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Junctions

A complete scenario of high-Tc superconductivity based on experimental data from electron-tunneling spectroscopy on break junctions in underdoped, overdoped, and Ni-doped Bi2Sr2CaCu2O8+d (Bi-2212) single crystals over the temperature range 14-290 K is proposed by A. Mourachkine (Brussels). Below Tc, the author observed four different gaps: (a) a spin-density-wave (SDW) gap due to antiferromagnetic correlations, (b) a superconducting gap due to spinon-up - spinon-down pairing, (c) a d-wave superconducting gap, and (d) a small superconducting gap most likely having g-wave symmetry. The author finds that d-wave superconductivity is mediated by spin waves and that the magnitude of the superconducting gap due to pairing of spinons most likely has s-wave symmetry. The maximum magnitudes of the SDW, spinon, and d-wave gaps are located at (pi/2,pi/2), (pi/2,pi/2), and (pi,0), respectively.

The behavior of a Josephson junction in which two BCS superconductors are coupled through an Anderson impurity has been analyzed nonperturbatively by A. V. Rozhkov and D. P. Arovas (UC-San Diego). The authors recover earlier perturbative results that a d = pi phase difference is preferred when the impurity is singly occupied and the on- site Coulomb interaction is large. They also find a novel intermediate phase in which either d = 0 or d = pi is stable, while the other is metastable and the energy E(d) has a kink for d between 0 and pi. As a consequence, the current-voltage (I-V) characteristics of the junction are modified at low voltages.

A preprint by T. Loefwander et al. (Chalmers University of Technology and Goeteborg University) reports a theoretical study of the ac Josephson effect in voltage-biased planar junctions of d-wave superconductors. For some orientations of the superconductors a current peak is found at finite voltage in the I-V characteristics. The authors show that a midgap state acts as a resonance and produces the peak. The authors also present a possible explanation for the zero-bias conductance peak, recently found in experiments on grain-boundary junctions of high-temperature superconductors, in terms of resonant transmission via a midgap state of quasiparticles undergoing multiple Andreev reflections. Two additional preprints from the same institutions, one by N. I. Lundin et al. and the other by G. Johansson et al., analyze further effects of Andreev reflections upon the properties of voltage-biased superconducting junctions.

A theory of spin- and charge-transport properties of ferromagnet/insulator/d-wave-superconductor (F/I/S) junctions has been developed by S. Kashiwaya (Stanford and ETL) et al. The authors present a formulation that gives the spin current and charge current as a function of the applied voltage and spin polarization of the ferromagnet for arbitrary barrier heights. Surface bound states are found not to contribute to the spin current. The authors also clarify several anomalous properties of Andreev reflection at the interface due to the exchange field.

Measurements of the surface impedance of Nb/CuMn (superconducting/spin- glass) bilayers at 10 GHz obtained using a parallel-plate resonator have been carried out by L. V. Mercaldo (Maryland) et al. to study the order parameter in superconducting/magnetic proximity systems. The authors find that the data differ strongly from the superconducting/normal-metal case, showing the magnetic nature of the CuMn layer, which acts as a weak ferromagnet.

As noted in a preprint by H. Grabert (Freiburg) and G.-L. Ingold (Augsburg and Saclay), in the classical Josephson effect, the phase difference across the junction is well defined, and the supercurrent is reduced only weakly by phase diffusion. For mesoscopic junctions with small capacitance, however, the phase undergoes large quantum fluctuations, and the current is also decreased by Coulomb blockade effects. The authors theoretically describe the behavior of the I-V characteristics of such junctions over a wide range of parameters, and they study the transition from the phase-diffusion regime with coherent Josephson current to the Coulomb-blockade regime, which shows a supercurrent peak due to incoherent Cooper-pair tunneling.

Vortices

Transport measurements in fixed applied field have been made by S.F.W.R. Rycroft (IRC-Cambridge) et al. on Bi2Sr2CaCu2O8+d (Bi-2212) single crystals in the Corbino disk geometry, where vortices travel in circles and do not cross the sample edges. The authors compared the results directly with the standard striplike geometry by cutting the disk into a strip and remeasuring the sample using the same electrical contacts. Pronounced differences were observed in measurements of both the resistive transition and the I-V characteristics in these two geometries. The critical current density in the vortex-solid phase is shown to be at least 20 times smaller than usual estimates for the strip geometry. The authors conclude that the transport properties of Bi-2212 samples in the strip geometry are dominated by surface barriers in both the solid- and liquid-vortex phases over a wide range of fields and temperatures.

The three-dimensional uniformly frustrated XY model has been used by P. Olsson (Umea) and S. Teitel (Rochester) to model a high-temperature superconductor in an applied magnetic field and to explicitly measure the longitudinal correlation length xi_z in the vortex-line-liquid phase. The authors determined the scaling of xi_z with magnetic field and system anisotropy close to the vortex-lattice melting transition. The authors also applied their results to determine the extent of longitudinal correlations in YBa2Cu3O7-d (YBCO) just above melting.

Details of flux-line-lattice melting in anisotropic high-Tc superconductors in B||c have been studied by Y. Nonomura et al. (NRIM) using Monte Carlo simulations of the 3D frustrated XY model. The authors found that the percentage of entangled flux lines abruptly changes at the melting temperature T_m, while no sharp changes were found in the number of loop excitations around T_m. The authors conclude that the origin of the melting transition is the entanglement of flux lines. The authors find that the Lindemann number is c_L ~~ 0.30 independent of anisotropy, which confirms the validity of the Lindemann criterion for this melting transition.

A preprint by B. Y. Zhu (Nanjing and Beijing) et al. reports numerical solutions of the overdamped equation of vortex motion in a two- dimensional driven vortex lattice with disordered pinning, in which the driving Lorentz force, the pinning force due to point defects, the intervortex interaction force, and the thermal fluctuation force are all taken into account. The authors report the different conditions under which first-order melting transitions or second-order glass transitions are observed.

The angular dependence of the c-axis magnetoresistance rho_c(B) of Bi- 2212 irradiated with heavy ions has been studied by N. Morozov (Los Alamos) et al. The authors found that at temperatures near 68 K, the scaling of rho_c(B) with the c-axis magnetic field component B_[perp.] is broken, and the in-plane field B_[parallel] affects rho_c. At this temperature, at a specific field B_[cr] ~~ B_[phi]/2, the magnetoresistance becomes independent of field orientation. This crossing point allowed the authors to estimate the correlation length L of pancake positions along the c axis. The authors found L/s ~ 60 at B = B_[cr], where s is the interlayer space. The authors emphasize that this provides evidence of strong enhancement of pancake alignment in the vortex liquid in crystals with columnar defects.

As noted in a preprint by M. A. Moore (Manchester) and A. Perez-Garrido (Murcia), vortices in thin-film superconductors are often modeled as a two-dimensional system of particles interacting via a repulsive logarithmic potential. The authors present arguments showing that the Abrikosov crystalline state is unstable at any finite temperature against proliferation of screened disclinations. The authors find that the correlation length of crystalline order grows as T^[-1/2] as the temperature is reduced to zero, in excellent agreement with their simulations.

The effect of vortices on quasiparticle transport in cuprate superconductors has been investigated by M. Chiao et al. (McGill) in measurements of the low-temperature thermal conductivity of YBa2Cu3O6.9 in magnetic fields up to 8 T. The residual linear term (as T --> 0) is found to increase with field, directly reflecting the occupation of extended quasiparticle states. A study for different Zn impurity concentrations reveals good agreement with calculations for d-wave superconductors, which sheds light on the nature of scattering by both impurities and vortices.

A preprint by R. P. Huebener et al. (Tuebingen) presents a phenomenological discussion of the origin of two intrinsic steps recently observed in the flux-flow resistance of the cuprate superconductor Nd2-xCexCuO4. The explanation involves two characteristic energies, the minigap epsilon_0 for states in the vortex core and the superconducting energy gap parameter Delta.

Detailed measurements of the electronic specific heat C(H) in the s-wave superconductor NbSe2, which has been predicted to be proportional to the magnetic field H, are reported by J. E. Sonier (Los Alamos) et al. At low magnetic fields, the authors observed a downward curvature similar to that reported in high-Tc superconductors, where such behavior has been attributed to d_[x^2-y^2]-wave symmetry. In NbSe2, the authors find that the low-field anomaly in C(H) is well accounted for by the expansion of the vortex cores recently measured by muSR. The result provides a simple explanation for puzzling reports of H^[1/2] behavior for C(H) in s-wave superconductors.

RBa2Cu3O7-d

Measurements of the temperature-dependent [63]^Cu NMR spin-lattice relaxation rate for near optimally doped YBa2Cu3O7-d (YBCO), near and above Tc, are reported by K. Gorny (Ohio State) et al. in magnetic fields of 0 T, 8.8 T, and 14.8 T. In sharp contrast to previous work, the authors find no magnetic field dependence. The authors discuss experimental issues arising in measurements of this required precision, and they discuss the implications of their experiment with regard to the spin gap or pseudogap. For example, in a scenario involving dynamical pairing correlations or preformed pairs, the results call for relatively large energy scales and short length scales.

Three papers in this issue report results from time-resolved femtosecond optical spectroscopy bearing upon the evolution of the gap structure with doping in YBa2Cu3O7-d. Two papers by D. Mihailovic (Ljubljana) et al. and one by J. Demsar (Ljubljana) et al. find that the underdoped state is characterized by a temperature-independent energy gap E_g, which exists at all temperatures and has a magnitude that appears to be inversely proportional to doping. This implies the existence of preformed pairs. Close to optimum doping, another gap simultaneously becomes visible; this gap has a BCS-like temperature dependence and closes at Tc.

A preprint by C. Bernhard (MPI-Stuttgart) et al. reports that the far- infrared electronic c-axis conductivity sigma_[1c]^[el] of underdoped to overdoped Y1-xCaxBa2Cu3O7-d crystals has been studied by ellipsometry. The authors report that the peculiar temperature and frequency dependence of sigma_[1c]^[el], including the appearance of the normal- state gap, are determined by the CuO2 planes and their hole-doping state. In addition, the authors find that the spectral gap in the c- axis conductivity exhibits a very similar temperature and doping dependence to the gap that has been observed by angle-resolved photoemission experiments around the X point of the 2D Brillouin zone (the so-called hot spots). This finding suggests that the c-axis transport may be determined mainly by the carriers around the hot spots.

An extensive study of the field and temperature dependence of the critical current density Jc(B,T) for a flux-grown NdBa2Cu3O7-d (NBCO) single crystal and melt-textured samples of NBCO and YBCO are reported by T. Higuchi (Railway Technical Research Institute and SRL-ISTEC) et al. The authors identify regimes in B-T space where different pinning mechanisms are dominant.

A preprint by T. Kimura (Nagoya Institute of Technology) et al. reports measurements of the transport critical current density Jc(B,T) of filamentary NBCO prepared by a solution-spinning method using an aqueous solution of mixed acetates of Nd, Ba, Cu, polyvinyl alcohol, and organic acids. The highest values of Jc, 3.5 x 10^4 A/cm^2 at 77 K and 0 T and more than 10^4 A/cm^2 at 77 K and 2 T, were achieved for Nd1.18Ba2.12Cu3.09O7-d by controlling the oxygenation conditions.

Volume pinning forces F_p = JcB measured at different temperatures in NdBa2Cu3O7-d (NBCO) have been found by M. R. Koblischka et al. (SRL- ISTEC) to scale as functions of b_f = B_a/B_[fp] or h = H_a/H_[irr] (B_a or H_a = applied field, B_[fp] = peak position of F_[p,max], and H_[irr] = irreversibility field). The authors use this procedure to make estimates of F_[p,max], B_[fp], and H_[irr] at zero temperature.

A preprint by P. Schaetzle et al. (Dresden) reports the development of a melt-crystallization process with reduced processing temperatures and process times to produce YBCO/Ag monoliths (diameter 26 mm) with a homogeneous distribution of small Ag inclusions. The mechanical properties are improved, but the superconducting properties at 77 K (trapped flux density B_0 = 480 mT and levitation force F_N = 40 N) are slightly reduced compared with YBCO monoliths without Ag additions (750 mT and 65 N). The maximum trapped flux, however, increased to the value B_0 = 9.4 T at 26.5 K instead of 8.4 T in the Ag-free bulk monolith.

Custom-shaped monoliths of YBCO have been produced by M. Ullrich et al. (Goettingen) by applying the top-seeded-melt-growth (TSMG) method. The trapped magnetic induction at 77 K usually exceeds 600 mT, and the zero- field-cooled levitation forces of standard samples (38 mm x 38 mm x 12 mm) at 77 K typically are in the range 60-70 N.

Bi Cuprates

A preprint by W. Chen et al. (Alberta) reports the observation of new features in the normal-state resistivity of underdoped Bi2Sr2Ca2Cu3O10+d (Bi-2223) single crystals, in which an upturn deviation from the linear rho vs T, rather than the usual downturn drop, appeared below T* ~ 250 K. The authors suggest that the behavior may result from structural transformations and charge dynamics similar to those in the stripe phases.

As reported by Y. C. Guo (NRIM) et al., the addition of a small amount of SiC (0.15 wt%) to (Bi,Pb)2Sr2Ca2Cu3O10+d [(Bi,Pb)-2223] improves the critical current I_c and its behavior in a magnetic field as a result of enhancements in density, grain alignment, grain connectivity, and flux pinning of the tapes.

The effects of tension rolling of monocore (Bi,Pb)-2223 tapes prepared by the oxide-powder-in-tube method have been studied by H. Utsunomiya et al. (Osaka). The authors found that the optimum tension is ~5 MPa, which suppresses the sausaging of the Ag/oxide interface, improves the oxide grain alignment, and results in higher Jc.

The normal- and superconducting-state c-axis transport properties of Bi2Sr2CaCu2O8+d (Bi-2212) single crystals have been measured by A. Yurgens (Goeteborg) et al. as a function of doping and magnetic fields parallel and perpendicular to the CuO2 planes using mesa structures containing a small number of atomic unit-cell layers. For low current bias, the peak in the magnetic-field-dependent c-axis resistance was found to scale approximately inversely with the zero-field critical current. The critical current I_c was found to depend strongly on the temperature T and the field B_[perp.] perpendicular to the CuO2 planes.

The c-axis I-V characteristics of Bi-2212 show strong hysteresis with many branches. A preprint by H. Matsumoto (Seikei) et al. theoretically studies the origin of hysteresis jumps using a model consisting of a stack of Josephson junctions. Charging effects on the superconducting layers produce a coupling between the phase differences of next-nearest- neighbor junctions, thereby strongly affecting the structure of hysteresis branches.

Other Cuprates

Polarized XAFS measurements by V. Polinger et al. (Washington) on powders of La2-xSrxCuO4 with aligned c axes show that apical oxygens neighboring only the Sr dopants have a double-site distribution. This result requires that the doped holes reside in impurity states peaked on the CuO6 octahedron neighboring the dopant (denoted as Sr-octahedrons). The authors present a model of the double site involving two coexisting spin-differentiated (singlet and triplet) Jahn-Teller distortions of the Sr-octahedrons induced by an extrinsic doped hole pairing with the intrinsic hole. The authors speculate that Bose condensation of the singlet pairs, bound by >=0.1 eV, produces superconductivity.

The ab-plane optical spectra of two single crystals of underdoped La2- xSrxCuO4 have been investigated by T. Startseva (McMaster) et al. The reflectivity of La1.87Sr0.13CuO4 has been measured in the frequency range 30 cm^[-1] - 9000 cm^[-1] (0.004 eV - 1 eV) both parallel and perpendicular to the CuO2 planes, while La1.86Sr0.14CuO4 was studied only in the ab plane. Using the extended Drude model, the authors find that the frequency-dependent effective scattering rate 1/tau(omega,T) is strongly suppressed below the high-frequency straight-line extrapolation, a signature of the pseudogap state. This suppression can be seen from temperatures below the superconducting transition up to 400 K.

Measurements of the temperature (T) dependence of the magnetic penetration depth lambda of grain-aligned YBa2Cu4O8 along the ab plane and the c axis are reported in two preprints by C. Panagopoulos (IRC- Cambridge) et al. Both lambda_[ab](T) and lambda_c(T) vary as T^[1/2] up to ~0.4 Tc, indicating a square-root density of states as predicted, but not previously observed, by the proximity model of alternating stacked superconducting and normal layers. The authors discuss the ab- plane anisotropy and temperature dependence in terms of proximity- induced pair condensation on the chains.

A single crystal of Hg1.44Re0.5Ba4Ca5Cu7O20 [(Hg,Re)-2457, Tc = 83 K] has been grown by H. Schwer et al. (ETH-Zurich) using a gas-phase high- pressure technique at 10 kbar. An x-ray single-crystal structure analysis showed that the crystal is composed of alternating blocks of 1223 and 1234 units. Until now, such intergrowth structures in the Hg- based series have been observed only on a small submicron scale or as a defect.

The preparation of (B1-xCx)(Sr1-yBay)2Ca2Cu3Oz has been studied by A. Iyo and M. Tokumoto (ETL) using high-pressure synthesis techniques to improve sample quality. The authors found a maximum Tc = 120 K for a sample with the starting composition (B0.65C0.35)(Sr0.3Ba0.7)2Ca2Cu3O9+d. From magnetization measurements, the authors estimated the Jc at 77 K in a field of 1 T to be about 1.1 x 10^4 A/cm^2, and H_[irr] at 77 K to be about 2.5 T.

Other Superconductors

As noted in a preprint by C. Bergemann (Cambridge) et al., Sr2RuO4 is the only known layered perovskite oxide superconductor without Cu; there is strong evidence for an unconventional (p-wave) pairing mechanism in this material; and Sr2RuO4 recently has been shown to possess a cylindrical, quasi-two-dimensional Fermi surface. The authors have used a highly sensitive piezolever torque magnetometry technique in a dilution refrigerator to detect quantum magnetization oscillations on all three Fermi surface sheets in a Sr2RuO4 crystal of microgram mass.

A preprint by F. Marsiglio (Alberta) summarizes some well-known properties of the optical reflectance (and the derived conductance), and then demonstrates how a recently derived inversion procedure can be used to infer the magnitude of the electron-phonon interaction from the optical properties. The author applies this procedure to K3C60 and finds that the electron-phonon interaction is sufficiently strong to explain the transition temperature in this material.

A study of the microwave properties of superconducting YNi2B2C and ErNi2B2C has been carried out by A. Andreone (Napoli) et al. The measurements were performed using a microstrip resonator (f = 2 GHz) and a microwave cavity (f = 87 GHz). Analysis of the temperature dependence of the surface impedance Z_s confirms that YNi2B2C is a conventional BCS (s-wave) superconductor, but reveals that ErNi2B2C shows anomalous behavior in both the surface resistance and penetration depth. The authors tentatively ascribe this to pair-breaking effects on the superconducting density of states.

Thin Films

The effects of temporal pulse width and target density on the deposition of thin YBa2Cu3O7-d (YBCO) films has been studied by S. Vikram (Iowa State) et al. A 248 nm excimer laser and an 825 nm Ti-sapphire laser were used to conduct the experiments with pulse widths of 27 ns, 16 ns, and 150 fs and target densities of 80% and 90%. Scanning electron microscope photomicrographs and profilometer traces showed a striking difference between nanosecond and femtosecond laser irradiation. Shortening the pulse width reduced particulate formation, provided stoichiometry, and improved the film properties. Decreasing the target density raised the ablation rate, produced thicker but nonuniform films, and reduced particulate formation.

A preprint by T. Schmauder (Wisconsin and EPFL-Lausanne) et al. describes a new pulsed-laser-deposition system linked to an angle- resolved photoemission (ARPES) chamber at the Synchrotron Radiation Center at the University of Wisconsin. The authors discuss first results on epitaxially grown YBCO films. The core-level photoemission data indicate that a BaO layer is the dominant surface layer. Since the authors were not able to reproducibly detect a sharp Fermi edge in the photoemission spectra, they conclude that the surface layer is nonmetallic, probably due to oxygen loss at the surface.

The magnetic flux distributions in samples consisting of five parallel strips of NdBa2Cu3O7-d (NBCO) thin films arranged in an x-array have been visualized by Z. W. Lin et al. (New South Wales) using a magneto- optical technique. The external magnetic field was applied perpendicular to the sample surface, held at 40 K. The magnetic flux profiles were calculated taking into account the sample thickness and the distance between the sample surface and the indicator film. The experimental results showed excellent agreement with the calculated flux distribution and revealed that for the central strip, flux penetrates deeper into the strip than for a single isolated strip. This is due to field compression resulting from the shielding of the superconducting strips on each side.

Atomic-layer-controlled molecular beam epitaxy (ALC-MBE) has been applied by H. Ota et al. (ETL) for preparing ultrathin films of Bi2Sr2CaCu2O8+d (Bi-2212). Precise control of the composition by ALC- MBE enables the growth of particle-free films. Superconducting zero- resistance transitions were observed for films of thickness greater than 3.0 nm. The authors also found that growth of a Bi2Sr2CuO6 (Bi-2201) buffer layer between the film and the SrTiO3 (100) substrate helps in the preparation of particle-free ultrathin films with good superconducting properties.

Theory

The two-dimensional t-J model has been investigated by C. S. Hellberg (NRL) and E. Manousakis (Florida State) at a hole doping of x = 1/8 and J/t = 0.35 using exact diagonalization. The authors find that the low- energy states are uniform (not striped) but also find numerous excited states with charge-density-wave structures, which may be interpreted as striped phases. Some of these are consistent with neutron scattering data on the cuprates and nickelates.

It is known that in the vicinity of hole density 1/8, the La-based high- Tc superconductors exhibit long-range order of incommensurate antiferromagnetism (IC-AF). Using a Ginzburg-Landau free energy based on a mean-field theory of the t-J model, H. Yamase et al. (Tokyo) have found numerically that three kinds of charge-density modulation (CDM), including a stripe pattern, can stabilize IC-AF ordering.

The dispersion relation of a doped hole in the half-filled 2D Hubbard model has been shown by F. F. Assaad (Stuttgart) and M. Imada (Tokyo) to follow a |k|^4 law around the (0,+-pi) and (+-pi,0) points in the Brillouin zone. Upon addition of pair-hopping processes, this dispersion relation is unstable towards a |k|^2 law. The authors discuss finite dopings and argue that the added term restores coherence to charge dynamics and drives the system towards d_[x^2-y^2] superconductivity.

According to a theory by M. Opel (Walther Meissner Institut, Garching) et al., the buckling of the CuO2 planes in certain cuprate systems can be explained in terms of an electric field across the planes originating from different valences of atoms above and below the plane. The authors find direct experimental support for their ideas in studies of YBa2Cu3O6+x and Bi2Sr2(Ca1-xYx)Cu2O8 with different oxygen and yttrium doping, respectively, including antiferromagnetic samples. In the latter compound, symmetry breaking by replacing Ca partially by Y leads to an enhancement of the electron-phonon coupling by an order of magnitude.

The low-temperature surface resistance R_s of d-wave superconductors has been calculated by C. T. Rieck et al. (Hamburg) as a function of frequency, assuming normal-state quasiparticle mean free paths l in excess of the penetration depth. The size of nonlocal corrections, which can be positive or negative depending on frequency, decreases for given l as the scattering phase shift d_N is increased. However, except in the unitarity limit d_N = pi/2, nonlocal effects should be observable.

A preprint by T. Schneider and J. M. Singer (Zurich) establishes a criterion to test theories for layered superconductors relying on a substantial interlayer contribution. This criterion is based on the ratio of the interlayer contribution to the total superfluid density, which is traced back to the inverse squared effective mass anisotropy. The authors conclude that models relying on interlayer pairing cannot be considered as serious candidates for the mechanism of superconductivity in cuprate superconductors. A second preprint by the same authors discusses the occurrence of crossing points in the magnetization vs temperature (M-T) plane within the framework of critical phenomena.

A preprint by M. C. Bonsager and A. H. MacDonald (Indiana) reports on an exploration of the mean-field phase diagram for Pauli-limited superconductivity in small metallic grains. The authors emphasize the crossover to the bulk thin-film phase diagram as the single-particle level spacing in the grain decreases. They find that the maximum Zeeman coupling strength compatible with superconductivity in small grains exceeds the Clogston paramagnetic limit.

The magnetoresistance of a granular superconductor in a strong magnetic field destroying the gap in each grain is considered in a preprint by I. S. Beloborodov (Bochum) and K. B. Efetov (Bochum and Landau Institute). The authors show that the magnetoresistance of a granular metal in a strong magnetic field at low temperature must be negative because of superconducting fluctuations.

Other Activities

Neutron scattering has been used by H. A. Mook (Oak Ridge) et al. to study the spin fluctuations in YBa2Cu3O7-d and Bi2Sr2CaCu2O8+d. The authors find evidence for both incommensurate fluctuations and a commensurate resonance excitation. Measurements of the lattice dynamics in YBa2Cu3O6.9 show incommensurate structure that appears to stem from charge fluctuations associated with the spin fluctuations.

An angle-resolved photoemission (ARPES) study of insulating Ca2CuO2Cl2, a parent compound of the high-Tc superconductors, has been carried out by F. Ronning (Stanford) et al. Analysis of the electron occupation probability n(k) from the spectra shows a steep drop in spectral intensity across a contour that is close to the Fermi surface predicted by the band calculation, revealing a Fermi-surface remnant even though Ca2CuO2Cl2 is a Mott insulator. Furthermore, the lowest energy peak exhibits a dispersion of approximately the |coskxa - coskya| form along this remnant Fermi surface. As emphasized by the authors, these results, together with the data from Dy-doped Bi2Sr2CaCu2O8+d, suggest that this d-wave-like dispersion of the insulator is the underlying reason for the pseudogap in the underdoped regime.

A model of conduction in polycrystalline high-Tc superconductors, involving weak links at grain boundaries, has been developed by R. Haslinger and R. Joynt (Wisconsin). The model can be reduced to a nonlinear resistor network, which the authors solve by both analytical approximations and a new numerical technique. The authors show that an unambiguous connection can be made between link-strength distributions at the microscopic level and electrical properties at the macroscopic level.

Preprints by S. S. Banerjee (TIFR-Mumbai) et al. and G. Ravikumar (BARC- Mumbai) et al. report on features in the magnetization of 2H-NbSe2, which they associate with an order-disorder transformation across the peak-effect region.

A paper by Y. Bruynseraede and V. V. Moshchalkov (Leuven) reports on flux-confinement effects in superconducting line, loop, and dot structures. The authors note that the critical temperature versus applied field Tc(H) is the energy of the lowest Landau level E_[LLL](H) measured in temperature units, and that E_[LLL](H) is altered when the sample geometry or topology is changed. The authors demonstrate that in all studied submicron structures the shape of the Tc(H) phase boundary is determined by the confinement topology in a unique way.

Overviews

A preprint by M. Darula (Juelich) et al. reviews the status of discrete Josephson-junction arrays for applications as sub-mm wavelength radiation sources. The authors discuss the fundamental aspects of Josephson junctions for oscillator applications and introduce the different possible array types. They also discuss fabrication issues and experimental results on both low-Tc and high-Tc superconductors (144 refs.).

A review summarizing the microstructural variations that result from the addition of Y2BaCuO5 (Y-211) to melt-processed YBa2Cu3O7-d (Y-123) has been prepared by C.-J. Kim and G.-W. Hong (KAERI). The authors discuss the size distribution of Y-211 particles, the microdefects around them, and the effects of chemical doping by PtO2 and CeO2 (115 refs.).

Basic applications of Rutherford backscattering spectrometry (RBS) in cuprate superconductors are reviewed in a preprint by W.-K. Chu et al. (TCSUH). The authors discuss the use of RBS for stoichiometry measurement and for the characterization of films (thickness, elemental depth profiling, interface diffusion, uniformity, radiation damage, crystallinity, and strain measurement). The authors also discuss extensions of this technique to measure thermal-vibration-induced atomic displacements vs temperature, and to study specific oxygen sites via [18]^O labeling (47 refs.).

Ph.D. Thesis

Investigations of the elastic and dissipative forces in superconducting levitation are reported in the Regensburg Ph.D. thesis of R. Grosser, who studied the oscillations of a small permanent magnet levitating between two horizontal superconductors. The author studied the behavior with different samples of YBa2Cu3O7-d, including sintered and melt- textured bulk samples and epitaxial films of thickness 190 nm and 450 nm. Dissipation in the thin-film samples was found to be much smaller than in the bulk samples over nearly the entire temperature range (70 refs.).

Contributed by John R. Clem

Contents: Preprints begin on page 7 and Coming Events begin on page 14.

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.

PREPRINTS To obtain a particular preprint, contact the first author at the address given at the end of the citation. Help us expand this list by sending us your complete preprint. Please specify where and when your paper was submitted. An * next to an entry indicates it is a correction or revision of a previous entry. PACS codes and/or key words are given at the end of the citation.

G. Aldica, P. Badica, and G. Alexe, "Non-Isothermal Pyrolysation of the Spray-Frozen Freeze Dried Complex Nitrate in Bi(Pb)-Sr(Ba)-Ca-Cu-O System Investigated by X-ray Diffraction Analysis." Presented at EPDIC- 6, Budapest, Hungary, Aug. 25-29, 1998; to be published in Mater. Sci. Forum. Contact P. Badica, National Institute of Materials Physics, P.O. Box MG-7, Bucharest-Magurele, R-76900 ROMANIA; telefax +40 1 4231700; e- mail badpet@alpha1.infirm.ro. Key words: x-ray diffraction, non- isothermal pyrolysation, freeze-dried powder, Bi(Pb)-Sr(Ba)-Ca-Cu-O system.

A. Andreone, C. Aruta, M. Iavarone, F. Palomba, M. L. Russo, M. Salluzzo, R. Vaglio, A. Cassinese, M. A. Hein, T. Kaiser, G. Mueller, and M. Perpeet, "Microwave Properties of RE-Ni2B2C (RE=Y,Er) Superconducting Thin Films." To be published in Physica C. INFM- Dipartimento di Scienze Fisiche, Universita di Napoli Federico II, Piazzale Tecchio 80, I-80125 Napoli, ITALY; telephone +39 081 768 2547; telefax +39 081 239 1821; e-mail andreone@na.infn.it or andreone@unina.it. Key words: superconducting borocarbide thin films, surface impedance. 74.72.Ny; 74.76.-w; 74.25.Nf.

F. M. Araujo-Moreira, W. A. Oritz, and O. F. de Lima, "Multilevel Granular Structure and Its Coupling Distribution in Melt-Textured YBa2Cu3O7-d." To be published in Physica C (in press). Contact O. F. de Lima, Instituto de Fisica 'Gleb Wataghin,' Universidade Estadual de Campinas-Unicamp, 13083-970 Campinas, SP, BRAZIL; telephone +55 19 788- 5504 or -5460; telefax +55 19 289-3137; e-mail delima@ifi.unicamp.br. Key words: ac susceptibility, critical current density, granular superconductivity, couplings distribution.

F. F. Assaad and M. Imada, "Hole Dynamics in Two-Dimensional Antiferromagnetic Mott Insulators." Institut fuer Theoretische Physik III, Universitaet Stuttgart, Pfaffenwaldring 57, D-70550 Stuttgart, GERMANY; e-mail assaad@theo3.physik.uni-stuttgart.de; preprint also available at cond-mat@xxx.lanl.gov (#9811384). 71.27.+a; 71.30.+h; 71.10.+x.

D. K. Aswal, M. Shinmura, Y. Hayakawa, and M. Kumagawa, "Effects of Solute-to-Solvent Ratio and Cooling Rate on the Nucleation Temperature of NdBa2Cu3Ox." To be published Advances in Supercond. XI: Proc. of the 11th Int. Symp. on Superconductivity (ISS'98), Fukuoka, Japan, Nov. 16-19, 1998; edited by N. Koshizuka and S. Tajima (Springer-Verlag, Tokyo). Research Institute of Electronics, Shizuoka University, 3-5-1 Johoku, Hamamatsu 432-8011, JAPAN; telephone +81 53 478 1338; telefax +81 53 478 1338; e-mail roaswal@eng.shizuoka.ac.jp. Key words: nucleation temperature, high-temperature optical microscopy, NdBa2Cu3Ox.

P. Badica, G. Aldica, and S. Mandache, "One Step Synthesis of Bi(Pb)- 2223 Phase in Bi(Pb)-Sr(Ba)-Ca-Cu-Nitrate Freeze Dried Powder." To be published in Supercond. Sci. & Technol. National Institute of Materials Physics, P.O. Box MG-7, Bucharest-Magurele, R-76900 ROMANIA; telefax +40 1 4231700; e-mail badpet@alpha1.infirm.ro.

U. Balachandran, M. Lelovic, N. G. Eror, J. Talvacchio, R. Young, V. Selvamanickam, and P. Haldar, "Enhancement of Critical Currents in (Bi,Pb)2Sr2Ca2Cu3Oy (Bi-2223) Superconducting Tapes." Submitted to Advances in Supercond. XI: Proc. of the 11th Int. Symp. on Superconductivity (ISS'98), Fukuoka, Japan, Nov. 16-19, 1998; edited by N. Koshizuka and S. Tajima (Springer-Verlag, Tokyo). Contact Janice Coble, Materials Science Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439; telephone (630) 252-5497; telefax (630) 252-9595; e-mail coble@anl.gov. Key words: powder-in-tube (PIT) technique, Bi-2223 superconducting tapes, Y-123 thin film, magnetic shielding.

S. S. Banerjee, S. Ramakrishnan, A. K. Grover, G. Ravikumar, P. K. Mishra, V. C. Sahni, P. L. Gammel, D. J. Bishop, E. Bucher, M. J. Higgins, and S. Bhattacharya, "Simultaneous Occurence of Fishtail Effect and Peak Effect in 2H-NbSe2." Preprint #TIFR/CM/98/203(II); submitted to Phys. Rev. Lett. Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400005, INDIA; e-mail sb@tifr.res.in; A. K. Grover's telephone +91 22 215-2971 or -2979; telefax +91 22 215-2181 or -2110; e-mail grover@tifr.res.in. Key words: fishtail effect, peak effect, order-disorder phase boundary, reentrance, 2H-NbSe2. 64.70.Dv; 74.60.Ge; 74.25.Dw; 74.60.Ec; 74.60.Jg.

D. Belitz and T. R. Kirkpatrick, "Properties of Spin-Triplet, Even- Parity Superconductors." Preprint #DB/97/04. Department of Physics and Materials Science Institute, University of Oregon, Eugene, OR 97403; e- mail belitz@greatwhite.uoregon.edu; preprint also available at cond- mat@xxx.lanl.gov (#9812130).

I. S. Beloborodov and K. B. Efetov, "Negative Magnetoresistance of Granular Metals in a Strong Magnetic Field." Theoretische Physik III, Ruhr-Universitaet Bochum, D-44780 Bochum, GERMANY; e-mail igorb@tp3.ruhr-uni-bochum.de; preprint also available at cond- mat@xxx.lanl.gov (#9811173). 73.23.-b; 74.80.Bj; 74.40.+k; 72.15.Rn.

C. Bergemann, S. R. Julian, A. P. Mackenzie, A. W. Tyler, D. E. Farrell, Y. Maeno, and S. NishiZaki, "Quantum Oscillations and Overcritical Torque Interaction in Sr2RuO4." Low Temperature Physics Group, Cavendish Laboratory, University of Cambridge, Madingley Road, Cambridge CB3 0HE, UNITED KINGDOM; telephone +44 1223 337422; telefax +44 1223 363263; e-mail cb203@cus.cam.ac.uk; preprint also available at cond- mat@xxx.lanl.gov (#9811364).

C. Bernhard, D. Munzar, M. Klaeser, Th. Wolf, C. T. Lin, and M. Cardona, "The Electronic c-Axis Conductivity of Y1-xCaxBa2Cu3O7-d Single Crystals Studied by Far-Infrared Ellipsometry." To be published in Physica C: Proc. of the First Crete Euroconference on Anomalous Complex Superconductors (ACS-1), Heraklion, Greece, Sept. 25-Oct. 2, 1998. Max- Planck-Institut fuer Festkoerperforschung, Heisenbergstrasse 1, D-70569 Stuttgart, GERMANY; telephone +49 711 689 1733; telefax +49 711 689 1010; e-mail bernhard@cardix.mpi-stuttgart.mpg.de. 78.30.-j; 74.25.Gz; 78.20.Ci; 74.72.Bk.

M. C. Bonsager and A. H. MacDonald, "Pauli-Limited Superconductivity in Ultra-Small Grains: Beating the Clogston Limit." Department of Physics, Swain Hall West 117, Indiana University, Bloomington, IN 47405; e-mail bonsager@gibbs.physics.indiana.edu; preprint also available at cond-mat@xxx.lanl.gov (#9812042).

E. Bruneel and S. Hoste, "Screening Properties and Critical Current of Superconductor-MgO Composites." Submitted to J. Inorganic Mater. Department of Inorganic and Physical Chemistry, Solid State and Superconducting Materials Division, University of Gent, Krijgslaan 281, B-9000 Gent, BELGIUM; telephone +32 9 264 4440; telefax +32 9 264 4983; e-mail els.bruneel@rug.ac.be. Key words: HTSC, composites, ac susceptibility, percolation.

Y. Bruynseraede and V. V. Moshchalkov, "Flux Confinement in Mesoscopic Superconductors." Submitted to J. Superlatt. and Microstruc. Laboratorium voor Vaste Stoffysica en Magnetisme, Katholieke Universiteit Leuven, Celestijnenlaan 200 D, B-3001 Leuven, BELGIUM; V. V. Moshchalkov's telephone +32 16 32 7618; telefax +32 16 32 7983; e- mail victor.moshchalkov@fys.kuleuven.ac.be.

Sujeet Chaudhary, S. B. Roy, and P. Chaddah, "Orientation-Induced Crossover in Pinning Force Density and Peak Effect in Bi2Sr2CaCu2O8+x Single Crystal." To be published in Physica C (in press). Low Temperature Physics Group, Centre for Advanced Technology, Indore 452 013, INDIA; telefax +91 731 488300; e-mail sujeetc@cat.ernet.in. Key words: superconductors, Bi-2212 single crystal, pinning force density.

H. S. Chauhan and M. Murakami, "On Improving Irreversibility Field in Nd422 Rich Nd123 Systems with a Modified Growth Technique." To be published in Advances in Supercond. XI: Proc. of the 11th Int. Symp. on Superconductivity (ISS'98), Fukuoka, Japan, Nov. 16-19, 1998; edited by N. Koshizuka and S. Tajima (Springer-Verlag, Tokyo). Superconductivity Research Laboratory, International Superconductivity Technology Center (ISTEC), 3-35-2 Iioka-Shinden, Morioka, Iwate 020-0852, JAPAN; e-mail chauhan@istec.or.jp. Key words: Nd-Ba-Cu-O, OCMG, irreversibility field, double-step temperature growth.

Weimin Chen, J. P. Franck, and J. Jung, "Unusual Features in the Normal State Resistivity of Bi-2223 Whiskers." Submitted to Phys. Rev. B. Department of Physics, University of Alberta, Edmonton, Alberta, CANADA T6G 2J1. 74.25.Fy; 74.72.Hs.

May Chiao, R. W. Hill, Christian Lupien, Bojana Popic, Robert Gagnon, and Louis Taillefer, "Quasiparticle Transport in the Vortex State of YBa2Cu3O6.9." Canadian Institute for Advanced Research and Department of Physics, McGill University, Montreal, Quebec, CANADA H3A 2T8; telephone (416) 978-1507; telefax (416) 978-5848; e-mail may@physics.utoronto.ca. 74.70.Tx; 74.25.Fy.

W. K. Chu, J. R. Liu, and Z. H. Zhang, "Application of Rutherford Backscattering Spectrometry to Cuprate Superconductors." Preprint #98:139; submitted to the Proc. of the 215th Nat. Amer. Chem. Soc. Mtg., Dallas, Texas, March 29-April 3, 1998. 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.

M. Darula, T. Doderer, and S. Beuven, "mm and Sub-mm Wavelength Radiation Sources Based on Discrete Josephson Junction Arrays." To be published in Supercond. Sci. & Technol. Institut fuer Schicht- und Ionentechnik, Forschungszentrum Juelich GmbH, D-52425 Juelich, GERMANY; T. Doderer's telephone at IBM T. J. Watson Research Center, NY (914) 945-4201; telefax (914) 945-2141; e-mail doderer@watson.ibm.com. 74.50.+r; 85.25.Cp; 07.57.Hm.

J. Demsar, B. Podobnik, J. E. Evetts, G. A. Wagner, and D. Mihailovic, "Evidence for Crossover from a Bose-Einstein Condensate to a BCS-Like Superconductor with Doping in YBa2Cu3O7-d from Quasiparticle Relaxation Dynamics Experiments." To be published in Europhys. Lett. Contact D. Mihailovic, Solid State Physics Department, Jozef Stefan Institute, Jamova 39, 1001 Ljubljana, SLOVENIA; telephone +386 61 1773 729; telefax +386 61 1251 077; e-mail dragan.mihailovic@ijs.si; preprint also available at cond-mat@xxx.lanl.gov (#9812079). 74.25.Dw; 74.25.Jb; 78.47.+p.

S. Dorbolo, M. Ausloos, H. Bougrine, B. Robertz, R. Cloots, J. Mucha, and K. Durczewski, "Effect of Synthesis Process and Substrate on Electrical and Thermal Transport Properties of Bi-2212." To be published in J. Supercond. SUPRAS, Institute of Physics B5, University of Liege, B-4000 Liege, BELGIUM; e-mail s.dorbolo@ulg.ac.be.

Xiao-Juan Fan, Gang Ji, and Xiao-Guang Li, "The Effect of the Superconducting-Normal Proximity on the Josephson Tunneling of High-Tc Superconductors." To be published in Physica C (in press). Department of Materials Science and Engineering, University of Science and Technology of China, Heifei 230026, PEOPLE'S REPUBLIC OF CHINA. Key words: superconducting-normal bilayer model, Josephson tunneling, high- Tc superconductor.

I. A. Fradina, A. F. Alekseev, T. Ja. Gridasova, V. V. Morozov, and D. O. Jurchenko, "Influence of Pelletization Pressure on Magnetic Susceptibility Samples of Ceramics Bi(Pb)-Sr-Ca-Cu-O." To be published in Physica C (in press). Department of High-Temperature Materials and Powder Metallurgy, National Technical University of Ukraine (Kiev Polytechnical Institute), 252056 Kiev, UKRAINE; telephone +380 44 516 5513; telefax +380 44 241 7611; e-mail bogast@chem.ntu-kpi.kiev.ua. Key words: magnetic susceptibility, scanning electron microscopy, grain borders.

T. L. Francavilla, H. R. Khan, and V. M. Browning, "The Magnetic Field and Temperature Dependent Transport Critical Current Density of Hg-Pb- Bi-Ca-Cu-O Ceramic Compounds." To be published in IEEE Trans. Appl. Supercond.: Proc. of the 1998 Appl. Supercond. Conf. (ASC), Palm Desert, Calif., Sept. 13-18, 1998. Code 6344, Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, DC 20375-5343.

Ryoji Funahashi, Ichiro Matsubara, Kazuo Ueno, and Hiroshi Ishikawa, "Mechanism of Bi2Sr2CaCu2Ox Crystallization and Superconducting Properties for Bi2Sr2CaCu2Ox/Ag Tapes Prepared Using Isothermal Partial Melting Method." To be published in Physica C (in press). Osaka National Research Institute, AIST, Midorigaoka, Ikeda, Osaka 563, JAPAN; telephone +81 727 51 9541; telefax +81 727 51 9622; e-mail fune@onri.go.jp. Key words: Bi2Sr2CaCu2Ox/Ag tapes, isothermal partial-melting method, crystallization mechanism, peritectic reaction.

B. R. Gadjiev and N. A. Javadov, "Nonlinear Phonons in High-Tc Superconductor Mixed Crystals." Preprint #P17-98-128. Joint Institute for Nuclear Research, 141980 Dubna, Moscow Region, RUSSIA. (Preprint in Russian.)

K. Gorny, O. M. Vyaselev, J. A. Martindale, V. A. Nandor, C. H. Pennington, P. C. Hammel, W. L. Hults, J. L. Smith, P. L. Kuhns, A. P. Reyes, and W. G. Moulton, "Magnetic Field Independence of the Spin Gap in YBa2Cu3O7-d." Preprint #LA-UR-98-4640; to be published in Phys. Rev. Lett. Department of Physics, Ohio State University, 174 W. 18th Avenue, Columbus, OH 43210; P. C. Hammel's telephone at Los Alamos National Laboratory, NM (505) 665-0759; telefax (505) 665-7652; e-mail pch@lanl.gov; preprint also available at cond-mat@xxx.lanl.gov (#9812013). 74.25.Nf; 74.72.Bk; 76.60.Es; 74.20.Mn.

Tomoko Goto, Takehiro Shimizu, and Kazuo Watanabe, "Critical Current Density of Both F and Cl Doped Filamentary Hg1223 Superconductors." To be published in IEEE Trans. Appl. Supercond. Department of Materials Science and Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466, JAPAN; telephone +81 52 735 5265; telefax +81 52 735 5294; e-mail zwgoto@mse.nitech.ac.jp.

Hermann Grabert and Gert-Ludwig Ingold, "Mesoscopic Josephson Effect." Submitted to Superlatt. and Microstruc. Fakultaet fuer Physik, Albert- Ludwigs-Universitaet, Hermann-Herder-Strasse 3, D-79104 Freiburg, GERMANY; Gert-Ludwig Ingold's e-mail at Universitaet Augsburg, gert.ingold@physik.uni-augsburg.de; preprint also available at cond- mat@xxx.lanl.gov (#9811194).

F. M. Grosche, P. Agarwal, S. R. Julian, N. J. Wilson, R.K.W. Haselwimmer, S.J.S. Lister, N. D. Mathur, F. V. Carter, S. S. Saxena, and G. G. Lonzarich, "Anomalous Low Temperature States in CeNi2Ge2." Max-Planck-Institute for Physics of Complex Systems, Bayreuther Str. 40, D-01187 Dresden, GERMANY; e-mail grosche@cpfs.mpg.de; preprint also available at cond-mat@xxx.lanl.gov (#9812133). 74.20.Mn; 71.27.+a.

Reiner Grosser, "Elastic and Dissipative Forces in Superconducting Levitation." Submitted as a Ph.D. thesis (Universitaet Regensburg). Contact Michael Niemetz, Institut fuer Experimentelle und Angewandte Physik, Universitaet Regensburg, D-93051 Regensburg, GERMANY; e-mail michael.niemetz@physik.uni-regensburg.de. (Thesis in German.)

Y. C. Guo, Y. Tanaka, T. Kuroda, S. X. Dou, and Z. Q. Yang, "Addition of Nanometer SiC in the Silver-Sheathed Bi2223 Superconducting Tapes." To be published in Physica C (in press). First Research Group, National Research Institute for Metals, 1-2-1 Sengen, Tsukuba, Ibaraki 305, JAPAN; telephone +81 298 59 2311; telefax +81 298 59 2301; e-mail ycguo@nrim.go.jp. Key words: (Bi,Pb)2Sr2Ca2Cu3O10, nanometer SiC, critical current, grain alignment, flux pinning.

G. C. Han and C. K. Ong, "Low-Field Irreversibility Line and Its Anisotropy of Textured (Bi,Pb)2Sr2Ca2Cu3Oy Silver-Clad Tapes." To be published in Physica C (in press). Department of Physics, National University of Singapore, 10 Lower Kent Ridge, 119260 SINGAPORE; telephone +65 772 2816; telefax +65 778 2968; e-mail phyhangc@leonis.nus.edu.sg. Key words: irreversibility line, vortex motion, high-temperature superconductors. 74.60.Ge; 74.72.Hs; 74.60.Jg.

Robert Haslinger and Robert Joynt, "Theory of Percolative Conduction in Polycrystalline High-Temperature Superconductors." Department of Physics and Applied Superconductivity Center, University of Wisconsin- Madison, 1150 University Avenue, Madison, WI 53706; e-mail haslinger@landau.physics.wisc.edu; preprint also available at cond- mat@xxx.lanl.gov (#9811255). 95.30.Cq; 97.10.Cv; 97.60.Jd.

C. Stephen Hellberg and E. Manousakis, "Stripes and the t-J Model." Complex Systems Theory Branch, Naval Research Laboratory, Washington, DC 20375; e-mail hellberg@dave.nrl.navy.mil; preprint also available at cond-mat@xxx.lanl.gov (#9812022). 71.10.Fd; 74.20.Mn; 71.10.Pm.

T. Higuchi, S. I. Yoo, and M. Murakami, "Comparative Study of Critical Current Densities and Flux Pinning Among a Flux-Grown Nd123 Single Crystal, Melt-Textured Nd-Ba-Cu-O, and Y-Ba-Cu-O Bulks." To be published in Phys. Rev. B. Materials Engineering Laboratory, Railway Technical Research Institute, 2-8-38 Hikari-cho, Kokubunji-shi, Tokyo 185-8540, JAPAN; telephone +81 42 573 7297; telefax +81 42 573 7360; e- mail tenko@rtri.or.jp. Key words: Nd-Ba-Cu-O, Y-Ba-Cu-O, critical current density, vortex pinning, peak effect, phase diagram.

F. Hillmer, G. Jakob, P. Haibach, U. Frey, Th. Kluge, H. Adrian, G. Wirth, E. Jaeger, and E. Schimpf, "Absence of Correlated Flux Pinning by Columnar Defects in Irradiated Epitaxial Bi2Sr2CaCu2O8 Thin Films." To be published in Physica C (in press). Institut fuer Physik, Johannes Gutenberg-Universitaet Mainz, D-55099 Mainz, GERMANY; telephone +49 6131 39 3631; telefax +49 6131 39 5156; e-mail hillmer@mail.uni-mainz.de. Key words: critical current density, flux pinning, irradiation effect, thin films. 74.60.Ge; 74.60.Jg; 74.72.Hs.

R. P. Huebener, O. M. Stoll, and S. Kaiser, "Electronic Vortex Structure and Quasiparticle Scattering in the Cuprate Superconductor Nd2- xCexCuOy." To be published in Phys. Rev. Physikalisches Institut, Lehrstuhl Experimentalphysik II, Universitaet Tuebingen, Morgenstelle 14, D-72076 Tuebingen, GERMANY. 74.25.Fy; 74.60.Ge; 74.72.Jt.

A. Iyo and M. Tokumoto, "Preparation and Superconductivity of (B1- xCx)(Sr1-yBay)2Ca2Cu3Oz." To be published in Physica C (in press). Electrotechnical Laboratory, 1-1-4 Umezono, Tsukuba, Ibaraki 305, JAPAN; telephone +81 298 54 5435; telefax +81 298 54 5447; e-mail iyo@etl.go.jp. Key words: high-pressure synthesis, (B1-xCx)(Sr1- yBay)2Ca2Cu3Oz, substitution effect, critical current density, irreversibility field. 74.62.Bf; 74.62.-c; 74.60.Jg.

Goeran Johansson, Goeran Wendin, Kateryna N. Bratus, and Vitaly S. Shumeiko, "Multiple Andreev Reflections as a Transport Problem in Energy Space." To be published in Superlatt. and Microstruc. Chalmers University of Technology and Goeteborg University, S-41296 Goeteborg, SWEDEN; e-mail tfygj@fy.chalmers.se; preprint also available at cond- mat@xxx.lanl.gov (#9811195).

Amish G. Joshi, M. V. Subbarao, Nikesh A. Shah, D. G. Kuberkar, and R. G. Kulkarni, "Effect of Mo and Mo-Ca Substitution on the Superconductivity of GdBa2Cu3O7-d." To be published in Appl. Supercond. Department of Physics, Saurashtra University, Rajkot 360 005, INDIA; telephone +91 2817 8505; telefax +91 2817 7885.

S. Kashiwaya, Y. Tanaka, N. Yoshida, and M. R. Beasley, "Spin Current in Ferromagnet/Insulator/Superconductor Junctions." Submitted to Phys. Rev. Lett. Ginzton Laboratory, Box GL-N149, Stanford University, Stanford, CA 94305-4085; telephone (650) 723-1945; telefax (650) 725- 2189; e-mail satoshik@loki.stanford.edu; preprint also available at cond-mat@xxx.lanl.gov (#9812160). 74.50.+r; 74.72.-h; 74.80.Fp.

Chan-Joong Kim and Gye-Won Hong, "Defect Formation, Distribution, and Size Reduction of Y2BaCuO5 in Melt-Processed YBCO Superconductors." To be published in Supercond. Sci. & Technol. Superconductivity Research Laboratory, Korea Atomic Energy Research Institute, P.O. Box 105, Yusung, Taejon 305-600, SOUTH KOREA; telephone +82 42 868 8908; telefax +82 42 862 5496; e-mail cjkim2@nanum.kaeri.re.kr.

Takuji Kimura, Tomoko Goto, and Kazuo Watanabe, "Critical Current Density of Filamentary Nd123 Superconductor by Solution Spinning Method." Submitted to IEEE Trans. Appl. Supercond. Department of Materials Science and Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466, JAPAN; Tomoko Goto's telephone +81 52 735 5265; telefax +81 52 735 5294; e-mail zwgoto@mse.nitech.ac.jp.

M. R. Koblischka, T. Higuchi, S. I. Yoo, and M. Murakami, "Scaling of Pinning Forces in NdBa2Cu3O7-d Superconductors." To be published in J. Appl. Phys. Superconductivity Research Laboratory, International Superconductivity Technology Center (ISTEC), 1-16-25 Shibaura, Minato- ku, Tokyo 105, JAPAN; telephone +81 3 3454 9284; telefax +81 3 3454 9287; e-mail koblischka@istec.or.jp. 74.60.Ec; 74.60.Ge; 74.60.Jg.

Z. W. Lin, J. W. Cochrane, N. E. Lumpkin, and G. J. Russell, "Magneto- Optical Observations of Magnetic Flux Distribution in a HTSC X-Array." To be published in Physica C. Advanced Electronic Materials Group, School of Physics, University of New South Wales, Sydney NSW 2052, AUSTRALIA; e-mail lzw@newt.phys.unsw.edu.au.

Tomas Loefwander, Goeran Johansson, Vitaly Shumeiko, Goeran Wendin, and Magnus Hurd, "Resonant Transport Through Midgap States in Voltage-Biased Josephson Junctions of d-Wave Superconductors." Submitted to a special volume of Superlatt. and Microstruc. Chalmers University of Technology and Goeteborg University, S-41296 Goeteborg, SWEDEN; e-mail tfstomas@fy.chalmers.se; preprint also available at cond- mat@xxx.lanl.gov (#9811302).

N. I. Lundin, L. Y. Gorelik, R. I. Shekhter, M. Jonson, and V. S. Shumeiko, "Mesoscopic Superconductors under Irradiation: Microwave Spectroscopy of Andreev States." To be published in Superlatt. and Microstruc. Condensed Matter Theory Group, Department of Applied Physics, Chalmers University of Technology and Goeteborg University, S- 41296 Goeteborg, SWEDEN; telephone +46 31 772 3186; telefax +46 31 41 6984; e-mail nlundin@fy.chalmers.se; preprint also available at cond- mat@xxx.lanl.gov (#9811200).

F. Marsiglio, "Inversion of Optical Reflectance in the Fullerenes." Presented at Quantum Coherence in Supercond. and Nanostruc. -- XXII Int. School of Theoretical Physics, Ustron, Poland, Sept. 10-15, 1998. Department of Physics, University of Alberta, Edmonton, Alberta, CANADA T6G 2J1; e-mail fmars@phys.ualberta.ca.

A. Martin-Rodero, A. Levy Yeyati, and J. C. Cuevas, "General Transport Properties of Superconducting Quantum Point Contacts: A Green's Function Approach." Submitted to a special volume of Superlatt. and Microstruc. Departamento de Fisica Teorica de la Materia Condensada C- V, Universidad Autonoma de Madrid, E-28049 Madrid, SPAIN; A. Levy Yeyati's e-mail aly@uamc11.fmc.uam.es; preprint also available at cond- mat@xxx.lanl.gov (#9811290).

M. Matlak and M. Pietruszka, "Reentrant and Nonreentrant Properties of Magnetic Superconductors: Critical Electron Redistribution." To be published in Physica C (in press). Institute of Physics, University of Silesia, 4 Uniwersytecka, PL-40-007 Katowice, POLAND; e-mail pietruma@usctoux1.cto.us.edu.pl. Key words: magnetic superconductor, critical electron distribution, critical temperature.

Hideki Matsumoto, Shoichi Sakamoto, Fumihiro Wajima, Tomio Koyama, and Masahiko Machida, "Simulation of I-V Hysteresis Branches in an Intrinsic Stack of Josephson Junctions in High-Tc Superconductors." Department of Applied Physics, Seikei University, Kichijoji Kitamachi 3-3-1, Musashino-Shi, Tokyo 180, JAPAN; e-mail matumoto@apm.seikei.ac.jp.

L. V. Mercaldo, Steven M. Anlage, and L. Maritato, "Microwave Surface Impedance of Proximity-Coupled Superconducting (Nb)/Spin-Glass (CuMn) Bilayers." To be published in Phys. Rev. B. Center for Superconductivity Research, Department of Physics, University of Maryland, College Park, MD 20742-4111; telephone (301) 405-7670; telefax (301) 405-3779; e-mail luciam@squid.umd.edu; preprint also available at cond-mat@xxx.lanl.gov (#9811347). Key words: proximity-effect, superconductivity and magnetism, microwave properties, penetration depth, surface resistance. 74.80.Dm; 74.50.+r; 74.25.Nf.

D. Mihailovic, J. Demsar, and B. Podobnik, "Evolution of the Gap Structure from Underdoped to Optimally Doped YBa2Cu3O7-d from Femtosecond Optical Spectroscopy." To be published in J. Supercond.: Proc. of the Int. Conf. on Stripes, Lattice Instabilities, and High Tc Supercond., Rome, Italy, June 2-7, 1998. Solid State Physics Department, Jozef Stefan Institute, Jamova 39, 1001 Ljubljana, SLOVENIA; telephone +386 61 1773 729; telefax +386 61 1251 077; e-mail dragan.mihailovic@ijs.si. Key words: quasiparticle dynamics, phase separation, energy gap, optical studies.

D. Mihailovic, J. Demsar, B. Podobnik, V. V. Kabanov, J. E. Evetts, G. A. Wagner, and L. Mechin, "Quasiparticle Dynamics from the Bose-Einstein Condensation to the BCS-Like Regions of the Phase Diagram in YBa2Cu3O7- d." Submitted to the Proc. of the Euroconf. on Polarons: Condensation, Pairing, Magnetism, Erice, Italy, June 9-17, 1998; to be published in J. Supercond. Solid State Physics Department, Jozef Stefan Institute, Jamova 39, 1001 Ljubljana, SLOVENIA; telephone +386 61 1773 729; telefax +386 61 1251 077; e-mail dragan.mihailovic@ijs.si.

H. A. Mook, F. Dogan, and B. C. Chakoumakos, "Magnetic and Charge Fluctuations in High-Tc Superconductors." To be published in the Proc. of the Int. Conf. on Stripes, Lattice Instabilities, and High Tc Supercond., Rome, Italy, June 2-7, 1998. Oak Ridge National Laboratory, Oak Ridge, TN 37831-6393; preprint also available at cond- mat@xxx.lanl.gov (#9811100). 74.72.Bk; 61.12.Ex.

M. A. Moore and A. Perez-Garrido, "Absence of a Finite-Temperature Melting Transition in the Classical Two-Dimensional One-Component Plasma." Theoretical Physics Group, Department of Physics and Astronomy, University of Manchester, Manchester, M13 9PL, UNITED KINGDOM; A. Perez-Garrido's e-mail in Murcia, Spain jotoni@fcu.um.es; preprint also available at cond-mat@xxx.lanl.gov (#9812039). 64.70.-p; 74.60.-w.

N. Morozov, L. N. Bulaevskii, M. P. Maley, J. Y. Coulter, A. E. Koshelev, and T.-W. Li, "Angular Dependence of c-Axis Magnetoresistance in Bi2Sr2CaCu2O8+d Single Crystals with Columnar Defects." Submitted to Phys. Rev. B. MS-K763, Superconductivity Technology Center, Los Alamos National Laboratory, K763, Los Alamos, NM 87545; e-mail morozov@lanl.gov; preprint also available at cond-mat@xxx.lanl.gov (#9812015). 74.60.Ge; 74.25.Fy; 74.62.Dh.

Andrei Mourachkine, "The Magnetic Origin in d_[x^2-y^2] High-Tc Superconductivity from Tunneling Spectroscopy Measurements on Bi2Sr2CaCu2O8+x Single Crystals." Submitted to Eur. Phys. J. B. Service Physique des Solides, Universite Libre de Bruxelles, CP233, Boulevard du Triomphe, B-1050 Brussels, BELGIUM; telephone +32 2 650 5758; telefax +32 2 650 5916; e-mail anmourac@ulb.ac.be; preprint also available at cond-mat@xxx.lanl.gov (#9811284). 74.20.Mn; 74.50.+r; 74.72.Hs.

Miryala Muralidhar, Kouichi Kamada, Takashi Saitoh, Koji Segawa, Michael Rudolf Koblischka, and Masato Murakami, "Effect of Pt Addition on Microstructure and Magnetic Properties in OCMG-Processed (Nd,Eu,Gd)-Ba- Cu-O." Submitted to Advances in Supercond. XI: Proc. of the 11th Int. Symp. on Superconductivity (ISS'98), Fukuoka, Japan, Nov. 16-19, 1998; edited by N. Koshizuka and S. Tajima (Springer-Verlag, Tokyo). Superconductivity Research Laboratory, International Superconductivity Technology Center (ISTEC), 3-35-2 Iioka-Shinden, Morioka, Iwate 020- 0852, JAPAN; telephone +81 19 635-9015 or -9016; telefax +81 19 635- 9017; e-mail miryala@istec.or.jp. Key words: OCMG process, NEG123, NEG211, Pt addition, high Jc.

M. Muralidhar, M. R. Koblischka, and M. Murakami, "Effect of Platinum Addition on the Microstructure and Critical Current Density in (Nd,Eu,Gd)-Ba-Cu-O." To be published in Supercond. Sci. and Technol. Superconductivity Research Laboratory, International Superconductivity Technology Center (ISTEC), 3-35-2 Iioka-Shinden, Morioka, Iwate 020- 0852, JAPAN; telephone +81 19 635-9015 or -9016; telefax +81 19 635- 9017; e-mail miryala@istec.or.jp. Key words: melt processing, (Nd,Eu,Gd)Ba2Cu3Oy, Gd2BaCuO5, Pt addition, flux pinning, critical current density. 74.60.Ge; 74.60.Jg; 74.80.Bj.

Yoshihiko Nonomura, Xiao Hu, and Masashi Tachiki, "Flux-Line Entanglement as the Mechanism of Melting Transition in High-Temperature Superconductors in a Magnetic Field." National Research Institute for Metals, 1-2-1 Sengen, Tsukuba-shi, Ibaraki 305 0047, JAPAN; e-mail nono@nrim.go.jp; preprint also available at cond-mat@xxx.lanl.gov (#9812002). 74.60.Ge; 74.25.Dw; 74.20.De; 74.25.Bt.

Peter Olsson and S. Teitel, "Correlation Lengths in the Vortex Line Liquid of a High-Tc Superconductor." Department of Theoretical Physics, Umea University, S-901 87 Umea, SWEDEN; S. Teitel's e-mail in Rochester, N.Y., stte@pas.rochester.edu; preprint also available at cond- mat@xxx.lanl.gov (#9810169). 64.60.-i; 74.60.-w; 74.76.-w.

M. Opel, R. Hackl, T. P. Devereaux, A. Virosztek, A. Zawadowski, A. Erb, E. Walker, H. Berger, and L. Forro, "Physical Origin of the Buckling in CuO2: Electron-Phonon Coupling and Raman Spectra." Walther Meissner Institut fuer Tieftemperaturforschung, D-85748 Garching, GERMANY; T. P. Devereaux's e-mail at George Washington University, Washington, DC tpd@gwis2.circ.gwu.edu. 74.72.-h; 63.20.Kr; 78.20.Bh; 71.10.-w.

H. Ota, S. Migita, Y. Kasai, H. Matsuhata, and S. Sakai, "Particle-Free Superconducting Bi2Sr2CaCu2Ox Ultrathin Films Prepared by Atomic-Layer- Controlled Molecular Beam Epitaxy Technique." To be published in Physica C (in press). Contact S. Sakai, Electrotechnical Laboratory, 1- 1-4 Umezono, Tsukuba, Ibaraki 305-8568, JAPAN; telefax +81 298 54 5476; e-mail ssakai@etl.go.jp. Key words: Bi-based cuprates, BSCCO, ultrathin films, molecular beam epitaxy, atomic-layer-controlled growth. 74.76.Bz; 74.72.-h; 74.72.Hs; 81.15.Hi.

Christos Panagopoulos, Jeffrey L. Tallon, and Tao Xiang, "Effects of the Cu-O Chains on the Anisotropic Penetration Depth of YBa2Cu4O8." Submitted to Phys. Rev. Interdisciplinary Research Centre in Superconductivity, University of Cambridge, Madingley Road, Cambridge CB3 0HE, UNITED KINGDOM; telephone +44 1223 337-072 or -076; telefax +44 1223 337-074; e-mail cp200@hermes.cam.ac.uk; preprint also available at cond-mat@xxx.lanl.gov (#9812333). 74.25.Nf; 74.50.+r; 74.72.Bk.

C. Panagopoulos, T. Xiang, J. R. Cooper, and J. L. Tallon, "Low Temperature Penetration Depth Measurements in High-Tc Superconductors." To be published in Advances in Supercond. XI: Proc. of the 11th Int. Symp. on Superconductivity (ISS'98), Fukuoka, Japan, Nov. 16-19, 1998; edited by N. Koshizuka and S. Tajima (Springer-Verlag, Tokyo). Interdisciplinary Research Centre in Superconductivity, University of Cambridge, Madingley Road, Cambridge CB3 0HE, UNITED KINGDOM; telephone +44 1223 337-072 or -076; telefax +44 1223 337-074; e-mail cp200@hermes.cam.ac.uk. Key words: superfluid density, energy gap, c- axis coupling.

Victor Polinger, Daniel Haskel, and Edward A. Stern, "Jahn-Teller Impurity States in LaSrCuO: XAFS Evidence and Implications for High Tc Superconductivity." Submitted to Phys. Rev. Lett. Department of Physics, Box 351560, University of Washington, Seattle, WA 98195; Daniel Haskel's telephone (206) 543-0435; telefax (206) 685-0635; e-mail haskel@dirac.phys.washington.edu; preprint also available at cond- mat@xxx.lanl.gov (#9811425).

G. Ravikumar, P. K. Mishra, V. C. Sahni, S. S. Banerjee, S. Ramakrishnan, A. K. Grover, P. L. Gammel, D. J. Bishop, E. Bucher, M. J. Higgins, and S. Bhattacharya, "Step Change in Equilibrium Magnetization Across the Peak Effect in 2H-NbSe2." Submitted to Europhys. Lett. Technical Physics and Prototype Engineering Division, Bhabha Atomic Research Center, Mumbai 400 085, INDIA; e-mail gurazada@apsara.barc.ernet.in; A. K. Grover's telephone at TIFR, Mumbai +91 22 215-2971 or -2979; telefax +91 22 215-2181 or -2110; e-mail grover@tifr.res.in. 74.60.-w; 74.25.Ha; 74.25.Dw.

C. T. Rieck, D. Straub, and K. Scharnberg, "Nonlocal Effects on the Surface Resistance of High Temperature Superconductors with (100) and (110) Surfaces." Submitted to J. Supercond. Fachbereich Physik, Universitaet Hamburg, Jungiusstrasse 9, D-20355 Hamburg, GERMANY; D. Straub's e-mail straub@physnet.uni-hamburg.de.

F. Ronning, C. Kim, D. L. Feng, D. S. Marshall, A. G. Loeser, L. L. Miller, J. N. Eckstein, I. Bozovic, and Z.-X. Shen, "Experimental Evidence for a Fermi Surface Remnant with a d-Wave Like Dispersion in Insulating Ca2CuO2Cl2." To be published in Science. Department of Physics, Applied Physics and Stanford Synchrotron Radiation Laboratory, Stanford, CA 94305; telephone (650) 723-5583; telefax (650) 725-5457; e- mail fronning@leland.stanford.edu.

Alexandr V. Rozhkov and Daniel P. Arovas, "Kinky Behavior in Josephson Junctions." Department of Physics, University of California at San Diego, La Jolla, CA 92093; Daniel P. Arovas' e-mail dpa@borges.ucsd.edu; preprint also available at cond-mat@xxx.lanl.gov (#9812085). 74.50.+r; 73.40.Gk.

S.F.W.R. Rycroft, R. A. Doyle, D. T. Fuchs, E. Zeldov, R. J. Drost, P. H. Kes, T. Tamegai, S. Ooi, and D. T. Foord, "Bulk Transport Properties of Bi2Sr2CaCu2O8 Crystals in the Corbino Disk Geometry." Submitted to Phys. Rev. B. Interdisciplinary Research Centre in Superconductivity, University of Cambridge, West Cambridge Site, Madingley Road, Cambridge CB3 0HE, UNITED KINGDOM; telephone +44 1223 33 7049; telefax +44 1223 33 7074; e-mail swrr2@hermes.cam.ac.uk. 74.25.Dw; 74.25.Fy; 74.60.Ge; 74.72.Hs.

P. Schaetzle, G. Krabbes, S. Gruss, and G. Fuchs, "YBCO/Ag Bulk Material by Melt Crystallization for Cryomagnetic Applications." To be published in IEEE Trans. Appl. Supercond. Institute of Solid State and Materials Research Dresden, P.O. Box 270016, D-01171 Dresden, GERMANY; telephone +49 351 4659 408; telefax +49 351 4659 480.

T. Schmauder, B. Frazer, R. Gatt, X. X. Xi, M. Onellion, D. Ariosa, M. Grioni, G. Margaritondo, and D. Pavuna, "Pulsed Laser Deposition for In- Situ Photoemission Studies on YBa2Cu3O7-d and Related Oxide Films." To be published in Superconducting and Related Oxides: Physics and Nanoengineering III, edited by D. Pavuna and I. Bozovic, SPIE Proc. 3481 (SPIE, Bellingham, 1998). Department of Physics, University of Wisconsin at Madison, Madison, WI 53706. Key words: superconducting films, laser ablation epitaxy, photoemission spectroscopy.

T. Schneider and J. M. Singer, "Fundamental Constraints for the Mechanism of Superconductivity in Cuprates." To be published in Eur. Phys. J. B. Contact J. M. Singer, Physik-Institut, Universitaet Zurich, Winterthurerstrasse 190, CH-8057 Zurich, SWITZERLAND; telephone +41 1 635 4017; telefax +41 1 635 5704; e-mail jms@physik.unizh.ch; preprint also available at cond-mat@xxx.lanl.gov (#9812081). 74.20.-z; 74.20.Mn.

T. Schneider and J. M. Singer, "Magnetic Field Induced Dimensional Crossover Phenomena in Cuprate Superconductors and Their Implications." To be published in Physica C. Contact J. M. Singer, Physik-Institut, Universitaet Zurich, Winterthurerstrasse 190, CH-8057 Zurich, SWITZERLAND; telephone +41 1 635 4017; telefax +41 1 635 5704; e-mail jms@physik.unizh.ch; preprint also available at cond-mat@xxx.lanl.gov (#9812082). Key words: high-Tc cuprates, dimensional crossover, fluctuations, xy scaling.

H. Schwer, R. Molinski, E. M. Kopnin, M. Angst, and J. Karpinski, "Single Crystal of the 1223/1234 Intergrowth Phase Hg1.44Re0.5Ba4Ca5Cu7O20: Structure and Properties." To be published in Physica C (in press). Laboratorium fuer Festkoerperphysik, ETH Hoenggerberg, CH-8093 Zurich, SWITZERLAND; telephone +41 1633 2256; telefax +41 1633 1072; e-mail schwer@solid.phys.ethz.ch. Key words: structure of Hg1.44Re0.5Ba4Ca5Cu7O20, Re doping, defect structure, stacking faults.

J. E. Sonier, M. F. Hundley, and J. W. Brill, "Low Field Anomaly in the Specific Heat of s-Wave Superconductors Due to the Expansion of the Vortex Cores." Los Alamos National Laboratory, Los Alamos, NM 87545; e- mail jsonier@mst.lanl.gov; preprint also available at cond- mat@xxx.lanl.gov (#9811420). 74.25.Bt; 74.25.Jb; 74.70.Ad; 74.72.Bk.

T. Startseva, T. Timusk, A. V. Puchkov, D. N. Basov, H. A. Mook, M. Okuya, T. Kimura, and K. Kishio, "Temperature Evolution of the Pseudogap State in the Infrared Response of Underdoped La2-xSrxCuO4." To be published in Phys. Rev. B. Department of Physics and Astronomy, McMaster University, Hamilton, Ontario, CANADA L8S 4M1; T. Timusk's e- mail timusk@mcmaster.ca; preprint also available at cond- mat@xxx.lanl.gov (#9812134). 74.25.Gz; 74.72.Dn; 74.72.Jt; 74.72.-h; 78.20.Ci.

C. E. Stronach, D. R. Noakes, X. Wan, Ch. Niedermayer, C. Bernhard, and E. J. Ansaldo, "Zero-Field Muon-Spin-Rotation Study of Hole Antiferromagnetism in Low-Carrier-Density Y1-xCaxBa2Cu3O6." To be published in Physica C (in press). Department of Physics, Virginia State University, Petersburg, VA 23806; telephone (804) 524-5915; telefax (804) 524-5914; e-mail cstronac@vsu.edu. Key words: muon spin relaxation, Y1-xCaxBa2Cu3O6, doped-hole spin freezing, antiferromagnetic ordering. 74.25.Ha; 74.72.Bk; 76.75.+i.

Ryan L. Thayer, Sarah R. Schmidt, Stephen E. Dorris, Jeffrey W. Bullard, and Michael T. Lanagan, "Reactive Sintering and Retrograde Densification of Bulk Bi-Based Superconductors." Submitted to J. Amer. Ceram. Soc. Contact Janice Coble, Materials Science Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439; telephone (630) 252-5497; telefax (630) 252-9595; e-mail coble@anl.gov.

U. P. Trociewitz, P.V.P.S.S. Sastry, P. R. Sahm, and J. Schwartz, "Flux Pinning Enhancement in Ag-Clad Bi-2212 Wires by Reactive Doping with Barium Peroxide." Submitted to IEEE Trans. Appl. Supercond. National High Magnetic Field Laboratory, Florida State University, 1800 East Paul Dirac Drive, Tallahassee, FL 32310; telephone (850) 644-1447; telefax (850) 644-0867; e-mail trociew@magnet.fsu.edu.

M. Ullrich, H. Walter, A. Leenders, and H. C. Freyhardt, "Batch Production of High-Quality-Customized-Shaped-Monolithic HTSC." To be published in Physica C (in press). Contact A. Leenders, Zentrum fuer Funktionswerkstoffe Goettingen, Windausweg 2, D-37073 Goettingen, GERMANY; telephone +49 551 507 1730; telefax +49 551 507 1750; e-mail leenders@umpsun1.gwdg.de. Key words: superconducting magnets, melt- textured superconductors, crystal growth, Y-based cuprates. 85.25.Ly; 74.80.Bj; 81.10.-h; 74.72.Bk.

H. Utsunomiya, T. Sakai, K. Hatsuda, M. Shinkawa, and Y. Saito, "Improvement of the Critical Current Density of Ag-Sheathed (Bi,Pb)2223 Superconducting Tapes by Tension Rolling." To be published in Physica C (in press). Department of Materials Science and Engineering, School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871, JAPAN; telephone +81 06 879 7503; telefax +81 06 879 7500; e-mail uts@mat.eng.osaka-u.ac.jp. Key words: critical current density, grain alignment, tension rolling, (Bi,Pb)2223, oxide powder-in-tube.

S. Vikram, P. A. Molian, M. D. Shirk, R. E. Koritala, and U. Balachandran, "Influence of Pulse Width and Target Density on Pulsed Laser Deposition of Thin YBaCuO Film." Submitted to the Proc. of the 17th Int. Congress on Applications of Lasers and Electro-Optics, Orlando, Fla., Nov. 16-19, 1998. Mechanical Engineering Department, Iowa State University, Ames, IA 50011; preprint also available from Janice Coble, Materials Science Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439; telephone (630) 252-5497; telefax (630) 252-9595; e-mail coble@anl.gov.

Hiroyuki Yamase, Hiroshi Kohno, Hidetoshi Fukuyama, and Masao Ogata, "Effects of Charge Density Modulation on Incommensurate Antiferromagnetism: Ginzburg-Landau Study." Submitted to J. Phys. Soc. Jpn. Department of Physics, University of Tokyo, Bunkyo-ku, Tokyo 113- 0033, JAPAN; telephone +81 3 3812 2111; e-mail yamase@watson.phys.s.u- tokyo.ac.jp; preprint also available at cond-mat@xxx.lanl.gov (#9812033). Key words: La-based high-Tc superconductors, GL free energy, t-J model, Fermi surface, nesting, 1/8 phenomena, incommensurate antiferromagnetism, charge-density modulation, stripe pattern.

A. Yurgens, D. Winkler, T. Claeson, G. Yang, I.F.G. Parker, and C. E. Gough, "2212-BSCCO Intrinsic Josephson Junctions in a Magnetic Field." Department of Microelectronics and Nanoscience, Chalmers University of Technology, S-41296 Goeteborg, SWEDEN; e-mail yurgens@fy.chalmers.se. 74.50.+r; 74.60.Jg; 74.60.Ge; 74.72.Hs.

B. Y. Zhu, D. Y. Xing, Jinming Dong, and Bairu Zhao, "Dynamical Phase Transition of a Driven Vortex Lattice with Disordered Pinning." To be published in Physica C (in press). National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, PEOPLE'S REPUBLIC OF CHINA; telephone +86 1 6255 9131, ext. 513; telefax +86 1 0256 2605; e-mail byzhu@ssc.iphy.ac.cn. Key words: vortex lattice, pinning, phase transition. 74.60.Ge; 74.60.-w; 74.25.Dw.

COMING EVENTS (An * indicates a previously listed event.)

Feb. 19, 1999: Commercialization of Cryoelectronics Technologies in Microelectronics, San Francisco, Calif. Key areas that will be addressed include packaging, refrigeration, and cost-effectiveness. Abstract deadline, January 15, 1999. For information, contact The Knowledge Foundation, Inc., 101 Merrimac Street, Boston, MA 02114; telephone (617) 367-7979; telefax (617) 367-7912; e-mail custserv@knowledgefoundation.com.

June 21 - 25, 1999: The 7th International Superconductive Electronics Conference (ISEC'99), Berkeley, Calif. One in a series of biennial conferences specifically on superconductive electronics. Conference is held in odd-numbered years and the location circulates among Japan, Europe, and the US. Topics cover all electronics applications, including underlying theory and practical realization. No parallel oral sessions in the main conference. Topics are: SQUID sensors and applications, processing technology, junction fabrication, detectors and mixers, HTS digital, LTS digital, ADC and DAC circuits, analog filters and communication circuits, NMR and MRI, single-frequency sources, and other analog devices and circuits. Appended to the conference this year will be a day of parallel optional workshops (June 25), in which details of particular applications and the related technologies will be discussed in depth. Attendance at the workshops requires an additional registration fee. The following topics are tentatively scheduled for workshop: HTS fabrication, LTS fabrication, SQUID devices, SQUID applications, microwave devices, microwave applications, digital and analog/digital circuits, and digital systems. Abstract deadline, February 15, 1999; early registration deadline, April 30, 1999. For information, contact Ted Van Duzer, Conference Chairman, EECS Department, University of California, Berkeley, CA 94720-1770; telephone (510) 642-3306; telefax (510) 643-8194; e-mail vanduzer@eecs.berkeley.edu. Or contact Conference Administration, Centennial Conferences, 4800 Baseline Road A-112, Boulder, CO 80303; telephone (303) 499-2299; telefax (303) 499-2599; e-mail centennial@orci.com. Information also available at inqueries@isec99.org or the Web site www.isec99.org.

*June 27 - 30, 1999: 1999 International Workshop on Superconductivity (4th Joint ISTEC/MRS Hawaii Workshop), Kauai, Hawaii. Co-sponsored by ISTEC and MRS. Fourth in the series. Theme will be "High-Temperature Superconducting Materials and Devices for Electronics Applications." In particular, topics concerning thin films and processing, and HTS junctions and integration technology will be emphasized. Workshop will consist mainly of a series of single-session meetings with a significant amount of time allotted for the discussion of each paper and extra amounts of time put aside to encourage informal interactions among the participants. Topics of interest (including, but not restricted to the following) are: HTS superconducting materials; characterization (surface roughness, surface resistance, etc.) and processing of thin films (MOCVD, LEP, sputtering, laser ablation, evaporation, etc.); substrates; HTS junctions; devices (microwave & mm-wave devices, SQUIDs, RSFQ/SFQ, JJs, etc.); applications (telecommunication, computing, switching devices, medical, etc.); and others. Contributed Summary deadline, January 15, 1999. For information, contact Tetsuji Kobayashi, Director, International Affairs Department, International Superconductivity Technology Center (ISTEC), Eishin Kaihatsu Bldg. 6F, 34-3, Shinbashi 5-chome, Minato-ku, Tokyo, 105-0004 Japan; telephone +81 3341 4044; e-mail t-kobayashi@istec.or.jp.

*July 7 - 10, 1999: Ninth International Workshop on Critical Currents (IWCC9-99), University of Wisconsin, Madison, Wisc. IWCC9-99 will be the ninth in a series of workshops devoted to study and discussion of the critical current density in superconductors. This three and one- half day workshop will be organized around keynote talks on flux pinning, grain-boundary properties, and the current-limiting mechanisms of single- and polycrystalline superconductors. Extensive discussion time will be given to these key topics. Abstract deadline, January 31, 1999. For further information, contact M. M. Adams, Conference Coordinator, 1500 Engineering Drive, Room 917 ERB, Madison, WI 53706; telephone (608) 263-5029; telefax (608) 263-1087; e-mail iwcc@engr.wisc.edu.

Aug. 17 - 20, 1999: 1999 Taiwan International Conference on Superconductivity (TICS'99) & 6th Workshop on Low Temperature Physics (WLTP6), Kenting, Taiwan, Republic of China. Contributions within superconductivity and low-temperature-physics-related topics are welcome. For information, contact H. D. Yang, Department of Physics, National Sun Yat-Sen University, Kaohsiung, 804 Taiwan; telephone +886 7 5253701; telefax +886 7 5253709; e-mail yang@mail.phys.nsysu.edu.tw; Web site http://www2.nsysu.edu.tw/physics/tics99.

*Aug. 29 - Sept. 10, 1999: NATO Advanced Study Institute (ASI) on Microwave Superconductivity, The Pyrenees Mountains, Spain. This ASI will cover microwave properties of superconductors, the fabrication and measurement of superconducting devices, circuits which operate at microwave frequencies, and technological issues and market potential of all current and emerging microwave applications. Financial awards are available to some students and recent Ph.D.s who are residents of NATO and selected Eastern European countries. Directors: Martin Nisenoff, NRL and Harold Weinstock, AFOSR. Application deadline, January 15, 1999. For application visit Web site www.geocities.com/Pentagon/Quarters/9088 or contact Sandy Ronayne, 110 Duncan Ave., Bolling AFB, DC 20332-8050; e-mail sandy.ronayne@afosr.af.mil.

Sept. 5 - 7, 1999: International Conference on Solid State Spectroscopy (ICSSS), Schwaebisch Gmuend, Germany. To be held in honor of the scientific achievements of Prof. Manuel Cardona. Will consist of oral presentations of 30-45 mins. given by invited speakers. Participants are expected to contribute posters which will be on display throughout the meeting. Ample time will be reserved for casual discussions and the exchange of ideas. No parallel sessions. Conference language is English. Proceedings will be published in a special issue of Phys. Stat. Solidi (b). Participation is limited to 160 participants. Reduced fees will be available for young scientists, who are encouraged to participate. Topics are: Methods -- optical spectroscopy, Raman spectroscopy, electron spectroscopy, x-ray and neutron scattering, and nanoprobes; Materials -- semiconductors, surfaces, heterostructures, interfaces, and low-dimensional systems, high-temperature superconductors, and magnetic oxides. Abstract deadline, January 15, 1999. For information, contact Sabine Birtel, ICSSS, Max-Plank-Institut fuer Festkoerperforschung, Heisenbergstr. 1, D-70569 Stuttgart, Germany; telefax +49 711 689 1712, e-mail icsss@cardix.mpi-stuttgart.mpg.de, Web site http://cardix.mpi-stuttgart.mpg.de/icsss/.

High-Tc Update is the high-Tc superconductivity information exchange newsletter. Please send 1) preprints, reprints, and other research reports; 2) descriptions of on-going work; 3) meeting announcements and summaries.

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
E-mail: MITRA@AMESLAB.GOV or MITRA@IASTATE.EDU

Project Director/Editor: Sreeparna Mitra
Science Editor: John R. Clem
High-Tc Update, Vol. 13, #1, January 1, 1999.