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Bi Cuprates
Remarkable details from scanning tunneling microscope (STM) studies of the effects on high-temperature superconductivity of individual impurity atoms substituted at the Cu site in the CuO2 plane of Bi2Sr2CaCu2O8+d (Bi-2212) are reported by S. H. Pan (UC-Berkeley) et al. When the STM tip was placed above an ordinary superconducting region of the sample, the differential conductance exhibited behavior consistent with d-wave superconductivity, with sharp gap peaks at roughly +-40 mV. However, when the STM tip was placed directly over any Zn impurity, the differential conductance showed an intense quasiparticle resonance (at Omega = -1.5+-0.5 mV) with a peak up to six times greater than the normal-state conductance, while both the gap and the height of the differential conductance at the gap were strongly suppressed. The authors found the sharp resonance peaks to be consistent with unitary scattering in a d-wave superconductor. Imaging of the local density of states at the resonance energy revealed a highly localized quasiparticle cloud with clear four-fold symmetry aligned with the d-wave gap nodes, in qualitative agreement with theory. The authors report other observations that directly validate the deductions of a variety of previous theoretical and experimental studies. The authors also found new phenomena, which cannot be explained by existing theories and thus should provide new information about high-temperature superconductivity at the atomic scale.
The gradient of the energy-integrated angle-resolved photoemission (ARPES) intensity has been used by J. Mesot (Argonne and UI-Chicago) et al. to determine the Fermi surface in Bi-2212. The authors show that, independent of the photon energy, the Fermi surface is a hole barrel centered at (pi,pi). The authors determined the superconducting gap along the Fermi surface in overdoped and underdoped samples of Bi-2212. As the doping increases, they found that the maximum gap increases but the slope of the gap near the nodes decreases. Though consistent with d-wave symmetry, the gap with underdoping cannot be fit by the simple cos k_x - cos k_y form. A comparison of the ARPES data with available penetration-depth data indicates that the renormalization of the linear T suppression of the superfluid density at low temperatures due to quasiparticle excitations around the d-wave nodes is large and doping dependent.
Atomically clean Bi-2212 Josephson junctions between identical single crystals, prepared by cleaving, twisting by an angle phi_0 about the c axis, and stacking, have been prepared by Q. Li (Brookhaven) et al. For each bicrystal, the ratio Jc^J/Jc^S of the c-axis twist junction (J) critical current density to that across either single crystal (S) at 0.9 Tc was found to be very nearly unity, independent of phi_0 and the ratio A^J/A^S of the junction area to the single-crystal cross-sectional area. The authors assert that their results provide strong evidence for incoherent c-axis tunneling and that the dominant superconducting order parameter near Tc contains an isotropic s-wave component but not a d_[x^2-y^2] component. The authors note, however, that the data do not rule out a second, unobserved phase transition to a d-wave state at another critical temperature below Tc.
Anomalous features in the normal-state resistivity of single-crystalline Bi-2212 whiskers near T* ~ 250 K are reported by W. Chen et al. (Alberta). The authors interpret the features as being related to a crystal-structure transformation (or lattice distortion), as also observed in thermal and elastic property measurements.
Flux pinning in heavily Pb-doped Bi-2212 crystals (Bi2-xPbxSr2CaCu2Oy) has been studied by J. Horvat et al. (Wollongong). In samples for which the atomic ratio of Bi to Pb atoms was 1.66:0.34, the magnetic hysteresis loops exhibited a pronounced secondary peak effect in the temperature range 20 K < T < Tc, yielding critical current densities Jc several times higher than for pure Bi-2212. The authors suggest that enhanced c-axis coupling upon Pb doping contributes to the increased pinning in both low and high fields, while nanometer-size amorphous regions are probably responsible for the increased pinning at higher fields.
RBa2Cu3O7-d
Hydrostatic high-pressure studies to 17 GPa on superconducting YBa2Cu3Ox (Y-123) over the full range of oxygen content x have been carried out by S. Sadewasser (Washington University) et al. The observed bell-shaped Tc(P) dependencies were found to depend markedly upon the temperature at which the pressure was changed. The authors studied time-dependent relaxation processes using both Tc and the electrical resistivity at 298 K as probes, and they determined the activation volume for oxygen diffusion from the pressure-dependent activation energy and compared this with estimates from a simple hard-sphere model.
Disks of Y-123 have been prepared by H. Fang and K. Ravi-Chandar (TCSUH) using a new seeded infiltration and growth process. The critical current density at 77 K was found to be in excess of 10^5 A/cm^2 in zero field and 2 x 10^4 A/cm^2 in 1.5 T, suggesting that this method is a good alternative to the melt-texturing process.
YBa2Cu3O7-d-Ba2HoSbO6 superconductor-ceramic insulator composites have been studied by J. Albino Aguiar (Recife) et al. The authors found that the two components coexist with no detectable interactions between the two phases.
Large, single-grain NdBa2Cu3O7-d (Nd-123) - Nd4Ba2Cu2O10 (Nd-422) composites up to 2 cm in diameter have been fabricated by N. Hari Babu et al. (IRC-Cambridge) using a top-seeded melt-growth technique in a controlled 1% O2 in N2 atmosphere. An exceptionally high irreversibility field (>12 T at 89 K) was observed in this material for a magnetic field applied perpendicular to the c axis, extrapolating to well over 40 T at 77 K.
Single crystals of Nd-123 have been grown by S. Shibata et al. (SRL- ISTEC) using a horizontal Bridgman-like method under various partial O2 pressures (0.04-0.1%) in an Ar atmosphere. The authors obtained high- quality Nd-123 single crystals with Tc = 95.0 K using YSZ boats. An increase of the magnetization with increasing field (i.e., a fishtail or peak effect) was observed around 77 K in magnetic fields parallel to the c axis for crystals grown under 0.06-0.1% O2 partial pressures but not for crystals grown under 0.04 and 0.05% O2 pressures. Since the amount of Nd substitution on the Ba site is reduced with decreasing O2 pressure, the results support the hypothesis that the peak effect in Nd- 123 is due primarily to Nd/Ba substitution.
RuSr2GdCu2O8
RuSr2GdCu2O8 (Ru-1212) is a triple perovskite containing both CuO2 and RuO2 layers. As noted by J. E. McCrone (IRC-Cambridge) et al., it has attracted much recent interest because it displays electronic ferromagnetism (T_[Curie] ~ 135 K) and superconductivity (Tc up to 50 K) coexisting on a microscopic scale. The authors report magnetization and magnetoresistance data that exhibit effects due to the interaction between the ferromagnetic Ru moments and the conduction electrons. An analysis of the high-temperature data in terms of spin-disorder- scattering theory yields a value for the exchange interaction between the Ru spins and the carriers in the CuO2 planes.
Relying on the inhomogeneous (layered) crystal, electronic, and magnetic structure, W. E. Pickett (UC-Davis) et al. show theoretically how superconductivity can coexist with the ferromagnetic phase of RuSr2GdCu2O8, as observed by Tallon and co-workers. Since the Cu d_[x^2-y^2] orbitals couple only weakly to apical O p_x,p_y orbitals, which also couple only weakly to the magnetic Ru t_[2g] orbitals, there is sufficiently weak exchange splitting, especially of the symmetric CuO2 bilayer Fermi surface, to allow singlet pairing. The authors find that the exchange splitting is large enough that the superconducting order parameter may be of the Fulde-Ferrell-Larkin-Ovchinnikov type. The authors also note that pi-phase formation is preferred by the magnetic characteristics of RuSr2GdCu2O8.
The crystal and magnetic structure of a sample of RuSr2[160]^GdCu2O8 that orders magnetically at 133 K and exhibits a superconducting transition at 35 K has been determined by O. Chmaissem (Northern Illinois and Argonne) et al. using neutron powder diffraction. The only structural parameters that respond to the magnetic ordering at 133 K are the Cu-Cu distance, which defines the thickness of the CuO2 double layer, and the buckling angle of the CuO2 planes. Magnetic scattering consistent with the previously proposed ferromagnetic ordering of Ru moments perpendicular to the c axis was not observed, but the authors do not rule out ordering of Ru moments parallel to the c axis or itinerant ferromagnetism.
Other Cuprates
NQR [139]^La and [63]^Cu spin-lattice relaxation rate (1/T_1) measurements in a La1.94Sr0.06CuO4 single crystal are described in a preprint by M.-H. Julien (Pavia and Ames Lab-Iowa State) et al. The slowing down of Cu^[2+] spin fluctuations was evidenced by a dramatic increase of 1/[139]^T_1 on cooling. This and other results show that the so-called cluster spin-glass phase persists in the superconducting regime.
In all previously investigated samples of La2-xAxCu1-zBzO4+y (A = Sr or Nd, B = Zn) including high-Tc superconductors and insulators, and in bilayered superconducting YBa2Cu3O6.6 and Bi2Sr2CaCu2O8+d, when sufficient numbers of holes are introduced into the two-dimensional CuO2 square lattice, dynamic magnetic correlations become incommensurate with the underlying lattice. Magnetic correlations also become incommensurate in structurally related La2NiO4 when doped with Sr or O. However, W. Bao (LANL) et al. have found an exception to this rule in La2Cu1-zLizO4, in which the magnetic correlations remain commensurate.
The results of Raman-scattering experiments on single crystals of La2- xSrxCuO4 as a function of temperature and doping are reported by J. G. Naeini (Simon Fraser) et al. The authors use the extended Drude model (memory function formalism) and a Kramers-Kronig transformation to obtain the temperature- and frequency-dependent scattering rate from the B_[2g] Raman response function. Comparison with results from other techniques provides a consistent picture of the pseudogap in La2- xSrxCuO4 and evidence for the existence of cold spots near (+-pi/2,+- pi/2).
Two preprints by A. J. Zaleski and J. Klamut (Wroclaw) present results for the anisotropy and the temperature dependence of the penetration depth in magnetically oriented, powdered La2-xSrxCu1-yZnyO4. The results seem to support Uemura's picture of a crossover from Bose- Einstein to BCS-like condensation in high-temperature superconductors.
Hydrostatic pressure effects on the superconducting transition temperature Tc of the oxycarbonate cuprates (Cu0.5C0.5)Ba2Cam-1CumOx [(Cu,C)-12(m-1)m] have been determined by Y. Cao et al. (TCSUH) for m = 3 and 4 with different dopings of x. In (Cu,C)-1223, the authors found behavior similar to that of YBa2Cu3O7-d, in that dTc/dP depends strongly on x, increasing from -0.7 K/GPa to +1.2 K/GPa as x decreases and the compound changes from overdoped to nearly optimally doped, consistent with the prediction of a phenomenological model for the pressure effect on Tc. In (Cu,C)-1234, however, contrary to the prediction, dTc/dP depends only slightly on x and decreases from 0.75 K/GPa to 0.6 K/GPa as x decreases from nearly optimally doped to underdoped.
Vortices
A layered superconductor in a magnetic field of arbitrary orientation with respect to the conducting plane has been considered by U. Klein (Linz) et al. The authors find that there is competition of Pauli spin- pair-breaking effects, favoring the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state, and orbital-pair-breaking effects, favoring the Abrikosov vortex phase. The authors calculate the actual structure of the stable states below H_[c2] by minimizing the free energy, and they find new order-parameter structures that differ from both the traditional Abrikosov and FFLO solutions. These include two-dimensional periodic structures with several zeros of the order parameter and quasi-one- dimensional structures consisting of vortex chains separated by FFLO domains.
An extensive theoretical study of vortex physics in confined geometries is reported in a paper by M. C. Marchetti and D. R. Nelson (Harvard). The authors discuss properties of vortex liquids in cuprate superconductors with columnar defects. Experiments that force the vortices to flow in confined geometries can be used to distinguish between continuous disorder-driven glass transitions of vortex matter, such as the vortex-glass or the Bose-glass transition, and nonequilibrium polymer-like glass transitions driven by interaction and entanglement. The authors discuss, for example, how the critical exponents for all six vortex liquid viscosities can be obtained.
A paper by G. W. Crabtree (Argonne) et al. describes transport experiments that probe the dynamic nature of driven vortex motion. An inhomogeneous Lorentz driving force is applied to the sample, inducing vortex velocity gradients that distinguish hydrodynamic motion of the vortex liquid from the elastic and plastic motion of the vortex solid. The authors observed elastic depinning of the vortex lattice at the critical current, and shear-induced plastic slip of the lattice at high Lorentz-force gradients.
Vortex-glass transitions induced by line-like disorder, the so-called Bose-glass transition and two types of Gaussian-splayed-glass transitions, have been studied by R. Ikeda (Kyoto) using the lowest- Landau-level approach to the Ginzburg-Landau model. For each of these transitions, the author estimates the transition point and derives critical properties of the response properties just above the transition.
The gradual evolution of the first-order vortex-melting transition into a continuous transition with the systematic addition of point disorder in YBa2Cu3O7-d induced by proton irradiation is described in an experimental paper by L. M. Paulius (Western Michigan and Argonne) et al. The evolution occurs via the decrease of the upper critical point and the increase of the lower critical point. The first-order melting transition occurs when the two critical points merge.
The upper and lower critical points in untwinned YBa2Cu3O7-d crystals with dilute columnar defects have been investigated experimentally by W. K. Kwok (Argonne) et al. The authors find a convergence of the first- order melting line with a second-order Bose-glass line at the lower critical point. The lower critical point increases with columnar defect density. The columnar defects also raise the upper critical point, indicating that vortex-line meandering is a basic feature controlling its position.
Preprints by C. Boekema (San Jose State) et al. and by R. Santiago (San Jose State) et al. report muSR studies of the magnetic-field distributions in the vortex state of cuprate superconductors. The data show evidence for d-wave superconductivity. The authors make extensive use of the maximum-entropy method to analyze the muSR time-series data.
A preprint by A. Buzdin and M. Daumens (Bordeaux) shows how when defects are smaller than the London penetration depth, vortex pinning interactions can be calculated conveniently by making use of analogies to related electrostatic problems.
The magnetic response of type-II superconductors as influenced by both bulk pinning and geometric edge barriers has been thoroughly analyzed by E. H. Brandt (MPI-Stuttgart). The author stresses that even without bulk pinning and in the absence of a microscopic Bean-Livingston surface barrier for vortex penetration, superconductors of nonellipsoidal shape can exhibit a large geometric barrier for flux penetration. The author gives expressions for the first-flux-entry field H_[en] and the irreversibility field H_[rev].
The competing roles of weak residual bulk pinning, and surface and geometrical barrier effects in YNi2B2C, as measured using micro-Hall probes, are discussed in a paper by S. S. James (IRC-Cambridge) et al.
A high-resolution scanning Hall probe microscope (1-2 micrometers spatial resolution and 30 mG field sensitivity) has been used by S. S. James (Colorado State and IRC-Cambridge) to study dendritic magnetic flux penetration into thin Nb strips in a slowly ramped applied field. The dendritic fingers persisted over all temperatures investigated from 0.3 to 0.95 Tc.
Films
The epitaxial growth and properties of Nd1+xBa2-xCu3O7-d (NBCO) thin films deposited using pulsed-laser deposition (PLD) are reported by C. Cantoni et al. (Oak Ridge). Thin films with T_[c0] = 93 K and Jc(H = 0, T= 77 K) = 3 x 10^6 A/cm^2 were reproducibly fabricated on single- crystal LaAlO3 substrates. NBCO films also were grown on textured Ni substrates on which a YSZ/CeO2 buffer-layer architecture was previously deposited by the same PLD technique. Microstructural analysis revealed a high degree of in-plane and out-of-plane alignment for the different layers, as well as a dense morphology and low-angle grain boundaries (<=3 degrees) for the NBCO films. Direct current transport measurements yielded a Jc(H = 0, T= 77 K) = 3 x 10^5 A/cm^2. However, at high fields (>7 T), the Jc of the NBCO films on YSZ/CeO2/Ni substrates exceeded the Jc of both YBCO and NBCO films on LaAlO3.
As reported by J. Lesueur (Orsay), in-situ [110] and [103]YBCO/Pb junctions have been made. Both show a Josephson current and Andreev bound states, but the authors have not yet seen any evidence of coupling between them. In the [110] case, the Andreev bound states are split by a surface-induced state that breaks time-reversal symmetry. The asymmetric splitting remains to be explained.
A systematic study of the charge transport and quasiparticle tunneling properties of Y1-xPrxBa2Cu3O7-d thin films has been carried out by M. Covington and L. H. Greene (Illinois-Urbana-Champaign). Pr doping increases the resistivity along the CuO2 planes and suppresses Tc, ultimately inducing a superconductor-insulator transition. The tunneling conductance is reproducible and correlated with the crystallographic film orientation.
The absolute values of the normal-state conductivity sigma_n and the low-temperature penetration depth lambda(0) have been measured by A. Pimenov (Augsburg) et al. for a number of different YBa2Cu3O7-d films. The authors found a strong correlation between sigma_n and lambda^[-2] for different doping, oxygen reduction, and defect density, indicating that measurements of the normal-state conductivity can be used to predict the superconducting penetration depth and estimate the sample quality.
Experiments by B. J. Joensson-Akerman (Royal Institute of Technology- Stockholm) et al. have confirmed a recently proposed scaling relation for the nonlinear ac susceptibility response of type-II superconductors via high-precision measurements on a c-axis-oriented HgBa2CaCu2O6+d (Hg- 1212) thin film.
A preprint by B. Guettler (PTB-Braunschweig) et al. reports that micro- Raman spectrometry can be used to detect BaCu3O4 as an impurity phase in RBa2Cu3O7-d thin films with a mole fraction less than 1%, a sensitivity that exceeds that of x-ray diffraction by at least an order of magnitude.
Low-temperature measurements of the resistance of superconducting ultrathin amorphous Bi films in a magnetic field have been carried out by J. A. Chervenak and J. M. Valles, Jr. (Brown). The authors found that in films for which the normal-state sheet resistance R_N exceeds the resistance quantum, R_Q = h/e^2, there is no vortex solid and hence no zero-resistance state in a magnetic field.
Applications
The design and realization of an all-high-Tc dc superconducting quantum interference device (dc SQUID) are reported in a preprint by R. R. Schulz (Augsburg) et al. The device was realized with thin-film technology, in which the Josephson junctions consist of one standard junction (0-junction) and one junction with a pi phase shift (pi- junction). The authors compare the characteristics of the pi-SQUID with those of a standard high-Tc SQUID.
The development and testing of a 100 kVA superconducting transformer made of (Bi,Pb)-2223/Ag tapes and operated at 77 K are described in a preprint by P. Kummeth (Siemens-Erlangen) et al. The authors note that high-temperature superconducting (HTS) transformers are promising candidates for applications in electrical power engineering because of their advantages in reduced size and weight, better efficiency, and reduced fire and environmental hazards. The nominal primary and secondary currents and voltages were 18 A and 5.6 kV, and 91 A and 1.1 kV, respectively. No-load tests, short-circuit tests, and load tests proved repeatedly that the transformer had the rated capacity. HTS winding losses of 20.6 W and iron losses of 403 W were measured.
As reported in a preprint by J. Denul (Ghent) et al., ten partners from six European countries are collaborating in the industrial Brite EuRam project MUST, which stands for multifunctional flexible high-temperature superconducting tape. The objective is to develop a cost-effective tape with Jc in the superconducting film greater than 10^6 A/cm^2 at 77 K and 0 T, using high-power sputter deposition of 0.5-1 micrometer thick YBCO films on metallic and polymer substrates. The end product will be required to withstand stresses in operation while maintaining the desired characteristics of the superconducting state. The collaborators will demonstrate commercial possibilities of this tape by the fabrication of components suitable for MRI applications, fault-current limiters, and a high-field HTS magnet (B > 2 T). Two preprints by I. Van Driessche (Ghent) et al. report related progress in the development of magnetron sputtering techniques for the deposition of YBCO.
Transport losses in multifilamentary (Bi,Pb)-2223/Ag tapes with different filament arrangements have been measured by M. Majoros (IRC- Cambridge and Bratislava) et al. The samples were untwisted and had seven filaments, which were arranged in columns, in slanted columns, or evenly distributed across the tape cross section. The authors found that the sample with filaments stacked in columns had slightly lower normalized losses at low normalized currents (I_0/I_c < 0.2) but that there was no difference in the loss data for the three different filament geometries in the range I_0/I_c > 0.2.
Theory
The critical properties of a type-II superconductor have been investigated by J. Hove and A. Sudbo (Trondheim) using a vortex representation. Computing the gauge-field and the dual gauge-field propagators in terms of a vortex correlation function, the authors obtained eta_A = 1 and eta_h = 1 for the anomalous dimensions of both the gauge-field A and the dual gauge-field h. This provides support for a proposed dual description of the Ginzburg-Landau theory of type-II superconductors in the continuum limit, as well as for the existence of a stable charged fixed point of the theory, not in the 3DXY universality class.
The influence of a normal-state pseudogap on the c-axis and ab-plane conductivity has been investigated by T. Dahm (Dresden) et al. for spin- fluctuation-exchange scattering within the self-consistent FLEX (fluctuation-exchange) approximation. The authors find that coherent conductance can describe the c-axis conductivity in overdoped compounds, but incoherent c-axis conductance is necessary to describe the underdoped regime.
>From the phase diagram of the nearly half-filled single-band two- dimensional Hubbard model, H. Kondo and T. Moriya (Science University of Tokyo) discuss the possibility of the spin-fluctuation mechanism being the common origin of superconductivity in the high-Tc cuprates and 2D organic compounds.
An approach to study the competition of d_[x^2-y^2] and other subdominant complex symmetries of the gap function is proposed in a preprint by E.V.L. de Mello (Niteroi). The author notes that the results may be useful to interpret some experimental data and to explain why similar experiments yield different gap symmetries.
The formation of charge domain walls in an electron-doped extended Hubbard model for the superconducting cuprates has been investigated by A. Sadori and M. Grilli (Roma). Within an unrestricted Hartree-Fock approach, extended by the introduction of slave bosons to account for strong correlations, the authors demonstrate the occurrence of stripes in the (1,1) and (1,-1) directions having one doped electron per stripe site.
A simple BCS-like model that describes unconventional superconductivity on the basis of an electron-electron attraction corresponding to a delta-shell potential has been studied by J. Quintanilla and B. L. Gyoerffy (Bristol). The authors obtain a Tc vs doping behavior similar to that found in the high-Tc cuprates.
A fermion-boson binary mixture of unpaired electrons coexisting and interacting with Cooper pairs treated as real two-electron or two-hole bosons is proposed by V. V. Tolmachev (Moscow) as a model of superconductivity. In thermodynamic equilibrium some of these bosons are Bose-Einstein-condensed at low enough temperature.
The evolution of the neutron cross section with variable frequency omega and fixed T below Tc has been studied by Y. J. Kao (Chicago) et al. in two cuprate families. Among other findings reasonably consistent with experiments, the authors see (a) peak sharpening below Tc in La2- xSrxCuO4, (b) a continuous decrease in incommensurability as the resonance at ~~ 2[Delta] is approached in YBa2Cu3O7-d, and (c) the re- emergence of incommensurate peaks above the resonance frequency.
A microscopic theory for the coupling of intrinsic Josephson oscillations in layered superconductors with longitudinal c-axis phonons has been developed by Ch. Helm et al. (Regensburg). Resonances in the I-V characteristics appear at Van Hove singularities of both acoustic and optical longitudinal phonon frequencies. The theory is able to explain experimentally observed low-frequency structures which previously were not understood.
Results of numerical calculations of the (H,T) phase diagram for a thin superconducting film with an elliptic hole (antidot) are presented in a preprint by C. Meyers et al. (Bordeaux). The critical field exhibits an oscillatory behavior as a function of the magnetic field through the antidot.
Other Activities
The Josephson coupling between a conventional s-wave superconductor (In) and Sr2RuO4 has been studied theoretically by R. Jin (Penn State) et al. The authors find that the coupling is allowed in the in-plane direction but not along the c axis.
The nature of the room-temperature crystal structure distortions in Sr3Ru2O7 has been studied by H. Shaked (Argonne) et al. The authors found that among the eight possible pure rotations of the oxygen octahedra, only one mode is consistent with the neutron data: rotation of the octahedra about the c axis. The resulting symmetry of the structure is orthorhombic.
The effects of the superconducting pair potential on impurity scattering processes in metallic carbon nanotubes have been studied theoretically by K. Harigaya (ETL and Kanazawa Institute of Technology). The author discusses the proximity effect when superconducting electrodes are connected by carbon nanotubes.
Thesis
The Geneve habilitation thesis of A. Erb summarizes the author's work over the last five years, including the development of BaZrO3 crucibles for the crystal growth of 123 compounds, measurements of oxygen diffusion coefficients during the oxygenation of single crystals of different 123 compounds, and an extensive study concerning the origin of the fishtail effect in YBCO and other rare-earth 123 compounds. The author discusses the influence of microstructural inhomogeneities on proposed vortex phase diagrams and the question of superconductivity in the Pr-Ba-Cu-O system, which is still a controversial subject (124 refs.).
Contributed by John R. Clem
Contents: Preprints begin on page 7; Coming Events are on page 13; FYI is on page 13, your comments are on page 14; and Donors are listed on page 15.
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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. Albino Aguiar, C. C. de Souza Silva, Y. P. Yadava, D. A. Landinez Tellez, J. M. Ferreira, E. Montarroyos, J. Guzman, and E. Chavira, "EDX Analysis and Microstructural Properties of the YBa2Cu3O7-d-Ba2HoSbO6 Superconducting Composites." To be published in J. Low Temp. Phys. Laboratorio de Supercondutividade, Departamento de Fisica, Universidade Federal de Pernambuco, Av. Prof. Luiz de Barros Freire s/n, 50670-901 Recife-PE, BRAZIL; telephone +55 81 271 8450; telefax +55 81 271 0359; e-mail albino@npd.ufpe.br. 74.60.-w; 74.62.Bf; 74.90.+n.
J. Albino Aguiar, David A. Landinez Tellez, Yogendra P. Yadava, J. M. Ferreira, E. Montarroyos, J. Guzman, and E. Chavira, "Structural and Superconducting Properties of the LaBaCaCu3O7-d-Ba2HoHfO5.5." To be published in Physica B. Laboratorio de Supercondutividade, Departamento de Fisica, Universidade Federal de Pernambuco, Av. Prof. Luiz de Barros Freire s/n, 50670-901 Recife-PE, BRAZIL; telephone +55 81 271 8450; telefax +55 81 271 0359; e-mail albino@npd.ufpe.br. Key words: LaBaCaCu3O7-d, Ba2HoHfO5.5, superconductor, composite.
S. Arul Antony, K. S. Nagaraja, S. Sahasranaman, and O. M. Sreedharan, "Complete Chemical Control of Stoichiometry of Materials Related to High Tc Ceramics RBa2Cu3O7-x (R=Rare Earth)." To be published in Physica C (in press). Contact O. M. Sreedharan, Materials Characterisation Group, Thermodynamics and Kinetics Division, Indira Gandhi Centre for Atomic Research, Kalpakkam, Tamil Nadu-603 102, INDIA; telephone +91 4114 40202; telefax +91 4114 40360; e-mail oms@igcar.ernet.in. Key words: complexometric titration, complete cation and oxygen analysis in rare earth 123.
N. Hari Babu, W. Lo, D. A. Cardwell, and A. M. Campbell, "The Irreversibility Behavior of NdBaCuO Fabricated by Top-Seeded Melt Processing." Preprint #L99-1441; to be published in Appl. Phys. Lett. Interdisciplinary Research Centre in Superconductivity, University of Cambridge, Madingley Road, Cambridge CB3 0HE, UNITED KINGDOM; D. A. Cardwell's telephone +44 1223-337050 or -337076; telefax +44 1223- 337074; e-mail dc135@hermes.cam.ac.uk.
Wei Bao, R. J. McQueeney, R. Heffner, J. L. Sarrao, P. Dai, and J. L. Zarestky, "Commensurate Dynamic Magnetic Correlations in La2Cu0.9Li0.1O4." Los Alamos National Laboratory, Los Alamos, NM 87545; e-mail bao@mozi.mst.lanl.gov; preprint also available at http://xxx.lanl.gov/abs/cond-mat/9909256.
C. Boekema, A. Childers, A. Krupski, R. Santiago, D. W. Cooke, and D. E. Farrell, "Maximum-Entropy muSR Study of R1237 Vortex States." Submitted to Physica B: Proc. of the 8th Int. muSR3 Conf. (CH'99). National High Magnetic Field Laboratory, Florida State University, 1800 East Paul Dirac Drive, Tallahassee, FL 32310; e-mail boekemac@aol.com. Key words: R1237, vortex, d-wave, cuprate superconductivity.
Ernst Helmut Brandt, "Superconductors in Realistic Geometries: Geometric Edge Barrier Versus Pinning." Submitted to the Proc. of the First Euroconf. on Vortex Matter in Superconductors, Crete, Greece, Sept. 18-24, 1999; to be published in Physica C. Max Planck Institut fuer Metallforschung, D-70506 Stuttgart, GERMANY. 74.60.Ec; 74.60.Ge; 74.55.+h.
E. Bruneel, A. J. Ramirez-Cuesta, I. Van Driessche, and S. Hoste, "A Model for the Percolation Effect in the Magnetic Susceptibility of HTSC Composites." To be published in the Proc. of the Fourth European Conf. on Appl. Supercond. (EUCAS'99), Barcelona, Spain, Sept. 14-17, 1999. Department of Inorganic and Physical Chemistry, Solid State and Superconducting Materials Division, University of Ghent, Krijgslaan 281 (S3), B-9000 Ghent, BELGIUM; telephone +32 9 264 4440; telefax +32 9 264 4983; e-mail els.bruneel@rug.ac.be.
A. Buzdin and M. Daumens, "Electrostatic Analogies in the Problems of Vortex-Defect Interaction." Submitted to Physica C. Centre de Physique Theorique et de Modelisation, Universite Bordeaux I, CNRS-ERS 2120, F- 33405 Talence Cedex, FRANCE; telephone +33 5 5796 2502; telefax +33 5 5796 2501; e-mail buzdin@pth.u-bordeaux.fr. Key words: vortex, pinning, entrance field, anisotropic superconductor. 74.60.Ec; 74.80.Dm.
C. Cantoni, D. P. Norton, D. K. Christen, A. Goyal, D. M. Kroeger, D. T. Verebelyi, and M. Paranthaman, "Transport and Structural Characterization of Epitaxial Nd1+xBa2-xCu3Oy Thin Films Grown on LaAlO3 and Ni Metal Substrates by Pulsed-Laser Deposition." To be published in Physica C. Solid State Division, MS-6061, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN 37831-6061; telephone (423) 574-6264; telefax (423) 574-6263; e-mail vkc@ornl.gov. Key words: Nd- 123, applications of high-Tc superconductors, grain alignment (texturing), thin films. 74.72.Jt; 74.62.Dh; 85.25.Kx; 68.55.Jk; 74.60.Jg.
Y. Cao, Z. L. Du, Y. Y. Xue, and C. W. Chu, "(Cu0.5C0.5)Ba2Cam-1CumOx for m = 3 and 4 Under Hydrostatic Pressures." Preprint #99:071; submitted to Phys. Rev. B. Microsoft Corp., 1 Microsoft Way, Redmond, WA 98052-6399; preprint also available from 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. 74.72.Jt; 74.62.Fj.
Weimin Chen, J. P. Franck, and J. Jung, "Evidence of Structural Instability Near T* ~ 250 K in the Resistivity of Bi2Sr2CaCu2O8 Whiskers." Submitted to Phys. Rev. B. Contact J. P. Franck, Department of Physics, University of Alberta, Edmonton, Alberta, CANADA T6G 2J1; e- mail franck@phys.ualberta.ca; preprint also available at http://xxx.lanl.gov/abs/cond-mat/9906079. 74.25.Fy; 74.72.Hs; 75.30.Kz.
J. A. Chervenak and J. M. Valles, Jr., "Absence of a Zero Temperature Vortex Solid Phase in Strongly Disordered Superconducting Bi Films." Department of Physics, Brown University, Providence, RI 02912; J. M. Valles, Jr.'s e-mail valles@physics.brown.edu; preprint also available at http://xxx.lanl.gov/abs/cond-mat/9909329. 74.40.+k; 73.23.-b; 74.60.Ge.
O. Chmaissem, J. D. Jorgensen, H. Shaked, P. Dollar, and J. L. Tallon, "Crystal and Magnetic Structure of Ferromagnetic Superconducting RuSr2GdCu2O8." Materials Science Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439; telephone (630) 252-5497; telefax (630) 252-9595; e-mail coble@anl.gov.
Davide Controzzi, "Superconductivity Driven by Interlayer Coupling in Strongly Correlated Electron Systems." To be published in Physica C (in press). Department of Physics, Theoretical Physics, University of Oxford, 1 Keble Road, Oxford OX1 3NP, UNITED KINGDOM; telephone +44 1865 273981; telefax +44 1865 273947; e-mail d.controzzi@physics.ox.ac.uk. Key words: strongly correlated electrons, superconductivity. 74.20.-z; 74.72.-h; 71.10.Fd.
M. Covington and L. H. Greene, "Planar Tunneling Spectroscopy of Y1- xPrxBa2Cu3O7 Thin Films as a Function of Crystallographic Orientation." Seagate Technology, Pittsburgh, PA 15203-2116; L. H. Greene's e-mail at University of Illinois at Urbana-Champaign lhg@uiuc.edu. 74.50.+r; 74.72.-h; 74.25.Fy.
G. W. Crabtree, D. Lopez, W. K. Kwok, A. M. Petrean, R. J. Olsson, H. Safar, and L. M. Paulius, "Dynamic Signatures of Driven Vortex Motion." Submitted to the Proc. of the Second Polish-U.S. Conf. on High-Temp. Supercond., Karpacz, Poland, Aug. 17-21, 1998. Contact Janice Coble, Materials Science Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439; telephone (630) 252-5497; telefax (630) 252- 9595; e-mail coble@anl.gov.
T. Dahm, D. Manske, and L. Tewordt, "Effect of a Normal-State Pseudogap on Optical Conductivity in Underdoped Cuprate Superconductors." To be published in Phys. Rev. B. Max-Planck-Institut fuer Physik Komplexer Systeme, Noethnitzer Str. 38, D-01187 Dresden, GERMANY; D. Manske's e- mail dmanske@physik.fu-berlin.de; preprint also available at http://xxx.lanl.gov/abs/cond-mat/9909219. 74.25.Gz; 74.20.Mn; 74.72.-h; 72.15.-v.
E.V.L. de Mello, "Crossover Behavior for Complex Order Parameter in High-Tc Superconductors." To be published in Physica C. Departamento de Fisica, Universidade Federal Fluminense, Av. Litoranea s/n, 24210-340 Niteroi, Rio de Janeiro, BRAZIL; e-mail evandro@if.uff.br; preprint also available at http://xxx.lanl.gov/abs/cond-mat/9909037.
J. Denul, I. Van Driessche, H. te Lintelo, R. De Gryse, A. Tsetsekou, E. Georgiopoulos, B. Glowacki, M. Vickers, R. Garre, E. Maher, J. Good, E. Ranucci, E. Larrauri, and S. Hoste, "Multi-Functional Flexible High Temperature Superconducting Tape." To be published in the Proc. of the Fourth European Conf. on Appl. Supercond. (EUCAS'99), Barcelona, Spain, Sept. 14-17, 1999. Contact I. Van Driessche, Department of Inorganic and Physical Chemistry, University of Ghent, Krijgslaan 281 (S3), B-9000 Ghent, BELGIUM; telephone +32 9 264 4440; telefax +32 9 264 4983; e-mail isabel.vandriessche@rug.ac.be.
C. C. de Souza Silva and J. Albino Aguiar, "Matching Effect and Vortex Instabilities in Nb/Al Multilayers." To be published in Physica B. Contact J. Albino Aguiar, Laboratorio de Supercondutividade, Departamento de Fisica, Universidade Federal de Pernambuco, Av. Prof. Luiz de Barros Freire s/n, 50670-901 Recife-PE, BRAZIL; telephone +55 81 271 8450; telefax +55 81 271 0359; e-mail albino@npd.ufpe.br. Key words: superconducting multilayer, vortices, matching effect, flux jumps.
Andreas Erb, "The Impact of Crystal Growth, Oxygenation and Microstructure on the Physics of the Rare Earth (123) Superconductors." Submitted as a Ph.D. thesis (Universite de Geneve). Departement de Physique de la Matiere Condensee, Universite de Geneve, 24 quai Ernest- Ansermet, CH-1211 Geneve 4, SWITZERLAND; telephone +41 22 702-6234 or -6228; telefax +41 22 702-6869; e-mail erb@sc2a.unige.ch.
H. Fang and K. Ravi-Chandar, "Fabrication of Y123 Disk by Seeded Infiltration and Growth Method." Preprint #99:075, submitted to Physica C. 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: melt-texturing, critical current density, YBCO. 74.72.-h; 74.80.Bj.
I. Grekhov, L. Delimova, I. Liniichuk, A. Lyublinsky, I. Veselovsky, A. Titkov, M. Dunaevsky, and V. Sakharov, "Growth Mode Study of Ultrathin HTSC Films on YBaCuNbO Buffer." To be published in Physica C (in press). Contact L. Delimova, Ioffe Institute, Russian Academy of Sciences, 26 Polyteknicheskaya, St. Petersburg 194021, RUSSIA; telephone +7 812 247 9311; telefax +7 812 247 9123; e-mail ladel@pop.ioffe.rssi.ru. Key words: growth mode, HTSC ultrathin film, buffer layer.
B. Guettler, S. V. Samoylenkov, and O. Yu. Gorbenko, "Raman Investigation of the Metastable Barium Cuprate BaCu3O4 in Thin Films." To be published in Physica C. Lab. 3.22, Physikalisch-Technische Bundesanstalt, Bundesallee 100, D-38116 Braunschweig, GERMANY; telephone +49 531 592 3316; telefax +49 531 592 3015; e-mail bernd.guettler@ptb.de. Key words: barium cuprate, Raman spectrometry, thin films. 78.30.-j; 74.62.Bf; 74.76.Bz.
Kikuo Harigaya, "Impurity Scattering in Metallic Carbon Nanotubes with Superconducting Pair Potentials." Physical Science Division, Electrotechnical Laboratory, Umezono 1-1-4, Tsukuba 305-8568, JAPAN; e- mail harigaya@etl.go.jp; Web site http://www.etl.go.jp/~harigaya/. 72.80.Rj; 72.15.Eb; 73.61.Wp; 73.23.Ps.
Ch. Helm, Ch. Preis, Ch. Walter, and J. Keller, "Theory for the Coupling Between Longitudinal Phonons and Intrinsic Josephson Oscillations in Layered Superconductors." Submitted to Phys. Rev. B. Division T-11, Mail Stop B-262, Los Alamos National Laboratory, Los Alamos, NM 87545; telephone (505) 667-8648; telefax (505) 665-4063; e-mail cxh@viking.lanl.gov; preprint also available at http://xxx.lanl.gov/abs/cond-mat/9909318. 74.80.Dm; 74.50.+r; 74.25.Kc; 74.25.Jb.
J. Horvat, X. L. Wang, and S. X. Dou, "Vortex Pinning in Heavily Pb- Doped Bi2212 Crystals." To be published in Physica C. Institute for Superconducting and Electronic Materials, University of Wollongong, NSW 2522, AUSTRALIA; telephone +61 2 4221 5722; telefax +61 2 4221 5731; e- mail jhorvat@uow.edu.au. Key words: flux pinning, pinning potential, heavy lead doping, Bi2212.
J. Hove and A. Sudbo, "Anomalous Scaling Dimensions and Stable Charged Fixed-Point of Type-II Superconductors." Submitted to Phys. Rev. Lett. Department of Physics, Norwegian University of Science and Technology, N-7491 Trondheim, NORWAY; telephone +47 73 59 3637; telefax +47 73 59 7710; e-mail hove@phys.ntnu.no. 74.60.-w; 74.20.De; 74.25.Dw.
Ryusuke Ikeda, "Ginzburg-Landau Approach to the Vortex-Glass Transitions due to Line-Like Disorder." Department of Physics, Kyoto University, Kyoto 606-8502, JAPAN. Key words: type-II superconductors, vortex states, vortex-glass transitions.
S. S. James, C. D. Dewhurst, R. A. Doyle, D. McK. Paul, E. Zeldov, and A. M. Campbell, "Flux Pinning, Surface and Geometrical Barriers in YNi2B2C." Submitted to the Proc. of the First Euroconf. on Vortex Matter in Superconductors, Crete, Greece, Sept. 18-24, 1999; to be published in Physica C. Interdisciplinary Research Centre in Superconductivity, University of Cambridge, Madingley Road, Cambridge CB3 0HE, UNITED KINGDOM; telephone +44 1223 337040; telefax +44 1223 337074; e-mail ssj20@cam.ac.uk. Key words: Hall probe, RNi2B2C, pinning, surface barrier, geometrical barrier.
S. S. James, S. B. Field, J. Seigel, and H. Shtrikman, "Scanning Hall Probe Microscope Images of Field Penetration into Niobium Films." Submitted to the Proc. of the First Euroconf. on Vortex Matter in Superconductors, Crete, Greece, Sept. 18-24, 1999; to be published in Physica C. Interdisciplinary Research Centre in Superconductivity, University of Cambridge, Madingley Road, Cambridge CB3 0HE, UNITED KINGDOM; telephone +44 1223 337040; telefax +44 1223 337074; e-mail ssj20@cam.ac.uk. Key words: Hall probe, superconductivity, niobium, pinning, dendrites, pattern formation, critical state.
R. Jin, Y. Liu, Z. Q. Mao, and Y. Maeno, "Selection Rule in Josephson Coupling Between In and Sr2RuO4." Submitted to Phys. Rev. Lett. Contact Y. Liu, Department of Physics, Pennsylvania State University, University Park, PA 16802; e-mail jin@phys.psu.edu; preprint also available at http://xxx.lanl.gov/abs/cond-mat/9909214. 74.50.+r; 74.25.Fy; 74.70.-b.
B. Joensson-Akerman, K. V. Rao, and E. H. Brandt, "Frequency and ac Field Scaling of the Nonlinear ac Susceptibility of a HgBa2CaCu2O6-d Thin Film." To be published in Phys. Rev. B. Department of Physics, University of California at San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0319; e-mail jjonsson@ucsd.edu. 74.60.Ge; 74.72.Gr; 74.76.Bz.
M.-H. Julien, P. Carretta, and F. Borsa, "NQR Study of Spin-Freezing in Superconducting La2-xSrxCuO4: The Example of x=0.06." Submitted to Appl. Magnetic Resonance: Proc. of the Specialized Colloque AMPERE, Pisa, Italy, June 14-18, 1999. Dipartimento di Fisica "A. Volta," Unita INFM di Pavia, Via Bassi 6, I-27100 Pavia, ITALY; telephone +39 0382 507483, ext. 465; telefax +39 0382 507563; e-mail julien@pv.infn.it or marc.henri.julien@pv.infn.it; preprint also available at http://xxx.lanl.gov/abs/cond-mat/9909351.
Ying Jer Kao, Qimiao Si, and K. Levin, "Frequency Evolution of Neutron Peaks Below Tc: Commensurate and Incommensurate Structure in LaSrCuO and YBaCuO." James Franck Institute, University of Chicago, Chicago, IL 60637; e-mail ykao@rainbow.uchicago.edu; preprint also available at http://xxx.lanl.gov/abs/cond-mat/9908302.
P. E. Kazin, V. V. Poltavets, O. N. Poltavets, A. A. Kovalevsky, Yu. D. Tretyakov, and M. Jansen, "Formation of Bi-2212 Phase and Phase Assemblage in Ga-Doped BSCCO System." To be published in Physica C (in press). Department of Chemistry, Moscow State University, 119899 Moscow, RUSSIA; telephone +7 095 939 3440; telefax +7 095 939 0998; e- mail kazin@inorg.chem.msu.ru. Key words: Bi2Sr2CaCu2O8-x, Ga doping, phase formation, microstructure.
U. Klein, D. Rainer, and H. Shimahara, "Interplay of Fulde-Ferrell- Larkin-Ovchinnikov and Vortex States in Two-Dimensional Superconductors." Institut fuer Theoretische Physik, Universitaet Linz, A-4040 Linz-Auhof, AUSTRIA; e-mail klein@gwilli.tphys.uni-linz.ac.at; preprint also available at http://xxx.lanl.gov/abs/cond-mat/9909124. 74.25.Ha; 74.80.-g; 74.80.Dm.
Hisashi Kondo and Toru Moriya, "Origin of Superconductivity in 2D- Organic Compounds and High-Tc Cuprates." To be published in J. Phys. Soc. Jpn. Department of Physics, Faculty of Science and Technology, Science University of Tokyo, Noda 278-8510, JAPAN; e-mail a6295702@rs.noda.sut.ac.jp; preprint also available at http://xxx.lanl.gov/abs/cond-mat/9909024. Key words: superconductivity, high-Tc cuprates, organic compounds, spin fluctuations, Hubbard model, pseudo-spin gap.
P. Kummeth, R. Schlosser, P. Massek, H. Schmidt, C. Albrecht, D. Breitfelder, and H.-W. Neumueller, "Development and Test of a 100 kVA Superconducting Transformer Operated at 77 K." Presented at the Fourth European Conf. on Appl. Supercond. (EUCAS'99), Barcelona, Spain, Sept. 14-17, 1999. Siemens AG, Dept. ZT EN 4, P.O. Box 3220, D-91050 Erlangen, GERMANY; telephone +49 9131 7 34254; telefax +49 9131 7 33323; e-mail peter.kummeth@erls.siemens.de.
W. K. Kwok, R. J. Olsson, G. Karapetrov, L. M. Paulius, W. G. Moulton, D. J. Hofman, and G. W. Crabtree, "Critical Points in Heavy Ion Irradiated Untwinned YBa2Cu3O7-d Crystals." Contact Janice Coble, Materials Science Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439; telephone (630) 252-5497; telefax (630) 252- 9595; e-mail coble@anl.gov. 74.60.Ge; 74.25.Dw; 74.25.Fy.
Jerome Lesueur, Xavier Grison, Marco Aprili, and Takis Kontos, "Andreev Bound States and Josephson Coupling in YBa2Cu3O7-d/Pb Tunnel Junctions." To be published in J. Low Temp. Phys.: Proc. of the Int. Conf. on Phys. and Chem. of Molecular and Oxide Supercond. (MOS'99), Stockholm, Sweden, July 28-Aug. 2, 1999. Contact Xavier Grison, C.S.N.S.M., Batiment 108, Universite Paris-Sud, F-91405 Orsay Cedex, FRANCE; telephone +33 1 6915 5231; telefax +33 1 6915 5268; e-mail grison@csnsm.in2p3.fr; preprint also available at http://xxx.lanl.gov/abs/cond-mat/9909212. 74.50.+r; 74.76.Bz; 74.72.Bk.
Q. Li, Y. N. Tsay, M. Suenaga, R. A. Klemm, G. D. Gu, and N. Koshizuka, "Bi2Sr2CaCu2O8+d Bicrystal c-Axis Twist Josephson Junctions: A New Phase-Sensitive Test of Order Parameter Symmetry." To be published in Phys. Rev. Lett. Department of Applied Science, Brookhaven National Laboratory, Upton, NY 11973. 74.50.+r; 74.80.Dm; 74.72.Hs; 74.60.Jg.
Jorge Lugo and Victor Sosa, "Levitation Force Between a Small Magnet and a Superconducting Sample of Finite Size in the Meissner State." To be published in Physica C (in press). Contact Victor Sosa, Departamento de Fisica Aplicada, CINVESTAV-IPN Unidad Merida, AP 73 Cordemex, Km. 6, Carretra Antigua a Progreso, Merida, Yucatan 97310, MEXICO; telephone +52 99 81 2973; telefax +52 99 81 2917; e-mail vic@kin.cieamer.contacyt.mx. Key words: levitation, YBCO, Meissner effect. 85.25.Ly; 74.25.Ha.
M. Majoros, B. A. Glowacki, A. M. Campbell, M. Apperley, and F. Darmann, "Transport ac Losses in (Bi,Pb)SrCaCuO-2223/Ag Multifilamentary Tapes with Different Filament Arrangements." To be published in Physica C (in press). Interdisciplinary Research Centre in Superconductivity, University of Cambridge, Madingley Road, Cambridge CB3 0HE, UNITED KINGDOM; telephone +44 1223 337441; telefax +44 1223 337074; e-mail mm293@cus.cam.ac.uk. Key words: ac losses, multifilamentary BiPbSrCaCuO tapes, filament geometry, lock-in technique.
M. Cristina Marchetti and David R. Nelson, "Vortex Physics in Confined Geometries." Submitted to Physica C. Lyman Laboratory of Physics, Harvard University, Cambridge, MA 01238; e-mail mcm@cmt.harvard.edu; preprint also available at http://xxx.lanl.gov/abs/cond-mat/9909382. Key words: vortex arrays, hydrodynamics, Bose glass, scaling. 74.60.Ge.
J. E. McCrone, J. R. Cooper, and J. L. Tallon, "Magneto-Transport Properties of the Rutheno-Cuprate RuSr2GdCu2O8." To be published in J. Low Temp. Phys.: Proc. of the Int. Conf. on Phys. and Chem. of Molecular and Oxide Supercond. (MOS'99), Stockholm, Sweden, July 28-Aug. 2, 1999. Interdisciplinary Research Centre in Superconductivity, University of Cambridge, Madingley Road, Cambridge CB3 0HE, UNITED KINGDOM; e-mail jem1007@hermes.cam.ac.uk; preprint also available at http://xxx.lanl.gov/abs/cond-mat/9909263. 74.25.Fy; 74.25.Ha; 74.72.Jt.
L. Mechin, G. J. Gerritsma, and J. Garcia Lopez, "The Direct Growth of SrTiO3 (100) Layers on Silicon (100) Substrates; Application as a Buffer Layer for the Growth of DyBa2Cu3O7-d Thin Films." To be published in Physica C (in press). GREYC (UPRESA 6072), Institut des Sciences de la Matiere et du Rayonnement, 6 Boulevard du Marechal Juin, F-14050 Caen Cedex, FRANCE; telephone +33 2 31 45 2692; telefax +33 2 31 45 2698; e- mail l.mechin@greyc.ismra.fr. Key words: silicon, YBCO, SrTiO3, buffer layer, diffusion. 74.76.-w; 73.90.+f.
J. Mesot, M. R. Norman, H. Ding, M. Randeria, J. C. Campuzano, A. Paramekanti, H. M. Fretwell, A. Kaminski, T. Takeuchi, T. Yokoya, T. Sato, T. Takahashi, T. Mochiku, and K. Kadowaki, "BSCCO Superconductors: Hole-Like Fermi Surface and Doping Dependence of the Gap Function." Contact Janice Coble, Materials Science Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439; telephone (630) 252-5497; telefax (630) 252-9595; e-mail coble@anl.gov. 74.25.Jb; 74.72.Hs; 79.60.Bm.
C. Meyers, M. Daumens, and A. Buzdin, "Surface Superconducting States near Elliptic 'Antidots' and in Elliptic Microdisks." Submitted to Physica C. Centre de Physique Theorique et de Modelisation, Universite Bordeaux I, CNRS-ERS 2120, F-33405 Talence Cedex, FRANCE; telephone +33 5 5796 2508; telefax +33 5 5796 2501; e-mail meyers@pth.u-bordeaux.fr. Key words: mesoscopic superconductors, upper critical field, surface superconductivity. 74.60.Ec; 74.80.Dm.
J. G. Naeini, J. C. Irwin, T. Sasagawa, Y. Togawa, and K. Kishio, "Temperature Dependence of the Pseudogap in La2-xSrxCuO4." Presented at the APS Centennial Meeting, Atlanta, Georgia, March 20-26, 1999; submitted to Phys. Rev. B. Contact J. C. Irwin, Department of Physics, Simon Fraser University, Burnaby, British Columbia, CANADA V5A 1S6; telephone (604) 291-3160; telefax (604) 291-3952; e-mail irwin@sfu.ca; preprint also available at http://xxx.lanl.gov/abs/cond-mat/9909342. 74.25.Gz; 74.72.Dn; 78.30.Er.
S. H. Pan, E. W. Hudson, K. M. Lang, H. Eisaki, S. Uchida, and J. C. Davis, "Imaging the Effects of Individual Zinc Impurity Atoms on Superconductivity in Bi2Sr2CaCu2O8+d." Department of Physics, University of California, Berkeley, CA 94720; e-mail ehudson@socrates.berkeley.edu; preprint also available at http://xxx.lanl.gov/abs/cond-mat/9909365.
L. M. Paulius, W.-K. Kwok, R. J. Olsson, A. M. Petrean, V. Tobos, J. A. Fendrich, G. W. Crabtree, C. A. Burns, and S. Ferguson, "Evolution of the Vortex Phase Diagram in YBa2Cu3O7-d with Random Point Disorder." Department of Physics, Western Michigan University, Kalamazoo, MI 49008. 74.25.Dw; 74.25.Fy; 74.60.Ge; 74.62.Dh.
W. E. Pickett, R. Weht, and A. B. Shick, "Superconductivity in Ferromagnetic RuSr2GdCu2O8." To be published in Phys. Rev. Lett. Department of Physics, University of California at Davis, One Shields Avenue, Davis, CA 95616-8677; telephone (530) 752-0926; telefax (530) 752-4717; e-mail pickett@solid.ucdavis.edu; preprint also available at http://xxx.lanl.gov/abs/cond-mat/9909175.
A. Pimenov, A. Loidl, B. Schey, B. Stritzker, G. Jakob, H. Adrian, A. V. Pronin, and Yu. G. Goncharov, "Universal Relationship Between the Penetration Depth and the Normal-State Conductivity in YBaCuO." To be published in Europhys. Lett. Instituet fuer Physik, Universitaet Augsburg, D-86135 Augsburg, GERMANY; e-mail andrei.pimenov@physik.uni- augsburg.de; preprint also available at http://xxx.lanl.gov/abs/cond- mat/9908383. 74.25.-q; 74.25.Fy; 74.76.Bz.
Jorge Quintanilla and Balazs L. Gyoerffy, "Finite Range Model Interaction Potential for d-Wave Superconductors: Tc vs. Doping in the Cuprates." Submitted to Physica B: Proc. of the 22nd Int. Conf. on Low Temp. Phys. (LT22), Helsinki, Finland, Aug. 5-11, 1999. H. H. Wills Physics Laboratory, University of Bristol, Royal Fort, Tyndall Avenue, Bristol BS8 1TL, UNITED KINGDOM; telefax +44 117 925 5624; e-mail j.quintanilla@bristol.ac.uk; preprint also available at http://xxx.lanl.gov/abs/cond-mat/9909052. Key words: unconventional pairing in superconductors, theories of high-temperature superconductivity.
R. Room, U. Nagel, E. Lippmaa, H. Kageyama, K. Onizuka, and Y. Ueda, "Far Infrared Study of the Two Dimensional Dimer Spin System SrCu2(BO3)2." Submitted to Phys. Rev. Lett. National Institute of Chemical Physics and Biophysics, Akadeemia tee 23, 12618 Tallinn, ESTONIA; e-mail roomtom@kbfi.ee; preprint also available at http://xxx.lanl.gov/abs/cond-mat/9909284. 78.30.Hv; 76.30.Fc; 75.30.Kz.
S. Sadewasser, J. S. Schilling, A. P. Paulikas, and B. W. Veal, "Pressure Dependence of Tc to 17 GPa With and Without Relaxation Effects in Superconducting YBa2Cu3Ox." To be published in Phys. Rev. B. Department of Physics, Washington University, C.B. 1105, One Brookings Drive, St. Louis, MO 63130
A. Sadori and M. Grilli, "Stripe Formation in Electron-Doped Cuprates." Dipartimento di Fisica, Universita di Roma 'La Sapienza' and Istituto Nazionale Fisica della Materia, P. Aldo Moro 2, I-00185 Rome, ITALY; M. Grilli's e-mail marco.grilli@roma1.infn.it; preprint also available at http://xxx.lanl.gov/abs/cond-mat/9907447. 71.10.-w; 71.28.+d; 74.72.-h; 71.45.Lr.
R. Santiago, A. Krupski, C. Boekema, and D. W. Cooke, "Maximum-Entropy muSR Analysis of Bi2212 and Tl2223 Vortex States." Submitted to the 8th Int. muSR^3 Conf. (CH'99); to be published in Physica B. Contact C. Boekema, National High Magnetic Field Laboratory, Florida State University, 1800 East Paul Dirac Drive, Tallahassee, FL 32310; e-mail boekemac@aol.com. Key words: Bi2212, Tl2223, vortex,d-wave, cuprate superconductivity.
R. R. Schulz, B. Chesca, B. Goetz, C. W. Schneider, A. Schmehl, H. Bielefeldt, H. Hilgenkamp, J. Mannhart, and C. C. Tsuei, "Design and Realization of an all d-Wave dc pi-SQUID." Experimentalphysik VI, Center for Electronic Correlations and Magnetism, Institute of Physics, University of Augsburg, Universitaetsstr. 1, D-86135 Augsburg, GERMANY; J. Mannhart's telephone +49 821 598 3650; telefax +49 821 598 3652; e- mail jochen.mannhart@physik.uni-augsburg.de.
H. Shaked, J. D. Jorgensen, O. Chmaissem, S. Ikeda, and Y. Maeno, "Neutron Diffraction Study of the Structural Distortions in Sr3Ru2O7." Contact Janice Coble, Materials Science Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439; telephone (630) 252-5497; telefax (630) 252-9595; e-mail coble@anl.gov. 61.12.-q; 64.70.Kb.
Susumu Shibata, A. K. Pradhan, and Naoki Koshizuka, "Disappearance of Peak Effect in Critical Current Density of NdBa2Cu3O7-d Single Crystals Grown Under Very Low Oxygen Partial Pressures." To be published in Jpn. J. Appl. Phys. Superconductivity Research Laboratory, International Superconductivity Technology Center (ISTEC), 10-13 Shinonome 1-chome, Koto-ku, Tokyo 135-0062, JAPAN; e-mail shibata@istec.or.jp. Key words: NdBa2Cu3O7-d, single crystal, fishtail, substitution of Nd ions, Jc, partial O2 pressure.
A. Terentiev, D. B. Watkins, L. E. De Long, D. J. Morgan, and J. B. Ketterson, "Observation of Magnetic Flux Pinning in a Thin Nb Film with a Square Lattice of Nickel Dots." To be published in Physica C (in press). Contact L. E. De Long, Department of Physics and Astronomy, University of Kentucky, CP 177, Lexington, KY 40506-0055; telefax (606) 323-2846; e-mail ldelong@pop.uky.edu. Key words: thin film superconductors, flux pinning, magnetic nanostructures, superconducting nanostructures. 74.60.Ge; 74.25.Ha; 74.76.Db; 75.70.Cn.
V. V. Tolmachev, "Superconducting Bose-Einstein Condensates of Cooper Pairs Interacting with Electrons." To be published in Phys. Lett. A. N. E. Baumann State Technical University, 2-ja Baumanscaja St. 5, 107005 Moscow, RUSSIA; e-mail tolm1930@mtu-net.ru. Key words: Cooper pairs, Bose-Einstein condensation. 74.20.-z; 74.20.Fg; 03.75.Fi.
M. I. Tsindlekht, U. Asaf, and I. Felner, "Nonlinear Properties of the Nd1.84Ce0.16CuO4 Ceramic Superconductor in a dc Magnetic Field." Submitted to Physica B: Proc. of the 22nd Int. Conf. on Low Temp. Phys. (LT22), Helsinki, Finland, Aug. 5-11, 1999. Racah Institute of Physics, Hebrew University of Jerusalem, Jerusalem 91904, ISRAEL; telephone +972 2 658 5834; telefax +972 2 658 6347; e-mail mtsindl@vms.huji.ac.il. Key words: high temperature superconductors, nonlinearity, weak links.
K. Tsutsui, T. Tohyama, and S. Maekawa, "Resonant Inelastic X-Ray Scattering in One-Dimensional Copper Oxides." Institute for Materials Research, Tohoku University, Aoba-ku, Sendai 980-8577, JAPAN; e-mail tutui@imr.tohoku.ac.jp; preprint also available at http://xxx.lanl.gov/abs/cond-mat/9909346. 78.20.Bh; 78.70.Ck; 78.66.Nk; 71.10.Fd.
I. Van Driessche, K. Coenye, F. Persyn, R. Mouton, and S. Hoste, "Improving Thermal Conductivity of Y1Ba2Cu3Oy Magnetron Sputter Targets." To be published in the Proc. of the Fourth European Conf. on Appl. Supercond. (EUCAS'99), Barcelona, Spain, Sept. 14-17, 1999. Department of Inorganic and Physical Chemistry, University of Ghent, Krijgslaan 281 (S3), B-9000 Ghent, BELGIUM; telephone +32 9 264 4440; telefax +32 9 264 4983; e-mail isabel.vandriessche@rug.ac.be.
I. Van Driessche, R. Mouton, F. Persyn, S. Hoste, E. Georgiopoulos, and A. Tsetsekou, "Development of Cylindrical Superconducting Targets by Flame and Atmospheric Plasma Spraying." To be published in the Proc. of the Fourth European Conf. on Appl. Supercond. (EUCAS'99), Barcelona, Spain, Sept. 14-17, 1999. Department of Inorganic and Physical Chemistry, University of Ghent, Krijgslaan 281 (S3), B-9000 Ghent, BELGIUM; telephone +32 9 264 4440; telefax +32 9 264 4983; e-mail isabel.vandriessche@rug.ac.be.
A. J. Zaleski and J. Klamut, "Anisotropy of the Penetration Depth in La2-xSrxCuO4 in Under- and Over-Doped Regions." To be published in J. Phys.: Cond. Matter. Institute of Low Temperature and Structure Research, Polish Academy of Sciences, P.O. Box 937, 50-950 Wroclaw, POLAND; e-mail zaleski@int.pan.wroc.pl. 74.25.Ha; 74.62.Dh; 74.72.Dn.
Andrzej J. Zaleski and Jan Klamut, "Bose-Einstein to BCS-Like Superconductor Crossover Evidence from Penetration Depth Measurements in La2-xSrxCu1-yZnyO4." To be published in Physica B. Institute of Low Temperature and Structure Research, Polish Academy of Sciences, P.O. Box 937, 50-950 Wroclaw, POLAND; e-mail zaleski@int.pan.wroc.pl. Key words: penetration depth, zinc doping, La2-xSrxCuO4, BE to BCS crossover.
Jian-Xin Zhu, "Quasiparticle Transport in c-Axis-Oriented Ferromagnet-- d-Wave Superconductor Junctions." To be published in Physica C (in press). Department of Physics and Texas Center for Superconductivity, University of Houston, Houston, TX 77204-5932; telephone (713) 743-8276; telefax (713) 743-8201; e-mail jxzhu@mira.tcs.uh.edu. Key words: d- wave superconductor, metallic, ferromagnet, Andreev reflection. 74.20.Mn; 74.80.Fp; 74.50.+r.
COMING EVENTS (An * indicates a previously listed event. Also see complete listing of upcoming conferences and workshops at our Web site http://www.iitap.iastate.edu/htcu/comevents.html.)
Feb. 10 - 11, 2000: The 2000 Wire Development Workshop of the DOE Superconductivity Program, in St. Petersburg, Fla. Recent progress in first- and second-generation wire technology will be presented by national laboratories, wire manufacturers, and other program partners. Registration information will be available at the end of November. To be added to the program's mailing list, please contact Audrey Lamanna, Energetics, telephone (202) 479-2748, e-mail alamanna@energeticsinc.com.
Feb. 13 - 18, 2000: Gordon Research Conference on Superconductivity -- Harbortown Resort, Ventura, Calif. Session titles include new materials; pseudogap and normal state properties; stripe phases; vortex physics; applications; novel heavy electron, organic, and magnetic superconductors; condensation energy; pairing symmetry, and mechanisms; theory; and c-axis transport. For further information, contact M. Brian Maple, Conference Chair, Department of Physics -- 0319, University of California at San Diego, 9500 Gilman Drive, La Jolla, CA 92093; e-mail mbmaple@ucsd.edu. Applications should be sent to Conference Application, Gordon Research Conferences, University of Rhode Island, P.O. Box 984, West Kingston, RI 02892-0984; e-mail app@grcmail.grc. uri.edu (send/request e-mail application form from this address).
April 30 - May 3, 2000: 102nd Annual Meeting & Exposition Gateway to the New Millennium, St. Louis, Mo. This is the premier inter-national forum for ceramics. Comprehensive coverage of ceramic and materials science, engineering, technology, manufacturing, and applications. The program will include symposia and focused programs: the symposia are designed to provide multidisciplinary perspectives on the nature and impact of state-of-the-art ceramic science, engineering, and technology in key areas, and the focused programming provides forums for in-depth technical exchange on specialized topics. Symposia will include ceramics and integrated components in microelectronics, optoelectronics, wireless communications and consumer electronics; ceramics for biological, chemical, mechanical, thermal and high-radiation applications; processing of ceramics; and cross-cutting symposia. Abstract deadline, November 15, 1999. For information, contact The American Ceramic Society, P.O. Box 6136, Westerville, OH 43086-6136; telephone (614) 890-4700; telefax (614) 899-6109; e-mail info@ acers.org. http://www.acers.org/.
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Scholarships for Postgraduate Students: The Institute of Superconducting and Electronic Materials (ISEM) at University of Wollongong has a number of top-up scholarships available for Australian and Overseas graduate students. These scholarships complement the Australian Postgraduate Ward ($A16,200) and Overseas Postgraduate Research Scholarship, both available at University of Wollongong. The top-up level is from $A8,000 to $A15,000, depending upon the qualification and merit, and all these scholarships are tax-free. ISEM consists of more than 40 researchers and postgraduate students and is equipped with modern facilities; its Ph.D. graduates have been accepted by a number of prestigious universities and institutions worldwide. Potential candidates for postgraduate studies are encouraged to apply for these scholarships. Application deadline, Oct. 31, 1999. Please contact Ms. Babs Allen, ISEM, University of Wollongong, Northfields Avenue, Wollongong, NSW 2522, Australia; telephone +61 4221 5730; telefax +61 4221 5731; e-mail babs_allen@uow.edu or shi_dou@uow.edu.au.
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Project Director/Editor: Sreeparna Mitra Science Editor: John R. Clem High-Tc Update, Vol. 13, #20, October 15, 1999.