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 David C. Johnston, Professor of Physics at Iowa State University and Senior Physicist at the Ames Laboratory.

Vortices: Theory

Characteristics of first-order vortex lattice melting are studied theoretically by Dodgson (ETH Hoenggerberg) et al. They derive expressions for the jumps in entropy and magnetization at this transition, accounting for the temperature dependence of the Landau parameters and the proper shape of the melting line. The results agree well with experiments on YBa2Cu3O7-d and Bi2Sr2CaCu2O8.

Another calculation of the entropy jump at the melting (or sublimation) transition is reported by Rae (U. Birmingham) et al. They find that the total change in entropy associated with the transition is over 4 k_B per flux-line per CuO layer, significantly larger than 1.5 k_B per flux-line per CuO layer near Tc previously calculated. They show that the major portion of this entropy can be attributed to the cores of the extra flux lines formed in the transition.

The low-lying excitations around a single vortex in a d-wave superconductor are calculated by Morita (U. Tokyo) et al., using a full quantum-mechanical treatment of the Bogoliubov-de Gennes equation for a single vortex. They find low-energy states extended in four diagonal directions, which have no counterpart in a vortex of an s-wave superconductor. The four-fold symmetry is due to a quantum effect which is enhanced when p_F[xi] is small, where p_F is the Fermi momentum and xi is the superconducting coherence length. For p_F[xi] ~ 1, they find a peak in the density of states with a large energy gap, due to the formation of the lowest bound states.

A preprint by Gorokhov and Blatter (ETH Hoenggerberg) describes calculations of the decay of metastable states. The decay rate at high temperatures is determined by thermal activation, whereas at low temperatures quantum tunneling becomes relevant. The transition between the two regimes can be either first-order like or smooth. The authors predict that the transition associated with depinning of vortices from columnar defects in high-Tc superconductors should be first-order and suggest that this transition should be sought experimentally. However, they caution that the transition temperature would be smeared out if the defects have different radii, but that lithographic techniques might be able to produce defects with identical radii which would ameliorate this problem.

Vortices: Experiment

Evidence for coherent modes of moving Josephson vortices in single- crystal Bi2Sr2CaCu2Ox is reported by Lee et al. (Argonne). They carried out measurements of the c-axis current-voltage (I-V) relationship exhibited in mesas patterned on the surface of the crystals; the applied magnetic field was parallel to the CuO2 layers. The vortex flow I-V curves exhibit a sharp upturn and multiple branches as the current is ramped up and down at fixed magnetic field and temperature.

The pinning effects of arrays of magnetic dots on Nb films are described in a preprint by Martin et al. (UCSD). Triangular and square lattices of magnetic Ni dots were fabricated using electron beam lithography, with dot radii of 100-200 nm and spacings of 400-600 nm. The resistivity versus magnetic field curves show a series of sharp minima at temperatures close to Tc, at field values which are integral multiples of the matching field of the array. Control experiments using nonmagnetic Ag dots did not show this effect, indicating that the commensurability effects using Ni dots are magnetic in origin.

Measurements of the dependence on magnetic field and array size of the resistive transition of Josephson junction arrays with long-range interaction are reported by Shea and Tinkham (Harvard). In these arrays, every wire has a large number (9 or 18) of nearest-neighbors. The data are found to agree well with a mean-field calculation, which predicts that Tc (the temperature below which the array exhibits macroscopic phase coherence) shows very strong commensurability effects and scales with array size.

Critical-current-density Jc enhancements of the highest-Tc Tl- and Hg- based cuprate superconductors using 0.8 GeV proton irradiation are reported by Thompson (Oak Ridge) et al. The protons cause heavy constituent nuclei (Tl, Hg, Bi) to fission, which generates randomly oriented columnar defects, leading to significant enhancements in Jc. Bulk materials and thin films were investigated, irradiated with or without Pb or Au "amplifier foil" overlayers which increase the number of fission fragments.

Pseudogaps, Bose-Einstein Condensation

The temperature and doping dependences of the c-polarized infrared active optical phonons of high-quality single crystals of La2-xSrxCuO4 (x = 0.1, 0.12, 0.15, 0.18, 0.2) between 10 and 300 K are studied by Henn (MPI Stuttgart) et al. using far infrared ellipsometry, which allowed direct determinations of the dielectric function. They did not observe any anomalies of the phonon parameters which could be related to the opening of a superconducting gap, a spin gap or any other kind of pseudogap in the normal state of the underdoped compounds.

On the other hand, Startseva (McMaster U.) et al. have measured the ab- plane optical spectra of two single crystals of La2-xSrxCuO4 (x = 0.14, 0.22). They observe a gap-like suppression of the effective scattering rate below 700 cm^[-1] in both crystals. The authors conclude that the optical data in the far-infrared region for both the underdoped and overdoped crystals show clear evidence of a pseudogap at temperatures exceeding 300 K.

The problem of fermions in two dimensions with an attractive interaction in the singlet d-wave channel of arbitrary strength is considered by Stintzing and Zwerger (Munich). A statistical Ginzburg-Landau theory is derived which describes the smooth crossover from a weak-coupling BCS superconductor to a condensate of composite bosons. Comparison of the theory with experimental data for YBa2Cu3O7-d and Bi2Sr2Ca2Cu3O10 indicate that the optimally doped materials are on the weak coupling side of the crossover to a Bose regime, i.e., that there is a negligible density of preformed pairs above Tc. A discussion of open questions concerning improvements in the theory and the applicability of the theory to high-Tc compounds is given.

A relativistic spin-fermion model for the cuprates, in which both the charge and spin degrees of freedom are treated dynamically, is given by Alonso (U. Zaragoza, Spain) et al. The model accounts for the various phases of the cuprates and their properties in the low (antiferromagnetism), intermediate (high-Tc superconductivity) and overdoped (Fermi liquid) regimes. High-Tc superconductivity is understood to occur through Bose-Einstein condensation of bound charge pairs. The model predicts that superconductivity is unlikely to occur in materials with spin S > 1/2, and raises the possibility of re-entrant superconductivity. The authors believe the model to be applicable to a wider class of materials with strong magnetism-induced correlations; in particular, they suggest that it may account for giant magnetoresistance in the manganese oxide perovskites.

Doped Three-Leg Ladders

Lightly-doped three-leg ladders are studied by Rice (ETH-Hoenggerberg) et al. and analogies are made with the underdoped layered cuprates. Numerical calculations for a t-J model show that the initial phase of the three-leg ladder upon hole doping has two components -- a conducting Luttinger liquid in the odd-parity channel, coexisting with an insulating (undoped) spin-liquid phase in the two even-parity channels; this phase violates the Luttinger theorem. A mean field approximation is derived which indicates hole pairing in the odd-parity channel at arbitrarily small doping. At higher doping, the authors propose that a quantum phase transition occurs as holes enter the even-parity channels, resulting in a Luther-Emery liquid with hole pairing with essentially d- wave character.

Superconducting Order Parameter Symmetry

As reported by Panagopoulos (U. Cambridge) et al., the anisotropic magnetic penetration depth lambda was measured using ac magnetic susceptibility measurements (0.3-3 G rms, 333 Hz) down to 1.2 K on grain-aligned powders of tetragonal HgBa2CuO4+d (Hg1201, Tc^[onset] = 93 K) and HgBa2Ca2Cu3O8+d (Hg1223, Tc^[onset] = 134.5 K). At low temperatures, lambda_[ab] varies as T in both Hg1201 and Hg1223, whereas lambda_c varies as T^5 and T^2, respectively. For orthorhombic YBa2Cu3O7-d with d = 0 (Tc^[onset] = 92 K) and d = 0.43 (Tc^[onset] = 55 K), the authors find that lambda_c varies as T and T^2, respectively. The results are discussed in terms of d_[x^2-y^2]-wave superconducting order parameter symmetry.

The magnetic interference pattern in a clean s-wave--normal metal--d- wave superconductor (SND) junction is calculated by Zagoskin (UBC). The shape and periodicity of the interference pattern depend on the orientation of the d-wave superconductor with respect to the normal- superconducting interface. The author suggests that the orientation- dependent interference pattern in SND junctions could be a powerful probe of the order parameter symmetry in cuprates.

The response of a weak-coupling two-dimensional d_[x^2-y^2]-wave superconductor to a magnetic field B that couples only to the spins of the electrons is studied by Yang (Princeton) and Sondhi (Princeton and UCSB). They find that in contrast to s-wave superconductors, the d_[x^2-y^2] state is modified even at small B, with the nodes of the gap widening into normal, spin polarized, elliptical pockets at the Fermi surface. Predictions for the temperature T and B variations of the specific heat, thermal conductivity, magnetization and tunneling conductance are given. The phase diagram in the B-T plane is discussed, which includes a Fulde-Ferrell-Larkin-Ovchinnikov state at high fields in which the Cooper pairs have a finite center of mass momentum.

The superconducting pairing symmetry in single-crystal Bi2Sr2CaCu2O8+x has been probed using break junction tunneling measurements by Hancotte (Brussels) et al. The differential conductance curves were analyzed with s-, d-, and s+d-wave models. Evidence for predominance of the d- wave component was reported.

Normal-State Transport

Phenomenological interpretations within both Fermi-liquid and non-Fermi- liquid models of the ac Hall effect in the normal state of YBa2Cu3O7 are considered by Zheleznyak (U. Maryland) et al. In the Fermi-liquid analysis, the electron relaxation rate is assumed to vary over the Fermi surface. The non-Fermi-liquid models are the two-dimensional Luttinger liquid and the charge-conjugation-symmetry models. The authors find that the existing experimental data can be adequately fitted by all of these models. They suggest that measurements of the frequency dependence of the ac Hall effect at different temperatures may allow the applicability of the different models to be discriminated.

Materials

New layered transition metal oxysulfides are reported in two preprints by Zhu and Hor (U. Houston). Sr2Cu2MO2S2 (M = Mn, Zn) contain alternating square planar MO2 sheets and anti-PbO type Cu2S2 layers. Both compounds are semiconducting, and the compound with M = Mn exhibits antiferromagnetic (AF) ordering at about 29 K. Other new compounds containing Cu2S2 layers are Sr3Cu2Fe2O5S2 and Sr2CuMO3S (M = Cr, Fe, In). Sr2CuCrO3S shows AF ordering at 60 K.

The effect of Re substitution on the defect structures and superconducting properties of (Hg1-xRex)Ba2Can-1CunO2n+2+d (n = 2, 3, 4) is investigated by Chmaissem et al. (Argonne) using neutron powder diffraction, ac susceptibility and magnetization measurements. The as- prepared samples showed Tc = 108 K, 132 K, and 122 K for n = 2, 3, and 4, respectively. Re atoms substitute at the Hg site and alter the defect structure of the host layer by pulling in four new oxygen atoms to form an octahedron around Re.

Electrochemical intercalation of oxygen in Pr2NiO4+d and related oxides is studied by Jacobson and Bhavaraju (U. Houston). They report the ambient temperature phase diagram of Pr2NiO4+d for 0 <= d <= 0.165 and verify it by structural analysis of seven compositions synthesized electrochemically. They find that the phase diagram is in good agreement with literature data obtained for single-crystal samples prepared by high-temperature annealing methods. The electrochemical data for Pr2NiO4+d are found to be closely similar to those previously reported for Nd2NiO4+d but differ substantially from results for La2NiO4+d. The thermodynamics of oxidation of the Ln2NiO4+d phases correlates with the change in size of the rare earth cation.

Incommensurate modulations such as seen along the b-axis of the Bi cuprates can take two limiting forms: a sinusoidal modulation or a periodic succession of solitons (discommensurations) between commensurate regions. In a preprint by Clin (U. Picardie Jules Verne) et al., discommensuration patterns in samples of nominal composition Bi2Sr2CaCu2O8 and Bi1.6Pb0.4Sr2CaCu2O8 were found from transmission electron microscopy measurements. High resolution evidence for the translation slip across a discommensuration wall is obtained for the first time. The authors show that a wide range of "latent" commensurate periods determine the characteristics of the walls.

In a related paper, Miles (New South Wales) et al. report that neutron- diffraction studies of the diffuse features around main and satellite reflections of high-quality single crystals of Bi2Sr2CaCu2O8+x show that extra "forbidden" reflections and other anomalous diffuse features are a function of crystal quality and not part of the inherent crystallographic structure.

Films

The first successful fabrication of Tl2Ba2CaCu2Oy superconducting thin films on polycrystalline Al2O3 substrates using yttria-stabilized- zirconia buffer layers is reported in a preprint by Xiong et al. (U. Arkansas). The films were shiny, highly c-axis oriented, and strongly in-plane textured, with a zero resistance Tc up to 108 K and with a critical current density of ~ 10^5 A/cm^2 at 77 K.

A transition from 2D nucleation to spiral growth in pulsed-laser- deposited YBa2Cu3O7-d films is reported by Dam et al. (Free U., Amsterdam). The growth mode was monitored using scanning probe microscopy. By increasing the background oxygen pressure, the generally observed 2D nucleation and growth mode transforms into a spiral growth mode. On the other hand, keeping the oxygen pressure at increased levels and reducing the target-substrate distance causes the growth spirals to disappear and 2D nucleation and growth to again become the dominant growth mode. The authors attribute the growth mode transition to a change in surface diffusivity of ~2 orders of magnitude.

Other Activities

Femtosecond spectroscopic studies of photodoping effects in insulating YBa2Cu3O6+x and Nd2CuO4 thin films are reported by Matsuda (Nagoya U.) et al. The spectral features of the absorption change are in good agreement with the change upon chemical doping, indicating that the electronic structures in the CuO2 planes are drastically changed by the femtosecond laser pulses.

In a preprint by Terashima (N.R.I.M., Tsukuba) et al., de Haas-van Alphen effect measurements at temperatures down to 0.05 K are reported on single-crystal YNi2B2C [H_[c2](T = 0) = 8.8 T] in the vortex state down to a field of 2 T. The oscillation amplitude is strongly suppressed in a field region immediately below H_[c2] but recovers at lower fields. The observed amplitude at low fields is found to be much larger than theoretical predictions based on the literature value of the superconducting gap. The authors infer that the superconducting gap on the observed part of the Fermi surface is much smaller than on other parts.

The mixed-state specific heat of Nb0.77Zr0.23 vs. magnetic field was measured by Mirmelstein et al. (U. Geneva) in order to document the behavior of the mean-field mixed-state specific heat of an isotropic, strongly type-II superconductor and to provide a basis for comparison with the high-Tc superconductors. The upper critical field H_[c2](T), thermodynamic critical field H_c(T), Ginzburg parameter kappa(T) and electronic coefficient gamma(B, T-->0) are derived and found to be in agreement with the GLAG theory in the dirty limit.

There is a growing need to develop nondestructive microscopy techniques to quantitatively measure the microwave properties of materials on a length scale much less than the free-space wavelength. Steinhauer et al. (U. Maryland) describe the design, construction and operating characteristics of a scanning near-field microwave microscope which can be used to measure sample surface sheet resistance at microwave frequencies with a spatial resolution of ~100 micrometers.

Overviews

Processing for Tl-based cuprate thick films on wire and tape is reviewed by Bhattacharya (NREL) et al. The merits of such materials as a conductor for near-term use in electric power applications currently under development such as in transformers and transmission cables are discussed.

Characteristics and requirements for current leads for cryogenic applications are reviewed by Herrmann (Alcatel, France). Most currently envisioned applications, apart from electronic devices, are for superconducting magnets requiring moderate to very high currents. Topics considered include cooling and important materials parameters, design concepts, cryogenic heat load and stability aspects. A brief discussion of the design criteria for metallic ac current leads is given. Another section is devoted to current leads using high- temperature superconductors (HTS) and design concepts of hybrid metallic-HTS current leads for dc and 50/60 Hz ac applications, including discussion of cryogenic heat load and stability aspects. Test results of such hybrid leads are compared to the performances of all- normal-metal current leads.

Contributed by D. C. Johnston

Contents: Technology News is on page 5; Preprints begin on page 5; Coming Events begin on page 10; and FYI is on page 11.

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

TECHNOLOGY NEWS (Also see Applications section of Nota Bene.)

This section describes progress in manufacturing, product development, and technology transfer in the high-Tc superconductivity field. Please send your contributions (product development information, news regarding technology transfer efforts, or any information you would like to share about your corporation or laboratory) to the editor.

The launch of the first product in its superconducting-magnetic-energy- storage (SMES) product line was announced by American Superconductor Corporation (ASC) with the introduction of the PQ DC[TM], a low- temperature superconductor (LTS) commercial SMES device. The device was developed by Superconductivity, Inc. (SI), a wholly owned subsidiary of American Superconductor. The PQ DC[TM] is designed to effectively eliminate the costly impacts of momentary voltage sags and power outages, and the company believes the market opportunity for SMES-based power quality solutions is greater than $500 million per year. Extensive field testing of SI's first PQ DC[TM] began on a chemical mixing unit in May 1993 at Cyanco, a large industrial manufacturer of cyanide, and a larger system was installed at Tinker Air Force Base in June 1996 as part of the protection scheme for its Defense Megacenter's computers. This unit has absorbed many momentary voltage dips and outages over the last year and a second PQ DC[TM] unit was shipped to Tinker AFB recently.

The focus of ASC's SMES product line is on power levels of 1 MVA up to 10 MVA, the power range of prime interest to industrial users of electric power. These products provide instantaneous voltage boosts or outage protection to ensure continuous operation of machinery and data storage. The product is designed to boost voltages in drive systems, such as those used in pumps, fans, mixing vats, continuous processing lines, and others that incorporate dc drives. It is also used to increase the reliability and extend the life of battery back up systems, which provide dc power for uninterruptable power supplies (UPS) employed in large data systems. The next step in product improvement and cost reduction for the PQ DC[TM] is to incorporate ASC's commercial HTS CryoSaver[TM] current leads into it, which is planned for this fiscal year.

The company also anticipates the next product in the LTS-SMES line, the PQ VR[TM], to complete successful beta testing this fiscal year and be available commercially in the next fiscal year. The PQ VR[TM] systems are designed to handle ac applications and provide significant quantities of power in order to handle substantial sags in voltage on the power lines into industrial manufacturing operations. For further information contact Ramesh Ratan, American Superconductor Corporation, Two Technology Drive, Westborough, MA 01581; telephone (508) 836-4200; telefax (508) 836-4248.

Contributed by Sreeparna Mitra

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

J. L. Alonso, Ph. Boucaud, V. Martin-Mayor, and A. J. van der Sijs, "A Model for the Doped Copper Oxide Compounds." Technical Report TR-97-05. Library, CSCS/SCSC, via Cantonale, CH-6928 Manno, SWITZERLAND; telephone +41 91 610 8211; telefax +41 91 610 8282; e-mail library@cscs.ch; Web site http://www.cscs.ch/official/publications.html; preprint also available at cond-mat@xxx.lanl.gov (#9706022). 74.20.-z; 75.10.Jm; 71.27.+a; 74.25.Dw.

Athanassios Bardas and Dmitri V. Averin, "Electron Transport in Mesoscopic Disordered SNS Junctions." Department of Physics, State University of New York at Stony Brook, Stony Brook, NY 11794-3800; telephone (516) 216-5019; e-mail tbardas@insti.physics.sunysb.edu; Web site http://insti.physics.sunysb.edu/~tbardas/; preprint also available at cond-mat@xxx.lanl.gov (#9706087). 74.50.+r; 74.80.Fp; 73.50.Lw.

R. N. Bhattacharya, R. D. Blaugher, A. Natarajan, C. M. Carlson, P. A. Parilla, D. S. Ginley, M. Paranthaman, A. Goyal, and D. M. Kroeger, "Thick-Film Processing for Tl-Oxide Wire and Tape." To be published in Physica C. National Renewable Energy Laboratory, Golden, CO 80401. Key words: thick-film, electrodeposition, textured substrates, Tl oxides.

Sujeet Chaudhary, Subhash C. Kashyap, D. K. Pandya, and V. N. Kulkarni, "Atomic Disorder in Low Pressure rf-Sputtered YBCO Superconducting Thin Films." To be published in Physica C (in press). Contact Subhash C. Kashyap, Thin Film Laboratory, Department of Physics, Indian Institute of Technology, Delhi, New Delhi 110 016, INDIA; telephone +91 11-6857654 or -666979, ext. 7421; telefax +91 11-6862037; e-mail skashyap@physics.iitd.ernet.in. Key words: rf-magnetron sputtering, thin films, high-temperature superconductivity, atomic disorder. 74.76.Bz; 74.72.Bk.

C. L. Chen, Y. Cao, Z. J. Huang, Q. D. Jiang, Z. H. Zhang, Y. Y. Sun, W. N. Kang, L. M. Dezaneti, W. K. Chu, and C. W. Chu, "The Growth and Characterization of Epitaxial SrRuO3 Thin Films on (001) SrTiO3." Preprint #97:050; to be published in Appl. Phys. Lett. Texas Center for Superconductivity, University of Houston, Houston, TX 77204-5932; telephone (713) 743-8200; telefax (713) 743-8201; e-mail preprints@www.tcs.uh.edu.

O. Chmaissem, P. Guptasarma, U. Welp, D. G. Hinks, and J. D. Jorgensen, "Effect of Re Substitution on the Defect Structure and Superconducting Properties of (Hg1-xRex)Ba2Can-1CunO2n+2+d (n=2,3,4)." Submitted to Physica C. Contact Janice Coble, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439; telefax (708) 252-9595; e-mail janice_coble@qmgate.anl.gov.

M. Clin, K. El Boussiri, J. Henocque, J. Schneck, J. C. Toledano, F. Portemer, and D. Morin, "Discommensuration Patterns in the Bi-Sr-Ca-Cu-O High Tc Superconductors." To be published in Physica C (in press). Laboratoire de Physique de la Matiere Condensee, Universite de Picardie Jules Verne, Faculte des Sciences, 33 rue Saint Leu, F-80039 Amiens Cedex 01, FRANCE; telephone +33 32282 7664; telefax +33 32282 7891. Key words: discommensurations, Bi-Sr-Ca-Cu-O superconductors.

B. Dam, J. H. Rector, J.M. Huijbregtse, and R. Griessen, "The Transition from 2D-Nucleation to Spiral Growth in Pulsed Laser Deposited YBa2Cu3O7- d Films." Institute COMPAS and Faculty of Physics and Astronomy, Free University, De Boelelaan 1081, NL-1081 HV Amsterdam, THE NETHERLANDS; e- mail dam@nat.vu.nl. Key words: growth mechanisms, surface diffusion, pulsed-laser deposition, spiral growth.

Matthew J.W. Dodgson, Vadim B. Geshkenbein, Henrik Nordborg, and Gianni Blatter, "Characteristics of First-Order Vortex Lattice Melting: Jumps in Entropy and Magnetization." Preprint #ETH-TH/97-15. Theoretische Physik, ETH-Hoenggerberg, CH-8093 Zurich, SWITZERLAND; e-mail mattd@itp.phys.ethz.ch; preprint also available at cond-mat@xxx.lanl.gov (#9705220). 74.60.Ec; 74.60.Ge.

Patricia Dolez, Julian Cave, Dag Willen, Wen Zhu, and Marcel Aubin, "Improvements and Validation of the Null Calorimetric Method for ac Loss Measurements in Superconductors." Submitted to Cryogenics. Contact Marcel Aubin, Department of Physics, Universite de Sherbrooke, Sherbrooke, Quebec, CANADA J1K 2R1; e-mail maubin@pauli.physique.usherb.ca. Key words: ac losses, calorimetric, superconductors.

T. B. Doyle, R. Labusch, and R. A. Doyle, "Quasi-Static Magnetic Behavior of a Disc-Shaped Type II Superconductor." Submitted to Physica C. Department of Physics, University of Natal, Durban 4001, SOUTH AFRICA; R. A. Doyle's telephone in the United Kingdom +44 1223-337072 or +44 1223-338948; telefax +44 1223-337074; e-mail rad1005@hermes.cam.ac.uk or rad1005@cus.cam.ac.uk. 74.60.Ec; 74.60.Ge; 74.60.Jg.

R. M. Fye, "Hole-Pair Symmetry and Excitations in the Strong-Coupling Extended t-J_z Model." Submitted to Phys. Rev. Lett. Department of Physics and Astronomy, University of New Mexico, Albuquerque, NM 87131.

F. Galante, E. Rodriguez, J. Fontcuberta, and X. Obradors, "Observation of a Novel Vortex-Liquid State in YBa2Cu3O7:Y2BaCuO5." Contact E. Rodriguez, Lab. de Bajas Temperaturas, Pab. I, Ciudad Universitaria, 1428 Buenos Aires, ARGENTINA; e-mail eduardo@df.uba.ar.

D. A. Gorokhov and G. Blatter, "Decay of Metastable States: Sharp Transition from Quantum to Classical Behavior." Preprint #ETH-TH/97-12. Theoretische Physik, ETH-Hoenggerberg, CH-8093 Zurich, SWITZERLAND. 64.60.My; 74.50.+r; 74.60.Ge.

Tomoko Goto, Tadanori Miura, and Tatsuhiro Hayashi, "Oxygen Controlled Melt Growth of Filamentary Nd123 Oxide Superconductor by Solution Spinning Method." To be published in Jpn. J. Appl. Phys. Department of Materials Science and Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466, JAPAN; e-mail zwgoto@mse.nitech.ac.jp. Key words: filamentary, Nd-Ba-Cu-O, oxygen-controlled melt growth, solution spinning, critical current density.

H. Hancotte, D. N. Davydov, R. Deltour, A.G.M. Jansen, and P. Wyder, "Break Junction Measurements on Bi2Sr2Ca1Cu2O8+x Single Crystals: Analysis of the Superconducting Pairing Symmetry." To be published in Physica C (in press). Contact R. Deltour, Universite Libre de Bruxelles, Service de Physique des Solides, CP233, Bd. du Triomphe, B- 1050 Bruxelles, BELGIUM; telefax +32 2 650 5916; e-mail rdeltour@ulb.ac.be. Key words: high-Tc superconductors, tunneling effect, d wave. 74.50.+r; 74.72.Hs; 74.80.Fp.

R. Henn, A. Wittlin, M. Cardona, and S. Uchida, "Dynamics of the c- Polarized Infrared Active Modes in La2-xSrxCuO4." To be published in Phys. Rev. B. Max-Planck-Institut fuer Festkoerperforschung; Heisenbergstrasse 1, D-70563 Stuttgart, GERMANY; telephone +49 711 689 1728; telefax +49 711 689 1712; e-mail henn@cardix.mpi-stuttgart.mpg.de. 74.72.Dn; 78.30.-j; 74.25.Kc.

P. F. Herrmann, "Current Leads for Cryogenic Applications." To be published in the Handbook of Applied Superconductivity (IOP Publishing). Materials and Electrical Engineering Unit, Alcatel Alsthom Recherche, F- 91460 Marcoussis, FRANCE.

M. W. Hosking, B. A. Tonkin, A. E. Centeno, A. P. Bramley, A. P. Jenkins, and C.R.M. Grovenor, "Power Dependence and Group Delay Comparison of High-Tc Superconducting Microwave Filters." Presented at the Int. Wireless and Telecomm. Symp. (IWTS'97), Shah Alam, Malaysia, May 14-16, 1997. Dept. of Electrical and Electronic Engineering, University of Portsmouth, Anglesea Road, Portsmouth, PO1 4QH, UNITED KINGDOM; B. A. Tonkin's telephone +44 1705 842638; telefax +44 1705 842564; e-mail tonkinb@port.ac.uk. Key words: high-temperature superconductors, microstrip filters, penetration depth, thin film GdBa2Cu3O7-x, thin film Tl2Ba2Ca2Cu3Ox.

Sun-Li Huang, M. R. Koblischka, T. H. Johansen, H. Bratsberg, and K. Fossheim, "Flux Pinning and Grain Coupling in Bi2Sr2CaCu2O8+d Ceramics: Magneto-Optical Investigations." Presented at the 3rd European Conf. on Appl. Supercond. (EUCAS'97), Veldhoven, The Netherlands, June 30-July 3, 1997. Department of Physics, NTNU Trondheim, Sem Saelandsvei 9, N-7034 Trondheim, NORWAY; telefax +47 73 59 3695; e-mail sunlih@phys.ntnu.no.

Takekazu Ishida, Takeshi Mikayama, and Kiichi Okuda, "Search for a d- Wave Chiral-Glass Transition in Granular High-Tc Superconductor (Sr0.7Ca0.3)0.95CuO2-x." To be published in J. Phys. Soc. Jpn. Department of Physics and Electronics, Osaka Prefecture University, Sakai, Osaka 593; JAPAN; e-mail ishida@center.osakafu-u.ac.jp. Key words: chiral-glass transition, d-wave superconductivity, infinite- layer superconductor, nonlinear susceptibility, harmonic susceptibility.

A. J. Jacobson and S. Bhavaraju, "Electrochemical Intercalation of Oxygen in Pr2NiO4+d and Related Oxides." Preprint #97:057; submitted to the Proc. of the 190th Meeting of the Electrochem. Soc., San Antonio, TX, Oct. 6-11, 1996. 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.

Maarit Karppinen and Hisao Yamauchi, "Metal Valences and Hole-Doping Routes in Tl- and Hg-Based Superconducting Cuprates." To be published in J. Supercond.: Proc. of the Int. Workshop on Tl- and Hg-Based Supercond. Mater., Cambridge, United Kingdom, May 25-28, 1997. Materials and Structures Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226, JAPAN; Hisao Yamauchi's telephone +81 45-924 5315; telefax +81 45-921 6953 or -924 5360; e-mail yamauchi@materia.titech.ac.jp. Key words: Tl- and Hg-superconductors, oxygen content, Cu-valence, hole-doping mechanism.

Yong-Jihn Kim and K. J. Chang, "Weak Localization Effect in Superconductors." Department of Physics, Korea Advanced Institute of Science and Technology, Taejon 305-701, KOREA; telefax +82 42 869 2510; e-mail yjkim@julie.kaist.ac.kr; preprint also available at cond- mat@xxx.lanl.gov (#9706032). 74.20.-z; 74.40.+k.

M. R. Koblischka, "Pinning in Bulk High-Tc Superconductors." Presented at the 3rd European Conf. on Appl. Supercond. (EUCAS'97), Veldhoven, The Netherlands, June 30-July 3, 1997. Department of Physics, University of Oslo, P.O. Box 1048, Blindern, N-0316 Oslo, NORWAY; telefax +47 22 85 6422; e-mail m.r.koblischka@fys.uio.no.

M. R. Koblischka, T. H. Johansen, and H. Bratsberg, "Magneto-Optic Visualization of Flux Penetration in Bi-2223 Tapes after Bending." Presented at the 3rd European Conf. on Appl. Supercond. (EUCAS'97), Veldhoven, The Netherlands, June 30-July 3, 1997. Department of Physics, University of Oslo, P.O. Box 1048, Blindern, N-0316 Oslo, NORWAY; telefax +47 22 85 6422; e-mail m.r.koblischka@fys.uio.no.

M. R. Koblischka, A.J.J. van Dalen, T. Higuchi, K. Sawada, H. Kojo, S. I. Yoo, and M. Murakami, "Scaling of Current Densities and Pinning Forces in NdBa2Cu3O7-d." Presented at the 3rd European Conf. on Appl. Supercond. (EUCAS'97), Veldhoven, The Netherlands, June 30-July 3, 1997. Department of Physics, University of Oslo, P.O. Box 1048, Blindern, N- 0316 Oslo, NORWAY; telefax +47 22 85 6422; e-mail m.r.koblischka@fys.uio.no.

N. B. Kopnin and G. E. Volovik, "Rotating Vortex Core: An Instrument for Detecting the Core Excitations." Submitted to Phys. Rev. B. Landau Institute for Theoretical Physics, 117334 Moscow, RUSSIA; G. E. Volovik's e-mail volovik@boojum.hut.fi; preprint also available at cond- mat@xxx.lanl.gov (#9706082). 67.57.Fg; 74.25.Jb; 04.70.Dy; 11.27.+d.

M. L. Kulic, A. I. Buzdin, and L. N. Bulaevskii, "Theory of Interlay of Nuclear Magnetism and Superconductivity in AuIn2." Max-Planck-Institut fuer Festkoerperforschung, Heisenbergstrasse 1, W-70569 Stuttgart, GERMANY; e-mail kulic@audrey.mpi-stuttgart.mpg.de.

R. Labusch and T. B. Doyle, "Macroscopic Equations for the Description of the Quasi-Static Magnetic Behavior of a Type II Superconductor of Arbitrary Shape." Submitted to Physica C. Institut fuer Angewandte Physik, Der Technischen Universitaet Clausthal, D-3992 Clausthal- Zellerfeld, GERMANY; R. A. Doyle's telephone in the United Kingdom +44 1223-337072 or +44 1223-338948; telefax +44 1223-337074; e-mail rad1005@hermes.cam.ac.uk or rad1005@cus.cam.ac.uk. 74.30.Ge.

J. U. Lee, P. Guptasarma, D. Hornbaker, A. El-Kortas, D. Hinks, and K. E. Gray, "Observation of Coherent Modes of Josephson Vortices in Bi2Sr2CaCu2Ox." To be published in Appl. Phys. Lett. Contact Janice Coble, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439; telefax (708) 252-9595; e-mail janice_coble@qmgate.anl.gov.

S. Li, Q. Y. Hu, H. K. Liu, S. X. Dou, and W. Gao, "The Grain Alignment of Bi2223, Bi2212 and Bi2223+Bi2212 Phases in Mechanical Deformation and Annealing Processes." To be published in Physica C (in press). Contact W. Gao, Department of Chemical and Materials Engineering, University of Auckland, Auckland, NEW ZEALAND.

J. I. Martin, M. Velez, J. Nogues, A. Hoffmann, Y. Jaccard, and I. K. Schuller, "Pinning Effects by Arrays of Magnetic Dots on Niobium Film." To be published in J. Magn. Magn. Mater.: Proc. of the Int. Conf. on Magnetism (ICM '97), Cairns, Australia, July 27-Aug. 1, 1997. Contact I. K. Schuller, Department of Physics, University of California at San Diego, La Jolla, CA 92093-0319; telefax (619) 534-0173; e-mail ischuller@ucsd.edu. Key words: small particles, flux pinning, vortex dynamics, thin films, niobium.

K. Matsuda, M. Ichida, A. Nakamura, K. Kawamoto, T. Nabatame, and I. Hirabayashi, "Femtosecond Spectroscopic Studies of Photodoping Effects in Insulating YBa2Cu3O6+x and Nd2CuO4 Thin Films." To be published in Physica C (in press). Contact A. Nakamura, Department of Applied Physics, Faculty of Engineering and Center for Integrated Research in Science and Engineering, Nagoya University, Chikusa-ku, Nagoya 464-01, JAPAN; telefax +81 52 789 5316; e-mail nakamura@nuap.nagoya-u.ac.jp. Key words: optical absorption, electronic structure, thin films.

P. A. Miles, S. J. Kennedy, G. J. McIntyre, G. D. Gu, G. J. Russell, and N. Koshizuka, "Diffuse Features in Neutron Diffraction Studies of High Quality Bi-2212 Single Crystals." To be published in Physica C (in press). Contact G. J. Russell, Advanced Electronic Materials Group, School of Physics, University of NSW, Sydney, NSW 2052, AUSTRALIA; telephone +61 2 3854542; telefax +61 2 3856060; e-mail g.russell@unsw.edu.au.

A. Mirmelstein, A. Junod, E. Walker, B. Revaz, J.-Y. Genoud, and G. Triscone, "Mixed-State Specific Heat of the Type-II Superconductor Nb0.77Zr0.23 in Magnetic Fields Up to B_[c2]." To be published in J. Supercond. Contact A. Junod, Departement de Physique de la Matiere Condensee, Universite de Geneve, 24 quai Ernest-Ansermet, CH-1211 Geneve 4, SWITZERLAND; telephone +41 22 702 6204; telefax +41 22 702 6869; e- mail alain.junod@physics.unige.ch. Key words: type-II superconductivity, mixed state, specific heat, Nb1-xZrx.

Y. Morita, M. Kohmoto, and K. Maki, "Low-Lying Excitations Around a Single Vortex in a d-Wave Superconductor." Contact M. Kohmoto, Institute for Solid State Physics, University of Tokyo, 7-22-1 Roppongi, Minato-ku, Tokyo 106, JAPAN; e-mail kohmoto@issp.u-tokyo.ac.jp.

A. S. Moskvin, V. A. Korotaev, Yu. D. Panov, and M. A. Sidorov, "Non- Rigid Shell Model and Correlational Mechanism of the Local Pairing." Department of Theoretical Physics, Ural State University, 620083, Lenin Avenue 51, Ekaterinburg, RUSSIA; Yu. D. Panov's e-mail yuri.panov@usu.ru.

A. S. Moskvin, A. S. Ovchinnikov, Yu. D. Panov, and M. A. Sidorov, "Polar Jahn-Teller Centers and Isotope Effect in Copper Oxide High-Tc Superconductors." To be published in Physica C: Proc. of the 5th Int. Conf. on Mater. and Mech. of Supercond. -- High-Temp. Supercond. (M^2S- HTSC V), Beijing, People's Republic of China, Feb. 28-Mar. 4, 1997. Department of Theoretical Physics, Ural State University, 620083, Lenin Avenue 51, Ekaterinburg, RUSSIA; Yu. D. Panov's e-mail yuri.panov@usu.ru; preprint also available at cond-mat@xxx.lanl.gov (#9705306).

Akira Ono, "Superconductivity in Ba2-yY1+yCu3-xGaxOz Annealed at 2 GPa." To be published in Physica C (in press). National Institute for Research in Inorganic Materials, 1-1 Namiki, Tsukuba 305, JAPAN. Key words: Ba2-yY1+yCu3-xGaxOz, EDX analysis, high-pressure synthesis.

C. Panagopoulos, J. R. Cooper, T. Xiang, G. B. Peacock, I. Gameson, and P. P. Edwards, "Probing the Order Parameter and the c-Axis Coupling of High-Tc Cuprates by Penetration Depth Measurements." Interdisciplinary Research Centre in Superconductivity, University of Cambridge, Madingley Road, Cambridge CB3 0HE, UNITED KINGDOM; telephone +44 1223-337076 or -337046; telefax +44 1223-337074; e-mail cp200@hermes.cam.ac.uk. 74.72.Gr; 74.72.Bk; 74.25.Nf.

A.I.M. Rae, E. M. Forgan, and R. A. Doyle, "The Interpretation of Magnetization and Entropy Jumps in the Flux-Line Lattice." Submitted to Nature. School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham B15 2TT, UNITED KINGDOM; telefax +44 121 414-6709 or -4577.

E. Sudhakar Reddy and T. Rajasekharan, "Microstructural Evolution of the nu-Phase in the Cu-Sn System." To be published in J. Mater. Res. Defence Metallurgical Research Laboratory, P.O. Kanchanbagh, Hyderabad 500 058, INDIA; telefax +91 40-239683 or -218439; e-mail vsbsp@uohyd.ernet.in. Key words: melt texturing, Cu-Sn, domains, platelets.

T. M. Rice, Stephan Haas, Manfred Sigrist, and Fu-Chun Zhang, "Lightly Doped t-J Three-Leg Ladders: An Analog for the Underdoped Cuprates." Submitted to Phys. Rev. B. Contact Stephan Haas, Theoretical Physics, ETH-Hoenggerberg, CH-8093, Zurich, SWITZERLAND; telephone +41 1 633 2575; telefax +41 1 633 1115; e-mail haas@itp.ethz.ch. 74.20.Mn; 71.27.+a.

Valery I. Rupasov, "Exactly Solvable Model of Superconducting Magnetic Alloys." Department of Physics, University of Toronto, Ontario, CANADA M5S 1A7 and Landau Institute for Theoretical Physics, Russian Academy of Sciences, Moscow, RUSSIA; e-mail rupasov@physics.utoronto.ca; preprint also available at cond-mat@xxx.lanl.gov (#9706063).

G. J. Schmitz, A. Tigges, and J. C. Schmidt, "Microstructural Aspects of Joining Superconductive Components Using (RE)Ba2Cu3O7-x Solder." To be published in Supercond. Sci. & Technol.: Proc. of Supercond. Mater. Aspects--Res. & Technol. (SMART 97), Liege, Belgium, June 26-29, 1997. Materialforschung, ACCESS e.V., Intzestrasse 5, D-52072 Aachen, GERMANY; telephone +49 241 806721; telefax +49 241 38578; e-mail gjs@gi.rwth- aachen.de.

H. R. Shea and M. Tinkham, "Transition Temperature of Josephson Junction Arrays with Long-Range Interaction." McKay Lab, Harvard University, 9 Oxford Street, Cambridge, MA 02138; telephone (617) 495-3297; telefax (617) 495-9230; e-mail shea@rsj.harvard.edu; preprint also available at cond-mat@xxx.lanl.gov (#9706179). 74.50.+r.

T. Startseva, T. Timusk, A. V. Puchkov, D. N. Basov, H. A. Mook, T. Kimura, and K. Kishio, "Doping Dependence of the Pseudogap State in the ab-Plane IR Response of La2-xSrxCuO4." Submitted to Phys. Rev. B. Department of Physics and Astronomy, McMaster University, Hamilton, Ontario, CANADA L8S 4M1; e-mail startst@mcmail.cis.mcmaster.ca; preprint also available at cond-mat@xxx.lanl.gov (#9706145).

D. E. Steinhauer, C. P. Vlahacos, Sudeep Dutta, F. C. Wellstood, and Steven M. Anlage, "Surface Resistance Imaging with a Scanning Near-Field Microwave Microscope." Submitted to Appl. Phys. Lett. Contact Steven M. Anlage, Department of Physics, Center for Superconductivity Research, University of Maryland, College Park, MD 20742-4111; telephone (301) 405-7321; telefax (301) 405-3779; e-mail anlage@squid.umd.edu; Web site http://www.csr.umd.edu. Key words: microwave microscopy, conductivity mapping, surface-resistance imaging, microwave properties, near-field imaging, coaxial resonator.

S. Stintzing and W. Zwerger, "Ginzburg-Landau Theory of Superconductors with Short Coherence Length." To be published in Phys. Rev. B. Sektion Physik, Ludwig-Maximilians-Universitaet Muenchen, Theresienstrasse 37, D-80333 Muenchen, GERMANY; telephone +49 89 2394 4603; telefax +49 89 2394 4517; e-mail sigmund@stat.physik.uni-muenchen.de; preprint also available at cond-mat@xxx.lanl.gov (#9703129). 74.20.De.

H. Szillat, H. Kuhn, Th. Schuster, P. Majewski, M. Seeger, F. Aldinger, and H. Kronmueller, "Magnetic Phase Transitions and Structural Deficiencies in Superconducting Y-Ni-B-C." To be published in Physica C (in press). Max-Planck-Institut fuer Metallforschung, Institut fuer Werkstoffwissenschaft, Pulvermetallurgisches Laboratorium, Heisenbergstrasse 5, D-70569 Stuttgart, GERMANY; telefax +49 711 686 1131; e-mail szillat@aldix.mpi-stuttgart.mpg.de.

T. Terashima, C. Haworth, H. Takeya, S. Uji, H. Aoki, and K. Kadowaki, "A Small Superconducting Gap on Part of the Fermi Surface of YNi2B2C from de Haas-van Alphen Effect." To be published in Phys. Rev. B. National Research Institute for Metals, Sengen 1-2-1, Tsukuba, Ibaraki 305, JAPAN; telephone +81 298 59 5077; telefax +81 298 59 5010; e-mail tera@nrim.go.jp. 74.60.Ec; 74.72.Ny; 74.25.Jb.

A. N. Terentiev, H. J. Lee, C.-J. Kim, and G. W. Hong, "Identification of Magnet and Superconductor Contributions to the ac Loss in a Magnet- Superconductor Levitation System." Submitted to Physica C. Institute for Chemical Physics, Russian Academy of Sciences, 117977 Moscow, RUSSIA; e-mail terenita@glasnet.ru. Key words: levitation, ac loss, eddy current.

J. R. Thompson, L. Krusin-Elbaum, D. K. Christen, K. J. Song, M. Paranthaman, J. L. Ullmann, J. Z. Wu, Z. F. Ren, J. H. Wang, J. E. Tkaczyk, and J. A. DeLuca, "Current-Density Enhancements of the Highest- Tc Superconductors with GeV Protons." Submitted to Appl. Phys. Lett. Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN 37831-6061; telephone (423) 574-0412; telefax (423) 574-6263; e-mail uzt@ornl.gov. 74.60.Jg; 74.60.Ge; 74.25.Ha.

Th. Wolf, A.-C. Bornarel, H. Kuepfer, R. Meier-Hirmer, and B. Obst, "High Irreversibility Fields and Current Densities in NdBa2Cu3O7-d Single Crystals and Melt Textured Samples." To be published in Phys. Rev. B. Forschungszentrum Karlsruhe, Institut fuer Technische Physik, and Universitaet Karlsruhe, Postfach 3640, D-76021 Karlsruhe, GERMANY; telephone +49 7247 82 4885; telefax +49 7247 82 2849. 74.72.Jt; 74.60.Jg; 74.60.Ge.

Q. Xiong, S. Afonso, K. Y. Chen, G. Salamo, and F. T. Chan, "Tl2Ba2CaCu2Oy Superconducting Thin Films on Polycrystalline Al2O3 Substrates with Textured YSZ Buffer Layers." To be published in Physica C (in press). Department of Physics, High Density Electronics Center, University of Arkansas, Fayetteville, AR 72701; telephone (501) 575- 4313; telefax (501) 575-4580. Key words: Tl2Ba2CaCu2Oy thin film, ion- beam-assisted deposition. 74.76.Bz; 74.72.Fq.

Hisao Yamauchi and Maarit Karppinen, "Net Holes and Superconductivity in the Members with n >= 3 of Homologous Series, Tl- and Hg-m2(n-1)n." To be published in J. Supercond.: Proc. of the Int. Workshop on Tl- and Hg-Based Supercond. Mater., Cambridge, United Kingdom, May 25-28, 1997. Materials and Structures Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226, JAPAN; telephone +81 45-924 5315; telefax +81 45-921 6953 or -924 5360; e-mail yamauchi@materia.titech.ac.jp. Key words: Tl- and Hg-superconductors, homologous series, net holes, unequivalent CuO2 planes.

Kun Yang and S. L. Sondhi, "Response of a d_[x^2-y^2] Superconductor to a Zeeman Magnetic Field." Department of Physics, Princeton University, Princeton, NY 08544; e-mail kunyang@ee.princeton.edu; preprint also available at cond-mat@xxx.lanl.gov (#9706148).

Yutaka Yoshida, Yoshiaki Ito, Hisashi Nagai, Yoshiaki Takai, and Izumi Hirabayashi, "Preparation of a-Axis Oriented YBa2Cu3O7-y Films by Metalorganic Chemical Vapor Deposition Using Liquid Sources." To be published in Jpn. J. Appl. Phys. Superconductivity Research Laboratory, International Superconductivity Technology Center (ISTEC), Nagoya 456, JAPAN. Key words: YBa2Cu3O7-y, thin film, MOCVD, a axis, liquid source, orientation.

Alexandre M. Zagoskin, "Magnetic Interference Pattern in a Clean s-Wave- -Normal Metal--d-Wave Superconductor Junction." Submitted to Phys. Status Solidi. Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, B.C., V6T 1Z1, CANADA; e-mail zagoskin@physics.ubc.ca; Web site http://www.vchgroup.de/akademie-verlag/office/pss/rapid/contents/cont- idx.html.

K. Zhang, Y. L. Yang, D. Ponnusamy, A. J. Jacobson, and K. Salama, "Effect of Microstructure on Oxygen Permeation in SrCo0.8Fe0.2O3-d." Preprint #97:052; submitted to J. Mater. Sci. 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: SrCo0.8Fe0.2O3.d membrane, oxygen permeation flux, grain size.

Anatoley T. Zheleznyak, Victor M. Yakovenko, H. D. Drew, and I. I. Mazin, "Phenomenological Interpretations of the ac Hall Effect in the Normal State of YBa2Cu3O7." Submitted to Phys. Rev. B. Department of Physics and Center for Superconductivity Research, University of Maryland, College Park, MD 20742; Victor M. Yakovenko's e-mail yakovenk@nscpmail.physics.umd.edu; preprint also available at cond- mat@xxx.lanl.gov (#9706029). 74.25.Gz; 74.25.Fy; 74.72.-h.

W. J. Zhu and P. H. Hor, "Crystal Structure of New Layered Oxysulfides: Sr3Cu2Fe2O5S2 and Sr2CuMO3S (M=Cr,Fe,In)." Preprint #97:053; submitted to J. Solid State Chem. 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.

W. J. Zhu and P. H. Hor, "Unusual Layered Transition-Metal Oxysulfides: Sr2Cu2MO2S2 (M=Mn,Zn). Preprint #97:054; to be published in J. Solid State Chem. 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: manganese, zinc, copper, oxysulfides.

Peter Ziswiler, Vadim Geshkenbein, and Gianni Blatter, "Deformations and Dynamics of an Elastic String in a Periodic Potential." Preprint #ETH- TH/97-8; to be published in Phys. Rev. B. Theoretische Physik, ETH- Hoenggerberg, CH-8093 Zurich, SWITZERLAND. 74.60.Ge; 74.80.Dm; 05.60.+w.

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

*Oct. 6 - 10, 1997: The Eighth Workshop on rf Superconductivity, Abano Terme (Padova), Italy. Workshop is planned as a forum for novel ideas and to provide channels of communication between accelerator scientists and industries concerned with advanced technologies. Topics are superconductivity cavities for high energy, heavy-ion accelerators, cyclotrons, FELs; high-intensity proton superconducting machines; the push to high accelerating gradients; cavity fabrication, techniques, and novel ideas; niobium properties, thin films, and innovative materials; surface impedance of superconductors; and HTSC materials from research to rf applications. Will also cover future programs dealing with high- intensity structures that are of emerging interest to the community. Special section of the workshop to be dedicated to non-accelerator applications of rf superconductivity such as novel microwave devices (both low Tc and high Tc). Early registration deadline, July 25, 1997. Proceedings to be published. Invited papers to be published as a special issue of Particle Accelerators. For information, contact A. Lombardi, The Eighth Workshop on rf Superconductivity, INFN LNL Via Romea 4, Legnaro (Padua) ITALY; telephone +39 49-8068 358; telefax +39 49-641925; e-mail alombardi@lnl.infn.it.

Oct. 13 - 25, 1997: Second Training Course in the Physics of Correlated Electron Systems and High-Tc Superconductors Vietri sul Mare, Salerno, Italy. Aimed at postdoc-level researchers, courses intend to promote theoretical research in the field of highly correlated electron systems by putting together senior researchers and young researchers. Topics will include impurity effects in highly correlated electron systems, mesoscopic devices, 1D systems, vortex state in d-wave superconductivity, colossal magnetoresistance, numerical techniques (Monte Carlo and Lanczos methods). The courses will be open to twenty young (aged under 35) European researchers. Application deadline, August 30, 1997. Registration fee: $250. A limited number of grants will be available. Requests for application forms and further information should be sent to F. Mancini, Dipartimento di Scienze Fisiche "E.R. Caianiello", Universita' di Salerno, Via S. Allende, I- 84081 Baronissi (SA), Italy; telephone +39 89-965 322; telefax +39 89- 965 275; e-mail: mancini@vaxsa.csied.unisa.it.

*Dec. 1 - 5, 1997: MRS Fall Meeting: Symposium T -- Stability of High-Temperature Superconductors: Robust Materials for Applications. Goal of this symposium is to engage the research community in an examination of those materials aspects that will impact HTS commercialization. Abstracts are solicited in the following areas: multilayer electronics -- thermal cycling and aging effects; Josephson junctions -- interface stability and electromigration; power dependence in thin-film devices; environmental stability and passivation of HTS thin-film devices; chemical substitutions to enhance stability; phase diagrams -- thermodynamic stability of materials; grain alignment and intergrain connectivity; flux pinning, ac losses, and "trapped field" magnets; alloy, sheath, and substrate materials; and HTS systems -- reliability needs for "real world" applications. A joint session is planned with Symposium II: In-Situ Process Diagnostics and Intelligent Materials Processing. A special session will be devoted to the status of HTS commercialization efforts in the United States, Europe, and Japan. For information about this symposium, contact one of the organizers: Kirsten E. Myers, DuPont Superconductivity, Expt. Station, E304/C110, Wilmington, DE 19880-0304, telephone (302) 695-3357, telefax (302) 695-2721, e-mail myerske@esvax.dnet.dupont.com; or Ronald H. Ono, Division 814.03, NIST, 325 Broadway, Boulder, CO 80303, telephone (303) 497-3762, telefax (303) 497-3042, e-mail ono@boulder.nist.gov.

*March 12 - 13, 1998: JFCC International Workshop in Fine Ceramics '98 -- Ceramics Material Systems with Composite Structure, Nagoya, Japan. Topics include fabrication and processing; microstructure control, characterization, and design interface/interface control, characterization, and design; mechanical and functional characterization; and testing methods and nondestructive evaluation. Papers are solicited. Abstract deadline August 31, 1997. Proceedings to be published in Ceramic Transactions. Official language is English. For information, contact Noriyuki Kosuge, c/o JFCC, 2-4-1 Mutsuno, Atsuta, Nagoya 456, Japan; telephone +81 52 871-3500; telefax +81 52 871-3599.

*Sept. 13 - 18, 1998: 1998 Applied Superconductivity Conference, Marriott's Desert Springs Resort, Palm Desert, CA. Major areas: superconducting materials for a wide range of applications, superconducting electronics, and large-scale applications. For information contact Centennial Conferences, telephone (303) 499-2299, telefax (303) 499-2599, e-mail centennial@orci.com.

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Position Available: A postdoctoral position is available for research on highly correlated electron systems at the Dipartimento Scienze Fisiche "E.R. Caianiello," University of Salerno, Italy. Applicant should have experience in methods of quantum field theory applied to condensed-matter physics, superconductivity, magnetism, and phenomenology of high-Tc cuprates. Programming experience in Fortran is required. Research topics include: (1) analysis of models (2D Hubbard model, t-J model, p-d model, etc.); (2) investigation of paramagnetic and superconducting phases (s- and d-wave); (3) calculation of physical quantities (specific heat, susceptibility, conductivity, etc.); and comparison between numerical (Monte Carlo, Lanczos, diagonalization) and experimental data. Ph.D. in condensed-matter physics required. Duration: 12 months, with further 12-month extension possibility; salary: 22.000.000 to 30.000.000 Italian Lira per annum depending on age and experience. Application deadline, July 31, 1997. Prospective candidates are invited to send their CV, list of publication and letters of recommendation to F. Mancini, telephone +39 89-965322; telefax +39 89-965275; e-mail mancini@vaxsa.csied.unisa.it. A formal application must be sent by registered mail to Presidente INFM, Corso Perrone 24, 16152 Genova, Italy. (The application form is available on request by e-mail from mancini@vaxsa.csied.unisa.it.)

Positions open: The Materials and Low Temperature Laboratory (LMBT) of the Physics Institute at Campinas University (UNICAMP), Brazil, has two position openings -- one for a postdoc and the other for a visiting scientist with three or more years of experience after the Ph.D. In both cases, candidates are expected to have strong background in physics and/or materials science for study of the superconducting properties and their relationship with microstructure in type-II superconductors. Expertise in one or more of the following topics is required: mixed- state properties and vortex phases in high-Tc superconductors; single- crystal growth and characterization; and magnetic (SQUID and ac susceptibility) and transport (resistivity, VxI curves, Hall effect) measurements. Salary will be between $1900--3200/month, depending on candidate level. Positions are for one year with possible extension up to three years. Send curriculum vitae with names of references to Oscar F. de Lima, Instituto de Fisica - UNICAMP, 13083-970 Campinas - SP, Brazil; telefax +55 19 2393137; e-mail: delima@ifi.unicamp.br.

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, #14, July 15, 1997.