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, and other agencies, organizations, and individuals.
The e-mail version of the High-Tc Update is sent to e-mail addresses accessible over INTERNET addresses. You can send e-mail messages to the editor at MITRA@AMESLAB.GOV or MITRA@IASTATE.EDU.
The High-Tc Update web page is located at the URL http://www.iitap.iastate.edu/htcu/htcu.html
PLEASE NOTE: Issues of High-Tc Update 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:
SO(5) Theory
A recent paper by S.-C. Zhang (Stanford) [Science 275, 4126 (1997)] has proposed a theory of high-Tc superconductivity that unifies antiferromagnetism (AF) and d-wave superconductivity (SC) and treats them on an equal footing. The antiferromagnetic phase is described by a three-dimensional order parameter N_alpha (alpha = x, y, z), the staggered magnetization. It has spin 1, charge 0, and total momentum (pi,pi). A spin-singlet d-wave superconducting phase is described by a complex order parameter Delta with two real components. This phase has spin 0, charge +-2, and total momentum 0. The basic idea of Zhang's SO(5) theory is to group these five components together into an object called superspin n_a = (Re-Delta, N_x, N_y, N_z, Im-Delta) (a = 1, 2, 3, 4, 5) and to find well-defined rotation operators that can transform AF into SC and vice versa. These operators must have spin 1, charge +-2, and total momentum (pi,pi) in order to bridge the difference between the AF and SC order parameters.
A new preprint by S.-C. Zhang gives a simple introduction to the SO(5) theory and its experimental consequences, which are currently being worked out. The author notes, for example, that the most direct evidence of the SO(5) symmetry comes from the resonant neutron scattering peaks observed in YBCO superconductors below Tc. These resonances have spin 1, momentum (pi,pi), and sharp peaks at omega_0 = 41 meV, 33 meV, and 25 meV for materials with Tc = 92 K, 67 K, and 52 K, respectively. The author identifies these peaks as transitions between harmonic oscillator states arising from a sharp spin-triplet, two- particle collective mode (triplet pi mode or pi resonance). Although this mode exists in both the superconducting and normal states, it couples to neutron scattering probes only when the SC order parameter has a finite value.
A two-particle tunneling experiment is proposed by Y. Bazaliy et al. (Stanford) to directly probe the pi resonance. The proposed sample consists of a Josephson junction made out of a lower Tc superconductor (layer C), a thin (less than a coherence length) layer of an antiferromagnetic insulator (layer B), and a bulk higher Tc superconductor (layer A). [For example, the superconductors could be a pair of YBCO superconductors, one underdoped (C) and the other optimally doped (A).] The basic idea is that when the temperature T lies between the two superconducting transition temperatures (T_[cC] < T < T_[cA]), the BCS pairing condensate of the bulk superconductor A acts as a classical external field coupling to the two-particle quantum operators in the normal state of layer C. The antiferromagnetic layer is needed to transfer center-of-mass momentum (pi,pi) to the Cooper pair and simultaneously flip its spin, so that it has exactly the same quantum number as the pi resonance on the other side of the junction. The authors predict a sharp pole in the tunneling current when the bias voltage obeys eV_0 = omega_0/2, where omega_0 is the energy of the pi resonance in layer C.
Another possible consequence of the SO(5) theory is that, as shown in a preprint by D. P. Arovas (UCSD-La Jolla) et al., a superconducting vortex in underdoped high-Tc superconductors may have an antiferromagnetic core. This type of vortex configuration arises as a topological solution (called a meron configuration) in the SO(5) theory, which can be expressed in terms of Ginzburg-Landau equations with competing AF and SC order parameters. The SO(5) constraint is that the length of the superspin vector is a constant in five-dimensional space. The direction of the superspin, however, can vary; two of the five axes correspond to superconducting states (the SC plane) and the other three to antiferromagnetic states (the AF sphere). A SC vortex with an AF core corresponds to a solution for which, far from the vortex axis, the superspin lies on the SC plane and the SC phase winds around the origin by 2pi. Near the vortex axis, however, the superspin lifts up from the SC plane into the AF sphere in order to minimize the free energy. The authors suggest that this type of vortex could be detected experimentally by muSR and neutron scattering.
Josephson Arrays
The flux noise S_[ph](omega) and finite-frequency conductivity sigma_1(omega) in two-dimensional unfrustrated Josephson-junction arrays have been obtained numerically by I.-J. Hwang et al. (Ohio State), who solved the equations of the coupled overdamped resistively shunted junction (RSJ) model with Langevin noise. The authors found that S_[ph](omega) proportional to omega^[-3/2] at high frequencies omega and that it flattens at low omega, indicative of vortex diffusion; sigma_1(omega) proportional to omega^[-2] at high frequencies. Both quantities show evidence of critical slowing down and possibly scaling behavior near the Kosterlitz-Thouless-Berezinskii (KTB) transition.
A preprint by M. Barahona (MIT) et al. reports simulations of the dynamics of fully frustrated, underdamped Josephson arrays. Experiments have revealed similarities among the dc current-voltage characteristics of several kinds of square and triangular arrays, where two resonant voltages are observed. The simulations reveal that a dynamical checkerboard solution underlies these similarities.
Quantum phase transitions in two-dimensional superconducting arrays with general capacitance matrices and discrete charge states have been investigated by B. J. Kim et al. (Seoul National). The authors used perturbation theory and simulated annealing to obtain zero-temperature phase diagrams, which display various lobe-like structures of insulating solid phases.
More Theory
As shown by I. F. Herbut (UBC), the continuum version of the dual theory for a system of two-dimensional quantum disordered bosons with statistical particle-hole symmetry admits a disordered critical point within a renormalization group calculation at fixed dimension. The author obtains the following universal conductivity and critical exponents at the superfluid-Bose glass transition (superconductor- insulator transition in two dimensions): sigma_c = 0.25(2e)^2/h, nu = 1.38, and z = 1.93.
Slave-boson calculations have been carried out by R. S. Markiewicz (Northeastern) in the three-band t-J model for the high-Tc cuprates. Phonon-induced Van Hove nesting leads to a phase separation between a hole-doped domain and a (magnetic) domain near half filling, with long- range Coulomb forces limiting the separation to a nanoscopic scale. The author finds that the doping dependence provides an excellent description of photoemission and thermodynamic experiments on pseudogap formation in underdoped cuprates.
Using an unconventional Fermi-liquid model, G. Kastrinakis (Illinois- Urbana) has obtained a linear-in-T resistivity and a linear-in-1/epsilon optical conductivity, provided the interacting Fermi liquid has strong peaks in its density of states (Van Hove singularities in two dimensions) near the chemical potential. By introducing an Ansatz for the fermionic susceptibility of the carriers, the author obtains a d_[x^2-y^2] superconducting gap with Tc > 120 K for a nearest-neighbor hopping t = 250 meV.
A preprint by D. Coffey (SUNY-Buffalo) shows that interactions among quasiparticles in low-dimensional superconductors are much stronger than in conventional 3D superconductors because of long-range correlations from the Coulomb interaction.
An analysis of resonant tunneling transport along the c axis in high-Tc cuprates has been performed by A. A. Abrikosov (Argonne) for the case that the concentration of localized resonant centers is low and the tunneling via different centers is incoherent. The author finds that the supercurrent along the c axis vanishes when the order parameter has d-wave symmetry and the tunneling is incoherent.
Vortices
Monte Carlo simulations in conjunction with finite-size scaling analysis have been used by A. K. Nguyen and A. Sudbo (Trondheim) to investigate the (B,T) phase diagram in uniaxial anisotropic high-Tc superconductors in zero magnetic field (B = 0) and in intermediate magnetic fields (0 < B << B_[c2]) for various mass anisotropies. In zero magnetic field, the authors find (for all anisotropies considered) a single second-order phase transition mediated by an Onsager vortex-loop unbinding transition (blowout). This is the superconductor-normal metal transition. In the intermediate magnetic field regime, the authors find two anomalies in the specific heat: The first (at temperature T_m) is associated with the melting transition of the vortex lattice, and the Lindemann ratio at melting is found to be c_L ~~ 0.24. The second (temperature T_Z) is where phase coherence in the BCS order parameter across the sample along the field direction is destroyed. The authors use a finite-size scaling analysis to argue that T_m = T_Z in the thermodynamic limit. The authors also find that the entropy jump at the vortex-lattice melting transition increases rapidly with mass anisotropy.
Using an analytic theory of a first-order supersoftening transition in which the shear modulus jumps discontinuously, H. M. Carruzzo and C. C. Yu (UC-Irvine) suggest that the vortex transition observed with increasing temperature or magnetic field may not be a solid-liquid transition but rather a first-order transition from an ordinary vortex lattice to a soft vortex solid containing vacancies and interstitial vortex lines. The authors find that the first-order line ends at a critical point.
An enhancement of the nuclear quadrupole resonance (NQR) signal in the presence of a dc magnetic field H in YBa2Cu3O7 is reported by H. Shaked (Ben Gurion) et al. The enhancement occurs only at T < Tc, and its variation with H and the rf field amplitude indicates that it stems from the rf response of vortices in the superconductor. The authors suggest that this effect will be useful as a probe of vortex dynamics in high-Tc superconductors.
The scaling behavior of the dc conductivity sigma_[xx] with current perpendicular to the magnetic field near a vortex-glass (VG) transition has been addressed by R. Ikeda (Kyoto) using a Ginzburg-Landau model, the Kubo formula, and an assumed universal scaling behavior of the VG correlation function. The author discusses reasons why the universal scaling of sigma_[xx] can be apparently nonuniversal even deep in the VG critical region.
A preprint by T. Blum (Manchester and Virginia) and M. A. Moore (Manchester) reports calculations of the Aslamazov-Larkin term in the ab-plane conductivity of a vortex liquid in a magnetic field along the c axis. The authors use two time-dependent Ginzburg-Landau approaches, one explicitly applying a uniform electric field and the other using the Kubo formula to extract the linear response. The authors consider questions of nonlocality, length scales, and the effects of weak disorder.
The topological term in the effective action for the electrically neutral BCS system is discussed in a preprint by G. E. Volovik (Helsinki University of Technology and Landau Institute). The author calculates the transverse force acting on the vortex in the limit of a smooth vortex core and vanishing interlevel distance in the vortex core.
According to N. B. Kopnin (Landau Institute and Orsay) and G. E. Volovik (Landau Institute and Helsinki University of Technology), superclean d- wave superconductors with Delta_[infinite]^2tau/E_F >> 1 display a novel kind of vortex dynamics: At low temperatures, both the dissipative and transverse components of the flux-flow conductivity approach universal values independent of relaxation. The authors explain the finite dissipation in the superclean limit in terms of Landau damping via zero- frequency vortex modes that appear because of minigap nodes in the bound-state spectrum in the vortex core.
The Hall angle alpha has been measured by J. Z. Wu (Kansas) et al. in epitaxial HgBa2CaCu2O6+d (Hg-1212) films in which flux pinning has been tuned using irradiation-induced columnar defects. The authors found that the mixed state can be divided into a pinning-independent (PI) region and a pinning-effective (PE) region, the Hall angle behaving differently in the two regions. The authors found that pinning is not the mechanism for the Hall-angle sign reversal, since the reversal is clearly seen in the PI region, but that pinning can reduce the value of alpha in the PE region.
Using a generalized London model with nonlocal electrodynamics derived from a simple microscopic model, M. Franz (Johns Hopkins) et al. have investigated equilibrium vortex lattice structures in superconductors with unconventional order parameters. The authors find a rich phase diagram containing triangular, centered rectangular, and square lattices with various orientations relative to the crystal lattice, depending upon magnetic field and temperature.
A preprint by T. Pe et al. (Ames Lab-Iowa State) reports calculations of the current-voltage characteristics of moving two-dimensional pancake vortex lattices in finite stacks of Josephson-decoupled superconducting multilayers carrying transport current only in the top layer. The authors also calculate the critical decoupling current, at which the pancake lattice in the top layer first shears away from the pancake lattices in the other layers.
RBa2Cu3O7-d
A preprint by B. Keimer (Princeton) et al. reports on inelastic neutron scattering experiments concerning the doping dependence of the energy and spectral weight of the sharp magnetic resonance peak in YBa2Cu3O7-d. As doping and Tc increase, the authors find that the energy E_[res] of the peak increases, while the integrated spectral weight of the enhanced part of the susceptibility Integral[domega-chi_+"(q,omega)] decreases.
Inelastic neutron scattering also has been used by P. Bourges (CEA-CNRS, Saclay) et al. to determine the dynamic spin fluctuations in an underdoped high-temperature superconductor YBa2Cu3O6.8. The magnetic resonance that occurs around 40 meV in overdoped samples is shifted to a lower energy, 34 meV, in this sample. A constant ratio, E_[res]/k_BTc = 4.9+-0.2, almost independent of the doping level, is found, supporting the idea that the resonance energy is proportional to the superconducting energy gap.
Another preprint by P. Bourges (CEA-CNRS, Saclay) et al. reports a detailed inelastic neutron scattering study of the absolute dynamical spin susceptibility chi(q,omega) in the underdoped cuprate YBa2Cu3O6.5 (Tc = 52 K) over a wide range of energies (2-200 meV) and temperatures (5-200 K). The authors observed spin excitations of two different symmetries (even and odd under exchange of two adjacent CuO2 layers), which have different temperature dependencies. The excitations show dispersive behavior at high energies.
The critical current density of R-123 composites, where R represents mixtures of equal amounts of three rare earths selected from Nd, Sm, Eu, and Gd, has been found by M. Muralidhar (SRL-ISTEC) et al. to be superior to that of YBa2Cu3O7-d and NdBa2Cu3O7-d bulk superconductors. For (Nd0.33Eu0.33Gd0.33)Ba2Cu3O7-d [(Nd-Eu-Gd)-123], the Jc was found to be 5 x 10^4 A/cm^2 at 77 K and 2 T.
A study of the distribution of Y2BaCuO5 (211) particles left after melt texturing of YBa2Cu3O7-d (123) has been carried out by C.-J. Kim et al. (KAERI). The tracks of 211 particles reveal details of the anisotropic growth behavior and the shape of the growing 123 domain.
Large increases of Jc have been found by R. Weinstein et al. (TCSUH) in melt-textured YBa2Cu3O7-d containing U^[235] and U^[238] after thermal- neutron irradiation. The authors note that this process appears to produce the highest Jc at low cost and low radioactivity.
Bi Cuprates
A preprint by F. Hamed et al. (Simon Fraser) reports c-axis current- voltage curves of nominal Bi2Sr2CaCu2O8+d (Bi-2212) whiskers in a magnetic field applied along the a direction. In zero applied field, the authors observed branches characteristic of series-connected intrinsic Josephson junctions, and these branches were retained in low fields. At high currents, all the branches merged into a linear I-V dependence, extrapolating to the origin.
The question of how to magnetically determine the true or potential transport critical current density of multifilamentary HTS/Ag strands in the presence of bridging and generalized sausaging has been addressed by M. D. Sumption (Ohio State) et al. The authors apply their analysis to the bridged magnetizations of round multifilamentary Bi-2212/Ag strands.
The self-field ac losses of mono- and multifilamentary (Bi,Pb)-2223 silver-sheathed tapes carrying an ac current have been measured by C. M. Friend (BICC Cables) et al. The authors find that the losses depend on the details of how the ribbon-like filaments are distributed within the tape. The authors present evidence that tapes in which the filaments are arranged in columns have lower losses than those in which the filaments are interdigitated.
A preprint by M Kiuchi (Kyushu Institute of Technology) et al. reports on the scaling of current-voltage curves and critical pinning-force density in superconducting Bi-2223 silver-sheathed tapes. The authors found that the dynamic and static vortex-glass critical exponents obtained from the analysis changed appreciably as a function of the applied magnetic field.
Other Cuprates
The atomic arrangement about the Sr atoms in La2-xSrxCuO4 has been investigated by D. Haskel (Washington) et al. using Sr K-edge polarized x-ray absorption fine structure (EXAFS). The authors find that when Sr resides at a La lattice site, it considerably distorts the local atomic environment and leads to a splitting of the apical oxygen site, indicating that Sr not only donates a hole but also induces a polaron.
As reported by P. Yang and C. M. Lieber (Harvard), nanorod/superconductor composites have been formed by depositing Tl2Ba2Ca2Cu3O10 (Tl-2223) thick films on high-density nanorod MgO arrays grown on MgO single-crystal substrates. Electron microscopy studies show that this approach produces a high density of columnar defects normal to the CuO2 planes within crystal grains of the composites. The nanorod/superconductor composites exhibited enhanced critical current densities and an upward shift in the irreversibility line compared with reference samples.
Mossbauer studies of YBa2Cu3O7-d and Nd2-xCexCuO4 in which Cu atoms are replaced by [57]^Co atoms are reported by A. Nath (Drexel) et al. The experiments confirm that Nd2-xCexCuO4 is truly an electron-doped superconductor.
Films
A method of forming in-plane-aligned YSZ (1-2 micrometers) and YBCO thin-film tapes on flexible Ni-based alloy substrates (Hastelloy) with high deposition rates of 0.5 micrometer/min using continuous pulsed laser deposition (PLD) is reported by K. Hasegawa (Sumitomo) et al. Using the technique of inclined-substrate deposition (ISD), the authors found that it is possible to achieve in-plane alignment without using ion-beam-assisted deposition (IBAD). The authors report that a hundred YBCO tapes of length 1 m were fabricated with 77 K self-field Jc values more than 10^4 A/cm^2. The authors have obtained a Jc(77 K, 0 T) = 1.5 x 10^5 A/cm^2 over a 1 m length with in-plane-aligned YBCO, and they were able to achieve an overall (engineering) critical current density (including substrate) of 4 x 10^3 A/cm^2 for a sample of length 10 cm.
Thick (300-400 micrometers) films of Tl-based cuprates have been grown by S. H. Yoo (Kansas) et al. using a sol-gel technique with two steps: the deposition of a Tl-free precursor film followed by Tl-vapor annealing. The authors obtained zero-resistance superconducting transition temperatures of 120 K on polycrystalline MgO substrates for Tl-1223 (TlBa2Ca2Cu3O9) films and 124 K on (100) LaAlO3 and polycrystalline MgO for Tl-2223 (Tl2Ba2Ca2Cu3O10) films.
A method to produce thick (10-60 micrometers) layers of YBa2Cu3O7-d using a plasma spray technique (PST) is described in a preprint by A. G. Cunha (Urca and Vitoria) et al.
The metastable states induced by photoexcitation, oxygen disorder, and both effects combined have been studied by J. Guimpel et al. (Bariloche) in GdBa2Cu3O7-d thin films. In studying the relaxation dynamics, the authors find that the persistent photoconductivity and oxygen-disordered states relax independently with different time scales, but both involve oxygen movement.
An unusual crystal structure of nonsuperconducting YBa2Cu3O7-d films grown at reduced substrate temperatures by laser ablation on CeO2/YSZ buffered Si substrates is reported by S. Linzen (Jena) et al. The model of a simple cubic YBCO perovskite unit cell describes some but not all of the experimental results.
A new annealing procedure to achieve well-defined surfaces of SrTiO3 single-crystal and bicrystal substrates is described by Q. D. Jiang and J. Zegenhagen (TCSUH). Annealing SrTiO3 (001) substrates in oxygen and then in ultrahigh vacuum produces uniformly TiO2-terminated, atomically flat and ordered (001) surfaces.
The current-phase relation of high-Tc YBa2Cu3O7-d bicrystal and step- edge junctions has been measured by V. Zakosarenko et al. (Jena). The current-phase relation for the bicrystal junction is nearly sinusoidal, but that for the step-edge junction is strongly nonsinusoidal.
Applications
Measurements of the ac losses and current distributions of Bi-2223 three-strand parallel conductors are reported by M. Iwakuma (Kyushu) et al. The authors report that the ac losses and transport currents are distributed equally among the strands when the three strands are evenly transposed during the winding process.
The design and fabrication of a 500 kVA-class superconducting power transformer operated in sub-cooled liquid nitrogen is reported by K. Funaki (Kyushu) et al. The primary and secondary windings were three- and six-strand parallel conductors of Bi-2223 Ag-sheathed multifilamentary tapes, respectively. The strands of the parallel conductors were transposed several times to achieve a uniform current distribution among them.
The performance of a prototype fault-current limiter fabricated from YBCO tapes is reported by K. Hasegawa (Sumitomo) et al. The authors used a stack of ten YBCO one-turn coils, each constructed of YBCO ISD tape of length 15 cm. The I_c values of the ten coils ranged from 16.9 A to 24.0 A with average value of 19.3 A, and the average Jc value was 1.7 x 10^5 A/cm^2.
Other Activities
The magnetic-field-induced breakdown of superconductivity in nm-scale metal grains having a mean electron-level spacing of the order of the bulk gap has been investigated theoretically by F. Braun (Karlsruhe) et al. The authors find that the dominant mechanism for destroying pairing correlations in ultrasmall grains is Pauli paramagnetism.
Models describing the complicated shapes of the highly branched and fingered macroscopic magnetic-flux-containing normal domains in the intermediate state of type-I superconductors are analyzed in a paper by A. T. Dorsey (Florida) and R. E. Goldstein (Arizona).
Overviews
Basic concepts of the classical mechanical deformation theory are reviewed by Z. Han et al. (NKT) and applied to the processing of Bi-Sr- Ca-Cu-O/Ag composites made by the powder-in-tube method. The authors present descriptions of various deformation processes including pressing, rolling, drawing, and extrusion (53 refs.).
The evidence for two distinct kinds of carriers in the cuprate superconductors is presented in an overview by D. Mihailovic (Ljubljana) and K. A. Mueller (Zurich). The authors summarize results from x-ray absorption fine-structure spectroscopy (EXAFS), neutron pair distribution function (PDF), NMR, NQR, EPR, Mossbauer, optical conductivity, time-resolved response, and high-frequency electrodynamics experiments (45 refs.).
An overview by D. Mihailovic (Ljubljana) discusses the evidence for the existence of two electronic subsystems in the normal state of the high- temperature superconductors, one with band-like properties and the other with localized (polaronic) states (31 refs.).
The temperature dependence of the anisotropic magnetoresistance in the high-temperature superconductors YBa2Cu3O7-d and Bi2Sr2CaCu2O8+d is discussed by W. Lang (Wien) et al. with a focus on the behavior at temperatures significantly above Tc. The authors find that the effects of superconducting fluctuations are evident up to at least 2Tc (29 refs.).
Ph.D. Thesis
The Ph.D. thesis of N. Dieckmann (Hamburg) discusses the use of scanning micro- and macro-Raman spectroscopy (SMRS) to characterize thin films and patterned devices made of YBa2Cu3O7. The author also describes studies of magnetic excitations in YxPr1-xBa2Cu3O7 using resonant and temperature-dependent Raman spectroscopy. Antiferromagnetic fluctuations were found in the superconducting regime in YxPr1-xBa2Cu3O7 films (224 refs.). Raman spectra showing high-energy antiferromagnetic spin excitations in a Y0.8Pr0.2Ba2Cu3O7 film also are presented in the closely related preprint by M. Ruebhausen et al. (Hamburg).
Contributed by John R. Clem
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. A. Abrikosov, "Coherent Versus Incoherent Resonant Tunneling in High- Tc Cuprates." Contact Janice Coble, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439; telefax (708) 252-9595; e-mail janice_coble@qmgate.anl.gov. 74.20.Mn; 74.25.Dw; 74.25.Fy.
G. Aldica, P. Badica, S. Mandache, and S. Popa, "The Influence of Synthesis Environment on Magnetic Properties and Phase Content in BSCCO Superconducting Ceramic Obtained by Spray-Frozen, Freeze Drying Technique." Submitted to ECERS '97, Versailles-Paris, France, June 22- 26, 1997. Institute of Physics and Technology of Materials, PO Box MG- 7, Bucharest-Magurele, ROMANIA; telefax +40 1 420 3700; e-mail aldica@roifa.ifa.ro. Key words: BSCCO superconducting ceramic, volumetric characteristics, x-ray diffraction, ac susceptibility, dc magnetization, spray-frozen freeze-drying technique.
Daniel P. Arovas, A. J. Berlinsky, C. Kallin, and Shou-Cheng Zhang, "Superconducting Vortex with Antiferromagnetic Core." Submitted to Phys. Rev. Lett. Department of Physics, University of California at San Diego, La Jolla, CA 92093; e-mail dpa@borges.ucsd.edu; preprint also available at cond-mat@xxx.lanl.gov (#9704048). 74.20.De; 74.25.Dw; 74.25.Ha.
Pavel V. Avramov, Sergei G. Ovchinnikov, Vladimir A. Gavrichkov, and Sergei Ph. Ruzankin, "Theory of X-ray Absorption Spectra of Strongly Correlated Copper Oxides." To be published in Physica C (in press). L. V. Kirenskii Institute of Physics, Siberian Branch of Russian Academy of Sciences, Krasnoyarsk 660036, RUSSIA. Key words: electron correlations, p-d model, x-ray absorption spectra.
P. Badica, G. Aldica, V. V. Morozov, A. F. Alexeev, and T. Y. Gridasova, "The Influence of Synthesis Environment and Time on Volumetric Characteristics of BSCCO Superconducting Ceramic Obtained by Spray- Frozen, Freeze Drying Technique." Submitted to ECERS '97, Versailles- Paris, France, June 22-26, 1997. Institute of Physics and Technology of Materials, PO Box MG-7, Bucharest-Magurele, ROMANIA; telefax +40 1 420 3700; e-mail badica@roifa.ifa.ro. Key words: BSCCO, superconducting ceramic, synthesis environment, spray-frozen freeze-drying technique, volumetric characteristics.
P. Badica, G. Aldica, V. V. Morozov, S. Popa, and S. Mandache, "The Influence of Sintering Environment and Intermediate Grounding on the Scattering of the Superconducting Characteristics in BSCCO Ceramic Produced by Spray-Frozen, Freeze Drying Method." Submitted to Appl. Supercond. Institute of Physics and Technology of Materials, PO Box MG- 7, Bucharest-Magurele, ROMANIA; telefax +40 1 420 3700; e-mail badica@roifa.ifa.ro. Key words: superconductor, Bi(Pb)-Sr-Ca-Cu-O, x- ray diffraction, electric resistivity, dc magnetization, ac susceptivity, spray-frozen freeze-drying technique.
M. Barahona, E. Trias, T. P. Orlando, A. E. Duwel, H.S.J. van der Zant, S. Watanabe, and S. H. Strogatz, "Resonances of Dynamical Checkerboard States in Josephson Arrays with Self-Inductance." Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA 02139; e-mail mauricio@loki.stanford.edu; preprint also available at patt-sol@xxx.lanl.gov (#9703008). 74.50.+r; 05.45.+b; 74.40.+k.
Y. Bazaliy, E. Demler, and S. C. Zhang, "Search for the pi Resonance in Two Particle Tunneling Experiments of YBCO Superconductors." Department of Physics, Stanford University, Stanford, CA 94305; E. Demler's e-mail eugene@quantum.stanford.edu; preprint also available at cond- mat@xxx.lanl.gov (#9704022). 74.72.Bk; 74.72.-h; 74.20.-z; 74.50.+r.
T. Blum and M. A. Moore, "Perturbative Studies of the Conductivity in the Vortex-Liquid Regime." To be published in Phys. Rev. B. Department of Physics, Jesse W. Beams Laboratory, McCormick Rd., University of Virginia, Charlottesville, VA 22901; e-mail teb2n@virginia.edu; preprint also available at cond-mat@xxx.lanl.gov (#9704132).
P. Bourges, H. F. Fong, L. P. Regnault, J. Bossy, C. Vettier, D. L. Milius, I. A. Aksay, and B. Keimer, "High Energy Spin Excitations in YBa2Cu3O6.5." Submitted to Phys. Rev. Lett. Laboratoire Leon Brillouin, CEA-CNRS, CE Saclay, F-91191 Gif sur Yvette, FRANCE; e-mail bourges@bali.saclay.cea.fr; preprint also available at cond- mat@xxx.lanl.gov (#9704073). 74.20.Mn; 25.40.Fq; 74.72.Bk.
P. Bourges, L. P. Regnault, Y. Sidis, J. Bossy, P. Burlet, C. Vettier, J. Y. Henry, and M. Couach, "Shifting of the Magnetic Resonance Peak to Lower Energy in the Superconducting State of Underdoped YBa2Cu3O6.8." To be published in Europhys. Lett. Laboratoire Leon Brillouin, CEA- CNRS, CE Saclay, F-91191 Gif sur Yvette, FRANCE; e-mail bourges@bali.saclay.cea.fr; preprint also available at cond- mat@xxx.lanl.gov (#9704101). 74.20.Mn; 25.40.Fq; 74.72.Bk.
Fabian Braun, Jan von Delft, D. C. Ralph, and M. Tinkham, "Paramagnetic Breakdown of Superconductivity in Ultrasmall Metallic Grains." Institute fuer Theoretische Festkoerperphysik, Universitaet Karlsruhe, D-76128 Karlsruhe, GERMANY; e-mail fbraun@tfp.physik.uni-karlsruhe.de; preprint also available at cond-mat@xxx.lanl.gov (#9704181). 74.20.Fg; 74.25.Ha; 74.80.Fp.
Herve M. Carruzzo and Clare C. Yu, "First Order Supersoftening Transition of Vortex Lattices." Department of Physics and Astronomy, University of California at Irvine, Irvine, CA 92697.
H. L. Chiueh and D. S. Chuu, "Cooperative Behavior of RVB, Flux Phase, and Antiferromagnetic States." To be published in Physica C (in press). Contact D. S. Chuu, Department of Electrophysics, National Chiao Tung University, Hsinchu, Taiwan, REPUBLIC OF CHINA. Key words: antiferromagnetic order, holons, phase diagram, RVB model, spinons.
D. Coffey, "Quasiparticle Interactions in Two and Three Dimensional Superconductors." Department of Physics, State University of New York, Buffalo, NY 14260.
A. G. Cunha, M.T.D. Orlando, F. G. Emmerich, C. Larica, and E. M. Baggio-Saitovitch, "Optimization of YBa2Cu3O7 Superconducting Thick Layers Produced by Plasma Spray Technique." 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. Universidade Federal do Espito Santo, Centro de Ciencias Exatas, Departamento de Fisica, Av. Fernandoi Ferrari, s/n, Bairro de Goiabeiras, Cidade de Vitoria, CEP 29060-900 Espirito Santo, BRAZIL.
T. A. Deis, N. G. Eror, P. Krishnaraj, M. Lelovic, and U. Balachandran, "Effects of Stoichiometry and Ag Doping on the Structure and Critical Temperature of Bi2Sr2CaCu2O8+d Superconductors." Submitted to Physica C. Department of Materials Science and Engineering, University of Pittsburgh, Pittsburgh, PA 15261; preprint also available from Janice Coble, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439; telefax (708) 252-9595; e-mail janice_coble@qmgate.anl.gov. Key words: Ag, Bi2Sr2CaCu2O8+d, doping, stiochiometry.
O. F. de Lima, M. A. Avila, and C. A. Cardoso, "Study of Paramagnetic Frozen States in Superconducting Nb and Ta Samples." 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. Instituto de Fisica, Universidade Estadual de Campinas, Unicamp, 13083-970 Campinas, SP, BRAZIL; telephone +55 192 39 7766; e-mail delima@ifi.unicamp.br.
O. F. de Lima and R. A. Ribeiro, "Diamagnetic Peaks in Magnetization Versus Temperature Curves Caused by Flux Trapped Relaxation Observed in YBa2Cu3O7-d Samples." 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. Instituto de Fisica, Universidade Estadual de Campinas, Unicamp, 13083-970 Campinas, SP, BRAZIL; telephone +55 192 39 7766; e-mail delima@ifi.unicamp.br.
Nils Dieckmann, "Raman and Micro-Raman Analysis of YxPr1-xBa2Cu3O7 Single Crystals, Films, and Devices." Submitted as a Ph.D. thesis (Universitaet Hamburg). Institut fuer Angewandte Physik, Universitaet Hamburg, Jungiusstrasse 11, D-20355 Hamburg, GERMANY; telephone +49 40 4123 4202; telefax +49 40 4123 4368; e-mail dieckmann@physnet.uni- hamburg.de.
Alan T. Dorsey and Raymond E. Goldstein, "The Shapes of Flux Domains in the Intermediate State of Type-I Superconductors." Submitted to Phys. Rev. B. Department of Physics, University of Florida, Gainesville, FL 32611; e-mail dorsey@phys.ufl.edu; preprint also available at cond- mat@xxx.lanl.gov (#9704161).
Herman J. Fink, "Supercurrents Through SNS Proximity Induced Junctions." Submitted to Phys. Rev. B. Department of Electrical and Computer Engineering, University of California, Davis, CA 95616.
M. Franz, Ian Affleck, and M.H.S. Amin, "Theory of Equilibrium Flux Lattices in Unconventional Superconductors." Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218; e-mail franz@pha.jhu.edu; preprint also available at cond-mat@xxx.lanl.gov (#9704165).
C. M. Friend, S. A. Awan, L. Le Lay, S. Sali, and T. P. Beales, "Explaining the Self-Field ac Loss Behavior of Silver-Clad (Bi,Pb)-2223 Tapes for Power Engineering Applications." To be published in Physica C. BICC Cables Limited, Wrexham Technology Centre, Wrexham, Wales LL13 9XP, UNITED KINGDOM; telephone +44 1978 662-612 or -345; telefax +44 1978 662-464. Key words: applications of high-Tc superconductors, ac loss.
K. Funaki, M. Iwakuma, M. Takeo, K. Yamafuji, J. Suehiro, M. Hara, M. Konno, Y. Kasagawa, I. Itoh, S. Nose, M. Ueyama, K. Hayashi, and K. Sato, "Preliminary Tests of a 500 kVA-Class Oxide Superconducting Transformer Cooled by Subcooled Nitrogen." Presented at the Appl. Supercond. Conf. (ASC'96), Pittsburgh, PA, Aug. 25-30, 1996. Kyushu University 36, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-81, JAPAN.
U. Gasser, P. Allenspach, J. Mesot, and A. Furrer, "Crystal Electric Field Splitting of R^[3+]-Ions in RNi2B2C (R = rare earth)." 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. Laboratory for Neutron Scattering, Eidgenoessische Technische Hochschule Zurich and PSI, Paul Scherrer Institut, CH-5232 Villigen PSI, SWITZERLAND; e-mail urs.gasser@psi.ch.
J. Guimpel, B. Maiorov, E. Osquiguil, G. Nieva, and F. Pardo, "Interrelation Between Persistent Photoconductivity and Oxygen Order in GdBa2Cu3Ox Thin Films." Submitted to Phys. Rev. B. Low Temperature Laboratory, Centro Atomico Bariloche and Instituto Balseiro, Comision Nacional de Energia Atomica, Avda. Bustillo 9500, 8400 S. C. de Bariloche, R. N., ARGENTINA; telephone+54 944 45 171; telefax +54 944 45 299; e-mail jguimpel@cab.cnea.edu.ar.
F. Hamed, S. Gygax, and A. E. Curzon, "c-Axis IV Curves in Bi2212 Whiskers with Applied Magnetic Fields Parallel to the a-Axis." To be published in Physica C. Department of Physics, Simon Fraser University, Burnaby, British Columbia, CANADA V5A 1S6; S. Gygax's telephone (604) 291-4465; telefax (604) 291-3592; e-mail gygax@sfu.ca.
F. Hamed, S. Gygax, and A. E. Curzon, "Unusual Resistive Transitions in Two-Phase Superconducting Single Crystals: BiSrCaCuO Whiskers." To be published in Physica C. Department of Physics, Simon Fraser University, Burnaby, British Columbia, CANADA V5A 1S6; S. Gygax's telephone (604) 291-4465; telefax (604) 291-3592; e-mail gygax@sfu.ca.
Z. Han, P. Skov-Hansen, and T. Freltoft, "The Mechanical Deformation Process of Superconducting BiSrCaCuO/Ag Composites." Submitted to Supercond. Sci. Tech. NKT Research Center, Sognevej 11, DK-2605 Brondby, DENMARK; telephone +45 4348-3529 or -3500; telefax +45 4363- 0099; e-mail z.han@nkt-rc.dk.
K. Hasegawa, N. Yoshida, K. Fujino, H. Mukai, K. Hayashi, K. Sato, S. Honjo, Y. Sato, T. Ohkuma, H. Ishii, Y. Iwata, and T. Hara, "In-Plane Aligned YBCO Thin Film Tape Fabricated by Pulsed Laser Deposition." To be published in the Proc. of the 9th Int. Symp. on Supercond. (ISS'96), Sapporo, Hokkaido, Japan, Oct. 21-24, 1996. Osaka Research Laboratories, Sumitomo Electric Industries, Ltd., 1-1-3 Shimaya, Konohana-ku, Osaka 554, JAPAN; telefax +81 6 466 5704; e-mail khasegawa@okk.sei.co.jp. Key words: YBCO thin film, in-plane alignment, pulsed-laser deposition, high Jc, fault current limiter.
D. Haskel, E. A. Stern, D. G. Hinks, A. W. Mitchell, and J. D. Jorgensen, "Altered Sr Environment in La2-xSrxCuO4." To be published in Phys. Rev. B. Department of Physics, Box 351560, University of Washington, Seattle, WA 98195; telephone (206) 543-0435; telefax (206) 685-0635; e-mail haskel@dirac.phys.washington.edu. 61.10.Lx; 64.60.-i; 74.72.-h.
Igor F. Herbut, "Dual Superfluid-Bose Glass Critical Point in Two Dimensions and the Universal Conductivity." Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, British Columbia, CANADA V6T 1Z1; e-mail herbut@theory.physics.ubc.ca; preprint also available at cond- mat@xxx.lanl.gov (#9704134).
Sun-Li Huang, D. Dew-Hughes, and K. Fossheim, "Comparison of Fully- Reacted and Partly-Reacted Bi2Sr2CaCu2Oy Precursor Powders." 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 Physics, Norwegian University of Science and Technology, Sem Saelandsv. 9, N-7034 Trondheim, NORWAY; telephone +47 7359 3640; telefax +47 7359 3695; e- mail sunlih@phys.unit.no.
M. Huecker, J. Pommer, B. Buechner, V. Kataev, and B. Rameev, "Magnetism of the LTT Phase of Eu Doped La2-xSrxCuO4." Submitted to J. Supercond. II. Physikalisches Institut, Universitaet zu Koeln, D-50937 Koeln, GERMANY.
Ing-Jye Hwang, Seungoh Ryu, and D. Stroud, "Flux Noise and Fluctuation Conductivity in Unfrustrated Josephson Junction Arrays." Department of Physics, Ohio State University, 174 West 18th Avenue, Columbus, OH 43210-1106; telephone (614) 292-5713; telefax (614) 292-5775; e-mail hwang@pacific.mps.ohio-state.edu. 74.50.+r; 74.40.+k; 64.60.Fr.
Ryusuke Ikeda, "Vortex Glass Scaling of Conductivity." Submitted to J. Phys. Soc. Jpn. Department of Physics, Kyoto University, Kyoto 606-01, JAPAN; e-mail ikeda@ton.scphys.kyoto-u.ac.jp. Key words: type-II superconductor, vortex-glass transition.
Masataka Iwakuma, Kazuo Funaki, Kenshi Kanegae, Hironobu Shinohara, Tsuyoshi Wakuda, Masakatsu Takeo, Kaoru Yamafuji, Masayuki Konno, Yusuke Kasagawa, Kenji Okubo, Ikuo Itoh, Shinichi Nose, Munetsugu Ueyama, Kazuhiko Hayashi, and Kenichi Sato, "ac Loss and Current Distribution in Parallel Conductors for Bi2223 HTS Transformer Windings." Presented at the 16th Int. Cryogenic Engineering Conf. and the Int. Cryogenic Materials Conf. (ICEC16/ICMC), Kitakyushu, Japan, May 20-24, 1996. Faculty of Engineering, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812, JAPAN.
Q. D. Jiang and J. Zegenhagen, "Atomic Scale Engineering of SrTiO3 Single Crystal Surfaces and Bicrystal Boundaries for Epitaxial Growth of Oxide Thin Films." Preprint #97:038; to be published in the Proc. of the 1997 MRS Spring Mtg., San Francisco, Calif., Mar. 31 - Apr. 3, 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.
K. Kajantie, M. Karjalainen, M. Laine, and J. Peisa, "Masses and Phase Structure in the Ginzburg-Landau Model." Preprint #CERN-TH/97-62 or HD- THEP-97-05. Theory Division, CERN, CH-1211 Geneve 23, SWITZERLAND; e- mail keijo.kajantie@cern.ch; preprint also available at cond- mat@xxx.lanl.gov (#9704056). 74.20.De; 74.25.Dw; 64.60.-i; 11.15.Ha.
George Kastrinakis, "An Unconventional Fermi Liquid Model for the Optimally Doped and Overdoped Cuprate Superconductors." Department of Physics, Loomis Laboratory of Physics, University of Illinois at Urbana- Champaign, 1110 West Green Street, Urbana, IL 61801-3080; e-mail gk@alecto.physics.uiuc.edu; preprint also available at cond- mat@xxx.lanl.gov (#9703141).
B. Keimer, H. F. Fong, S. H. Lee, D. L. Milius, and I. A. Aksay, "Doping Dependence of the Magnetic Resonance Peak in YBa2Cu3O6+x." To be published in the 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 Physics, Princeton University, Princeton, NJ 08544.
Beom Jun Kim, Jeenu Kim, Sung Yong Park, and M. Y. Choi, "Quantum Phase Transitions in Superconducting Arrays with General Capacitance Matrices." Preprint #SNUTP 97-018; to be published in Phys. Rev. B. Department of Physics and Center for Theoretical Physics, Seoul National University, Seoul 151-742, KOREA; e-mail bjkim@phya.snu.ac.kr; preprint also available at cond-mat@xxx.lanl.gov (#9704176). 74.50.+r; 67.40.Db; 05.30.Jp.
Chan-Joong Kim, Ki-Baik-Kim, Il-Hyun Kuk, and Gye-Won Hong, "Fabrication and Properties of YBa2Cu3O7-d-Ag Composite Superconducting Wires by Plastic Extrusion Technique." To be published in J. Mater. Sci. Superconductivity Research Laboratory, Korea Atomic Energy Research Institute, P.O. Box 105, Yusung, Taejon, 305-600, SOUTH KOREA; telephone +82 42 868 8908; telefax +82 42 862 5496; e-mail cjkim2@nanum.kaeri.re.kr.
Chan-Joong Kim, Ki-Baik Kim, Hai-Woong Park, Il-Hyun Kuk, and Gye-Won Hong, "Three-Dimensional Shape of the Y2BaCuO5 Pattern in Melt-Textured Y-Ba-Cu-O Oxide." To be published in J. Mater. Sci. Superconductivity Research Laboratory, Korea Atomic Energy Research Institute, P.O. Box 105, Yusung, Taejon 305-600, SOUTH KOREA; telephone +82 42 868 8908; telefax +82 42 862 5496; e-mail cjkim2@nanum.kaeri.re.kr.
M. Kiuchi, K. Noguchi, T. Matsushita, T. Kato, T. Hikata, and K. Sato, "Scaling of Current-Voltage Curves in Superconducting Bi-2223 Silver- Sheathed Tape Wires." To be published in Physica C (in press). Department of Computer Science and Electronics, Kyushu Institute of Technology, 680-4 Kawazu, Iizuka 820, JAPAN.
N. B. Kopnin and G. E. Volovik, "Flux-Flow in d-Wave Superconductors: Low Temperature Universality and Scaling." Submitted to Phys. Rev. Lett. Landau Institute for Theoretical Physics, 117334 Moscow, RUSSIA; G. E. Volovik's e-mail at Helsinki, Finland volovik@boojum.hut.fi; preprint also available at cond-mat@xxx.lanl.gov (#9704184). 74.25.Fy; 74.25.Jb; 74.72.-h; 74.60.Ge.
W. Lang, G. Heine, W. Liebich, X. L. Wang, and X. Z. Wang, "Magnetoresistance in HTSC Far Above Tc: Fluctuations Versus Normal- State Contributions." To be published in Fluctuations in High Temperature Superconducting Ceramics, NATO-ASI Series, edited by M. Ausloos and A. Varlamov (Kluwer, Dordrecht, 1997). Ludwig Boltzmann Institut fuer Festkoerperphysik, Kopernikusgasse 15, A-1060 Wien, AUSTRIA; telephone +43 1 5863409 21; telefax +43 1 5863409 13; e-mail wolfgang.lang@univie.ac.at.
Hong Li, Wenxiu Zhu, Jinghui Cai, Pingsheng Zhang, Yuan Zhou, Aisheng He, Zhonglin Gong, Yusheng He, P. A. Smith, T. W. Button, J. E. Holmes, M. J. Lancaster, A. Porch, B. Avenhaus, P. Woodall, F. Wellhoefer, C. E. Gough, G. Kaiser, P. Seidel, and M. Thuerk, "Demonstration of HTS Microwave Subsystems with a Pulse Tube Cryocooler." 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. Cryogenic Laboratory, Chinese Academy of Sciences, Beijing 100080, PEOPLE'S REPUBLIC OF CHINA; P. Seidel's telephone in Germany +49 3641-635685 or -635681; telefax +49 3641-635681; e-mail seidel@ifk.uni-jena.de.
S. Linzen, J. Kraeusslich, A. Koehler, P. Seidel, B. Freitag, and W. Mader, "Unusual Crystal Structure of Nonsuperconducting Y1Ba2Cu3O7-x Films on Buffered Silicon Substrates." Institut fuer Festkoerperphysik, Freidrich-Schiller-Universitaet Jena, Max-Wien-Platz 1, D-07743 Jena, GERMANY; P. Seidel's telephone +49 3641-635685 or -635681; telefax +49 3641-635681; e-mail seidel@ifk.uni-jena.de. Key words: structure of thin films, HREM, YBCO, oxygen stoichiometry. 68.55.-a; 61.16.Bg; 74.72.Bk; 74.62.Bf.
R. S. Markiewicz, "Stripes, Pseudogaps, and Van Hove Nesting in the Three-Band tJ Model." Submitted to Phys. Rev. B. Department of Physics and Barnett Institute, Northeastern University, 111 Dana Research Center, Boston, MA 02115; telephone (617) 373-2902; telefax (617) 373- 2943; e-mail markiewic@neu.edu; preprint also available at cond- mat@xxx.lanl.gov (#9701227).
D. Mihailovic, "Two-Component High Tc Superconductivity: Charge Reservoirs, Phase Separation, and Optical Excitations." To be published in Proc. of the NATO Adv. Study Inst. on Materials Aspects of High-Tc Supercond.: 10 Years After the Discovery, Delphi, Greece, Aug. 19-31, 1996, edited by E. Liarokapis, E. Kaldis, and K. A. Mueller (Kluwer, Dordrecht). Jozef Stefan Institute, P.O. Box 3000, Jamova 39, 1001 Ljubljana, SLOVENIA; telephone +386 61-177 3729; telefax +386 61-125 1077, -219 385, or -123 5400; e-mail dragan.mihailovic@ijs.si.
D. Mihailovic and K. A. Mueller, "The Two-Component Paradigm for Superconductivity in the Cuprates." To be published in Proc. of the NATO Adv. Study Inst. on Materials Aspects of High-Tc Supercond.: 10 Years After the Discovery, Delphi, Greece, Aug. 19-31, 1996, edited by E. Liarokapis, E. Kaldis, and K. A. Mueller (Kluwer, Dordrecht). Jozef Stefan Institute, P.O. Box 3000, Jamova 39, 1001 Ljubljana, SLOVENIA; telephone +386 61-177 3729; telefax +386 61-125 1077, -219 385, or -123 5400; e-mail dragan.mihailovic@ijs.si.
D. Mihailovic, C. J. Stevens, B. Podobnik, J. Demsar, M. Zavrtanik, D. Smith, and J. F. Ryan, "Evidence for Two-Component Superconductivity in the Femtosecond Optical and Transient Photoconducting Response of YBa2Cu3O7-d." To be published in J. Supercond.: Proc. of the Int. Conf. on Stripes, Lattice Instabilities, and High Tc Supercond., Rome, Italy, Dec. 8-12, 1996. Jozef Stefan Institute, P.O. Box 3000, Jamova 39, 1001 Ljubljana, SLOVENIA; telephone +386 61-177 3729; telefax +386 61-125 1077, -219 385, or -123 5400; e-mail dragan.mihailovic@ijs.si.
A. S. Moskvin, "Origin of Unconventional Physical Behavior of Copper Oxide High-Tc Superconductors." To be published in Physica C. Department of Theoretical Physics, Ural State University, Lenin Ave. 51, 620083 Ekaterinburg, RUSSIA; e-mail alexandr.moskvin@usu.ru. Key words: copper oxides, Jahn-Teller effect, local pairing.
A. S. Moskvin, A. S. Ovchinnikov, and O. S. Kovalev, "Charge Fluctuations and Magnetic Inelastic Neutron Scattering in Copper-Oxide High-Tc Superconductors." To be published in Physica C. Department of Theoretical Physics, Ural State University, Lenin Ave. 51, 620083 Ekaterinburg, RUSSIA; e-mail alexandr.moskvin@usu.ru. Key words: copper oxides, singlet-triplet magnetic, induced spin fluctuations.
M. Muralidhar, H. S. Chauhan, T. Saitoh, K. Segawa, K. Kamada, and M. Murakami, "Application of Oxygen Controlled Melt Growth (OCMG) in Ternary RE123 Systems." 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. Superconductivity Research Laboratory, International Superconductivity Technology Center (ISTEC), 3-35-2 Iioka-Shinden, Morioka, Iwate 020, JAPAN; telephone +81 19 635-9015 or -9016; telefax +81 19 635-9017; e-mail miryala@istec.or.jp.
Amar Nath, Vladimir Chechersky, Zoltan Homonnay, and Attila Vertes, "Emission Mossbauer Effect Studies of Some Outstanding Problems in High Temperature Superconductivity." To be published in the Proc. of the Int. Workshop on High-Temp. Supercond.: Ten Years After its Discovery, Jaipur, India, Dec. 16-21, 1996, edited by S. M. Bose and K. B. Garg (Narosa Publishing House, New Delhi). Department of Chemistry, Drexel University, 32nd & Chestnut Streets, Philadelphia, PA 19104; telephone (215) 895-2648; telefax (215) 895-1265; e-mail amar_nath@coasmail.drexel.edu.
A. K. Nguyen and A. Sudbo, "Onsager Loop-Transition and First Order Flux-Line Lattice Melting in High-Tc Superconductors." Contact A. Sudbo, Department of Physics, Condensed Matter Theory Group, Norwegian University of Science and Technology, N-7034 Trondheim, NORWAY; telephone +47 73 59 34 03; telefax +47 73 59 36 28; e-mail asudbo@phys.unit.no.
Naoki Ohashi, Hiroshi Imagawa, Takaaki Tsurumi, and Osamu Fukunaga, "Phase Stability of Tetragonal SrCuO2-Type Compounds in the (Sr,Ca)CuO2 System." To be published in Physica C (in press). Department of Inorganic Materials, Faculty of Engineering, Tokyo Institute of Technology, 2-12-1 O-okayama, Meguro, Tokyo 152, JAPAN; telephone +81 3 573 42829; telefax +81 3 573 42514; e-mail nohashi@ceram.titech.ac.jp. Key words: SrCuO2, CaCuO2, high pressure, lattice constant.
Thomas Pe, Maamar Benkraouda, and John R. Clem, "Model Calculations for the Current-Voltage Characteristics of Moving Two-Dimensional Pancake Vortex Lattices in a Finite Stack of Magnetically Coupled Superconducting Thin Films with Transport Current in the Top Layer." Submitted to Phys. Rev B. Ames Laboratory-USDOE and Department of Physics and Astronomy, Iowa State University, Ames, IA 50011-3020; e- mail clem@ameslab.gov.
M. Ruebhausen, N. Dieckmann, K.-O. Subke, A. Bock, and U. Merkt, "Investigation of the Temperature, Resonance, and Symmetry Properties of the Spin-Fluctuation Intensity in Y0.8Pr0.2Ba2Cu3O7 Using Raman Spectroscopy." To be published in Physica C. Contact N. Dieckmann, Institut fuer Angewandte Physik, Universitaet Hamburg, Jungiusstrasse 11, D-20355 Hamburg, GERMANY; telephone +49 40 4123 4202; telefax +49 40 4123 4368; e-mail dieckmann@physnet.uni-hamburg.de. 78.30.Er; 75.30.Ds; 74.72.Jt.
S. V. Samoylenkov, O. Yu. Gorbenko, and A. R. Kaul, "An Analysis of Charge Carriers Distribution in RBa2Cu3O7 Using the Calculation of Bond Valence Sums." To be published in Physica C (in press). Contact O. Yu. Gorbenko, Department of Chemistry, Moscow State University, 119899 Moscow, RUSSIA; telephone +7 95 9391492; telefax +7 95 9390998; e-mail gorbenko@htsc.chem.msu.su. Key words: charge carriers, bond valence sum, RBa2Cu3O7.
D. R. Sanchez, H. Micklitz, and E. Baggio-Saitovitch, "Magnetic Structure of GdNi2B2C as Seen by the Transferred Magnetic Hyperfine Field at the Ni Site." To be published in J. Phys. Centro Brasileiro de Pesquisas Fisicas, Rua Xavier Sigaud 150 Urca, CEP 22290-180, Rio de Janeiro, BRAZIL.
I. Schildermans, M. Van Bael, E. Knaepen, J. Yperman, J. Mullens, and L. C. Van Poucke, "Synthesis of the High Temperature Superconductor YBa2Cu3O7-d by the Hydroxide Co-Precipitation Method." To be published in Physica C (in press). Laboratory of Inorganic and Physical Chemistry, Limburgs Universitair Centrum, B-3590 Diepenbeek, BELGIUM; telephone +32 1126 8393; telefax +32 1126 8301; e-mail ischilde@luc.ac.be. Key words: synthesis, co-precipitation, YBa2Cu3O7- d.
J. Schroeder, M. Ye, J. F. de Marneffe, M. Mehbod, R. Deltour, A.G.M. Jansen, and P. Wyder, "Thermally Activated Flux Motion in YBa2(Cu1- xZnx)3O7-d Epitaxial Thin Films: Influence of Magnetic Field and Zn Doping." To be published in Physica C (in press). Contact R. Deltour, Universite Libre de Bruxelles, CP 233, Bd. du Triomphe, B-1050 Bruxelles, BELGIUM; telephone +32 2 650 5752; telefax +32 2 650 5916; e- mail rdeltour@ulb.ac.be. Key words: high-Tc superconductor, thin film, pinning. 74.60.Ge; 74.60.Jg; 74.25.Fy; 74.76.Bz.
H. Shaked, A. Shames, L. Frenkel Ben-Yakar, S. Goren, B. Bandyopadhyay, G. Furman, C. Korn, C. Perrin, and P. Massiot, "Enhancement of Nuclear Quadrupole Resonance by Vortices in a Superconductor." Submitted to Phys. Rev. Lett. Department of Physics, Ben Gurion University, Beer- Sheva 84105, ISRAEL; S. Goren's telephone +972 7 6461171; telefax +972 7 6472903; e-mail shaulg@bgumail.bgu.ac.il. 74.25.Nf; 74.60.Ge; 74.72.Bk.
U. Staub, L. Soderholm, S. Skanthakumar, S. Rosenkranz, C. Ritter, and W. Kagunya, "Quasi Two-Dimensional Magnetic Order of Tb^[3+] Spins in Pb2Sr2Tb1-xCaxCu3O8 (x=0 and 0.5)." To be published in Z. Phys. B. Swiss Light Source Project, Paul Scherrer Institute, CH-5232 Villigen PSI, SWITZERLAND; telephone +41 56 310 4494; telefax +41 56 310 3151; e- mail urs.staub@psi.ch. 75.25.+z; 74.72.Jt; 76.30.Kg; 75.40.-s.
M. D. Sumption, L. R. Motowidlo, and E. W. Collings, "Determination of the True (or Potential) Transport-Jc of a Multifilamentary Bi:HTSC/Ag Strand in the Presence of Bridging and Generalized Sausaging." Submitted to Physica C. Department of Materials Science and Engineering, Ohio State University, Columbus, OH 43210. Key words: bridging, sausaging, critical currents, BSCCO.
L. Urba, C. Acha, and V. Bekeris, "Dissipation Mechanisms in Granular High Tc Superconductors." To be published in Physica C. Contact C. Acha, Laboratorio de Bajas Temperaturas, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Buenos Aires, Ciudad Universitaria, Pab. I, ARGENTINA; e-mail acha@df.uba.ar. Key words: magnetoresistance, I-V characteristics, flux-line lattice. 74.25.Fy; 74.40.+k; 74.60.Ge; 74.60.Jg.
G. E. Volovik, "From Effective BCS Action to Vortex Dynamics." To be published in Pis'ma ZhETF. Low Temperature Laboratory, Helsinki University of Technology, Otakaari 3A, 02150 Espoo, FINLAND; e-mail volovik@boojum.hut.fi; preprint also available at cond-mat@xxx.lanl.gov (#9703143).
R. Weinstein, R. P. Sawh, Y. R. Ren, J. X. Liu, and D. Parks, "Large Increases of Jc in Textured Bulk Y123 from Chemical and Radiation Effects of Uranium." Preprint #97:042; to be presented at the Third Joint ISTEC/MRS Int. Workshop on Supercond.: Suitable Materials and Processing for HTS Applications Towards the Next Decade, The Royal Waikoloan, Big Island, Hawaii, June 15-18, 1997. Beam Particle Dynamics Group and 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.
J. Z. Wu, B. W. Kang, W. N. Kang, S. H. Yun, A. Gapud, D. K. Christen, R. Kerchner, Q. Y. Chen, and W. K. Chu, "Sign Reversals in the Mixed- State Hall Effect of High-Tc Superconductors." Submitted to Phys. Rev. Lett. Department of Physics and Astronomy, University of Kansas, Lawrence, KS 66045; e-mail jwu@kuphsx.phsx.ukans.edu. 74.25.Fy; 74.60.Ec; 74.60.Ge.
Peidong Yang and Charles M. Lieber, "Nanorod/Tl2Ba2Ca2Cu3Ox Superconducting Composites." Department of Chemistry and Division of Applied Sciences, Harvard University, 12 Oxford Street, Cambridge, MA 02138; Charles M. Lieber's e-mail cml@cmliris.harvard.edu.
S. H. Yoo, K. W. Wong, and Y. Xin, "Thick Films of the Tl-Based Superconductor Fabricated via the Sol-Gel Technique." To be published in Physica C. Department of Physics and Astronomy, University of Kansas, Lawrence, KS 66045; e-mail kimyoo@kuphsx.phsx.ukans.edu. Key words: high-temperature superconductivity, thick film, Tl-based superconductor, synthesis. 74.76.Bz; 81.15.-z.
V. Zakosarenko, E. V. Il'ichev, R.P.J. Ijsselsteijn, and V. Schultze, "Current-Phase Relation of High-Tc Bicrystal and Step-Edge Josephson Junctions." Presented at the Appl. Supercond. Conf. (ASC'96), Pittsburgh, Pa., Aug. 25-30, 1996. Department of Cryoelectronics, Institute for Physical High Technology, P.O. Box 100239, D-07702 Jena, GERMANY.
Shou-Cheng Zhang, "The SO(5) Theory of High Tc Superconductivity." 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 Physics, Stanford University, Stanford, CA 94305; telephone (415) 723- 2894; telefax (415) 723-9389; e-mail sczhang@quantum.stanford.edu; Web site http://quantum.stanford.edu/sczhang; preprint also available at cond-mat@xxx.lanl.gov (#9704135).
A. A. Zhukov, G. K. Perkins, Y. V. Bugoslavsky, and A. D. Caplin, "Geometrical-Locking of the Irreversible Magnetic Moment to the Normal of a Thin Plate Superconductor." 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. 74.60.Ge; 74.72.Bk.
*June 8 - 13, 1997: 1997 IEEE MTT-S International Microwave Symposium, Denver, Colo. Will focus on highly integrated ICs or subsystems that include rf functions at any frequency. Will include session on superconducting microwave and millimeter-wave circuits and systems. Topics include: cryocooler overview, Stirling cooler, pulse-tube cooler, G-M cooler, J-T cooler, HTS device packaging, IR device packaging, wireless communication system, potential applications of superconductive systems for wireless communications, low-noise cryoelectronics, oscillators with ultra-low-phase noise, low-noise superconductive systems, filters for space application, and HTS for communications applications. For further information, contact Vijay Nair, Technical Program Chair; telephone (602) 413-5922; telefax (602) 413-5934; e-mail v.nair@ieee.org. Information also available at the Web site http://www.ieee.org/mtt/mtt.html.
*June 26 - 28, 1997: Sixth International Superconductive Electronics Conference (ISEC'97), Intercontinental Hotel, Berlin, Germany. Conference will encompass all aspects of superconductive electronics including the enabling technologies, devices, circuits, instrumentation, theory, and applications ranging from very-low-frequency SQUIDs to ultra-high-speed digital circuits. Of special interest will be the progress towards commercial products. Oral and poster sessions with no parallel sessions. Topics will include: physics of superconductive devices, superconducting device fabrication, process technology, superconductive digital and analog circuits and devices, new devices such as superconductive transistors and power devices, applications and instrumentation, and others. For further information, contact ISEC'97 Conference Secretariat, Dipl. Phys. Silvia Knappe, Physikalisch- Technische Bundesanstalt, Abbestr. 10-12, D-10587 Berlin, Germany; telefax +49 30 3481-490; e-mail isec97@ptb.de; Web site http://www.lab1033.berlin.ptb.de/10/102/isec97/start.htm.
Aug. 4 - 5, 1997: 1997 Space Cryogenics Workshop, Valley River Inn, Eugene, Oregon. Will follow the Cryogenic Engineering Conference (CEC 1997), to be held in Portland, Oreg. on July 27- Aug. 1, 1997. Topics will cover all aspects of space cryogenics with emphasis on space missions with cryocoolers, past and present astrophysical missions, and space cryogenic technology. Abstract deadline, June 5, 1997; early pre- registration deadline, June 30, 1997. For information, contact P. V. Mason, MS 79-24, Jet Propulsion Laboratory, Pasadena, CA 91109; telephone (818) 354-2300; e-mail spacecryo@squid.jpl.nasa.gov.
Aug. 25 - 28, 1997: International Conference on Computational Physics (PC '97), Santa Cruz, Calif. Meeting will be the first full conference sponsored by the American Physical Society's Division of Computational Physics and the Forum on Industrial and Applied Physics, and will be held jointly with the European Physical Society and the International Union of Pure and Applied Physics. Intends to facilitate interactions between developers and users of computational methods, and strongly emphasize applications of computational physics to industrial and other practical problems. Six tutorial sessions will cover applications and methods of computational physics in topic areas including fluid dynamics, optimization methods, object-oriented methods, and industrial physics, among others. Abstract deadline, May 16, 1997; registration deadline, July 15, 1997. Housing and registration forms available at the conference Web site at http://aps.org/meet/PC97/. Additional information regarding plenary and invited speakers, and Sunday tutorials will be added to the conference site as it becomes available. For information, contact Ann Lavallee, Conference Secretary, Department of Physics, University of California at Davis, Davis, CA 95616-8677; telephone (916) 752-4088; telefax (916) 752-4717; e-mail comp97@physics.ucdavis.edu; Web site http://aps.org/meet/PC97/.
*Sept. 1 - 12, 1997: NATO Advanced Study Institute on the Gap Symmetry and Fluctuations in High-Tc Superconductors, Institut d'Etudes Scientifiques de Cargese, Corse, France. Objective is to give advanced lectures on the most recent progress in understanding of the physics of high-temperature superconductors with a special emphasis on the symmetry of the superconducting gap and critical fluctuations. Pedagogical explanation of various theoretical models and a direct comparison with recent (often controversial) experiments is the central point of this Advanced Study Institute. For information, contact Davor Pavuna, Institute Micro- & Opto-electronique, Department de Physique - Ecole Polytechnique Federale, CH-1015 Lausanne, Switzerland; telephone +41 21- 6933301; telefax +41 21-6934666; e-mail pavuna@eldp.epfl.ch; Web site http://dpwww.epfl.ch/conferences/cargese97.html.
*Sept. 13 - 18, 1998: 1998 Applied Superconductivity Conference, MarriottUs 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.
Information
New Report: Chodendo -- Superconductivity Research in Japan, by Govind Pindoria and Tom Salusbury. A report from the Science & Technology Section, British Embassy, Tokyo. Intended for officials, academics, researchers, and industrialists who have an interest in superconductivity research and its applications to industry. This report reviews the considerable research effort that continues in Japan in both corporate and government institutes, and concentrates on the R&D programs of companies, universities and institutes, identifying the key advances and remaining challenges. Contents are: a brief introduction to superconductivity, superconductivity research in Japan, superconductivity research organizations, superconductivity developments in companies, and conclusions. Thirty-four pages of annexes give details of addresses and Internet home pages for most organizations. Publ. Feb. 1997; 55 pp. For copies of the report, contact G. Pindoria, NEDO Research Fellow, Superconductivity Research Laboratory, International Superconductivity Technology Center, 1-10-13 Shinonome, Koto-ku, Tokyo 135, JAPAN; telephone +81 3 3536 5713; telefax +81 3 3536 5717; e-mail pindoria@istec.or.jp or govind@inJapan.net.
Online Journal: Solid State Communications is now online, and a three- month free trial subscription of this new service is available through your institution library. For information, visit the Web site http://www.elsevier.com/locate/ssconline or contact D. Prosser at e-mail d.prosser@ elsevier.co.uk.
HTS Web Sites: The National Center for Magnetic Measurements and the Institute for Super-conductivity at the Bar-Ilan University, Israel, invite you to visit their Web page at http://www.biu.ac.il/NAT/htslab/ or http://htslab.ph.biu.ac.il. Information on recent publications, ongoing projects, facilities, and personnel available at this site.
The International Energy Agency (IEA) implements a high-temperature superconductivity agreement that provides a forum for the exchange of information and collaborative assessment of the impact of advances in high-temperature superconductivity on the electric power sector. The relevant home page is located at http://www.iea.org/impagr/imporg/effene/a31htsup.htm.
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, #10, May 15, 1997.