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 agjiduals.

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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: Happy anniversary to us! This issue marks the beginning of the twelfth year of publication of High-Tc Update. Our first issue was published May 1, 1987. That translates to 265 issues of the newsletter! In this time, the number of hard-copy subscribers have climbed to 1,000, electronic subscriber numbers have zoomed from about 300 in 1993 to 1,600 today, and we are receiving over 20,000 visits to the HTCU Web site every month! What does the future hold? We'll have to wait and see. Thank you for your support, encouragement--and preprints!

PrBa2Cu3O7-d

The properties of PrBa2Cu3O7-d (PBCO) have been of interest for some time because stoichiometric PBCO is the only antiferromagnetic insulator in the isostructural R-123 family of superconducting cuprates (Tc = 92 +- 2 K for RBa2Cu3O7-d, R = Y, La, and rare earths). Recently, however, evidence for superconductivity in specially prepared samples of PBCO has been found. A possible explanation of this superconductivity involves sample inhomogeneity: certain regions of the sample may be Ba-rich (Ba atoms replacing Pr on Pr sites), and in these regions the concentration of mobile Zhang-Rice singlet hole carriers may be raised above the threshold required for superconductivity.

To investigate the validity of this explanation, M. W. Pieper (Hamburg) et al. have used nuclear magnetic resonance of Pr and chain-site Cu to examine the nature of carriers doped in the CuO2 planes of Pr1+xBa2- xCu3O7 single crystals when x > 0 (Pr^+-123), x = 0 (Pr^0-123), and x < 0 (Pr^--123). From the different spectra in the solid solution, the authors found that the holes in Pr-rich crystals (Pr^+-123) are localized in states similar to those in stoichiometric samples (Pr^0- 123), i.e., in the 4f^2-2p[pi] hybridization band proposed by Fehrenbacher and Rice. In contrast, the spectra of crystals prepared under conditions favoring Ba-rich phases (Pr^--123) indicate the presence of mobile holes in Zhang-Rice singlets in the CuO2 plane. The authors' results thus support the model that superconductivity reported recently in Pr-123 crystals is due to Ba-rich regions in the inhomogeneous samples.

A preprint by W. L. Hults (Los Alamos) et al. reports the observation of superconductivity in some samples of polycrystalline PrBa2Cu3Ox. A sample that by x-ray diffraction showed 97% PrBa2Cu3Ox, 0.3% PrBaO3, and 2.3% BaCuO2 exhibited a small magnetically determined superconducting transition at 89 K and another transition at 12 K, each about 1% of the full Meissner fraction. The authors note that it is very difficult to fabricate the superconducting phase with appreciable probability, and that the material prefers to form in the insulating state.

Two preprints by H. A. Blackstead (Notre Dame) and J. D. Dow (Arizona State and NHMFL-Tallahassee) consider consequences of superconductivity in PrBa2Cu3O7 and argue that the primary superconducting condensate lies not in the CuO2 planes but rather in the charge-reservoir layers.

RBa2Cu3O7-d

Measurements by A. Hosseini et al. (UBC) of the surface impedance in YBa2Cu3O7-d show that the c-axis penetration depth and conductivity below Tc exhibit behavior different from that observed in the planes. The authors find that the c-axis penetration depth never has the linear temperature dependence seen in the ab plane, and instead of the conductivity peak in the planes, the c-axis microwave conductivity falls to low values in the superconducting state, then rises slightly below 20 K. According to the authors, these results show that c-axis transport remains incoherent below Tc, even though this is one of the least anisotropic cuprate superconductors.

A preprint by S. Kamal et al. (UBC) reports the growth of very high purity (99.995%) YBa2Cu3O7-d crystals in BaZrO3 crucibles and the measurement of Delta[lambda](T) and R_s(T) at 1 GHz in crystals with various oxygen treatments. For oxygen doping d = 0.007, Delta[lambda] and R_s essentially reproduce the authors' previous results and show no sign of the two order-parameter components recently reported by H. Srikanth et al. [ Phys. Rev. B 55, R14733 (1997)] on BaZrO3-grown crystals. For other oxygen concentrations, the authors in some cases have observed deviations from the linear low-T dependence of Delta[lambda], but never any sign of a second transition.

A numerical analysis of the effect of a rotating square YBa2Cu3O7-d crystal on the surrounding fluid flow in the pulling method has been performed by M. Egami (SRL-ISTEC and ISAS-Kanagawa) et al. The authors calculated the boundary-layer thickness and crystal growth rates for different rotation speeds.

Raman spectroscopy has been used by M. N. Iliev (TCSUH) to show that at the microscopic level the structure of YBa2Cu3Ox (6 < x < 7) compounds consists of coexisting domains of Ortho-I, Ortho-II, T, and T'-type oxygen ordering. Variation of x changes the relative weights of the domains and their contributions to the complex Raman spectra. In the overdoped case (7 < x < 8), the microstructure changes significantly as chain-oxygen atoms are shifted from their centrosymmetric sites and produce zig-zag chains instead of linear chains.

Bi Cuprates

A study of the Wohlleben effect (WE), the appearance of a paramagnetic moment of the sample when cooled in a constant magnetic field <0.5 Oe, also called the paramagnetic Meissner effect (PME), in powders of Bi2Sr2CaCu2O8+d (Bi-2212) consisting of isolated grains with dimensions d in the range 1 micrometer < d < 1 mm has been carried out by N. Knauf (Koeln) et al. The authors found that: (a) The WE was present in all powders studied, even for 1 micrometer grains. (b) The field-cooled and zero-field-cooled susceptibilities, as well as the microwave absorption (MWA), are strongly suppressed for d < 30-50 micrometers, probably because the grain size becomes smaller than the c-axis penetration depth. (c) In aligned powders, the WE is strongest for magnetic fields parallel to the c axis. The data give evidence that the WE is an intragrain property (i.e., it is not predominantly determined by intergrain weak links) and that the spontaneous currents flow within the ab planes. The presence of the WE in 1 micrometer grains requires that the critical current density of the pi contacts, which are generally assumed to explain the spontaneous currents, must be of order 10^5-10^6 A/cm^2, even close to Tc.

A preprint by Y. S. Sudershan (IIS-Bangalore) et al. reports a study of the isothermal magnetic field-dependent rf power dissipation P(H) for H||c and H_[rf]||a in the superconducting state of Bi2Sr2CaCu2O8+d (Bi- 2212) single crystals before and after irradiation with 250 MeV [107]^Ag^[17+] ions, which produces amorphous columnar defects. The authors observe a change in the behavior of P(H) upon irradiation, and they attribute this change to the strong enhancement of the vortex tilt modulus c_[44] when the pancake vortices in adjacent CuO2 bilayers are pinned within the columnar defects. The authors also observed that the rf dissipation disappears below 69 K, the temperature at which the vortex core diameter becomes equal to the columnar defect diameter.

A related paper by Y. S. Sudershan (IIS-Bangalore) et al. reports measurements of the magnetic field-dependent rf (20 MHz) power dissipation P(H) vs. H for H_[rf]||H||c in Bi2Sr2CaCu2O8+d (Bi-2212) single crystals. The magnetic field dependence shows an onset at 102 K, well above the nominal Tc ~ 82 K. The authors attribute this effect to superconducting fluctuations.

The development of a cryogenic deformation technique that improves the critical current density Jc of silver-sheathed (Bi,Pb)2Sr2Ca2Cu3O10+d [(Bi,Pb)-2223] superconducting tapes is reported in papers by Y. C. Guo (Wollongong) et al. and S. X. Dou et al. (Wollongong). A typical cryogenic deformation process involves rolling or pressing the wires into tapes at 77 K and then heat treating the tapes at 838-842^oC for a period of 40-60 h. The authors found that the cryogenic deformation improves the density, grain alignment, Ag/oxide core interfacial area, and hence the critical current density.

According to a preprint by N. D. Zhigadlo (Minsk) et al., the addition of Cs to Bi1.7Pb0.3Sr2Ca2Cu3O10+d [(Bi,Pb)-2223] is effective in forming the high-Tc phase and enhancing the superconducting properties. A preprint by H. Maeda (Tohoku and NRIM) et al. reports that V doping of (Bi,Pb)-2223 enhances the 2223 phase formation without degradation of Tc and leads to increased Jc.

Other Cuprates

As reported by G. Balestrino et al. (Roma), (CaCuO2)m/(BaCuO2)n and (SrCuO2)m/(BaCuO2)n superlattices with good crystallographic quality can be engineered by pulsed laser deposition over a wide range of compositions for n = 2 and 1 <= m <= 6. The authors report, however, that the Sr- and Ca-based superlattices have qualitatively different electrical transport properties. Superconductivity is found only for the Ca-containing superlattices. The resistivity of the Ca-containing superlattices grown at high oxygen pressure (>0.2 mbar) was found to be metallic with a full transition to a superconducting state at temperatures as high as 70 K (zero-resistance transition temperature). The authors note that while this value of Tc is the highest yet reported for an artificial structure, it is still lower than that of the related CuBa2Can-1CunOx compounds (Tc = 116 K) obtained by high-pressure synthesis.

Electronic Raman scattering measurements are reported by A. Sacuto (ENS- Paris) et al. for HgBa2Ca2Cu3O8+d (Hg-1223) single crystals in the superconducting state. Pure electronic Raman spectra with no phonon structures hindering the analysis of the electronic continuum were obtained. Below Tc, two electronic structures at 2[Delta] ~~ 6.4 k_BTc and 2[Delta] ~~ 9.4 k_BTc were seen. Both were observed simultaneously in pure A_[1g] symmetry, the one with higher energy being located at the energy of the B_[1g] maximum. The two maxima do not soften significantly as the temperature is raised up to Tc, but they disappear at and above Tc. The low-energy frequency dependence of the B_[1g] electronic response is linear for various excitation lines in the 476.5 to 647.1 nm range. The authors assert that such experimental data cannot be reconciled with pure d_[x^2-y^2] symmetry. Instead, the data favor an anisotropic superconducting gap with two distinct gap maxima and nodes existing outside the [110] and [110] directions in k space. The authors discuss the simplest model order parameter that is compatible with their experimental findings.

Vortices

The first-order vortex-lattice phase transition has been observed by T. Sasagawa et al. (Tokyo) in (La1-xSrx)2CuO4 (LSCO) single crystals (0.046 <= x <= 0.077). A scaling law, H_[pt](T) = 2.85 gamma^[-2]s^[-1](Tc/T - 1) Oe, was found to hold for the phase transition lines not only in this system but also in YBa2Cu3O7-d (Y-123) and Bi2Sr2CaCu2O8+d (Bi-2212) for fields H||c. Here, gamma^2 = m_c/m_[ab] is the anisotropy factor, and s is the superconducting layer spacing: s = 6.6 Angstroms, 11.7 Angstroms, and 15.4 Angstroms for LSCO, Y-123, and Bi-2212, respectively. The authors assert that this form of scaling provides strong evidence that the first-order phase transition in high-Tc superconductors manifests itself as vortex-lattice sublimation, rather than melting. In other words, at fields and temperatures above the phase transition, the vortex lines split up into a pancake-vortex gas with no correlation between pancake vortices along the c direction.

The resistive transitions into a glassy vortex state in oxygen-deficient YBa2Cu3O7-d twinned single crystals of varying anisotropy gamma (8.7 <= gamma <= 35) have been studied by B. Lundqvist et al. (Royal Institute of Technology, Stockholm) with an applied magnetic field along the c axis. For B >= 1 T, the authors found the glass line to be well described by the empirical relation B_g = B_0[(1 - T/Tc)/(T/Tc)]^[alpha], where alpha ~~ 1 and B_0 ~~ 1.85 phi_0/(gammas)^2. The values obtained for five single crystals were alpha = 1.21, Tc = 91.3 K, and gamma = 8.7; alpha = 1.05, Tc = 86.2 K, and gamma = 13; alpha = 0.98, Tc = 73.2 K, and gamma = 19; alpha = 1.06, Tc = 62.2 K, and gamma = 28; and alpha = 1.27, Tc = 51.8 K, and gamma = 35. The authors also found good fits to data on thin films of Tl-2212 (alpha = 1.59 and 1.82) and Bi-2223 (alpha = 1.82).

By applying a Lindemann-like criterion used previously by Kierfeld et al. [Phys. Rev. B 55, 626 (1997)], J. Kierfeld (Koeln) has estimated the magnetic field and temperature at which a topologically ordered vortex- glass phase in a high-Tc superconductor becomes unstable to disorder- induced formation of dislocations. The author shows that the criterion used is equivalent to a conventional phenomenological Lindemann criterion, including values of the numerical factors, such as the Lindemann number c_L.

A model of the effective interaction between 2D pancake vortices in layered superconductors has been derived by Z.-X. Cai (Brookhaven) et al. using the Lawrence-Doniach model. The authors show that the intralayer interaction energy of the logarithmically interacting pancake vortices can be evaluated analytically with the help of the Ewald summation technique. Using Langevin dynamics simulations, the authors evaluated the isothermal shear modulus c_[66] of flux-line lattices for various values of the interlayer coupling strength.

The vortex response to various ac drives has been studied by V. Metlushko (Argonne) et al. in high-quality YBa2Cu4O8 single crystals. Well within the vortex solid phase, the authors observed a re-entrant resistive state, characterized by long relaxation times. The pulsed- current response and I-V characteristics reveal that in this state the driven vortex system relaxes in such a way as to increase the effective pinning force. The authors propose a phenomenological model to account for the observed features, in particular the clockwise hysteresis of the I-V curves and the increase of the apparent critical current with applied current amplitude.

The stability of the square vortex lattice, which recently has been observed in experiments on the borocarbide superconductors, has been investigated theoretically by K. Park and D. A. Huse (Princeton). To take into account the tetragonal symmetry, the authors added four-fold symmetric fourth-derivative terms to the Ginzburg-Landau free energy. The authors used nonperturbative numerical calculations to locate the boundary in the H-T phase diagram between the distorted hexagonal and square vortex lattices.

Thin Films

An extensive study of the optimal oxygenation of YSr2Cu2.75Mo0.25Oz thin films has been carried out by J. P. Sydow et al. (Cornell). The authors found that optimization of oxygen content can be accomplished globally by ozone anneals at 1 atm and locally by electromigration of chain- oxygen vacancies out of thin-film microbridges. Both techniques lead to a maximal Tc = 75 K, substantially higher than has been achieved previously in this material.

In principle, magneto-optical investigations of flux penetration into type-II superconductors allow the determination of the local critical current density J by inversion of the Biot-Savart law. Because of the computational effort, however, this method has been limited to relatively low spatial resolution of the current density. Using fast Fourier transforms, Ch. Jooss et al. (MPI-Stuttgart) have developed a fast inversion scheme that images the current distribution in the entire sample with high spatial resolution. The authors demonstrate the power of their method by imaging the local current density in a YBa2Cu3O7-d square and in a disk in increasing and decreasing external magnetic fields. The authors also image the perturbations of the local current density near macroscopic defects in a square and a disk.

A paper by K. Fujino et al. (Sumitomo) reports the investigation of double-sided deposition of large-area YBa2Cu3O7-d thin films. The authors used pulsed laser deposition equipment with an off-axis geometry to deposit films on LaAlO3 substrates with a diameter of 3 in. The resulting films exhibited 77.3 K Jc's in excess of 10^6 A/cm^2 over the entire area of the double-sided film.

Spectroscopic ellipsometry has been used by M. E. Bijlsma et al. (Twente) to do in-situ investigations of the optical properties of high- quality YBa2Cu3O6 thin films deposited by off-axis magnetron sputtering. The optical transitions at 4 eV of films that were not exposed to the atmosphere were found to have a magnitude that is twice as high as previously reported and to be described by a single Lorentz oscillator throughout the temperature range 20-700^oC.

Measurements of the critical temperature of YBCO/YBa2Cu3-xCoxO7+d superconductor/normal bilayer films are reported by E. Polturak (Technion) et al. The authors found that, depending on the morphology of the S-N interface, the coupling between S and N layers can be turned up to depress the Tc of S by tens of degrees, or turned down so that the layers appear to be almost completely decoupled. This novel effect can be explained by the mechanism of quasiparticle transmission into an anisotropic superconductor.

Electron-beam irradiation has been used by F. Tafuri (Napoli) et al. to produce controllable variations in the properties of YBa2Cu3O7-d biepitaxial grain-boundary Josephson junctions. The authors found that electron irradiation changes the current-voltage (I-V) characteristics by modifying the oxygen content in the vicinity of the grain boundaries.

The electrical transport properties of symmetrical [001] tilt Nd1.85Ce0.15CuO4-y bicrystal grain-boundary Josephson junctions fabricated on SrTiO3 bicrystal substrates with misorientation angles of 24 degrees and 36.8 degrees have been studied by S. Kleefisch (Koeln) et al. The authors found that the superconducting properties of these junctions are very similar to those of grain-boundary junctions fabricated from hole-doped high-temperature superconductors. This suggests that the symmetry of the order parameter, which most likely is different for the electron- and hole-doped high-temperature superconductors, has little influence on the characteristic properties of the symmetrical [001] tilt grain-boundary Josephson junctions.

Two papers by R. N. Bhattacharya (NREL) et al. report on the properties of electrodeposited (ED) TlBa2Ca2Cu3O9 (Tl-1223) films. One of these reports Jc(77K,0T) above 1.6 x 10^5 A/cm^2 for strongly biaxially textured Tl-1223 films electrodeposited on Ag-coated single-crystal LaAlO3. The authors suggest that electrodeposition offers a promising and economic approach for fabricating superconducting wire or tape, and they project costs upon scale-up at or below $10/kAm for an ED-based Tl- oxide tape process.

As reported by W. N. Kang (Kansas and TCSUH) et al., mixed-state Hall- effect measurements of HgBa2CaCu2O6+d (Hg-1212) thin films after radiation with high-energy Xe ions reveal that the Hall scaling exponent beta in rho_[xy] = A[rho_[xx]^[beta] not only increases from 1.0+-0.1 to 2.0+-0.05 with increasing fields up to 8 T, but also increases from 1.0+-0.1 to 1.5+-0.05 as the angle between the columnar tracks and the magnetic field of 4 T decreases from 75 degrees to 0 degrees. The observation of beta = 1 is consistent with a recent theory based on d- wave superconductivity [N. B. Kopnin and G. E. Volovik, Phys. Rev. Lett. 79, 1377 (1997)], where it is predicted that the Hall angle has a universal behavior independent of the mean-free path in the low-field region.

The thermal peeling stress in a thin high-Tc superconducting film resulting from the temperature decrease from high processing temperatures to cryogenic operating temperatures has been calculated by B. Gu and P. E. Phelan (Arizona State) using finite element analysis. The method reveals a stress singularity at the very edge of the film that is not predicted by analytical calculations.

Intrinsic Josephson Junctions

A paper by K. Schlenga (Erlangen-Nuernberg) et al. presents a detailed discussion of the current-voltage characteristics of intrinsic Josephson junctions in Bi2Sr2CaCu2O8+d (Bi-2212) and Tl2Ba2Ca2Cu3O10 (Tl-2223). In these materials, Josephson tunnel junctions are formed naturally between adjacent superconducting CuO2 bilayers or trilayers. The current-voltage characteristics of every individual junction exhibits pronounced structures in the subgap regime. These structures are best explained by a recently proposed resonant coupling mechanism between infrared active optical c-axis phonons and oscillating Josephson currents.

The collective switching of stacked intrinsic Josephson junctions in the current-voltage characteristics of (Bi,Pb)2Sr2Ca2Cu3O10+d [(Bi,Pb)-2223] thin films has been studied by M. Sakai et al. (Matsushita Electric). In a current-biased measurement, collective switching has been observed, while in a voltage-biased measurement, clear branching structure has been observed. The authors explain these effects by taking effective heat diffusion into account.

Applications

The properties of YBCO/SrTiO3 thin-film K-band tunable bandpass filters on LaAlO3 substrates are reported by G. Subramanyam (Northern Iowa) et al. The two-pole filters were designed for a center frequency of 19 GHz and 4% bandwidth. Tunability is achieved through the nonlinear dc electric field dependence of the relative dielectric constant of SrTiO3. Center frequency shifts of more than 2 GHz were obtained at a 400 V bipolar dc bias at temperatures below 77 K, with minimal degradation in the insertion loss of the filters.

The operation and testing of a high-temperature superconducting (HTS) high-gradient magnetic separator (HGMS) are reported by J. A. Selvaggi (Eriez Magnetics) et al. The separator magnet is made of 624 m of Ag/Bi-2223 wire and has overall dimensions of 18 cm OD, 15.5 cm height, and 5 cm ID. HTS current leads are used to reduce the heat leak to the magnet. The system operates in a vacuum and is cooled by a two-stage Gifford-McMahon cryocooler. HGMS experiments were performed using this system to demonstrate the performance of HTS magnetic separators.

Theory

A new method for calculating the free energy of an inhomogeneous superconductor has been developed by I. Kosztin (Illinois-Urbana and Chicago) et al. The method is based on the quasiclassical limit (or Andreev approximation) of the Bogoliubov-de Gennes (or wave-function) formulation of the theory of weakly coupled superconductors. The method is applicable to any pure bulk superconductor described by a pair potential with arbitrary spatial dependence in the presence of supercurrents and an external magnetic field. The local density of states and the free-energy density of an inhomogeneous superconductor can be expressed in terms of the diagonal resolvent of the corresponding Andreev Hamiltonian, which obeys the Gelfand-Dikii equation. The authors point out the connection between this approach and the well- known Eilenberger equations for the quasiclassical Green's function. The results are used to construct a general algorithm for calculating the gauge-invariant gradient expansion of the free-energy density of an inhomogeneous superconductor at arbitrary temperatures.

A new parameterization of the Eilenberger equations of superconductivity in terms of solutions of a scalar differential equation of the Riccati type has been found by N. Schopohl (Tuebingen). The author shows that the quasiclassical propagator and the local density of states may be reconstructed, without explicit knowledge of any eigenfunctions or eigenvalues, by solving a simple initial-value problem for the linearized Bogoliubov-de Gennes equations. The Riccati parameterization of the quasiclassical propagator leads to a stable and fast numerical method for solving the Eilenberger equations.

The anomalous proximity effect between a d-wave superconductor and a surface layer with small electronic mean free path has been studied theoretically by A. A. Golubov (Twente and ISSP-Chernogolovka) and M. Yu. Kupriyanov (Twente and Moscow State). The authors calculate the angular and spatial structure of the pair potential and the quasiclassical propagators in the interface region self-consistently. The authors find that an isotropic gapless superconducting state is induced in the disordered layer.

The effect of nonmagnetic impurities in the superconducting state of the t-J model has been studied by H. Tanaka (Kobe) et al. The authors derived the Bogoliubov-de Gennes equation using a slave-boson mean-field approximation and solved it numerically at T = 0. The d_[x^2-y^2] order parameter is suppressed near an impurity, and its spatial variation induces an extended s-wave component. The authors also find a local charge-density-wave-like feature due to Friedel oscillations, and this leads to a splitting of the expected zero-energy Andreev bound state. Because the zero-energy state is removed, a transition to a state that violates time-reversal symmetry or produces antiferromagnetic order is unlikely to occur.

A preprint by I. Zutic and O. T. Valls (Minnesota) considers an unconventional superconductor in a low-frequency harmonic magnetic field. In the Meissner regime at low temperatures, a nonlinear magnetic response arises from quasiparticle excitations near minima in the energy gap. As a consequence, various physical quantities acquire higher harmonics of the frequency of the applied ac field. The authors discuss how examination of the field and angular dependence of these harmonics allows determination of the structure of the energy gap. In particular, the authors show how to distinguish nodes from small finite minima (quasinodes).

As shown by T. V. Ramakrishnan (IIS-Bangalore), the interaction between planar quasiparticles in a d_[x^2-y^2] superconductor and quantized vortices associated with a magnetic field perpendicular to the plane induces a pair potential with d_[xy] symmetry, out of phase with the d_[x^2-y^2] order. The author argues that the resulting fully gapped state may be the high-field, low-temperature phase observed by K. Krishana et al. [Science 277, 83 (1997)] in magnetothermal conductivity measurements in superconducting single-crystal Bi-2212.

A phase diagram for a quasi-2D metal with variable carrier density has been derived by V. M. Loktev (Kiev) et al. The phases present are the normal phase where the order parameter is zero, the pseudogap phase where the absolute value of the order parameter is nonzero but its phase is random, and two superconducting phases. One of these is the quasi-2D Berezinskii-Kosterlitz-Thouless phase, and the other is a phase with long-range order.

Pairing effects in the edge states of paired fractional quantum Hall states have been studied by K. Ino (ISSP-Tokyo) using persistent edge currents as a probe. The author finds that the currents are flux periodic with period hc/e at higher temperatures but that anomalous oscillations develop at low temperatures, converging to a sawtooth function with period hc/2e at zero temperature, indicating pair condensation.

A macroscopic Coulomb blockade model of density-wave transport has been developed by J. H. Miller, Jr. (TCSUH). In this model, an electric field E induces the creation, by quantum tunneling, of pairs of oppositely charged solitons and antisolitons in a density wave. The author suggests that some aspects of the theory may apply to tunneling of vortices in superconductors and long Josephson junctions.

Other Activities

The interference of proximity-induced superconducting correlations in mesoscopic metallic rings is sensitive to the magnetic flux phi inside these rings. This is the reason for magnetoconductance oscillations in such systems. Using devices with superconducting Al and normal Ag elements, V. N. Antonov (NTT) et al. have detected experimentally and explained theoretically a novel effect: The phase of these oscillations can switch between 0 and pi depending on the resistance of intermetallic interfaces and temperature. The effect is due to a nontrivial interplay between the proximity-induced enhancement of the local conductivity and the proximity-induced suppression of the density of states at low energies.

Overview

A book chapter by A. Hoffmann (UCSD-La Jolla) et al. discusses persistent photoconductivity. Upon illumination, underdoped YBa2Cu3O7- d, for example, shows a decrease of resistivity and an increase of Tc. The photoinduced changes are persistent at low temperatures but relax at room temperature. A possible explanation is that electrons of photoinduced electron-hole pairs are trapped at localized states spatially separated from the conduction layer. The authors recently observed persistent photoconductivity in Tl2Ba2CuO6+d (Tl-2201) and Y- doped Bi2Sr2CuO6 (Bi-2201), which suggests that persistent photoconductivity might be a common phenomenon in high-Tc superconductors (37 refs.).

Ph.D. Theses

The Stuttgart Ph.D. thesis of B. Lederle reports theoretical and experimental determinations of the phonon Raman scattering efficiency of several high-Tc superconductors. Included are studies of YBa2Cu3O7-d, YBa2Cu4O8, Y2Ba4Cu7O15-d, PrBa2Cu3O7-d, and Ba1-xKxBiO3. The thesis contains Raman measurements of the absolute scattering efficiencies of all c-polarized phonons vs. laser frequency, and comparisons with extensive LMTO-ASA band-structure calculations of the corresponding Raman tensors. The author was able to observe interference effects between the complex components of the Raman tensors for polarizations that are off the crystal axes (208 refs.).

A thorough investigation of crystal-field effects in the f-electrons of Nd and other rare-earth-based 123 and 214 cuprates is described in the Ph.D. thesis of T. Strach (Stuttgart). Special attention is given to the interaction of phonons with crystal-field f-levels. Having determined the eigenvectors of the 115 cm^[-1] and 150 cm^[-1] phonons of 123 materials by isotopic substitution, the author discusses the results theoretically (209 refs.).

The Jena Ph.D. thesis of G. Kaiser (Dresden) reports the results of theoretical and experimental investigations of the conditions for successful operation of high-temperature superconducting (HTS) sensors with small-scale closed-cycle cryocoolers. The author introduces models to describe the influence of cryocooler disturbances on HTS dc SQUID magnetometers, gradiometers, bolometers, and double bolometers, and reports measurements of these disturbances (134 refs.).

Contributed by John R. Clem

Contents: Technology News is on page 7; Preprints begin on page 7; and Coming Events begin on page 14.

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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.

Using the PIT (powder-in-tube) technology, Alcatel Cable (France) have successfully produced 1000 meters of Bi-based superconducting wire with current densities that exceed 200 A/mm2 at liquid-nitrogen temperatures. The production of this wire is the first step towards the construction of high magnetic field coils. Eventually the company plans to use the wires for superconducting power cables. For further information, contact Wendy Wilmouth, Alcatel Cable France, S.A. 30, rue Pierre Beregovoy, BP 309, F-92111 Clichy Cedex, France; telephone +33 1 47 56 66 20; telefax +33 1 47 56 69 24; e-mail wendy.wilmouth@ accyd.alcatel.fr.

A key player in the development of wireless communications filter products utilizing superconducting materials and cryogenic technologies, Superconductor Technologies Inc. (STI) recently announced that it has scheduled field trials of its SuperFilter [TM] system with more than 20 different wireless carriers, which include eight of the top ten cellular service providers in the U.S. These trials will be conducted at more than twenty-five cell sites during the next four months. STI also announced that it had received orders for fifteen SuperFilter [TM] systems in the first quarter of 1998, giving it a backlog of twenty- three systems at quarter end, the majority of which will be shipped during the second quarter of 1998. Additionally, revenues for commercial products for the first quarter of 1998 are expected to exceed commercial revenues realized during the entire year of 1997. According to officials at STI, interest by carriers in superconducting filter technology is increasing rapidly as customers see more evidence of its capabilities to solve problems of range and call quality that are becoming more important as competition increases. For information, contact Superconductor Technologies Inc., 460-F Ward Drive, Santa Barbara, CA 93111-2310; telephone (805) 683-7646; telefax (805) 967- 0342; e-mail info@suptech.com.

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.

V. N. Antonov, H. Takayanagi, F. K. Wilhelm, and A. D. Zaikin, "pi- Shifted Magnetoconductance Oscillations in Mesoscopic Superconducting- Normal Heterostructures." Submitted to Phys. Rev. Lett. NTT Basic Research Laboratories, 3-1 Morinosato Wakamiya, Atsugi-shi, Kanagawa 243-01, JAPAN; F. K. Wilhelm's telephone at Universitaet Karlsruhe +49 721 608 3370; telefax +49 721 69 8150; e-mail wilhelm@tfp.physik.uni- karlsruhe.de; preprint also available at cond-mat@xxx.lanl.gov (#9803339).

R. Auer, E. Brecht, K. Herrmann, and R. Schneider, "Anisotropic Electric Field Effect in YBa2Cu3O7-x Thin Films Grown on (110) SrTiO3 Substrates." To be published in Physica C (in press). Contact R. Schneider, Forschungszentrum Karlsruhe, Institut fuer Nukleare Festkoerperphysik, P.O. Box 3640, D-76021 Karlsruhe, GERMANY; telephone +49 7247 82 4381; telefax +49 7247 82 4624; e-mail rudolf.schneider@infp.fzk.de. Key words: high-Tc films, dielectric thin films, laser deposition, superconducting devices. 74.72.-h; 77.55.+f; 81.15.Fg; 85.25.-j.

G. Balestrino, S. Martellucci, P. G. Medaglia, A. Paoletti, and G. Petrocelli, "Growth, Structural and Electrical Characterization of [(Ca,Sr)CuO2]m/[BaCuO2]n Superlattices." To be published in Physica C. INFM-Dipartimento di Scienze e Tecnologie Fisiche ed Energetiche, Universita di Roma "Tor Vergata," via di Tor Vergata, I-00133 Rome, ITALY. 74.80.Dm; 81.15.Fg; 68.65.+g.

R. N. Bhattacharya, R. D. Blaugher, Z. F. Ren, W. Li, J. H. Wang, M. Paranthaman, D. T. Verebelyi, and D. K. Christen, "Superconducting Epitaxial Thallium Oxide Films." Submitted to Appl. Phys. Lett. National Renewable Energy Laboratory, 1617 Cole Boulevard, Golden, CO 80401-3393; telephone (303) 275-3000.

R. N. Bhattacharya, R. D. Blaugher, Z. F. Ren, W. Li, J. H. Wang, M. Paranthaman, D. T. Verebelyi, and D. K. Christen, "Superconducting Thallium Oxide Films by the Electrodeposition Method." Submitted to Physica C. National Renewable Energy Laboratory, 1617 Cole Boulevard, Golden, CO 80401-3393; telephone (303) 275-3000. Key words: thick film, electrodeposition, Tl oxides.

Marcel E. Bijlsma, Herbert Wormeester, Dave H.A. Blank, Edward Span, Arend van Silfhout, and Horst Rogalla, "The Temperature Dependence of the 4 eV Optical Transition in YBa2Cu3O6." To be published in Phys. Rev. B. Contact Herbert Wormeester, Department of Applied Physics, Centre for Materials Research, University of Twente, P.O. Box 217, 7500 AE, Enschede, THE NETHERLANDS; e-mail h.wormeester@tn.utwente.nl. 78.66.Li; 74.25.Gz.

Howard A. Blackstead and John D. Dow, "Consequences of Superconductivity in PrBa2Cu3O7." Manuscript #Florence SVI-2:L02; to be published in the Proc. of the 9th CIMTEC World Ceramic Congress and Forum on New Mater., Florence, Italy, June 14-19, 1998, edited by P. Vincenzini (Techna Publishers, Faenza, Italy, 1998). Department of Physics, University of Notre Dame, Notre Dame, IN 46556; telephone (219) 631-7078; telefax (219) 631-5952; e-mail blackstd@rems1.phys.nd.edu. Key words: superconductivity, PrBa2Cu3O7. 74.20.Fg.

Howard A. Blackstead and John D. Dow, "Superconductivity in PrBa2Cu3O7: Implications." To be published in Int. J. Mod. Phys. B. Department of Physics, University of Notre Dame, Notre Dame, IN 46556; telephone (219) 631-7078; telefax (219) 631-5952; e-mail blackstd@rems1.phys.nd.edu.

Howard A. Blackstead, John D. Dow, Israel Felner, H. Luo, David B. Pulling, and W. B. Yelon, "Evidence of Granular Superconductivity in Pr2-zCezSr2Cu2NbO10." To be published in Int. J. Mod. Phys. B. Department of Physics, University of Notre Dame, Notre Dame, IN 46556; telephone (219) 631-7078; telefax (219) 631-5952; e-mail blackstd@rems1.phys.nd.edu.

J. Borgmann, P. David, H. J. Krause, R. Otto, and A. I. Braginski, "Compensation Techniques for HTS-rf-SQUID Magnetometers Operating in Unshielded Environments." To be published in Appl. Supercond. (in press). Institut fuer Strahlen- und Kernphysik der Universitaet Bonn, D-53117 Bonn, GERMANY.

Zhi-Xiong Cai, Girija Dubey, and David O. Welch, "Numerical Simulations of Flux-Line Lattices in Layered Superconductors." To be published in Physica C (in press). Department of Applied Science, Bldg. 480, Brookhaven National Laboratory, P.O. Box 5000, Upton, NY 11973. Key words: flux lines, Lawrence-Doniach model, c_[66]. 74.60.Ge; 74.72.Hs.

A. Canesi, M. R. Cimberle, C. Ferdeghini, A. Diaspro, P. Guasconi, S. Gariglio, D. Marre, M. Putti, A. S. Siri, F. Canepa, P. Manfrinetti, and A. Palenzona, "In Situ Deposition of ErNi2B2C Films by Pulsed Laser Ablation Technique." To be published in Physica C (in press). Contact C. Ferdeghini, INFM/CNR-Dipartimento di Fisica, Universita di Genova, Via Dodecaneso 33, I-16146 Genova, ITALY. Key words: thin films, upper critical field Hc2, magnetoresistance, antiferromagnetic order, scanning tunnel microscopy.

Wu Ming Chen, S. S. Jiang, Y. C. Guo, J. R. Jin, X. S. Wu, X. H. Wang, X. Jin, X. N. Xu, X. X. Yao, and S. X. Dou, "Effects of Low-Energy Neutron Irradiation on Bi-Based Superconductors." To be published in Physica C (in press). Department of Physics and National Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093, PEOPLE'S REPUBLIC OF CHINA; telefax +86 25 3302728. Key words: low- energy neutron irradiation, superconductor, Sn doped.

A. N. Das and S. Sil, "Restricted Pair Tunneling Model in the Context of High-Tc Cuprates." To be published in Physica C (in press). Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Calcutta 700 064, INDIA. Key words: pair tunneling, cuprates, single-particle hopping. 74.20.- z; 74.62.-c; 74.62.Dh.

S. X. Dou, Q. Y. Hu, Y. C. Guo, J. Horvat, and H. K. Liu, "Cryogenic Deformation Process of High Temperature Superconductors." Centre for Superconducting and Electronic Materials, University of Wollongong, Wollongong NSW 2522, AUSTRALIA; telephone +61 2 4221 5730; telefax +61 2 4221 5731; e-mail shi_dou.uow.edu.au.

M. Egami, K. Kuwahara, and Y. Shiohara, "Numerical Analysis of Fluid Flow of Rotating Squared Crystal in the Pulling Method and Its Effect on Growth Shape." 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.

H. Faqir, O. Monnereau, H. Chiba, M. Kikuchi, and Y. Syono, "Crystal Growth in Bi-Sr-Ca-Cu-O System." To be published in Appl. Supercond. (in press). Institute for Materials Research, Tohoku University, Katahira 2-1-1, Aoba-ku, Sendai 980, JAPAN; telephone +81-22-227-6200; telefax +81-22-264-7984.

Koso Fujino, Masaya Konishi, and Ken-ichi Sato, "Large Area Y1Ba2Cu3O7-d Thin Film on LaAlO3 Substrate Deposited by Pulsed Laser Deposition." To be published in Appl. Supercond. (in press). Basic High-Technology Laboratories, Sumitomo Electric Industries, 1-1-3 Shimaya, Konohana-ku, Osaka 554, JAPAN; telefax +81 6 466 5704; e-mail fujino@okk.sei.co.jp.

K. Fuelber, A. Geerkens, S. Ewert, and K. Winzer, "Magnetostriction Due to Flux Pinning in Polycrystalline YNi2B2C." To be published in Physica C (in press). Lehrstuhl Experimentalphysik, Brandenburg Technical University of Cottbus, P.O. Box 101344, D-03013 Cottbus, GERMANY; telephone +49 355 69 2483; telefax +49 355 69 2312; e-mail sigma@e- physik.tu-cottbus.de. Key words: borocarbides (YNi2B2C), magnetostriction, flux pinning, critical current density. 74.72.Ny; 74.60.Ec; 74.60.Ge; 74.60.Jg; 75.80.+q.

F. Furuta, E. Oya, S. Matsumoto, H. Akaike, A. Fujimaki, and H. Hayakawa, "Logic Function Demonstrations of 4JC-SQUID-Based Gates." To be published in Appl. Supercond. (in press). Department of Quantum Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-01, JAPAN.

A. A. Golubov and M. Yu. Kupriyanov, "Anomalous Proximity Effect in d- Wave Superconductors." Submitted to Phys. Rev. B. Department of Applied Physics, University of Twente, P.O. Box 217, 7500 AE Enschede, THE NETHERLANDS; e-mail a.golubov@tn.utwente.nl; preprint also available at cond-mat@xxx.lanl.gov (#9803369). 74.50.+r; 74.72.-h.

E. Goodilin, A. Oka, J. G. Wen, Y. Shiohara, M. Kambara, and T. Umeda, "Twins and Related Morphology of As-Grown Neodymium-Rich Nd1+xBa2-xCu3Oz Crystals." To be published in Physica C (in press). Superconductivity Research Laboratory, International Superconductivity Technology Center (ISTEC), 10-13 Shinonome 1-chome, Koto-ku, Tokyo 135, JAPAN; telefax +81 3 3536-5714; e-mail john@istec.or.jp. Key words: neodymium-rich solid solution, phase relations, twinning.

I. Grosu, I. Tifrea, and M. Crisan, "Superconductivity and Critical Coupling in Non-Fermi Liquids." To be published in J. Supercond. Department of Physics, University of Cluj, 3400 Cluj, ROMANIA.

Bei Gu and Patrick E. Phelan, "Thermal Peeling Stress Analysis of Thin- Film High-Tc Superconductors." To be published in Appl. Supercond. (in press). Contact Patrick E. Phelan, Department of Mechanical and Aerospace Engineering, Arizona State University, P.O. Box 876106, Tempe, AZ 85287-6106.

Y. C. Guo, J. Horvat, H. K. Liu, and S. X. Dou, "On the Role of Bi2Sr2Ca1Cu2O8 and Bi2Sr2Cu1O6 on the Weak Links and Critical Currents in (Bi,Pb)2Sr2Ca2Cu3O10/Ag Superconducting Tapes." To be published in Appl. Supercond. (in press). First Research Group, National Research Institute for Metals, 1-2-1 Sengen, Tsukuba, Ibaraki 305, JAPAN; telefax +81 298 59 2301; e-mail ycguo@nrim.go.jp.

Y. C. Guo, J. X. Jin, H. K. Liu, Y. Tanaka, and S. X. Dou, "Long Lengths of Silver-Clad Bi2223 Superconducting Tapes with High Current-Carrying Capacity." To be published in Appl. Supercond. (in press). First Research Group, National Research Institute for Metals, 1-2-1 Sengen, Tsukuba, Ibaraki 305, JAPAN; telefax +81 298 59 2301; e-mail ycguo@nrim.go.jp.

Y. C. Guo, H. K. Liu, X. Z. Liao, and S. X. Dou, "Improving the Current- Carrying Capacity of Silver Sheathed (Bi,Pb)2Sr2Ca2Cu3O10 Superconductors by Cryogenic Deformation." To be published in Physica C. First Research Group, National Research Institute for Metals, 1-2-1 Sengen, Tsukuba, Ibaraki 305, JAPAN; telefax +81 298 59 2301; e-mail ycguo@nrim.go.jp. Key words: (Bi,Pb)2Sr2Ca2Cu3O10, cryogenic deformation, critical current, microstructure.

Axel Hoffmann, Z. F. Ren, J. Y. Lao, J. H. Wang, D. Girata, W. Lopera, P. Prieto, and Ivan K. Schuller, "Persistent Photoconductivity in High- Tc Superconductors." To be published in Application of Spectroscopy to Supercond. Mater., ACS Symp. Series, edited by E. Faulques, (ACS Publications, Washington, DC). Department of Physics 0350, University of California at San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0350; e-mail hoffmann@ucsd.edu.

A. Hosseini, Saeid Kamal, D. A. Bonn, Ruixing Liang, and W. N. Hardy, "c-Axis Electrodynamics of YBa2Cu3O7-d." Report #UBC-98-03. Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, BC, CANADA V6T 1Z1; e-mail hosseini@physics.ubc.ca; preprint also available at cond- mat@xxx.lanl.gov (#9803272). 74.25.-q; 74.25.Fy; 74.25.Nf.

W. L. Hults, J. C. Cooley, E. J. Peterson, J. L. Smith, Howard A. Blackstead, and John D. Dow, "PrBa2Cu3Ox Polycrystalline Superconductor Preparation." Contact Howard A. Blackstead, Department of Physics, University of Notre Dame, Notre Dame, IN 46556; telephone (219) 631- 7078; telefax (219) 631-5952; e-mail blackstd@rems1.phys.nd.edu.

M. N. Iliev, "Raman Spectroscopy of Phase Separation and Reordering Processes in YBCO Type Compounds." Preprint #98:031; submitted to the Proc. of the Applications of Spectroscopy to Supercond. Mater. Symp., 215th Spring Nat. Amer. Chem. Soc. Mtg., Dallas, Texas, March 29-April 3, 1998. Texas Center for Superconductivity, University of Houston, Houston, TX 77204-5932; telephone (713) 743-8200; telefax (713) 743- 8201; e-mail preprints@www.tcs.uh.edu.

Kazusumi Ino, "Pairing Effects in the Edge of Paired Quantum Hall States." Institute for Solid State Physics, University of Tokyo, Roppongi 7-22-1, Minato-ku, Tokyo 106, JAPAN; telephone +81 3 3478 6811, ext. 5823; e-mail ino@kodama.issp.u-tokyo.ac.jp; Web site http://www.issp.u-tokyo.ac.jp/labs/theory/kohmoto/ino/; preprint also available at cond-mat@xxx.lanl.gov (#9803337). 73.40.Hm; 74.20.-z.

S. T. Johnson, P. D. Hatton, A.J.S. Chowdhury, J. Gardner, G. Balakrishnan, D. McK. Paul, and J. Hodby, "Effect of Annealing Upon the High-Tc Superconductor Bi2Sr2CaCu2O8+d." To be published in Physica C (in press). Laboratoire de Physique des Solides, Universite Paris-Sud, Batiment 510, F-91405 Orsay Cedex, FRANCE; telephone +33 1 69 155306; telefax +33 1 69 155654; e-mail stuart@lps.u-psud.fr. Key words: x-ray diffraction, structure of Bi2Sr2CaCu2Od, modulated structures, oxygen vacancies, structural phase transformation.

Ch. Jooss, R. Warthmann, A. Forkl, and H. Kronmueller, "High-Resolution Magneto-Optical Imaging of Critical Currents in YBa2Cu3O7-d Thin Films." To be published in Physica C (in press). Max-Planck-Institut fuer Metallforschung, Heisenbergstr. 1, D-70569 Stuttgart, GERMANY. Key words: YBa2Cu3O7-d thin films, Biot-Savart law, magneto-optical imaging. 74.60.Jg; 78.20.Ls.

Gunter Kaiser, "Investigations on Refrigerator Cooling of HTS Sensors for Magnetometry and Bolometry." Submitted as a Ph.D. thesis (Friedrich-Schiller-Universitaet Jena). Institut fuer Luft- und Kaeltetechnik, FB Kryotechnik, Bertolt-Brecht-Allee 20, D-01309 Dresden, GERMANY; e-mail ouk@rz.uni-jena.de. Key words: HTS, SQUID, magnetometer, bolometer, cryocooler, disturbance reduction. (Thesis in German.)

K. Kakimoto, Y. Imagawa, and Y. Shiohara, "Control of Crystal Growth Rate on Unidirectional Solidification of YBCO Fibers." 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.

S. Kamal, Ruixing Liang, A. Hosseini, D. A. Bonn, and W. N. Hardy, "Magnetic Penetration Depth and Surface Resistance in YBa2Cu3O7-d: New Results for Ultra High Purity Crystals." Report #UBC-98-324. Department of Physics, University of British Columbia, Vancouver, BC, CANADA V6T 1Z1; e-mail kamal@physics.ubc.ca; preprint also available at cond-mat@xxx.lanl.gov (#9803292). 74.25.Nf; 74.62.Bf; 74.72.Bk; 74.40.+k.

Shiro Kambe, Kenichiro Abe, Kiyoshi Koike, Yuichiro Takasugi, Osamu Ishii, Toshio Furusawa, Tsuyoshi Shiomi, and Shigetoshi Ohshima, "Correlation Between Cu Valence, Hole Density and Tc of Bi2201, Bi2212 and Bi2223 Superconductors." To be published in Appl. Supercond. (in press). Graduate School of Engineering, Yamagata University, 4-3-16 Jonan, Yonezawa 992, JAPAN.

Haruichi Kanaya, Tomohiko Kaneyuki, Hidehiro Senoh, Yasuo Cho, and Ikuo Awai, "Microwave Measurement of Coplanar-Type Resonator Fabricated with YBCO Film." To be published in Appl. Supercond. (in press). Department of Electrical and Electronic Engineering, Faculty of Engineering, Yamaguchi University, 2557 Tokiwadai, Ube, Yamaguchi 755, JAPAN.

W. N. Kang, B. W. Kang, Q. Y. Chen, J. Z. Wu, S. H. Yun, A. A. Gapud, J. Z. Qu, W. K. Chu, D. K. Christen, R. Kerchner, and C. W. Chu, "Scaling of the Hall Resistivity in Epitaxial HgBa2CaCu2O6+d Thin Films with Columnar Defects." Preprint #98:030; 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. 74.60.Ge; 72.15.Jf; 74.72.Gr.

Masatsune Kato, Kenji Sakakibara, and Yoji Koike, "Rapid Synthesis of Y- and Bi-Based High-Tc Cuprates by Microwave Irradiation." To be published in Appl. Supercond. (in press). Department of Applied Physics, Graduate School of Engineering, Tohoku University, Aramaki Aoba, Aoba-ku, Sendai 980-77, JAPAN. Key words: synthesis, domestic microwave oven, YBa2Cu3O7-x, (Bi,Pb)2Sr2Can-1CunOx, electrical resistivity.

T. Kawamoto, T. Mori, Y. Misaki, K. Tanaka, H. Mori, and S. Tanaka, "Metal-Insulator Transition in the One-Dimensional Organic Conductor (TSM-TTP)(I3)5/3." To be published in Physica C (in press). Department of Organic and Polymeric Materials, Tokyo Institute of Technology, O- okayama, Tokyo 152, JAPAN. Key words: metal-insulator transition, high pressure effect, ESR, magnetic susceptibility.

Jan Kierfeld, "Topological Order in the Phase Diagram for High- Temperature Superconductors with Point Defects." To be published in Physica C (in press). Institut fuer Theoretische Physik der Universitaet zu Koeln, D-50937 Koeln, GERMANY; preprint also available from Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439; telefax (708) 252-9595; e-mail janice_coble@qmgate.anl.gov.

S. Kleefisch, L. Alff, U. Schoop, A. Marx, R. Gross, M. Naito, and H. Sato, "Superconducting Nd1.85Ce0.15CuO4-y Bicrystal Grain Boundary Josephson Junctions." To be published in Appl. Phys. Lett. II. Physikalisches Institut, Universitaet zu Koeln, Zuelpicherstr. 77, D- 50937 Koeln, GERMANY; L. Alff's e-mail alff@ph2.uni-koeln.de; preprint also available at cond-mat@xxx.lanl.gov (#9804161). 74.25.Fy; 74.50.+r.

N. Knauf, J. Fischer, P. Schmidt, B. Roden, R. Borowski, B. Buechner, H. Micklitz, A. Freimuth, D. Khomskii, and V. Kataev, "Grain Size Dependence of the Wohlleben Effect in Bi-2212 High Temperature Superconductors." To be published in Physica C (in press). Contact B. Buechner, II. Physikalisches Institut, Universitaet zu Koeln, Zuelpicher Str. 77, D-50937 Koeln, GERMANY; telephone +49 221 470 3597; telefax +49 221 470 5178; e-mail bb@colorix.ph2.uni-koeln.de. Key words: Bi-based cuprates, magnetic susceptibility, microwave absorption, d-wave superconductor. 74.25.Ha; 74.72.Hs; 74.80.Bj.

Ioan Kosztin, Simon Kos, Michael Stone, and Anthony J. Leggett, "Free Energy of an Inhomogeneous Superconductor: A Wave Function Approach." Submitted to Phys. Rev. B. Department of Physics, University of Illinois at Urbana-Champaign, 1110 West Green Street, Urbana, IL 61801; e-mail ioan@cromwell.physics.uiuc.edu; preprint also available at cond- mat@xxx.lanl.gov (#9803317). 74.20.-z; 74.20.Fg; 74.80.-g.

Barbara Lederle, "Theoretical and Experimental Determinations of the Phonon Raman Scattering Efficiency of High-Tc Superconductors." Submitted as a Ph.D. thesis (Universitaet Stuttgart). Contact Manuel Cardona, Max-Planck-Institut fuer Festkoerperforschung, Heisenbergstrasse 1, D-70569 Stuttgart, GERMANY; e-mail cardona@cardix.mpi-stuttgart.mpg.de or birtel@cardix.mpi- stuttgart.mpg.de. (Thesis in German.)

S. Li, J. C. Zhao, W. Gao, H. K. Liu, Q. Y. Hu, and S. X. Dou, "The Effects of Mechanical Deformation on the Lattice Distortion and Grain Thickness of (Bi,Pb)2Sr2Ca2Cu3O10+x Oxide Crystals." To be published in Physica C (in press). Contact W. Gao, Department of Chemical and Materials Engineering, University of Auckland, Auckland, NEW ZEALAND; telephone +64 9 373 7599; telefax +64 9 373 7463; e-mail w.gao@auckland.ac.nz.

Vadim M. Loktev, Rachel M. Quick, and Sergei G. Sharapov, "Superconducting Condensate Formation in Quasi-2D Systems with Arbitrary Carrier Density." Bogolyubov Institute for Theoretical Physics, 252143 Kiev, UKRAINE, Sergei G. Sharapov's e-mail in South Africa sharapov@scientia.up.ac.za; preprint also available at cond- mat@xxx.lanl.gov (#9804026). 74.72.-h; 74.20.Fg; 74.20.Mn; 64.60.Cn.

B. Lundqvist, A. Rydh, Yu. Eltsev, OE. Rapp, and M. Andersson, "Empirical Scaling of the Vortex Glass Line Above 1 T for High-Tc Superconductors of Varying Anisotropy." To be published in Phys. Rev. B. Department of Solid State Physics, Royal Institute of Technology, SE-100 44 Stockholm, SWEDEN. 74.60.Ge; 74.25.Fy; 74.72.Bk.

H. Maeda, K. Kakimoto, M. Kikuchi, J. O. Willis, K. Watanabe, Y. Tanaka, and H. Kumakura, "Microstructures and Superconducting Properties of V Doped Bi2223 Tapes." To be published in Appl. Supercond. (in press). Institute for Materials Research, Tohoku University, Katahira 2-1-1, Aoba-ku, Sendai 980, JAPAN; telephone +81 22 227-6200; telefax +81 22 264-7984.

P. Massiot, C. Perrin, M. Guilloux-Viry, and M. Gauneau, "Influence of Halogenation on Superconducting Properties of Oxygen-Deficient YBa2Cu3Ox Thin Films: Comparison with Halogenation of YBa2Cu3Ox Ceramics." To be published in Physica C (in press). Contact C. Perrin, Laboratoire de Chimie du Solide et Inorganique Moleculaire, UMR CNRS 6511, Universite de Rennes I, Avenue du General Leclerc, F-35042 Rennes Cedex, FRANCE; telephone +33 2 99 286123; telefax +33 2 99 635704. Key words: halogenation, thin film, superconducting, YBa2Cu3Ox, HTSC. 68.55.Ln.

N. Matsubara, N. Yoshizawa, M. Konno, N. Iwata, and S. Tsunakawa, "Unit Cell Parameter Displacement with Temperature and Oxygen Contents in a High-Tc Phase Pb-Bi-Sr-Ca-Cu-O System Superconductor." To be published in Appl. Supercond. (in press). Department of Engineering, Material Science Section, Touin Yokohama University, 1614 Kuroganecho, Aobaku, Yokohama 225, JAPAN.

Y. Matsuo, T. Nojima, E. Majkova, and Y. Kuwasawa, "Finite-Size Effect on Vortex Loop Excitation in Amorphous-W/Si Multilayers." To be published in Physica C (in press). Contact Y. Matsuo, c/o Y. Kuwasawa, Faculty of Science, Department of Physics, Chiba University, 1-33 Yayoicho, Inage-ku, Chiba 263, JAPAN; telephone +81 43 290 2756; telefax +81 43 290 2874; e-mail matsuo@physics.s.chiba-u.ac.jp. Key words: finite size effect, vortex configuration, critical scaling. 74.40.+k.

S. Matsuoka, M. Sumida, T. Umeda, and Y. Shiohara, "Microstructure of High Jc NdBa2Cu3Ox/Nd4Ba2Cu2O10 Composite Superconductor." 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. Key words: Nd123 superconductor, Nd422 particles, floating-zone partial melting and solidification, microstructure control, Pt addition.

V. Metlushko, U. Welp, I. Aranson, S. Scheidl, V. M. Vinokur, G. W. Crabtree, K. Rogacki, and B. Dabrowski, "Driven Vortex States and Relaxation in Single Crystal YBa2Cu4O8." Submitted to Phys. Rev. Lett. Materials Science Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439; telefax (708) 252-9595; I. Aranson's e-mail aronson@vortex.msd.anl.gov; preprint also available at cond- mat@xxx.lanl.gov (#9804121). 74.60.Ge.

J. H. Miller, Jr., "Macroscopic Coulomb Blockade Model of Density Wave Transport." Preprint #98:003; submitted to Phys. Rev. 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 or jhmiller@uh.edu; preprint also available at cond-mat@xxx.lanl.gov (#9804001). 73.23.Hk; 72.15.Nj; 71.45.Lr; 75.30.Fv; 11.25.Sq.

E. P. Nakhmedov and M. Huener, "Interlayer Pairings in the Josephson- Coupled Layered Superconductors." To be published in Physica C (in press). Faculty of Sciences and Letters, Department of Physics, Istanbul Technical University, Maslak, 80626 Istanbul, TURKEY. Key words: Josephson tunneling, Lifschitz invariant, Ginzburg-Landau free energy functional, Gor'kov-Nambu theory. 74.20.Fg; 74.50.+r; 74.60.-w.

T. Niemoeller, B. Buechner, M. Cramm, C. Huhnt, L. Troeger, and M. Tischer, "X-Ray Absorption Fine Structure of Rare Earth Doped (La,Sr)2CuO4." To be published in Physica C (in press). II. Physikalisches Institut, Universitaet zu Koeln, Zuelpicher Str. 77, D- 50937 Koeln, GERMANY; B. Buechner's telephone +49 221 470 3597; telefax +49 221 470 5178; e-mail bb@colorix.ph2.uni-koeln.de. Key words: EXAFS, structural phase transition, stripe correlations. 61.10.Ht; 64.60.-i.

A. Oka, S. Koyama, H. Kutami, and Y. Shiohara, "Study of Twin Formation in NdBa2Cu3O7-d Single Crystal by Using High Temperature Polarized Optical Microscopy." 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.

Kyungwha Park and David A. Huse, "The Phase Transition to a Square Vortex Lattice in Type-II Superconductors with Fourfold Anisotropy." Department of Physics, Princeton University, Princeton, NJ 08544; e-mail kpark@puhep1.princeton.edu; preprint also available at cond- mat@xxx.lanl.gov (#9804070).

V. Petrykin, A. Karpov, V. Poltavec, S. Lee, M. Kakihana, and Yu. Tretyakov, "Studies of the La1+xBa2-xCu3Oz Prepared from Highly Homogeneous Precursors." To be published in Appl. Supercond. (in press). Tokyo Institute of Technology, Yokohama, JAPAN; telefax +81 45 924 5309; e-mail valery1@rlem.titech.ac.jp.

M. W. Pieper, F. Wiekhorst, and T. Wolf, "Carrier Doping in Pr1+xBa2- xCu3O7 Studied by NMR." Submitted to Phys. Rev. Lett. Institut fuer Angewandte Physik, Universitaet Hamburg, Jungiusstrasse 11, D-20355 Hamburg, GERMANY; e-mail pieper@physnet.uni-hamburg.de; preprint also available at cond-mat@xxx.lanl.gov (#9803336). 61.50.Nw; 74.72.Jt; 76.60.Jx.

E. Polturak, G. Koren, D. Cohen, O. Nesher, R. G. Mints, and I. Snapiro, "Role of Interfaces in the Proximity Effect in Anisotropic Superconductors." Submitted to Phys. Rev. B. Department of Physics, Technion - Israel Institute of Technology, Haifa 32000, ISRAEL; telephone +972 4 8292761; telefax +972 4 8221514; e-mail emilp@physics.technion.ac.il; preprint also available at cond- mat@xxx.lanl.gov (#9803361). 74.80.Fp; 74.50.+r; 74.20.Mn.

T. V. Ramakrishnan, "Magnetic Field Induced id_[xy] Order in a d_[x^2- y^2] Superconductor." Presented at the Conf. on Spectroscopies in Novel Supercond. (SNS '97), Cape Cod, Mass., Sept. 14-18, 1997. Department of Physics, Indian Institute of Science, Bangalore 560 012, INDIA; preprint also available at cond-mat@xxx.lanl.gov (#9803069).

H. D. Ramsbottom, H. Ito, T. Horita, and K. Osamura, "Current-Voltage Characteristics and Transport Current Distributions in Ag/Bi-2223 Monocore Tapes." To be published in Appl. Supercond. (in press). Department of Materials Science and Engineering, Kyoto University, Sakyo-ku, Kyoto 606-01, JAPAN.

T. V. Chandrasekhar Rao, V. C. Sahni, P. K. Mishra, G. Ravikumar, C. V. Tomy, G. Balakrishnan, D. McK. Paul, C. A. Scott, S. S. Banerjee, N. G. Patil, Subir Saha, S. Ramakrishnan, A. K. Grover, and S. Bhattacharya, "Muon Spin Rotation Evidence for Loss of Order in the Flux Line Lattice in the Peak Effect Region in 2H-NbSe2." To be published in Physica C (in press). Contact T. V. Chandrasekhar Rao or V. C. Sahni, Technical Physics and Prototype Engineering Division, Bhabha Atomic Research Centre, Mumbai 400 085, INDIA. Key words: Muon spin rotation, flux line lattice, 2H-NbSe2.

A. Sacuto, R. Combescot, N. Bontemps, C. A. Mueller, V. Viallet, and D. Colson, "Electronic Raman Scattering in HgBa2Ca2Cu3O8+d Single Crystals: Analysis of the Superconducting State." Laboratoire de Physique de la Matiere Condensee, Ecole Normale Superieure, 24 rue Lhomond, F-75005 Paris, FRANCE; R. Combescot's e-mail roland.combescot@lps.ens.fr; preprint also available at cond-mat@xxx.lanl.gov (#9804060). 74.25.-q; 74.72.Gr; 78.30.-j; 74.20.-z.

Masahiro Sakai, Akihiro Odagawa, Hideaki Adachi, and Kentaro Setsune, "Collective Switching and Heat Diffusion of Stacked Intrinsic Josephson Junctions." To be published in Physica C (in press). Central Research Laboratories, Matsushita Electric Ind. Co., Ltd., 3-4 Hikaridai, Seika, Soraku, Kyoto 619-02, JAPAN; telephone +81 774 98 2514; telefax +81 774 98 2585; e-mail sakai@crl.mei.co.jp. Key words: intrinsic Josephson junction, (Bi,Pb)2Sr2Ca2Cu3O10+x, thin film, heat diffusion, collective switching. 74.50.+r; 74.72.Hs; 74.76.Bz.

Sujit Sarkar, "Superconductivity in the Nonadiabatic Limit." To be published in Physica C (in press). Department of Physics, Indian Institute of Science, Bangalore 560 012, INDIA. Key words: nonadiabatic superconductivity, Migdal-Eliashberg formalism, isotope- shift exponent, pressure coefficient of superconducting transition temperature. 74.20.Mn; 74.62.Fj.

T. Sasagawa, K. Kishio, Y. Togawa, J. Shimoyama, and K. Kitazawa, "First-Order Vortex-Lattice Phase Transition in (La1-xSrx)2CuO4 Single Crystals: Universal Scaling of the Transition Lines in High-Temperature Superconductors." To be published in Phys. Rev. Lett. Department of Superconductivity, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, JAPAN. 74.60.Ge; 74.72.Dn.

K. Schlenga, R. Kleiner, G. Hechtfischer, M. Moessle, S. Schmitt, Paul Mueller, Ch. Helm, Ch. Preis, F. Forsthofer, J. Keller, H. L. Johnson, M. Veith, and E. Steinbeiss, "Tunneling Spectroscopy with Intrinsic Josephson Junctions in Bi2Sr2CaCu2O8+d and Tl2Ba2Ca2Cu3O10+d." To be published in Phys. Rev. B (in press). Department of Physics, University of California at Berkeley, 366 LeConte #7300, Berkeley, CA 94720; telephone (510) 642-3634; telefax (510) 642-1304; e-mail schlenga@physics.berkeley.edu. 74.80.Dm; 74.50.+r; 74.25.Kc; 74.25.Jb.

Nils Schopohl, "Transformation of the Eilenberger Equations of Superconductivity to a Scalar Riccati Equation." Institut fuer Theoretische Physik, Eberhard-Karls Universitaet Tuebingen, Auf der Morgenstelle 14, D-72076 Tuebingen, GERMANY; e-mail nils.schopohl@uni- tuebingen.de; preprint also available at cond-mat@xxx.lanl.gov (#9804064).

J. A. Selvaggi, D. L. Cottrell, T. H. Falconer, M. A. Daugherty, D. E. Daney, D. D. Hill, and F. C. Prenger, "High Gradient Magnetic Separation Using a High Temperature Superconducting Magnet." To be published in Appl. Supercond. (in press). 100 Denniston Street, The Gables #304, Pittsburgh, PA 15206.

S. Sergeenkov, "On Piezophase Effects in Mechanically Loaded Atomic Scale Josephson Junctions." To be published in J. Phys. Cond. Mat. Bogoliubov Laboratory of Theoretical Physics, Joint Institute for Nuclear Research, 141980 Dubna, Moscow Region, RUSSIA; e-mail ssa@thsun1.jinr.dubna.su.

J. B. Shi, Y. Hsu, and C. T. Lin, "Dielectric Properties of Gd2CuO4." To be published in Physica C (in press). Department of Electronic Engineering, Feng Chia University, Taichung 407, Taiwan, REPUBLIC OF CHINA. Key words: Gd2CuO4, dielectric properties, polarizability.

S. Y. Shim, D. H. Kim, H. R. Lim, J. S. Hwang, J. H. Park, C. H. Kim, S. S. Choi, and T. S. Hahn, "Photoresponse of Resistive and Kinetic Inductive YBa2Cu3Ox Bolometer." To be published in Appl. Supercond. (in press). Department of Physics, Yeungnam University, Kyungsan 712-749, KOREA.

Hajime Shimizu, Kunihiko Fujiwara, and Kenji Hatada, "Properties of the CuO2 Plane in YBa2Cu3Oy (6 < y < 7) Probed by Er EPR." To be published in Physica C (in press). Department of Electronics and Computer Science, Science University of Tokyo in Yamaguchi, Onoda, Yamaguchi 756, JAPAN. Key words: high-Tc superconductor, YBCO, EPR.

Y. Shiohara, "Single Crystal Growth and Solidification Processing of Nd123 Superconductive Oxides." 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.

Thomas Strach, "Raman Investigations of Crystal Field Excitations and Their Interaction with Phonons in High Tc and Related Materials." Submitted as a Ph.D. thesis (Universitaet Stuttgart). Contact Manuel Cardona, Max-Planck-Institut fuer Festkoerperforschung, Heisenbergstrasse 1, D-70569 Stuttgart, GERMANY; e-mail cardona@cardix.mpi-stuttgart.mpg.de or birtel@cardix.mpi- stuttgart.mpg.de. (Thesis in German.)

G. Subramanyam, F. Van Keuls, and F. A. Miranda, "A Novel K-Band Tunable Microstrip Bandpass Filter Using a Thin Film HTS/Ferroelectric/Dielectric Multilayer Configuration." To be published in IEEE MTT-S Int. Microwave Symp. Digest (1998). Contact F. Van Keuls, NASA Lewis Research Center MS 54-5, 21000 Brookpark Road, Cleveland, OH 44135; telefax (216) 433-8705; e-mail vankeuls@lerc.nasa.gov.

Y. S. Sudershan, Amit Rastogi, S. V. Bhat, A. K. Grover, Y. Yamaguchi, K. Oka, and Y. Nishihara, "Possible Non-Resonant rf Absorption Evidence for Superconducting Fluctuations Above Tc in Bi2Sr2CaCu2O8 Single Crystals." To be published in Solid State Commun. Contact S. V. Bhat, Department of Physics, Indian Institute of Science, Bangalore 560 012, INDIA; e-mail svbhat@physics.iisc.ernet.in. Key words: high-Tc superconductors, electron-electron interactions.

Y. S. Sudershan, Amit Rastogi, S. V. Bhat, A. K. Grover, Y. Yamaguchi, K. Oka, Y. Nishihara, L. Senapati, and D. Kanjilal, "Suppressed rf Dissipation in [107]^Ag^[17+] Ion Irradiated Bi2Sr2CaCu2O8 Single Crystals by Enhanced Flux Line Tilt Modulus." To be published in Appl. Phys. Lett. Contact S. V. Bhat, Department of Physics, Indian Institute of Science, Bangalore 560 012, INDIA; e-mail svbhat@physics.iisc.ernet.in.

B. Suresh, "A New Mechanism of Superconductivity." Submitted to Phys. Rev. Lett. BHEL MIG 1141, R.C. Puram, Hyderabad 500032, A.P. INDIA; telephone +91 40 3022816; telefax +91 40 3034363; e-mail meghent@hd1.vsnl.net.in.

J. P. Sydow, D. Chamberlain, F. Ronnig, Y. Xu, and R. A. Buhrman, "Optimal Oxygenation of YSr2Cu2.75Mo0.25Oz Thin Films." To be published in Physica C (in press). School of Applied and Engineering Physics, Cornell University, Ithaca, NY 14853-2501. Key words: synthesis of YSr2Cu2.75Mo0.25Oz, Raman scattering, electromigration, oxygen stoichiometry.

T. Tadic, Y. Mokuno, K. Fujii, Y. Horino, N. Brnicevic, I. Basic, P. Planinic, and M. Jaksic, "Application of Chemical Effects in X-Ray Spectra for Characterization of the High-Tc Superconductors." To be published in Appl. Supercond. (in press). Osaka National Research Institute, 1-8-31 Midorigaoka, Ikeda, Osaka 563, JAPAN; telefax +81 727 51 9631; e-mail ttadic@onri.go.jp.

F. Tafuri, B. Nadgorny, S. Shokhor, M. Gurevitch, F. Lombardi, F. Carillo, A. Di Chiara, and E. Sarnelli, "A Study of Barrier Properties in Y1Ba2Cu3O7-x Grain Boundary Josephson Junctions Using Electron Beam Irradiation." To be published in Phys. Rev. B. INFM-Dipartimento di Scienze Fisiche, Universita di Napoli "Federico II", Piazzale Tecchio 80, I-80125 Napoli, ITALY. 74.50.+r; 74.72.Bk; 74.76.Bz; 85.25.Cp.

Yasutami Takada and Takashi Hotta, "Superconductivity in the Alkali- Doped Fullerides: Competition of Phonon-Mediated Attractions with Coulomb Repulsions in Polaron Pairing." ISSN 0082-4798, preprint #3367; submitted to Int. J. Mod. Phys. B. Institute for Solid State Physics, University of Tokyo, 7-22-1 Roppongi, Minato-ku, Tokyo 106-8666, JAPAN.

Hideki Tanaka, Kazuhiro Kuboki, and Manfred Sigrist, "Study on Nonmagnetic Impurities in the Superconducting State of Two-Dimensional t-J Model." Department of Physics, Kobe University, 1-1 Rokkodai, Nada- ku, Kobe 657, JAPAN; Kazuhiro Kuboki's telephone +81 78 803 0522; telefax +81 78 803 0522; e-mail kuboki@phys.kobe-u.ac.jp; preprint also available at cond-mat@xxx.lanl.gov (#9804076). Key words: high-Tc superconductivity, t-J model, d-wave symmetry, nonmagnetic impurity.

K. Waki, T. Higuchi, S. I. Yoo, and M. Murakami, "A Comparison of the Irreversibility Line Between Melt-Processed Nd-Ba-Cu-O and Y-Ba-Cu-O Superconductors." 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.

Q. Wang, J. Katsuta, T. Kikuchi, S. Kohjiro, and A. Shoji, "Overdamped NbCxN1-x Josephson Junctions with Sputter-Deposited TiNx Layers or MgO/TiNx Bilayers as Barriers." To be published in Appl. Supercond. (in press). Contact A. Shoji, Electrotechnical Laboratory, 1-1-4 Umezono, Tsukuba, Ibaraki 305, JAPAN.

Zhong Yue Wang, "On the Mechanism of Superconductivity." To be published in Physica C (in press). Box 504, No. 144, Tonghe-6 Residence Zone, Gongjiang Road, Shanghai 200435, PEOPLE'S REPUBLIC OF CHINA. Key words: quantum mechanics, BCS theory, Cooper pairs. 03.65.-w; 74.20.- z.

X.-J. Wu, T. Tamura, S. Adachi, T. Tatsuki, and K. Tanabe, "Crystal Structure of 'Pb'-1234 Superconductor." To be published in Physica C (in press). Superconductivity Research Laboratory, International Superconductivity Technology Center (ISTEC), 10-13 Shinonome 1-chome, Koto-ku, Tokyo 135, JAPAN; telephone +81 3 3536-5703 through -5705; telefax +81 3 3536-5714 or -5717. Key words: 'Pb'-1234 phase, x-ray Rietveld refinement, crystal structure, superstructure.

X. Yao, E. Goodilin, H. Sato, and Y. Shiohara, "Mixing Y(RE)BCO (RE=Nd,Sm) Superconductors by Crystal Pulling Method." 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. Key words: substitution effects, superconductivity, crystal pulling method.

Daole Yin, Chuanyi Li, and Weiping Bai, "The Materials Equation and Scaling Law of Flux Pinning in High-Tc Superconductors." To be published in Appl. Supercond. (in press). Department of Physics, Beijing University, Beijing 100871, PEOPLE'S REPUBLIC OF CHINA.

N. D. Zhigadlo, V. V. Petrashko, Yu. A. Semenenko, C. Panagopoulos, J. R. Cooper, and E.K.H. Salje, "The Effects of Cs Doping, Heat Treatments on the Phase Formation and Superconducting Properties of (Bi,Pb)-Sr-Ca- Cu-O Ceramics." To be published in Physica C (in press). Institute of Solid State and Semiconductor Physics, Byelorussian Academy of Sciences, P. Brovki 17, Minsk 220072, BELARUS. Key words: high-Tc superconductors, (Bi,Pb)-Sr-Ca-Cu-O, Cs doping, heat treatments.

Igor Zutic and Oriol T. Valls, "Low Frequency Nonlinear Magnetic Response of an Unconventional Superconductor." Submitted to Phys. Rev. B. School of Physics and Astronomy and Minnesota Supercomputer Institute, University of Minnesota, Minneapolis, MN 55455-0149; e-mail izutic@physics.spa.umn.edu. 74.25.Nf; 74.20.De.

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

*May 26 - 28, 1998: 10th International Cryocooler Conference, Monterey Conference Center, Monterey, Calif. Invited technical topics include Stirling and pulse-tube cryocoolers, J-T and sorption cryocoolers, G-M and TEC cryocoolers, new concepts, component developments, modeling and test techniques, performance and life test data, applications and integration issues, and low-cost coolers. Oral and poster sessions. For information, contact Peter Kittel, ICC10, MS-244-10, NASA/Ames Research Center, Moffett Field, CA 94035-1000; telephone (650) 604-4297; telefax (650) 604-1094; e-mail pkittel@mail.arc. nasa.gov; Web site http://www.cryosource.com/ic10.html.

July 14 - 17, 1998: Seventeenth International Cryogenic Engineering (ICEC 17), Bournemouth International Centre, Bournemouth, United Kingdom. Purpose is to bring together people from universities, research institutions, and industry to stimulate the fruitful exchange of information and ideas in cryogenic engineering, to outline actual trends, and to discuss present and future developments. Subjects for ICEC 17 are expected to include: large- and small-scale refrigeration, liquefaction, and gas-separation technology; space applications of cryogenic engineering; materials and fluid properties and their influence on the design of low-temperature equipment; high-temperature ceramic superconductors and low-temperature metallic superconductors -- their manufacture and applications; active/passive superconducting devices -- their manufacture and applications; cryoelectronics including superconducting and nonsuperconducting circuitry; cryogenic wind tunnels; applications of cryogenics to medicine, biology, and food preservation; liquid helium, hydrogen, and neon technology; centenary of hydrogen liquefaction; and significant contributions dealing with other aspects of cryogenic engineering. For information, contact ICEC 17 Conference Office, Kryos Associates, 22 Brookvale Road, Southampton SO17 1QP, United Kingdom; telephone +44 1 703 579762; telefax +44 1 703 579762; e-mail ICEC17@soton.ac.uk; Web site http://www.soton.ac.uk/~crenergy/ICEC17/index.html.

July 19 - 24, 1998: SPIE's 43rd Annual Meeting: International Symposium on Optical Science, Engineering, and Instrumentation, San Diego Convention Center and Marriott Hotel and Marina, San Diego, Calif. Will include sessions on superconducting superlattices (native and artificial) and the physics and nanoengineering of superconducting and related oxides. For information, contact SPIE, P.O. Box 10, Bellingham, WA 98227-0010; telephone (360) 676-3290; telefax (360) 647-1445; e-mail sd98@spie.org; Web site http://www.spie.org/info/sd/.

*July 19 - 24, 1998: Gordon Research Conference on Correlated Electron Systems, Plymouth State College, Plymouth, N.H. 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 . A substantial block of time will be set aside for discussions to be coordinated by the session chair. Will include formal invited sessions and contributed poster sessions; discussion on posters will 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.

*July 20 - 31, 1998: Tenth Trieste Workshop on Open Problems in Strongly Correlated Electron Systems, Miramare, Trieste, Italy. Workshop will include both experimentalists and theorists, and will foster the interaction between these two components of the field. Topics include: disorder and strong correlations, realizations of correlated electron physics in mesoscopic devices, non-Fermi-liquid physics, experimentally motivated aspects of cuprate physics, old and new puzzles in heavy fermion physics, and other new phenomena in transition metal oxides. Workshop is open to research workers from all countries that are members of the United Nations, UNESCO, or IAEA. No registration fee. 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; e-mail smr1068@ictp.trieste.it; Web site http://www.ictp.trieste.it/.

*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 will include 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. Selected papers will be published in IEEE Transactions on Appl. Supercond. For general information 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 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.

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, #9, May 1, 1998.