Published for the Division of Materials Sciences, Office of Basic Energy Sciences, USDOE, under Contract W-7405-eng-82 with the Ames Laboratory, Iowa State University. Funded by DMS/BES/USDOE, ARPA, and other agencies, organizations, and individuals.
The e-mail version of the High-Tc Update is sent to e-mail addresses accessible over INTERNET addresses. You can send e-mail messages to the editor at MITRA@AMESLAB.GOV or MITRA@IASTATE.EDU.
The High-Tc Update web page is located at the URL http://www.iitap.iastate.edu/htcu/htcu.html
PLEASE NOTE: Issues of High-Tc Update can be sent as an attachement (Word document). (This version preserves the Greek letters, special characters, accents, etc.) If you are interested in the the attached Word file instead of the ASCII text version, please contact the editor.
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:
YBCO Coated Conductors
The E-J characteristics and resistive transitions of a YBa2Cu3O7-d (YBCO) film deposited onto polycrystalline Hastelloy with a biaxially aligned yttria-stabilized-zirconia (YSZ) buffer layer produced by inclined-substrate pulsed-laser deposition (ISPLD) have been examined by R. A. Doyle et al. (IRC-Cambridge). The YSZ films were fabricated on electrochemically polished Hastelloy-C substrates using a 248 nm KrF excimer laser and inclining the substrate normal by 55 degrees relative to the plume axis. The substrate inclination resulted in alignment of the YSZ layer within the surface plane, with a full width at half maximum (FWHM) less than 30 degrees, and c-axis orientation [(001) direction normal to the surface plane]. YBCO films of thickness 1 micrometer were deposited on the YSZ by pulsed-laser deposition (PLD). The YBCO films had better in-plane alignment (18 degrees FWHM) than the underlying buffer layer but had about a 5 degrees c-axis misalignment.
The authors studied the field dependence of the critical current and irreversibility line of the YBCO films for magnetic fields aligned parallel and perpendicular to the ab-planes. The critical current at 77 K was found to be 8 x 10^4 A/cm^2 in zero field and 6 x 10^3 A/cm^2 in a 6 T field parallel to the ab-planes. The angular dependence of the E-J characteristics suggests that both intrinsic pinning and pinning by twin planes or low-angle grain boundaries play an important role. The authors note that while the properties of these films are still not as attractive as those obtained using ion-beam-assisted deposition (IBAD), the present results show that the ISPLD sample-preparation method is able to produce films with properties that are superior to those of Bi- 2223 conductors at 77 K in high magnetic fields.
The strain sensitivity of YBCO coated conductors has been investigated by C.L.H. Thieme (American Superconductor Corporation) et al. via measurements of the critical current density Jc in self-field at 77 K as a function of applied tensile strain. The YBCO coated conductor used an Inconel substrate. One side was coated with a biaxially textured YSZ buffer layer using IBAD, and subsequently was coated with a 2.5 micrometer YBCO layer by PLD. The superconductor was then coated with a silver cap layer. The authors found that at 77 K, a strain of up to 0.5% does not change Jc by more than 3%. This strain dependence is better than the tensile-stress dependence when samples are bent at room temperature.
A preprint by M. W. Rupich (American Superconductor Corporation) et al. reports the properties of metal-oxide (SrTiO3, LaAlO3, and BaZrO3) buffer-layer films grown on single-crystal oxide substrates by solution deposition. The authors used a metal-organic deposition technique using metal alkoxides as the starting precursor materials. The resulting films were extremely smooth and fully dense, and the quality of the films also was examined by depositing YBCO films on them using a pulsed- laser-deposition (PLD) technique. A 0.3 micrometer YBCO film deposited on a LaAlO3 film, which had been grown at 800^oC on a single-crystal SrTiO3 substrate, was epitaxial and had a zero-resistance Tc of 90.4 K and a 77 K self-field Jc of 2.2 x 10^6 A/cm^2. The authors report, however, that further optimization of the deposition and growth conditions will be needed to obtain films of this quality on deformation-textured metal substrates.
RBa2Cu3O7-d
As reported by A. Crisan (Southampton and Bucharest) et al., the resistive transitions R(T) and current-voltage (I-V) characteristics in the range 10^[-9] - 10^[-6] V and close to Tc have been measured using a SQUID picovoltmeter in a single grain of melt-textured YBCO and in a detwinned YBCO single crystal with the current parallel to the ab-planes and in zero applied magnetic field. For T < Tc, the authors could interpret the lower part of the I-V curves in the framework of the H. J. Jensen and P. Minnhagen [Phys. Rev. Lett. 66, 1630 (1991)] model of current-induced unbinding of thermally created vortex-antivortex pairs, which leads to V proportional to I(I-I_[c1])^[a-1]. The results also confirm a recently proposed current-temperature (I-T) phase diagram of S. W. Pierson [Phys. Rev. B 55, 14536 (1997)].
A study of the effect of KClO3 and K2CO3 additives upon the transition temperature Tc, ac susceptibility, and microstructure of YBCO ceramic superconductors is reported by A. Veneva (Sofia) et al. The authors found that Tc was higher in all KClO3-doped samples than in both K2CO3- doped and undoped YBa2Cu3O7-d. Measurements of the magnetic susceptibility of KClO3-doped YBa1.8K0.2Cu3O7-d showed an onset Tc = 105 K.
Enhancements of interface pinning and aging of the critical currents in NdBa2Cu3O7-d/Nd4Ba2Cu2O10 (Nd-123/Nd-422) melt-textured ceramic composites have been observed by T. Puig (Barcelona) et al. upon high- oxygen-pressure annealing (up to 180 bar). The authors found that Nd- 123/Nd-422 interfaces become the dominant flux-pinning centers when the high-oxygen-pressure treatments are properly chosen, resulting in strongly enhanced critical currents at low and intermediate magnetic fields.
The influence of a high oxygen partial pressure during directional solidification of melt-processed YBa2Cu3O7-d intended for use in current leads has been studied by Y. Imagawa et al. (SRL-ISTEC). The authors found that high oxygen partial pressure (at 1 bar) permits the growth speed to be increased without degradation of the superconducting properties. A sample grown at 5 mm/h in a 100% O2 atmosphere had as high a Jc (6.8 x 10^4 A/cm^2) as a sample grown at 3 mm/h in air.
The growth of large YBa2Cu3O7-d (Y-123) monodomains with diameters up to 7 cm is reported by P. Gautier-Picard et al. (Grenoble). Top-seeded melt texturing (TSMT) was employed, usually with a SmBa2Cu3O7-d seed. The authors discuss the conditions for achieving large domain diameters without producing too high a level of Y2BaCuO5 (Y-211).
Bi Cuprates
Using high-energy x-ray diffraction with 100 keV photons from a synchrotron source, T. Frello (Riso) et al. have monitored the concentration, stoichiometry, and texture of the dominant phases in a Ag-clad BiSCCO tape in-situ during the transformation of BiSCCO from (Bi,Pb)2Sr2CaCu2O8+d (2212) to (Bi,Pb)2Sr2Ca2Cu3O10+d (2223). In addition, the authors obtained information about the grain sizes and residual strains. During heating, the (Ca,Sr)2PbO4 additive decomposes between 700^oC and 820^oC. Simultaneously, the residual strain in the 2212 grains is relieved, and the c-axis alignment of the grains is substantially improved. Moreover, the Pb content of the 2212 structure increases continuously. The authors interpret these results in terms of a temperature-dependent solubility limit of Pb in 2212, which leads to a substantial grain growth of the phase. Above 812^oC, 2212 partly decomposes to form (Ca,Sr)2CuO3 and a liquid. At the operating temperature of 835^oC, 2212 and (Ca,Sr)2CuO3 react with the liquid to form 2223. During the conversion, the 2212 lattice expands, indicating that the remaining 2212 grains contain less and less Pb. The final 2212 and 2223 textures are nearly identical, and Avrami plots of the transformation kinetics give exponents m in the range 1 < m < 2. During the annealing, the 2212 linewidth is constant, indicating that there is neither strain nor finite-size broadening of the 2212 peaks during the transformation. This points to a transformation mechanism where only a few 2212 grains transform at a given time. The authors discuss the implications of their findings in relation to previously proposed intercalation and nucleation-and-growth models.
As noted by P. Skov-Hansen (Nordic Superconductor Technologies) et al., high-temperature-superconducting (HTS) tapes are now commercially available for practical applications such as magnets and cables, but the published data on strength and allowable deformation limits are not in agreement. The authors discuss definitions and concepts regarding stresses and strains in HTS under deformations, and they present criteria for industrial use. When handling HTS tapes, it is necessary to know the limiting values of loading, bending, and twisting to avoid damage, quantified as degradation of current-carrying capability. Most serious is crack formation, which takes place when stress concentrations exceed a certain value. Values of 0.2-0.5% total tensile strain in the ceramic core is quoted as the deformation limit where cracks appear in HTS tapes.
A method to continuously combine and deform silver-clad superconducting strands has been developed by K. DeMoranville et al. (American Superconductor Corporation). The authors used this technique to fabricate multifilamentary superconducting tapes consisting of Bi-2223 precursors in lengths approaching 100 m. Engineering critical current densities as high as 19 kA/cm^2 (77 K, self-field, 1 microvolt/cm) have been recorded in short samples.
A preprint by T. G. Holesinger (Los Alamos) et al. reports examinations of high critical current density (Jc) (Bi,Pb)2Sr2Ca2Cu3O10+d (Bi-2223) multifilamentary tapes (55 kA/cm^2 < Jc < 70 kA/cm^2, 77 K and self- field) by transmission electron microscopy (TEM). Filament microstructures within the tapes consist of two distinct regions: a highly aligned, dense colony structure (brick-wall) near the silver interface and a porous, poorly textured interior region (impurity channel), which contains significantly more secondary phases.
Enhancements of the transport critical current density in Bi-2223 tapes by fission tracks are reported by G. W. Schulz (Atominstitut-Wien) et al. The authors processed Bi2Sr2Ca2Cu3O10+d (Bi-2223) tapes by the standard powder-in-tube technique, but they added small amounts of UO4 prior to processing. Both U-doped and U-undoped tapes were subsequently exposed to a reactor spectrum of neutrons. Whereas the U-undoped materials showed moderate enhancements of the critical current density Jc due to the pinning action of the fast-neutron-induced collision cascades, Jc in the U-doped tapes increased by factors of 10-20 due to thermal-neutron-induced fission of [235]^U and the subsequent formation of fission tracks. Since the enhancements due to columnar defects are particularly pronounced when the magnetic field is applied perpendicular to the tape surface, the characteristic Jc anisotropy as a function of the angle of the field relative to the ab-planes was found to be strongly reduced in a certain field range. At the same time, the irreversibility field at 77 K doubled for both field orientations.
The ab-plane infrared spectrum of underdoped Bi2Sr2Ca1-xYxCu2O8+d has been studied by N. L. Wang (Simon Fraser) et al. as a function of temperature. The authors found the gaplike suppression in scattering rate 1/tau(omega) observed above and below Tc to be related to the shoulder structure in reflectivity R(omega) and the broad peak or downward suppression from Drude-like shape in conductivity sigma_1(omega). The authors conclude that the superconducting gap, which is visible in sigma_1(omega), evolves smoothly into the pseudogap. The results obtained are consistent with recent electron tunneling and photoemission measurements.
Hg Cuprates
The synthesis, phase stability, and superconducting properties of Re- doped HgBa2CaCu2O6+d (Hg-1212) and HgBa2Ca2Cu3O8+d (Hg-1223) are reported by P.V.P.S.S. Sastry and J. Schwartz (Florida State). The authors found that Hg0.8Re0.2Ba2CaCu2O6+d [(Hg,Re)-1212] (Tc = 124 K) had larger, aligned colonies of grains, while Hg0.8Re0.2Ba2Ca2Cu3O8+d [(Hg,Re)-1223] (Tc = 134 K) had smaller, randomly oriented grains. Both microstructure and magnetization hysteresis measurements suggest that (Hg,Re)-1212 is a better candidate for applications.
A preprint by Y. Li (Florida State) et al. describes the synthesis and processing parameters that affect the phase purity and grain growth of Pb-doped Hg-1223. As-synthesized (Hg,Pb)-1223 samples were found to be optimally doped and to exhibit Tc values in the range 130-134 K. Post- annealing the samples in flowing oxygen or argon at 250-300^oC resulted in degraded Tc and reduced magnetic hysteresis.
Second peaks were found by S. Lee (Tokyo Tech and Moscow State) et al. in the magnetization hysteresis loops of (Hg,Pb)(Sr,Ba)2Ca2Cu3O8+d [(Hg,Pb)-1223] polycrystalline bulks and single crystals. The authors also studied the influence of post-annealing on the peak position H_[sp]. The authors found that the H_[sp] vs T curves for Sr-rich (Hg,Pb)-1223 are at higher fields than those that have been reported for conventional Hg-1223 and Tl-1223 single crystals, which suggests that the Sr-rich (Hg,Pb)-1223 compounds have reduced lattice parameters and electronic anisotropy. At 77 K, Jc values of 3 x 10^5, 2.8 x 10^4, and 1.8 x 10^4 A/cm^2 were estimated for the single-crystal sample at H = 0, 1, and 2 T, respectively. The authors suggest that (Hg,Pb)(Sr,Ba)2Ca2Cu3O8+d is a promising candidate for high-current applications.
La2-xSrxCuO4
Recent neutron-scattering experiments on La2-xSrxCuO4 single crystals by Wakimoto et al. have revealed that elastic magnetic peaks appear at low temperatures in both insulating (x = 0.02-0.05) and superconducting (x = 0.06) samples. A new preprint by S. Wakimoto (Tohoku) et al. reports further investigations of the elastic incommensurate peaks for x = 0.06. The authors found that the integrated intensity drastically changes across the low-temperature insulator-superconductor boundary; the intensity for x = 0.06 is one-fourth that of x = 0.05, while the intensity in the insulating region is constant.
Neutron-scattering experiments have been performed by H. Kimura (Tohoku) et al. to search for possible elastic incommensurate magnetic peaks in superconducting La2-xSrxCuO4 with x = 0.10, 0.12, and 0.15. Dramatic effects were found for x = 0.12, where the peak intensity first appears at the onset of superconductivity (Tc = 31 K). The resolution-limited peak width indicates that the static magnetic correlation length exceeds 200 Angstroms isotropically in the CuO2 planes. Weak elastic peaks also were observed at low temperatures for x = 0.10, while for x = 0.15 any incommensurate elastic scattering is below the limit of detectability. Elastic peaks also were observed in Zn-substituted nonsuperconducting La1.88Sr0.12Cu0.97Zn0.03O4. However, in this case, the Zn substitution degrades the magnetic order; the peak appears at lower temperature (17 K), and the correlation length (80 Angstroms) is shorter than that in the Zn-free x = 0.12 sample.
A preprint by R. J. Birgeneau (MIT) et al. describes a neutron- scattering study of the instantaneous spin-spin correlations in La2CuO4 (T_N = 325 K) over the temperature range 337-824 K. Incident neutron energies varying from 14.7 meV to 115 meV were employed to guarantee that the energy integration was carried out properly. The results obtained for the spin correlation length as a function of temperature agree quantitatively with previous results for the two-dimensional tetragonal material Sr2CuO2Cl2 and with quantum Monte Carlo results for the nearest-neighbor square-lattice S = 1/2 Heisenberg model.
Vortices
Magnetic-flux turbulence has been observed via magneto-optical imaging by T. Frello (Oslo and Riso) et al. in single crystals of NdBa2Cu3O6+x near optimal doping (x ~~ 1) and underdoped YBa2Cu3O6+x (x = 0.50, 0.82). Such turbulent behavior had previously been reported only for high-quality YBa2Cu3O6+x single crystals with optimal doping. The authors discuss the influence of the critical current density Jc, anisotropy gamma, and oxygen content and superstructure upon the turbulent behavior. The authors conclude that turbulence in states containing magnetic flux of opposite polarities is a general phenomenon.
Vortex flow across a strip containing an array of pinning centers has been studied by K. E. Bassler (Houston) et al. using a cellular model. The vortex flow makes rivers that are strikingly similar to aerial photographs of braided fluvial rivers, such as the Brahmaputra. The vortex rivers form an intricate braided pattern with interconnected channels. The authors find agreement between the scaling properties of the braided vortex rivers and those of naturally occurring braided fluvial rivers. The authors argue that in both cases the underlying dynamical mechanism is avalanches of stick-slip events, either sliding sediment or vortices, which organize the system into a critical braided state.
To determine the effect of sample shape on the magnetization of Bi2Sr2CaCu2O8+d (Bi-2212) single crystals, R. A. Doyle (IRC-Cambridge) et al. have measured the magnetic moments of differently shaped crystals using a SQUID magnetometer. In platelet-shaped samples, the results show a pronounced geometrical barrier (GB) or shape effect at low fields and high temperatures. In both prism and semi-ellipsoidal-shaped samples, the low-field magnetic hysteresis is reduced significantly at high temperatures due to modification of the geometrical barrier. At lower temperatures, the prism and semi-ellipsoidal samples show enhanced low-field hysteresis relative to the platelet, suggesting an increasing role of nongeometrical surface barriers (SB). The authors discuss these results in terms of the competing roles of bulk-pinning, surface- barrier, and geometrical-barrier effects.
Results of numerical calculations are presented by T. B. Doyle (Natal) et al. for the field-distribution profiles in a reversible (bulk- pinning-free) type-II superconductor of disk geometry in the vortex- lattice-melting regime. The authors assume the melting transition is a first-order transition between solid and liquid states, which have different constitutive equilibrium B(H) behaviors. The authors simulate an intermediate-state structure of varying scales by imposing hysteresis on the melting transition H_m(T). Particular calculations ranging from a fine-scale to an extremely coarse-scale two-zone intermediate-state limit, which previously has been assumed for the transition, are presented for comparison with global magnetization and local surface induction measurements on Bi-2212 single crystals in the vortex-melting regime. The authors discuss their results in relation to the determination of the entropy of the melting transition from such measurements and to the nature and curvature of the solid-liquid interface.
A preprint by A. V. Kuznetsov (Moscow State) et al. theoretically considers (a) vortex penetration into thin superconducting films and (b) edge barriers arising in a transverse magnetic field. The authors calculate the vortex Gibbs energy using V. G. Kogan's solution [Phys. Rev. B 49, 15874 (1994)] for a Pearl vortex near the film edge. The authors calculate the penetration field and the magnetization in the critical state, and they estimate the influence of the edge barrier on the magnetization of high-Tc thin films.
Using torque magnetometry, A. V. Pan (Leipzig) et al. have investigated the transverse magnetization in niobium films of thickness 120 nm and 1.2 micrometers at different angles theta between the applied field and the main surface of the films. Torque measurements at angles 2 degrees <= theta <= 10 degrees in the 120 nm film reveal nearly temperature- independent anomalies in the magnetization at matching fields that are compatible with the rearrangement of vortices in one or two in-plane rows, while in the 1.2 micrometers film these anomalies are not observed. Surprisingly, at very small angles (theta < 0.5 degree), the matching effects vanish. At these small angles and for both films, the observed behavior can be understood if vortices due to the perpendicular field component experience a pinning barrier of geometrical origin for flux entry or exit. The authors also suggest that the results in both Nb films indicate the simultaneous presence of two flux-line lattices, one parallel and one perpendicular to the main surface of the film.
Vibrating-reed, torque, and SQUID measurements have been performed by P. Esquinazi et al. (Leipzig) on Nb networks of strand widths between 200 nm and 550 nm and on Nb films of thickness 120 nm and 1.2 micrometers. The results indicate that in samples with thickness ~10 xi_[GL] a flux- line lattice exists in the entire field range B_[c1] <= B_a <= B_[cu], where B_[cu](T,theta=0 degree) = B_[c3](T), the surface superconductivity critical field, B_[cu](T,theta=90 degrees) = B_[c2](T), the upper critical field, and theta is the angle between the field and the main surface. Magnetization measurements revealed a second magnetization peak (SMP) well below the upper critical field, similar to that measured in Bi2Sr2CaCu2O8+d (Bi-2212) crystals. The authors argue that the SMPs measured in Nb and Bi-2212 are due to a thermomagnetic flux-jump instability and are not related to a critical- current-density enhancement produced by a flux-line-lattice phase transition in an increasing magnetic field.
ac Losses
Measurements of the ac losses in several high-temperature superconductor (HTS) prototype multistrand conductors (PMCs) of length 1 m have been performed by J. O. Willis (Los Alamos) et al. using a temperature- difference calorimeter. Both single-phase and three-phase losses were examined with ac currents up to 1000 A rms in the PMC. The three-phase losses indicate a significant interaction between phases and show a smaller dependence on the tape I_c than expected.
Electrical measurements of the dc current distribution and self-field ac losses of three HTS cable models are reported by C. M. Friend et al. (BICC Superconductors). Each cable consisted of one or two layers of spirally wound Bi-2223 tape. Nonuniform distributions of the current were found, which could be attributed to variations in terminal resistances and tape degradation during winding. The authors discuss three different configurations for the voltage leads and the disadvantages of each.
A paper by F. Goemoery et al. (Pirelli) demonstrates how the hysteretic transport ac losses in multifilamentary superconducting tapes can be determined in a contactless way using a pickup coil attached to the tape's wide face. The assumption of uniformly distributed current density gives results that are correct to within 25%. Since the coil signal is directly proportional to the number of turns, the method provides increased sensitivity compared with voltage contacts, which can be helpful when investigating tapes with extremely low ac losses.
As noted in a paper by V. Sokolovsky and V. Meerovich (Ben-Gurion University of the Negev), because of the low thermal conductivity of high-temperature-superconducting materials, ac losses can lead to pronounced heating of the interior parts of a bulk sample. The authors show that the heating increases (decreases) the losses in magnetic fields below (above) the complete penetration field. The authors note that calculations of the ac losses neglecting heating can have large errors.
The low-frequency surface impedance of melt-textured superconductors has been studied theoretically and experimentally by L. M. Fisher (Moscow) et al. The authors use a model assuming that the main pinning of the vortex system is due to intercrystalline boundaries.
Microwave Response
Nonlinear microwave emission by Ba0.6K0.4BiO3 crystals has been studied by A. Agliolo Gallitto et al. (Palermo). The authors suggest that harmonic emission at temperatures far from Tc is due to nonlinear processes in weak links or flux motion, but they attribute nonlinearity near Tc to time variation of the order parameter induced by the microwave field.
The microwave surface impedance of a high-purity crystal of YBa2Cu3O6.99 has been measured by A. Hosseini et al. (UBC) at five frequencies between 1 and 75 GHz. The data reveal the main features of the conductivity spectrum of the thermally excited quasiparticles in the superconducting state. Below 20 K, there is a regime of extremely long quasiparticle lifetimes, due to both the collapse of inelastic scattering below Tc and the very weak impurity scattering in the high- purity BaZrO3-grown crystal used in this study. Above 20 K, the scattering increases dramatically, initially at least as fast as T^4.
A quantitative study of the effect of a-axis grains (for which the a axis is perpendicular to the substrate plane) on the microwave surface resistance in epitaxial YBa2Cu3O7-d films is reported by C. Dubourdieu (St. Martin d'Heres) et al. The films were grown by metal organic chemical vapor deposition (MOCVD) on MgO and LaAlO3 substrates. The authors found a clear correlation between the 87 GHz surface resistance R_s at 0.85 Tc and the volume fraction of a-axis grains. The authors argue that this is a direct consequence of the penetration-depth anisotropy.
The propagation of microwaves along YBa2Cu3O7-d microstrip lines of different widths has been modeled by M. S. Boutboul et al. (Paris). The authors used the two-fluid model to calculate the surface impedance R_s + jX_s and the propagation constant alpha + j[beta], accounting for losses in the dielectric and the metallic ground plane. The authors applied the model to analyze experimental results on a 5.3 GHz cutoff frequency low-pass filter, consisting of YBa2Cu3O7-d microstrip lines of widths 190 micrometers and 2000 micrometers deposited on a LaAlO3 substrate.
Thin Films
The microstructure of interface-engineered ramp-edge Josephson junctions in YBCO has been studied by Y. Huang (Argonne) et al. using transmission electron microscopy (TEM). The junctions are found to be distinctly different from those found in heterophase SNS junctions, and the structural difference can be related directly to the improved electrical properties of interface-engineered junctions. The main factors responsible for the improved junction properties and their good reproducibility are: small barrier thickness, small thickness variation, weak interfacial strain fields, flat and nearly defect-free barrier/YBCO interfaces, and good epitaxy of the second YBCO layer with few defects.
Measurements of the resistive broadening and the critical current density of an epitaxial YBa2Cu3O7-d film are reported by Z. H. Wang (Shanghai) et al. at several fixed magnetic fields as a function of the angle between the applied field and the surface of the film. The authors attribute the pinning to intrinsic pinning for fields parallel to the ab-planes, and to twin planes and 2D defects along the c axis for fields parallel to the c axis.
The conditions required for the deposition of nonsuperconducting, cubic (Y0.33Ba0.67)CuOx by high-speed pulsed-laser deposition (PLD) have been investigated by J. D. Suh (Taejon) et al. Recently, cubic YBCO has attracted attention because it has essentially the same perovskite crystal structure and stoichiometry as those of orthorhombic YBa2Cu3O7-d and thus has promise as a barrier layer in SNS edge-type Josephson junctions. The authors found that cubic YBCO thin-film growth could be produced by PLD at high deposition rates of 12.2 nm/s.
High-temperature-superconducting/ferroelectric thin-film devices are of interest because of their possible application in voltage-tunable devices. Two preprints listed in this issue discuss research on this topic. R. A. Chakalov et al. (Chalmers University of Technology) report on the fabrication and investigation of YBa2Cu3O7-d/Ba0.05Sr0.95TiO3 structures, including a coplanar waveguide, which was tested as an electrically tunable phase-shifter. Field-induced phase shifts of more than 180 degrees were obtained by a 35 V dc bias at 20 GHz. D. Mou et al. (Royal Institute of Technology) report on the electrical properties of heterostructures of YBa2Cu3O7-d/PbTiO3. Schottky and Frenkel-Poole effects were found to dominate the leakage current of the heterostructure.
Applications
A hybrid bilayer device, a controllable Josephson junction consisting of a thin, microstructured ferromagnetic film spanning a superconducting strip, is described in a preprint by T. W. Clinton and M. Johnson (NRL). Locally strong magnetic fringe fields at the edge of the ferromagnet quench the superconductivity, creating a weak link. The strength of the weak link can be varied between on and off by controlling the orientation of the in-plane magnetization of the ferromagnet. The authors observed Shapiro steps, a manifestation of the ac Josephson effect in the quenched state. In this switchable device, energy is required only to change states, which thereafter remain in metastable equilibrium. The effect has been demonstrated in Pb (Tc = 7.2 K), but it also should occur with many other superconductors. The authors note that the switch could be used as an intrinsic nonvolatile memory cell, a pressing need in superconducting electronics, but they suggest that applications as a high-speed switch, amplifier, and controllable weak link also are possible.
The fabrication of PLD Ag-doped YBCO thin films on both sides of three- inch-diameter sapphire wafers is described in a preprint by M. Lorenz (Leipzig) et al. Such films are under development as microwave filters for future communication systems. The authors report that reproducibly deposited YBCO:Ag films of about 250 nm thickness show critical current densities of 4 MA/cm^2 at 77 K and exhibit laterally homogeneous maps of microwave surface resistance R_s of about 45 milliohms at 145 GHz and 77 K measured by an open resonator technique. The R_s at 8.4 GHz and 77 K determined in the center position of the YBCO:Ag films with a sapphire resonator technique remains constant at about 380 micro-ohms up to a microwave surface magnetic field of 7-10 mT.
As reported by G. Snitchler (American Superconductor Corporation) et al., a 7.25 T laboratory magnet using Bi-2223 conductor has been designed, built, installed, and tested at the Naval Research Laboratory. Operating at 21 K at full field, the coil provides field homogeneity of +-1% in a 2-inch warm bore. The system is conduction-cooled with a pair of Leybold single-stage cryocoolers, which allow cooldown in less than 36 hours and permit extended fast-ramp operation. Operation at a total refrigerator input power of 6 kW is facilitated by the use of ASC Cryosaver[TM] HTS current leads. The fully integrated system consists of the magnet, cryogenic system, control and protection system, and power supply.
In particle accelerators and other high-energy physics applications, over one-third of the liquid-helium consumption results from the use of conventional resistive cryogenic current-lead technology. As noted by A. J. Rodenbush et al. (American Superconductor Corporation), these and other applications can benefit greatly by incorporating high- temperature-superconducting leads. These leads consist of a vapor- cooled resistive upper section and an HTS section cooled by a separate gas stream. This topology reduces the helium consumption to one-tenth of that required by a resistive lead. The authors describe the design, fabrication, and testing of several HTS current leads including 5 kA and 13 kA leads for accelerators.
The performance of a small saddle coil for quadrupole magnets made in industry from Bi-2223 HTS tape at 4.2 K and 77 K is reported by M. D. Manlief (American Superconductor Corporation) et al. The coil was made to help develop methods for winding the ends of small-aperture magnets.
The United States Air Force and the Ballistic Missile Defense Organization are developing a 1-Megawatt exciter/generator for airborne applications. The exciter is constructed with an eight-pole external field winding and rotating hydrogen-cooled armature with integral rectifier. The exciter was originally designed with high-purity aluminum field coils cooled by liquid hydrogen. The Air Force is presently investigating the possibility of replacing the aluminum field coils with HTS field coils cooled by hydrogen. A. J. Rodenbush and S. J. Young (American Superconductor Corporation) describe the design, construction, and testing of the field coils, and they discuss the potential of this technology for airborne applications.
The status of a 1,000 hp synchronous motor with HTS field windings is summarized in a preprint by D. Aized (American Superconductor Corporation) et al. The objectives of this development effort include saving half the losses of conventional motors in a package with half the volume. The authors review the overall design characteristics of the motor, discuss the status of the field coils and refrigeration system, and describe the other components of the system. Present schedules call for the motor to be tested in mid-1999.
A paper by S. K. Singh (Westinghouse Science & Technology Center) et al. describes the conceptual design of the HTS generator for mobile radar (MR) applications. The power system for MR consists of a diesel engine, a generator, and power conditioning electronics. Significant advantages in power density, performance, and efficiency are expected if the generator and power electronics are cryogenically cooled.
Theory
Order-parameter fluctuation effects in the superconducting state have been studied by H.-J. Kwon (Florida) as a possible explanation of the pseudogap. Using a low-energy effective theory in the d-wave BCS model, the author self-consistently calculates the single-particle properties and finds that the fluctuations reduce the spectral gap, deform the shape of the gap, and produce a precursor to the formation of Fermi arcs. The author also discusses the angle dependence of the quasiparticle lifetime due to fluctuations.
Time-reversal-symmetry-breaking superconductivity with Delta_[k] = Delta_[x^^2-y^^2](k)+e^[itheta]Delta_[alpha] (alpha = s or d_[xy]) symmetries has been studied by H. Ghosh (Rio). The author shows that, depending on the minor component (alpha) and its phase at lower temperatures, the behavior of such superconductors could be qualitatively different, which can have important consequences for transport and Josephson physics.
To investigate relations among long-range antiferromagnetic (AF) order, superconductivity, and two-particle triplet collective excitations, D. Marinaro and O. Sushkov (New South Wales) have considered a modified two-dimensional t-J model at doping close to half filling. The model includes additional hopping t" and nearest-site Coulomb repulsion V, allowing the authors to control closeness of the system to the AF instability. The authors demonstrate the possibility of coexistence of long-range AF order and d-g-wave superconductivity. In the phase with long-range AF order, the authors find superconducting gaps and spin-wave renormalization. Near the AF instability, the authors find a spin- triplet collective excitation with energy below the superconducting gap.
A preprint by S. Fratini and P. Quemerais (Grenoble) describes an examination of the stability of a Wigner crystal in an ionic dielectric, in which the authors found two important competing effects due to polaron formation: (a) the screening of the Coulomb force 1/eplison_sr, which destabilizes the crystal, compensated by (b) the increase of the carrier (polaron) mass. The authors study the competition between the two effects and examine the quantum melting of the polaronic Wigner crystal as the density is varied at zero temperature. By calculating the quantum fluctuations of both the electron and the polarization, the authors show that there is a competition between dissociation of the polarons at the insulator-to-metal transition (IMT) and melting towards a polaron liquid. The authors find that at strong coupling, a liquid state of dielectric polarons cannot exist, and the IMT is driven by the polaron dissociation.
The cooperative Kondo effect in the two-channel Kondo lattice has been studied by P. Coleman (Rutgers) et al. The authors find that additional screening channels destabilize the Fermi liquid, ultimately leading to a superconducting state with long-range composite order. The authors discuss possible implications for heavy-fermion superconductivity.
Overviews
The fundamentals governing the penetration of magnetic flux into the high-temperature superconductors are discussed in an overview by J. R. Clem (Ames Lab-Iowa State). The author discusses (a) the internal magnetic structure when magnetic flux penetrates into a superconductor (anisotropic, pancake, and Josephson vortices) and (b) the process by which vortices nucleate at the edge and penetrate to the sample's interior (geometric and surface barriers) (101 refs.).
A preprint by A. Furusaki (Kyoto and Stanford) reviews the dc Josephson effect in superconducting point contacts, where supercurrent flows through a small number of channels. The author emphasizes the central role of Andreev levels, which carry the entire supercurrent in short symmetric Josephson junctions, including tunnel junctions. The author also explains the dc Josephson effect in a quantum point contact in terms of multiple Andreev reflections, and points out that the Josephson critical current is quantized in multiples of eDelta_0/h[bar] at zero temperature (39 refs.).
The status of and prospects for high-temperature-superconducting (HTS) Bi-2223 oxide-powder-in-tube (OPIT) wire technology in the context of commercial requirements, as well as alternative wire approaches such as YBCO coated conductors, are summarized in a paper by A. P. Malozemoff et al. (American Superconductor Corporation). The author reports that short rolled multifilamentary Bi-2223 OPIT wire has reached a core critical current density Jc over 73,000 A/cm^2 (77 K, self-field, 1 microvolt/cm) in multiple samples, with engineering (full-cross-section) current density J_e of 22,800 A/cm^2. Regular production wires several hundred meters long show average engineering current density over 10,000 A/cm^2, a benchmark for commercial electric power applications such as cables and motors. Cost studies indicate that cost performance below $10/kA-m is attainable for full-scale production levels. The author notes that next-generation YBCO coated-conductor technology offers further potential cost-performance improvements (16 refs.).
Contributed by John R. Clem
Contents: Preprints begin on page 8 adn Coming Events are 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.
D. Aized, B. B. Gamble, A. Sidi-Yekhlef, J. P. Voccio, D. I. Driscoll, B. A. Shoykhet, and B. X. Zhang, "Status of the 1,000 hp HTS Motor Development." Presented at the 1998 Appl. Supercond. Conf. (ASC), Palm Desert, Calif., Sept. 13-18, 1998. American Superconductor Corporation, Two Technology Drive, Westborough, MA 01581-1727; telephone (508) 836- 4200; telefax (508) 836-4248; e-mail jcrail@amsuper.com.
Shunichi Arisawa, Takeshi Hatano, Keikichi Nakamura, and Kazumasa Togano, "Effect of the Substrates of In-Situ Fabrication of Borocarbide Thin Films." To be published in Physica C (in press). National Research Institute for Metals, 1-2-1 Sengen, Tsukuba-shi, Ibaraki 305 0047, JAPAN; telephone +81 298 59 2320; telefax +81 298 59 2301; e-mail arisawa@nrim.go.jp. Key words: borocarbide, superconductor, thin film. 74.72.Yg.
S. S. Banerjee, S. Saha, N. G. Patil, S. Ramakrishnan, A. K. Grover, S. Bhattacharya, G. Ravikumar, P. K. Mishra, T.V.C. Rao, V. C. Sahni, C. V. Tomy, G. Balakrishnan, D. Mck. Paul, and M. J. Higgins, "Generic Phase Diagram for Vortex Matter via a Study of Peak Effect Phenomenon in Crystals of 2H-NbSe2." To be published in Physica C (in press). Contact A. K. Grover, Department of Condensed Matter Physics and Materials Science, Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400005, INDIA; e-mail grover@tifr.tifr.res.in. Key words: type-II superconductors, vortex state, generic magnetic phase diagram, peak effect, thermomagnetic history dependence.
*Victor Barzykin and Alexandre M. Zagoskin, "Coherent Transport and Nonlocality in Mesoscopic SNS Junctions: Anomalous Magnetic Interference Patterns." Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, BC, CANADA V6T 1Z1; Alexandre M. Zagoskin's e-mail zagoskin@physics.ubc.ca; preprint also available at cond-mat@xxx.lanl.gov (#9805104). *Revised.
K. E. Bassler, M. Paczuski, and G. F. Reiter, "Braided Rivers and Superconducting Vortex Avalanches." Preprint #98:102; submitted to Nature. 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.
R. J. Birgeneau, M. Greven, M. A. Kastner, Y. S. Lee, B. O. Wells, Y. Endoh, K. Yamada, and G. Shirane, "Instantaneous Spin Correlations in La2CuO4." Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139; telephone (617) 253-8900. 75.10.Jm; 75.50.Ee; 75.40.Cx; 64.60.Kw.
M. S. Boutboul, H. Kokabi, and M. Pyee, "Modeling of Microstrip Quasi- TEM Superconducting Transmission Lines, Comparison with Experimental Results." To be published in Physica C (in press). Contact H. Kokabi, Laboratoire LDIM, Tour 12, 2 eme etage, Universite Pierre et Marie Curie 4, Place Jussieu, F-75252 Paris Cedex 05, FRANCE; telephone +33 1 4427 4371; telefax +33 1 4427 4382; e-mail kokabi@moka.ccr.jussieu.fr. Key words: YBaCuO, microstrip, quasi-TEM approach.
R. A. Chakalov, Z. G. Ivanov, Yu. A. Boikov, P. Larsson, E. Carlsson, S. Gevorgian, and T. Claeson, "Fabrication and Investigation of YBa2Cu3O7- d/Ba0.05Sr0.95TiO3 Thin Film Structures for Voltage Tunable Devices." To be published in Physica C (in press). Department of Physics, Chalmers University of Technology, S-41296 Goeteborg, SWEDEN; telephone +46 31 772 3286; telefax +46 31 772 3471; e-mail radoslav@fy.chalmers.se. Key words: thin film, laser ablation, voltage tunable devices.
G. Chiodelli, I. Wenneker, P. Ghigna, G. Spinolo, G. Flor, M. Ferretti, and E. Magnone, "Oxygen Non-Stoichiometry and High Temperature dc Conductivity of SmBa2Cu3O6+x." To be published in Physica C (in press). Contact P. Ghigna, I.N.C.M., Dip. Chimica Fisica, and C.S.T.E./C.N.R., Universita di Pavia, Viale Taramelli 16, I-27100 Pavia, ITALY; telephone +39 382 507 574; telefax +39 382 507 575; e-mail paolo@chifis.unipv.it. Key words: SmBa2Cu3O6+x, 123 superconductors, large polarons.
John R. Clem, "Magnetic Flux Penetration into the High-Temperature Superconductors." To be published in Phys. and Mater. Sci. of Vortex States, Flux Pinning, and Dynamics: Proc. of the NATO Adv. Study Inst., Kusadasi, Turkey, July 26-Aug. 8, 1998, edited by S. Bose and R. Kossowski (Kluwer, 1999). A517 Physics, Ames Laboratory-USDOE and Department of Physics, Iowa State University, Ames, IA 50011-3020; telefax (515) 294-0689; e-mail clem@ameslab.gov.
T. W. Clinton and Mark Johnson, "Nonvolatile Switchable Josephson Junctions." To be published in J. Appl. Phys. Code 6341, Materials Physics Branch, Naval Research Laboratory, 4555 Overlook Ave. S.W., Washington, DC 20375-5320.
P. Coleman, A. M. Tsvelik, N. Andrei, and H. Y. Kee, "Co-Operative Kondo Effect in the Two-Channel Kondo Lattice." Serin Physics Laboratory, Rutgers University, P. O. Box 849, Piscataway, NJ 08855-0849; e-mail coleman@pion.rutgers.edu; preprint also available at cond- mat@xxx.lanl.gov (#9811006). 78.20.Ls; 72.15.Gd.
A. Crisan, S. N. Gordeev, S. Manton, A. P. Rassau, S. Popa, C. Beduz, P.A.J. de Groot, R. Gagnon, and L. Taillefer, "Investigations of the Zero-Field (a,b)-Plane Conductivity of YBa2Cu3O7-d Near the Critical Temperature." To be published in Physica C (in press). Dipartimento di Scienze e Tecnologie Fisiche ed Energetiche, INFM-Universita di Roma "Tor Vergata", Via di Tor Vergata, I-00133 Roma, ITALY; telefax +39 6 7259 7145; e-mail ioan@ing.uniroma2.it. Key words: YBCO, critical temperature, current, voltage.
A. N. Das and Biplab Chattopadhyay, "An Extended Pair Tunneling Model: Studies on Bilayer Splitting and Some Superconducting State Properties." To be published in Physica C (in press). Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Calcutta 700 064, INDIA; telephone +91 337 5345 49; telefax +91 33 337 4637; e-mail atin@cmp.saha.ernet.in. Key words: high-temperature cuprate superconductors, interlayer tunneling, pseudogap, photoemission intensity. 74.20.-z; 74.62.-c; 74.62.Dh.
K. DeMoranville, P. Antaya, C. Martin, Q. Li, G. N. Riley, Jr., S. Hancock, M. Simpson, J. Marquardt, and D. Tatelbaum, "Continuous Multistrand Assembly Techniques for Ag Clad Superconducting Wire." Presented at the 1998 Appl. Supercond. Conf. (ASC), Palm Desert, Calif., Sept. 13-18, 1998. American Superconductor Corporation, Two Technology Drive, Westborough, MA 01581-1727; telephone (508) 836-4200; telefax (508) 836-4248; e-mail jcrail@amsuper.com.
R. A. Doyle, W.A.J. Quinton, F. Baudenbacher, and W. Y. Liang, "Field Dependence of Superconducting Properties of YBa2Cu3O7-d Films on Hastelloy Substrates." To be published in Physica C (in press). Interdisciplinary Research Center in Superconductivity, University of Cambridge, Cambridge CB3 0HE, UNITED KINGDOM; telephone +44 1223 337072; telefax +44 1223 337074; e-mail rad1005@hermes.cam.ac.uk. Key words: YBa2Cu3O7-d (YBCO) films, inclined substrate deposition, irreversibility line, flux pinning.
R. A. Doyle, S.F.W.R. Rycroft, C. D. Dewhurst, E. Zeldov, I. Tsabba, S. Reich, T. B. Doyle, T. Tamegai, and S. Ooi, "The Effect of Sample Shape on the Magnetization in Bi2Sr2CaCu2O8+d Crystals." To be published in Physica C (in press). Interdisciplinary Research Centre in Superconductivity, University of Cambridge, West Cambridge Site, Madingley Road, Cambridge CB3 0HE, UNITED KINGDOM; telephone +44 1223 33 7072; telefax +44 1223 33 7074; e-mail rad1005@hermes.cam.ac.uk. Key words: BSCCO, melting, irreversibility line, geometrical barrier, surface barrier, bulk pinning. 74.60.Ec; 74.60.Ge; 74.60.Jg.
T. B. Doyle, R. Labusch, and R. A. Doyle, "On the Intermediate State and the Melting Transition in High-Tc BSCCO Single Crystal Superconductors." To be published in Phys. and Mater. Sci. of Vortex States, Flux Pinning, and Dynamics: Proc. of the NATO Adv. Study Inst., Kusadasi, Turkey, July 26-Aug. 8, 1998, edited by S. Bose and R. Kossowski (Kluwer, 1999). Department of Physics, University of Natal, King George V Avenue, Durban 4001, SOUTH AFRICA; R. A. Doyle's telephone in Cambridge, UK +44 1223 33 7072; telefax +44 1223 33 7074; e-mail rad1005@hermes.cam.ac.uk.
C. Dubourdieu, J. P. Senateur, O. Thomas, F. Weiss, S. Hensen, and G. Mueller, "Correlation Between the Microwave Surface Resistance and the Volumic Fraction of a-Axis Grains in YBa2Cu3O7-x Films." To be published in Physica C (in press). ENSPG, Institute National Polytech de Grenoble, Rue de la Houille Blanche, F-38042 St. Martin d'Heres, FRANCE; telefax +33 4768 26394; e-mail catherine.dubourdieu@inpg.fr. Key words: thin films, surface impedance, microwave absorption, grain boundaries.
P. Esquinazi, R. Hoehne, Y. Kopelevich, A. V. Pan, and M. Ziese, "Mechanical and SQUID Measurements on Nb Thin Films: Learning from a Conventional Low-Temperature Superconductor." To be published in Phys. and Mater. Sci. of Vortex States, Flux Pinning, and Dynamics: Proc. of the NATO Adv. Study Inst., Kusadasi, Turkey, July 26-Aug. 8, 1998, edited by S. Bose and R. Kossowski (Kluwer, 1999). Department of Superconductivity and Magnetism, Universitaet Leipzig, Linnestrasse 5, D-04103 Leipzig, GERMANY; telefax +49 341 9732769; e-mail esquin@physik.uni-leipzig.de.
L. M. Fisher, S. E. Savel'ev, I. F. Voloshin, V. A. Yampol'skii, and D. T. Shaw, "Electromagnetic Properties of Brickwork-Like Structured Hard Superconductors." To be published in Physica C (in press). All-Russian Electrical Engineering Institute, 12 Krasnokazarmennaya Str., 111250 Moscow, RUSSIA; telephone +7 95 361 9226; telefax +7 95 361 9226. Key words: high-Tc superconductors, flux pinning and creep.
S. Fratini and P. Quemerais, "Polaron Crystallization and Melting: Effects of the Long-Range Coulomb Forces." To be published in Int. J. Mod. Phys. B. Laboratoire d'Etudes des Proprietes Electroniques des Solides (LEPES/CNRS), BP166, F-38042 Grenoble Cedex 9, FRANCE; e-mail fratini@lepes.polycnrs-gre.fr; preprint also available at cond- mat@xxx.lanl.gov (#9811055).
T. Frello, M. Baziljevich, T. H. Johansen, N. H. Andersen, Th. Wolf, and M. R. Koblischka, "Flux Turbulence in NbBa2Cu3O6+x and Underdoped YBa2Cu3O6+x Single Crystals." Submitted to Phys. Rev. B. Condensed Matter Physics and Chemistry Department, Riso National Laboratory, DK- 4000 Roskilde, DENMARK; telephone +45 4677 4719; telefax +45 4677 4790; e-mail frello@risoe.dk. 74.60.Ec; 74.60.Ge; 78.20.Ls.
T. Frello, H. F. Poulsen, L. Gottschalck Andersen, N. H. Andersen, M. D. Bentzon, and J. Schmidberger, "An In-Situ Study of the Annealing Behavior of BiSCCO/Ag Tapes." Submitted to Supercond. Sci. & Tech. Contact H. F. Poulsen, Materials Research Department, Riso National Laboratory, DK-4000 Roskilde, DENMARK; telephone +45 4677 5739; telefax +45 4677 5758; e-mail henning.friis.poulsen@risoe.dk. 85.25.Kx; 61.50.Ks; 61.10.Nz.
C. M. Friend, D. M. Spiller, L. Le Lay, S. A. Awan, and T. P. Beales, "Using Electrical Measurements to Determine the Self-Field ac Losses of Cable Models." To be published in Physica C. BICC Superconductors, Oak Road, Wrexham LL13 9XP, UNITED KINGDOM; telephone +44 1978 662612; telefax +44 1978 662464; e-mail cfriend@bicc.co.uk. Key words: ac loss, cable, Bi-2223 tape. 74.72.Hs; 85.25.Kx; 84.70.+p.
Ayumi Fujita, "Numerical Study for Vortex Lattice Transition with Extended Ginzburg-Landau Model." To be published in Physica C (in press). Muon Science Laboratory, RIKEN, The Institute of Physical and Chemical Research, 2-1 Wako, Saitama 351-0198, JAPAN; telephone +81 48 467 9588; telefax +81 48 462 4648; e-mail afujita@postman.riken.go.jp. Key words: extended Ginzburg-Landau model, d-wave superconductor, mixed phase, Langevin equation. 74.20.De; 74.20.Mn; 74.60.Ec.
Akira Furusaki, "Josephson Current Carried by Andreev Levels in Superconducting Quantum Point Contacts." Submitted to Superlatt. and Microstruc. Department of Physics, Stanford University, Stanford, CA 94305-4060; e-mail furusaki@quantum.stanford.edu; preprint also available at cond-mat@xxx.lanl.gov (#9811026).
A. Yu. Galkin, L. Pust, M. Jirsa, P. Nalevka, and M. R. Koblischka, "On the Dynamics of Vortices in BSCCO(2223)/Ag Tape." To be published in Physica C (in press). Institute of Metal Physics, National Academy of Sciences of Ukraine, Yaroslavskaya 29, Apt. 16, 254071 Kiev, UKRAINE; telephone +380 44 416 0932; e-mail vbaryakhtar@gluk.apc.org. Key words: activation energy, lattice vortex melting.
A. Agliolo Gallitto, M. Guccione, and M. Li Vigni, "Harmonic Emission at Microwave Frequencies in Ba0.6K0.4BiO3 Crystals." To be published in Physica C. Contact M. Li Vigni, Istituto Nazionale per la Fisica della Materia, Unita di Palermo and Dipartimento di Scienze Fisiche ed Astronomiche, Via Archirafi 36, I-90123 Palermo, ITALY; telephone +39 91 623 4207; telefax +39 91 616 2461; e-mail livigni@fisica.unipa.it. Key words: high-temperature superconductors, electromagnetic field response, nonlinear effects. 74.25.Nf; 74.20.De; 74.50.+r.
P. Gautier-Picard, E. Beaugnon, X. Chaud, A. Sulpice, and R. Tournier, "Growth of YBaCuO Mono-Domains: Growth Limit and Mono-Domains with a Diameter up to 7 cm." To be published in Physica C (in press). Laboratoire Leon Brillouin, CEA-Saclay, F-91191 Gif sur Yvette Cedex, FRANCE; e-mail gpp@llb.saclay.cea.fr. Key words: synthesis of YBaCuO, single-crystal growth, grain alignment (texturing). 81.10.Fq; 81.30.Fb.
Haranath Ghosh, "Time Reversal Symmetry Breaking Superconductivity." To be published in Phys. Rev. B. Instituto de Fisica, Universidade Federal Fluminense, Campus da Praia Vermelha, Av. Litoranea s/n, 24210-340 Niteroi, Rio de Janeiro, BRAZIL; e-mail hng@if.uff.br; preprint also available at cond-mat@xxx.lanl.gov (#9810281). 74.72.-h; 74.25.Dw; 74.62.-c.
F. Goemoery, D. Bettinelli, L. Gherardi, G. Crotti, and D. Morin, "Contactless Measurement of Hysteretic Transport ac Losses in Multifilamentary BiSrCaCuO-2223/Ag Tapes." To be published in Physica C (in press). Institute of Electrical Engineering, Slovak Academy of Sciences, 84239 Bratislava, SLOVAKIA; telephone +421 7 378 2353; telefax +421 7 375 816; e-mail elekgomo@savba.sk. Key words: transport, ac losses, multifilamentary high-Tc tapes, flux pinning.
Grzegorz Gorski and Jerzy Mizia, "Electronic Pairing Due to Interband and Intraband Hopping Dependence on Oxygen Covalency in YBaCuO Superconductors." To be published in Physica C (in press). Contact Jerzy Mizia, Institute of Physics, Pedagogical University of Rzeszow, ul. Rejtana 16A, 35-958 Rzeszow, POLAND; telephone +48 17 8522 101; telefax +48 17 8522 044. Key words: electronic model, intraband hopping, Coulomb correlations, pairing potential. 74.20.-z; 74.20.Fg; 74.20.Mn.
Yasumasa Hasegawa, "Josephson Current Between Triplet and Singlet Superconductors." To be published in J. Phys. Soc. Jpn. Faculty of Science, Himeji Institute of Technology, Kamigori, Akou-gun, Hyogo 678- 1297, JAPAN; e-mail hasegawa@sci.himeji-tech.ac.jp; preprint also available at cond-mat@xxx.lanl.gov (#9809403). Key words: triplet superconductor, odd-parity, spin-orbit coupling, Josephson junction.
Terry G. Holesinger, John F. Bingert, Jeffrey O. Willis, Qi Li, Ronald D. Parrella, Mark D. Teplitsky, Martin W. Rupich, and Gilbert N. Riley, Jr., "Structural and Compositional Defects in High-Jc Bi-2223 Tapes." Presented at the 1998 Appl. Supercond. Conf. (ASC), Palm Desert, Calif., Sept. 13-18, 1998. Contact American Superconductor Corporation, Two Technology Drive, Westborough, MA 01581-1727; telephone (508) 836-4200; telefax (508) 836-4248; e-mail jcrail@amsuper.com.
A. Hosseini, R. Harris, Saied Kamal, P. Dosanjh, J. Preston, Ruixing Liang, W. N. Hardy, and D. A. Bonn, "Microwave Spectroscopy of Thermally Excited Quasiparticles in YBa2Cu3O6.99." Submitted to Phys. Rev. B. 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 (#9811041).
Ling Hua, Jaimoo Yoo, Jaewoong Ko, Haidoo Kim, Hyungsik Chung, and Guiwen Qiao, "Effect of Precursor Powders on Phase Evolution and Electromagnetic Properties of Controlled Melting Processed Bi-2223 Ag- Sheathed Tapes." To be published in Physica C (in press). Korea Institute of Machinery and Materials, 66 Sangnam-dong, Changwon 641-010 KOREA; telephone +82 551 80 3585; telefax +82 551 80 3599; e-mail lhua@usa.net. Key words: Bi-2223/Ag tapes, precursor powder, flux pinning, phase evolution. 74.25.Fy; 74.60.Ge; 74.60.Jg; 74.72.Hs.
Y. Huang, K. L. Merkle, B. H. Moeckly, and K. Char, "The Effect of Microstructure on the Electrical Properties of the YBCO Interface- Engineered Josephson Junctions." Submitted to Physica C. Contact B. H. Moeckly, Conductus, Inc., 969 W. Maude Avenue, Sunnyvale, CA 94086; telephone (408) 523-9452; telefax (408) 523-9999; e-mail moeckly@conductus.com.
Y. Imagawa, K. Kakimoto, and Y. Shiohara, "Effect of High Oxygen Partial Pressure Atmosphere for Melt-Processed YBa2Cu3O6+d Current Lead by Unidirectional Solidification." 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 5711; telefax +81 3 3536 5705. Key words: directional solidification, YBCO, high Jc, high oxygen pressure, current lead.
A. Jacobs, R. Kuemmel, and H. Plehn, "Proximity Effect, Andreev Reflections, and Charge Transport in Mesoscopic Superconducting- Semiconducting Heterostructures." Institut fuer Theoretische Physik, Universitaet Wuerzburg, Am Hubland, D-97074 Wuerzburg, GERMANY; e-mail jacobs@physik.uni-wuerzburg.de; preprint also available at cond- mat@xxx.lanl.gov (#9810343).
Beom Jun Kim, Gun Sang Jeon, M.-S. Choi, and M. Y. Choi, "Quantum Phase Transitions in Superconducting Arrays under External Magnetic Fields." To be published in Phys. Rev. B. Department of Theoretical Physics, Umea University, 901 87 Umea, SWEDEN; e-mail kim@tp.umu.se; preprint also available at cond-mat@xxx.lanl.gov (#9810221). 74.50.+r; 67.40.Db.
Ji-Yeon Kim, Su-Young Lee, In-Sang Yang, T. G. Lee, S. S. Yom, Kibum Kim, and Jae Hoon Kim, "Raman and Infrared Spectroscopy of YBa2Cu3O7-d- BaPbO3 Composites." To be published in Physica C (in press). Contact In-Sang Yang, Department of Physics, Ewha Womans University, Seoul 120- 750, SOUTH KOREA; telephone +82 2 360 2332; telefax +82 2 360 2372; e- mail yangmm.ewha.ac.kr. Key words: Raman spectroscopy, infrared spectroscopy, YBa2Cu3O7-d, BaPbO3, intergranular material. 74.72.-h; 78.30.-j; 74.80.-g.
Hiroyuki Kimura, Kazuma Hirota, Hiroki Matsushita, Kazuyoshi Yamada, Yasuo Endoh, Seung-Hun Lee, Charles F. Majkrzak, Ross Erwin, Gen Shirane, Martin Greven, Young S. Lee, Marc A. Kastner, and Robert J. Birgeneau, "Neutron Scattering Study of Static Antiferromagnetic Correlations in La2-xSrxCu1-yZnyO4." Department of Physics, Tohoku University, Aramaki Aoba, Sendai 980-8578, JAPAN; Robert J. Birgeneau's telephone at MIT, Cambridge, Mass. (617) 253-8900. 74.72.Dn; 75.10.Jm; 75.50.Ee.
A. Kraemer, "Entanglement of Flux Lines in Superconductors with Finite Thickness." To be published in Physica C (in press). Department of Applied Physics, Stanford University, Stanford, CA 94305; telephone (650) 723-0219; telefax (650) 725-2189; e-mail kramer@drizzle.stanford.edu. Key words: flux lines, finite thickness, Kosterlitz-Thouless.
A. V. Kuznetsov, D. V. Eremenko, and V. N. Trofimov, "Onset of Flux Penetration into a Thin Superconducting Film Strip." To be published in Phys. Rev. B. Department of Quantum Electronics, Moscow State Engineering Physics Institute, Kashirskoe shosse 31, 115409 Moscow, RUSSIA; e-mail kuzn@htsc.mephi.ru. 74.60.Ec; 74.60.Ge; 74.60.Jg; 74.76.Bz.
Hyok-Jon Kwon, "Order Parameter Fluctuation Effects in d-Wave BCS Superconductors." 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 (#9811059).
H. K. Lee, "Synthesis and Superconductivity of a New Type of Pb-1212 Phase (Pb,V)Sr2(Ca,Y)Cu2Oz." To be published in Physica C (in press). Department of Physics, Kangwon National University, Chunchon 200-702, SOUTH KOREA. Key words: synthesis, superconductivity, (Pb,V)Sr2(Ca,Y)Cu2Oz, annealing.
Sergey Lee, T. Akao, H. Suematsu, H. Yamauchi, N. P. Kiryakov, D. A. Emelyanov, and M. S. Kuznetsov, "Enhanced Pinning and Peak Effect in Overdoped (Hg,Pb)(Sr,Ba)2Ca2Cu3O8+d Superconductors." Submitted to Appl. Phys. Lett. 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.
R. L. Leheny, R. J. Christianson, R. J. Birgeneau, and R. W. Erwin, "Spin Correlations in an Isotropic Spin-5/2 Two-Dimensional Antiferromagnet." Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139; R. J. Birgeneau's telephone (617) 253- 8900. 75.10.Jm; 75.50.Ee; 75.40.Cx; 64.60.Kw.
Y. Li, P.V.P.S.S. Sastry, D. C. Knoll, S. C. Peterson, and J. Schwartz, "Synthesis of HgPb1223 Superconductor." Submitted to IEEE Trans. Appl. Supercond. National High Magnetic Field Laboratory, Florida State University, 1800 East Paul Dirac Drive, Tallahassee, FL 32310; P.V.P.S.S. Sastry's telephone (850) 644-1447; telefax (850) 644-0867; e- mail pamidi@magnet.fsu.edu.
G. Litak, B. L. Gyoerffy, and K. I. Wysokinski, "Charge and Order Parameter Fluctuations in Disordered Superconductors." To be published in Physica C (in press). Department of Mechanics, Technical University of Lublin, Nadbystrzycka 36, PL-20618 Lublin, POLAND; telefax +48 815 25 0808; e-mail litak@tytan.umcs.lublin.pl. Key words: disordered superconductors, fluctuations, charge density wave. 71.55.-i; 74.40.+k; 71.45.Lr.
M. Lorenz, H. Hochmuth, D. Natusch, G. Lippold, V. L. Svetchnikov, T. Kaiser, M. A. Hein, R. Schwab, and R. Heidinger, "Ag-Doped Double-Sided PLD-YBCO Thin Films for Passive Microwave Devices in Future Communication Systems." Submitted to IEEE Trans. Appl. Supercond.: Proc. of the 1998 Appl. Supercond. Conf. (ASC), Palm Desert, Calif., Sept. 13-18, 1998. Fakultaet fuer Physik und Geowissenschaften, Universitaet Leipzig, Linnestr. 5, D-04103 Leipzig, GERMANY; e-mail mlorenz@physik.uni-leipzig.de.
Shahnaz Malik and Riaz Ahmed, "An Investigation of the Nature of Copper Species in High Tc Superconductor YBa2Cu3O7-d and in Other Compounds by Cyclic Voltammetry." SSO, NCD PINSTECH (Pakistan Institute of Science & Technology), Nilore, Islamabad, PAKISTAN; telephone +92 51 84 76019.
A. P. Malozemoff, W. Carter, S. Fleshler, L. Fritzemeier, Q. Li, L. Masur, P. Miles, D. Parker, R. Parrella, E. Podtburg, G. N. Riley, Jr., M. Rupich, J. Scudiere, and W. Zhang, "HTS Wire at Commercial Performance Levels." Presented at the 1998 Appl. Supercond. Conf. (ASC), Palm Desert, Calif., Sept. 13-18, 1998. American Superconductor Corporation, Two Technology Drive, Westborough, MA 01581-1727; telephone (508) 836-4200; telefax (508) 836-4248; e-mail jcrail@amsuper.com.
Michael D. Manlief, Herve Picard, Greg Snitchler, A. K. Ghosh, M. Harrison, W. B. Sampson, P. Wanderer, Gerald Dugan, Joseph Rogers, Alexander Temnykh, Jeffrey S. Brandt, Peter J. Limon, and Romesh C. Sood, "The Performance of Bi-Sr-Ca-Cu-O Superconducting Quadrupole Coils." Presented at the 1998 Appl. Supercond. Conf. (ASC), Palm Desert, Calif., Sept. 13-18, 1998. American Superconductor Corporation, Two Technology Drive, Westborough, MA 01581-1727; telephone (508) 836- 4200; telefax (508) 836-4248; e-mail jcrail@amsuper.com.
Damian Marinaro and Oleg Sushkov, "Superconductivity and Spin Triplet Collective Mode in the t-J Model Close to Antiferromagnetic Instability." Report #UNSW-98-c; to be published in Phys. Rev. B. School of Physics, University of New South Wales, Sydney 2052, AUSTRALIA; e-mail sushkov@phys.unsw.edu.au; preprint also available at cond-mat@xxx.lanl.gov (#9810141). 71.27.+a; 74.20.Hi; 75.50.Ee.
D. Mou, J. Linnros, C. S. Petersson, and K. V. Rao, "Electrical Properties of Epitaxial PbTiO3/YBa2Cu3O7-x Heterostructures." To be published in Physica C (in press). Department of Electronics, Royal Institute of Technology, Box E229, S-164 40 Kista, SWEDEN; telefax +46 8 752 7782; e-mail duan@ele.kth.se. Key words: YBa2Cu3O7-x superconductor, heterostructures, ferroelectric film. 74.76.Bz; 77.80.- e; 73.40.-c.
N. A. Nemov and V. R. Belosludov, "Phase Diagram and Phase Separation of Cuprate Oxides in Decorated Ising Model." To be published in Physica C (in press). Institute of Inorganic Chemistry, Siberian Branch of Russian Academy of Sciences, Lavrentiev Avenue 3, Novosibirsk 630090, RUSSIA; e-mail nemov@casper.che.nsk.su. Key words: phase diagram, frustrations, Cu-O planes, phase separation.
R. Noetzel, Th. Meier, K. Westerholt, R. G. Mustafin, and N. M. Suleimanov, "Superconducting Properties of Hydrogenated Bi2Sr2CaCu2O8+d Single Crystals." To be published in Physica C (in press). Institut fuer Experimentalphysik IV, Ruhr-Universitaet, D-44780 Bochum, GERMANY; telephone +49 234 700 3647; telefax +49 234 7094 173; e-mail ralf.noetzel@rz.ruhr-uni-bochum.de. Key words: superconducting properties, Bi2Sr2CaCu2O8+d, single crystals.
I. M. Obaidat, S. J. Park, and J. S. Kouvel, "Vortex Behavior in a Rotated YBa2Cu3O7-d Polycrystal." To be published in Physica C (in press). Contact J. S. Kouvel, Room 2236, Department of Physics, University of Illinois, 845 W. Taylor Street, Chicago, IL 60607-7059; telephone (312) 996-3400; telefax (312) 996-9016. Key words: vortex, YBa2CuO7-d, polycrystal.
A. V. Pan, R. Hoehne, M. Ziese, P. Esquinazi, and C. Assmann, "Evidence for Two Vortex Species in Niobium Films in Parallel Fields." To be published in Phys. and Mater. Sci. of Vortex States, Flux Pinning, and Dynamics: Proc. of the NATO Adv. Study Inst., Kusadasi, Turkey, July 26-Aug. 8, 1998, edited by S. Bose and R. Kossowski (Kluwer, 1999). Department of Superconductivity and Magnetism, Universitaet Leipzig, Linnestrasse 5, D-04103 Leipzig, GERMANY; e-mail pan@physik.uni- leipzig.de.
T. Puig, X. Obradors, B. Martinez, and J. A. Alonso, "Enhanced Interface Pinning and Aging by High Pressure Oxygenation of Melt Textured Nd1+xBa2-xCu3O7-d." To be published in Physica C (in press). Institut de Ciencia de Materials de Barcelona, C.S.I.C., Campus Universitat Autonoma de Barcelona, E-08193 Bellaterra, SPAIN; telephone +34 93 580 1853; telefax +34 93 580 5729; e-mail teresa.puig@icmab.es. Key words: critical current density, fishtail effect, flux pinning, oxygen stoichiometry.
A. J. Rodenbush, D. Aized, and B. B. Gamble, "Conduction and Vapor Cooled HTS Power Leads for Large Scale Applications." Presented at the 1998 Appl. Supercond. Conf. (ASC), Palm Desert, Calif., Sept. 13-18, 1998. American Superconductor Corporation, Two Technology Drive, Westborough, MA 01581-1727; telephone (508) 836-4200; telefax (508) 836- 4248; e-mail jcrail@amsuper.com.
A. J. Rodenbush and S. J. Young, "Performance of High Temperature Superconducting Coils for Implementation into Megawatt Class Generators." Presented at the 1998 Appl. Supercond. Conf. (ASC), Palm Desert, Calif., Sept. 13-18, 1998. American Superconductor Corporation, Two Technology Drive, Westborough, MA 01581-1727; telephone (508) 836- 4200; telefax (508) 836-4248; e-mail jcrail@amsuper.com.
M. W. Rupich, W. Palm, W. Zhang, E. Siegal, S. Annavarapu, L. Fritzemeier, M. D. Teplitsky, C. Thieme, and M. Paranthaman, "Growth and Characterization of Oxide Buffer Layers for YBCO Coated Conductors." Presented at the 1998 Appl. Supercond. Conf. (ASC), Palm Desert, Calif., Sept. 13-18, 1998. American Superconductor Corporation, Two Technology Drive, Westborough, MA 01581-1727; telephone (508) 836-4200; telefax (508) 836-4248; e-mail jcrail@amsuper.com.
Alexey V. Samokhvalov, "Expanding Vortex Rings in a Current-Carrying Superconducting Cylinder." To be published in Physica C (in press). Institute for Physics of Microstructures, Russian Academy of Sciences, 603600 Nizhny Novgorod, RUSSIA; telephone +7 8312 675 037; telefax +7 8312 675 553; e-mail samokh@ipm.sci-nnov.ru. Key words: critical current density, type-II superconductors, mixed state.
P.V.P.S.S. Sastry and J. Schwartz, "Synthesis and Stability of HgRe1212 and HgRe1223 Superconductors." To be published in IEEE Trans. Appl. Supercond. National High Magnetic Field Laboratory, Florida State University, 1800 East Paul Dirac Drive, Tallahassee, FL 32310; telephone (850) 644-1447; telefax (850) 644-0867; e-mail pamidi@magnet.fsu.edu.
G. W. Schulz, C. Klein, H. W. Weber, S. Moss, R. Zeng, S. X. Dou, R. Sawh, Y. Ren, and R. Weinstein, "Enhancement of Transport Critical Current Densities in Bi2Sr2Ca2Cu3Ox Tapes by Fission Tracks." To be published in Appl. Phys. Lett. Atomic Institute of the Austrian Universities, Schuettelstrasse 115, A-1020 Vienna, AUSTRIA; H. W. Weber's e-mail weber@ati.ac.at. 74.60.Ge; 74.60.Jg; 74.62.Dh; 74.72.Hs.
Sharad K. Singh, David W. Scherbarth, Ernest S. Ortoli, Jeffrey R. Repp, Owen R. Christianson, James H. Parker, Jr., James W. Carr, Jr., Gregory L. Rhoads, Charles E. Oberly, and Bruce Gamble, "Conceptual Design of a High Temperature Superconducting Generator." Presented at the 1998 Appl. Supercond. Conf. (ASC), Palm Desert, Calif., Sept. 13-18, 1998. Contact American Superconductor Corporation, Two Technology Drive, Westborough, MA 01581-1727; telephone (508) 836-4200; telefax (508) 836- 4248; e-mail jcrail@amsuper.com.
P. Skov-Hansen and Z. Han, "Stresses and Strains in Multi-Filament HTS Tapes." Submitted to IEEE Trans. Appl. Supercond.: Proc. of the 1998 Appl. Supercond. Conf. (ASC), Palm Desert, Calif., Sept. 13-18, 1998. Nordic Superconductor Technologies A/S, Prioparken 878, DK-2605 Brondby, DENMARK; telephone +45 4348 3545; telefax +45 4348 2501; e-mail p.hansen@nst.com.
G. Snitchler, S. S. Kalsi, M. Manlief, R. E. Schwall, A. Sidi-Yekhlef, S. Ige, R. Medeiros, T. L. Francavilla, and D. U. Gubser, "High-Field Warm-Bore HTS Conduction Cooled Magnet." Presented at the 1998 Appl. Supercond. Conf. (ASC), Palm Desert, Calif., Sept. 13-18, 1998. American Superconductor Corporation, Two Technology Drive, Westborough, MA 01581-1727; telephone (508) 836-4200; telefax (508) 836-4248; e-mail jcrail@amsuper.com.
V. Sokolovsky and V. Meerovich, "Heating Due to ac Losses in High- Temperature Superconductors." To be published in Physica C (in press). Department of Physics, Ben-Gurion University of the Negev, P.O. Box 653, 84105 Beer-Sheva, ISRAEL; telephone +972 7 647 2903; telefax +972 7 647 2458; e-mail victorm@bgumail.bgu.ac.il. Key words: high-Tc superconductors, ac losses, heating, critical state model.
T. Sueyoshi, N. Ishikawa, A. Iwase, Y. Chimi, T. Kiss, T. Fujiyoshi, and K. Miyahara, "Transport Characteristics Near the Glass-Liquid Transition Temperature Before and After Heavy-Ion Irradiation in a YBa2Cu3O7-d Thin Film." To be published in Physica C (in press). Department of Electrical and Computer Engineering, Kumamoto University, Kumamoto 860- 8555, JAPAN; telephone +81 96 342 3849; telefax +81 96 342 3630; e-mail tetsu@eecs.kumamoto-u.ac.jp. Key words: flux pinning, E-J characteristics, glass-liquid transition, irradiation effect. 74.60.Ge; 74.72.Bk; 74.76.Bz.
J. D. Suh, B. Y. Chang, I. S. Yang, H. S. Kim, J. Y. Lee, D. K. Kim, C. H. Kim, and G. Y. Sung, "Cubic Y-Ba-Cu-O Thin Films by High Speed Pulsed Laser Deposition." To be published in Physica C (in press). Electronics and Telecommunications Research Institute, P.O. Box 106, Yusong, Taejon 305-600, SOUTH KOREA; telephone +82 42 860 6030; telefax +82 42 860 6836; e-mail jdsuh@ard.etri.re.kr. Key words: cubic YBCO, high deposition rates, high-speed PLD, cation kinetics. 74.62.-c; 74.72.Bk; 74.76.Bz.
C.L.H. Thieme, S. Fleshler, D. M. Buczek, M. Jowett, L. G. Fritzemeier, P. N. Arendt, S. R. Foltyn, J. Y. Coulter, and J. O. Willis, "Axial Strain Dependence at 77 K of the Critical Current of Thick YBaCuO Films on Ni-Alloy Substrates with IBAD Buffer Layers." Presented at the 1998 Appl. Supercond. Conf. (ASC), Palm Desert, Calif., Sept. 13-18, 1998. American Superconductor Corporation, Two Technology Drive, Westborough, MA 01581-1727; telephone (508) 836-4200; telefax (508) 836-4248; e-mail jcrail@amsuper.com.
V. N. Timofeev and I. G. Gorlova, "Growth Defects in BSCCO (2212) Single Crystal Whiskers." To be published in Physica C (in press). Contact I. G. Gorlova, Institute of Radioengineering and Electronics, Russian Academy of Sciences, Mokhovaya 11, Moscow 103907, RUSSIA; telephone +7 095 203 4976; telefax +7 095 203 8414; e-mail gorl@mail.cplire.ru. Key words: BSCCO, whiskers, defect structure, transmission electron microscopy. 68.70.+w; 61.16.Bg; 61.72.Ff.
A. Veneva, I. Iordanov, L. Toshev, A. Stoyanova-Ivanova, and D. Gogova, "A Study of the Effect of KCIO3 Addition on the ac Susceptibility and Microstructure of High-Temperature (Tc^[onset] at 105 K) YBCO Ceramic Superconductors." To be published in Physica C (in press). Superconductivity Research Laboratory, International Superconductivity Technology Center (ISTEC), 16-25 Shibaura 1-chome, Minato-ku, Tokyo 105- 0023, JAPAN; telephone +81 3 3454 9287; telefax +81 3 3454 9284; e-mail anjela@istec.or.jp. Key words: KCIO3-doped YBCO, K2CO3-doped YBCO, ac susceptibility YBCO, miocrostructure, YBCO ceramic preparation.
L. Ya. Vinnikov, T. L. Barkov, B. Irmer, K. Kragler, and G. Saemann- Ischenko, "Vortex Arrays in the BSCCO(2212) Single Crystals in the Vicinity of Steps on the Sample Surface." To be published in Physica C (in press). Institute of Solid State Physics, Russian Academy of Sciences, 142432 Chernogolovka, Moscow District, Moscow, RUSSIA. Key words: vortex arrays, BSCCO(2212), Meissner rim.
S. Wakimoto, K. Yamada, S. Ueki, G. Shirane, Y. S. Lee, S. H. Lee, M. A. Kastner, K. Hirota, P. M. Gehring, Y. Endoh, and R. J. Birgeneau, "Neutron Scattering Study of Elastic Magnetic Signals in Superconducting La1.94Sr0.06CuO4." Department of Physics, Tohoku University, Aramaki Aoba, Sendai 980-8578, JAPAN; R. J. Birgeneau's telephone at MIT, Cambridge, Mass. (617) 253-8900. Key words: superconductors, crystal growth, neutron scattering, magnetic properties, superconductivity.
N. L. Wang, A. W. McConnell, B. P. Clayman, and G. D. Gu, "Doping Dependence of the Pseudogap in the ab Plane Infrared Spectra of Bi2Sr2Ca1-xYxCu2O8+d." To be published in Phys. Rev. B (in press). Department of Physics, Simon Fraser University, Burnaby, BC, CANADA V5A 1S6; telephone (604) 291-4843; telefax (604) 291-9136; e-mail nlwang@sfu.ca. 74.25.Gz; 74.25.Dw; 74.25.Jb; 74.72.Hs.
Z. H. Wang, K. B. Li, Z. Y. Chen, H. Zhang, and X. W. Cao, "Pinning of Planar Defects Along the c-Axis in Epitaxial YBa2Cu3O7-d Thin Films." Submitted to Physica C. Shanghai Institute of Metallurgy, Chinese Academy of Sciences, Shanghai 200050, PEOPLE'S REPUBLIC OF CHINA; telephone +86 21 6251 1070, ext. 8924; telefax +86 21 6251 3510; e-mail zhwang@itsvr.sim.ac.cn. 74.60.Ge; 74.76.Bz; 74.25.Fy.
Jeffrey O. Willis, David. E. Daney, Martin P. Maley, J. Yates Coulter, and Steven Fleshler, "Single and Multi-Phase ac Losses in HTS Prototype Power Transmission Conductors." Presented at the 1998 Appl. Supercond. Conf. (ASC), Palm Desert, Calif., Sept. 13-18, 1998. Contact American Superconductor Corporation, Two Technology Drive, Westborough, MA 01581- 1727; telephone (508) 836-4200; telefax (508) 836-4248; e-mail jcrail@amsuper.com.
X. S. Wu, S. S. Jiang, J. Lin, J. S. Liu, W. M. Chen, and X. Jin, "Microstructural Variations of YBa2Cu3Oy Doped with Ca at High Doping Level." To be published in Physica C (in press). National Laboratory of Solid State Microstructures, Department of Physics, Institute for Solid State Physics and Center for Advanced Studies in Science and Technology of Microstructures, Nanjing University, Nanjing 210093, PEOPLE'S REPUBLIC OF CHINA; e-mail xswu@netra.nju.edu.cn. Key words: YBa2Cu3Oy, solid-state reaction, superconducting critical temperature. 61.10.-i; 74.62.Bf; 74.72.Bk.
W. L. Yang, H. H. Wen, Y. M. Ni, J. W. Xiong, H. Chen, C. Dong, F. Wu, Y. L. Qin, and Z. X. Zhao, "Crystal Growth and Superconductivity of Heavily La-Doped Bi-2201 Single Crystals." To be published in Physica C (in press). Contact H. H. Wen, National Laboratory of Superconductivity, Institute of Physics and Center for Condensed Matter Physics, Beijing 100080, PEOPLE'S REPUBLIC OF CHINA; telephone +86 10 6258 2179; telefax +86 10 6253 8834; e-mail hhwen@ssc.iphy.ac.cn. Key words: substitution effect, phase diagram, antiferromagnetic order.
Hideo Yoshioka and Yoshikazu Suzumura, "Response Functions of Two- Coupled Chains of Tomonaga-Luttinger Liquids." To be published in Physica C (in press). Department of Applied Physics, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, THE NETHERLANDS. Key words: Tomonaga-Luttinger liquids, two chains, response functions, superconductivity.
COMING EVENTS (An * indicates a previously listed event.)
Jan. 12 - 13, 1999: 7th Annual HTS Wire Development Workshop, sponsored by the U.S. Department of Energy, Doubletree Hotel, Cocoa Beach, Florida. This two-day meeting brings together the leading U.S. scientists and engineers involved in research and development of high- temperature superconducting wire and electric-utility applications for the wire. In order to identify and address key research needs, discussion sessions are planned around the following themes: first- generation HTS wire, second-generation HTS wire, ac losses, projected performance and cost, and user requirements for HTS wires. Optional tour of the NASA-Kennedy Cryogenics and Materials Characterization Laboratories will be conducted the afternoon of January 13. For more information contact Zia Haq, Energetics, Inc.; telephone (202) 479-2748, ext. 115; e-mail zhaq@energeticsinc.com or Dean Peterson, Los Alamos National Laboratory, telephone (505) 665-3030; e-mail dpeterson@lanl.gov.
Feb. 3 - 5, 1999: The 23rd Annual Condensed Matter Physics Meeting, Convention Centre, Charles Sturt University, Wagga Wagga, Australia. Emphasis on poster papers, plus invited keynote and postgraduate speakers on a wide range of research topics. Contributed and invited papers can cover any aspect of condensed-matter physics. Abstract deadline, December 11, 1998. For further Information, contact Robert G. Clark, Conference Chairman, School of Physics, UNSW; phone +61 2 9385 4574; fax +61 2 9385 6138; e-mail r.clark@unsw.edu.au. Or contact Renata Jones, Conference Secretary, phone +61 2 9385 4644, fax +61 2 9385 6138, e-mail renata@ jupiter.phys.unsw.edu.au.
May 31 - June 4, 1999: The Second International Conference on New Theories, Discoveries and Applications of Superconductors and Related Materials (New3SC-2), Circus Circus Hotel, Las Vegas, Nevada. Conference will carry out "open-door" policy in accepting contributions. Will focus on new ideas, new concepts, and new models of the mechanism and origin of superconduc-tivity, especially those new results that appear to exhibit a breakthrough either conceptually or in the applications they generate. The intent is to highlight the contributions of young and lesser-known researchers as well as those of senior scientists. Organizers will encourage and foster friendly and peaceful debates at the conference concerning whether or not a new physical picture is needed to fully understand both low- and high- temperature superconductivity. For more information, contact J. D. Fan, New3SC-2 Chair, P.O. Box 9767, Baton Rouge, LA 70813; telephone and telefax (225) 771-3926; e-mail new3sc@grant.phys.subr.edu; Web site http://www.phys.subr.edu/conference/new3sc.htm.
June 27 - 30, 1999: 1999 International Workshop on Superconductivity (4th Joint ISTEC/MRS Hawaii Workshop), Kauai, Hawaii. Co-sponsored by ISTEC and MRS. Fourth in the series. Theme will be "High-Temperature Superconducting Materials and Devices for Electronics Applications." In particular, topics concerning thin films and processing, and HTS junctions and integration technology will be emphasized. Workshop will consist mainly of a series of single-session meetings with a significant amount of time allotted for the discussion of each paper and extra amounts of time put aside to encourage informal interactions among the participants. Topics of interest (including, but not restricted to the following) are: HTS superconducting materials; characterization (surface roughness, surface resistance, etc.) and processing of thin films (MOCVD, LEP, sputtering, laser ablation, evaporation, etc.); substrates; HTS junctions; devices (microwave & mm-wave devices, SQUIDs, RSFQ/SFQ, JJs, etc.); applications (telecommunication, computing, switching devices, medical, etc.); and others. Contributed Summary deadline, January 15, 1999. For information, contact Tetsuji Kobayashi, Director, International Affairs Department, International Superconductivity Technology Center (ISTEC), Eishin Kaihatsu Bldg. 6F, 34-3, Shinbashi 5-chome, Minato-ku, Tokyo, 105-0004 Japan; phone +81 3341 4044; e-mail t-kobayashi@istec.or.jp.
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, #23, Dec. 1, 1998.