specific performance criterion. For further information, contact Stephen M. Garrison, Product Marketing Manager, Conductus, Inc., 969 West Maude Ave., Sunnyvale, CA 94086; telephone (408) 523-9430; telefax (408) 523-9999. Information also available at the URL http://www.best.com/~cdts/.
Contributed by Sreeparna Mitra
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A. L. Barr and J. T. Markert, "Fine Structure in a High-Resolution Vortex Dissipation Study of YBa2Cu3O7-d." To be published in Phys. Rev. Lett. Department of Physics, University of Texas at Austin, Austin, Texas 78712. 74.60.Ge; 74.72.Bk; 74.25.Ha; 74.80.Dm.
M. T. Beal-Monod and K. Maki, "Effect on High Tc Superconductivity of the a-b Anisotropy in the Normal Phase." Submitted to Phys. Rev. B. Laboratoire de Physique des Solides, Universite de Paris-Sud, Batiment 510, F-91405 Orsay Cedex, FRANCE; telephone +33 1 69 41 6928; telefax +33 1 69 41 6086; e-mail zazie@lps.u-psud.fr.
A. Beck, O. M. Froehlich, D. Koelle, R. Gross, H. Sato, and M. Naito, "La1.85Sr0.15CuO4-d Bicrystal Grain Boundary Josephson Junctions." To be published in Appl. Phys. Lett. Physikalisches Institut, Lehrstuhl Experimentalphysik II, Universitaet Tuebingen, Morgenstelle 14, D-72076 Tuebingen, GERMANY. 85.25.Cp; 74.50.+r; 85.70.-w.
V. Berseth, M. V. Indenbom, C. J. van der Beek, A. Erb, E. Walker, R. Fluekiger, and W. Benoit, "Instabilities of the Force-Free Current Configurations." Submitted to the XXI Int. Conf. on Low Temp. Phys. (LT21), Prague, Czech Republic, Aug. 8-14, 1996; to be published in Czechoslovak J. Phys. (1996). Institut de Genie Atomique, Department de Physique, Ecole Polytechnique Federale de Lausanne, CH-1015 Lausanne, SWITZERLAND.
A. Brazdeikis, A. S. Flodstroem, and I. Bryntse, "Effect of Thallium Oxide, Tl2O3 on the Formation of Superconducting HgBaCaCuO Films." To be published in Physica C (in press). Department of Physics, Materials Physics, Royal Institute of Technology, S-100 44 Stockholm, SWEDEN; telefax +46 8 249 131; e-mail audrius@matphys.kth.se.
E. Brecht, W. W. Schmahl, G. Miehe, M. Rodewald, H. Fuess, N. H. Andersen, J. Hanssmann, and Th. Wolf, "Thermal Treatment of YBa2Cu3xAlxO6+d Single Crystals in Different Atmospheres and NeutronDiffraction Study of Excess Oxygen Pinned by the Al Substituents." To be published in Physica C (in press). Fachbereich Materialwissenschaft, Strukturforschung, Technische Hochschule Darmstadt, D-64287 Darmstadt, GERMANY; telefax +49 7247 82 4494; e-mail brecht@infp.fzk.de. Key words: Cu-O chains, neutron diffraction, O-T transition, twin boundaries.
J. M. Chen, S. C. Chung, and R. S. Liu, "High-Resolution X-ray Absorption Near Edge Structure Studies of Monophasic Tl2Ba2Ca2Cu3O10-d (Tl-2223) Superconductor." To be published in Solid State Commun. (in press). Synchrotron Radiation Research Center (SRRC), Hsinchu, Taiwan, REPUBLIC OF CHINA. Key words: x-ray absorption near-edge structure, total x-ray fluorescence yield, total electron yield.
N. Chikumoto, N. Hayashi, H. Kojo, S. I. Yoo, M. Murakami, J. Yoshioka, S. Ozawa, and M. Otsuka, "Effect of Heat-Treatment on the Pinning Properties of Melt-Textured Re123." To be published in the Proc. of the Eighth Int. Workshop on Critical Currents in Supercond. (8th IWCC), Kitakyushu, Japan, May 27-29, 1996. Superconductivity Research Laboratory, International Superconductivity Technology Center (ISTEC), 16-25 Shibaura 1-chome, Minato-ku, Tokyo 105, JAPAN.
N. Chikumoto, K. Kishio, T. Kimura, T. Terai, and M. Konczykowski, "Matching Peaks Observed in La214 Single Crystals with Extended Defect Structure." To be published in the Proc. of the Eighth Int. Workshop on Critical Currents in Supercond. (8th IWCC), Kitakyushu, Japan, May 2729, 1996. Superconductivity Research Laboratory, International Superconductivity Technology Center (ISTEC), 16-25 Shibaura 1-chome, Minato-ku, Tokyo 105, JAPAN.
J. Chrosch, C. Panagopoulos, N. Athanassopoulou, J. R. Cooper, and E.K.H. Salje, "High-Resolution X-ray Diffraction Analysis of Magnetically Aligned High Tc Superconducting Ceramics." To be published in Physica C (in press). University of Cambridge, IRC in Superconductivity, Madingley Road, Cambridge CB3 0HE, UNITED KINGDOM; email jc10023@esc.cam.ac.uk.
C. S. Chuang and T. T. Chen, "Tunneling Spectroscopy of Pb-Au Junctions in the Transition From Tunneling to Contact Regime." To be published in Physica C (in press). Contact T. T. Chen, Department of Physics, National Tsing Hua University, Hsinchu 30043, Taiwan, REPUBLIC OF CHINA; telefax +886 35 723052.
M. Chung, D. T. Verebelyi, C. W. Schneider, M. V. Nevitt, M. J. Skove, J. E. Payne, M. Marone, and P. Kostic, "Characterization of Bi Based Superconducting Whiskers." To be published in Physica C (in press). Contact M. J. Skove, Department of Physics and Astronomy, Clemson University, Clemson, SC 29634.
J. W. Cochrane, A. Hartmann, and G. J. Russell, "Thermopower of UltraHigh Purity YBa2Cu3O7-d Single Crystals." To be published in Physica C, Vol. 262. Contact G. J. Russell, Advanced Electronic Materials Group, School of Physics, University of New South Wales, Sydney 2052, AUSTRALIA; telefax +61 2 663 3420.
T. Dahm and L. Tewordt, "Vertex Corrections for Dynamical Spin Susceptibility of the Hubbard Model and Comparison With Neutron Scattering on YBa2Cu3O6+x." To be published in Physica C, Vol. 262. Contact L. Tewordt, Abteilung fuer Theoretische Festkoerperphysik, Universitaet Hamburg, Jungiusstrasse 11, D-20355 Hamburg, GERMANY.
Alexandra Darulova, Paul Seidel, Stephan Beuven, and Marian Darula, "Phase-Locking Stability in Arrays of Josephson Junctions With MultiLoop Topology." Submitted to the XXI Int. Conf. on Low Temperature Physics (LT21), Prague, Czech Republic, Aug. 8-14, 1996; to be published in Physica B. Institut fuer Festkoerperphysik, Friedrich-SchillerUniversitaet, D-07743 Jena, GERMANY.
B. C. den Hertog and M. P. Das, "Aspects of the Normal State Phase of Copper Oxide Planes in High Tc Superconductors." Preprint #ANU-TP-19966; to be published in Phys. Rev. B. Department of Theoretical Physics, Research School of Physical Sciences and Engineering, Australian National University, Canberra ACT 2601, AUSTRALIA; e-mail bdh105@rsphysse.anu.edu.au. 74.25.Jb; 74.25.Kc; 71.27.+a.
J. Diederichs, A. K. Gangopadhyay, and J. S. Schilling, "Pressure Dependence of the Electronic Density of States and Tc in Superconducting Rb3C60." Quantum Design, 11578 Sorrento Valley Rd., San Diego, CA 92121.
H. Ding, T. Yokoya, J. C. Campuzano, T. Takahashi, M. Randeria, M. R. Norman, T. Mochiku, K. Kadowaki, and J. Giapintzakis, "Spectroscopic Evidence for a Gap in the Normal State of Underdoped High Tc Superconductors." To be published in Nature. Department of Physics, University of Illinois at Chicago, Chicago, IL 60607.
D. M. Eagles, M. Georgiev, and P. C. Petrova, "Explanation for the Temperature Dependence of Plasma Frequencies in SrTiO3 Using MixedPolaron Theory." Institute of Solid State Physics, Bulgarian Academy of Sciences, 72 Tzarigradsko Chaussee Boulevard, 1784 Sofia, BULGARIA. 71.38.+i; 71.45.Gm.
A. Erb, J.-Y Genoud, F. Marti, M. Daeumling, E. Walker, and R. Fluekiger, "Reversible Suppression of the So-Called Fishtail Effect in Ultra Pure Single Crystals of YBa2Cu3O7-d Achieved by Proper Oxygenation." To be presented at the Int. Conf. on Physics and Chemistry of Molecular and Oxide Superconductors (MOS'96), Karlsruhe, Germany, Aug. 2-6, 1996; to be published in the J. Low Temp. Phys. Departement de Physique de la Matiere Condensee, Universite de Geneve, 24 Quai Ernest-Ansermet, CH-1211 Geneve 4, SWITZERLAND; telephone +41 22 7026234; telefax +41 22 7026869; e-mail erb@sc2a.unige.ch. 74.60.Ge.
R. Fehrenbacher, "Coupling to Optical Phonons in the One-Dimensional t-J Model: Effects of Superconducting Fluctuations and Phase Separation." Max-Planck-Institut fuer Festkoerperforschung, Heisenbergstr. 1, D-70569 Stuttgart, GERMANY; e-mail rfehren@audrey.mpi-stuttgart.mpg.de. 74.20.Mn; 74.25.Kc; 71.27.+a; 71.38.+i.
V. G. Fleisher, R. Laiho, E. Laederanta, Yu. P. Stepanov, and K. B. Traito, "Temperature Dependence of the Magnetic Field Penetration Depth Versus Oxygen Ordering in Submicron YBCO Particles." To be published in Physica C (in press). Contact E. Laederanta, Wihuri Physical Laboratory, University of Turku, 20500 Turku, FINLAND; telefax +358 21 2319836; e-mail erlah@sara.cc.utu.fi. Key words: penetration depth, magnetization, oxygen stoichiometry, structural phase transition, glass state.
S. Friemel and C. Pasquier, "Activation Energies in the Vortex Liquid State of kappa-(BEDT-TTF)2Cu(NCS)2." To be published in Physica C (in press). Laboratoire de Physique des Solides, URA 2 CNRS, Universite Paris-Sud, F-91405 Orsay Cedex, FRANCE; telephone +33 1 69 41 53 58; email friemel@lps.u-psud.fr. Key words: organic superconductor, anisotropic superconductor, mixed state, electrical resistivity. 74.70.Kn; 74.60.Ec; 74.60.Ge.
Andrea Gauzzi and Julien Bok, "Importance of Out-of-Plane Dispersion of the Excitation Spectrum of Superconducting Bilayers With Josephson Coupling." To be published in J. Supercond. Laboratoire de Physique du Solide - UPR 5 CNRS, Ecole Superieure de Physique et Chimie Industrielles de la Ville de Paris, 10 rue Vauquelin, F-75231 Paris, FRANCE; telephone +33 1 40 79 44 10; telefax +33 1 40 79 44 25; e-mail gauzzi@hugo.espci.fr. 74.50.+r.
Yu. P. Gousev, A. D. Semenov, E. V. Pechen, A. V. Varlashkin, R. S. Nebosis, and K. F. Renk, "Coupling of Terahertz Radiation to a High-Tc Superconducting Hot Electron Bolometer Mixer." To be published in Appl. Phys. Lett. Institut fuer Angewandte Physik, Universitaet Regensburg, Universitaetsstr. 31; D-93040 Regensburg, GERMANY; telefax +49 941 943 4223; e-mail yurii.gousev@physik.uni-regensburg.de. 85.25.Jw; 85.60.Gz; 74.75.+t; 84.40.Hg.
R. Gross, D. Koelle, L. Alff, T. Bauch, A. Beck, R. Gerdemann, H. Haensel, and S. Weiss, "Physics and Application Potential of HTS VortexFlow Transistors." To be published in the Proc. of the Int. Workshop on Supercond., Iwate, Japan, June 24-27, 1996. II. Physikalisches Institut, Lehrstuhl fuer Angewandte Physik, Universitaet zu Koeln, Zuelpicher Strasse 77, D-50937 Koeln, GERMANY.
A. Gurevich, M. Benkraouda, and John R. Clem, "Vortices at Planar Defects in Layered Superconductors." Submitted to Phys. Rev. B, 1996. Applied Superconductivity Center, University of Wisconsin, Madison, WI 53706. 74.60.Ec; 74.80.Dm.
R. Henn, J. Kircher, and M. Cardona, "c-Polarized Vibrational Modes in La2CuO4 and La1.87Sr0.13CuO4 Determined by Ellipsometry." Submitted to Physica C. Max-Planck-Institut fuer Festkoerperforschung, Heisenbergstrasse 1, D-70563 Stuttgart, GERMANY; telephone +49 711 689 1728; telefax +49 711 689 1712; e-mail henn@cardix.mpi-stuttgart.mpg.de.
A. Hoffmann, J. Hasen, D. Lederman, T. Endo, Y. Bruynseraede, and Ivan K. Schuller, "Persistent Photoinduced Superconductivity." To be published in the Proc. of the E-MRS Spring Mtg. 1996, Strasbourg, France, June 4-7, 1996; to be published in the J. of Alloys and Compounds. Department of Physics 0350, University of California, 9500 Gilman Drive, La Jolla, CA 92093-0350; e-mail hoffmann@ucsd.edu. Key words: high-Tc superconductors, photoconductivity, thin film.
M. Houssa and M. Ausloos, "Thermal Conductivity of High-Tc Superconductors: Effect of Van Hove Singularities." To be published in Physica C. S.U.P.R.A.S., Institut de Physique B5, Universite de Liege, B-4000 Liege, BELGIUM; e-mail houssa@gw.unipc.ulg.ac.be. Key words: thermal conductivity, energy-gap symmetry, electronic structure, Van Hove singularity.
M. V. Indenbom, V. Berseth, C. J. van der Beek, W. Benoit, A. Erb, E. Walker, and R. Fluekiger, "Dynamics of the Force-Free Current Configurations." Submitted to the Eighth Int. Workshop on Critical Currents in Supercond. (8th IWCC), Kitakyushu, Japan, May 27-29, 1996. I.G.A., Ecole Polytechnique Federale de Lausanne, CH-1015 Lausanne, SWITZERLAND; indenbom@igahpse.epfl.ch.
M. V. Indenbom, C. J. van der Beek, V. Berseth, M. Konczykowski, F. Holtzberg, and W. Benoit, "Pinning-to-Barrier Crossover in YBa2Cu3O7-d Single Crystals." Submitted to the XXI Int. Conf. on Low Temperature Phys. (LT21), Prague, Czech Republic, Aug. 8-14, 1996, to be published in Czechoslovak J. Phys. (1996). I.G.A., Dept. de Physique, Ecole Polytechnique Federale de Lausanne, CH-1015 Lausanne, SWITZERLAND; indenbom@igahpse.epfl.ch.
E. Janod, R. Calemczuk, J.-Y. Henry, and J. Flouquet, "Magnetization as a Probe of the Pairing Symmetry in Bi2Sr2CuO6+d." Submitted to Physica C. CEA/Departement de Recherche sur la Physique de la Matiere Condensee SPSMS/LCP, 17 rue des Martyrs, F-38054 Grenoble Cedex 9, FRANCE; telefax +33 76 88 50 96; e-mail janod@drfmc.ceng.cea.fr. Key words: hightemperature superconductors, pairing symmetry, Bi-based cuprates, magnetization. 74.25.Bt; 74.72.Hs.
O. Jeandupeux, B. Heeb, and H. R. Ott, "A Note on the Temperature Dependence of the Magnetization of YBa2Cu3O6.9 and Bi2Sr2CaCu2O8 Close to Tc." To be published in Physica C (in press). Laboratorium fuer Festkoerperphysik, ETH-Hoenggerberg, CH-8093 Zurich, SWITZERLAND; e-mail jeandupeux@solid.phys.ethz.ch.
A. Jeremie and R. Fluekiger, "Similarities in Bi,Pb(2223) Formation Starting From Different Precursors." To be published in Physica C. Departement de Physique de la Matiere Condensee, Universite de Geneve, 24 quai Ernest-Ansermet, CH-1211 Geneve 4, SWITZERLAND; telephone +41 22 702 61 11; telefax +41 22 702 68 69; e-mail jeremie@sc2a.unige.ch. Key words: synthesis of Bi,Pb(2223), high-Tc superconductor, formation of Bi,Pb(2223) kinetic analysis.
G. Jung and B. Savo, "Elementary and Macroscopic Two Level Fluctuators in High-Tc Superconductors." To be published in J. Appl. Phys. (Sept. 1996). Department of Physics, Ben Gurion University of the Negev, P.O.B. 653, 84105 Beer-Sheva, ISRAEL; telephone +972 7 472124; telefax +972 7 281340; e-mail jung@bgumail.bgu.ac.il. 74.40.+k; 74.76.Bz; 74.50.+r; 74.60.Ge.
M. Karppinen, H. Yamauchi, and L. Niinistoe, "Studies on the Oxygen Stoichiometry in Superconducting Cuprates by Thermoanalytical Methods." To be published in J. of Thermal Analysis. Center for Ceramics Research, Research Laboratory of Engineering Materials, Tokyo Institute of Technology, Yokohama 226, JAPAN.
Edward Lewis, "Considerations About Plasmoid Phenomena and Superconductivity Phenomena." P.O. Box 13050, Chicago, IL 60613.
R. S. Liu, "Optimization of Superconducting Transition Temperature in the Tl-2223 and Tl/Pb-1223 Phases Via Adjusting Chemical Composition and Processing." To be published in the Proc. of the Symp. on HighTemperature Superconductors: Synthesis, Processing, and Large Scale Applications, Anaheim, CA, Feb. 4-8, 1996. Department of Chemistry, National Taiwan University, Taipei, Taiwan, REPUBLIC OF CHINA.
Wu Liu, T. W. Clinton, A. W. Smith, and C. J. Lobb, "Hall Conductivity Sign Reversal and Fluctuations in YBa2Cu3O7-d Films." Submitted to Phys. Rev. Lett. Center for Superconductivity Research, Department of Physics, University of Maryland, College Park, MD 20742. 74.60.Ge; 74.25.Fy; 72.40.+k.
G. Yu. Logvenov, H. Ito, T. Ishiguro, G. Saito, S. Takasaki, J. Yamada, and H. Anzai, "Anomalous Nernst Effect in the Mixed State of the TwoBand Organic Superconductors kappa-(BEDT-TTF)2Cu[N(CN)2]Br and kappa(BEDT-TTF)2Cu(NCS)2." To be published in Physica C (in press). Institute of Solid State Physics, Russian Academy of Science, Chernogolovka, Moscow District 142432, RUSSIA. Key words: organic superconductors, transverse thermomagnetic effect, magnetic flux motion.
Luciano Martini, "High Critical Current Densities in Silver-Sheathed Bi2223 Tapes." Submitted to Studies of High Temperature Supercond., Vol. 20, edited by A. V. Narlikar (Nova Science Publishers Inc., New York). CISE S.p.A., P. O. Box 12081, I-20134 Milan, ITALY; telephone +39 2 216 72303; telefax +39 2 216 72620; e-mail 0996mart@s1.cise.it.
N. Momono and M. Ido, "Evidence for Nodes in the Superconducting Gap of La2-xSrxCuO4 T^2 Dependence of Electronic Specific Heat and Impurity Effects." To be published in Physica C (in press). Department of Physics, Faculty of Science, Hokkaido University, Sapporo 060, JAPAN; email mom@s1.hines.hokudai.ac.jp. Key words: d-wave superconductor, energy gap, pair breaking, substitution effects, specific heat low T.
N. Morozov, E. Zeldov, D. Majer, and M. Konczykowski, "Paramagnetic ac Susceptibility at First-Order Vortex-Lattice Phase Transition." To be published in Phys. Rev. B (in press). Department of Condensed Matter Physics, Weizmann Institute of Science, 76100 Rehovot, ISRAEL.
Tomoyuki Naito, Terukazu Nishizaki, Fumiaki Matsuoka, Hideo Iwasaki, and Norio Kobayashi, "Vortex-Lattice Melting Transition in La1.85Sr0.15CuO4 Single Crystal." Submitted to the XXI Int. Conf. on Low Temperature Phys. (LT21), Prague, Czech Republic, Aug. 8-14, 1996. Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Sendai 980-77, JAPAN; e-mail naito@vostok.imr.tohoku.ac.jp.
G. Nakielski, M. Kaufmann, A. Ricketsen, M. Baumann, M. Schilling, G. Wirth, T. Amrein, and J. Koetzler, "Effects of Columnar Defects and Intrinsic Pinning on the Bose-Glass Transitions of YBa2Cu3O7 and Bi2Sr2CaCu2O8 Thin Films." Presented at the E-MRS Spring Conf., Strasbourg, France, June 4-7, 1996; to be published in J. Alloys and Compounds. Institut fuer Angewandte Physik, Universitaet Hamburg, Jungiusstr. 11, D-20355 Hamburg, GERMANY; telephone +49 40 41236728; telefax +49 40 41236368; e-mail nakielski@physnet.uni-hamburg.de.
K. K. Nanda, "Temperature Dependence of Upper Critical Field and Anisotropy of YBa2Cu3O7." To be published in Physica C (in press). Institute of Physics, Sachivalaya Marg, Bhubaneswar-751005, INDIA; email nanda@iopb.ernet.in. Key words: type-II superconductors, upper critical field H_[c2], specific heat at Tc.
O. Navarro, "Thermodynamic and Other Properties of the Superconductors BaPb0.7Bi0.3O3 and Ba0.7K0.3BiO3." To be published in Physica C (in press). Instituto de Investigaciones en Materiales, Universidad Nacional Autonoma de Mexico, Apartado Postal 70-360, 04510 Mexico D.F., MEXICO. Key words: electron-phonon coupling, Eliashberg equation, phonon mechanism.
David R. Nelson and Leo Radzihovsky, "Longitudinal Current Dissipation in Bose-Glass Superconductors." Department of Physics, Harvard University, Cambridge, MA 02138.
A. Niepel, C. Fink, and K. Kragler, "XPS Study of the Effects of 30 MeV [32]^S-ion Irradiation at T = 20 K on Ln2-xCexCuO4-d-Cuprates." To be published in Physica C (in press). Physikalisches Institut III, Universitaet Erlangen-Nuernberg, Erwin-Rommel Strasse 1, D-91058 Erlangen, GERMANY; telefax +49 91 31 15249.
Terukazu Nishizaki, Yasuaki Onodera, Tomoyuki Naito, Hidehito Asaoka, Humihiko Takei, and Norio Kobayashi, "Magnetic Phase Diagram and Vortex Pinning in YBa2Cu3Oy Single Crystals." Submitted to the XXI Int. Conf. on Low Temperature Phys. (LT21), Prague, Czech Republic, Aug. 8-14, 1996. Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Sendai 980-77, JAPAN; e-mail terukazu@ltp.imr.tohoku.ac.jp.
Terukazu Nishizaki, Yasuaki Onodera, Tomoyuki Naito, and Norio Kobayashi, "Anomalous Magnetization Due to the Vortex Lattice Melting Transition in YBa2Cu3Oy." Submitted to the Int. Conf. on Phys. and Chem. of Molecular and Oxide Supercond. (MOS'96), Karlsruhe, Germany, August 2-6, 1996. Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Sendai 980-77, JAPAN; e-mail terukazu@ltp.imr.tohoku.ac.jp. 74.60.Ge; 74.60.Jg.
Terukazu Nishizaki, Takahiko Sasaki, Tetsuo Fukase, and Norio Kobayashi, "Anomalous Magnetization and Dimensional Crossover of the Vortex System in the Organic Superconductor kappa-(BEDT-TTF)2Cu(NCS)2." To be published in Phys. Rev. B. Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Sendai 980-77, JAPAN; e-mail terukazu@ltp.imr.tohoku.ac.jp. 74.70.Kn; 74.60.Ge; 74.60.Jg.
Hannes Nowak, Steffen Brabetz, Frank Giessler, Jens Haueisen, Ralph Huonker, Uwe Leder, Roland Weidl, Lars Doerrer, Paul Seidel, and Siegfried Mueller, "Magnetocardiography with High and Low Tc SQUIDGradiometer Devices." To be published in the Proc. of the 10th NordicBlatic Conf. Biomedical Engineering and 1st Int. Conf. Bioelectromagnetism, Tampere, Finland, June 9-13, 1996. Biomagnetic Centre, Department of Neurology, University Hospital, Friedrich Schiller University Jena, Philosophenweg 3, D-07743 Jena, GERMANY.
A. Oota, T. Fukunaga, and M. Matsui, "ac Transport Losses of Textured Ag-(Bi,Pb)2Sr2Ca2Cu3Ox Tapes." To be published in Physica C (in press). Toyohashi University of Technology, Tempaku-cho, Toyohashi, Aichi 441, JAPAN; telephone +81 532 44 6732; telefax +81 532 48 3422; e-mail oota@eee.tut.ac.jp.
F. J. Owens, Z. Iqbal, and D. Kirven, "Anomalous Microwave Absorption in Quasi-One-Dimensional (Sr,Ca)14Cu24O41." To be published in Physica C (in press). Army Armament Research, Development and Engineering Center, Picatinny, NJ 07806.
C. Panagopoulos, J. R. Cooper, N. Athanassopoulou, and J. Chrosch, "The Effects of Zn Doping on the Anisotropic Penetration Depth of YBa2Cu3O7." Submitted to Phys. Rev. B. Interdisciplinary Research Centre in Superconductivity, University of Cambridge, Madingley Road, Cambridge CB3 0HE, UNITED KINGDOM; telephone +44 1223-337076 or -337046; telefax +44 1223-337074; e-mail cp200@hermes.cam.ac.uk. 74.72.Bk; 74.62.Dh; 75.30.Gw; 74.40.+k.
C. Panagopoulos, W. Zhou, N. Athanassopoulou, and J. R. Cooper, "Surface-Quality Dependence of the Low Temperature Magnetization of YBa2Cu3O7." Submitted to Physica C. Interdisciplinary Research Centre in Superconductivity, University of Cambridge, Madingley Road, Cambridge CB3 0HE, UNITED KINGDOM; telephone +44 1223-337076 or -337046; telefax +44 1223-337074; e-mail cp200@hermes.cam.ac.uk. Key words: magnetization, penetration depth, HREM, d-wave superconductor.
D. Pelloquin, A. Maignan, A. Guesdon, V. Hardy, and B. Raveau, "Single Crystal Study of the '1201' Superconductor Hg0.8Bi0.2Ba2CuO4+d." To be published in Physica C (in press). Laboratoire CRISMAT, URA CNRS 1318, ISMRA, Bd. du Marechal Juin, F-14050 Caen Cedex, FRANCE.
A. Pfuch, F. Schmidl, A. Wiese, L. Doerrer, U. Huebner, and P. Seidel, "Fabrication of Different Kinds of Josephson Junctions Based on BSCCO2212 and TBCCO-2212 Thin Films." To be published in the Proc. of the 3rd HTS Workshop on Digital Applications, Josephson Junctions and 3Terminal Devices, Enschede, The Netherlands, April 21-23, 1996. Institut fuer Festkoerperphysik, Friedrich-Schiller-Universitaet Jena, Lessingstr. 8, D-07743 Jena, GERMANY. Key words: thin BSCCO films, BSCCO biepitaxial and bicrystalline Josephson junctions, BSCCO magnetic penetration depth, intrinsically stacked thin-film Josephson junctions (BSCCO, TBCCO).
Warren E. Pickett, "Single Spin Superconductor." Naval Research Laboratory, Washington, DC 20375-5345; telephone (202) 404-8631; telefax (202) 404-7546; e-mail pickett@dave.nrl.navy.mil.
M. Qvarford, S. Soederholm, O. Tjernberg, G. Chiaia, H. Nylen, R. Nyholm, I. Lindau, U. O. Karlsson, and H. Bernhoff, "X-ray Absorption Study of Oxygen in the High-Tc Superconductor Bi2Sr2CaCu2O8 Near the Interfaces to Cu, Ag and Au." To be published in Physica C (in press). Department of Synchrotron Radiation Research, Institute of Physics, Lund University, Box 118, S-221 00 Lund, SWEDEN; telefax +46 46 222 42 21; email mats.qvarford@sljus.lu.se. Key words: Cu-O planes, hole concentration, metal overlayer, normal-state properties, XAFS.
R. Ravinder Reddy and P. Venugopal Reddy, "An Analytical Study of Young's Moduli of HTSC at Low Temperatures." To be published in Physica C (in press). Contact P. Venugopal Reddy, Department of Physics, Osmania University, Hyderabad-500 007, INDIA; telefax +91 40 869 020.
J. A. Schlueter, J. M. Williams, A. M. Kini, U. Geiser, J. D. Dudek, M. E. Kelly, J. P. Flynn, D. Naumann, and T. Roy, "New Directions in the Synthesis and Exploration of Novel Organic Superconductors: Inverse Isotope Effect in the Organic Superconductor kappa_L-(ET)2Ag(CF3)4(1Bromo-1,2 Dichloroethane) [ET = Bis(Ethylenedithio)Tetrathiafulvalene]." To be published in Physica C (in press). Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439; telefax (708) 252-9595; email janice_coble@qmgate.anl.gov.
Friedhelm Schoenfeld, Arno P. Kampf, and Erwin Mueller-Hartmann, "TwoMagnon Raman Scattering in a Spin Density Wave Antiferromagnet." Institut fuer Theoretische Physik, Universitaet zu Koeln, Zuelpicher Str. 77, D-50937 Koeln, GERMANY; telephone +49 221 470 4208; telefax +49 221 470 5159; e-mail fsch@thp.uni-koeln.de. 75.30.Ds; 75.30.Fv; 76.50.+g.
P. Seidel, S. Linzen, F. Schmidl, and R. Cihar, "High-Tc SQUIDS on Silicon Substrates." Submitted to Les Editions de Physique and to the Proc. of the 2nd European Workshop on Low Temperature Electronics (WOLTE2), Leuven, Belgium, June 26-28, 1996. Institut fuer Festkoerperphysik, Friedrich-Schiller-Universitaet Jena, Lessingstr. 8, D-07743 Jena, GERMANY.
Paul Seidel, Andreas Pfuch, Frank Schmidl, Jens Scherbel, and Uwe Huebner, "Thin Film Series Arrays of Intrinsic Josephson Junctions." Submitted to the XXI Int. Conf. on Low Temperature Physics (LT21), Prague, Czech Republic, Aug. 8-14, 1996; to be published in Physica B. Institut fuer Festkoerperphysik, Friedrich-Schiller-Universitaet Jena, Lessingstr. 8, D-07743 Jena, GERMANY.
U. Staub and C. Ritter, "Two Dimensional Spin Fluctuations of Ho^[3+] in HoBa2Cu3O7." To be published in Phys. Rev. B. Swiss Light Source Project, Paul Scherrer Institute, CH-5232 Villigen PSI, SWITZERLAND; telephone +41 56 310 44 94; telefax +41 56 310 31 51; e-mail urs.staub@psi.ch. Key words: short-range order, crystal-field, other cuprates (high-Tc superconductors). 75.40.-s; 71.70.Ch; 74.72.Jt.
Minoru Takemoto, Naoki Ohashi, Takaaki Tsurumi, Osamu Fukunage, and Junzo Tanaka, "Temperature Dependence of Hall Angle in Superconducting La1.85-xNdxCa1.15Cu2O6-d." To be published in Physica C (in press). Department of Inorganic Materials, Faculty of Engineering, Tokyo Institute of Technology, 2-12-1 O-okayama, Meguro, Tokyo 152, JAPAN.
Carsten Timm, "Generalization of the Berezinskii-Kosterlitz-Thouless Theory to Higher Vortex Densities." To be published in Physica C (in press). Institut fuer Theoretische Physik, Universitaet Hamburg, Jungiusstrasse 9, D-20355 Hamburg, GERMANY; telephone +49 40 4123 2427; telefax +49 40 4123 6798; e-mail timm@physnet.uni-hamburg.de.
N. Vandewalle and M. Ausloos, "Inner Patterns and Front Propagation of a Dynamic Random Impurity Model." To be published in Phys. Rev. Lett. S.U.P.R.A.S., Institut de Physique B5, Sart-Tilman, Universite de Liege, B-4000 Liege, BELGIUM; e-mail vandewal@gw.unipc.ulg.ac.be. 05.40.+j; 61.43.Hv; 64.40.Ak.
R. P. Vasquez, Z. F. Ren, and J. H. Wang, "Electronic Structure of Tl2Ba2CuO6+d Epitaxial Films Measured by X-ray Photoemission." To be published in Phys. Rev. B (Sept. 1, 1996). Center for Space Microelectronics Technology, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109-8099. 74.72.Fq; 74.25.Jb; 74.76.Bz; 79.60.-i.
N. Vilalta, F. Sandiumenge, E. Rodriguez, B. Martinez, S. Pinol, X. Obradors, and J. Rabier, "Microstructure, Irreversibility Line and Flux Dynamics in Plastically Deformed Directionally Solidified YBa2Cu3O7." Submitted to Phil. Mag. B, 1996. Institut de Ciencia de Materials de Barcelona (C.S.I.C.), Campus de la Universitat Autonoma de Barcelona, 08193 Bellaterra, Catalunya, SPAIN.
N. V. Vo, A. J. Bourdillon, C. C. Neo, S. X. Dou, and H. K. Liu, "Thermal Stability in High-Tc Coil and Magnet Design by Processing Control of Bi(Pb)-2223/Ag Multifilamentary Tapes." Submitted to J. Supercond. Centre for Superconducting and Electronic Materials, University of Wollongong, Northfields Ave., Wollongong NSW 2522, AUSTRALIA. Key words: multifilamentary tapes, Bi(Pb)-2223/Ag coils, thermal stability, fill factor, intermediate deformation.
L. Winkeler, S. Sadewasser, B. Beschoten, H. Frank, F. Nouvertne, and G. Guentherodt, "Interlayer Coupling in Pb-Substituted Bi2Sr2CaCu2O8+d Single Crystals." To be published in Physica C (in press). 2. Physikalisches Institut, RWTH Aachen, D-52056 Aachen, GERMANY.
Y. Yeshurun, Alexis P. Malozemoff, and A. Shaulov, "Magnetic Relaxation in High Temperature Superconductors." To be published in Rev. Mod. Phys. (July 1996). Center for Superconductivity, Department of Physics, Bar-Ilan University, Ramat-Gan 52100, ISRAEL.
X. F. Zhang, Y. S. Sung, D. J. Miller, B. J. Hinds, R. J. McNeely, D. L. Studebaker, and T. J. Marks, "New Structural Aspects of Tl2Ba2CaCu2Oy Epitaxial Thin Films Grown by MOCVD on LaAlO3." Submitted to Physica C. Materials Science Division and the Science and Technology Center for Superconductivity, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439; telephone (630) 252-4764; telefax (630) 252-7777; email xiaofeng_zhang@qmgate.anl.gov. Key words: Tl2Ba2CaCu2Oy superconducting thin film, microstructure. 61.16.Bg; 61.50.Em; 68.55.Jk.
*Aug. 5 - 8, 1996: Workshop on Fluctuation Phenomena in HTSC, International Centre for Theoretical Physics, Trieste, Italy. Three main fields of fluctuation phenomena in superconductors will be discussed: order parameter fluctuations above Tc, phase fluctuations in the vicinity of Kosterlitz-Thouless transitions, and quantum and thermal fluctuations of vortices in HTSC. Topics to be covered include transport properties in the ab plane and along the c axis, effect of fluctuations on the Knight shift and the NMR relaxation rate, calculations of superconducting fluctuations beyond a BCS approach, effect of fluctuations on tunneling phenomena, specific role of the density of states fluctuation in HTSC, fluctuation effect as a probe for the type of symmetry of the order parameter, effect of magnetic field on fluctuation phenomena for static and transport properties, and others. Workshop open to all researchers from countries that are members of UN, EEAC, IAEA, NATO, or UNESCO. No registration fee. "Request for Participation" form obtainable via e-mail from smr860@ictp.trieste.it and typing "get index" on subject line or via gopher server at gopher.ictp.trieste.it. Forms should be mailed to Adriatico Research Conferences, International Centre for Theoretical Physics, P.O. Box 586, I-34100 Trieste, Italy.
*Sept. 9 - 11, 1996: High Temperature Superconductivity 10, St. Andrews University, St. Andrews, Scotland, UK. Tenth annual meeting in the series. Invited speakers include: J. D. Jorgensen (Argonne), E. Kaldis (ETH Zurich), M. P. Day (The Royal Institution), M. T. Weller (Southampton), S. Lee (St. Andrews), and J. P. Attfield (Cambridge). Oral and poster contributions on the topics of synthesis, structure, characterization, properties, applications and theory of hightemperature superconductors and related materials. Cost for registration, lunch, dinner, bed and breakfast from Sept. 9 -11 is 105 Pounds for full participants. For further information contact John T. S. Irvine or P. Lightfoot, School of Chemistry, St. Andrews University, St. Andrews, Fife KY16 9ST; telephone +44 1334 463817; telefax +44 1334 463808; email jtsi@st-and.ac.uk.
*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.
Sept. 30 - Oct. 2, 1996: Swiss Workshop on Superconductivity and Novel Metals: Basic Research and Applications, Les Diablerets, Switzerland. Supported by the Swiss National Science Foundation. Objectives are to bring together researchers in basic and applied superconductivity and neighboring fields and to act as a forum for promoting research and applications of superconductivity and novel metals. Workshop will also celebrate the 10th anniversary of the discovery of high-temperature superconductivity. Papers are solicited in the following topics: highand low-temperature superconductors; novel metals; materials science and new materials; crystal growth, thin films, and multilayers; spectroscopies; experiments probing the nature of the superconducting state; phenomenology and microscopic theory; flux dynamics, flux pinning, and critical currents; and applications including magnets and electric energy systems, electronics, and microwave applications. Oral and poster sessions. Workshop is open to all scientists, engineers, and students working in the field in Switzerland and a limited number of invited scientists from other countries. Abstract and preregistration deadline, July 22, 1996. For further information, contact Claus Schueler, ABB Konzernforschung, 5405 Baden-Daettwil, Switzerland; telephone +41 56 486 8136; telefax +41 56 493 3662; e-mail claus.schueler@chcrc.abb.ch.
*Oct. 1 - 4, 1996: Eighth National Congress on High Temperature Superconductivity (SATT 8), Como, Villa Olmo, Italy. Organized by CISE SpA, CNR-ITM, INFN-LASA, Pirelli Cavi SpA, and University of Milano. Aim is to discuss the latest developments on high-Tc and conventional superconductors, and to promote dialogue and cooperative activities among the national groups. Oral and poster sessions classified among the following themes: (1) superconducting materials and associated technologies; (2) electronic, optical, and acoustic spectroscopies; (3) electric, magnetic, mechanical, and thermal properties; (4) dynamics and pinning of fluxoids, and dissipative phenomena; (5) theories and mechanisms of HTS; (6) Josephson effect and devices; and (7) applications. Abstract deadline, July 10, 1996. Papers to be refereed and published in a special issue of Nuovo Cimento D. For further information, contact SATT 8 Secretariat, Centro di Cultura Scientifica "A. Volta," Villa Olmo, Via Cantoni, I-22100 Como, Italy; telephone +39 31-572213; telefax +39 31-573395; e-mail congress@icil64.cilea.it. Information also available at the homepage http://www.pirelli.com/village/news/news/news.htm.
*Oct. 21 - 24, 1996: 9th International Symposium on Superconductivity (ISS'96), Sapporo, Hokkaido, Japan. Organized by the International Superconductivity Technology Center (ISTEC). Symposium will consist of oral and poster sessions and invited talks in the following fields of superconductivity: physics -- theory, physical properties, and new measurement techniques; chemistry -- new materials and syntheses, substitution, solid-state chemistry, and properties; flux pinning -- mechanism and electromagnetic properties of fluxoids; wires, tapes, and bulk -- solid-state powder ceramics, chemical-solution processing, melting solidification, and chemical-vapor deposition; thin films -- processing, properties, and lithography; device applications -- digital, analog, SQUID, and other electronic devices; system applications -- power, power transportation, magnets, magnetic shields, and other system applications. Papers are solicited. Abstract deadline, June 30, 1996; preregistration deadline, September 30, 1996. Papers will be published. Official language is English. For further information, contact ISS'96 Secretariat, ISTEC, Eishin Kaihatsu Bldg. 6F, 34-3 Shimbashi 5-chome, Minato-ku, Tokyo 105, Japan, telephone +81 3 3431-4002; telefax +81 3 3431-4044; e-mail chyoki@istec.mxa.meshnet.or.jp.
*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.
Jan. 12 - 17, 1997: Gordon Research Conference on Superconductivity, Colony Harbor Hotel, Ventura, CA. Program thus far includes invited speakers who will discuss the following topics: basic theory, vortices, materials, photoemission, optical properties, d-wave and s-wave superconductivity, normal-state properties, charge and flux quantization, stripe phases, tunneling, and nickel borides. Both oral and poster sessions are included and abstracts are requested for poster papers. Requests for registration forms and abstracts should be sent to Gordon Research Conferences, University of Rhode Island, P.O. Box 984, West Kingston RI 02892-0984, telefax (401) 783-7644; e-mail app@grcmail.grc.uri.edu. For further information, contact D. K. Finnemore, Ames Laboratory-USDOE and Department of Physics, Iowa State University, Ames, IA 50011-3160; telephone (515) 294 3455; telefax (515) 294-0689; e-mail finnemore@ameslab.gov.
Jan. 12 - 17, 1997: Gordon Research Conference on Superconductivity, Colony Harbor Hotel, Ventura, CA. Program thus far includes invited speakers who will discuss the following topics: basic theory, vortices, materials, photoemission, optical properties, d-wave and s-wave superconductivity, normal-state properties, charge and flux quantization, stripe phases, tunneling, and nickel borides. Oral and poster sessions. For further information, contact D. K. Finnemore, Ames Laboratory-USDOE and Department of Physics, Iowa State University, Ames, IA 50011-3160; telephone (515) 294 3455; telefax (515) 294-0689; e-mail finnemore@ameslab.gov.
*March 6 - 8, 1997: International Workshop on Critical Currents in Superconductors for Practical Applications (SPA '97), Xi'an, China. Satellite conference to the Fifth International Conference on Materials and Mechanisms of Superconductivity (M2S-HTSC-V) at Beijing. SPA'97 will concentrate on improvement of practical superconducting materials and their applications. Main topics are synthesis and processing of practical materials; properties of high-Tc tapes, cables, coils, and bulk materials; critical currents and microstructures; flux dynamics and pinning mechanisms; applications of high-Tc and low-Tc materials; processing and physical properties of high-Tc films; and applications of high-Tc films. Conference language is English. Abstract deadline, December 1, 1996; authors notified of acceptance by January 1, 1997. For information, contact P. X. Zhang, Conference Secretary, SPA '97, Northwest Institute for Nonferrous Metal Research, P.O. Box 51, Xi'an, Shaanxi 710016, People's Republic of China; telephone +86 29 6231079; telefax +86 29 6231103; e-mail pxzhang@xjtu.edu.cn.
*March 6 - 8, 1997: International Workshop of 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 further information, contact LI XiaoGuang, 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.
*July 27- Aug. 1, 1997: International Cryogenic Engineering Conference and the International Cryogenic Materials Conference (Joint ICMC-CEC 1997 Conference), Oregon Convention Center, Portland, OR. Intended for those interested in cryogenic applications of engineering and materials. Includes special focus on superconductivity (LTS and HTS). CEC focuses on science and engineering required for cryogenic applications. Examples of topics in past conferences include liquified gases for fuels; space applications of cryogenic liquids; cooling and performance of superconducting magnet systems in medical, transportation, power, and basic research applications; as well as the systems, machinery, control technology, and thermodynamics required to produce low temperatures. ICMC focuses on the development, characterization, fabrication, and optimization of the materials used in cryogenic applications. ICMC is typically broken into two broad categories: structural materials and superconducting materials. Covers both high- and low-temperature superconducting materials from basic materials research to behavior of composite cables and wires in applications. Cryo Expo will be held in conjunction with conference. Abstract deadline, December 20, 1996. For further information, contact Bill Warnes, Oregon State University, Mechanical Engineering Dept., Corvallis, OR 97331-6001; telephone (541) 737-7016; e-mail warnesw@engr.orst.edu; or Nancy Wilson, Exe-Me and Company, P.O. Box 25445, Portland, OR 97298-0445; telephone (503) 2922114; e-mail ewemeco@europa.com. Information also available at the web site http://www.orst.edu/groups/icmc97.
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High-Tc Update, Vol. 10, #13, July 1, 1996.