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RBa2Cu3O7-d

Papers by M. Muralidhar (SRL-ISTEC) et al. and by M. Muralidhar and M. Murakami (SRL-ISTEC) report on the superconducting properties of oxygen- controlled-melt-growth (OCMG) (Nd,Eu,Gd)Ba2Cu3Oy (NEG-123) samples containing additions of (Nd,Eu,Gd)2BaCuO5 (NEG-211), Pt, and CeO2. For an NEG sample with 40 mol% NEG-211 additions, resulting in very fine (~0.1 micrometer) mostly Gd-211 particles, the authors observed a critical current density Jc of 6 x 10^4 A/cm^2 at 77 K in a magnetic field of 3 T applied parallel to the c-axis. Similar zero-field and peak Jc values were obtained in samples containing 30 and 40 mol% of NEG-211. While Pt appears to assist in refining the size of the NEG-211 particles and enhancing Jc, CeO2 was found to be less effective.

Using transmission electron microscopy, F. Sandiumenge (Barcelona) et al. have found a three-dimensional dislocation substructure in an as- grown directionally solidified sample of NdBa2Cu3O7-d. Dislocations with a near or perfect [001] orientation and with Burgers vectors lying on the basal plane were found to glide on (010) and {110}. This results in the natural occurrence of dislocation lines perpendicular to the basal planes acting as linear pinning centers normal to the weakly coupled CuO2 layers. The authors propose a model in which cubic-like glide is achieved through the formation of a track of Nd-->Ba antisites along the path swept by the dislocations. This finding can be correlated with enhanced flux pinning under H||[001] observed in these materials.

Using thermal neutrons to irradiate two ceramic samples of GdBa2Cu3O7-d, one with [155]^Gd (sigma = 61,000 b) and the other with [160]^Gd (sigma = 0.77 b), G. Brandstaetter et al. (Atominstitut-Wien) have learned that the overall contribution of point defects to flux pinning in 123 superconductors is small.

The effects of the heating rate (100^oC/h - 6,000^oC/h) to a peritectic temperature (T_p = 1,015^oC) on conversion of Y2O3-BaCuO2-CuO and Y2BaCuO5-BaCuO2-CuO precursor powders into YBa2Cu3O7-d (Y-123) have been studied by C.-J. Kim et al. (KAERI). The authors found that both precursor powders were rapidly converted into the Y-123 phase.

Two preprints by D. K. Aswal et al. (Shizuoka) report in-situ measurements of the growth rate of YBa2Cu3O7-d single crystals along the [100]/[010] directions using high-temperature optical microscopy. The authors found that the growth rate of the YBa2Cu3O7-d crystals is intimately related to the dissolution of Y2BaCuO5 particles in the liquid.

Using ultrafast time-resolved optical spectroscopy, V. V. Kabanov et al. (Ljubljana) have experimentally and theoretically investigated photoexcited quasiparticle relaxation dynamics in superconducting YBa2Cu3O7-d as a function of doping d and temperature T. The observed photoinduced transmission |DeltaT/T|, reflection |DeltaR/R|, and quasiparticle relaxation time tau were found to agree quantitatively over a wide range of doping (0.1 < d < 0.48) with a temperature- dependent BCS-like isotropic gap near optimum doping (d < 0.1) and a temperature-independent isotropic gap in underdoped YBa2Cu3O7-d (0.15 < d < 0.48). A pure d-wave gap was found to be inconsistent with the data.

Bi Cuprates

A preprint by G. Villard et al. (Caen) reports magnetization measurements of the penetration depth lambda_[ab](0) and second peak H_[sp] in Bi2Sr2CaCu2O8+d (Bi-2212) single crystals with doping levels ranging from the underdoped to the overdoped regime. The authors observed a boomerang shape for the Tc vs. 1/lambda_[ab]^2(0) curve in the region 0.8 <= Tc/Tc^[max] <= 1. On the overdoped side of the boomerang, 1/lambda_[ab]^2(0) decreases as the doping level increases, while the second-peak field H_[sp] increases monotonically.

A near-net-shape process for Ag-clad Bi-2212 superconductors has been developed by M. T. Lanagan (Argonne) et al. The authors note that this alternative to the powder-in-tube process offers the advantages of nearly continuous processing, minimization of processing steps, reasonable ability to control the Bi-2212/Ag ratio, and early development of favorable texture of the Bi-2212 grains.

The primary phase field (the compositional region one can use for crystal growth and melt processing) of the 110 K high-Tc superconductor (Bi,Pb)2Sr2Ca2Cu3O10+d [Bi(Pb)-2223] under the condition of 7.5% O2 has been determined by W. Wong-Ng (NIST-Gaithersburg) et al. The presence of liquid has been known to be critical during the processing of Bi(Pb)- 2223. The authors provide information concerning the set of 29 five- phase equilibrium volumes that contain the 2223 phase, and they give the initial liquid composition of these volumes.

A significant reduction of ac losses in twisted Bi-2223 multifilamentary tapes with Ag sheaths has been achieved by Y. B. Huang (Geneve) et al. using oxide (BaZrO3 and SrZrO3) barriers between filaments. These barriers have two important effects: they increase the transverse resistivity, which suppresses induced coupling currents, and they reduce filament bridging, which in pure Ag-sheathed tapes largely cancels the beneficial effect of filament twisting. The decoupling can be gauged by the frequency f_m at which the losses show a maximum in a low-amplitude field applied perpendicular to the tape. To date, f_m has been enhanced from 5 Hz (untwisted) to 82 Hz (11 mm in twist pitch length). The authors discuss different ways to introduce oxide barriers in tapes with 19 to 95 filaments.

Comparisons of three methods of measuring the ac losses in 1-1.5 m segments of a Bi-2223 cable conductor fabricated by Pirelli in a longer length are reported by G. Coletta (Pirelli) et al. The authors discuss the main features of two calorimetric methods, one based on temperature- profile determinations, the other based on the liquid-nitrogen boil-off rate, and an electrical method, based on voltage measurements using a lock-in amplifier. The authors analyze and discuss the advantages and limits of each approach.

Measurements of the ac losses in individual Bi-2223 tapes and in a 1 kA transmission line model are reported by L. M. Fisher (Moscow) et al. A 5 m long model transmission line was fabricated from 120 tapes for the forward line and 120 tapes for the return line. The ac losses in the current core were found to be substantially greater than those seen in the individual tapes.

Measurements of the critical current and magnetic field performance of long-length Bi-2223/Ag composite superconducting tapes fabricated by a consortium involving Metal Manufactures, Ltd. (MM Cables), the University of Wollongong, and CSIRO are reported in a paper by N. Savvides (CSIRO) et al. The authors also report self-field transport ac losses and strain performance.

The room-temperature elastic constants of a dense, bulk (Bi,Pb)2Sr2Ca2Cu3O10+d bar, fabricated by sinter forging, have been measured by K. C. Goretta (Argonne) et al. The bar exhibited excellent phase purity and strong texturing, with the c-axes aligned parallel to the forging direction. One elastic constant also was measured to 760^oC. The authors report that Bi-2223 is 25-30% stiffer than Bi2Sr2CaCu2O8+d.

A nondestructive, noncontact, continuous quality test for the uniformity of Bi-2223 tape is proposed in a preprint by R. Weinstein (TCSUH) et al. The method, based on Hall-probe measurements of the trapped field of a field-cooled tape, should be capable of revealing ~4% variations of critical current along the length of the tape.

Other Cuprates

Measurements of the low-temperature specific heat (LTSH) of La2-xSrxCuO4 (x = 0.10, 0.16, and 0.22) as a function of applied magnetic field have been carried out by S. J. Chen (National Sun Yat-Sen University) et al. Such measurements probe the influence of lines of nodes in the superconducting order parameter. The authors found that in all doping regimes, the increase in the linear-T coefficient gamma is proportional to H^[1/2], consistent with d-wave superconductivity. The data also show evidence for an [alpha]T^2 term at zero magnetic field in the LTSH of La1.78Sr0.22CuO4.

The far-infrared sphere resonance in T*-phase SmLa0.8Sr0.2CuO4-d powder samples has been measured by H. Shibata and T. Yamada (NTT) down to 7 cm^[-1]. Below Tc, the authors observed two peaks, one at 11 cm^[-1] and the other at 30 cm^[-1] for d = 0.05. Comparing with the ...S/I/S/I'/S/I/S/I'/S... (...superconductor/insulator1/superconductor/insulator2/superconductor.. .) Josephson junction array model discussed by van der Marel and Tsvetkov, the authors attribute the two peaks to the different Josephson plasma resonances of the intrinsic Josephson junctions at the fluorite- type Sm2O2 block layer and the rocksalt-type (La,Sr)2O2-d block layer. Both peaks shift to lower frequencies as the doping decreases. The authors suggest that other cuprates with two intracell couplings, such as (Eu,Ce)2(Ba,Eu)2Cu3O10-d, (Pb,Cu)(Eu,Ce)2(Sr,Eu)2Cu2O9, Bi2Sr2(Gd,Ce)2Cu2O10, and (Tl,Pb)(CO3)Sr4Cu2O7, also should show double Josephson plasma resonances.

Single crystals of optimally doped and moderately and strongly overdoped Tl2Ba2CuO6+d (Tl-2201) with Tc = 80, 56, and 30 K, respectively, have been investigated by L. V. Gasparov (Aachen and Chernogolovka) et al. using polarized Raman scattering. Taking the peak position of the Bi_[1g] component of the electronic Raman scattering as 2Delta_0, the authors found that the reduced gap value (2Delta_0/k_BTc) strongly decreases with increasing doping. The behavior of the low-frequency scattering for the B_[1g] and B_[2g] scattering is similar for optimally doped and overdoped crystals and can be described by omega^3 and omega laws, respectively, behavior consistent with d-wave symmetry of the order parameter.

Measurements by K. Fujinami (Tokyo Tech) et al. of the irreversibility field H_[irr] vs. reduced temperature T/Tc in HgBa2Ca2Cu3O8+d (Hg-1223) show that the H_[irr] vs. T/Tc characteristics improve with increasing oxygen excess d. The authors conclude that overdoped Hg-1223 is a good candidate for a superconducting material with Tc > 100 K in high magnetic field applications.

Vortices

The c-axis resistivity in irradiated and pristine Bi2Sr2CaCu2O8+d (Bi- 2212) crystals has been measured by N. Morozov (Los Alamos) et al. as a function of the in-plane magnetic field component at fixed out-of-plane component B_c in the vortex-liquid phase at T = 67 K. From this data the authors extracted the phase-difference correlation function and the correlation length of the pancake density correlation function along the c axis as a function of the filling factor f = B_c/B_[phi]. The authors found that the correlation length reaches a maximum of about 15 interlayer distances near f ~~ 0.35.

A theoretical paper by D. Ertas (Exxon Research & Engineering) reports calculations of the thermal depinning of a single vortex from a single nonuniform columnar defect.

Taking into account only the magnetic interactions between pancake vortices in highly anisotropic layered superconductors, A. Buzdin (Bordeaux) finds that vortices will be trapped by tilted columnar defects even when the external magnetic field is oriented along the c axis. For such tilted trapped vortices, the interaction at long distance becomes attractive in some directions, which should lead to the formation of vortex chains with an intervortex distance of the order of the London penetration depth.

The well-known reversal of the magnetic field pattern of a vortex line not parallel to a symmetry axis of an anisotropic superconductor, and the corresponding attraction between two parallel vortex lines are discussed in a preprint by P. Muzikar (Purdue). The author uses perturbation theory to identify the supercurrents responsible for the magnetic field pattern and to determine the relevant screening lengths involved.

Using large-scale Monte Carlo simulations on a uniformly frustrated 3D- XY model, S.-K. Chin et al. (Trondheim) have found a first-order vortex crystal melting transition in clean, isotropic, extreme type-II (kappa-- >infinite) superconductors. The authors stress that this clarifies an important issue: that the unpinned vortex liquid is always incoherent with no phase coherence in any direction for all anisotropies, and that previous findings of a disentangled vortex liquid (line liquid) based on simulations for isotropic superconductors were due to finite-size effects.

A paper by A. K. Kienappel and M. A. Moore (Manchester) reports on simulations of layered superconductors using the Lawrence-Doniach model in the framework of the lowest-Landau-level approximation. The authors find a first-order phase transition with a B(T) dependence that agrees well with what has been identified as the experimental melting line in YBa2Cu3O7-d. However, the authors assert that this transition is not associated with vortex-lattice melting but instead separates two vortex- liquid states characterized by different degrees of short-range crystalline order and different length scales of correlations between vortices in different layers. The transition line ends at a critical end-point at low fields. The authors find the magnetization discontinuity and the location of the lower critical magnetic field to be in good agreement with experiments in YBa2Cu3O7-d. They also find that the first-order phase transition persists in the presence of weak random point disorder but can be suppressed entirely by strong disorder. No vortex-glass or Bragg-glass state is found in the presence of disorder.

The depinning of a massive elastic manifold with d internal dimensions, embedded in a (d+n)-dimensional space, and subject to an isotropic pinning potential V(u) = V(|u|) has been investigated by D. A. Gorokhov and G. Blatter (ETH-Zurich). The authors also discuss the application of their results to the problem of depinning of vortices in high-Tc superconductors.

A preprint by I. Vekhter (Guelph) et al. shows that the density of states and the thermodynamic properties of a 2D d-wave superconductor in an applied in-plane magnetic field H depend on the angle between H and the order-parameter nodes. Within a semiclassical treatment of the extended quasiparticle states, the authors obtain fourfold oscillations of the specific heat, whose measurement should provide a simple probe of gap symmetry. The frequency dependence of the density of states and the temperature dependence of the thermodynamic properties obey different power laws for fields in the nodal and antinodal directions. The fourfold pattern is changed to a twofold pattern in orthorhombic materials.

A microscopic evaluation of the electrodynamic response for the vortex- lattice state of a model ultraclean s-wave superconductor is reported by W. A. Atkinson and A. H. MacDonald (Indiana). The calculation accounts self-consistently for both quasiparticle and collective order parameter response. In the absence of disorder and extrinsic pinning, the authors find a single dominant absorption peak at a frequency close to the cyclotron frequency. The authors then discuss the effects of homogeneous and inhomogeneous pinning on the optical conductivity and the penetration depth, and comment on the relationship between macroscopic and local penetration depths.

As noted by M. N. Kunchur (South Carolina) et al., the time-dependent Ginzburg-Landau approach qualitatively justifies the decomposition of the Hall angle in the mixed state into two terms, one proportional to field (as in a normal metal) and the other weakly dependent on field. The authors compare the theory with experimental data and find rough quantitative agreement.

The relaxation of a nonequilibrium normal domain in a superconductor has been studied by M. Ghinovker et al. (Bar-Ilan). The authors found both analytically and numerically that relaxation leads to nucleation of vortices and antivortices, which become pinned when pinning is strong.

The appearance of large-amplitude radio-frequency oscillations in high- sheet-resistance indium/indium-oxide films carrying nonuniform currents below the zero-field superconducting transition is reported by S. E. Hebboul et al. (Ohio State). The samples consisted of rectangular films, into which lines perpendicular to the current flow were cut, thereby producing highly nonuniform current flow around the tips of the lines. As the dc current increased above a threshold, several peaks were found to appear in the spectrum of the rf voltage vs. frequency, and these peaks grew and shifted to higher frequencies with increasing current. The authors attribute this effect to wave excitations in the density of current-depaired vortices and antivortices near the line tip.

Numerical studies supporting the idea that during nonuniform current flow in a two-dimensional superconductor, current-depaired vortices and antivortices can form a stable nonequilibrium vortex-density-wave state are presented in a preprint by S. E. Hebboul (Ohio State). The author found that a necessary condition for generating vortex density waves is a dc current distribution displaying a pronounced symmetrical dip along the direction of equipotential lines. Above a crossover current, the stationary densities of vortices and antivortices evolve into two coupled density waves, which travel in opposite directions.

The interaction of vortices in a quasi-one-dimensional array of Josephson junctions with small capacitance has been considered in a preprint by C. Bruder (Karlsruhe) et al. If the charging energy of a junction is of the order of the Josephson energy, the fluctuations of the superconducting order parameter in the system are considerable, and the vortices behave as quantum particles. The authors find that the interplay between the quantum nature of a vortex and the long-range interaction between vortices leads to the existence of a commensurate- incommensurate transition in a one-dimensional vortex lattice.

Films

The use of metal organic decomposition (MOD) to produce thick films of YBCO on SrTiO3 (STO) and LaAlO3 (LAO) single-crystal substrates is reported by S. Sathyamurthy and K. Salama (TCSUH). Films of thickness 0.5 micrometer were found to have critical current densities Jc in excess of 5 x 10^5 A/cm^2 at 77 K in zero field.

Direct peritectic growth (DPG) is a process in which textured YBCO thick films are deposited directly onto an unoriented silver alloy, with no buffer layer between the YBCO and the substrate. X. Wen (Cincinnati) et al. have used this method to produce thick YBCO films with transport Jc = 8 x 10^4 A/cm^2 at 77 K in zero magnetic field. The authors assert that the DPG method is capable of producing highly textured YBCO thick films, which are scalable to long lengths at low cost.

The microwave power-handling capabilities of YBCO thin superconducting films, up to 150 W of input power, have been investigated by J. Wosik et al. (TCSUH) using a 14 GHz shielded dielectric cavity. For all films, the authors found that the heating of weak links switched to the normal state is one of the major limitations for rf power handling.

Applications

A cylindrical YBCO single-domain superconducting cavity resonator for microwave applications has been made by D. Qu et al. (Cincinnati) using a net-shape melt-processing method. The authors report measurements of the quality factor (unloaded Q) as a function of annealing temperature and oxygen annealing history.

Levitation results are reported by Y. Postrekhin et al. (TCSUH) for high-temperature superconducting (HTS) trapped-field magnets made of disks of melt-textured YBa2Cu3O7-d prepared by the seeded directional solidification method. The authors found that the force between the magnet and the HTS trapped-field magnet depends on the polarity of the frozen magnetic field and can be positive or negative. The authors compared the levitation force between a magnet and a trapped-field magnet with that between the magnet and a zero-field-cooled high- temperature superconductor without trapped flux. The authors also investigated the stability of a levitation system based on trapped-field magnets by studying the amplitude-frequency characteristics of a system where a permanent magnet is attached to a soft cantilever beam and placed above the trapped-field magnet.

Theory

The feasibility of a perturbation expansion for Green's functions of the t-J model directly in terms of X-operators has been demonstrated by R. Zeyher and A. Greco (MPI-Stuttgart) using the Baym-Kadanoff functional method. As an application, the authors derive explicit expressions for the kernel Theta of the linearized equation for the superconducting order parameter in leading order of a 1/N expansion. The authors solve the linearized equation numerically on a square lattice taking instantaneous and retarded contributions into account.

Fixed-node Green's function Monte Carlo calculations have been performed by A. C. Cosentini (INFM and Roma) et al. for large (16 x 16) 2D Hubbard lattices, large interaction strengths (U = 10, 20, and 40), and many (15-20) densities between empty and half-filling. The authors show that for such large lattice sizes, the evaluation of the energy does not suffer from finite-size, shell, or boundary-condition effects, which are relevant for small systems. The energies do suffer, however, from a fixed-node bias.

A paper by Z. Y. Weng et al. (TCSUH) relates magnetic incommensurability to the intrinsic properties of the doped Mott insulator, described by the t-J model. The authors show that such incommensurability is a direct manifestation of the phase-string effect introduced by doped holes in both one- and two-dimensional cases. The magnetic incommensurate peaks in the dynamic spin susceptibility in momentum space are in agreement with neutron-scattering results in cuprate superconductors in both position and doping dependence. In particular, this incommensurate structure can naturally reconcile neutron-scattering and NMR experiments in the cuprates.

A mean-field treatment of the phase-string effect in the t-J model is presented in a preprint by Z. Y. Weng et al. (TCSUH). Such a theory is able to unite the antiferromagnetic (AF) phase at half-filling and the metallic phase at finite doping within a single theoretical framework. The low-temperature occurrence of AF long-range ordering at half-filling and superconducting condensation in the metallic phase are due to Bose condensations of spinons and holons, respectively, on top of a spin background described by bosonic resonating-valence-bond (RVB) pairing. The fact that both spinons and holons are bosons, as a result of the phase-string effect, represents a crucial difference from the conventional slave-boson and slave-fermion approaches.

An extended Hubbard model with nearest-neighbor correlated hopping and next-nearest-neighbor hopping t' is found by L. Arrachea (Rio) and A. A. Aligia (Bariloche) to be an effective model for the cuprate superconductors. Using a generalized Hartree-Fock BCS approximation, the authors find that for high enough t' and doping, antiferromagnetism is destroyed and the system exhibits d-wave superconductivity. The calculated superconducting critical temperature as a function of doping is in good agreement with experiment.

A preprint by O. Tchernyshyov (Columbia) points out an error in a 20- year-old paper by Sadovskii, who reported an exact solution of a model exhibiting a pseudogap in the electron energy spectrum of a one- dimensional conductor. The author also shows that antiferromagnetic fluctuations alone cannot explain the presence of a strong pseudogap in cuprate superconductors seen by local probes of the density of states, such as tunneling spectroscopy and NMR. Pairing fluctuations seem to be a necessary ingredient to explain the pseudogap at low frequencies.

The effect of order-parameter phase fluctuations on the single-particle properties of fermions in the underdoped cuprate superconductors has been studied by H.-J. Kwon and A. T. Dorsey (Florida) using a phenomenological low-energy theory. The authors identify the fermion - phase-field coupling as the Doppler shift of the quasiparticle spectrum induced by the fluctuating superfluid velocity, and they calculate the effect of these fluctuations on the fermion self-energy. Vortex-pair unbinding near the superconducting transition causes a significant broadening in the fermion spectral function, producing a pseudogap-like feature. The authors also discuss the specific heat and show that the phase-fluctuation effect is visible because of the short coherence length.

A simple model for the doped compound Nd2-xCexCuO4 is presented by R. E. Lagos (Rio Claro) et al. Using Hartree-Fock, the authors start from an impurity Anderson-like model and consider the magnetic splitting of the Nd 4f ground-state Kramers doublet due to exchange interactions with the ordered Cu moments. The results are in good agreement with the experimental data, yielding a Schottky anomaly peak for the specific heat that reduces in amplitude, broadens, and shifts to lower temperatures upon Ce doping.

Some applications of higher symmetry groups to condensed matter systems are discussed in a preprint by R. S. Markiewicz and M. T. Vaughn (Northeastern). The authors give special attention to the groups SO(n) (n = 4, 5, 6, and 8) in the two-dimensional Hubbard model and its generalizations, which model the high-Tc cuprate superconductors.

The attenuation of longitudinal ultrasonic waves in a clean two- dimensional d-wave superconductor has been considered by I. Vekhter (Guelph) et al. The authors show that the attenuation coefficient is linear in temperature at low temperatures for all in-plane directions of the propagation of the ultrasound, and that the coefficient of the linear term can be used to determine the parameters crucial for the low- temperature transport in these compounds.

The real-axis Eliashberg equations for the retarded electron-boson interaction have been solved by G. A. Ummarino and R. S. Gonnelli (Torino) for the case of d-wave symmetry for the pair wave function. The numerical simulations provide a good fit to the gap, critical temperature, and the density of states obtained recently in break- junction tunneling experiments.

A paper by A. H. Romero et al. (UC-San Diego) applies weak-coupling perturbation theory to the Holstein molecular crystal model in order to compute an electron-phonon correlation function characterizing the shape and size of the polaron lattice distortion in one, two, and three dimensions. The authors find that the width of the polaron thus determined disagrees in every dimension with some well-known characterizations of polarons, signaling in particular the breakdown of the adiabatic approximation and the characterizations of self-trapping associated with it.

Other Activities

The transport critical current Jc in a polycrystalline superconductor is known to be a hysteretic function of the applied magnetic field because of intragranular flux trapping. This effect has been observed by several groups, and attempts have been made to calculate the intergranular field H_i as a function of the applied field H_0 in terms of an effective geometrical demagnetization factor D. In general, a first-principles calculation of D is very difficult, and moreover D is not constant but rather a hysteretic function of H_0. A paper by M. N. Kunchur (South Carolina) and T. R. Askew (Kalamazoo and Argonne) describes a self-consistent scheme to extract D and H_i directly from the Jc(H_0) data. The authors apply this model to analyze data on sintered YBa2Cu3O7-d rods.

Measurements of the ac susceptibility of a ceramic high-temperature superconductor as a function of temperature, frequency, and ac-field amplitude are reported by S. Celibi (Karadeniz Technical University) et al. The sample was a rectangular bar-shaped sample of Bi1.84Pb0.34Sr1.91Ca2.03Cu3.06O10 prepared by the liquid ammonium nitrate method. The authors observed that as the frequency increased, the intra- and intergranular ac loss peaks moved to higher temperature, while as the ac-field amplitude increased, the peaks moved to lower temperature, indicating that the ac losses were due to both hysteretic bulk pinning losses and viscous (flux-flow) losses.

Overviews

A review chapter by G. Hilscher and H. Michor (Wien) summarizes the superconducting and normal properties of the borocarbide superconductors YNi2B2C and LuNi2B2C. The authors then review the magnetic properties of the RNi2B2C borocarbides with magnetic R ions, emphasizing the interplay between superconductivity and magnetism in these compounds (157 refs.).

A handbook chapter by W. Wong-Ng (NIST-Gaithersburg) illustrates representative examples of phase diagrams of the high-temperature superconductors, emphasizing the BaO-Y2O3-CuO, BaO-R2O3-CuO, and Bi2O3- PbO-SrO-CaO-CuO systems. The author also discusses the basic definitions of some frequently encountered terms, and describes experimental procedures for constructing phase diagrams (100 refs.).

An overview by J. Mannhart and H. Hilgenkamp (Augsburg) notes that the physics of interfaces involving complex superconductors is considerably richer and much less explored than the physics of interfaces and surfaces of conventional superconductors. The authors summarize a variety of unusual interface properties that arise from basic properties of unconventional superconductors, such as their pairing symmetry, small carrier densities, small coherence lengths, and band bending (87 refs.).

A review chapter by H. Schmidt and H. F. Braun (Bayreuth) summarizes a variety of investigations of borocarbide compounds relating their physical properties, such as superconductivity, magnetism, and their interplay, to their material parameters, such as chemical composition, lattice constants, long-range order, and transition-metal doping (81 refs.).

Contributed by John R. Clem

Contents: Preprints begin on page 7; Coming Events begin on page 12; Resources are on page 13; FYI is on page 13; Donors are listed on page 14; and an important renewal notice is on page 15.

High-Tc Update is available without charge to interested persons. Recipients are expected to participate in this information exchange by sending us preprints, reprints, meeting news, research news, etc. Contributions to defray the cost of newsletter printing and mailing are welcome.

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

Liliana Arrachea and A. A. Aligia, "d_[x^2-y^2] Superconductivity in a Generalized Hubbard Model." Departamento de Fisica, Pontificia Universidade Catolica-Rio, Caixa Postal 38071, Rio de Janeiro, 22452-970 RJ, BRAZIL; e-mail lilliana@leblon.fis.puc-rio.br; preprint also available at cond-mat@xxx.lanl.gov (#9809187).

D. K. Aswal, M. Shinmura, Y. Hayakawa, and M. Kumagawa, "In-Situ Measurement of the Growth Rate of YBa2Cu3Ox Single Crystals." Submitted to J. Cryst. Growth. Research Institute of Electronics, Shizuoka University, 3-5-1 Johoku, Hamamatsu 432-8011, JAPAN; telephone +81 53 478 1338; telefax +81 53 478 1338; e-mail roaswal@eng.shizuoka.ac.jp. Key words: peritectic crystallization, growth rate, high-temperature optical microscopy, YBa2Cu3Ox. 81.10.Fq; 74.72.Bk.

D. K. Aswal, M. Shinmura, Y. Hayakawa, and M. Kumagawa, "In-Situ Observation of Growth and Morphology of YBa2Cu3Ox Single Crystals." Submitted to J. Inorganic Mater. Research Institute of Electronics, Shizuoka University, 3-5-1 Johoku, Hamamatsu 432-8011, JAPAN; telephone +81 53 478 1338; telefax +81 53 478 1338; e-mail roaswal@eng.shizuoka.ac.jp. Key words: flux growth, peritectic crystallization, growth rate, growth morphology, high-temperature optical microscopy, YBa2Cu3Ox. 81.10.Fq; 74.72.Bk.

W. A. Atkinson and A. H. MacDonald, "Electrodynamics of an Ultra-Clean Vortex Lattice." Preprint #IUCM-012; submitted to Phys. Rev. Lett. Department of Physics, Indiana University, Bloomington, IN 47405; e-mail atkinson@gibbs.physics.indiana.edu; preprint also available at cond- mat@xxx.lanl.gov (#9809298). 74.25.Gz; 74.60.-w; 74.60.Ge; 74.25.Nf.

U. Balachandran, M. Lelovic, B. C. Prorok, N. G. Eror, V. Selvamanickam, and P. Haldar, "Advances in Fabrication of Ag-Clad Bi-2223 Superconductors." Submitted to Proc. of the 1998 Appl. Supercond. Conf. (ASC), Palm Desert, Calif., Sept. 13-18, 1998. Contact Janice Coble, Materials Science Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439; telephone (630) 252-5497; telefax (630) 252- 9595; e-mail coble@anl.gov.

G. Brandstaetter, M. C. Frischherz, L. Kratzwald, H. W. Weber, and A. E. Petrov, "Thermal-Neutron-Induced Gd-Point Defects in GdBa2Cu3O7-d Ceramics." To be published in Physica C. Contact H. W. Weber, Atominstitut der OEsterreichischen Universitaeten, Stadionallee 2, A- 1020 Wien, AUSTRIA; telephone +43 1 727 01 240; telefax +43 1 728 9220; e-mail weber@ati.ac.at. 74.60.Ge; 74.60.Jg; 74.62.-c; 74.72.Jt.

C. Bruder, L. I. Glazman, A. I. Larkin, J. E. Mooij, and A. van Oudenaarden, "Phase Transition in a Chain of Quantum Vortices." Department of Physics and Astronomy, University of Basel, Klingelbergstrasse 82, CH-4056 Basel, SWITZERLAND; e-mail in Karlsruhe, Germany bruder@tfp.physik.uni-karlsruhe.de; preprint also available at cond-mat@xxx.lanl.gov (#9809118).

V. Buntar, "Investigation of Inter- and Intragrain Currents in K3C60 Single Crystals." To be published in Physica C. Atominstitut der OEsterreichischen Universitaeten, Stadionallee 2, A-1020 Wien, AUSTRIA; telephone +43 1 72 701 296; telefax +43 1 72 89 220; e-mail buntar@ati.ac.at. Key words: fullerene superconductors, K3C60 crystals, critical current density, granularity.

V. Buntar, F. M. Sauerzopf, C. Krutzler, and H. W. Weber, "Evidence for Bulk Superconductivity in K3C60 Single Crystals." To be published in Phys. Rev. Lett. Atominstitut der OEsterreichischen Universitaeten, Stadionallee 2, A-1020 Wien, AUSTRIA; telephone +43 1 72 701 296; telefax +43 1 72 89 220; e-mail buntar@ati.ac.at. 74.25.Ha; 74.60.Jg; 74.70.Wz; 74.80.Bj.

A. Buzdin, "Vortex Structure in the Presence of Tilted Columnar Defects." To be published in JEPT Lett. Centre de Physique Theorique et Modelisation, Universite Bordeaux I, Rue du Solarium, F-33174 Gradignan Cedex, FRANCE.

S. Celebi, I. Karaca, E. Aksu, and A. Gencer, "Frequency Dependence of the Intergranular ac Loss Peak in a High-Tc Bi-(Pb)-Sr-Ca-Cu-O Bulk Superconductor." To be published in Physica C. Department of Physics, Faculty of Science and Arts, Karadeniz Technical University, 61080 Trabzon, TURKEY; telephone +90 462 325 8244; telefax +90 462 325 3195; e-mail celebi@risc01.ktu.edu.tr. Key words: ac susceptibility, ac losses, high-Tc Bi-(Pb)-Sr-Ca-Cu-O superconductors, activation energy. 74.60.Ge; 74.72.Fq.

S. J. Chen, C. F. Chang, H. L. Tsay, H. D. Yang, and J.-Y. Lin, "Magnetic Field Dependence of the Low-Temperature Specific Heat of La2- xSrxCuO4." To be published in Phys. Rev. B. Contact J.-Y. Lin, Institute of Physics, National Chiao Tung University, Hsinchu 300, Taiwan, REPUBLIC OF CHINA; telephone +886 3 573 1653; telefax +886 3 572 0728; e-mail ago@cc.nctu.edu.tw. 74.25.Bt; 74.72.Dn.

S.-K. Chin, A. K. Nguyen, and A. Sudbo, "First Order Melting Transition in Isotropic Extreme Type-II Superconductors." Department of Physics, Norwegian University of Science and Technology, Trondheim 7034, NORWAY; e-mail skc@phys.ntnu.no; preprint also available at cond- mat@xxx.lanl.gov (#9809115). 74.20.De; 74.76.-w.

G. Coletta, L. Gherardi, F. Goemoery, E. Cereda, V. Ottoboni, D. Daney, M. Maley, and S. Zannella, "Application of Electrical and Calorimetric Methods to the ac Loss Characterization of Cable Conductors." Presented at the 1998 Appl. Supercond. Conf. (ASC), Palm Desert, Calif., Sept. 13- 18, 1998. Contact E. Cereda, ENEL Ricerca, Via Reggio Emilia 39, I- 20090 Segrate Milano, ITALY; telephone +39 2 2167 2274; telefax +39 2 2167 2620; e-mail ezio.cereda@s1.cise.it.

A. C. Cosentini, M. Capone, L. Guidoni, and G. B. Bachelet, "Phase Separation in the 2D Hubbard Model: A Fixed-Node Quantum Monte Carlo Study." INFM and Department of Physics, University of Rome "La Sapienza", Piazzale A. Moro 2, I-00185 Rome, ITALY; G. B. Bachelet's e- mail giovanni.bachelet@roma1.infn.it; preprint also available at cond- mat@xxx.lanl.gov (#9801299). 71.10.Fd; 71.45.Lr; 74.20.-z.

X. Cui, F. A. List, D. M. Kroeger, A. Goyal, D. F. Lee, J. Mathis, E. D. Specht, P. M. Martin, R. Feenstra, D. T. Verebelyi, D. K. Christen, and M. Paranthaman, "Reel-to-Reel Continuous Deposition of Epitaxial CeO2 Buffer Layers on Biaxially Textured Ni Tapes by Electron Beam Evaporation." Submitted to IEEE Trans. Appl. Supercond.: Proc. of the 1998 Appl. Supercond. Conf. (ASC), Palm Desert, Calif., Sept. 13-18, 1998. Materials Science Section, Metals and Ceramics Division, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN 37831; telephone (423) 574-3719; telefax (423) 574-7659; e-mail cuix@orn1.gov.

M. Daumens, C. Meyers, and A. Buzdin, "Little-Parks Effect for Arbitrary Geometry: Fluctuations of the Magnetic Moment of Mesoscopic Loops." Centre de Physique Theorique et Modelisation, Unite associee au CNRS ESA 5468, Universite Bordeaux I, Rue du Solarium, F-33174 Gradignan Cedex, FRANCE.

Deniz Ertas, "Finite Temperature Depinning of a Flux Line from a Nonuniform Columnar Defect." Exxon Research and Engineering Company, Clinton Twp., Route 22 East, Annandale, NJ 08801; e-mail mdertas@erenj.com; preprint also available at cond-mat@xxx.lanl.gov (#9809132).

L. M. Fisher, A. V. Kalinov, S. E. Savel'ev, I. F. Voloshin, P. Haldar, H. W. Myron, and U. Balachandran, "ac Losses in Bi-2223 Tapes and in the 1-kA Transmission Line Model." Submitted to Proc. of the 1998 Appl. Supercond. Conf. (ASC), Palm Desert, Calif., Sept. 13-18, 1998. All- Russian Electrical Engineering Institute, Moscow, RUSSIA; preprint also available from Janice Coble, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439; telefax (708) 252-9595; e-mail janice_coble@qmgate.anl.gov.

K. Fujinami, H. Suematsu, M. Karppinen, and H. Yamauchi, "Effect of Overdoping on the Irreversibility Field and Critical Current Density of the HgBa2Ca2Cu3O8+d Superconductor." To be published in Physica C. Contact H. Yamauchi, Materials & Structures Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 227, JAPAN; telephone +81 45 924-5315; telefax +81 45 924-5365 or -5360; e-mail yamauchi@materia.titech.ac.jp.

L. V. Gasparov, P. Lemmens, N. N. Kolesnikov, and G. Guentherodt, "Electronic Raman Scattering in Tl2Ba2CuO6+d: Symmetry of the Order Parameter, Oxygen Doping Effects, and Normal State Scattering." Department of Physics, University of Florida, P.O. Box 118440, Gainesville, FL 32611-8440; telephone (352) 392-3776; telefax (352) 392- 3591; e-mail gasparov@phys.ufl.edu; preprint also available at cond- mat@xxx.lanl.gov (#9809159). 74.25.Gz; 74.72.Fq; 78.30.-j.

M. Ghinovker, I. Shapiro, and B. Ya. Shapiro, "Relaxation of Normal Spot in Type-II Superconductors." To be published in Europhys. Lett. Contact B. Ya. Shapiro, Institute of Superconductivity, Department of Physics, Bar-Ilan University, Ramat Gan 52900, ISRAEL. 74.20.De; 74.60.Ge.

K. C. Goretta, M. M. Cuber, L. R. Feng, B. L. Fisher, Ming Jiang, M. T. Lanagan, U. Balachandran, Y. Xu, and Ming Xu, "Microstructure and Properties of Bi-Sr-Ca-Cu-O with Additions of Nanometer-Scale Alumina." Submitted to IEEE Trans. Appl. Supercond.: Proc. of the 1998 Appl. Supercond. Conf. (ASC), Palm Desert, Calif., Sept. 13-18, 1998. Contact Janice Coble, Materials Science Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439; telephone (630) 252-5497; telefax (630) 252-9595; e-mail coble@anl.gov.

K. C. Goretta, P. Diko, Ming Jiang, M. M. Cuber, Ming Xu, J. E. Ostenson, and S. Sengupta, "Annealing and Mechanical Properties of Bulk Y-Ba-Cu-O." Submitted to IEEE Trans. Appl. Supercond.: Proc. of the 1998 Appl. Supercond. Conf. (ASC), Palm Desert, Calif., Sept. 13-18, 1998. Contact Janice Coble, Materials Science Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439; telephone (630) 252-5497; telefax (630) 252-9595; e-mail coble@anl.gov.

K. C. Goretta, D. S. Kupperman, S. Majumdar, M. W. Such, and Norimitsu Murayama, "Elastic Constants of Dense, Textured (Bi,Pb)2Sr2Ca2Cu3Oy." Submitted to Supercond. Sci. & Technol. Contact Janice Coble, Materials Science Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439; telephone (630) 252-5497; telefax (630) 252-9595; e- mail coble@anl.gov.

D. A. Gorokhov and G. Blatter, "Metastability of (d+n)-Dimensional Elastic Manifolds." Preprint #ETH-TH/98-10; to be published in Phys. Rev. B. Theoretische Physik, ETH-Hoenggerberg, CH-8093 Zurich, SWITZERLAND; e-mail gorokhov@itp.phys.ethz.ch; preprint also available at cond-mat@xxx.lanl.gov (#9809141). 64.60.My; 64.60.Qb; 74.60.Ge.

J. Kent Harbaugh and D. Stroud, "Critical Currents of Josephson-Coupled Wire Arrays." Department of Physics, Ohio State University, 174 W. 18th Avenue, Columbus, OH 43210-1106; e-mail jkenth@pacific.mps.ohio- state.edu; preprint also available at cond-mat@xxx.lanl.gov (#9809279).

Saad E. Hebboul, "A New Nonequilibrium Vortex-Density-Wave State in Two- Dimensional Superconductors." Submitted to Phys. Rev. Lett. Department of Physics, Ohio State University, Columbus, OH 43210; e-mail hebboul@mps.ohio-state.edu. 74.40.+k; 74.76.-w; 74.80.-g; 74.60.Ge.

S. E. Hebboul, D. P. Johnson, and M. Rokhlin, "Radio-Frequency Oscillations in Two-Dimensional Superconducting In/InOx: A Possible Evidence for Vortex Density Waves." Submitted to Phys. Rev. Lett. Department of Physics, Ohio State University, Columbus, OH 43210; e-mail hebboul@mps.ohio-state.edu. 74.40.+k; 74.76.-w; 74.80.-g; 74.60.Ge.

Gerfried Hilscher and Herwig Michor, "Superconductivity and Magnetism in Quaternary Borocarbides and Boronitrides." To be published in Studies of High Temp. Supercond., Vol. 26-27, edited by A. Narlikar (Nova Science Publishers, New York, 1998). Institut fuer Experimentalphysik, Technische Universitaet Wien, Wiedner Hauptstrasse 8-10, A-1040 Wien, AUSTRIA; telefax +43 1 586 3191; e-mail friedl@xphys.tuwien.ac.at.

Y. B. Huang, M. Dhalle, G. Witz, F. Marti, E. Giannini, E. Walker, R. Passerini, A. Polcari, S. Clerc, K. Kwasnitza, and R. Fluekiger, "Development of Bi(2223) Multifilamentary Tapes with Low ac Losses." To be published in J. Supercond. Group of Applied Physics, University of Geneva, 20 rue l'Ecole de Medecine, CH-1211 Geneva 4, SWITZERLAND; telephone +41 22 702 6593; telefax +41 22 781 0980; e-mail huang@sc2a.unige.ch. Key words: oxide barrier, ac losses, mechanical property, Bi(2223) tape, fabrication.

A. N. Iyer, M. K. Mironova, S. Stolbov, C. Vipulanandan, K. Salama, and U. Balachandran, "Current Transport and Microstructural Evolution in BSCCO Tapes Fabricated by Groove Rolling." Preprint #98:087; submitted to IEEE Trans. Appl. Supercond.: Proc. of the 1998 Appl. Supercond. Conf. (ASC), Palm Desert, Calif., Sept. 13-18, 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.

V. V. Kabanov, J. Demsar, B. Podobnik, and D. Mihailovic, "Quasiparticle Relaxation Dynamics in Superconductors with Different Gap Structures: Theory and Experiments on YBa2Cu3O7-d." To be published in Phys. Rev. B. Jozef Stefan Institute, Jamova 39, 1001 Ljubljana, SLOVENIA; e-mail viktor.kabanov@ijs.si; preprint also available at cond-mat@xxx.lanl.gov (#9809333).

Ali E. Khalil, "Non-Isothermal Conditions and the Scaling of Activation Energy in High Temperature Superconductors." To be published in Phys. Lett. A. Department of Physics, University of Bahrain, P.O. Box 32038, Isa Town, BAHRAIN; telephone +973 681234.

A. K. Kienappel and M. A. Moore, "Numerical Studies of the Phase Diagram of Layered Type II Superconductors in a Magnetic Field." Submitted to Phys. Rev. B. Contact M. A. Moore, Department of Physics, University of Manchester, Manchester, M13 9PL, UNITED KINGDOM; telephone +44 161 275 4200; telefax +44 161 275 4218; e-mail m.a.moore@man.ac.uk; preprint also available at cond-mat@xxx.lanl.gov (#9809317). 74.20.De; 74.25.Dw; 74.25.Ha.

Chan-Joong Kim, Ki-Baik Kim, Young A. Jee, Il-Hyun Kuk, and Gye-Won Hong, "Effects of the Heating Rate on Conversion of the Precursor Powders Used for Melt Processes into YBa2Cu3O7-y." To be published in J. Mater. Res. Superconductivity Research Laboratory, Korea Atomic Energy Research Institute, P.O. Box 105, Yusong, Taejon 305-600, SOUTH KOREA; telephone +82 42 868 8908; telefax +82 42 862 5496; e-mail cjkim2@nanum.kaeri.re.kr.

M. N. Kunchur and T. R. Askew, "Hysteretic Internal Fields and Critical Currents in Polycrystalline Superconductors." Submitted to J. Appl. Phys. Department of Physics and Astronomy, University of South Carolina, Columbia, SC 29208; telephone (803) 777-1907; telefax (803) 777-3065; e-mail kunchur@cosm.sc.edu. 74.60.Jg; 74.60.Ge.

M. N. Kunchur, D. K. Christen, and B. I. Ivlev, "Decomposition of the Hall Angle in the Mixed State of Superconductors." To be published in Physica C. Department of Physics and Astronomy, University of South Carolina, Columbia, SC 29208; telephone (803) 777-1907; telefax (803) 777-3065; e-mail kunchur@cosm.sc.edu. Key words: superconductivity, mixed state, Hall effect, vortices. 74.25.Fy; 74.25.-q; 74.60.Ec; 74.60.Ge.

Hyok-Jon Kwon and Alan T. Dorsey, "The Effect of Phase Fluctuations on the Single-Particle Properties of the Underdoped Cuprates." Submitted to Phys. Rev. B. Department of Physics, University of Florida, Gainesville, FL 32611-8440; e-mail hjk@phys.ufl.edu; preprint also available at cond-mat@xxx.lanl.gov (#9809225). 74.20.-z; 74.25.-q; 74.40.+k; 74.72.-h.

R. E. Lagos, A.C.M. Stein-Barana, and G. G. Cabrera, "A Model for the Schottky Anomaly in Metallic Nd2-yCeyCuO4." Departamento de Fisica, IGCE, Universidade Estadual Paulista (UNESP), C.P. 178, Rio Claro 13500- 970 SP, BRAZIL; telephone +55 19 526 2238; telefax +55 19 534 8250; e- mail monaco@laplace.igce.unesp.br; preprint also available at cond- mat@xxx.lanl.gov (#9807337). Key words: Schottky anomalies, rare earths, Anderson model, cuprate oxides. 65.40.Hq; 75.20.Hr; 74.72.Jt.

M. T. Lanagan, K. C. Goretta, D. K. Walter, R. B. Poeppel, R. Troendly, M. J. McNallan, and S. Danyluk, "Near-Net-Shape Fabrication of Continuous Ag-Clad Bi-Based Superconductors." Presented at the 1998 Appl. Supercond. Conf. (ASC), Palm Desert, Calif., Sept. 13-18, 1998. Contact Janice Coble, Materials Science Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439; telephone (630) 252-5497; telefax (630) 252-9595; e-mail coble@anl.gov.

V. V. Luparev, G. M. Kuz'micheva, and E. P. Klybov, "Crystal Structure of New Phase (Hg,Ce,Cu)(Sr,Y)2(Y,Ce)2Cu2O8+d (1222) and Connection with an Analogous Structure." To be published in Zh. Neorgan. Khimii. Contact G. M. Kuz'micheva, Department of Solid State Physics and Chemistry, State M.V. Lomonosov Academy of Fine Chemical Technology, 86 pr. Vernadsky, Moscow 117571, RUSSIA; telephone +7 095 248 0762; e-mail kuz7micheva@glasnet.ru. (Paper In Russian.)

J. Mannhart and H. Hilgenkamp, "Interfaces Involving Complex Superconductors." Experimentalphysik VI, Center for Electronic Correlations and Magnetism, Institute of Physics, University of Augsburg, Universitaetsstr. 1, D-86135 Augsburg, GERMANY; telephone +49 821 598 3650; telefax +49 821 598 3652; e-mail jochen.mannhart@physik.uni-augsburg.de.

R. S. Markiewicz and M. T. Vaughn, "Higher Symmetries in Condensed Matter Physics." Department of Physics, Northeastern University, Boston, MA 02115; e-mail markiewic@neu.edu; preprint also available at cond-mat@xxx.lanl.gov (#9809119).

N. N. Merchant, D. J. Miller, V. A. Maroni, R. D. Parrella, Q. Li, M. W. Rupich, W. L. Carter, and G. N. Riley, Jr., "Phase Stability and Grain Growth in an Ag/Bi-2223 Composite Conductor Prepared Using Fine-Grained Bi-2223 as a Precursor." Submitted to IEEE Trans. Appl. Supercond.: Proc. of the 1998 Appl. Supercond. Conf. (ASC), Palm Desert, Calif., Sept. 13-18, 1998. Contact Janice Coble, Materials Science Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439; telephone (630) 252-5497; telefax (630) 252-9595; e-mail coble@anl.gov.

N. Morozov, M. P. Maley, L. N. Bulaevskii, V. Thorsmolle, A. E. Koshelev, A. Petrean, and W. K. Kwok, "Structure of Vortex Liquid Phase in Irradiated Bi2Sr2CaCu2O8-d Crystals." Submitted to Phys. Rev. Lett. Superconductivity Technology Center, Los Alamos National Laboratory, K763, Los Alamos, NM 87545; e-mail morozov@lanl.gov; preprint also available at cond-mat@xxx.lanl.gov (#9809165). 74.60.Ge; 74.25.Fy; 74.62.Dh.

M. Muralidhar, M. R. Koblischka, T. Saitoh, and M. Murakami, "Microstructure and Pinning in High-Tc and Large-Jc (Nd,Eu,Gd)-123 Superconductors Prepared by OCMG Process." To be published in Supercond. Sci. & Technol. Superconductivity Research Laboratory, International Superconductivity Technology Center (ISTEC), 3-35-2 Iioka- Shinden, Morioka, Iwate 020-0852, JAPAN; telephone +81 19 635-9015 or -9016; telefax +81 19 635-9017; e-mail miryala@istec.or.jp. Key words: melt processing, (Nd,Eu,Gd)Ba2Cu3Oy, 211 inclusions, refinement, Pt addition, CeO2 addition, microstructure, large Jc. 74.60.Ge; 74.60.Jg; 74.62.Dh.

M. Muralidhar and M. Murakami, "Effects of (Nd,Eu,Gd)211 and Platinum Additions on the Jc-B Properties of (Nd,Eu,Gd)123." Presented at the 1998 Int. Workshop on Supercond.: Mater. and Technol. Issues for HTS Wires and Bulk Applications, Okinawa, Japan, July 12-15, 1998. Superconductivity Research Laboratory, International Superconductivity Technology Center (ISTEC), 3-35-2 Iioka-Shinden, Morioka, Iwate 020- 0852, JAPAN; telephone +81 19 635-9015 or -9016; telefax +81 19 635- 9017; e-mail miryala@istec.or.jp.

Paul Muzikar, "Vortex Lines and Field Reversal in Anisotropic Superconductors." Department of Physics, Purdue University, West Lafayette, IN 47907.

M. R. Norman, M. Randeria, H. Ding, and J. C. Campuzano, "Photoelectron Escape Depth and Inelastic Secondaries in High Temperature Superconductors." Submitted to Phys. Rev. B. Contact Janice Coble, Materials Science Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439; telephone (630) 252-5497; telefax (630) 252- 9595; e-mail coble@anl.gov; preprint also available at cond- mat@xxx.lanl.gov (#9809206). 71.25.Hc; 74.25.Jb; 74.72.Hs; 79.60.Bm.

F. Onufrieva and P. Pfeuty, "Normal State Pseudogap and (pi,0) Feature in the Underdoped High-Tc Cuprates: A Microscopical Theory." Laboratoire Leon Brillouin, CE-Saclay, F-91191 Gif-sur-Yvette, FRANCE; e-mail onufri@11b.saclay.cea.fr; preprint also available at cond- mat@xxx.lanl.gov (#9807268).

Y. Postrekhin, K. B. Ma, J. H. Yu, and W. K. Chu, "Interaction Between a Permanent Magnet and an HTS Trapped Field Magnet." Preprint #98:090; submitted to IEEE Trans. Appl. Supercond.: Proc. of the 1998 Appl. Supercond. Conf. (ASC), Palm Desert, Calif., Sept. 13-18, 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.

Dehui Qu, Brian A. Tent, Donglu Shi, Shih-Lin Lu, Altan M. Ferendeci, and David Mast, "Effect of Oxygen on rf Properties in a Single Domain YBCO Cavity Resonator for Microwave Applications." Department of Materials Science and Engineering, University of Cincinnati, Cincinnati, OH 45211.

Aldo H. Romero, David W. Brown, and Katja Lindenberg, "Exact Weak- Coupling Radius of the Holstein Polaron in One, Two, and Three Dimensions." Submitted to Phys. Rev. Lett. Department of Chemistry, University of California at San Diego, Mail Code 0340, 9500 Gilman Drive, La Jolla, CA 92093; telephone (619) 534-5658; telefax (619) 534- 7244; e-mail aromero@hypatia.ucsd.edu; preprint also available at cond- mat@xxx.lanl.gov (#9808348). 71.38.+i; 71.15.-m; 71.35.Aa; 72.90.+y.

F. Sandiumenge, N. Vilalta, J. Rabier, and X. Obradors, "Three Dimensional Dislocation Substructure in NdBa2Cu3Oy." To be published in Appl. Phys. Lett. Institut de Ciencia de Materials de Barcelona, (CSIC), Campus de la Universitat Autonoma de Barcelona, E-08193 Bellaterra, Catalunya, SPAIN; telephone +34 3 580 1853; telefax +34 3 580 5729. 61.72.Ff; 61.72.Nn; 74.72.Bk; 74.60.Ge.

S. Sathyamurthy and K. Salama, "Processing of Y123 Coated Conductors Using Metal Organic Decomposition." Preprint #98:086; submitted to IEEE Trans. Appl. Supercond.: Proc. of the 1998 Appl. Supercond. Conf. (ASC), Palm Desert, Calif., Sept. 13-18, 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.

N. Savvides, A. Katsaros, A. Thorley, J. Herrmann, G. McCaughey, R. Zhao, F. Darmann, and M. Apperley, "Critical Current and Magnetic Field Performance of Bi-2223/Ag Composite Superconducting Tapes." Submitted to IEEE Trans. Appl. Supercond.: Proc. of the 1998 Appl. Supercond. Conf. (ASC), Palm Desert, Calif., Sept. 13-18, 1998. CSIRO Telecommunications and Industrial Physics, Bradfield Road, West Lindfield, P.O. Box 218, Lindfield NSW 2070, AUSTRALIA; telephone +61 2 9413 7359; telefax +61 2 9413 7631; e-mail nick.savvides@tip.csiro.au.

H. Schmidt and H. F. Braun, "Dependence of Superconductivity and Magnetism on Material Parameters in Quaternary Borocarbides." To be published in Studies of High Temp. Supercond., Vol. 26, edited by A. Narlikar (Nova Science Publishers, New York, 1998). Physikalisches Institut, Universitaet Bayreuth, D-95440 Bayreuth, GERMANY.

H. Shibata and T. Yamada, "Double Josephson Plasma Resonance in T*-Phase SmLa1-xSrxCuO4-d." To be published in Phys. Rev. Lett. NTT Basic Research Laboratories, 3-1 Morinosato Wakamiya, Atsugi-shi, Kanagawa 243-0198, JAPAN; telephone +81 462 40 3356; telefax +81 462 40 4675; e- mail shibata@will.brl.ntt.co.jp. 74.25.Gz; 74.72.Jt; 74.80.Dm.

Qimiao Si, "Spin Injection into a Luttinger Liquid." To be published in Phys, Rev. Lett. Department of Physics, Rice University, Houston, TX 77251-1892. 71.10.Hf; 73.40.-c; 71.27.+a; 72.15.Gd.

Oleg Tchernyshyov, "Pseudogap in 1D Revisited." To be published in Phys. Rev. B. School of Natural Sciences, Institute for Advanced Study, Princeton, NJ 08540; preprint also available at cond-mat@xxx.lanl.gov (#9804318).

G. A. Ummarino and R. S. Gonnelli, "Real-Axis Direct Solution of the d- Wave Eliashberg Equations and the Tunneling Density of States in Optimally Doped Bi2Sr2CaCu2O8+x." To be published in Phys. Rev. B. INFM-Dipartimento di Fisica, Politecnico di Torino, I-10129 Torino, ITALY; e-mail gonnelli@polito.it; preprint also available at cond- mat@xxx.lanl.gov (#9809262). 74.50.+r; 74.20.-z; 74.72.Hs.

I. Vekhter, P. J. Hirschfeld, J. P. Carbotte, and E. J. Nicol, "Anisotropic Thermodynamics of d-Wave Superconductors in the Vortex State." Department of Physics, University of Guelph, Guelph, Ontario, CANADA N1G 2W1; e-mail vekhter@anik.physics.uoguelph.ca; preprint also available at cond-mat@xxx.lanl.gov (#9809302).

I. Vekhter, E. J. Nicol, and J. P. Carbotte, "Ultrasonic Attenuation in Clean d-Wave Superconductors." Department of Physics, University of Guelph, Guelph, Ontario, CANADA N1G 2W1; e-mail vekhter@anik.physics.uoguelph.ca; preprint also available at cond- mat@xxx.lanl.gov (#9808178).

G. Villard, D. Pelloquin, and A. Maignan, "Doping Dependence of the In- Plane Penetration Depth and Fishtail in Bi2Sr2Ca1-xYxCu2O8+d Single Crystals." To be published in Phys. Rev. B. Laboratoire CRISMAT, ISMRA et Universite de Caen, UMR 6508 associee au CNRS, 6 Boulevard du Marechal Juin, F-14050 Caen Cedex, FRANCE; telephone +33 2 31 45 2916; telefax +33 2 31 95 1600; e-mail physol@crismat.ismra.fr. 74.72.Hs; 74.25.Ha; 74.62.Dh; 74.60.Ge.

R. Weinstein, D. Parks, R.-P. Sawh, A. Gandini, W. Hennig, S. X. Dou, and B. Zeimetz, "A Non-Destructive, Non-Contact, Continuous Quality Test for Ag-BiSCCO Tape." Submitted to Physica C. Beam Particle Dynamics Group and TCSUH, University of Houston, Houston, TX 77204-5506. Key words: HTS tape characterization, quality evaluation of Ag-BiSCCO tape, trapped field in BiSCCO tape.

Xuejun Wen, Dehui Qu, Brian A. Tent, Donglu Shi, Michael Tomsic, and Marvis White, "Direct Deposition of c-Axis Textured YBCO Thick Film on Unoriented Metallic Substrate for the Development of Long Superconducting Tapes." Presented at the 1998 Appl. Supercond. Conf. (ASC), Palm Desert, Calif., Sept. 13-18, 1998. Department of Materials Science and Engineering, University of Cincinnati, Cincinnati, OH 45211.

Z. Y. Weng, D. N. Sheng, and C. S. Ting, "Magnetic Incommensurability in Doped Mott Insulator." 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; preprint also available at cond-mat@xxx.lanl.gov (#9809363). 71.27.+a; 75.10.Jm; 74.72.-h.

Z. Y. Weng, D. N. Sheng, and C. S. Ting, "Mean-Field Description of Phase String Effect in the t-J Model." 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; preprint also available at cond- mat@xxx.lanl.gov (#9809362). 71.27.+a; 74.20.Mn; 75.10.Jm; 74.72.-h.

Winnie Wong-Ng, "Phase Diagrams of High Tc Superconductors." To be published in Handbook of Supercond., edited by C. Poole (Academic Press, 1998). A215 MATLS, National Institute of Standards and Technology, Gaithersburg, MD 20899; telephone (301) 975-5791; telefax (301) 975- 5334; e-mail winnie.wong-ng@nist.gov.

Winnie Wong-Ng, Lawrence P. Cook, A. Kearsley, and W. Greenwood, "Phase Equilibria of High Tc Superconductors in the (Bi,Pb)-Sr-Ca-Cu-O System." To be published in the Proc. of the 8th U.S.-Japan Workshop on High Temp. Supercond., Tallahassee, Fla., Dec. 8-10, 1997. A215 MATLS, National Institute of Standards and Technology, Gaithersburg, MD 20899; telephone (301) 975-5791; telefax (301) 975-5334; e-mail winnie.wong- ng@nist.gov.

W. Wong-Ng, L. P. Cook, A. Kearsley, C. Lawrence, and W. Greenwood, "Primary Phase Field of the Pb-Doped 2223 High Tc Superconductor in the (Bi,Pb)-Sr-Ca-Cu-O System." To be published in J. NIST Res. A215 MATLS, National Institute of Standards and Technology, Gaithersburg, MD 20899; telephone (301) 975-5791; telefax (301) 975-5334; e-mail winnie.wong-ng@nist.gov.

W. Wong-Ng, J. A. Kaduk, R. A. Young, F. Jiang, L. J. Swartzendruber, and H. J. Brown, "Investigation of (Sr4-dCad)PtO6 Using X-ray Rietveld Refinement." To be published in Powder Diffraction. A215 MATLS, National Institute of Standards and Technology, Gaithersburg, MD 20899; telephone (301) 975-5791; telefax (301) 975-5334; e-mail winnie.wong- ng@nist.gov.

J. Wosik, L. M. Xie, R. Grabovickic, T. Hogan, and S. A. Long, "Microwave Power Handling Capability of HTS Superconducting Thin Films: Weak Links and Thermal Effects Induced Limitation." Preprint #98:089; submitted to IEEE Trans. Appl. Supercond.: Proc. of the 1998 Appl. Supercond. Conf. (ASC), Palm Desert, Calif., Sept. 13-18, 1998. Texas Center for Superconductivity and Department of Electrical and Computer Engineering, University of Houston, Houston, TX 77204; telephone (713) 743-8200; telefax (713) 743-8201; e-mail preprints@www.tcs.uh.edu.

R. Zeyher and A. Greco, "Effective Interactions and Superconductivity in the t-J Model in the Large-N Limit." Max-Planck-Institut fuer Festkoerperforschung, Heisenbergstrasse 1, D-70569 Stuttgart, GERMANY; e-mail zeyher@greta5.mpi-stuttgart.mpg.de; preprint also available at cond-mat@xxx.lanl.gov (#9808283). 74.20.-z; 74.20.Mn.

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

Oct. 23 - 25, 1998: Joint Midwest Solid State Conference and Solid State Theory Conference, Scheman Building, Ames, Iowa. Two traditional Midwest solid state conferences will be held: the Midwest Solid State Conference, which in the past has included mainly experimental work, and the Midwest Solid State Theory Conference. Selection of invited speakers covers a wide range of topics both in theory and experiment. Abstract deadline, Oct. 15, 1998; registration deadline, Oct. 16, 1998. For information, contact Konnie Willie-Kennicker, Conference Secretary, A109 Physics, Department of Physics and Astronomy, Iowa State University, Ames, IA 50011-3020; phone (515) 294-3481; fax (515) 294- 0689; e-mail kkennick@ameslab.gov; Web site http://cmpweb109.ameslab.gov/conference.

April 8 - 9, 1999: Workshop on ac Losses (WACL 99), EPRI, Palo Alto, Calif. Two-day workshop will cover theoretical and experimental research on power-line-frequency (50-60 Hz) ac losses in high- temperature superconductors, and the influence such losses have on the design of HTS devices for electric power applications. As in previous EPRI-sponsored workshops held in 1995 and 1997, the program will consist of talks, posters, and workshop discussions. No registration fee, but attendance limited to 65 participants. For further information, contact Kathleen Lyons, Conference Coordinator, EPRI, 3412 Hillview Ave., Palo Alto, CA 94304; telephone (650) 855-2656; telefax (650) 855-8997; e-mail klyons@epri.com.

June 14 - 18, 1999: Specialized Colloque AMPERE: EPR, NMR, NQR in Solid State Physics -- Recent Trends, Dipartimento di Fisica, Pisa, Italy. Meeting will deal with recent magnetic-resonance studies in strongly correlated systems (such as charge-doped transition metals oxides, heavy fermions, and high-temperature superconductors) at phase transitions in incommensurate and/or disordered systems and glassy materials, and in fullerenes and fullerites. Also included will be particular aspects in strong magnetic fields and nonlinear effects, as well as studies in new branches of magnetism such as quantum magnetism in planar antiferromagnets, spin ladders, and chains or magnetic clusters. Recent experimental developments (including high-field/high- frequency EPR spectroscopy and magnetic resonance microscopy) and their applications to the study of new magnetic materials will be discussed. Intention is to cast these topics in a unified frame based on the common experimental approaches with resonance and relaxation techniques, with an effort towards unifying aspects and methodology at an advanced level. For further information, contact Conference Secretariat, IFAM- CNR, Via del Giardino, 7, I-56127 Pisa, Italy; telefax +39 50 3139035; e-mail ampere@ifam.pi.cnr.it; Web site http://www.ifam.pi.cnr.it/ampere.html.

June 28 - July 3, 1999: World Electrotechnical Congress and Exhibition (WELC-99), Moscow, Russia. Plenary sessions and fourteen technical sessions to be organized at various locations in Moscow. Subsection on Electrical Engineering Equipment for Transmission and Distribution of Electric Energy will include session on HTSC applications in power engineering. For information, contact WELC-99, Section 2 Organizing Committee, 12 Krasnokazarmennay Street, VEI, 111250 Moscow, Russia; telefax +7 095-362 5617 or -362 5503; e-mail agilim@vei.ru or finareva@vei.ru.

RESOURCES

Information

Books: The Physics of Composite Superconductors, by A. V. Gurevich, R. G. Mints, and A. L. Rakhmanov. Composite superconductors offer a solution to a wide range of problems, including thermomagnetic instability, instability of the superconducting state with respect to strong pulsed perturbations, heat release under varying external conditions, and inadequate strength and plasticity. The macroscopic properties of composite superconductors, and the processes that occur in them, are studied in the rapidly developing subject of the physics of composite superconductors. This monograph presents a unified account of the subject and covers all important aspects of composite superconductors such as structure and physical characteristics, losses, stability of the critical state, superconducting-to-normal transition, and high-temperature superconductivity. Publ. 1997; 348 pp.; price $112.50; ISBN 1-57600-066-5. Contact Begell House Publishers, 79 Madison Avenue, New York, NY 10016; telephone (212) 725-1999; telefax (212) 213-8368; e-mail begellhouse@worldnet.att.net; Web site www.begellhouse.com.

New Book: The Superconducting State in Magnetic Fields -- Special Topics and New Trends, edited by Carlos A. R. Sa de Melo. This volume is a collection of short review articles written by leading international experts on the superconducting state in magnetic fields, a rapidly developing area. The philosophy of the book is to emphasize the importance of having experimental and theoretical works side by side. Every effort has been made to match each experimental article with a corresponding theoretical article. The selection of materials includes special topics, new effects, and new trends concerning superconductors in low and high magnetic fields. Special topics and new trends include quantum and classical melting of the vortex lattice, new vortex lattice symmetries, vortex core states, nonlinear Meissner effect, symmetry of the order parameter in high-temperature superconductors, and superconductors in high magnetic fields. Targeted at a broad audience, including graduate students, postdocs, and other researchers active or interested in this field. Publ. 1998; 340 pp.; price US$78/Pounds 54, US$38/Pounds 26 (pbk); ISBN 981-02-3374-4 or ISBN 981-02-3566-6 (pbk). Contact World Scientific Publishing Co., Inc., 1060 Main Street, River Edge, NJ 07661; telephone (800) 227-7562 or (201) 487-9655; telefax (201) 487-9656; e-mail wspc@wspc.com; Web site http://www.wspc.com/.

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

Position available: Postdoctoral fellowship at the CSIRO Telecommunications and Industrial Physics in Sydney, NSW, Australia. Applicant to undertake basic research on critical current limitations and flux dynamics of high-temperature superconductors to improve the current-carrying capability in strong magnetic fields. Ph.D. in condensed matter or other related areas of physics, electrical engineering, or materials science required. Three-year term. Salary: 44 K to 50 K (Australian dollars) + superannuation. Application deadline, December 4, 1998. For a copy of selection criteria and duty statement, contact Geoff Hall, telephone +61 2 9413 7450, telefax +61 2 9413 7631, e-mail geoff.hall@tip.csiro.au. Applicants should quote reference number AS98/13, include relevant personal particulars, including qualifications and experience, and send applications to Human Resources Department, CSIRO Telecommunications & Industrial Physics, P.O. Box 218, Lindfield, NSW 2070, Australia.

The World Laboratory announces a scholarship named in honor of E. R. Caianiello to be awarded annually to a young physicist. The scholarship will be tenable at the International Institute for Advanced Scientific Studies "E. R. Caianiello" in Vietri sul Mare, Salerno, Italy, and at the Department of Physical Sciences "E. R. Caianiello" of the Salerno University. Open to candidates from developing countries working in condensed-matter physics and quantum-field theory. Date of availability: September 1999 (negotiable); duration: 12 months; amount of the scholarship: approximately 1300 Swiss francs per month. Application deadline, December 31, 1998. Prospective candidates are invited to send their CV, list of publications, and two letters of recommendation to Prof. F. Mancini, Dipartimento di Scienze Fisiche "E. R. Caianiello", Universita' degli Studi di Salerno, Via S. Allende, I- 84081 Baronissi (SA), Italy; telephone +39 89 965322; telefax +39 89 965275; e-mail mancini@vaxsa.csied.unisa.it.

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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.

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High-Tc Update, Vol. 12, #20, Oct. 15, 1998.