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, NSF, and other agencies, organizations, and individuals.

The High-Tc Update web page is located at the URL http://www.iitap.iastate.edu/htcu/htcu.html

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:

Pseudogap

A preprint by V. V. Moshchalkov (Leuven) argues that the scaling behavior of the normal-state resistivity and the Knight shift in underdoped high-Tc cuprates can be explained in terms of a crossover at T ~ T* from a low-temperature, spin-ladder regime to a high-temperature, two-dimensional (2D) Heisenberg regime. In this picture, for T < T*, stripe formation results in quantum one-dimensional (1D) transport, with the characteristic inelastic length L_[phi] being fully controlled by the magnetic correlation length xi_m of the even-chain spin ladder, whereas for T > T*, the 2D quantum transport is governed by two- dimensional Heisenberg correlations, for which L_[phi] ~~ xi_m proportional to exp(J/T). The author asserts that the pseudogap found in underdoped (p < p_[opt]) high-Tc superconductors corresponds to the spin gap Delta(p) in even-chain 1D spin ladders.

The temperature dependence of the resistivity rho(T) of the ladder compound Sr2.5Ca11.5Cu24O41 under hydrostatic pressure of up to 8 GPa is explained by V. V. Moshchalkov et al. (Leuven) by assuming that the relevant length scale for electrical transport is given by the magnetic correlation length related to the opening of a spin gap in a 1D even- chain spin ladder. The authors extract the pressure dependence of the gap by applying this model to rho(T) data obtained at different pressures. The rho(T) dependence of the underdoped cuprate YBa2Cu4O8 scales like that of Sr2.5Ca11.5Cu24O41, which suggests that the pseudogap below T* in underdoped YBa2Cu4O8 and other high-Tc cuprates is simply the spin gap of the even-chain 1D spin ladders (stripes) formed in these materials at T < T*.

Vortices

A scanning Hall-probe microscope has been used by A. Oral (Bath) et al. to directly observe the vortex-lattice melting transition in Bi2Sr2CaCu2O8+d (Bi-2212) single crystals. The authors found that below the melting line the system settles into a fairly well ordered vortex solid, which undergoes pronounced rotations as the field is increased because of incommensurability effects. Vortex contrast is abruptly and discontinuously lost at the melting line, consistent with a first-order transition. The vortex profiles appear to be strongly broadened by two- dimensional fluctuations, which grow much stronger as the melting line is approached from below, suggesting that melting and decoupling are almost simultaneous.

A preprint by T. Matsushita (Kyushu Institute of Technology) et al. reports measurements of the force-displacement characteristics of vortex lines in an overdoped Bi-2212 single crystal using the Campbell method in the vicinity of the peak effect. The results revealed two quasistable states with different critical current densities, suggesting a phase transition of first order. Although the Labusch parameter showed no anomaly, the interaction distance changed discontinuously near the peak field. The authors take this as evidence that the peak effect is caused by a transition of vortex lines from a three-dimensional state to a two-dimensional state. Closely related work is reported in a preprint by M. Kiuchi (SRL-ISTEC) et al.

A study by G. Ravikumar (BARC-Mumbai) et al. of history-dependent effects upon the dc and ac magnetization in single crystals of CeRu2 and 2H-NbSe2 shows that the critical current density Jc of the vortex state depends on its thermomagnetic history over a large part of (H,T) parameter space. The authors found that the path dependence of Jc is absent above the peak (i.e., H > H_p) of the peak-effect region, which the authors believe indicates a complete loss of order in the vortex structure. The highly disordered field-cooled state can be healed into a relatively ordered vortex lattice by subjecting it to a large enough change in dc field (a few tens of Oe) or by shaking it with a sufficiently high ac field (a few Oe).

As shown by W. Kim et al. (TCSUH), two g-wave components of the order parameter are induced by the internal orbital motion of d-wave pairing electrons in the presence of a magnetic field. Near a d-wave vortex center, the g-wave components with a relative phase of pi/2 have a winding number opposite that of the dominant d-wave component. The spatial dependence of the magnetically induced g-wave components is the same as that of an induced s-wave component, and each g-wave component has four-fold symmetry. The vortex thus has an eight-lobe profile.

The vortex-lattice structures of Sr2RuO4 have been examined theoretically by D. F. Agterberg (ETH-Zurich) for the odd-parity representations of the superconducting state in magnetic fields along the crystallographic directions. The author shows that when the zero- field state breaks time-reversal symmetry, there must be two superconducting transitions in finite fields along a high-symmetry direction in the basal plane. The author also predicts a square vortex lattice when the field is along the c axis.

In anisotropic or layered superconductors, both thermal fluctuations and impurities induce a van der Waals interaction between widely separated vortices. A preprint by A. Volmer (Koeln) et al. presents two derivations of the van der Waals attraction, one based on an intuitive picture and the other following a systematic expansion of the free energy of two interacting vortices. The authors use the formalism to make quantitative predictions for the low-field H-T phase diagram in Bi- 2212.

RBa2Cu3O7-d

Recent work by A. Erb et al. [Physica C 258, 9 (1996)] has shown that BaZrO3 is an excellent crucible material for crystal growth of YBa2Cu3O7-d. Since bulk BaZrO3 crucibles are both costly and fragile, J. Shi et al. (Brown) have investigated the possibility of coating BaZrO3 on the interior of less expensive, more robust crucibles. The authors have developed such a method, which employs a polymer compound containing BaZrO3 as a coating material for alumina (Al2O3) crucibles. The authors found that after a long (48 h) sintering time at high temperatures (1400-1500^oC), the coated BaZrO3 layer (optimum thickness ~0.1 mm) can be used as a diffusion barrier for crystal growth of YBa2Cu3O7-d without detectable aluminum contamination.

As reported by X. Y. Cai (Wisconsin) et al., pronounced peaks have been observed in the intergranular critical current density J_b(B) versus applied magnetic field B in YBa2Cu3O7-d bicrystals well above the lower critical field. The authors note that these peaks correspond to the fields for which the spacing between intragrain vortices is commensurate with the wavelength of the periodic grain-boundary facet structure observed in the same bicrystals. The matching effect provides direct evidence that faceting strongly modulates the coupling strength of grain boundaries and can substantially increase J_b(B) in high magnetic fields. The authors propose that the critical-current enhancement arises from periodic modulation of the intergrain coupling via strain fields at facet junctions. These strain fields have been observed by transmission electron microscopy.

A strong resonant enhancement of defect-oxygen-induced lines has been found by A. G. Panfilov (SRL-ISTEC) et al. in underdoped YBa2Cu3O7-d. Studies of the temperature dependencies of their frequencies under resonant conditions revealed softening below Tc, similar to the behavior of the in-plane-polarized B_[1g]-like mode but different from that of the zz-polarized A_[1g]-like modes. The difference in the phonon behaviors indicates an unusual interaction between the phonons and the quasi-two-dimensional electron system in the high-Tc superconductors. Above Tc, no clear phonon anomaly relevant to a pseudogap was observed.

Two preprints by A. K. Pradhan et al. (SRL-ISTEC) report on the superconducting properties of single-crystal Nd1+xBa2-xCu3O7-d (NBCO). One of the preprints reports studies of a fish-tail peak in the magnetization of a twin-free NBCO sample via minor hysteresis loops, large hysteresis loops, magneto-optical imaging, and magnetization relaxation. The results suggest that there are two pinning processes at work in this material. The other preprint reports studies of twinned NBCO single crystals via six-terminal transport measurements, resistance-versus-temperature measurements, I-V characteristics, magnetization hysteresis, magnetization relaxation, ac susceptibility, and scanning tunneling microscopy (STM). The authors conclude that Nd- Ba substitution regions act as strong pinning centers and are primarily responsible for high-field pinning. STM observations revealed that these pinning centers have dimensions of several nm to several tens of nm.

Bi Cuprates

The out-of-plane electrodynamic properties of nearly optimally doped Bi2Sr2CaCu2O8+d (Bi-2212) in the superconducting state have been studied by H. Kitano et al. (Tokyo) at 14.2 GHz using a cavity-perturbation technique with the microwave electric field parallel to the c axis. The zero crossing of the c-axis dielectric constant associated with the Josephson plasma resonance was observed just below Tc. The c-axis microwave conductivity sigma_1^c(T) was found to decrease rapidly just below Tc and to remain suppressed even in the superconducting state.

Measurements of the ac susceptibility in Bi-2212 single crystals containing columnar defects produced by heavy-ion irradiation with 250 MeV [107]^Ag^[17+] ions are reported by B. Chen et al. (SRL-ISTEC). The authors found that the superconducting transition and dissipation peak become sharper in fields B much higher than the matching field B_[phi]. The authors also conclude that line-like behavior of the vortices persists to fields well above B_[phi].

Using magneto-optical imaging, M. R. Koblischka (Trondheim) et al. have obtained the flux distributions in partial-melting-processed Bi-2212 ceramics containing embedded (Sr,Ca)2CuOy particles. The authors found that these particles, despite their relatively large size (up to 30 micrometers), are responsible for strong flux pinning, with an effect similar to that of Y2BaCuO5 (211) particles in YBa2Cu3O7-d (123).

Lattice dynamical calculations of an (001) slab of Bi-2212 bounded by BiO surfaces have been carried out by U. Paltzer (Texas-Austin) et al. The calculations, based on shell-model interactions, take proper account of the internal superstructure and surface relaxation. The authors find that the anisotropic surface structure is responsible for some unusual features of the surface phonons, including the occurrence of quasi- dispersionless surface modes and a weak direction-dependence of the surface-mode dispersion.

The reaction leading to the formation of the Pb-free Bi2Sr2Ca2Cu3O10+d (Bi-2223) phase from calcined precursor powders has been studied by J.- C. Grivel and R. Fluekiger (Geneve) using scanning electron microscopy, x-ray diffraction, and differential thermal analysis. The authors found that a complete reconstruction of the sample surface occurs during the reaction, the size of the Bi-2223 crystallites being significantly larger than that of the Bi-2212 grains present at the onset of the transformation. The authors conclude that the Pb-free Bi-2223 phase forms by nucleation and growth from a liquid phase.

The growth of the (Bi,Pb)-2223 phase has been studied by M. Yavuz (Tohoku) et al. The authors found that the 2223 phase grows from a liquid by a nucleation and growth mechanism. The major reactant 2212 remains as a solid, and its plate-like configuration determines the two- dimensional nature of the reaction. Two additional preprints by M. Yavuz (Tohoku) et al. report on the production of Bi-2223 superconductors by powder processing.

A method for joining monofilamentary Bi-2223/Ag tapes, yielding a joint with 90% of the current capacity of the tapes, is described by J. Sha et al. (Zhejiang). The silver sheath was mechanically or chemically removed from one side of each tape without disturbing the superconducting core. The exposed superconducting cores of the two tapes were brought into contact, wrapped with a thin silver foil, and pressed so as to again seal the superconductor in a silver sheath. Various reaction-anneal and mechanical treatments were performed on the joined tapes to find the optimum heat-treatment conditions.

A study of the phase equilibria in the Bi2O3-CaO system in oxygen at 1 atm pressure between 650^oC and 1050^oC is reported in a preprint by O. A. Goekcen et al. (TCSUH).

Thin Films

A process using nanolithography and a 200 keV ion implanter to fabricate planar YBa2Cu3O7-d Josephson junctions has been developed by A. S. Katz (UC-San Diego) et al. In this process, ion damage, restricted to a narrow (200-1000 Angstroms) region of the film by a polymer stencil, controllably reduces Tc and Jc to produce weak links that show classical dc and ac Josephson effects. The authors report that they can systematically tune devices to operate at temperatures between 1 K and the Tc of the undamaged superconducting material by varying the length of the weak link and changing the amount of ion damage. Measurements of R(T) and I_c(T) of the weak links revealed trends consistent with the proximity effect. The authors stress that these devices are free of interfaces, simple to fabricate, and easily scalable to large numbers of junctions.

An analysis of the microscopic properties of the Josephson barrier in electron-beam junctions scribed at low temperatures in YBa2Cu3O7-d has been carried out by B. A. Davidson (Wisconsin) et al. The junctions behave as high-quality, uniform superconducting-normal-superconducting (SNS) junctions, which allows their characteristics to be compared in detail with the results predicted by well-established SNS theory. The authors find that the barrier exhibits properties of a dirty metal near the metal-insulator transition, with a Fermi surface area reduced by an order of magnitude from that of the unirradiated film.

The effects of halogenizing HgBa2CaCu2O6+d (Hg-1212) thin films have been studied by B. W. Kang et al. (Kansas). The authors found that the addition of chlorine or fluorine significantly enhances (a) the reproducibility and stability of Hg-1212 thin films, (b) the phase purity of Hg-1212 to over 90%, and (c) the magnetic critical current density J_[c,mag] at both zero and finite field. The authors believe that the addition of Cl or F prevents Ca deficiency in the material.

Polarization-dependent x-ray-absorption spectroscopy at the Cu L_3 and Ce M_[4.5] edges has been performed by A. Yu. Ignatov (Moscow Engineering Physics Institute) et al. on epitaxial films of Nd2-xCexCuO4 versus defect concentration induced by He+ ion irradiation. The Cu L_3- edge measurements versus Ce doping indicate that about 70% of the excess electrons fill Cu 3d_[x^2-y^2] states in Nd1.85Ce0.15CuO4-d. The remaining electrons fill states that extend beyond the CuO2 planes but are localized within a few unit cells.

Laser scanning microscopy has been used by P. M. Shadrin and Y. Y. Divin (IRE-Moscow) to image electrical inhomogeneities in YBa2Cu3O7-d grain- boundary junctions with a spatial resolution of 0.1 micrometer. The authors also used this method to determine the extent of meandering of the grain boundary in the high-Tc thin film with respect to the underlying bicrystal boundary in the NdGaO3 substrate.

Applications

A preprint by B. Zeimetz et al. (Wollongong) reports the development and testing of current leads made of silver-sheathed Bi-2223 tapes. The design permits the addition or removal of individual vapor-cooled tapes to adjust the current capacity and optimize the heat leak. The minimum heat leak is obtained by tapering the leads, using more tapes at the high-temperature end. The current leads, designed for a current capacity of several kA, have been tested using applied dc currents up to 900 A.

The microwave properties of YBCO Josephson junction arrays on bicrystal MgO substrates have been investigated by I. Song (ETRE-Taejon) et al. via measurements of Josephson self-radiated power and Shapiro steps.

The design of a new type of closed-cycle cryocooler operating using the Bernoulli effect is described in a preprint by G. Kaiser et al. (Jena). The authors present the basic equations for its thermodynamic analysis, and they suggest a possible layout for the device.

Theory

An equation determining the upper critical field H_[c2||](T) parallel to the conducting planes of a quasi-two-dimensional (Q2D) superconductor has been derived by A. G. Lebed (RIAST, ETL, and Landau Institute) and K. Yamaji (ETL) from the BCS theory. The formulation extends the quasiclassical descriptions of H_[c2||](T) within the Ginzburg-Landau- Abrikosov-Gor'kov theory and the Lawrence-Doniach model to the case of arbitrarily strong magnetic fields. The authors present sketches of Tc(H) showing reentrant superconductivity for H parallel to the layers; under certain conditions, Tc(H) first decreases with H, reaches a minimum, and increases again. For p-wave superconductors, superconductivity with Tc(H) ~~ Tc(0) is restored at high fields, while for s- or d-wave superconductors under certain conditions, Tc(H) reaches a maximum and then decreases to zero at H_P, the Pauli limiting field.

The phase diagram of superconductors with mixed s- and d-wave symmetry has been studied by J.-X. Zhu, W. Kim, and C. S. Ting (TCSUH) by considering the effect of nonmagnetic impurity scattering. The authors predict that it is possible to observe the s + id state by introducing nonmagnetic impurity scattering, because it affects the d-wave superconductivity but has no influence on the s-wave superconductivity. The authors show that, surprisingly, the amplitude of the d-wave order parameter in the s + id phase decreases with decreasing temperature.

A preprint by J. A. Wilson (Bristol) addresses the one-eighth problem in high-temperature superconductors, stripe-phase formation, mixed-valent charge segregation, the Jahn-Teller effect, and 1D-to-2D crossover. The author suggests that under the action of negative-U centers of the high- valent subsystem established in the domain boundaries, the system can evolve naturally with doping and cooling from d_[x^2-y^2] towards greater s-wave-type content of the superconducting order parameter.

The perturbative-renormalization-group (PRG) method has been applied by J. Kishine and K. Yonemitsu (IMS-Okazaki) to examine dimensional crossovers in Hubbard ladders coupled via weak interladder one-particle hopping t_[perp.]. The authors set up and solved the scaling equations for the interladder one-particle and two-particle hopping amplitudes by treating the intraladder interactions and the interladder one-particle hopping as perturbations to the free-electron system on the isolated ladders. The authors found that the scaling flow toward the spin-gap- metal (SGM) phase in the isolated Hubbard ladder strongly suppresses the interladder one-particle process. Consequently, for any finite intraladder Hubbard repulsion U > 0, there exists a finite crossover value of the interladder one-particle hopping t_[perp.c].

A preprint by I. F. Herbut (UBC) argues that the system of interacting bosons at zero temperature and in a random external potential possesses a simple critical point which describes the proliferation of disorder- induced defects in the superfluid ground state, and which is located at weak disorder close to and above one dimension. This makes it possible to address the critical behavior at the superfluid-Bose glass transition in dirty boson systems by expanding around the lower critical dimension of d = 1.

Using methods of functional integration and performing simple Gaussian integrals, S. M. Chitanvis (Los Alamos) shows that an interacting system of electrons can be bosonized in arbitrary dimensions in terms of the electrostatic potential that mediates the interaction among them. Working with the bosonic field, the author shows that the system exhibits localized structures reminiscent of striping in the cuprates.

Bose-Einstein condensation temperatures T_B have been calculated by D. M. Eagles (Mexico) for noninteracting bosons in square arrays of finite- length filaments arranged on a square lattice. The author used both numerical methods and an approximate theory, which is appropriate in certain parameter ranges.

A preprint by R. De Luca (Salerno) et al. presents numerical solutions for a three-dimensional Josephson-junction array consisting of eight superconducting grains at the corners of a cube connected via Josephson junctions along the 12 cube edges. The authors studied the low-field magnetic response of the system for arbitrary directions of the applied field. The magnetic energy of the circulating currents was taken into account by introducing an effective mutual inductance matrix.

Other Activities

Methods capable of forming ordered molecular or polymeric monolayers on YBCO are described in a preprint by J. E. Ritchie (Texas-Austin) et al. Grazing reflectance infrared Fourier transform spectroscopy (GRIFTS) was employed to evaluate the degree of ordering of the monolayer structures on both c-axis-oriented YBCO thin films and polycrystalline YBCO pellets. The authors assert that these studies point the way towards the design of defect-free, corrosion-resistant surface layers that can extend the lifetimes of high-Tc structures. The authors also suggest that such surface monolayers could be used in lithographic processing of high-Tc devices and in packaging of superconductor structures.

A preprint by D. D. Lawrie (Alberta) et al. reports a search for an isotope effect in the antiferromagnetic transitions of CuO. Using isotopically pure [63]^CuO, [65]^CuO, Cu[16]^O, and Cu18]^O, the authors saw no isotope effect in either the incommensurate antiferromagnetic transition near 230 K or the commensurate antiferromagnetic transition near 210 K.

Overviews

A book chapter on thermoelectric effects in superconductors has been prepared by A. B. Kaiser (Victoria University of Wellington) and C. Uher (Michigan). The authors discuss (a) general characteristics of the thermopower (Seebeck coefficient), (b) the thermopower of superconductors in the normal phase, (c) thermomagnetic effects in the mixed state, and (d) thermoelectric applications of high-temperature superconductors. Since the thermopower of superconductors in low magnetic fields is zero, high-temperature superconductors can be used as reference materials to determine the absolute thermoelectric power of nonsuperconducting metals. High-temperature superconductors also can be used as passive elements in thermoelectric (Peltier) coolers (51 refs.).

A review of the resonant tunneling mechanism for c-axis transport in high-temperature superconducting layered cuprates has been prepared by A. A. Abrikosov (Argonne). The author describes the principles of the mechanism, calculates physical properties, and compares the calculations with data for the static c-axis conductivity in the normal state, the frequency dependence of the optical conductivity, and the stationary supercurrent along the c axis. The author also explains the decrease of Tc and the increase in 2[Delta](0)/k_BTc with underdoping in terms of the disruption of interlayer connection and the appearance of vortex fluctuations (46 refs.).

A summary of neutron and x-ray scattering studies that have provided strong evidence for coupled spatial modulations of charge and spin densities in layered nickelates and cuprates has been prepared by J. M. Tranquada (Brookhaven). The accumulated results for La2-xSrxNiO4+d are consistent with the strongly modulated topological-stripe concept, and clues from Nd-doped La2-xSrxCuO4 suggest similar behavior for the cuprates. The author also discusses features that conflict with an interpretation based on a Fermi-surface instability (45 refs.).

A preprint by B. Brandow (Los Alamos) summarizes the results of a comprehensive examination of the characteristic features of the exotic superconductors, as defined by Y. J. Uemura et al. [Phys. Rev. Lett. 66, 2665 (1991) and Physica B 186-188, 223 (1993)]. In both electronic and crystal-chemistry properties, the author finds anomalous features that appear to be universal for these materials, as well as other features that are clearly not universal but common enough to be considered typical for these materials. (13 refs.).

Contributed by John R. Clem

Contents: Technology News is on page 6; Preprints begin on page 6; Coming Events begin on page 11; Resources begin on page 12; and FYI is on page 13.

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.

Scientists at the Institute for Biochemical Physics, Russian Academy of Sciences, and Queen's University, Canada, report results on the design and testing of a cryostat that demonstrates superconducting levitation in a room-temperature environment. The superconducting stator, consisting of melt-textured HTS material, is within a cryostat maintained at 77 K. The rotor levitates above the cryostat wall that is at room temperature. Application of this technology can be in systems where the levitated object must operate at temperatures substantially above 77 K, such as flywheels, bearings, pumps, non-contact transportation sensors, centrifuge systems, clean-room transportation, and non-contact vibration isolation systems. The cryostat is portable and weighs 5 kg, and levitation of the permanent magnet above the warm wall of the cryostat has been tested and demonstrated for three hours. For information, contact Alexandre Terentiev, Department of Physics and Astronomy, University of Kentucky, Lexington, KY 40506-0055; telephone (606) 257-2300, ext. 282; telefax (606) 323-2846; e-mail atere0@pop.uky.edu.

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.

A. A. Abrikosov, "Resonant Tunneling in High-Tc Superconductors." Submitted to Soviet Phys. Contact Janice Coble, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439; telefax (708) 252-9595; e-mail janice_coble@qmgate.anl.gov.

D. F. Agterberg, "Vortex Lattice Structures of Sr2RuO4." Institut fuer Theoretische Physik, ETH-Hoenggerberg, CH-8093 Zurich, SWITZERLAND; telephone +41 1 633-2575 or -2570; telefax +41 1 633-1115; e-mail daniel@itp.phys.ethz.ch; preprint also available at cond- mat@xxx.lanl.gov (#9802151). 74.20.Mn; 74.25.Bt.

Baird Brandow, "Characteristic Features of the Exotic Superconductors: A Summary." Preprint #LA-UR-97-3703; presented at the 1997 Conf. on Spectroscopies in Novel Supercond. (SNS'97), Falmouth, Mass., Sept. 14- 18, 1997; submitted to J. Phys. Chem. Solids. Center for Nonlinear Studies, Los Alamos National Laboratory, Los Alamos, NM 87545.

X. Y. Cai, A. Gurevich, I.-Fei Tsu, D. L. Kaiser, S. E. Babcock, and D. C. Larbalestier, "Large Enhancement of the Critical Current Density Due to Vortex Matching at Periodic Facet Structure in YBa2Cu3O7-d Bicrystals." To be published in Phys. Rev. B. Applied Superconductivity Center, University of Wisconsin-Madison, Madison, WI 53706. 74.60.Ge; 74.60.-w.

B. Chen, A. K. Pradhan, N. Koshizuka, D. Kanjilal, A.J.S. Chowdhury, and B. M. Wanklyn, "Effects of Columnar Defects on ac Susceptibility of Bi2Sr2Ca1Cu2Ox Single Crystals." To be published in Solid State Commun. Superconductivity Research Laboratory, International Superconductivity Technology Center (ISTEC), 10-13 Shinonome 1-chome, Koto-ku, Tokyo 135, JAPAN; telephone +81 3 3536-5703 or -5704; telefax +81 3 3536-5714 or -5717; e-mail bc@istec.or.jp. Key words: superconductors, flux pinning.

Shirish M. Chitanvis, "Bosonization in Arbitrary Dimensions." Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM 87545; e-mail shirish@boron.lanl.gov; preprint also available at cond- mat@xxx.lanl.gov (#9802077). 71.10.Pm.

D. B. Currie and M. T. Weller, "Nickel Substitution in Ln2Ba4Cu7- xNixO14+d: Ln = Lanthanide, Yttrium." To be published in Physica C (in press). Contact M. T. Weller, Department of Chemistry, University of Southampton, Southampton SO17 1BJ, UNITED KINGDOM; telephone +44 170 359 5000; telefax +44 170 359 3781.

B. A. Davidson, J. E. Nordman, B. Hinaus, M. Rzchowski, K. Siangchaew, and M. Libera, "Microscopic Barrier Properties in Electron-Beam Scribed YBCO Josephson Junctions." To be published in Appl. Supercond. Istituto di Cibernetica-CNR, via Toiano 6, I-80072 Arco Felice, ITALY.

R. De Luca, T. Di Matteo, A. Tuohimaa, and J. Paasi, "Three-Dimensional Josephson Junction Arrays: Static Magnetic Response." To be published in Phys. Rev. B. INFM Dipartimento di Fisica, Universita degli Studi di Salerno, I-84081 Baronissi (Salerno), ITALY. 74.50.+r; 74.60.Ge.

D. M. Eagles, "Bose-Einstein Condensation in Finite-Length Channels Composed of Weakly Interacting Filaments." To be published in Physica C. Instituto de Investigaciones en Materiales, Universidad Nacional Autonoma de Mexico, Apartado Postal 70-360, 04510 Mexico D.F., MEXICO; telefax +52 5 616 1251; e-mail eagles@servidor.unam.mx (after April 1, 1998: 56 Portland Road, Tottenham, London N15 4SX, UNITED KINGDOM). Key words: Bose-Einstein condensation, filament arrays, superconductivity.

Yong Feng, J. G. Wen, N. Koshizuka, Lian Zhou, A. Sulpice, J. L. Tholence, J. C. Vallier, and P. Monceau, "Fishtail Effect, Magnetic Properties and Critical Current Density of Gd-Added PMP YBCO." To be published in Physica C (in press). Northwest Institute for Nonferrous Metal Research, P.O. Box 51, Xi'an, Shaanxi 710016, PEOPLE'S REPUBLIC OF CHINA; telephone +86 29 622 4487; telefax +86 29 623 1103; e-mail smrc@pub.online.xa.sn.cn. Key words: YBCO, fishtail effect, flux pinning, Gd addition. 74.72.Bk; 74.60.Ge; 74.60.Jg.

O. A. Goekcen, J. V. Styve, J. K. Meen, and D. Elthon, "Phase Equilibria of the 1/2(Bi2O3)-CaO System in Oxygen at 1 atm Pressure." Preprint #98:020; submitted to J. Amer. Ceram. Soc. Texas Center for Superconductivity, University of Houston, Houston, TX 77204-5932; telephone (713) 743-8200; telefax (713) 743-8201; e-mail preprints@www.tcs.uh.edu.

J.-C. Grivel and R. Fluekiger, "Formation Mechanism of the Pb Free Bi2Sr2Ca2Cu3O10 Phase." To be published in Supercond. Sci. Technol. (in press). Department of Solid State Physics, Royal Institute of Technology, Teknikringen 14, S-100 44 Stockholm, SWEDEN; e-mail jcg@ftf.kth.se.

Igor F. Herbut, "Critical Behavior at Superconductor-Insulator Phase Transitions Near One Dimension." Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, BC, CANADA V6T 1Z1; e-mail herbut@black-hole.physics.ubc.ca; preprint also available at cond-mat@xxx.lanl.gov (#9802141). 74.40.+k; 05.30.Jp; 05.70.Jk.

F. G. Hill, M. Getta, M. A. Hein, G. Mueller, H. Piel, B. Dam, S. Beuven, J. Schubert, and W. Zander, "Influence of Film Growth Conditions on the Transport Properties of YBa2Cu3O7-d Step-Edge Junctions." To be published in Appl. Supercond. Fachbereich Physik, Universitaet Wuppertal, Gausstr. 20, D-42097 Wuppertal, GERMANY.

J. Horvat, Y. C. Guo, and S. X. Dou, "Difference in Mechanical Properties of Weak and Strong Links in Bi-2223/Ag Superconducting Tapes." To be published in Physica C (in press). Centre for Superconducting and Electronic Materials, University of Wollongong, Wollongong NSW 2522, AUSTRALIA; telephone +61 42 214731; telefax +61 42 215731; e-mail jhorvat@uow.edu.au. Key words: weak links, strong links, critical current density, grain boundaries, flux pinning.

A. Yu. Ignatov, A. A. Ivanov, A. P. Menushenkov, S. Iacobucci, and P. Lagarde, "Symmetry of the Free States of an Electron-Doped Nd2-xCexCuO4- d Superconductor Determined by X-ray-Absorption Spectroscopy." To be published in Phys. Rev. B. Department of Quantum Electronics, Moscow Engineering Physics Institute, Kashirskoe shosse 31, 115409 Moscow, RUSSIA; e-mail ignatov@htsc.mephi.ru. 74.25.Jb; 74.62.Dh; 78.70.Dm; 61.80.-x.

S. Jandl, P. Richard, J. Trottier, K. Frikach, M. Poirier, D. I. Zhigunov, S. N. Barilo, and S. V. Shiryaev, "Infrared and Microwave Studies of Defects in Nd2CuO4." To be published in Physica C (in press). Centre de Recherche en Physique du Solide, Departement de Physique, Universite de Sherbrooke, Sherbrooke, Quebec, CANADA J1K 2R1; telephone (819) 821-8000; telefax (819) 821-8046.

A. B. Kaiser and C. Uher, "Thermoelectric Effects of Superconductors." To be published in Handbook of Appl. Supercond., edited by B. Seeber (Inst. of Physics Publishing, Bristol, 1998). Department of Physics, Victoria University of Wellington, P.O. Box 600, Wellington, NEW ZEALAND.

G. Kaiser, L. Reissig, M. Thuerk, and P. Seidel, "About a New Type of Closed-Cycle Cryocooler Operating Using the Bernoulli Effect." Submitted to Cryogenics. Institut fuer Festkoerperphysik, Friedrich- Schiller-Universitaet Jena, Max-Wien-Platz 1, D-07743 Jena, GERMANY. Key words: cryocooler, Bernoulli effect, microstructure, low power, low noise, neon.

B. W. Kang, A. A. Gapud, X. Fei, T. Aytug, and J. Z. Wu, "Minimization of Detrimental Effect of Air in HgBa2CaCu2O6+d Thin Film Processing." To be published in Appl. Phys. Lett. Department of Physics and Astronomy, University of Kansas, Lawrence, KS 66045-2151; e-mail kang@kubeam.phsx.ukans.edu. Key words: high-temperature superconductivity, thin films, chlorine, fluorine, Hg-1212. 74.72.-h; 74.62.Bf.

A. S. Katz, A. G. Sun, S. I. Woods, and R. C. Dynes, "Planar Thin Film YBa2Cu3O7-d Josephson Junctions Via Nanolithography and Ion Damage." To be published in Appl. Phys. Lett. Contact R. C. Dynes, University of California at San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0319; A. S. Katz's telephone (619) 534-2919; telefax (619) 534-2232. 74.50.+r; 85.40.Hp; 74.62.Dh; 74.76.Bz.

W. K. Kim, J. X. Zhu, and C. S. Ting, "Magnetic Induction of High Angular Momentum Pairing Symmetry." Preprint #98:023; to be published in 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. 74.20.De; 74.20.Mn.

Jun-ichiro Kishine and Kenji Yonemitsu, "Dimensional Crossovers in the Doped Ladder System: Spin Gap, Superconductivity and Interladder Coherent Band Motion." To be published in J. Phys. Soc. Jpn. Department of Theoretical Studies, Institute for Molecular Science, Okazaki 444-8585, JAPAN; telefax +81 564 54 2254; e-mail kishine@ims.ac.jp; preprint also available at cond-mat@xxx.lanl.gov (#9802185). Key words: doped ladder, dimensional crossover, perturbative renormalization group, spin gap metal, bipolaron condensation, d-wave superconductivity.

H. Kitano, T. Hanaguri, and A. Maeda, "c-Axis Microwave Conductivity of Bi2Sr2CaCu2Oy in the Superconducting State." To be published in Phys. Rev. B. Department of Basic Science, University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153, JAPAN; telephone +81 3 5454 6763; telefax +81 3 5454 6763; e-mail cc67904@komaba.ecc.u-tokyo.ac.jp. 74.25.Nf; 74.72.Hs; 74.25.-q.

M. Kiuchi, H. Yamato, T. Hirano, T. Matsushita, and N. Koshizuka, "Force-Displacement Characteristics of Fluxoids Along the c-Axis in Superconducting Bi-2212 Single Crystal Near the Peak Field." To be published in Physica C (in press). Contact T. Matsushita, Department of Computer Science and Electronics, Kyushu Institute of Technology, 680-4 Kawazu, Iizuka 820, JAPAN; telephone +81 948 29 7663; telefax +81 948 29 7683; e-mail matusita@cse.kyutech.ac.jp.

M. R. Koblischka, S. L. Huang, K. Fossheim, T. H. Johansen, and H. Bratsberg, "Evidence for Pinning by (Sr,Ca)2CuOy Particles in Partial- Melting Processed Bulk Bi2Sr2CaCu2O8+d Ceramics." Contact T. H. Johansen, Department of Physics, University of Oslo, N-0316 Oslo, NORWAY; e-mail t.h.johansen@fys.uio.no. 74.60.Ec; 74.60.Ge; 74.60.Jg.

Suman Kumari and O. N. Srivastava, "On the Special Synthesis of YBa2Cu4Od Thin Films by Spray Pyrolysis Through Ca Substitution and AgNO3 Admixture." To be published in Physica C (in press). Contact O. N. Srivastava, Department of Physics, Banaras Hindu University, Varanasi 221005, INDIA; telephone +91 542 36 1937; telefax +91 542 31 7478. Key words: superconductors, transition temperature, critical current.

D. D. Lawrie, J. P. Franck, and Cheng-Tian Lin, "Search for an Isotope Effect in the Antiferromagnetic Transitions of Cupric Oxide CuO." To be published in Physica C (in press). Contact J. P. Franck, Department of Physics, University of Alberta, Edmonton, Alberta, CANADA T6G 2J1; telephone (403) 492-7835; telefax (403) 492-4256. Key words: isotope effect, antiferromagnetic order. 75.50.Ee.

A. G. Lebed and K. Yamaji, "Restoration of Superconductivity in High Parallel Magnetic Fields in Layered Superconductors." To be published in Phys. Rev. Lett. RIAST, Osaka Prefecture University, Gakuen-cho 1-2, Sakai 599, JAPAN. 74.60.Ec; 74.70.Kn.

Hee-Gyoun Lee, Woen-Ju Kim, Gye-Won Hong, Min-Hyung Lee, and Hyun-Soon Park, "Effects of Pressing on the Current Flow in a Ag/Bi-2223 Tape." To be published in Physica C (in press). Superconductivity Research Department, Korea Atomic Energy Institute, P.O. Box 105, Yousung 305- 600, SOUTH KOREA; telephone +82 42 868 8026; telefax +82 42 862 5496; e- mail hglee@nanum.kaeri.re.kr. Key words: critical current, Ag/Bi-2223 tape, pressing, strain.

H.C.F. Martens, W. T. Fu, J. A. Reedijk, J. Adriaanse, and H. B. Brom, "The Superconductor Insulator Transition in Ce Substituted BaPb1- xBixO3." To be published in Physica C (in press). Kamerlingh Onnes Laboratory, Leiden University, P.O. Box 9506, 2300 RA Leiden, THE NETHERLANDS; telephone +31 71 527 5427; telefax +31 71 527 5404; e-mail martens@rulkol.leidenuniv.nl. 74.25.-q; 74.25.Fy; 74.62.Dh.

M. S. Martin-Gonzalez, J. Garcia-Jaca, E. Moran, and M. A. Alario- Franco, "Synthesis of BaBiO3 and Ba1-xKxBiO3 Films via an Electrodeposition Process." To be published in Physica C (in press). Contact M. A. Alario-Franco, Departamento de Quimica Inorganica, Facultad de Ciencias Quimicas, Universidad Complutense de Madrid, Ciudad Universitaria, E-28040 Madrid, SPAIN; telephone +34 1 394 4338; telefax +34 1 394 4352; e-mail maaf@eucmax.sim.ucm.es. Key words: superconductors, electrodeposition, films, BaBiO3, Ba1-xKxBiO3.

T. Matsushita, T. Hirano, H. Yamato, M. Kiuchi, Y. Nakayama, J. Shimoyama, and K. Kishio, "Peak Effect of Critical Current in Bi-2212 Superconducting Single Crystal." Kyushu Institute of Technology, 680-4 Kawazu, Iizuka 820, JAPAN; e-mail matusita@cse.kyutech.ac.jp.

V. V. Moshchalkov, "Crossover from the 2D Heisenberg to the 1D Quantum Spin Ladder Regime in Underdoped High-Tc Cuprates." To be presented at the 1998 March Meeting of the Amer. Phys. Soc., Los Angeles, Calif., Mar. 16-20, 1998; submitted to Phys. Rev. Lett. Laboratorium voor Vaste-Stoffysica en Magnetisme, Katholieke Universiteit Leuven, Celestijnenlaan 200 D, B-3001 Leuven, BELGIUM; preprint also available at cond-mat@xxx.lanl.gov (#9802281). 75.10.Jm; 74.25.Fy; 74.20.Mn.

V. V. Moshchalkov, L. Trappeniers, and J. Vanacken, "1D Quantum Transport in the Even-Chain Spin-Ladder Compound Sr2.5Ca11.5Cu24O41 and YBa2Cu4O8." Submitted to Europhys. Lett. Laboratorium voor Vaste- Stoffysica en Magnetisme, Katholieke Universiteit Leuven, Celestijnenlaan 200 D, B-3001 Leuven, BELGIUM. 75.10.Jm; 74.25.Fy; 74.20.Mn.

A. Oral, J. C. Barnard, S. J. Bending, I. I. Kaya, S. Ooi, T. Tamegai, and M. Henini, "Direct Observation of Melting of the Vortex Solid in Bi2Sr2CaCu2O8+d Single Crystals." To be published in Phys. Rev. Lett. Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, UNITED KINGDOM; telephone +44 1865 273700; telefax +44 1865 273789; e-mail ahmet.oral@materials.oxford.ac.uk or enquiries@materials.oxford.ac.uk. 74.60.Ge; 74.25.Dw; 74.72.Hs.

U. Paltzer, F. W. de Wette, U. Schroeder, and E. Rampf, "Surface Dynamics of Bi2CaSr2Cu2O8." Department of Physics, University of Texas, Austin, TX 78712-1081.

A. G. Panfilov, M. F. Limonov, A. I. Rykov, S. Tajima, and A. Yamanaka, "Superconductivity-Induced Effect on 'Raman-Forbidden' Modes in Underdoped YBa2Cu3O7-x Single Crystals." Submitted to Phys. Rev. B. 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. 63.20.Kr; 74.25.Kc; 74.72.Bk.

A. K. Pradhan, B. Chen, Wu Ting, K. Kuroda, K. Nakao, and N. Koshizuka, "Flux Dynamics of Nd1+xBa2-xCu3O7-d Single Crystals in the Presence of Disorders by Substitution." To be published in Supercond. Sci. & Technol. 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; e-mail pradhan@istec.or.jp.

A. K. Pradhan, K. Kuroda, T Takagi, and N. Koshizuka, "Magnetization Hysteresis Loops and Relaxation in a Twin-Free Nd1+xBa2-xCu3O7-y Single Crystal." To be published in Physica C. 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; e-mail pradhan@istec.or.jp. Key words: minor and large hysteresis loops, critical current density, flux pinning, relaxation.

G. Ravikumar, V. C. Sahni, P. K. Mishra, T. V. Chandrasekhar Rao, S. S. Banerjee, A. K. Grover, S. Ramakrishnan, S. Bhattacharya, M. J. Higgins, E. Yamamoto, Y. Haga, M. Hedo, Y. Inada, and Y. Onuki, "Manifestation of History Dependent Critical Currents Via dc and ac Magnetization Measurements in Single Crystals of CeRu2 and 2H - NbSe2." To be published in Phys. Rev. B. Technical Physics and Prototype Engineering Division, Bhabha Atomic Research Centre, Mumbai 400 085, INDIA; S. S. Banerjee's e-mail satya@tifrc2.tifr.res.in; preprint also available at cond-mat@xxx.lanl.gov (#9801247). Key words: multivalued critical currents, path dependence, weakly pinned superconductors, peak effect, CeRu2, NbSe2. 64.70.Pf; 74.60.Ge; 74.25.Ha; 74.70.Ad; 74.60.Jg.

Jason E. Ritchie, Cyndi A. Wells, Ji-Ping Zhou, Jianai Zhao, John T. McDevitt, Carl R. Ankrum, Luckner Jean, and David R. Kanis, "Infrared and Computational Studies of Spontaneously Adsorbed Amine Reagents on YBa2Cu3O7: Structural Characterization of Monolayers Atop Anisotropic Superconductor Surfaces." To be published in J. Am. Chem. Soc. Contact John T. McDevitt, Department of Chemistry, University of Texas at Austin, Austin, TX 78712-1167; telephone (512) 471-0046; telefax (512) 471-8696; e-mail mcdevitt@huckel.cm.utexas.edu.

S. B. Roy and P. Chaddah, "Comment on 'A Novel Technique to Measure Magnetization Hysteresis Curves in the Peak Effect Regime of Superconductors.'" Low Temperature Physics Group, Centre for Advanced Technology, Indore 452013, INDIA.

J. Sha, X. J. Chen, Z. B. Wang, X. S. Ye, and Z. K. Jiao, "A New Method for Joining of Bi(2223)/Ag Tapes." To be published in Physica C (in press). Department of Physics, Zhejiang University, Zhejiang Hangzhou 310027, PEOPLE'S REPUBLIC OF CHINA. Key words: superconducting joint, Bi(2223)/Ag tape, critical current. 74.60.Jg; 81.20.Ev; 81.40.Ef.

P. M. Shadrin and Y. Y. Divin, "Submicrometer Electrical Imaging of Grain Boundaries in High-Tc Thin-Film Junctions by Laser Scanning Microscopy." To be published in Physica C (in press). Institute of Radioengineering and Electronics of Russian Academy of Sciences, Moscow 103907, RUSSIA; telephone +7 95 203 4987; telefax +7 95 203 8414; e-mail psh@web.cplire.ru. Key words: thin films, Josephson junctions, grain boundaries, electrical imaging.

Jing Shi, J. E. Berger, and X. S. Ling, "Growth of YBa2Cu3O7-d Crystals with BaZrO3-Coated Alumina Crucibles." Submitted to Physica C. Contact X. S. Ling, Department of Physics, Brown University, Providence, RI 02912; e-mail xsling@brown.edu.

Insang Song, Ilho Lee, Kwang-Yong Kang, Ihun Song, Sangmin Lee, Yunsung Huh, and Gwangseo Park, "Self-Radiation Power and Microwave Coupling of YBCO Josephson Junction Arrays on Bicrystal MgO Substrates." To be published in Physica C (in press). Research Department, Electronics and Telecommunications Research Institute, Yusong, P.O. Box 106, Taejon 305- 600, SOUTH KOREA. Key words: Josephson junction, self-radiation power, Shapiro steps, received power. 85.25.Am; 85.25.Cp; 85.25.Na; 85.25.Pb.

U. Syamaprasad, M. S. Sarma, P. Guruswamy, V. Prakash Kumar, R. Ragini, K.G.K. Warrier, and A. D. Damodaran, "Effect of Precursor Phase Assemblage on 2223 Phase Formation and Jc in Ag/(Bi,Pb)-2223 Tapes." To be published in Physica C (in press). Regional Research Laboratory (CSIR), Trivandrum 695 019, INDIA; telefax +91 471 490 186; e-mail smail@csrrltrd.ren.nic.in. Key words: Ag/(Bi,Pb)-2223 tapes, precursor phase assemblage, phase evolution, in-situ phase formation, Jc enhancement.

J. M. Tranquada, "Charge Stripes and Antiferromagnetism in Insulating Nickelates and Superconducting Cuprates." To be published in J. Phys. Chem. Solids: Proc. of the Conf. on Spectroscopies in Novel Supercond. (SNS'97), Cape Cod, Mass., Sept. 14-18, 1997. Department of Physics, Brookhaven National Laboratory, Upton, NY 11973; e-mail jtran@bnlarm.bnl.gov; preprint also available at cond-mat@xxx.lanl.gov (#9802043).

Andreas Volmer, Sutapa Mukherji, and Thomas Nattermann, "Van der Waals Interaction Between Flux Lines in High-Tc Superconductors." Submitted to Eur. Phys. J. Institut fuer Theoretische Physik, Universitaet zu Koeln, Zuelpicher Str. 77, D-50937 Koeln, GERMANY; telephone +49 221 470 4202; telefax +49 221 470 5159; e-mail av@thp.uni-koeln.de; preprint also available at cond-mat@xxx.lanl.gov (#9802090). 74.60.Ec; 74.60.Ge.

John A. Wilson, "The Position of the 'One-Eighth' Anomaly Within the HTSC Problem: Matters Concerning Stripes and Domains, Jahn-Teller and Negative-U Behavior." To be published in J. Phys. Condens. Matter. H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL, UNITED KINGDOM; telephone +44 117 928 8710. Key words: HTSC mechanism, stripes, "1/8 anomaly", mixed-valent systems.

S. Y. Xu, C. K. Ong, Y. L. Zhou, B. L. Low, L. F. Chen, and X. Zhang, "The Effects of Heating and Annealing Processes on the Surface Morphology and Quality of Double-Sided YBa2Cu3O7-d Thin Films." To be published in Physica C (in press). Department of Physics, National University of Singapore, Kent Ridge Road, Singapore 119260, SINGAPORE; telephone +65 772 6678; telefax +65 777 6126. Key words: double-sided YBCO thin films, pulsed-laser deposition, surface morphology, annealing.

Mustafa Yavuz, Hiroshi Maeda, Lou Vance, Huan Kuan Liu, and Shi Xue Dou, "Effect of Ball Milling Materials and Methods on Powder Processing of Bi-2223 Superconductors." To be published in the Proc. of the Int. Symp. on Processing and Critical Currents of HTS, Wagga Wagga, Australia, Feb. 2-4, 1998. Institute for Materials Research, Tohoku University, Katahira 2-1-1, Sendai 980-77, JAPAN; telefax +81 22 215 2705; e-mail myavuz@imr.tohoku.ac.jp.

Mustafa Yavuz, Hiroshi Maeda, Lou Vance, Huan Kuan Liu, and Shi Xue Dou, "Phase Development and Kinetics of High Temperature Bi-2223 Phase." Submitted to J. Alloys and Compounds. Institute for Materials Research, Tohoku University, Katahira 2-1-1, Sendai 980-77, JAPAN; telefax +81 22 215 2705; e-mail myavuz@imr.tohoku.ac.jp. Key words: high-Tc superconductivity, phase formation and kinetics.

Mustafa Yavuz, Hiroshi Maeda, Lou Vance, Huan Kuan Liu, and Shi Xue Dou, "Powder Production Methods of Bi-Pb-Sr-Ca-Cu-O Superconductors." To be published in the Proc. of the Int. Symp. on Processing and Critical Currents of HTS, Wagga Wagga, Australia, Feb. 2-4, 1998. Institute for Materials Research, Tohoku University, Katahira 2-1-1, Sendai 980-77, JAPAN; telefax +81 22 215 2705; e-mail myavuz@imr.tohoku.ac.jp.

Bernhard Zeimetz, Shi Xue Dou, and Hua Kun Liu, "Recrystallization Effects and Grain Size in Bi(2223) Tapes." To be published in Supercond. Sci. & Technol.: Proc. of the Int. Symp. on Processing and Critical Currents of HTS, Wagga Wagga, Australia, Feb. 2-4, 1998. Institute for Superconducting and Electronic Materials, University of Wollongong, Wollongong NSW 2522, AUSTRALIA; telephone +61 2 4221 5766; telefax +61 2 4221 5731; e-mail bpz01.uow.edu.au.

Bernhard Zeimetz, Shi Xue Dou, and Hua Kun Liu, "Vapor Cooled High Tc Current Leads Utilizing Bi2223/Ag Tapes." To be published in Supercond. Sci. & Technol.: Proc. of the Int. Symp. on Processing and Critical Currents of HTS, Wagga Wagga, Australia, Feb. 2-4, 1998. Institute for Superconducting and Electronic Materials, University of Wollongong, Wollongong NSW 2522, AUSTRALIA; telephone +61 2 4221 5766; telefax +61 2 4221 5731; e-mail bpz01.uow.edu.au.

Guo-Meng Zhao, A.P.B. Sinha, and Donald E. Morris, "Cause of Tc Depression in Sr Substituted YBaSrCu3O7-y Examined by Isotope Studies." To be published in Physica C (in press). Contact A.P.B. Sinha, Morris Research, Inc., 44 Marguerita Road, Kensington, CA 94707; telephone (510) 525-3070; telefax (510) 548-5485. 74.62.Dh; 74.72.Dn.

J. X. Zhu, W. K. Kim, and C. S. Ting, "Enhancement of Broken-Time- Reversal-Symmetry Pairing State in d-Wave Superconductors with Nonmagnetic Impurities." Preprint #98:022; to be published in 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. 74.25.Dw; 74.20.Fg.

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

*July 18 - 26, 1998: 4th International Summer School on High Temperature Superconductivity, Eger, Hungary. Organized by Hungarian Chapter of Superconductivity Society. The main frame of the Summer School is a series of tutorial lectures by well-known scientists. Round-table sessions to be organized to provide time for free discussions. Topics are: the second ten years of high-temperature superconductivity, survey of theories on high-Tc superconductivity, physical properties of high-Tc materials, characterization and measurements of the physical properties, new trends in preparation techniques, crystal structure of high-Tc materials, manufacturing of high-Tc conductors, and small- and large-scale applications. Last two days will be devoted to a scientific conference where participants can present results of their own work. Oral and poster presentations will be selected by the Local Organizing Committee. Papers to be published in the Proceedings of the Summer School. Abstract deadline, April 1, 1998. Scientific correspondence is to be addressed to Istvan Vajda, Department of Electrical Machines and Drives, Technical University of Budapest, H-1111 Budapest, Egry Jozsef u. 18., Hungary; telephone +36 1 463 2961; telefax +36 1 463 3600; e-mail vajda@ntb.bme.hu; Web site http://docs4.mht.bme.hu/~farkas/. For other matters, contact Attila Varga or Klara Langthe, Conference Secretariat, Diamond Congress Ltd., H-1255 Budapest, P.O. Box 48, Hungary; telephone +36 1 214 7701; telefax +36 1 201 6383; e-mail diamond.eft@mtesz.hu. (Note new abstract deadline.)

July 19 - 24, 1998: Gordon Research Conference on Correlated Electron Systems, Plymouth State College, Plymouth, New Hampshire. Conference will survey significant experimental and theoretical developments in the study of electronic correlations in the cuprates and related materials, heavy-fermion systems, and two-dimensional electron gases. Co-Chairs: Laura H. Greene and Subir Sachdev. The conference will begin with a formal session of invited talks; additional formal sessions will be held on the mornings and evenings of the following Monday through Thursday. A substantial block of time will be set aside for discussions to be coordinated by the session chair. Contributed poster sessions will be held in the afternoons and discussion on the posters will also be integrated into the formal sessions. Topics are: spin chains and ladders, mesoscopic superconductivity, broken time-reversal symmetry, correlated fermions in adsorbed layers, one-dimensional conductors, heavy fermions, and two-dimensional electron gas. All prospective attendees (including invited speakers) must submit an application. Application deadline, June 5, 1998. For information, contact Gordon Research Conferences, University of Rhode Island, P.O. Box 984, West Kingston, RI 02892-0984; telephone (401) 783-4011; telefax (401) 783- 7644; e-mail app@grcmail.grc.uri.edu (for application form requests) or grc@grcmail.grc.uri.edu (for general information). Information also available at Web site http://sachdev.physics.yale.edu/grc/index.html.

Aug. 9 - 14, 1998: Nordic Researcher Course on Power Applications for Superconductivity, Hotel Frederiksdal, Copenhagen, Denmark. The aim of this course is to impart knowledge to the participating candidates about power applications for superconductivity -- an emerging new technology which is expected to have a major impact on the future electric power generation, transmission and distribution systems. Candidates will learn about basic properties of superconductors, high-temperature superconductors, and manufacturing aspects as conductors for power applications. Power applications in cables, transformers, fault current limiters, energy storage, and motors will be discussed by specialists within these areas. Travel and lodging costs for the Nordic Ph.D. students will be paid for by NorFA. For more information, contact B. Hald, Department of Electric Power Engineering, Bldg. 325, Technical University of Denmark, DK-2800 Lyngby, Denmark; telephone +45 4525 3510; telefax +45 4588 6111; e-mail B.Hald@eltek.dtu.dk or ot@eltek.dtu.dk; Web site http://www.eltek.dtu.dk.

Sept. 6 - 11, 1998: Gordon Research Conference on Superconductivity: Cuprate Superconductors and Related Materials, Queen's College, Oxford, United Kingdom. Colin Gough, Chair; M. Brian Maple, Vice Chair. Sessions are: recent theoretical developments, influence of pairing symmetry on properties, normal-state pseudogap, vortex matter, new materials, proximity coupling with CMR and other materials. For information, contact Gordon Research Conferences, University of Rhode Island, P.O. Box 984, West Kingston, RI 02892-0984; telephone (401) 783-4011; telefax (401) 783-7644; e-mail app@grcmail.grc.uri.edu (for application form requests) or grc@grcmail.grc.uri.edu (for general information).

Sept. 10 - 15, 1998: XXII International School of Theoretical Physics -- Quantum Coherence in Superconductors and Nanostructures, Ustron, Poland. Topics include quantum coherence in nanostructures, Coulomb blockade in quantum dots, strongly correlated electrons in high- temperature superconductivity, and coherent phenomena in superconductors. Abstract deadline, May 30, 1998; registration deadline, June 30, 1998. For information, contact Elzbieta Zipper, Institute of Physics, University of Silesia, ul. Uniwersytecka 4, 40-007 Katowice, Poland; telephone +48 32 583653; telefax +48 32 588431; e- mail: thschool@us.edu.pl; Web site http://server.phys.us.edu.pl/thschool/.

*Sept. 13 - 18, 1998: The 1998 Applied Superconductivity Conference (ASC), Marriott's Desert Springs Resort, Palm Desert, Calif. Conference encourages contributed papers in three major areas of applied superconductivity: electronics, materials, and large-scale applications. For 1998, the theme Superconductivity -- Coming to Market, will be developed through a series of plenary and invited talks. Abstracts are solicited for papers that show a clear connection to applied superconductivity. Abstract deadline for submission via the ASC Web site, March 16, 1998. Selected papers will be published in IEEE Transactions on Appl. Supercond. For information about the conference and programs for companions, contact Centennial Conferences, 4800 Baseline Rd., A-112, Boulder, CO 80303; telephone (303) 499-2299; telefax (303) 499-2599; e-mail centennial@orci.com; Web site http://www.ascinc.org. For submission of abstracts or technical information, contact Ron Scanlan, Applied Superconductivity Conference, Lawrence Berkeley National Laboratory, 1 Cyclotron Rd., MS 46-161, Berkeley, CA 94720; telephone (510) 486-7241; telefax (510) 486-5310; e- mail rmscanlan@lbl.gov; Web site http://www.ascinc.org.

Oct. 19 - Nov. 6, 1998: Experimental Workshop on High Temperature Superconductors and Related Materials, San Carlos de Bariloche, Argentina. Organized by International Centre for Theoretical Physics (ICTP) and Centro Atomico Bariloche (CAB). This is the second workshop and intends to provide a general view of the state-of-the-art in the different areas of research. Its main purpose is to present to the participants the personal view of the invited speakers on new research areas to be developed in the near future. Topics to be covered are: nature of the normal and superconducting state of copper oxides; thermodynamics and transport properties of the vortex structure in the liquid and solid state; normal and superconducting properties of artificial low-dimensional systems; new superconducting and related materials; material properties and characterization; optical properties of high temperature superconductors; non-conventional superconductors; and trends in applications of HTSC materials. Workshop is open to research workers from all countries that are members of the United Nations, UNESCO, or IAEA. No registration fee. Deadline for request for participation April 30, 1998. For information, contact the Abdus Salam International Centre for Theoretical Physics, P.O. Box 586, I- 34100 Trieste, Italy; telephone +39 40 2240111; telefax +39 40 224163.

Oct. 17 - 22, 1999: Fifth Symposium on Low Temperature Electronics -- 196th Electrochemical Society Meeting, Honolulu, Hawaii. Symposium is intended to provide a forum for discussion of the latest developments and evolutions in the field of low-temperature electronics. Besides providing an opportunity to review developments since the last symposium, it will focus on new aspects of electronic materials, devices, and systems operating at cryogenic temperatures. Will consist of both invited and contributed papers. Contributed papers are solicited in the following areas: 1) Fundamentals: theoretical limitations and restrictions, physical phenomena, new low temperature effects; 2) Devices: semiconductor components, infrared components, optoelectronic devices, hybrid and monolithic integration, nanostructures and novel devices, processing, modeling, etc.; 3) Circuits: integrated circuits; digital and analog, charge-coupled devices and read out circuits, low temperature systems, design considerations; 4) Systems: packaging, assembly and interconnections, reliability performance, low-room temperature interfaces, heat transfer and refrigeration systems, device and system testing; 5) Applications: computer and telecommunications, space applications, infrared astronomy, instrumentation, low-temperature measurement systems. Abstract deadline, March 1, 1999. Suggestions and inquiries should be sent to W. D. Brown, The University of Arkansas, 3217 BELL, Fayetteville, AR 72701; telephone (501) 575-6045; telefax (501) 575-7967; wdb@engr.uark.edu.

RESOURCES

Information

New Books: Studies of High Temperature Superconductors: Advances in Research and Applications, edited by Anant Narlikar. Volume 24: Hg- Based High-Tc Superconductors -- Part II, includes the following topics -- the synthesis of mercury-based copper-oxide superconductors and their characteristics; x-ray single-crystal structure analysis of HgBa2Can- 1CunO2n+d (n = 1,5) homologous series; Hg-based superconducting filaments; Hg-Ba-Ca-Cu-O high-Tc thin films and superconducting quantum interference devices; synthesis and electron microscopic investigation of Hg and Tl/Pb-doped HTSC phases in bulk and thin-film forms; high- pressure synthesis and properties of HgBa2Can-1CunO2n+2+d, Y2Ba4Cu6+nO14+n, Sr1-xCaxCuO2, and Sr0.73CuO2 crystals; and high- pressure measurements on mercury cuprates. Publ. 1997; 244 pp.; price $89; ISBN 1-56072-517-6.

Volume 25: Chemistry and Related Aspects of High Temperature Superconductors, includes chapters containing the following topics: classification of superconducting oxides as interstitial alloys, reconciliation between structural features and descriptions of high-Tc superconductors, crystal structures and crystal chemistry of Bi- containing compounds in the Bi-Sr-Ca-Cu-O system, a review, studies on preparation and substitution of YBa2Cu4O8, crystal chemistry of the mercurocuprates, the synthesis and structure of HgBa2Can-1CunO2n+2+d, and mercury nonstoichiometry and copper valence in bulk Hg-1201. Publ. 1997; 331 pp.; price $81; ISBN 1-56072-518-4.

Contact Nova Science Publishers, Inc., 6080 Jericho Turnpike - Suite 207, Commack, NY 11725; telephone (516) 499-3103; telefax (516) 499- 3146; e-mail novasci1@aol.com.

More New Books: Materials Science in Microelectronics: Vol. 1 -- The Relationships Between Thin Film Processing and Structure, by E. S. Machlin. Contents are: deposition parameters, defect structure, grain structure, epitaxial structure, structure of amorphous films, stresses in thin films, and reaction-induced structure. Price $65; 240 pp.; ISBN 1-878857-07-X.

Vol. 2: The Effects of Structure on Properties in Thin Films, contains detailed discussions on the electrical, magnetic, optical, mechanical, mass transport, interface, and defect properties of thin films. Publ. 1998; 240 pp.; price $65; ISBN 1-878857-10-X.

Contact Giro Press, P.O. Box 203, Croton-on-Hudson, NY 10520; phone (914) 271-8924; fax (914) 271-6552.

Books: Advances in Cryogenic Engineering, Vol. 41, Part A & B, edited by Peter Kittel. These two volumes consist of 252 articles and treat all aspects of cryogenic engineering including cryobiology, cryofuels, cryocoolers, heat and mass transfer, large-scale systems, minesweeping with superconducting magnets, instrumentation and control, and safety issues. Publ. 1996; 2,036 pp.; price $235; ISBN 0-306-45300-2.

Advances in Cryogenic Engineering, Vol. 42, Part A & B, edited by Leonard T. Summers, presents 440 contributions addressing all aspects of cryogenic materials research. Topics include properties and processing of copper alloys, properties and applications of magnetic refrigerator materials, special low-temperature mechanical properties and phenomena, and innovations in other cryogenic systems. Publ. 1997; 1,522 pp.; price $306; ISBN 0-306-45374-6.

Contact Plenum Publishing Corporation, 233 Spring Street, New York, NY 10013-1578; telephone (800) 221-9369; telefax (212) 807-1047; e-mail info@plenum.com; Web site http://www/plenum.com.

Products and Services

YBCO thin films on lanthanumaluminate and sapphire substrates are available from PRIMA TEC, a small company that specializes in the production of YBCO films by the reactive thermal co-evaporation technique. Their PT3 system is able to coat an area of 6" diameter in one run. The company specializes in the fabrication of 500 nm thick YBCO films on 2" or 3" lanthanumaluminate and sapphire substrates. For information, contact PRIMA TEC, Technisches Entwerfen, Entwickeln und Handel GmbH & Superconductor Co KG, Schlossallee 28, D-85435 Erding, Germany; telephone +49 8122 5385; telefax +49 8122 5326; e-mail primatec@t-online.de.

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

In conjunction with the U.S. DOE Superconductivity Program for Electric Systems, the Oak Ridge National Laboratory (ORNL) has a postdoctoral research position available in the Fusion Energy Division. The basic function of this position is to conduct applied research and development activities to develop high-temperature superconductors (HTS) in electrical-system applications. Work involves ac loss measurements on prototype HTS tapes, coils, and cables; quench-protection studies of coils and cables made of HTS; and instrumentation and cryogenic design issues involved in the application of HTS to electrical power system devices such as transmission cables, motors, generators, and transformers. The ability to model the electrical and thermal- mechanical properties of these advanced components in electrical power applications is desirable. A Ph.D. in electrical engineering, physics, or a related discipline, or equivalent combination of education and experience is required. Experience in applied superconductivity, especially recent experience in electrical-engineering-related aspects of superconducting technology, is highly desirable. Familiarity with high-voltage/high-current electrical systems, superconducting coils, low-temperature experimental techniques, data-acquisition systems, superconducting material properties, cryogenic design and instrumentation procedures, and mechanical design analysis is desirable. Position is open to all qualified U.S. citizens and permanent residents. For further information contact M. J. Gouge at telephone (423) 576-4467; telefax (423) 576-7926; e-mail gougemj@ornl.gov; Web site http://www.ornl.gov/seer/research/HELP.html.

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, #6, March 15, 1998.