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, ONR, NSF, EPRI, and other agencies, organizations, and individuals.
The High-Tc Update web page is located at the URL http://www.iitap.iastate.edu/htcu/htcu.html
PLEASE NOTE: Issues of High-Tc Update from November 15, 1993, onward are also available in coded Word versions (BINHEX and RTF). (These versions preserve the Greek letters, special characters, accents, etc.) If you are interested in the alternate formats, contact the editor for information.
PLEASE READ: The electronic-mail version of High-Tc Update is generated from a Macintosh Microsoft Word file and turned into a text file that can be transferred electronically. Formatting commands, Greek symbols, diacritical marks, etc. are lost in this transformation. In order to improve the readability of the e-mail version, the newsletter staff add explanatory marks as needed to the text file. For example, a carat (10^5) indicates a superscript (ten to the fifth). A carat followed by a bracket (cm^[-2]) indicates everything within the brackets is superscripted (centimeter to the minus 2). A bracket followed by a carat ([18]^O) indicates everything before the carat is superscripted. An underline (M_i) indicates a subscript (M subscript i). Most Greek letters are spelled out (Delta, mu, tau, pi, Omega), although delta is left as "d." In most instances, easily recognizable formulas or units are left as they appear: Tc, Jc, YBa2Cu3O7, O2. Mu-m is changed to micrometers. Diacritical marks (accents, tildes, carats, etc.) are removed, but the German umlaut (e.g., a, o, or u with two dots over it) is changed into a, o, or u followed by e. If needed for clarity, hyphens are occasionally inserted between spelled-out Greek letters or symbols (ohm-cm, sin-theta).
NOTA BENE: Our Science Editor, John R. Clem, is currently on travel. The following Nota Bene is contributed by Sreeparna Mitra, Project Director and Editor of High-Tc Update.
A Reminder: Please note that the main purpose of High-Tc Update is to make information available about PREPRINTS and not REPRINTS that have already been published in a journal or book. In order to assure that your paper is listed in the Update, please send us your manuscript (hard copy or fax please, we do not have the resources to handle e-mail submissions!) early enough so it is not already published by the time we receive it.
Bi Cuprates
Angle-resolved photoemission spectra both above and below Tc are reported in a paper by J. M. Harris (Stanford) et al. for the single- plane cuprate superconductor Bi2Sr2-xLaxCuO6-d. Measurements for the superconducting state show a highly anisotropic excitation gap with a maximum magnitude a factor of three smaller than that of the bilayer compound Bi2Sr2CaCu2O8. The authors observe that the gap persists well above Tc for a range of doping, and the anisotropy and magnitude of the normal-state gap is similar to the superconducting-state gap suggesting that the two may have a common origin in a pairing interaction.
Effects of Li intercalation on the structural and superconducting properties of single phase Bi-2212 were investigated by M. Fujiwara (Okayama) et al. by using an electrochemical method for preparation of samples of LiyBi2Sr1.5Ca1.5Cu2Oz in the range of 0 <= y <= 0.37. The authors note that the electrochemical intercalation led to a drastic change of Tc; as y increased, Tc reached a maximum of 94 K and then decreased to zero, while the original tetragonal structure and oxygen content remained the same. The authors attribute the rapid Tc change to a decrease in hole concentration and note that the method provides a simple way of controlling the critical temperature by changing electrochemical conditions while maintaining the original crystal symmetry.
Effects of oxygen doping and structural distortion on the superconductivity of Bi2Sr2CaCu2Oy were studied by ac susceptibility and x-ray diffraction measurements for a group of high-quality single crystals by X. Sun (Academia Sinica) et al. The relationship between superconductivity, oxygen content, and microstructure of Bi-2212 crystals are discussed.
Another preprint by X. Sun (Academia Sinica) et al. reports the growth of Bi2Sr1.5Pr2.5Cu2Oy single crystals from off-stoichiometric melts by a directional solidification method. The crystals, characterized by x-ray analysis, were found to be similar to the Bi-2223 phase.
The amorphization occurring during mechanical grinding of BPSCCO has been investigated by E. Bruneel (Gent) et al. Using XRD, SEM, and TEM, the authors show that visually determined grain size and actual crystal size diminish upon grinding, that different crystal planes exhibit variable sensitivity toward the amorphization process, and that high-Tc Bi phases are more sensitive to this phenomenon that the low-Tc phases.
YBCO
Properties of the system (Y1-yCay)BaSrCu3-zCrzO7 for three materials with different compositions has been investigated by R. A. Jennings et al. (Birmingham). The authors correlate superconducting properties with structural and electronic changes deduced from neutron diffraction data and report that while Tc remains constant, the hole density within the superconducting CuO2 sheets increases with Ca doping. The authors discuss the significance of this with respect to a proposed increase in the optimum hole density with Sr content in systems based on YBa2SrxCu3O7.
A preprint by P. Dai (Oak Ridge) et al. reports inelastic neutron scattering results on YBa2Cu3O6.6. The authors find that the low frequency magnetic fluctuations are incommensurate at low temperatures, with incommensuration first appearing at temperatures above Tc. The dynamic susceptibility at incommensurate positions increases on cooling below Tc, accompanied by a suppression of magnetic fluctuations at the commensurate point.
Relationships between critical current density Jc and crystalline imperfections in YBa2Cu3Ox single crystals are investigated in a preprint by H. Asaoka et al. (Japan Atomic Research Inst.). Crystals were grown under various conditions of the melt phase and solid Y2BaCuO5 (211) existing together. By decreasing the melt composition in the coexisting region, the authors observe an increase in the concentration of voids, with Jc and the effective pinning energy is considerably enhanced.
Anomalous weight behavior in a supercooled YBa2Cu3O7 disk is reported in a preprint by F. N. Rounds (NASA-Ames).
Other Materials
Thermogravimetric analysis by J. L. Kissick (Birmingham) et al. has revealed that reduction of Sr2CuO2F2+d (10%H2/90%N2) occurs in two distinct steps upon heating up to 930^oC. The study shows that a stable intermediate region forms between 250^oC and 450^oC, after which the reduction is completed above 800^oC to yield SrF2, SrO, and Cu. From x- ray diffraction studies, the authors determine the intermediate structure as a new tetragonal (I4/mmm) phase, Sr2CuO2F2, related to Nd2CuO4 (T' type) which contrasts with the La2CuO4 (T type) structure adopted by Sr2CuO2F2+d.
The effect of high-temperature annealing on the superconducting transition and flux-pinning properties of Nd123 melt-textured in 1% O2- Ar has been investigated by N. Chikumoto (ISTEC) et al. The authors observe a decrease in Jc but no significant change in Tc, and show from TEM and EDX analysis that the spatial variation of the Nd/Ba ratio almost disappears after high-temperature annealing. The observed change in the Jc-B properties is explained as a reduction in the field-induced pinning due to homogenization of Nd/Ba substitution regions. The authors note that the results strongly support the idea that the secondary peak effect and high pinning performance in Nd123 can be ascribed to the presence of Nd/Ba spatial variation.
Theory
Equations describing the resistive state of a layered superconductor with anisotropic pairing are derived in a preprint by S. N. Artemenko et al. (Russian Academy of Sciences). The authors find similarity with a stack of Josephson junctions for small voltages only, and at higher voltages, the differential conductivity becomes negative. The authors conclude that nonuniformity of the current distribution generates the branch imbalance and violates the Josephson relation between frequency and voltage. The authors suggest that this may be the origin of the irregular character of the I-V curves observed in measurements of the intrinsic Josephson effect in high-Tc materials.
A preprint by M. Machida (Japan Atomic Energy Inst.) et al. reports numerical simulations of the I-V characteristics for a recent model for a stack of Josephson junctions proposed by Koyama and Tachiki [Phys. Rev. B 54 16183] that takes into account the charging effect of the superconducting layers. The authors find that hysteresis loops in the I-V curves show a multiple branch structure similar to those observed in single crystals of Bi-2212, and propose that this is caused by freezing of the collective longitudinal Josephson plasma modes into static charge density waves.
Transport properties of a quasi-two-dimensional diffusive normal-metal film attached to a superconductor are studied in a paper by F. K. Wilhelm (Karlsruhe) et al. The authors demonstrate that the properties of such films can essentially differ from those of the quasi-one- dimensional systems, and they develop a quantitative theory and discuss the physical nature of this effect.
A paper by D. Zanchi (Orsay) et al. investigates the weakly interacting two-dimensional Hubbard model using a one-loop renormalization approach and determines the value of Tc between the metallic and nearly ordered states.
Films
A preprint by A. Brazdeikis (Royal Institute) et al. describes fabrication of Hg-1212 thin films by a two-step procedure using amorphous precursor films fabricated by laser ablation, which are then post-annealed together with the corresponding metal oxides in closed tubes. The authors find that temperatures between 735^oC and 775^oC and annealing times of 30-60 minutes yielded optimal results. Films of best quality were obtained on SrTiO3 substrates, whereas films on MgO substrates were found to be non-continuous and comprised of micrometer strands of Hg-1212. Synthesis on LaAlO3 yielded mainly the lower homologue Hg-1201. Bulk material composition and residual impurity results are presented and surface morphologies, growth defects, and transport properties are discussed.
Measurements of the longitudinal and Hall resistivities in YBa2Cu3O7 thin films are reported in a paper by A. Casaca et al. (ITN) in fields up to 18 T. The authors report a signature due to the pinning of the vortices is clearly visible in the longitudinal resistivity rhoxx and in the Hall resisitivity rhoxy. The Hall conductivity is shown to be affected by the pinning in the twin boundaries as well, although this effect is weak and occurs for temperatures below TTB. The results are confirmed by the authors by similar measurements made on a sample rotated 16 degrees away from the magnetic field direction.
An anomalous magnetic field-effect has been observed by M. A. Hein (Wuppertal) et al. in the microwave surface impedance of epitaxial YBa2Cu3O7-x films on LaAlO3 substrates. The authors observe that application of dc and microwave magnetic fields up to 20 mT caused a significant decrease of microwave surface reactance and resistance at 8.5 GHz (77 K) and 87 GHz (4.2 K). The authors attribute the effect to the presence of magnetic impurities in the superconducting films that give rise to pair breaking. Alignment of the impurity spins suppresses the spin-flip scattering rate and as a result, leads to the recovery of superconductivity.
Perturbed angular correlation spectroscopy has been used by R. Platzer et al. (Oregon State) to study the tetragonal to orthorhombic transition in YBaCuO thin films. The authors observe a tetragonal to orthorhombic transition in the quenched oxygen-deficient films at 200^oC when the films are annealed in flowing oxygen. The transition is not reversible in flowing oxygen up to the decomposition temperature, in contrast to powders and single crystals, and cannot be completely reversed by cooling in flowing Ar.
A preprint by A. Andreone et al. (Napoli) presents penetration depth measurements in c-axis-oriented YBa2Cu3O7-d thin films performed by an inverted microchip method, using resonators of different geometries. The observed temperature dependence follows the Ginzburg-Landau (GL) behavior more closely than the dependence predicted by the 3D XY model. The experimental results are discussed in the light of recent models describing the effect of strong coupling on the lambda(T) behavior near Tc for an s-wave and a d-wave superconductor.
Epitaxial (Tl,Bi)-1223 films on RABiTS have been successfully synthesized by laser ablation by Z. F. Ren (Buffalo) et al. Transport measurements yielded Tc values in the range 106 K -110 K and Jc (77 K, 0 T) of 10^5 A/cm^2 on a longer film of 14 mm. A shorter film (7 mm) showed better ab in-plane alignment. The magnetization Jcs are calculated from Bean's model and compared to experimental results.
Tapes
Measurements of self-field ac losses by the conventional four-probe method are reported in a preprint by Y. Iijima (Fujikura) et al. for biaxially aligned YBCO tapes using Hastelloy tapes with textured YSZ buffer layers. In a high-Jc sample, the ac losses increased in proportion to the fourth power of transporting currents and fitted well with the Norris equation for thin strip conductors. However, a low-Jc sample had higher losses than the Norris prediction which suggests exceeding magnetic flux penetration caused by percolated current paths. The authors reaffirm the importance of removal of percolated structures of current paths to avoid increase of ac losses from theoretical predictions based on uniform conductors.
Ag-sheathed Bi2Sr2CaCu2Ox tapes were fabricated by C.F.J. Yue et al. (Gainesville) by a method combining electrophoretic deposition and mechanical consolidation techniques. The Jc of the tapes was approximately 10^5 A/cm^2 at 5 K. The mechanical properties and c-axis texturing of the BSCCO films in superconducting tapes improved when smaller-sized BSCCO powders were used and by introduction of an interlayer of Ag particles. Peel tests conducted on the samples suggest that the improvement in the fracture strength of the tapes was related to the plasticity of the Ag particle interlayer.
Vortices
Twin boundary pinning in a YBa2Cu3O7 single crystal has been investigated by T. Ishida (Osaka Prefecture) et al. in terms of the c- axis and ab-plane anisotropies of torque. The authors present evidence for a steep free-energy minimum and a sharp pinning peak when the field is applied parallel to the twin boundaries along either the c axis or the ab plane. The authors note that the directional pinning is very similar to the intrinsic pinning and discuss the temperature dependence of the twin boundary pinning. In another preprint, T. Ishida et al. present simultaneous measurements of the ac susceptibility and the dc magnetization of an untwinned single crystal of YBa2Cu3O7. The authors report a crossover change from pinned vortex liquid to free liquid and note that the effectual pinning force is active even at temperatures above the melting transition.
Magneto-optical observations of moving helicoidal vortex structures in high-purity YBa2Cu3O7-d single crystals are reported by G. D'Anna et al. (Lausanne). The authors find that the dynamics of these "vortex twisters" is mainly controlled by localized instabilities which stream along the helices, and the instabilities allow the motion of the twisters, or the annihilation of twisters with opposite chirality.
A paper by C. Ren (Buffalo) et al. presents evidence for plastic vortex liquid and its transition to a plastic solid for YBa2Cu3O7-d based on measurements of the effects of the ac field amplitude, frequency, and dc field B_d on the ac susceptibility. The authors propose a method for constructing the vortex liquid-solid transition line from ac susceptibility measurements.
A paper by A. A. Zhukov (Blackett Lab.) et al. presents evidence of a vortex-locking phenomenon in YBa2Cu3O7 single crystals. Measurements show that the direction of the vortices deviates from the applied field and is attracted to the twin-boundary planes. The authors assert that criteria for identifying the locking and trapping angles for the vortex interaction with twin boundaries and the dependence of these angles on the field and temperature are similar to those predicted by theory, but magnitudes are in disagreement.
Applications
A pyroelectric IR sensor based on oxide heterostructures on YSZ- bufferedSi (100) and LaAlO3 (100) substrates has been fabricated by N. J. Wu et al. (TCSUH). Pb(Zr,Ti)O3 (PZT) and (Sr,Ba)Nb2O6 (BSN) thin films were integrated to YBa2Cu3Ox (YBCO) films on the substrates by the pulsed-laser-deposition technique. The YBCO films are used both as IR reflector-conductive electrodes and as atomic templates for PZT and BSN epitaxial growth, but not for their superconductive properties. Detectivity values of ~10^8 cm Hz^[1/2]/W at room temperature have been obtained for simple heterostructure device configurations. The authors suggest that the tunable phase transition temperature, dielectric constant, and pyroelectric properties of the oxide allow for the development of an infrared detector with operation at temperatures higher than room temperature.
Contributed by Sreeparna Mitra
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.
A. Andreone, C. Cantoni, A. Cassinese, A. Di Chiara, and R. Vaglio, "Strong Coupling Effects on the Temperature Dependence of Penetration Depth in YBa2Cu3O7-d Thin Films Near Tc." Submitted to Phys. Rev. B. Dipartimento di Scienze Fisiche, Universita di Napoli "Federico II," Piazzale Tecchio 80, I-80125 Napoli, ITALY; telephone +39 81 768 2423; telefax +39 81 239 1821; e-mail andreone@na.infn.it. 74.76.Bz; 74.25.Nf; 74.20.De; 74.20.Mn.
S. N. Artemenko and A. G. Kobelkov, "Intrinsic Josephson Effect and Violation of the Josephson Relation in Layered Superconductors." To be published in Phys. Rev. Lett. Institute for Radioengineering and Electronics of the Russian Academy of Sciences, 103907 Moscow, RUSSIA; e-mail art@delta.cplire.ru; preprint also available at cond- mat@xxx.lanl.gov (#9704025). 74.50.+r; 74.80.Dm; 74.25.Fy.
Hidehito Asaoka, Yukio Kazumata, Humihiko Takei, and Kenji Noda, "Influence of Growth Condition on Magnetic Flux Pinning in YBa2Cu3Ox Single Crystals." To be published in Physica C (in press). Japan Atomic Energy Research Institute, Tokai-mura, Ibaraki 319-11, JAPAN; telephone +81 29 2826081; telefax +81 29 2825460; e-mail asaoka@maico.tokai.jaeri.go.jp. Key words: flux pinning, critical current density, SQUID, YBa2Cu3Ox, single-crystal growth.
F. Bass, B. Ya. Shapiro, and M. Shvartser, "Slow Magnetic Flux Diffusion in Type-II Superconductors." To be published in Solid State Commun. Department of Physics, Institute of Superconductivity, Bar-Ilan University, Ramat Gan 52900, ISRAEL. Key words: superconductivity, flux motion.
Stephane Belin and Kamran Behnia, "Thermal Conductivity of Superconducting (TMTSF)2CIO4: Evidence of a Nodeless Gap." Submitted to Phys. Rev. Lett. Contact Kamran Behnia, Laboratoire de Physique des Solides, Universite Paris-Sud, F-91405 Orsay, FRANCE; telefax +33 1 69 15 60 86; e-mail kamran@lps.u-psud.fr; preprint also available at cond- mat@xxx.lanl.gov (#9706019). 74.70.Kn; 74.25.Fy; 72.15.Eb.
J. Bok and J. Bouvier, "Comment on 'NMR Evidence for a d-Wave Normal- State Pseudogap.'" Submitted to Phys. Rev. Lett. Laboratoire de Physique du Solide UPR 5 CNRS, ESPCI, 10 rue Vauquelin, F-75231 Paris Cedex 05, FRANCE; J. Bouvier's telephone +33 1 40 79 44 09 51; telefax +33 1 40 79 44 25; e-mail bok@merlin.ens.fr.
H. Bougrine and M. Pekala, "Note on the Measurement of the Thermal Conductivity and the Double Peak Structure in High Tc Superconductors." To be published in Supercond. Sci. & Technol. SUPRAS, Montefiore Electricity Institute, B28, University of Liege, B-4000 Liege, BELGIUM. 06.60.Ei; 74.25.Fy; 74.72.Bk.
A. Brazdeikis, I. Bryntse, and A. S. Flodstroem, "Synthesis of Thin Superconducting HgBa2CaCu2O6+d Films by Post-Annealing of Laser-Ablated Precursors." To be published in J. Mater. Res. Texas Center for Superconductivity, University of Houston, Houston, TX 77204-5932; telephone (713) 743-8305; telefax (713) 743-8201; e-mail audrius@uh.edu; Web site http://www.matphys.kth.se/Information/Publications.html.
E. Bruneel, K. Verbist, L. Fiermans, and S. Hoste, "Amorphization During Mechanical Grinding of Bi-Pb-Sr-Ca-Cu-O Ceramic Superconductors." To be published in Appl. Supercond. Department of Inorganic and Physical Chemistry, Solid State and Superconducting Materials Division, Gent University, Krijgslaan 281, B-9000 Gent, BELGIUM; telephone +32 9 264 44 40; telefax +32 9 264 49 83; e-mail els.bruneel@rug.ac.be.
A. Casaca, G. Bonfait, M. Getta, M. Lenkens, and G. Mueller, "Twin Boundary Effect on the Hall Conductivity in High-Tc Superconducting Thin Films." To be published in Phys. Rev. B. Departamento de Quimica, Instituto Tecnologico e Nuclear, Estrada Nacional 10, P-2686 Sacavem Codex, PORTUGAL; telephone +351 1 955 00 21 (ext. 1347, 1306, or 1343); telefax +351 1 994 14 55; e-mail acasaca@itn1.itn.pt. 74.25.Fy; 74.60.Ge; 74.62.Dh; 74.76.Bz.
X. K. Chen, J. G. Naeini, K. C. Hewitt, J. C. Irwin, R. Liang, and W. N. Hardy, "Electronic Raman Scattering in Underdoped YBa2Cu3O6.5." To be published in Phys. Rev. B. Department of Physics, Simon Fraser University, Burnaby, BC, Canada V5A 1S6. 74.25.Gz; 74.72.Dn; 78.30.Er.
N. Chikumoto, J. Yoshioka, M. Otsuka, N. Hayashi, and M. Murakami, "Effect of High-Temperature Heat-Treatment on the Pinning Properties of Melt-Textured Nd123." To be published in Physica C. Superconductivity Research Laboratory, International Superconductivity Technology Center (ISTEC), 16-25 Shibaura 1-chome, Minato-ku, Tokyo 105, JAPAN. Key words: NdBa2Cu3O7-d, melt texture, high-temperature annealing, flux pinning, superconducting transition, peak effect.
Pengcheng Dai, H. A. Mook, and F. Dogan, "Incommensurate Magnetic Fluctuations in YBa2Cu3O6.6." Solid State Division, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN 37831-6393; telephone (423) 574-5233; telefax (423) 574-6268 or -4143; e-mail piq@ornl.gov. 74.72.Bk; 61.12.Ex.
G. D'Anna, W. Benoit, A. Semoroz, and V. Berseth, "Kinks and Vortex- Twister Dynamics in Type-II Superconductors." Submitted to Physica C. Instiut de Genie Atomique, Departement de Physique, Ecole Polytechnique Federale de Lausanne, CH-1015 Lausanne, SWITZERLAND; telephone +41 21 693 44 98; telefax +41 21 693 44 70; e-mail danna@igahpse.epfl.ch.
M. Fujiwara, M. Nakanishi, Y. Kusano, T. Fujii, J. Takada, Y. Takeda, and Y. Ikeda, "Electrochemical Lithium Intercalation into the Bi-2212 Phase." To be published in Physica C (in press). Department of Applied Chemistry, Faculty of Engineering, Okayama University, 3-1-1 Tsushima- naka, Okayama 700, JAPAN; telephone +81 86 2518106; telefax +81 86 2557900; e-mail jtakada@cc.okayama-u.ac.jp. Key words: electrochemical method, Bi-2212 phase, lithium intercalation, Tc, lattice parameter, oxygen content, Cu-valence. 74.72.-h.
A. Gurevich and E. A. Pashitskii, "Enhancement of Superconductivity at Structural Defects in High-Temperature Superconductors." Submitted to Phys. Rev. B. Applied Superconductivity Center, University of Wisconsin, Madison, WI 53706; telefax (608) 263-1087; e-mail gurevich@coefac.engr.wisc. edu. 74.20.De; 74.20.Hi; 74.60.-w.
J. M. Harris, P. J. White, Z.-X. Shen, H. Ikeda, R. Yoshizaki, H. Eisaki, S. Uchida, W. D. Si, J. W. Xiong, Z.-X. Zhao, and D. S. Dessau, "Measurement of an Anisotropic Energy Gap in Single Plane Bi2Sr2- xLaxCuO6+d." To be published in Phys. Rev. Lett. Department of Applied Physics and Stanford Synchrotron Radiation Laboratory, Stanford University, Stanford, CA 94305; e-mail jharris@ee.stanford.edu; preprint also available at cond-mat@xxx.lanl.gov (#9705305). 74.72.Hs; 74.25.-q; 74.25.Jb; 79.60.Bm; 71.18.+y.
M. A. Hein, Ch. Bauer, W. Diete, S. Hensen, T. Kaiser, V. Z. Kresin, and G. Mueller, "Magnetic Field-Induced Recovery of Superconductivity in Epitaxial YBa2Cu3O7-x Films at Microwave Frequencies." To be published in J. Supercond. Contact T. Kaiser, Fachbereich Physik, Bergische Universitaet Wuppertal, Gauss-Strasse 20, D-42097 Wuppertal, GERMANY; telephone +49 202 439 2860; telefax +49 202 439 2811; e-mail kaiser@wpos4.physik.uni-wuppertal.de. Key words: surface impedance, penetration depth, high-temperature superconductors, pair breaking, two- fluid model.
Y. Iijima, M. Hosaka, N. Sadakata, T. Saitoh, O Kohno, and K. Takeda, "Measurements of the Self-Field ac Losses in Biaxially Aligned Y-Ba-Cu-O Tape Conductors." Submitted to Appl. Phys. Lett. Materials Research Laboratory, Fujikura Ltd., 1-5-1 Kiba, Koto-ku, Tokyo 135, JAPAN; telefax +81 3 5606 1512; e-mail ijm@rd.fujikura.co.jp. Key words: superconducting films, ac loss.
T. Ishida, K. Okuda, H. Asaoka, Y. Kazumata, K. Noda, and H. Takei, "Clear Evidence for Vortex Pinning Along Twin Boundaries in a YBa2Cu3O7 Single Crystal." Presented at the 9th Int. Symp. on Supercond. (ISS'96), Sapporo, Hokkaido, Japan, Oct. 21-24, 1996. Department of Physics and Electronics, Osaka Prefecture University, Sakai, Osaka 593, JAPAN. Key words: YBa2Cu3O7, single crystal, twin boundary, torque magnetometry.
Takekazu Ishida, Kiichi Okuda, and Hidehito Asaoka, "Sequential Vortex States upon Lattice Melting in Untwinned Single-Crystal YBa2Cu3O7." To be published in Phys. Rev. B. Department of Physics and Electronics, Osaka Prefecture University, Sakai, Osaka 593, JAPAN. 74.60.Ge; 74.72.Bk.
R. A. Jennings and C. Greaves, "Electronic and Structural Effects of Substituting Sr (for Ba) and Cr (for Cu) in YBa2Cu3O7-d." Submitted to Physica C. Contact C. Greaves, School of Chemistry, University of Birmingham, Edgbaston, Birmingham B15 2TT, UNITED KINGDOM. Key words: Cr substitution in Y-123, Sr substitution in Y-123, Ca substitution in Y-123. 74.72.Bk; 61.66.Fn.
Jungsoo Kim and D. Coffey, "Single-Particle Properties of a Two- Dimensional Fermi Liquid at Finite Frequencies and Temperatures." Submitted to Phys. Rev. B. Department of Physics, State University of New York, Buffalo, NY 14260; preprint also available at cond- mat@xxx.lanl.gov (#9705065).
J. L. Kissick, C. Greaves, P. P. Edwards, V. M. Cherkashenko, E. Z. Kurmaev, S. Bartkowski, and M. Neumann, "Synthesis, Structure and XPS Characterization of the New Stoichiometric Phase Sr2CuO2F2." Submitted to Phys. Rev. B. Contact C. Greaves, School of Chemistry, University of Birmingham, Edgbaston, Birmingham B15 2TT, UNITED KINGDOM.
Fu-Sui Liu and Jing-yi Wang, "On the Magnitude of the Gap Along Gamma-X in the CuO2 Plane of B2212." To be published in Physica C (in press). Chang Chun Yuan, Building 56, Room 502, Beijing University, Beijing 100871, PEOPLE'S REPUBLIC OF CHINA. 74.20.Mn; 74.25.Dw.
M. Machida, T. Koyama, and M. Tachiki, "Instability of the Longitudinal Plasma Oscillations and Intrinsic ac Josephson Effects in Josephson Coupled High-Tc Superconductors." Submitted to Phys. Rev. Lett. Center for Promotion of Computational Science and Engineering, Japan Atomic Energy Research Institute, 2-2-54, Nakameguro, Meguro-ku, Tokyo 153, JAPAN; telefax +81 3 5723 2537; e-mail mac@sugar.tokai.jaeri.go.jp. 74.25.Fy; 74.50.+r; 74.80.Dm.
D. Manske, C. T. Rieck, R. Das Sharma, A. Bock, and D. Fay, "Screening of the B_[1g] Raman Response in d-Wave Superconductors." To be published in Phys. Rev. B. Abteilung fuer Theoretische Festkoerperphysik am Institut fuer Angewandte Physik, Universitaet Hamburg, Jungiusstrasse 11, D-20355 Hamburg, GERMANY; telephone +49 40 4123 2914; telefax +49 40 4123 6332; e-mail manske@physnet.uni- hamburg.de. 74.20.-z; 74.25.Nf; 78.30.Er.
H. M. Palmer, C. Greaves, M. Slaski, V. A. Trofimova, Yu M. Yarmoshenko, and E. Z. Kurmaev, "Substitution of SO4^[2-]Anions in La1.85Sr0.15CuO4: Structure and Superconductivity." Submitted to Physica C. Contact C. Greaves, School of Chemistry, University of Birmingham, Edgbaston, Birmingham B15 2TT, UNITED KINGDOM. Key words: sulphate, (La,Sr)2CuO4, x-ray diffraction, XES. 74.72.Bk; 61.66.Fn.
R. Platzer, I. D. Dumkow, D. W. Tom, J. A. Gardner, and J. Tate, "Tetragonal-Orthorhombic Phase Transition in YBaCuO Thin Films Observed by Perturbed Angular Correlation Spectroscopy." Submitted to J. Mater. Res. Department of Physics and Center for Advanced Materials Research, Oregon State University, Corvallis, OR 97331-6507; e-mail tate@physics.orst.edu.
C. Ren, S. Y. Ding, L. Qiu, Y. Ge, X. X. Yao, Y. X. Fu, and C. B. Cai, "The Vortex Liquid and Its Transition to a Solid for YBa2Cu3O7-x." To be published in Physica C (in press). Department of Physics, National Laboratory of Solid State Microstructures and Center for Advanced Studies in Science and Technology of Microstructures, Nanjing University, Nanjing 210093, PEOPLE'S REPUBLIC OF CHINA. 74.60.Ge; 74.72.Bk.
Z. F. Ren, J. Y. Lao, L. P. Guo, J. H. Wang, J. D. Budai, D. K. Christen, A. Goyal, M. Paranthaman, E. D. Specht, and J. R. Thompson, "Epitaxial Film Growth of Tl0.78Bi0.22Sr1.6Ba0.4Ca2Cu3O9 on Rolling Assisted Biaxially Textured Nickel Substrates with YSZ and CeO2 Buffer Layers." To be published in J. Supercond. Materials Synthesis Laboratory, Department of Chemistry and New York State Institute on Superconductivity, State University of New York, Buffalo, NY 14260-3000; telefax (716) 645-6949. Key words: epitaxy, thin film, superconductor, critical current density, RABiTS, buffer layers.
Frederic N. Rounds, "Anomalous Weight Behavior in YBa2Cu3O7 Compounds at Low Temperature." NASA Ames Research Center, MS 233-10, Moffett Field, Mountain View, CA 94305; telephone (415) 604-3304; e-mail frounds@mail.arc.nasa.gov; preprint also available at cond- mat@xxx.lanl.gov (#9705317).
D. P. Scarfe and A. J. Jacobson, "Iodine Intercalcation in the Ionic Conductor SrxBi9-xO(27-x)/2." Preprint #97:049; submitted to Chem. Mater. Contact A. J. Jacobson, 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.
M. D. Sumption and E. W. Collings, "ac Loss and Matrix Resistivity in Multifilamentary HTSC Strands: Anomalously High Apparent Matrix Resistivity and Partial Flux Flow Modified Eddy Current Loss." Submitted to Physica C. Department of Materials Science and Engineering, 477 Watts Hall, Ohio State University, 2041 College Avenue, Columbus, OH 43210-1179; telephone (614) 688-3684; telefax (614) 292- 1537; e-mail mdsumption+@osu.edu. Key words: Bi:2223/Ag, high- temperature superconductor, multifilamentary tape, ac loss, matrix resistivity, eddy current, flux creep, flux flow, logarithmic decay, exponential decay.
Xuefeng Sun, Wenbin Wu, Qianwang Chen, Yunbo Jia, Guien Zhou, Xiao-Guang Li, and Yuheng Zhang, "Growth and Characterization of a New Single Crystal Bi2Sr1.5Pr2.5Cu2Oy." Submitted to J. Crystal Growth. Structure Research Laboratory, University of Science and Technology of China, Academia Sinica, Hefei 230026, PEOPLE'S REPUBLIC OF CHINA.
Xuefeng Sun, Wenbin Wu, Lei Zheng, Xiaoru Zhao, Lei Shi, Guien Zhou, Xiao-Guang Li, and Yuheng Zhang, "Effects of Oxygen-Doping and Structural Distortion on Superconductivity of Bi2Sr2CaCu2Oy Single Crystal." To be published in J. Phys. Condens. Matter. Structure Research Laboratory, University of Science and Technology of China, Academia Sinica, Hefei 230026, PEOPLE'S REPUBLIC OF CHINA.
Giovanni Visentini, Anna Painelli, Alberto Girlando, and Alessandro Fortunelli, "The Dimer Model for kappa-Phase Organic Superconductors." Dipartimento di Chimica Generale ed Inorganica, Chimica Analitica e Chimica Fisica, Universita di Parma, I-43100 Parma, ITALY; telephone +39 521-905445 or -905439; telefax +39 521-905556; e-mail giovanni@prcfx1.chim.unipr.it; preprint also available at cond- mat@xxx.lanl.gov (#9706010). 71.15.Fv; 74.20.Fg; 74.70.Kn; 74.72.-h.
Frank K. Wilhelm, Andrei D. Zaikin, and Herve Courtois, "Coherent Electron Transport in Superconducting-Normal Metallic Films." Submitted to Phys. Rev. Lett. Institut fuer Theoretische Festkoerperphysik, Universitaet Karlsruhe, Engesserstr. 7, Physikhochhaus, D-76128 Karlsruhe, GERMANY; telephone +49 721 608 3370; telefax +49 721 69 81 50; e-mail wilhelm@tfp.physik.uni-karlsruhe.de; Web site http://www.physik.uni-karlsruhe.de/wilhelm/; preprint also available at cond-mat@xxx.lanl.gov (#9705225).
N. K. Wilkin and Henrik Jeldtoft Jensen, "Decoupling and Melting in a Layered Superconductor." School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham B15 2TT, UNITED KINGDOM; telephone +44 121 414 7323; telefax +44 121 414 4719; e-mail nkw@th.ph.bham.ac.uk; preprint also available at cond-mat@xxx.lanl.gov (#9705265). 74.60.-w; 74.25.Dw; 07.05.Tp.
N. K. Wilkin and Henrik Jeldtoft Jensen, "Disorder Driven Destruction of a Phase Transition in a Superconductor." School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham B15 2TT, UNITED KINGDOM; telephone +44 121 414 7323; telefax +44 121 414 4719; e- mail nkw@th.ph.bham.ac.uk; preprint also available at cond- mat@xxx.lanl.gov (#9705271). 74.60.Ge; 64.60.Cn.
N. J. Wu, Y. S. Chen, S. Dordevic, and A. Ignatiev, "Pyroelectric IR Sensor Based on Oxide Heterostructures on Si(100) and LaAIO3(100) Substrates." Preprint #97:048; submitted to the proc. of the Third Int. Conf. on Thin Film Phys. and Applications, Shanghai, People's Republic of China, April 14-17, 1997. 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. Key words: pyroelectrics, heterostructure, photoresponse, infrared, uncooled IR detector.
Cheng-Feng J. Yue, D. Kumar, Rajiv K. Singh, "Fabrication of Ag-Sheathed Bi2Sr2CaCu2Ox Tapes Using a Modified Electrophoretic Deposition Method." To be published in Physica C (in press). Contact Rajiv K. Singh, Department of Materials Science and Engineering, University of Florida, Gainesville, FL 32611; telephone (352) 392-1032; telefax (352) 392-3771; e-mail rsing@mse.ufl.edu.
D. Zanchi and H. J. Schulz, "Weakly Correlated Electrons on a Square Lattice: A Renormalization Group Theory." Submitted to Phys. Rev. Lett. Institut fuer Theoretische Physik der Freien Universitaet Berlin, Arnimallee 14, D-14195 Berlin, GERMANY; e-mail zanchi@physik.fu- berlin.de; preprint also available at cond-mat@xxx.lanl.gov (#9703189). 74.20.Mn; 74.25.Dw; 75.30.Fv.
A. A. Zhukov, G. K. Perkins, J. V. Thomas, A. D. Caplin, H. Kuepfer, and T. Wolf, "Direct Observation of Tilted Vortex Structures Induced by Twin Boundaries in YBa2Cu3Oy Single Crystals." To be published in Phys. Rev. B. Centre for High Temperature Superconductivity, Blackett Laboratory, Imperial College, London SW7 2BZ, UNITED KINGDOM; A. D. Caplin's telephone +44 171 594-7608 or -7603; telefax +44 171 594-7580; e-mail d.caplin@ic.ac.uk.
*Sept. 14 - 18, 1997: Conference on Spectroscopies in Novel Superconductors (SNS '97), Sea Crest Oceanfront Resort and Conference Center, Falmouth, Cape Cod, Mass. Conference sponsored by the College of Arts and Sciences as part of centennial celebration of the founding of Northeastern University. Abstract and registration deadline, July 1, 1997. For further information, contact Phyllis Mitzman, Conference Coordinator, The Barnett Institute, Mugar 341, Northeastern University, Boston, MA 02115; telefax (617) 373-8277; e-mail scs97@ neu.edu; Web site http://www.conf.neu.edu/sns97.
*Oct. 27 - 30, 1997: 10th International Symposium on Superconductivity (ISS'97), Gifu, Japan. Organized by the International Superconductivity Technology Center (ISTEC). Symposium will consist of oral and poster sessions and invited talks in the following fields of superconductivity: physics -- theory, physical properties, and new measurement techniques; chemistry -- new materials and syntheses, substitution, solid-state chemistry, and properties; flux pinning -- mechanism and electromagnetic properties of fluxoids; wires, tapes, and bulk -- solid-state powder ceramics, chemical-solution processing, melting solidification, and chemical-vapor deposition; thin films -- processing, properties, and lithography; device applications -- digital, analog, SQUID, and other electronic devices; system applications -- power, power transportation, magnets, magnetic shields, and other system applications. Proceedings to be published. Official language is English. For further information, contact ISS'97 Secretariat, ISTEC, Eishin Kaihatsu Bldg. 6F, 34-3 Shimbashi 5-chome, Minato-ku, Tokyo 105, Japan; telephone +81 3 3431-4002; telefax +81 3 3431-4044.
*Jan. 6 - 9, 1998: 7th Joint MMM-Intermag Conference, San Francisco, Calif. Conference will include all basic and applied science technology related to magnetism. The technical subject categories are: cooperative phenomena and fundamental magnetic properties, transport properties, computational magnetics and imaging, soft magnetic materials and applications, hard magnetic materials and applications, other materials, artificially structured materials, magnetic recording, and interdisciplinary topics and applications. Invited talks, oral presentations, and poster sessions. Exhibition of services, equipment, and materials. Abstract deadline, July 9, 1997. Proceedings to be published in special issues of J. Appl. Phys. and IEEE Trans. on Mag. For further information, contact Diane Suiters or Amy Landsbaum, Conference Coordinators, 655-15th Street N.W., Suite 300, Washington, DC 20005; telephone (202) 639-5088; telefax (202) 347-6109; e-mail magnetism@courtesy.assoc.com. Technical questions regarding abstracts should be directed to one of the Program Chairs: Alison Chaiken, Mailstop L-350, Lawrence Livermore Laboratory, Livermore, CA 94550, telephone (510) 422-7129, telefax (510) 422-6892, e-mail chaiken@llnl.gov; or Toasz Jagielinski, Eastman Kodak Company, 3985 Sorrento Valley Boulevard, San Diego, CA 92121, telephone (619) 535- 6908, telefax (619) 535-6990, e-mail tmj@kodaksdl.com.
March 18 - 20, 1998: 6th International Symposium on Trends and Applications of Thin Films (TATF98), Regensburg, Germany. Conference is dedicated to new applications of thin films and systems, and their production and analysis. Topics include: 1) Hard, Protective, and Decorative Coatings -- processes, diagnostics/process control, innovative materials, large area and high-rate deposition; 2) Films for Microelectronics and Microsystems -- processing and diagnostics, metallization, multilayers, sensors, surface micromachining, and 3D microstructures; 3) Hot Topics -- materials and characterization, film production and equipment, film properties, micro- and nanostructures, intelligent and self-organizing systems, and bioactive and biocompatible films. For information contact H. Hoffmann, Inst. fuer Experimentelle und Angewandte Physik, Universitaet Regensburg, Universitaetsstrasse 31, D-93040 Regensburg, Germany; telephone +49 941 943 2621; telefax +49 941 943 4544; e-mail horst.hoffmann@physik.uni-regensburg.de.
*March 29 - April 3, 1998: Symposium on Applications of Spectroscopy to Superconducting Materials, 215th Spring National American Chemical Society Meeting, Dallas, Texas. Call for papers. Topics will include oral sessions of optical spectroscopies, photoexcitation spectra, other spectra, and applications. The meeting is not restricted to cuprates and may include studies of organic superconductors, fullerides, heavy fermions, and conventional materials. Proceedings to be published. Abstract deadline, September 1, 1997. Contact E. Faulques, Institut the Materiaux, LPC, 2 rue de la Houssiniere, BP 32229, F-44322 Nantes Cedex 3, France; telephone +33 2 40 373972; telefax +33 2 40 373991; e-mail faulques@cnrs-imn.fr; Web site http://www.acs.org/.
*Postdoctoral position: Applications are invited for a possible one- year postdoc position starting early 1998. Due to constraints of the funding agency, this position is open to.U.S. citizens only. Position requires a Ph.D. degree with proven proficiency in one or more of the following areas: solid-state chemistry of superconductor oxides, borocarbides, single-crystal growth, XRD analyses, magnetic (SQUID or ac susceptibility) and resistivity measurements, and/or neutron diffraction. Candidates expecting to receive Ph.D. shortly may also apply. Basic knowledge of French will be useful. For further details contact R. Suryanarayanan, Laboratoire de Chimie des Solides, Bat. 414, Universite Paris-Sud, F-91405 Orsay, France; telephone +33 1 69 15 47 96; telefax +33 1 69 15 47 97; e-mail suryan@isma.isma.u-psud.fr. *Rerun from June 15 issue with additional information.
Active: ($10-$199) Manuel de Llano/NATO Jack R. Leibowitz Jeffrey T. Fritz Laura H. Greene Robert Hammond Michael L. Norton James S. Schilling John T. McDevitt Richard R. Klemm Richard Westfall Daniel Eppelsheimer Bai-Hao Chen Stanton H. Cushner Marketech International Marc J. Feldman John A. Wilson J. R. Gaines, Jr. Krzysztof Rogacki Ivan K. Schuller Albert Chiang Moyses Kuchnir Theodora Leventouri Wei Jiang Yeh Isidoro Rasines Barry Friedman Christopher Lobb C. Vipulanandan John Markert Frederick D. Becchetti Tom Ebetino John M. Rowell James H. Eraker Phillip Wahlbeck Anonymous Friend 10 James L. Smith Adriana Moreo Elbio Dagotto Keith Johnson T. P. Orlando Robert Hoersch Prasanta K. Misra John Huber Antonello Andreone Thomas H. Zepf Charles P. Poole, Jr. Arthur F. Greene, Jr. R. Neelameggham George J. Valco Wai-Yim Ching CTF Systems Inc Masashi Kawasaki Ennis Ogawa Alexei Abrikosov Robert Cuthill Allen M. Hermann Michael W. Klein Hong-Duen Yang Jayaram Betanabhatla Josef Ashkenazi Kazumi Maki John Graybeal Barbara Levi David R. Nelson Paulo Pureur Huey-Chuen I. Kao Tomoko Goto Gert K. G. Hohenwarter Ernst Helmut Brandt C. J. Van Der Beek Sui-Wai Chan Thomas Lee Elifritz S. K. Remillard Colin E. Gough Baird Brandow Victor J. Emery Torsten Freltoft Martha Greenblatt Chan-Joong Kim Howard A. Blackstead Lars Boerjesson Norio Kobayashi Masayasu Nagoshi Antony Bourdillon Yacine Dalichaouch Hofstra University Valentin Garcia-Vazquez Peter Lindenfeld D. J. Scalapino George Schmiedeshoff Kazumasa Togano SEP Associates Intl. Irene von Lampe Marcel A. R. LeBlanc Wolfgang Gawalek Felix Miranda T. Van Duzer Louis A. Schwartzkopf G. J. Russell A. F. Hebard Steve Pierson M. Tinkham J. E. Schirber Robert J. Gottschall Richard Fye M. S. Islam Nathan Bluzer Simon Foner C. S. Pande Steven M. Anlage James C. Ho Dongzi Liu Fred M. Mueller Ulf Klein Hisashi Sato Robert C. Hansen Youwen Xu David Pines John Tranquada Yanru Ren J. E. Gordon W. W. Warren, Jr. Amar Nath Ray Ellis Karlheinz Schwarz Albert Fuerrer Erik Kvam Henry Makowitz V. Z. Kresin M. Barmawi John Gannon John Dash P. H. Kes Michel Lagues John Kucera Sung-Ik Lee Mark David A. Rosen R. L. Meng C. Morris Prem Vaishnava John Miller, Jr. A. Vera Adalberto Balzarotti Q. Y. Ma Sang Boo Nam Junho Gohng Janis Research Company, Inc. (William R. Shields) Claymore Engineering (Denison W. York) Centre for Supercond. and Electronics Mater., U. of Wollongong (P. N. Mikheenko) Center for Mater. Res. and Anal., U. of Nebraska (D. J. Sellmyer) Mark Goldes (Magnetic Power, Inc.) Lester W. Buechler (Electronic Engravers, Inc.) Victor Pappas (Inforex Corporation) Brown University (James M. Valles, Jr.) Superconductor Week (Aaron Bitterman) Zirmat Corp. (Joseph Wenckus) Superconductive Components Inc. (J. R. Gaines, Jr.) McGill University (Louis Taillefer)Supporting ($200-$499) M. R. Tubbs F. de la Cruz Detlef Brinkmann U. Wisconsin Appl. Supercond. Research Center (David Larbalestier) Intermagnetics General Corp. (Carl H. Rosner) Centre for Supercond. and Electronics Mater., U. of Wollongong (S. X. Dou) Asea Brown Boveri AG (Makan Chen) National Institute of Standards & Technology (A. F. Clark)
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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.
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. 11, #13, July 1, 1997.