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, and other agencies, organizations, and individuals.

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PLEASE NOTE: Issues of High-Tc Update from November 15, 1993, onward are also available in coded Word versions (BINHEX and RTF). (These versions preserve the Greek letters, special characters, accents, etc.) If you are interested in the alternate formats, contact the editor for information.

PLEASE READ: The electronic-mail version of High-Tc Update is generated from a Macintosh Microsoft Word file and turned into a text file that can be transferred electronically. Formatting commands, Greek symbols, diacritical marks, etc. are lost in this transformation. In order to improve the readability of the e-mail version, the newsletter staff add explanatory marks as needed to the text file. For example, a carat (10^5) indicates a superscript (ten to the fifth). A carat followed by a bracket (cm^[-2]) indicates everything within the brackets is superscripted (centimeter to the minus 2). A bracket followed by a carat ([18]^O) indicates everything before the carat is superscripted. An underline (M_i) indicates a subscript (M subscript i). Most Greek letters are spelled out (Delta, mu, tau, pi, Omega), although delta is left as "d." In most instances, easily recognizable formulas or units are left as they appear: Tc, Jc, YBa2Cu3O7, O2. Mu-m is changed to micrometers. Diacritical marks (accents, tildes, carats, etc.) are removed, but the German umlaut (e.g., a, o, or u with two dots over it) is changed into a, o, or u followed by e. If needed for clarity, hyphens are occasionally inserted between spelled-out Greek letters or symbols (ohm-cm, sin-theta).

NOTA BENE:

RBa2Cu3O7-d

Two preprints by H. Ikuta (Nagoya) et al. report improvements in the melt-processing of RBa2Cu3O7-d (R-Ba-Cu-O, R = Nd and Sm) and significant increases in the flux-trapping ability of the resulting samples. In the first paper, the authors found that adding Ag to the starting materials solves some problems that had been encountered in the melt-processing of large R-Ba-Cu-O bulk superconductors; the addition of Ag was found to prevent the formation of cracks, such that the samples showed no indication of weak links in the trapped magnetic-field profiles at 77 K. Peak values of the trapped magnetic field at 77 K were 0.4 T for a Nd-Ba-Cu-O sample of diameter 18 mm and 0.96 T for a Sm-Ba-Cu-O sample of diameter 33 mm. In the second paper, the authors report measurements of the trapped magnetic field versus temperature in various Sm-Ba-Cu-O samples. At 77 K, the peak trapped field in a sample of diameter 36 mm was 1.7 T, more than twice that of similar-sized melt- processed Y-Ba-Cu-O samples at the same temperature; at 65 K, the peak trapped field was 4.7 T. For a Sm-Ba-Cu-O sample of diameter 30 mm, the trapped field was 8.0 T at 40 K. Further attempts to magnetize the Sm- Ba-Cu-O samples at still lower temperatures resulted in sample cracking because of the strong Lorentz-force-induced tensile stresses that develop as the applied field decreases.

To examine local mechanical properties of melt-textured RBa2Cu3O7-d (R = Y and Nd), R. Provoost (Leuven) et al. have carried out a detailed analysis of micro-Raman spectra recorded around the nonsuperconducting R2BaCuO5 inclusions imbedded in these materials. The Raman spectra were recorded every 0.4 or 0.5 micrometer along a line crossing one or more inclusions on two specific samples. In fast-melt-processed YBa2Cu3O7-d samples, the authors found a softening of the Y-123 Raman modes around inclusions. On the other hand, in oxygen-controlled-melt-grown NdBa2Cu3O7-d samples, where the cooling rate is much lower, the authors observed a hardening of the Nd-123 modes around the Nd4Ba2Cu2O10 inclusions.

The flux-pinning characteristics of ternary melt-processed (Nd0.33Eu0.33Gd0.33)Ba2Cu3Oy (NEG) have been studied by M. R. Koblischka et al. (SRL-ISTEC) in the temperature range 60 K <= T <= 90 K. The authors found that the NEG samples exhibit a strongly developed peak effect in the dependence of the critical current upon the external magnetic field H_a. Scaling of the bulk pinning forces versus the reduced field h = H_a/H_[irr] (H_[irr] is the irreversibility field) yields a peak at h_0 = 0.5, which is an indication that pinning is produced by a spatial variation of the transition temperature.

Magneto-optical investigations have been carried out by A. Das et al. (SRL-ISTEC) to investigate the uniformity of flux penetration and flux trapping in (Nd0.33Eu0.33Gd0.33)Ba2Cu3Oy (NEG) superconductors melt- processed in a reduced oxygen atmosphere. The authors found that the critical state was well established in the entire sample, showing that the sample was a single grain without weak links.

O K-edge and Cu L_[23]-edge x-ray absorption spectra in (Nd1.05- xPrx)Ba1.95Cu3O7-d (x = 0.0-0.5) have been measured by J. M. Chen (SRRC- Hsinchu) et al. to investigate how the variation of hole states relate to the superconductivity in this material. The results demonstrate that the suppression of superconductivity upon substituting Pr into the (Nd1.05-xPrx)Ba1.95Cu3O7-d system arises predominantly from the hole- depletion effect.

Measurements of the electrical resistivity and thermoelectric power in the system Y1-xCaxBa2Cu3O7-d (x = 0 and 0.2) have been carried out by M. Akoshima and Y. Koike (Tohoku) to determine Tc and p, the hole concentration per Cu. The authors conclude that the 60 K plateau of Tc in the Y-123 phase should be attributed to the 1/8 anomaly seen previously in the La-214 and Bi-2212 phases, and not to ordering of oxygen vacancies in the CuO1-d chains. The authors also conclude that it is very likely that dynamical stripe ordering of spins and holes exists in all high-Tc cuprates, and that the behavior of the stripe order at p ~ 1/8 is responsible for the anomalous suppression of superconductivity there.

The magnetoconductivity of YBa2Cu3O7-d has been measured by J. Axnaes et al. (Stockholm) in magnetic fields B up to 12 T in temperatures up to 2.55 Tc for B||c and up to 1.7 Tc for B||ab. The authors found that their data, as well as previously published data, can be well described by including the Maki-Thompson (MT) terms and the previously neglected density-of-states effects. The authors emphasize that all previous analyses neglecting the MT terms must be reexamined.

A preprint by C. P. Bidinosti et al. (UBC) reports measurements of the magnetic-field dependence of the penetration depth lambda(H) for untwinned YBa2Cu3O6.95 for temperatures 1.2-70 K in dc fields up to 42 Oe and directions 0 degree, +-45 degrees, and 90 degrees with respect to the crystal b-axis. The experiment used an ac susceptometer with fields applied parallel to the ab-plane of thin platelet samples. At low temperatures, the authors found the field dependence of Delta[lambda] = lambda(H) - lambda(0) to be essentially linear in H, ranging from 0.04 Angstrom/Oe for Delta[lambda_a] to 0.10 Angstrom/Oe for Delta[lambda_b], values comparable with the T = 0 Yip and Sauls prediction for a d-wave superconductor. However, the authors report that the systematics versus temperature and orientation do not agree with the d-wave scenario, probably due in part to residual sample problems.

Bi Cuprates

Using constant-initial-energy angle-scanning photoemission, supported by energy distribution curves, N. L. Saini (Roma) et al. have studied topological features of the Bi2Sr2CaCu2O8+d (Bi-2212) Fermi surface. The resulting Fermi surface measured over an extended Brillouin zone shows broken segments with partial gaps around (pi,0) and shadow bands around (0.5pi,0.5pi) and equivalent locations. The data also provide evidence for new electronic states at the Fermi surface due to a one- dimensional band with small dispersion and small k_F along the (pi,0) direction. The authors argue that these features are related to charge ordering in the CuO2 plane along the (-pi,pi) direction and spin fluctuations along the (pi,0) direction.

Reversible magnetization measurements with applied field parallel to the c-axis have been carried out by X. Zhao (Hefei) et al. for a series of Bi-2212 single crystals with different oxygen content varying from undoped to overdoped states. The authors analyzed the magnetization versus temperature to obtain both Tc and (via lambda_[ab]) n_s/m*. A deviation from a linear relationship between Tc and n_s/m* was observed. The authors explain the deviation in the underdoped region as a result of structural distortion and disorder scattering, and in the overdoped region as a consequence of phase-separation-related pair breaking.

The effect of Pr doping on the structure and superconductivity of the Bi-2212 system is described in two papers by X. Sun (Hefei) et al., who prepared Bi2Sr2Ca1-xPrxCu2Oy single crystals with x = 0-0.78. The superconducting transition temperature increases slightly at first and then drops gradually with Pr doping, with complete suppression of superconductivity occurring when x = 0.60.

Periodic pressing has been used by F. Marti et al. (Geneve) to achieve critical current densities of Pb-containing multifilamentary Ag-sheathed Bi-2223 tapes up to about 3.5 x 10^4 A/cm^2 at 77 K in self-field. This corresponds to a 30-40% increase over the values obtained for conventionally rolled tapes starting with the same powders. The periodically pressed tapes also were found to be less sensitive to the duration of the first annealing time. The authors present a brief description of the periodic pressing machine, and they stress that this technique is a practical, scalable process for the fabrication of long lengths of Bi-2223.

A factor of ~1.5 enhancement in critical current I_c of a Bi-2223/Ag tape has been achieved by T. Chiba (Brookhaven) et al. through the use of a preheat treatment, 600^oC for 6 h, prior to the final heat treatment at 840^oC. This treatment also resulted in improvements in the resistive transition width and specimen-to-specimen reproducibility. The authors suggest that better intergranular connectivity, rather than enhanced vortex pinning strength, is responsible for the improvements.

Global transport measurements and local Hall-probe-array measurements have been carried out by Y. Radzyner (Bar-Ilan) et al. on a section of silver-clad Bi-2223 tape. The two methods show good agreement at low temperatures and low fields but diverge at high temperatures and relatively high fields. Under the latter conditions, the currents induced by the magnetic field tend to flow within the grains, while the transport current must flow along the sample. The "brick-wall" model aptly describes the flow of transport currents but fails to describe the flow of intragranular currents induced by an external magnetic field.

LSCO

Electronic Raman continua of La2-xSrxCuO4 single crystals with various levels of doping have been measured by O. V. Misochko (ISSP- Chernogolovka) and S. Uchida (Tokyo) for light polarized both within the CuO2 planes and along the c-axis. For the two cases, different doping dependencies of the A_[1g] scattering strength in the normal state were observed. Based on the redistribution of the continua below Tc, the authors infer that the superconducting energy gap is anisotropic, although evidence for pure d-wave pairing (omega^3 low-frequency behavior) is absent at any doping.

Vortices

Sub-nanovolt-resolution longitudinal and Hall voltages have been measured by G. D'Anna (EPFL) et al. in an ultrapure YBa2Cu3O7-d single crystal. The Hall anomaly and the first-order vortex-lattice melting transition were observed simultaneously. Changes in the dynamic behavior of the vortex solid and liquid were found to be correlated with features of the Hall conductivity sigma_[xy]. With the magnetic field oriented at an angle from the twin boundaries, the Hall conductivity was found to sharply decrease toward large negative values for temperatures decreasing below the vortex-lattice melting transition.

A phase transition within the molten phase of the Abrikosov vortex system without disorder in extreme type-II superconductors has been found by A. K. Nguyen and A. Sudbo (Trondheim) via large-scale Monte Carlo calculations. It involves breaking a U(1) symmetry, and it has a zero-field counterpart, unlike vortex-lattice melting. Its hallmark is the loss of number conservation of connected vortex paths threading the entire system in any direction, driving the vortex line tension to zero. This tension plays the role of a generalized stiffness of the vortex liquid and serves as an order parameter for the transition, at which a weak specific heat anomaly is predicted. The authors discuss the interplay between this new transition and the vortex-lattice-melting transition, and they suggest an experimental test.

A theory of quasiparticle transport in the mixed state of a d-wave superconductor has been developed by M. Franz (Johns Hopkins) under the assumption of a disordered vortex array. The author identifies a universal regime at fields above H* = c*H_[c2](T/Tc)^2, characterized by a field-independent longitudinal thermal conductivity kappa_[xx]^e. The author argues that this behavior is responsible for the high-field plateau in kappa_[xx]^e experimentally observed in high-Tc cuprates [K. Krishana et al., Science 277, 83 (1997); H. Aubin et al., Science 280, 9a (1998)].

Vortex creep in layered superconductors of finite thickness with columnar defects has been theoretically investigated by T. Droese and C. Morais Smith (Hamburg). The authors find that a crossover from rigid to elastic vortex creep occurs when the sample thickness, external driving current, or the pinning strength of the defect is varied. The authors study the crossover behavior in detail for currents J close to the critical current density Jc (Jc - J << Jc).

As pointed out by L. Burlachkov et al. (Bar-Ilan), numerical studies of flux creep in superconductors show that the distribution of the magnetic field at any stage of the creep process can be well described by the condition of spatial constancy of the activation energy, independent of how U depends upon the field B and current density J. The authors formulate a semi-analytical approach to the creep problem and generalize the logarithmic solution for flux creep, obtained for U = U(J), to the case that U has a strong dependence upon B.

The transport-current distribution in clean 2H-NbSe2 crystals has been studied by Y. Paltiel (Weizmann Institute) et al. by measuring the self- induced magnetic field across the sample using a linear Hall array with 19 sensors. The authors found that below Tc most of the current flows at the edges of the crystals because of strong surface barriers, which dominate the transport properties and the resistive transition. The measured critical current is thus determined by the critical current for vortex penetration through the surface barrier rather than by bulk pinning.

ac Losses

A method to measure true ac losses in superconducting cables has been developed by M. Daeumling (NKT) et al. The authors carry out a resonant current experiment, which they call RESCUE, in which a capacitor is short-circuited with the cable, and the decay of the voltage or current oscillations in the resonant circuit is measured as a function of time. The decay rate has two components, a purely exponential one, due to Ohmic dissipation in the leads and contacts, and a non-exponential one, due to hysteretic losses in the superconductor. The authors have used this method to measure the ac losses in a superconducting cable model of length 1 m.

Using a linear spline approximation for the E-J characteristics of a superconductor and representing the solution in the form of a series, V. Sokolovsky et al. (Ben-Gurion University of the Negev) have derived analytical expressions for ac losses. The authors assert that these expressions explain experimentally observed frequency and magnetic-field dependencies of ac losses. The authors also show how the analytical solutions can be applied for various forms of E-J characteristics by defining effective critical current densities and flux-flow resistivities.

Thin Films

A preprint by N. Kim et al. (Pohang) reports the fabrication of small- size stacks on the surface of Bi2Sr2CaCu2O8+d (Bi-2212) single crystal with bulk transition temperature Tc ~~ 90 K, each containing a few intrinsic Josephson junctions. Below a critical temperature Tc' = 35 K, the authors observed a weakened Josephson coupling between the CuO2 superconducting double layer at the crystal surface and the adjacent bilayer deeper in the stack. The quasiparticle branch in the I-V data of the weakened Josephson junction fits well to the tunneling characteristics of a d-wave superconductor/insulator/d-wave superconductor (D'ID) junction. The tunneling resistance in the range Tc' < T < Tc agrees well with the tunneling in a normal metal/insulator/d-wave superconductor (NID) junction.

As reported by S. Sakai et al. (ETL), in the growth of Bi-Sr-Ca-Cu-O (BSCCO) films by molecular-beam epitaxy (MBE), the sticking coefficients of Sr, Ca, and Cu are unity, but that of Bi is very sensitive to growth temperature. Moreover, the temperature dependence of the Bi sticking coefficient for growth of Bi2O3 is very different from that for BSCCO. The authors point out that this property leads to a useful self-limiting function for growth of Bi-based multi-element oxides, and they demonstrate this for MBE growth of Bi2Sr2CuO6 (Bi-2201) and Bi4Ti3O12 (BiT).

When NdBa2Cu3O7-d single crystals are used as the target to produce NdBa2Cu3O7-d films by pulsed-laser deposition (PLD), smooth, nearly droplet-free films have been obtained, in contrast to the case when polycrystalline sintered targets are used. To understand the reasons for the differences, Y. Li et al. (SRL-ISTEC) have studied the surfaces of both kinds of PLD targets and found major differences in their surface morphologies. After a long period of laser ablation, the sintered target displays a cone-shaped columnar surface morphology, while the single-crystal target exhibits a continuous, smooth, undulating morphology with ridges and grooves.

Using a sapphire dielectric resonator method, M. V. Jacob (James Cook and Delhi) et al. investigated the effect of Ag on the 25 GHz microwave properties of superconducting YBCO thin films prepared by PLD on MgO substrates. The authors found that when the Ag doping level in the targets was increased from 2 to 10 wt% Ag, the surface resistance of the resulting YBCO films decreased by 20%, which correlated with improved microstructure of the films.

Various technology issues in deposition of high-temperature superconducting YBCO thin films by reactive evaporation are discussed by V. C. Matijasevic and P. Slycke (Conductus). The key elements are oxygen pocket heaters and sensitive atomic beam monitors. Tunable-diode laser sensors seem to be the most promising technology for vapor flux measurement and control.

Modifications of a commercial atomic force microscope (AFM) have been made by O. Schneegans et al. (Paris), enabling the authors to obtain simultaneous topographical and local contact resistance surface images of YBCO films within the same area of the sample. The authors fitted the AFM with a conducting probe, made of doped silicon coated with doped diamond.

YBCO thin films have been grown by H.-U. Habermeier et al. (MPI- Stuttgart) on vicinal cut SrTiO3 (001) single crystals. The films show a pronounced anisotropy in both the resistivity and flux-pinning properties in the substrate plane. The anisotropy is caused by planar defects generated via self-organization of the YBCO, leading to an exceptionally large critical current density up to 8 x 10^7 A/cm^2 at 4.2 K.

Measurements of the complex ac sheet impedance of c-axis-oriented YBCO thin films have been measured by M. Calame et al. (Neuchatel) in the frequency range 10^2-10^5 Hz for film thicknesses varying between 24 Angstroms and 1100 Angstroms. The authors present measurements for the thinnest films and examine their consistency with predictions of the Kosterlitz-Thouless theory for the vortex-antivortex unbinding transition.

A paper by F. Lombardi et al. (Goeteborg) reports studies of the electrical transport properties of the grain boundaries (GBs) formed at the top and bottom edges of YBCO step-edge Josephson junctions for different values of the step angle alpha. The authors took advantage of the shadowing effect to define a superconducting electrode contacting the superconductor between the top and bottom grain boundaries. In this way, the authors could determine, for example, that for alpha ~~ 60 degrees, the top GB is responsible for the weak-link behavior of the step-edge junctions.

Measurements of the temperature dependence of the critical current density Jc(T) and the current dependence of the energy barrier against vortex motion U_[eff](J) in epitaxial c-axis-oriented YBCO and TBCCO films are reported by J. Jung (Alberta) et al. The authors carried out measurements on rings in a persistent mode using a scanning Hall probe that can measure both the axial (parallel to the c-axis) and the radial (parallel to the ring's surface) components of the persistent current's self-field. The authors found that both Jc(T) and U_[eff](J) appear to be governed by Josephson nanostructures in the ab-planes of YBCO and TBCCO.

A preprint by O. M. Stoll (Tuebingen) et al. reports the observation of a novel intrinsic step structure in the flux-flow resistance of epitaxial c-axis-oriented films of Nd2-xCexCuO4 as a function of current at intermediate magnetic fields B_[c1] << B < B_[c2]. The effect was observed only when the sample was cooled with superfluid helium. To explain the underlying instability, the authors propose a model based on the strongly energy-dependent density of states available near the Fermi energy for quasiparticle scattering in the superconducting mixed state in the clean limit.

The effect of spin-polarized injection on the superconducting order parameter has been investigated by M. S. Osofsky (NRL) et al. in a device consisting of YBa2Cu3O7-d/Au/Ni0.8Fe0.2 layers. The authors present a nonequilibrium theory that qualitatively agrees with the experiment but predicts injection currents that are several orders of magnitude too large.

Thick Films

High-rate evaporation techniques have been used by V. F. Solovyov (Brookhaven) et al. to deposit Y, BaF2, and Cu precursor films onto SrTiO3 single-crystal substrates at rates in excess of 10 nm/s. Y and Cu were deposited by electron-beam heating, and thermal heating was used for BaF2. Post-deposition annealing was used to form 3 micrometers thick c-axis-oriented YBCO films. Critical current densities of 1.8 x 10^5 A/cm^2 at 1 T (H||c) and 77 K were achieved. The results indicate that the BaF2 post-annealing process is one of several possible candidate methods for the production of thick YBCO coatings for large- scale applications.

As reported by S. Miura et al. (SRL-ISTEC), thick YBCO films have been grown on MgO (100) by liquid-phase epitaxy. Transmission electron microscopy (TEM) images revealed that the films consisted of large grains whose misorientation angles were less than 1 degree. Although dc critical current density values decreased with increasing film thickness, even a 7 micrometers thick film had a Jc of 9 x 10^5 A/cm^2 in zero field at 77 K. These and further measurements suggest that LPE- grown YBCO films have superior dc and rf electrical properties.

Applications

The use of a cryogenic near-field scanning microwave microscope to image microwave electric fields from superconducting and normal-metal microstrip resonators is described in a preprint by A. S. Thanawalla (Maryland) et al. The microscope employs an open-ended coaxial probe and operates from 77 K to 300 K in the 0.01-20 GHz frequency range with a spatial resolution of about 200 micrometers. The authors describe the operation of the system and present microwave images of Cu and Tl2Ba2CaCu2O8+d (Tl-2212) microstrip resonators, showing standing-wave patterns at the fundamental and second-harmonic frequencies.

As reported by U. Mizutani (Nagoya) et al., the pulsed-field- magnetization (PFM) technique is the most efficient tool in magnetizing melt-processed high-Tc bulk superconductors in the temperature range 30- 80 K. Having analyzed the process of flux penetration, the authors have developed a procedure called IMR, involving iterative magnetizing pulsed fields with reducing amplitudes, which has been found to be effective in magnetizing melt-textured YBCO superconductors at temperatures down to 30 K. Using these findings, the authors constructed a prototype quasi- permanent magnet system capable of producing a magnetic field of 0.8 T at a height of 7 mm above the surface of a YBCO superconductor (diameter 35 mm and height 14 mm) magnetized by PFM at 30 K.

The fabrication of metal-sheathed high-Tc superconducting current leads with Jc = (1.6-1.8) x 10^4 A/cm^2 at 77 K under self-field conditions is described in a preprint by J.K.F. Yau (Hong Kong, CSIRO, and University of New South Wales) et al. The authors found that section-wise uniaxial pressing could be used to provide the necessary intermediate mechanical deformation between heat treatments of silver-sheathed (Bi,Pb)2Sr2Ca2Cu3O10+d superconducting tapes.

Theory

In a preprint by B. Janko (Chicago) et al., the authors argue that incoherent pair tunneling in a cuprate superconductor junction with an optimally doped superconducting and an underdoped normal lead can be used to detect the presence of pairing correlations in the pseudogap phase of the underdoped lead. The authors estimate that the junction characteristics most suitable for studying the pair tunneling current are close to those in recently fabricated tunneling devices.

The pairing pseudogap in the spectral function has been studied by G. Preosti (Argonne) et al. as a function of interplane coupling. The authors obtain analytical expressions for the self-energy in the critical regime for any degree of anisotropy. The authors find that the frequency dependence of Sigma(omega) is qualitatively different in two and three dimensions, and they discuss the crossover from two- to three- dimensional behavior. By considering the anisotropy of the Fermi velocity and gap along the Fermi surface, the authors can qualitatively explain recent photoemission experiments on high-temperature superconductors concerning the temperature-dependent Fermi arcs seen in the pseudogap phase.

The role of collective modes in various experiments on the cuprates has been investigated by T. Dahm (MPI-Dresden) et al. The authors calculate the neutron-scattering, photoemission (ARPES), and Raman-scattering intensities below Tc within the fluctuation-exchange (FLEX) approximation for the two-dimensional Hubbard model. The authors show that the large peak in the dynamical spin susceptibility arises from a weakly damped spin-density-wave collective mode. This gives rise to a dip between the sharp low-energy peak and the higher-binding-energy hump in the ARPES spectrum. The authors also show that the collective mode of the amplitude fluctuation of the d-wave gap yields a broad peak above the pair-breaking threshold in the B_[1g] Raman spectrum.

Electronic correlations in the ground state of an idealized infinite- layer high-Tc compound have been computed by G. Stollhoff (MPI- Stuttgart) using the ab-initio method of local ansatz. Using this method, the author shows how details of the correlation functions and a good understanding of the relevant short-range correlation features can be obtained. The first application for a metallic high-Tc compound shows a fairly good agreement between the computed and measured magnetic correlation functions.

The phase diagram of a generalized t-J model taking superconducting, flux, and charge-density-wave states into account has been derived by E. Cappelluti and R. Zeyher (MPI-Stuttgart). The investigation was based on the leading expressions of a 1/N expansion enforcing the constraints by means of X-operators. The authors found a strong competition between d-wave superconducting and d-wave flux states. As a result, the transition temperature Tc for superconductivity showed a maximum near a doping value d = d_c ~ 0.13 for J/t = 0.3.

By carrying out a canonical transformation of the three-band Hubbard model, M. Cini et al. (Roma) show how one can obtain an effective Hamiltonian that describes the propagation of a pair of dressed holes, including all many-body effects.

The combined effect of both nonmagnetic and magnetic impurities on the superconducting transition temperature has been studied by L. A. Openov (Moscow State Engineering Physics Institute) within the BCS model. The author derives an expression for the critical temperature as a function of potential and spin-flip scattering rates for a two-dimensional superconductor with arbitrary in-plane anisotropy of the superconducting order parameter, ranging from isotropic s-wave to d-wave (or any pairing state with nonzero angular momentum) and including anisotropic s-wave and mixed (d+s)-wave as particular cases. This expression generalizes the well-known Abrikosov-Gor'kov formula for the critical temperature of impure superconductors.

Properties of low-energy excitations in one-dimensional superconductors and density-wave systems have been examined by M. I. Salkola (Florida State and Stanford) and J. R. Schrieffer (Florida State). The authors find that in addition to the usual spin and charge quantum numbers, a new, independently measurable attribute is required to describe elementary low-energy excitations: the winding number w, which determines, in multiples of pi, how many times the phase of the order parameter winds as an excitation is transposed from far left to far right. The corresponding topological excitations can be viewed as composite particles made of spin or charge degrees of freedom and dressed by kinks in the order parameter.

Other Activities

A preprint by V. V. Moshchalkov et al. (Leuven) reports a comparison of the resistivity rho(T) of the underdoped cuprates with that of the even- chain spin-ladder (SL) compound Sr2.5Ca11.5Cu24O41 under pressure. The SL rho(T) data are fitted by the 1D quantum transport model. Taking into account the scaling behavior at T < T* of the resistivity of the underdoped cuprates YBa2Cu4O8 and YBa2Cu3Ox to that of Sr2.5Ca11.5Cu24O41, the authors assume that the former are also in the 1D regime at temperatures Tc < T < T*. In this interpretation, the pseudogap of underdoped high-Tc cuprates is simply the spin gap of the even-chain SL's associated with stripe formation in the CuO2 planes at T < T*.

Four strategies for increasing the critical temperature of new superconductors are proposed in a preprint by M. Marezio et al. (Parma). These are based on (i) band-structure calculations, which may lead to systems different from known ones; (ii) high-resolution electron- microscopy studies, which may lead to different structural arrangements within the same systems; (iii) systematic studies of phase diagrams; and (iv) in-situ high-pressure studies of the critical temperature of known systems, which may lead to cation or anion substitutions simulating at ambient pressure the structure stable under pressure and responsible for the higher Tc.

As reported by N. Markovic et al. (Minnesota), the superconductor- insulator transition in ultrathin films of amorphous Bi can be tuned by changing the film thickness, with and without an applied magnetic field. The authors present an experimentally determined phase diagram for T = 0 as a function of thickness and magnetic field. The authors performed a finite-size scaling analysis to determine the critical exponent nu-z, which was found to be 1.2+-0.2 for the zero-field transition and 1.4+- 0.2 for the finite-field transition. Both results differ from the exponents found for the magnetic-field-tuned transition in the same system, 0.7+-0.2.

Overviews

A book chapter by J. M. Tranquada (Brookhaven) discusses phase separation, charge segregation, and superconductivity in the layered cuprates. In La2CuO4+d, oxygen interstitials are mobile near room temperature, giving a homogeneous phase, while cooling to lower temperatures can lead to segregation into phases with distinct oxygen concentrations. In La1.6-xNd0.4SrxCuO4+d, the experimental evidence appears to be consistent with a picture in which the holes doped into the planes segregate into stripes that act as domain walls between antiferromagnetic domains, with a pi phase shift across the domain walls. A dynamical form of this modulation provides one model for interpreting the spin correlations in La2-xSrxCuO4 and YBa2Cu3O6+x (181 refs.).

Some of the major experimental features of microwave nonlinearity in high-temperature superconductors, both intrinsic and extrinsic, are reviewed by S. M. Anlage et al. (Maryland). The elimination or control of nonlinearities in these materials will require a microscopic understanding of the defects and geometrical features that produce extrinsic forms of nonlinearity. The authors believe the best route to this goal is through a quantitative microscopic imaging of materials properties, electromagnetic fields, and currents at microwave frequencies and cryogenic temperatures (92 refs.).

The physical mechanisms of microwave losses in high-Tc superconductors, especially at high power levels, are discussed in an overview by M. Golosovsky (Hebrew University of Jerusalem). The author uses an impedance-plane analysis as a tool for quantitative comparison of experiment and theory. The author discusses several models of nonlinear microwave performance of high-Tc superconductors, including coupled- grain and rf critical-state models, and estimates their characteristic time scales (71 refs.).

A review of some of the systematics of the thermoelectric power of cuprates and other superconductors (Ni-Zr, Ni-Zr-Al, Chevrel-phase compounds, K3C60, NbN, and Ba1-xKxBiO3) has been prepared by A. B. Kaiser and G. C. McIntosh (Victoria University of Wellington). The authors present data and discuss some possibilities for explaining the behavior of the thermopower (52 refs.).

Some non-accelerator high-frequency applications of superconductors are reviewed by S. M. Anlage et al. (Maryland). These include the use of high-Tc superconductors in front-end band-pass filters in cellular telephone base stations, the high-temperature superconductor space experiment (the HTSSE program), and high-speed digital electronics. The authors also present an overview of their work on a near-field scanning microscope that can be used to investigate the microwave properties of metals and dielectrics on length scales as small as 1 micrometer (37 refs.).

As noted in a brief review by M. Murakami (SRL-ISTEC), R-Ba-Cu-O superconductors with R-Ba solid solution (R = Nd, Sm, Eu, and Gd) exhibit Tc and Jc values higher than those of melt-textured Y-Ba-Cu-O when they are melt-processed in a reduced oxygen atmosphere. The author points out some important microstructure and processing issues that need to be addressed in studying the R-Ba-Cu-O systems, which have more complicated phase relations than the Y-Ba-Cu-O system (23 refs.).

Contributed by John R. Clem

Contents: Technology News begins on page 7; Preprints begin on page 8; Coming Events begin on page 16; Resources are on page 17; and FYI is on page 17.

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.

TECHNOLOGY NEWS (Also see Applications section of Nota Bene.)

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.

An agreement between American Superconductor Corporation (ASC) and Carolina Power & Light (CPL) was signed recently to distribute ASC's line of industrial power quality solutions based on superconducting magnetic energy storage (SMES) technology. Normal operation of electric utility grids is designed to minimize power outages. However, severe weather, traffic accidents and unforeseen equipment failures can lead to power interruptions or voltage sags. According to industry data, these momentary interruptions and voltage sags cost U.S. industries billions of dollars annually in damaged equipment and lost production.

Housed in a portable 48-foot trailer, American Superconductor's SMES products use an energy storage electromagnet made with low-temperature superconducting wire. SMES units use power electronics to sense momentary electrical power disturbances, more than 80 percent of which last less than two seconds, and instantly provide supplemental power to eliminate the disturbance. Once incoming electric power is stabilized, machinery is switched back to the utility power source. American Superconductor accomplished the first successful marriage of HTS current leads with its low-temperature SMES product line in the AmeriMark installation. The addition of HTS technology to the SMES system decreased American Superconductor's manufacturing costs significantly and decreased SMES annual electrical operating costs for the customer by about 55 percent.

Under the terms of the agreement, CP&L, which generates and provides electricity and energy services to more than 1.1 million customers in the Carolinas, will market American Superconductor's SMES units to its commercial and industrial customers through a dedicated sales force. American Superconductor will provide sales and customer service training and technical support for CP&L sales and engineering personnel.

The agreement formalizes a six-year working relationship between American Superconductor and CP&L. The two companies participated in an Electric Power Research Institute project involving installation and testing of SMES units in various industrial settings in CP&L's service area. For further information please contact Kathy Cadigan, Corporate Communications, American Superconductor Corporation, Two Technology Drive, Westborough, MA 01581; telephone (508) 836-4200 ext. 222.

Conductus, Inc., announced an award of $1.67 million over two years to develop low-loss tunable microwave devices for applications in wireless and satellite communications with an option for a two-year continuation of the program for another $2.2 million. Under this project, Conductus will team with Space Systems Loral to develop the technology necessary for a broad range of advanced wireless products for both terrestrial commercial applications as well as military and space-based applications. Conductus will work to develop tunable filters using thin-film tunable-dielectric materials and high-performance, HTS filter technology. Technology developed under the new program could lead to lower costs in manufacturing existing products as well as to advanced new products for the wireless industry. Among the possibilities for new products are filters that can be electrically and rapidly tuned to different frequency bands and whose characteristics can be altered to meet specific application requirements. Such technology is of interest to both commercial and military customers for terrestrial as well as satellite applications.

The initial effort will be to develop tunable dielectrics and fabrication processes to achieve high-quality materials with intrinsic figures-of-merit (such as tunability and loss characteristics) offering improvements at least ten times the performance currently achieved in state-of-the-art research labs. The reactive evaporation technology Conductus uses in its filter manufacturing process will be utilized for large-area deposition of tunable dielectric materials. Together with Loral, Conductus will then utilize these high-performance tunable dielectric thin films for low-loss tunable microwave devices for wireless and satellite communications. This project is part of a DARPA- sponsored initiative known as FAME (Frequency Agile Materials for Electronics) whose overall goal is to develop hybrid structures for frequency-agile filters, antennas, oscillators, and phase shifters utilizing field dependent properties of ferroelectrics, ferrites and other novel materials. For further information, contact Conductus, Inc., 969 W. Maude Avenue, Sunnyvale, CA 94086, telephone (408) 523- 9950; telefax (408) 523-9999.

Contributed by Sreeparna Mitra

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.

C. H. Ahn, T. Tybell, L. Antognazza, K. Char, M. R. Beasley, C. Beeli, P. Stadelmann, O. Fischer, and J.-M. Triscone, "Electronic Nanofeatures in Epitaxial Ferroelectric Oxide Heterostructures." 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). Departement de Physique de la Matiere Condensee, Universite de Geneve, 24 quai Ernest-Ansermet, CH-1211 Geneve 4, SWITZERLAND. Key words: epitaxial oxide films, ferroelectrics, field effect.

Megumi Akoshima and Yoji Koike, "On the 60 K Plateau of Tc in Y1- xCaxBa2Cu3O7-d in Relation to the 1/8 Problem." To be published in J. Phys. Soc. Jpn. Department of Applied Physics, Graduate School of Engineering, Tohoku University, Aramaki Aoba 08, Aoba-ku, Sendai 980- 8579, JAPAN; telefax +81 22 217 7977; telefax +81 22 217 7975; e-mail akoshima@teion.apph.tohoku.ac.jp. Key words: Y-123 phase, oxygen content, superconducting transition temperature, electrical resistivity, thermoelectric power, hole concentration, orthorhombic-tetragonal transition, 60 K plateau, 1/8 problem.

E. B. Amitin, V. Ya. Dikovsky, A. N. Lavrov, and A. P. Shelkovnikov, "Scaling Behavior in Normal-State Properties of Underdoped TmBaCuO Single Crystals." Contact V. Ya. Dikovsky, Institute of Inorganic Chemistry, Lavrentieva Ave. 3, Novosibirsk 630090, RUSSIA; telefax +7 383 2 344 489; e-mail dikovsky@casper.che.nsk.su. Key words: resistivity, scaling, pseudogap.

Steven M. Anlage, Wensheng Hu, C. P. Vlahacos, David Steinhauer, B. J. Feenstra, Sudeep K. Dutta, Ashfaq Thanawalla, and F. C. Wellstood, "Microwave Nonlinearities in High-Tc Superconductors: The Truth is Out There." Submitted to J. Supercond.: Proc. of the HTS-RF-98 Conference, Stockholm, Sweden. Center for Superconductivity Research, Department of Physics, University of Maryland, College Park, MD 20742-4111; B. J. Feenstra's telephone (301) 405-6132; telefax (301) 314-9541; e-mail feenstra@squid.umd.edu; preprint also available at cond-mat@xxx.lanl.gov (#9808194).

Steven M. Anlage, C. P. Vlahacos, D. E. Steinhauer, S. K. Dutta, B. J. Feenstra, A. Thanawalla, and F. C. Wellstood, "Low Power Superconducting Microwave Applications and Microwave Microscopy." Presented at the 8th Workshop on rf Supercond., Abano Terme, Italy, Oct. 8, 1997; to be published in Particle Accelerators. Center for Superconductivity Research, Department of Physics, University of Maryland, College Park, MD 20742-4111; B. J. Feenstra's telephone (301) 405-6132; telefax (301) 314-9541; e-mail feenstra@squid.umd.edu; Web site http://www.csr.umd.edu; preprint also available at cond-mat@xxx.lanl.gov (#9808195).

F. Auguste, A. Rulmont, N. Vandewalle, M. Ausloos, and R. Cloots, "Isothermally Melt-Textured Grown Single Domains of RE-123 (RE=Dy, Gd, Y,...) Using Nd- and Sm-123 Single Crystals as a Seed." Submitted to the Proc. of the 9th World Ceramic Congress and Forum on New Mater. (CIMTEC'98), Florence, Italy, June 14-19, 1998. Contact R. Cloots, SUPRAS, Chemistry Institute B6, University of Liege, Sart-Tilman, B-4000 Liege, BELGIUM; e-mail cloots@gw.unipc.ulg.ac.be.

F. Auguste, N. Vandewalle, M. Ausloos, J. McManus-Driscoll, A. Rulmont, and R. Cloots, "The Nd-123 Superconducting System: From Single Crystal to Top-Seeded Large Grain -- Physical and Chemical Parameters Influence." To be published in Appl. Supercond. (in press). SUPRAS, Chemistry Institute B6, University of Liege, Sart-Tilman, B-4000 Liege, BELGIUM; R. Cloots' e-mail cloots@gw.unipc.ulg.ac.be.

J. Axnaes, B. Lundqvist, and OE. Rapp, "High-Temperature Magnetoconductivity of YBa2Cu3O7-d: Reconsideration of the Maki- Thompson Contribution." To be published in Phys. Rev. B. Department of Solid State Physics, Royal Institute of Technology, S-100 44 Stockholm, SWEDEN; telephone +46 8 790 7871; telefax +46 8 790 6952; e-mail johan@ftf.kth.se. 74.25.Fy; 74.40.+k; 74.72.Bk.

Yunkyu Bang, "New Gap Equation for a Marginal Fermi Liquid." Department of Physics, Chonnam National University, Kwangju 500-757, KOREA; e-mail ykbang@chonnam.chonnam.ac.kr; preprint also available at cond- mat@xxx.lanl.gov (#9808014). 74.20.Fg; 74.20.Mn.

P. Bernstein, M. Pannetier, C. Picard, Ph. Lecoeur, O. Riou, M. Hanotel, J. F. Hamet, T. D. Doan, and J. P. Contour, "Vortex Dynamics in YBCO Films with a Low Applied Field." 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). Laboratoire Universitaire des Sciences Appliquees de Cherbourg, F-50130 Octeville, FRANCE. Key words: high-Tc superconductive films, vortex diffusion, flux creep, flux flow.

C. P. Bidinosti, W. N. Hardy, D. A. Bonn, and Ruixing Liang, "Measurements of the Magnetic Field Dependence of lambda in YBa2Cu3O6.95: Results as a Function of Temperature and Field Orientation." Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, BC, CANADA V6T 1Z1; e-mail bidinost@physics.ubc.ca; preprint also available at cond- mat@xxx.lanl.gov (#9808231). 74.25.Nf; 74.25.Ha; 74.72.Bk; 74.90.+n.

Dave H. A. Blank, Gertjan Koster, Guus J.H.M. Rijnders, and Horst Rogalla, "In-Situ Monitoring During Pulsed Laser Deposition of Layered Oxide Materials." 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). University of Twente, P.O. Box 217, 7500 AE Enschede, THE NETHERLANDS; e-mail d.h.a.blank@tn.utwente.nl; Web site http://www-lt.tn.utwente.nl/lt/. Key words: pulsed laser deposition, RHEED, SrTiO3, relaxation, interval deposition.

L. Burlachkov, D. Giller, and R. Prozorov, "Collective Flux Creep: Beyond the Logarithmic Solution." Department of Physics, Institute for Superconductivity, Bar-Ilan University, Ramat-Gan 52900, ISRAEL; R. Prozorov's e-mail prozorr@mail.biu.ac.il; preprint also available at cond-mat@xxx.lanl.gov (#9802076).

M. Calame, Ch. Leemann, L. Baselgia Stahel, and P. Martinoli, "Effect of Pinning and Thermal Fluctuations on the Superconducting Transition of YBa2Cu3O7 Very Thin 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). Institut de Physique, Universite de Neuchatel, CH-2000 Neuchatel, SWITZERLAND. Key words: thin films, Kosterlitz-Thouless transition, fluctuations, pinning, vortices.

E. Cappelluti and R. Zeyher, "Interplay Between Superconductivity and Flux Phase in the t-J Model." Max-Planck-Institut fuer Festkoerperforschung, Heisenbergstrasse 1, D-70569 Stuttgart, GERMANY; telephone +49 711 689 1537; telefax +49 711 689 1595; e-mail emmcapp@audrey.mpi-stuttgart.mpg.de; preprint also available at cond- mat@xxx.lanl.gov (#9808201). 74.20.Mn; 74.25.Dw; 71.27.+a.

J. M. Chen, R. S. Liu, M. J. Kramer, K. W. Dennis, and R. W. McCallum, "Soft X-Ray Absorption Study of (Nd1.05-xPrx)Ba1.95Cu3O7 Using Synchrotron Radiation." To be published in Chem. Phys. Lett. Synchrotron Radiation Research Center, No. 1 R&D Road VI, Hsinchu Science-Based Industrial Park, Hsinchu 30077, Taiwan, REPUBLIC OF CHINA; telephone +886 35 78 0281; telefax +886 35 78 9816; e-mail jmchen@alpha1.srrc.gov.tw.

T. Chiba, Y.-L. Wang, R. L. Sabatini, L.-J. Wu, M. Suenaga, P. Haldar, and K. Noto, "Enhanced Critical Current in Bi2Sr2Ca2Cu3O10/Ag Tapes by a Low-Temperature Intermediate Heat Treatment." To be published in Physica C. Department of Applied Science, Brookhaven National Laboratory, Upton, NY 11973-5000.

Michele Cini, Gianluca Stefanucci, and Adalberto Balzarotti, "Pairing in the Three-Band Hubbard Model of the Cu-O Plane." Preprint #ROM2F/98/32. Dipartimento di Fisica, Istituto Nazionale di Fisica della Materia, Universita di Roma "Tor Vergata," Via della, Ricerca Scientifica, I- 00133 Rome, ITALY; e-mail michele.cini@roma2.infn.it; preprint also available at cond-mat@xxx.lanl.gov (#9808209).

J. A. Clayhold, F. Chen, J. P. McCarten, Z. H. Zhang, and A. J. Schofield, "Experimental Constraints on Models of Normal-State Transport." 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 and Astronomy, Clemson University, Clemson, SC 29634-1911. Key words: high Tc, superconductor, normal state, transport, thermopower.

T. Dahm, D. Manske, and L. Tewordt, "Collective Modes in High- Temperature Superconductors." To be published in Phys. Rev. B. Max- Planck-Institut fuer Physik komplexer Systeme, Noethnitzer Str. 38, D- 01187 Dresden, GERMANY; D. Manske's telephone in Berlin +49 30 838 3042; telefax +49 30 838 6799; e-mail dmanske@physik.fu-berlin.de; preprint also available at cond-mat@xxx.lanl.gov (#9808210). 74.20.Mn; 74.25.Ha; 74.25.Jb; 74.40.+k.

G. D'Anna, V. Berseth, L. Forro, A. Erb, and E. Walker, "Hall Anomaly and Vortex-Lattice Melting in Superconducting Single Crystal YBa2Cu3O7- d." To be published in Phys. Rev. Lett. Institut de Genie Atomique, Departement de Physique, Ecole Polytechnique Federale de Lausanne, CH- 1015 Lausanne, SWITZERLAND; e-mail danna@igahpse.epfl.ch; preprint also available at cond-mat@xxx.lanl.gov (#9808164). 74.25.Fy; 74.60.Ge; 74.72.Bk.

A. Das, S. Koishikawa, T. Fukuzaki, M. Muralidhar, and M. Murakami, "Magneto-Optical Characterization of Nd0.33Eu0.33Gd0.33Ba2Cu3O7 Superconductors." To be published in Appl. Supercond. (in press). Superconductivity Research Laboratory, Division 7, International Superconductivity Technology Center (ISTEC), 1-16-25 Shibaura, Minato- Ku, Tokyo 105, JAPAN; M. Muralidhar's telephone +81 19 635-9015 or -9016; telefax +81 19 635-9017; e-mail miryala@istec.or.jp. Key words: Nd0.33Eu0.33Gd0.33Ba2Cu3O7, magneto-optical characterization, critical state, critical current density.

M. Daeumling, S. K. Olsen, C. Rasmussen, C. Traeholt, A. Kuehle, and O. Tonnesen, "Measuring ac Losses in Superconducting Cables Using a Resonant Circuit: The Resonant Current Experiment (RESCUE)." To be published in Supercond. Sci. & Technol. NKT Research Center, Priorparken 878, DK-2605 Brondby, DENMARK.

Thorsten Droese and Cristiane de Morais Smith, "Crossover from Rigid to Elastic Vortex Creep in Thin Layered Superconductors with Columnar Defects." Submitted to Phys. Rev. B. Institut fuer Theoretische Physik, Universitaet Hamburg, Jungiusstrasse 9, D-20355 Hamburg, GERMANY; telephone +49 40 4123 2427; telefax +49 40 4123 6798; e-mail droese@physnet.uni-hamburg.de; preprint also available at cond- mat@xxx.lanl.gov (#9807278). 74.60.Ge; 64.60.My; 64.60.Qb; 74.76.Bz.

J. Fompeyrine, R. Berger, Ch. Gerber, J. Perret, J. W. Seo, and J.-P. Locquet, "Local Determination of the Terminating Layer of SrTiO3." 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). IBM Research Division, Zurich Research Laboratory, Saeumerstrasse 4, CH-8803 Rueschlikon, SWITZERLAND; e-mail jfo@zurich.ibm.com. Key words: friction force microscopy, thin oxide films, substrate preparation.

M. Franz, "Mixed-State Quasiparticle Transport in High-Tc Cuprates: Localization by Magnetic Field." Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218; e-mail franz@pha.jhu.edu; preprint also available at cond-mat@xxx.lanl.gov (#9808230).

U. Frey, M. Basset, K. UEstuener, M. Blumers, Ch. Schwan, J. C. Martinez, and H. Adrian, "Josephson Junctions and Superconducting Field Effect Transistors Based on Epitaxial Bi2Sr2Can-1CunO2(n+2) Thin Films." To be published in Appl. Supercond. (in press). Institut fuer Physik, Johannes Gutenberg-Universitaet Mainz, D-55099 Mainz, GERMANY.

M. Golosovsky, "Physical Mechanisms Causing Nonlinear Microwave Losses in High-Tc Superconductors." Presented at the 8th Workshop on rf Supercond., Abano Terme, Italy, Oct. 8, 1997; to be published in Particle Accelerators. Racah Institute of Physics, Hebrew University of Jerusalem, Jerusalem 91904, ISRAEL; telephone +972 2 658-5139 or -6551; telefax +972 2 5617 805; e-mail golos@vms.huji.ac.il. Key words: superconductivity, radiofrequency, cavities, surface impedance, thin films.

K. C. Goretta, E. T. Park, R. E. Koritala, M. M. Cuber, E. A. Pascual, Nan Chen, A. R. de Arellano-Lopez, and J. L. Routbort, "Thermomechanical Response of Polycrystalline BaZrO3." Submitted to Physica C. 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.

Tomoko Goto, Masahide Takahama, and Takuji Kimura, "OCMG Process for Filamentary Nd123 Superconductor Produced by Solution Spinning." To be published in Appl. Supercond. (in press). Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466, JAPAN.

G. Gritzner, A. Buckuliakova, G. Plesch, K. Przybylski, and M. Mair, "Preparation and Characterization of Tl-Ba-Ca-Cu-O 2212 Superconducting Thick Films." To be published in Physica C (in press). Institut fuer Chemische Technologie Anorganischer Stoffe, Johannes Kepler Universitaet, A-4040 Linz, AUSTRIA; telephone +43 732 2468 703; telefax +43 732 2468 905; e-mail gerhard.gritzner@ictas.uni-linz.ac.at. Key words: superconducting films, Tl-2212 films, microstructure.

J.-C. Grivel, H. F. Poulsen, L. G. Andersen, T. Frello, N. H. Andersen, E. Giannini, D. P. Grindatto, and R. Fluekiger, "Investigations on the Formation Mechanism of the Bi(2223) Phase in Bulk Samples and Ag-Sheated Tapes." To be published in Proc. of the 1998 Int. Workshop on Supercond.: Mater. and Technol. Issues for HTS Wires and Bulk Applications, Okinawa, Japan, July 12-15, 1998. Nordic Superconductor Technologies, Prioparken 878, DK-2605 Brondby, DENMARK; telephone +45 4348 2500; telefax +45 4348 2501; e-mail nst@nst.com.

H.-U. Habermeier, T. Haage, J. Zegenhagen, V. G. Hadjev, R. Warthmann, and Ch. Jooss, "Anisotropic Enhancement of Flux Pinning in Y-Ba-Cu-O Thin Films Grown by the Step-Flow Growth Mode." 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). Max-Planck-Institut fuer Festkoerperforschung, Heisenbergstrasse 1, D-70569 Stuttgart, GERMANY. Key words: YBCO thin films, critical current, step-flow growth, Raman scattering, fluctuation conductivity.

A. Hu, X. Obradors, V. Gomis, T. Puig, A. Carrillo, E. Cardellach, E. Mendoza, Z. X. Zhad, and J. W. Xiong, "Fabrication of Melt-Textured Nd123 Superconductors with Nd2BaO4 Addition." To be published in Appl. Supercond. (in press). Institut de Ciencia de Materials, Campus Universitat Autonoma de Barcelona, E-08193 Bellaterra, Barcelona, SPAIN.

H. Ikuta, S. Ikeda, A. Mase, M. Yoshikawa, Y. Yanagi, Y. Itoh, T. Oka, and U. Mizutani, "Melt-Processing of Ag-Added LRE-Ba-Cu-O (LRE=Nd,Sm)." To be published in Appl. Supercond. (in press). Center for Integrated Research in Science and Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8603, JAPAN; telephone +81 52 789 4462; telefax +81 52 789 5317; e-mail ikuta@nuap.nagoya-u.ac.jp.

H. Ikuta, A. Mase, Y. Yanagi, M. Yoshikawa, Y. Itoh, T. Oka, and U. Mizutani, "Melt-Processed Sm-Ba-Cu-O Superconductors Trapping Strong Magnetic Field." To be published in Supercond. Sci. & Technol. Center for Integrated Research in Science and Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8603, JAPAN; telephone +81 52 789 4462; telefax +81 52 789 5317; e-mail ikuta@nuap.nagoya-u.ac.jp. 74.60.Ge; 74.72.Bk; 74.80.Bj.

M. N. Iliev, H. G. Lee, A. P. Litvinchuk, Z. L. Du, Y. S. Wang, and C. W. Chu, "Correlation Between Tc and Oxygen Arrangement of the Charge Reservoir Block in (Cu,C)Ba2Ca2Cu3O9-d: A Raman Study." Preprint #98:071; submitted to Phys. Rev. B. 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. 78.30.-j; 74.25.Kc; 74.72.Jt; 74.62.Dh.

Mohan V. Jacob, Janina Mazierska, Jeha Kim, Kwang-Yong Kang, and G. P. Srivastava, "Microwave and Microstructure Studies of Silver Doped YBa2Cu3O7-d Thin Films." To be published in Supercond. Sci. & Technol. Electrical and Computer Engineering, School of Engineering, James Cook University, Townsville, QLD-4811, AUSTRALIA; telephone +61 7 4781 4867; telefax +61 7 4725 1348; e-mail mohan.jacob@jcu.edu.au.

Boldizsar Janko, Ioan Kosztin, K. Levin, M. R. Norman, and Douglas J. Scalapino, "Incoherent Pair Tunneling as a Probe of the Cuprate Pseudogap." Submitted to Phys. Rev. Lett. James Franck Institute, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637; e- mail janko@rainbow.uchicago.edu; preprint also available at cond- mat@xxx.lanl.gov (#9808215). 74.50.+r; 74.40.+k; 74.20.Mn; 74.72.-h.

G. Johansson, E. N. Bratus, V. S. Shumeiko, and G. Wendin, "Resonant Multiple Andreev Reflections in Mesoscopic Superconducting Junctions." Department of Microelectronics and Nanoscience, 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 (#9807240).

Giancarlo Jug and Boris N. Shalaev, "Low-Temperature Renormalization Group Study of Uniformly Frustrated Models for Type-II Superconductors." To be published in Phys. Rev. B. Max-Planck Institut fuer Physik Komplexer Systeme, Aussenstelle Stuttgart, Heisenbergstr. 1, Postfach 800665, D-70569 Stuttgart, GERMANY; e-mail jug@mpipks-dresden.mpg.de; preprint also available at cond-mat@xxx.lanl.gov (#9808125). 74.60.Ge; 74.60.Ec.

J. Jung, H. Yan, H. Darhmaoui, and W.-K. Kwok, "Universal Transport and Magnetic Properties of YBCO and TBCCO 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 Alberta, Edmonton, Alberta, CANADA T6G 2J1. Key words: Josephson nanostructures, critical current, vortex pinning, high-temperature superconductors.

A. B. Kaiser and G. C. McIntosh, "Thermoelectic Power of Cuprates and Other Superconductors." 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, Victoria University of Wellington, P.O. Box 600, Wellington, NEW ZEALAND; e-mail alan.kaiser@vuw.ac.nz. Key words: superconductors, cuprates, thermopower, transport, Van Hove scenario, electron-phonon interaction.

Beom Jun Kim and Petter Minnhagen, "Giant Shapiro Steps for Two- Dimensional Josephson Junction Arrays with Time-Dependent Ginzburg- Landau Dynamics." Submitted to Phys. Rev. B. Department of Theoretical Physics, Umea University, 901 87 Umea, SWEDEN; e-mail kim@tp.umu.se; preprint also available at cond-mat@xxx.lanl.gov (#9808128). 74.50.+r; 74.40.+k; 74.60.Ge; 74.60.Jg.

Chan-Joong Kim, Young A. Jee, Kyu-Won Lee, Tae-Hyun Sung, Sang-Chul Han, Il-Hyun Kuk, and Gye-Won Hong, "Low Temperature Melt Process of SmBa2Cu3O7-y Using a Liquid Infiltration Technique." To be published in Appl. Supercond. (in press). Superconductivity Research Laboratory, Korea Atomic Energy Research Institute, P.O. Box 105, Yusung, Taejon 305-600, KOREA.

Nam Kim, Yong Joo Doh, Hyun-Sik Chang, and Hu-Jong Lee, "Suppressed Superconductivity of the Surface Conduction Layer in Bi2Sr2CaCu2O8+x Single Crystals Probed by c-Axis Tunneling Measurements." Department of Physics, Pohang University of Science and Technology, Pohang 790-784, SOUTH KOREA; e-mail hjlee@vision.postech.ac.kr; preprint also available at cond-mat@xxx.lanl.gov (#9808102).

M. R. Koblischka, T. Higuchi, S. I. Yoo, M. Murakami, T. Frello, M. Baziljevich, T. H. Johansen, T. Wolf, and P. Diko, "Magnetic Measurements in NdBa2Cu3O7-d Single Crystals: Magnetization, Flux Pinning and Creep." To be published in Appl. Supercond. (in press). Superconductivity Research Laboratory, International Superconductivity Technology Center (ISTEC), 1-16-25 Shibaura, Minato-ku, Tokyo 105, JAPAN. 74.60.Ec; 74.60.Ge; 74.60.Jg.

M. R. Koblischka, M. Muralidhar, and M. Murakami, "Flux Pinning in Ternary (Nd0.33Eu0.33Gd0.33)Ba2Cu3Oy Melt-Processed Superconductors." To be published in Appl. Phys. Lett. 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.

Yijie Li, Xin Yao, and K. Tanabe, "Laser-Ablation-Induced Surface Modification of NdBa2Cu3O7-d Single Crystal Target in Pulsed Laser Deposition." To be published in J. Appl. Phys. Superconductivity Research Laboratory, International Superconductivity Technology Center (ISTEC), 10-13 Shinonome 1-chome, Koto-ku, Tokyo 135, JAPAN; telephone +81 3 3536 5709; telefax +81 3 3536 5717; e-mail yjli@istec.or.jp. 42.62.-b; 61.80.Ba; 81.15.Fg; 81.65.Ya.

M. Lindgren, M. Currie, Wen-Sheng Zeng, R. Sobolewski, and S. Chereonichenko, "Picosecond Response of a Superconducting Hot-Electron NbN Photodetector." To be published in Appl. Supercond. (in press). Contact R. Sobolewski, Department of Electrical and Computer Engineering and Laboratory for Laser Energetics, University of Rochester, P.O. Box 270231, Rochester, NY 14627-0231.

F. Lombardi, Z. G. Ivanov, P. Komissinski, G. M. Fischer, P. Larsson, and T. Claeson, "The Influence of the Top and the Bottom Grain Boundaries on the Current Transport in YBCO Step-Edge Josephson Junction." To be published in Appl. Supercond. (in press). Department of Physics, Chalmers University of Technology and Goeteborg University, S-41296 Goeteborg, SWEDEN.

Massimo Marezio, Francesca Licci, and Andrea Gauzzi, "On the Strategies for Increasing the Critical Temperature of Superconductors." 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). MASPEC-Consiglio Nazionale delle Ricerche, Via Chiavari 18/A, I-43100 Parma, ITALY. Key words: superconducting materials, strategies for the search of new materials, Sr substitution in YBCO.

N. Markovic, C. Christiansen, and A. M. Goldman, "Thickness-Magnetic Field Phase Diagram at the Superconductor-Insulator Transition in 2D." Submitted to Phys. Rev. Lett. School of Physics and Astronomy, University of Minnesota, 116 Church St. S.E., Minneapolis, MN 55455; telephone (612) 624-9366; telefax (612) 624-4578; e-mail nmarkovic@physics.spa.umn.edu; preprint also available at cond- mat@xxx.lanl.gov (#9808176). 74.76.-w; 74.40.+k; 74.25.Dw; 72.15.Rn.

F. Marti, G. Grasso, Y. B. Huang, and R. Fluekiger, "Progress in Critical Current Density of Long Bi(2223) Tapes Deformed by Periodic Pressing." Submitted to Supercond. Sci. & Tech. Departement de Physique de la Matiere Condensee, Universite de Geneve, 24 quai Ernest- Ansermet, CH-1211 Geneva 4, SWITZERLAND; telephone +41 22 702 6078; telefax +41 22 702 6869; e-mail frank.marti@sc2a.unige.ch.

Vladimir C. Matijasevic and Per Slycke, "Reactive Evaporation Technology for Fabrication of YBCO Wafers for Microwave Applications." 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). Conductus, Inc., 969 West Maude Avenue, Sunnyvale, CA 94086. Key words: superconductors, thin films, YBCO, rate monitor, tunable-diode laser.

S. Menkel, D. Drung, C. Assmann, and T. Schurig, "A Resistive dc SQUID Noise Thermometer." To be published in Appl. Supercond. (in press). Physikalisch-Technische Bundesanstalt, Abbestr. 10-12, D-10587 Berlin, GERMANY.

O. V. Misochko and S. Uchida, "Low Energy Raman Continua of La2- xSrxCu2O4 High-Tc Superconductors: Polarization, Doping, and Temperature Dependencies." To be published in Phys. Lett. A. Institute of Solid State Physics, Russian Academy of Sciences, 142432 Chernogolovka, Moscow Region, RUSSIA; e-mail misochko@issp.ac.ru. Key words: Raman scattering, high-Tc superconductivity, order parameter, doping dependence. 74.25.Gz; 74.62.Dh; 74.72.Dn.

S. Miura, K. Hashimoto, T. Inoue, K. Muranaka, J. G. Wen, K. Suzuki, Y. Enomoto, and T. Morishita, "Electrical Properties of Y1Ba2Cu3Ox Films Grown by Liquid Phase Epitaxy." To be published in Appl. Supercond. (in press). Superconductivity Research Laboratory, International Superconductivity Technology Center (ISTEC), 10-13 Shinonome 1-chome, Koto-ku, Tokyo 135, JAPAN; telephone +81 3 3536-5703 through -5705; telefax +81 3 3536-5714 or -5717.

Yoshinao Mizugaki and Koji Nakajima, "Numerical Simulation for Digital Applications of a Coupled-SQUID Gate with dc Biasing." To be published in Appl. Supercond. (in press). Laboratory for Electronic Intelligent Systems, Research Institute of Electrical Communication, Tohoku University, Sendai 980-77, JAPAN.

U. Mizutani, T. Oka, Y. Itoh, Y. Yanagi, M. Yoshikawa, and H. Ikuta, "Pulsed-Field Magnetization Applied to High-Tc Superconductors." To be published in Appl. Supercond. (in press). Department of Crystalline Materials Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464- 0814, JAPAN; telefax +81 52 789 3821.

T. Mochida, N. Chikumoto, and M. Murakami, "Effect of Nd4Ba2Cu2O10 Addition on the Pinning Properties of Nd-Ba-Cu-O Crystals." To be published in Appl. Supercond. (in press). Superconductivity Research Laboratory, International Superconductivity Technology Center (ISTEC), 1-16-25 Shibaura, Minato-ku, Tokyo 105, JAPAN. Key words: Nd-Ba-Cu-O, critical current density, peak effect, Nd4Ba2Cu2O10, flux creep.

Victor V. Moshchalkov, Lieven Trappeniers, Johan Vanacken, and Yvan Bruynseraede, "Scaling Behavior of the Normal State Properties of the Underdoped High-Tc Cuprates." 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). Laboratorium voor Vaste-Stoffysica en Magnetisme, Katholieke Universiteit Leuven, Celestijnenlaan 200 D, B-3001 Leuven, BELGIUM. Key words: copper oxides, quantized spin models, transport properties, charge stripes.

M. Murakami, "Key Issues for the Characterization of RE-Ba-Cu-O Systems (RE:Nd,Sm,Eu,Gd)." To be published in Appl. Supercond. (in press). Superconductivity Research Laboratory, International Superconductivity Technology Center (ISTEC), 16-25 Shibaura 1-chome, Minato-ku, Tokyo 105- 0023, JAPAN; e-mail murakami@istec.or.jp.

Shuichi Nagasawa, Hideaki Numata, Yoshihito Hashimoto, and Shuichi Tahara, "1 GHz Clock Operation of Josephson Rams." To be published in Appl. Supercond. (in press). Fundamental Research Laboratories, NEC Corporation, 34 Miyukigaoka, Tsukuba 305-8501, JAPAN.

A. K. Nguyen and A. Sudbo, "A New Broken U(1)-Symmetry in Extreme Type- II Superconductors." Department of Physics, Norwegian University of Science and Technology, N-7034 Trondheim, NORWAY. 74.20.De; 74.25.Dw; 74.25.Ha; 74.60.Ec.

Gunadhor S. Okram, Haruyoshi Aoki, and Keikichi Nakamura, "Negative Curvature of Upper Critical Fields and Dimensional Crossover in YBa2Cu3O7-d Thin Films." Submitted to Phys. Rev. Lett. Tsukuba Magnet Laboratory, National Research Institute for Metals, 3-13 Sakura, Tsukuba, Ibaraki 305, JAPAN; telephone +81 298 59 5092; telefax +81 298 59 5010; e-mail okram@nrim.go.jp. 74.72.Bk; 74.76.Bz; 74.60.Ec; 74.25.Fy.

Leonid A. Openov, "Critical Temperature of an Anisotropic Superconductor Containing both Nonmagnetic and Magnetic Impurities." To be published in Phys. Rev. B. Moscow State Engineering Physics Institute, Technical University, 115409 Moscow, RUSSIA; e-mail opn@supercon.mephi.ru. 74.20.-z; 74.62.Dh.

E. Orignac and T. Giamarchi, "Anderson Localization in Hubbard Ladders." To be published in Physica B: Proc. of the Int. Conf. on Strongly Correlated Electron Systems (SCES98), Paris, France, July 15-18, 1998. Laboratoire de Physique des Solides, Universite Paris-Sud, Bat. 510, F- 91405 Orsay, FRANCE; e-mail orignac@lps.u-psud.fr; preprint also available at cond-mat@xxx.lanl.gov (#9808015).

M. S. Osofsky, R. J. Soulen, Jr., J. M. Byers, B. F. Woodfield, D. B. Chrisey, J. S. Horwitz, and R.C.Y. Auyeung, "Spin-Injection into Superconductors." 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). Naval Research Laboratory, Washington, DC 20375. Key words: non-equilibrium superconductivity, spin polarization, spin injection.

Y. Paltiel, D. T. Fuchs, E. Zeldov, Y. N. Myasoedov, H. Shtrikman, M. L. Rappaport, and E. Y. Andrei, "Surface Barrier Dominated Transport in NbSe2." Submitted to Phys. Rev. B. Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot 76100, ISRAEL; telephone +972 8 934-3667 or -3101; telefax +972 8 934-4128; e-mail hpalt@wis.weizmann.ac.il; preprint also available at cond- mat@xxx.lanl.gov (#9808218). 74.60.Ec; 74.60.Ge; 74.60.Jg.

G. Preosti, Y. M. Vilk, and M. R. Norman, "Evolution of the Pairing Pseudogap in the Spectral Function with Interplane Anisotropy." Submitted to Phys. Rev. B. Materials Science Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439; e-mail preosti@hexi.msd.anl.gov; preprint also available at cond- mat@xxx.lanl.gov (#9808298).

Mladen Prester, P. Kovac, and I. Husek, "Initial Dissipation and Finite Size Effect in Inhomogeneous Superconductors: The Case of BPSCCO/Ag Tapes." 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). Institute of Physics, University of Zagreb, P.O.B. 304, HR-10 000 Zagreb, CROATIA. Key words: Josephson networks, high-Tc superconductors, weak-link networks, percolation, size effect, finite-size scaling, fractal growth, non-Ohmic dissipation, critical phenomena, criticial currents, scaling exponents.

R. Provoost, K. Rosseel, D. Dierickx, R. E. Silverans, V. V. Moshchalkov, H. Kojo, and M. Murakami, "Stress Analysis in Melt Processed RBa2Cu3O7 (R=Y,Nd) by Micro-Raman Spectroscopy." To be published in Appl. Supercond. (in press). Laboratorium voor Vaste Stoffysica en Magnetisme, Katholieke Universiteit Leuven, Celestijnenlaan 200D, B-3001 Leuven, BELGIUM.

Y. Radzyner, Y. Abulafia, Y. Yeshurun, T. Staiger, and G. Fuchs, "Local Magnetization Measurements on Bi2Sr2Ca2Cu3O10 Tapes." To be published in Physica C. Department of Physics, Institute for Superconductivity, Bar-Ilan University, Ramat-Gan 52900, ISRAEL; telephone +972 3 531 8607; telefax +972 3 535 3298; e-mail radzyner@mail.biu.ac.il. Key words: weak links, critical current density, local measurements, magnetic measurements, granular material, flux creep. 74.72.Hs; 74.80.Bj; 74.60.Jg; 74.60.Ge.

R. Robertz, H. Bougrine, A. Rulmont, M. Ausloos, and R. Cloots, "Synthesis of High Quality Bi-Based 2223 Materials on BaZrO3 Substrates by the Glassy Matrix Method." Presented at the 9th World Ceramic Congress and Forum on New Mater. (CIMTEC'98), Florence, Italy, June 14- 19, 1998. SUPRAS, Chemistry Institute B6, University of Liege, Sart- Tilman, B-4000 Liege, BELGIUM.

N. L. Saini, A. Lanzara, A. Bianconi, J. Avila, M. C. Asensio, S. Tajima, G. D. Gu, and N. Koshizuka, "Fermi Surface Features and Charge Segregation in Bi2212 Superconductor." 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). Dipartimento di Fisica, Universita di Roma 'La Sapienza', P. Aldo Moro 2, I-00185 Roma, ITALY. Key words: high-Tc superconductivity, Fermi surface, energy distribution curves, charge segregation in stripes, pseudogap and shadow bands.

S. Sakai, S. Migita, H. Ota, H. Fujino, Y. Kasai, T. Oohira, H. Matsuhata, and K. Kajimura, "Molecular Beam Epitaxial Growth of BSCCO and Bi-Based Oxides: Self-Limiting Growth of the Bi Element." 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). Electrotechnical Laboratory, 1-1-4 Umezono, Tsukuba-shi, Ibaraki 305, JAPAN; telefax +81 298 54 5476; e-mail ssakai@etl.go.jp. Key words: molecular beam epitaxy, BiSrCaCuO, Bi4Ti3O12, thin film, self-limiting growth.

M. I. Salkola and J. R. Schrieffer, "Topological Excitations of One- Dimensional Correlated Electron Systems." Department of Physics, Stanford University, Stanford, CA 94305; telephone (650) 725-1311; telefax (650) 723-9389; e-mail msa@quantum.stanford.edu; preprint also available at cond-mat@xxx.lanl.gov (#9808205).

Olivier Schneegans, Pascal Chretien, Eleonor Caristan, Frederic Houze, Annick Degardin, and Alain Kreisler, "First Observations of YBaCuO Thin Films by Atomic Force Microscopy with Conducting Tips." 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). Laboratoire de Genie Electrique de Paris, Universites Paris 6 et Paris 11, URA 127 CNRS, SUPELEC, Plateau de Moulon, F-91192 Gif Sur Yvette Cedex, FRANCE. Key words: atomic force microscopy, conducting tip, local resistance measurements, YBaCuO grain growth, thin films, substrates.

J. Siejka, J. Garcia-Lopez, and Yves Lemaitre, "Mechanism of Oxygenation of YBaCuO Thin Films During In Situ Growth in Presence of Oxygen Plasma: Correlation Between Oxygenation and Physical Properties." 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). Groupe de Physique des Solides des Universites Paris 7 et Paris 6, URA 17 du CNRS, Tour 23, 2 Place Jussieu, F-75251 Paris, FRANCE; e-mail siejka@gps.jussieu.fr. Key words: YBaCuO, NRA, atomic oxygen, oxidation, R_s properties.

V. Sokolovsky, V. Meerovich, S. Goren, and G. Jung, "Analytical Approach to ac Loss Calculation in High-Tc Superconductors." To be published in Physica C (in press). Department of Physics, Ben-Gurion University of the Negev, P.O. Box 653, 84105 Beer-Sheva, ISRAEL; telephone +972 7 647 2458; telefax +972 7 647 2903; e-mail victorm@bgumail.bgu.ac.il. Key words: critical state model, ac losses, superconductor.

V. F. Solovyov, H. J. Wiesmann, M. Suenaga, and R. Feenstra, "Thick YBa2Cu3O7 Films by Post Annealing of the Precursor by High Rate e-Beam Deposition on SrTiO3 Substrates." To be published in Physica C. Department of Applied Science, Brookhaven National Laboratory, Upton, NY 11973.

O. M. Stoll, S. Kaiser, R. P. Huebener, and M. Naito, "Intrinsic Flux- Flow Resistance Steps in the Cuprate Superconductor Nd2-xCexCuOy." To be published in Phys. Rev. Lett. Physikalisches Institut, Lehrstuhl fuer Experimentalphysik II, Universitaet Tuebingen, Morgenstelle 14, D- 72076 Tuebingen, GERMANY; telephone +49 7071 2976318; telefax +49 7071 295406. 74.25.Fy; 74.60.Ge; 74.72.Jt.

Gernot Stollhoff, "Electrons in High-Tc Compounds: Ab-Initio Correlation Results." To be published in Phys. Rev. B. Max-Planck- Institut fuer Festkoerperforschung, Heisenbergstrasse 1, D-70569 Stuttgart, GERMANY; e-mail stolh@audrey.mpi-stuttgart.mpg.de; preprint also available at cond-mat@xxx.lanl.gov (#9808127). 74.72.-h; 71.45.Gm; 71.15.-m; 75.10.Lp; 75.25.+z; 31.15.Dv; 31.25.Eb.

Xuefeng Sun, Xia Zhao, Wenbin Wu, Xiaojuan Fan, and Xiao-Guang Li, "Growth of Bi2Sr2Ca1-xPrxCu2Oy Single Crystals from Bi-Rich Melts." To be published in Physica C (in press). Department of Materials Science and Engineering, University of Science and Technology of China, Academia Sinica, Hefei 230026, PEOPLE'S REPUBLIC OF CHINA; e-mail xfsun@dmse.mse.ustc.edu.cn. Key words: Pr-doped, Bi-based, crystal growth.

Xuefeng Sun, Xia Zhao, Wenbin Wu, Xiaojuan Fan, Xiao-Guang Li, and H. C. Ku, "Pr-Doping Effect on the Structure and Superconductivity of Bi2Sr2Ca1-xPrxCu2Oy Single Crystals." To be published in Physica C. Department of Materials Science and Engineering, University of Science and Technology of China, Academia Sinica, Hefei 230026, PEOPLE'S REPUBLIC OF CHINA; e-mail xfsun@dmse.mse.ustc.edu.cn. Key words: Bi2Sr2Ca1-xPrxCu2Oy, single crystals, structure, superconductivity.

Ashfaq S. Thanawalla, S. K. Dutta, C. P. Vlahacos, D. E. Steinhauer, B. J. Feenstra, Steven M. Anlage, F. C. Wellstood, and Robert B. Hammond, "Microwave Near-Field Imaging of Electric Fields in a Superconductor Microstrip Resonator." Preprint #CSR-980519-1; submitted to Appl. Phys. Lett. Department of Physics, Center for Superconductivity Research, University of Maryland, College Park, MD 20742-4111; B. J. Feenstra's telephone (301) 405-6132; telefax (301) 314-9541; e-mail feenstra@squid.umd.edu; preprint also available at cond-mat@xxx.lanl.gov (#9805239). 85.25.Am; 74.25.Nf; 07.79.-v.

J. M. Tranquada, "Phase Separation, Charge Segregation, and Superconductivity in Layered Cuprates." Preprint #BNL-65377; to be published in Neutron Scattering in Layered Copper-Oxide Superconductors, edited by A. Furrer (Kluwer, Dordrecht, The Netherlands). Department of Physics, Brookhaven National Laboratory, Upton, NY 11973; e-mail jtran@bnl.gov.

P.A.W. van der Heide and J. W. Rabalais, "Photoelectron Spectroscopic Study of the Temperature Dependent Termination of the LaAlO3 (100) Surface." Preprint #98:068; submitted to Chem. Phys. Lett. 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.

Felix Vidal, Carolina Torron, Manuel V. Ramallo, and Jesus Mosqueira, "Magnetization Experiments on the Thermal Fluctuations of Vortices and Cooper Pairs in Multilayered Superconducting Cuprates: How Strongly Coupled Are the Pancake Vortices of the Closest Layers?" 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). Laboratorio de Bajas Temperaturas y Superconductividad, Facultad de Fisica, Universidad de Santiago de Compostela, E-15706 Santiago de Compostela, SPAIN. Key words: multilayered superconductors, magnetization of high-Tc superconductors, vortex and Cooper-pairs thermal fluctuations, thickness of the vortex pancakes.

John K. F. Yau, Nick Savvides, and C. C. Sorrell, "High-Tc Superconducting Current Leads." To be published in Physica C. Department of Physics, Chinese University of Hong Kong, Shatin, N.T., HONG KONG; telephone +852 2609 6278; telefax +852 2603 5204. Key words: current leads, fabrication, critical current, uniformity, field dependence.

S.-K. Yip, "Energy Resolved Supercurrent Between Two Superconductors." To be published in Phys. Rev. B. Department of Physics & Astronomy, Northwestern University, Evanston, IL 60208; e-mail yip@snowmass.phys.nwu.edu; preprint also available at cond- mat@xxx.lanl.gov (#9808115). 74.80.Fp; 74.50.+r.

Xia Zhao, Xuefeng Sun, Xiaojuan Fan, Wenbin Wu, Xiao-Guang Li, Shuquan Guo, and Zhongxian Zhao, "Correlation Between Tc and n_s/m* in Bi2Sr2CaCu2O8+d Single Crystals." To be published in Physica C. Department of Materials Science and Engineering, University of Science and Technology of China, Academia Sinica, Hefei 230026, PEOPLE'S REPUBLIC OF CHINA; Xuefeng Sun's e-mail xfsun@dmse.mse.ustc.edu.cn. Key words: penetration depth, n_s/m*.

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

*Nov. 16 - 19, 1998: 11th International Symposium on Superconductivity (ISS'98), Fukuoka Sunpalace Hotel, Fukuoka, Japan. Organized by the International Superconductivity Technology Center (ISTEC). Symposium will consist of oral and poster sessions and invited talks in the following topics: Physics -- theory, physical properties, and new measurement techniques; Chemistry -- new materials and syntheses, substitution, solid-state chemistry, and properties; Critical Current -- flux-pinning mechanism, vortex physics, and weak links; Wires, Tapes, and Bulk -- solid-state powder ceramics, chemical-solution processing, melting solidification, and chemical-vapor deposition; Films and Junctions -- processing, properties, lithography, junction fabrication, and physics; Device Applications -- digital, analog, SQUID, and other electronic devices; System Applications -- power, power transportation, magnets, magnetic shields, and other system applications; Standardization -- standardization for electromagnetic, mechanical, and microwave properties measurements. Will also include exhibition of materials and devices. Proceedings to be published. Official language is English. For further information, contact ISS'98 Secretariat, ISTEC, Eishin Kaihatsu Bldg. 6F, 34-3 Shimbashi 5-chome, Minato-ku, Tokyo 105- 0004, Japan; telephone +81 3 3431 4002; telefax +81 3 3431 4044.

*May 30 - June 3, 1999: 10th International Symposium on Intercalation Compounds (ISIC 10), Okazaki, Japan. Tenth in the series. Will focus on basic ideas in both the physics and chemistry of intercalation materials such as graphite, fullerenes, carbon nanotubes, chalcogenides, oxides, clays, zeolites, and other related materials. Topics to be covered: new intercalation compounds and new synthetic routes; thermodynamics, kinetics, and reaction mechanisms; structure and lattice dynamics; phase transitions; electronic properties, charge transfer, and band structures; transport properties and superconductivity; magnetic properties; electrochemical properties; intercalation electrodes for advanced batteries; and other present and potential applications. Scientific program will consist of plenary lectures as well as oral and poster sessions. Proceedings to be published as a special issue of Molecular Crystals and Liquid Crystals. Abstract deadline, December 15, 1998. For further information, contact Toshiaki Enoki, ISIC 10, Department of Chemistry, Tokyo Institute of Technology, Ookayama, Meguro-ku, Tokyo 152-8551, Japan; telefax +81 3 5734 2242; e-mail isic@chem.titech.ac.jp; Web site http://www.chem.titech.ac.jp/~isic/.

July 7 - 10, 1999: Ninth International Workshop on Critical Currents (IWCC9-99), University of Wisconsin, Madison, Wisconsin. 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 10, 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 madams@engr.wisc.edu.

July 30 - Aug. 3, 1999: LOCALIZATION 1999 -- Disorder and Interaction in Transport Phenomena, Hamburg, Germany. Satellite to the LT-22 Conference in Helsinki, Finland (Aug. 4-11, 1999). Covers the physics of transport phenomena in the presence of disorder, chaos, and interactions, in particular concentrating on weak localization, hopping transport, metal-insulator transitions, non-Fermi liquid behavior, many- particle localization, disorder and superconductivity, superconductor- insulator transitions, disorder and magnetism, quantum transport in nanostructures, quantum Hall effects, topological disorder, quantum percolation, disorder and quantum chaos, classical wave localization, coherence and dephasing, and dirty bosons. For further information contact Bernhard Kramer, Institute for Theoretical Physics, Jungiusstr. 9, University of Hamburg, D-20355 Hamburg, Germany; telephone +49 40 4123-4997 or -2408; telefax +49 40 4123-4997 or -6798; e-mail kramer@physnet.uni-hamburg.de.

*Aug. 12 - 15, 1999: Electron Transport in Mesoscopic Systems, Chalmers University of Technology and Goeteborg University, Goeteborg Sweden. Satellite to the LT-22 Conference in Helsinki, Finland (Aug. 4-11, 1999). The five main topics are: single charge tunneling, Andreev reflections and proximity effects in S/N structures, transport in quantum dots and wires, time-dependent transport in mesoscopic structures, and superconducting nano-circuits. Format is expected to be two sessions for each main topic with a rapporteur starting the first session (giving an introduction to the topic, the recent progress in the field, and the outstanding problems to be solved with possible projections) and a regular invited speaker starting the other one. Three additional oral contributions and time for extended discussions planned. Attendance limited to about 200 persons. For information, contact Tord Claeson, Conference Chair, Department of Physics, Chalmers University of Technology, S-41296 Goeteborg, Sweden; e-mail f4atc@fy.chalmers.se.

*Sept. 14 - 17, 1999: Fourth European Conference on Applied Superconductivity (EUCAS'99), Melia Gran Sitges, Hotel in Sitges, Barcelona, Catalonia, Spain. Aim is to provide a forum for presentation and discussion of the developments in the field of the applications of superconductivity, in both large and small scale, including the most recent advances in the subject. All aspects of applied superconductivity will be covered, from both a scientific point of view (which include contributions from the fields of physics, electronics, material properties, chemistry, and engineering), and also an industrial perspective. Conference will encourage new cooperation on European and wider international levels. The program will be divided into two main sections. Large Scale & Power Applications will include fusion and SMES, detectors and accelerators, fault current limiters, motors and generators, high magnetic fields, wires and cables, materials related to large-scale applications, system aspects, and other applications. Small Scale & Electronic Applications will include Josephson Junctions, SQUIDs, digital applications, mixers/detectors, passive devices, oscillators and volt standards, materials related to superconducting electronics, system aspects, and other applications. Abstract deadline, March 15, 1999. For further information, contact Xavier Obradors, Institut de Ciencia de Materials de Barcelona (ICMAB-CSIC), Campus de la UAB, E-08193 Bellaterra (Barcelona), Catalonia, Spain; telephone +34 93 580 18 53; telefax +34 93 580 57 29; e-mail eucas99@icmab.es; Web site http://www.icmab.es/eucas99.

RESOURCES

Information

Proceedings: Lectures on the Physics of Highly Correlated Electron Systems: Proceedings of the Second Training Course in the Physics of Correlated Electron Systems and High-Tc Superconductors, Vietri sul Mare, Salerno, Italy (Oct. 13-25, 1997), edited by Ferdinando Mancini. This proceedings volume is not a collection of articles, but a book consisting of three chapters, covering the lectures of three well-known researchers on dissipative quantum systems (the orthogonality catastrophe, the Kondo model, macroscopic quantum phenomena, and Coulomb blockade); d-wave superconductivity (impurity scattering, post WHH theory of H_[c2], Abrikosov's vortex lattice, extended GL equation and stability of the square lattice, quasiparticle spectrum around a single vortex, YBCO and d+s wave model); and numerical techniques (Monte Carlo and quantum Monte Carlo techniques, Lanczos method, high-Tc cuprates, Hubbard model, and colossal magnetoresistance in manganites). Readership: postdoc-level individuals in highly correlated electron systems and graduate students in superconductivity. Publ. 1998; 208 pp.; price $62; ISBN 1-56396-789-8. For information, contact Springer- Verlag New York, P.O. Box 2485, Secaucus, NJ 07096; telephone (800) SPRINGER (777-4643); telefax (201) 348-4505. For orders outside U.S. and Canada, contact Springer-Verlag Berlin, P.O. Box 31 13 40, D-10643 Berlin, Germany; telephone +49 30 82787 0; telefax +49 30 82787 301; e- mail orders@springer.de.

Products and Services

A wide range of cryogenic equipment for spectroscopy applications are available from Oxford Instruments, including Raman, photoluminescence, UV/vis/IR spectroscopy; ESR and NMR; x-ray diffraction, Mossbauer, neutron and muon scattering; and resistivity, conductivity, Hall Effect, and UHV studies. For information, contact Oxford Instruments, Research Instruments, Tubney Woods, Abingdon, Oxon, OX13 5QX, United Kingdom; telephone +44 1865 393200; telefax +44 1865 393333; e-mail ssgm1.ri@oxinst.co.uk; Web site http://www.oxford-instruments.com.

FYI (High-Tc Update takes no responsibility for want ads listed in this section.)

Position Open: A postdoctoral (or visiting faculty) position is available in experimental condensed matter/material physics at the Department of Physics & Astronomy beginning September 1998. Work involves electrical and magnetic characterization of magnetic multilayers and tunnel junctions of high-temperature superconducting materials. A Ph.D. in condensed-matter physics or related area and a working knowledge of SQUID magnetometry and ac susceptometry techniques are required. Please submit a letter of application, resume and a list of three references with phone numbers and e-mail addresses to Lowell E. Wenger, Department of Physics & Astronomy, Wayne State University, Detroit, MI 48202; e-mail lwenger@sun.science.wayne.edu.

Postdoctoral positions are available in the area of condensed-matter theory at the International Centre for Theoretical Physics (ICTP) for the 1999-2000 academic year. Current research areas include strongly correlated electron systems, disordered and mesoscopic systems, ab- initio electronic structure studies, quantum liquids and solids, surface physics, statistical physics, and complex systems. Appointments will be made for one year, with the possibility of renewal for a second year. Application deadline, December 31, 1998. Send application, including detailed curriculum vitae, list of publications, and letters of recommendation to Condensed Matter Secretary, ICTP, P.O. Box 586, I- 34100 Trieste, Italy; telephone +39 040 2240347; telefax +39 040 224163; e-mail buranell@ictp.trieste.it.

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. 12, #18, Sept. 15, 1998.