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NOTA BENE:
Thin Films
The development of a high-Tc circuit technology based on Josephson devices has been impeded by the difficulty of reproducibly fabricating uniform junctions with appropriate values of the key electrical properties. A process that shows promise of overcoming this difficulty is described in preprints by B. H. Moeckly and K. Char (Conductus) and by B. H. Moeckly (Conductus) et al., in which they describe a method for fabricating YBa2Cu3O7-d (YBCO) thin-film ramp-type edge junctions with an engineered, plasma-processed interface that does not involve the deposition of a barrier.
To create the engineered interface, the authors first deposit a YBCO film and produce a ramp edge using a standard Ar ion-milling procedure. Immediately prior to surface treatment and deposition of the top YBCO counterelectrode, the base layer is given an Ar ion-mill cleaning at 500 V. The sample is then mounted in the laser deposition chamber and heated to 400-600^oC in vacuum for 30 min. Next the authors form a plasma by biasing the heater with an rf source, using Ar and/or O2 as the ionizing gas at pressures 10-100 mTorr. The plasma treatment is carried out for several minutes with a forward power of 100-400 W and a dc self bias of 200-900 V. Values of the gas pressures and rf power are selected to determine the junction parameters. Following the plasma treatment, an optional further vacuum-annealing step may be performed. The second YBCO layer is then deposited, and finally these multilayered films are patterned to form five junctions per chip with cross-sectional dimensions of 4 micrometer x 150 nm.
The resulting devices display excellent RSJ-type I-V characteristics with values of I_c and R_n tunable over a useful range for operation of digital circuits, and with spreads of I_c and R_n less than 10%. Junctions with I_c of several hundred microamperes and R_n of 2 ohms at 40 K would be ideally suited for RSFQ (rapid single flux quantum) technology. Though not presently useful for making SQUIDs at 77 K, the present method is capable of producing 1 ohm SQUIDs with an I_c of 1 mA at 40 K.
A paper by C. Weber et al. (Juelich) reports the properties of YBa2Cu3O7-d films grown on SrTiO3 that had narrowly defined regions in which Co ions were implanted. The authors found that during the YBCO deposition, Co diffused into the YBCO, forming YBa2Cu3-xCoxO7-d. However, the strong lateral diffusion of Co along the CuO2 layers remains a major obstacle to reaching the fine spatial resolution needed to form Josephson junctions with Co-doped YBCO as the barrier.
A preprint by B. M. Hinaus (Wisconsin) et al. reports the temperature (T) dependence of the normal-state resistance R_n and critical current I_c in field-emission-gun electron-beam-written YBa2Cu3O7-d Josephson junctions from the electrode's transition temperature (Tc) down to 1.5 K. From a theoretical fit to I_c(T) and R_n(T), the authors find that the Josephson barrier exhibits properties of a small Fermi-surface-area, dirty normal metal near its maximum metallic resistivity. From conventional SNS theory, the authors determine that the barrier is 3.5 mean-free paths long at Tc, with a normal-metal coherence length at Tc intermediate between the clean and dirty limits.
As pointed out by M. S. Rzchowski and B. M. Hinaus (Wisconsin), the properties of planar high-temperature superconducting Josephson junctions are not entirely consistent with low-Tc models. The authors show that some of the altered properties are extrinsic: nonuniform current feed in a planar geometry leads to a reduced critical current, an unchanged Meissner field H_[co], and a power-law dependence of the critical current on H_[co] different from that expected in an overlap geometry.
Anisotropic flux pinning and anisotropic resistivity in the substrate plane of YBCO thin films grown on vicinal, 1.2 degrees and 10 degrees miscut SrTiO3 (001) have been observed by T. Haage et al. (MPI- Stuttgart). The YBCO films grew with c-axis orientation but with parallel terraces on the surface and an array of antiphase boundaries at the step edges. The ratios of their 4.2 K critical current densities J_[cL]/J_[cT], parallel and perpendicular, respectively, to the steps (describing the pinning forces opposing motion perpendicular and parallel, respectively, to the edges) were in the range 2-5 for the 10 degrees miscut substrate and 1.5-2.5 for the 1.2 degrees miscut substrate. The value of J_[cL](4.2K) ranged up to 8 x 10^7 A/cm^2. The authors thus suggest that film growth on tailored substrates is a promising tool in scientific investigations of pinning mechanisms and in technologically driven efforts to enhance critical current densities in high-temperature superconductors.
A preprint by R. Grosser et al. (Regensburg) reports the levitation of a small permanent magnet inside a parallel-plate capacitor made of YBCO thin films. The nonlinear damping of small translational oscillations of the magnet was measured and found to be orders of magnitude lower than in bulk YBCO samples.
As reported by M. Lorenz (Leipzig) et al., Ag doping improves the quality of pulsed-laser-deposited, double-sided, three-inch-diameter YBCO and GBCO (GdBa2Cu3O7-d) thin films intended for microwave applications in satellite and telecommunication systems.
RHEED, XPS, and UPS investigations by H. Yamamoto et al. (NTT) have shown that the surface of MBE-grown Nd1.85Ce0.15CuO4 is substantially more stable than previously reported, showing only slight degradation after exposure to air for two weeks.
RBa2Cu3O7-d
A preprint by A. Erb et al. (Geneve) describes how to reversibly suppress the fishtail anomaly in pure single crystals of YBa2Cu3O7-d and NdBa2Cu3O7-d, thus changing the pinning properties of these compounds. The authors also show that for the same annealing temperature, Er-doped NdBa2Cu3O7-d has a significantly higher Tc than pure NdBa2Cu3O7-d. This occurs because the Er raises the oxygen diffusivity by an order of magnitude and dramatically reduces the time required for full oxygenation.
The microstructures and superconducting properties of melt-processed (R,R')BCO composites, where R and R' are two different rare-earth elements selected from Nd, Sm, Eu, Gd, and Y, have been studied by T. Saitoh (Iwate) et al. All the samples showed onset superconducting transition temperatures exceeding 93 K with a sharp transition, and exhibited a secondary peak effect in the M-H hysteresis loops.
The effect of additional heat treatment on the superconducting transition and the flux-pinning properties of NdBa2Cu3O7-d melt-textured in air has been studied by N. Chikumoto et al. (SRL-ISTEC). The authors found that the increase in Jc was very small, the secondary peak effect in Jc could not be observed, and the spatial variation of the Nd/Ba ratio was reduced.
The homogeneity of the superconducting properties of a large-grain (2 cm diameter) YBa2Cu3O7-d sample fabricated by SmBa2Cu3O7-d-seeded melt growth has been investigated in detail by C. D. Dewhurst et al. (IRC- Cambridge). The authors found the observed variation of the critical current density and irreversibility field with position to be associated primarily with the reduced transition temperature in the vicinity of the seed, a degradation in the microstructure towards the sample edge, and a variation in the Y2BaCuO5 inclusion density with sample radius.
The dimensionality of the superconducting state in oxygen-reduced YBa2Cu3O6.7 (Tc = 63 K) has been investigated by N. E. Hussey (IRC- Cambridge) et al. using measurements of the low-field magnetization M(H) with the field applied parallel to the CuO2 planes. At low temperatures, the authors found that the c-axis surface screening currents are strongly suppressed by vortices penetrating between the planes, indicating that the individual CuO2 planes are weakly coupled via the Josephson interaction. The results show that removal of oxygen from the chains results in a dimensional crossover of the superconducting state in YBa2Cu3O7-d.
The temperature dependence of the low-frequency part of the electronic Raman scattering in single-crystal NdBa2Cu3O7-d has been investigated by O. V. Misochko (ISSP-Chernogolovka and SRL-ISTEC) et al. using light polarized parallel and perpendicular to the CuO2 planes. The in-plane pair-breaking peaks are at 330 cm^[-1] for A_[1g]symmetry and 580 cm^[- 1] for B_[1g]. Assuming that these values correspond to the superconducting gap 2[Delta], the 2[Delta]/k_BTc ratios (5.2 and 8.5) are almost the same as in YBa2Cu3O7-d.
Bi Cuprates
Tunneling measurements are reported by N. Miyakawa (Argonne and Science University of Tokyo) et al. for break junctions in Bi2Sr2CaCu2O8+d (Bi- 2212) single crystals with various oxygen concentrations. The superconducting energy gaps observed in the underdoped samples are considerably larger (~30%) than those in optimally doped crystals. The trend of decreasing Delta_0 and 2[Delta]/k_BTc with increasing hole doping is continued into the overdoped region. The superconducting gap and strong-coupling ratio change monotonically and dramatically over a narrow doping region where Tc exhibits a maximum.
Doping effects on the superconducting gap of Bi2Sr2CaCu2O8+d for hole concentrations p in the range 0.1 <= p <= 0.21 have been studied by M. Oda et al. (Hokkaido) using scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS). The gap magnitude 2[Delta]_0 increases as p decreases below the optimal value p_o ~~ 0.17 (below which Tc starts to decrease). With decreasing p, the value of 2[Delta]_0/k_BTc rises from about 8 at p_o to about 14 at p ~~ 0.1. However, the authors note that the ratio 2[Delta]_0/k_BT*, where T* is the temperature where pseudogaps open in the electronic and magnetic energy spectra, is nearly constant for 0.1 <= p <= 0.21 with a value in the range 4-5.
Terahertz spectroscopy has been used by R. Mallozzi (UC-Berkeley and LBNL) et al. to probe both the c-axis and ab-plane conductivities in a thin film of Bi2Sr2CaCu2O8+d. The authors found a feature in the c-axis power spectrum near 300-400 GHz which the authors interpret as the zero- field c-axis plasma resonance. The dynamical conductivity in the ab plane does not fit with the picture widely used to explain the corresponding quantity in YBCO. The authors speculate that the existence of thermally generated plasma excitations in the superconducting state partially accounts for the difference in the two materials.
Systematic measurements of the low-field fluctuation magnetoconductivity in a single crystal of Bi2Sr2CaCu2O8+d are reported by R. Menegotto Costa (UFRGS-Porto Alegre) et al. Depending upon the temperature, the authors observe Gaussian, critical, and lowest-Landau-level scalings.
A paper by G. Grasso et al. (Geneve) reports an investigation of Ag- sheathed monofilamentary Bi-2223 tapes with 77 K critical current densities in the range 7-34 x 10^3 A/cm^2 in which the authors chemically etched off the silver sheath and then measured the normal- state resistivity of the bare filament. A strong correlation was found between the critical current density Jc and the normal-state resistivity rho, their product being constant regardless of the sample quality. The authors stress that this observation is in quantitative agreement with the railway-switch and parallel-pipe models, which have been proposed to explain the current-transport mechanism in Bi-2223 tapes.
A report on recent advances in processing of Ag-clad multifilamentary Bi-2223 superconducting tapes has been prepared by U. Balachandran (Argonne) et al. The 77 K, zero-field critical currents of the tapes has reached 60 A in short samples (4 cm), 54 A at a length of 164 m, and 18 A over a length of 1,260 m. The maximum critical current values were two to three times higher in slow-cooled tapes than in fast-cooled tapes. Related development work is reported in two preprints by N. Vasanthamohan et al. (Argonne).
Other Cuprates
A strong superconductivity-induced phonon renormalization effect has been observed by V. G. Hadjiev (MPI-Stuttgart) et al. in the HgBa2Ca3Cu4O10+d (Hg-1234) superconductor (Tc = 123 K). The authors found that the A_[1g] phonons at 240 cm^[-1] and 390 cm^[-1], which correspond to vibrations of the plane oxygen atoms with some admixture of calcium vibrations, display an abrupt softening and increase in linewidth within a narrow temperature interval at the transition from the normal to the superconducting state. The changes of phonon self- energy are accompanied by a strong enhancement of the Raman intensity of the phonons in the superconducting state. The authors stress that these phonon self-energy effects are the strongest ones so far reported for the superconducting cuprates.
A preprint by S. Dorbolo et al. (Liege) reports a theoretical analysis of the specific heats of single-crystal YBa2Cu3O7-d and HgBa2Ca2Cu3O8+d (Hg-1223) in a magnetic field. The authors take into account critical XY and Gaussian fluctuation regimes.
The anisotropic resistivity of high-quality single crystals of YBa2Cu4O8 has been measured by N. E. Hussey (Tokyo) et al. along all three crystallographic axes up to 450 K. In contrast to other underdoped cuprates, the c-axis resistivity shows a striking crossover from incoherent to metallic behavior with decreasing temperature. The authors note that since YBa2Cu4O8 is naturally stoichiometric with negligible disorder between the CuO2 planes, its c-axis response may reflect the intrinsic behavior of the out-of-plane conductivity in underdoped cuprates; this behavior thus represents an important challenge to the generally accepted picture of charge confinement in these systems.
Vortices
Local magnetic measurements by D. Giller (Bar-Ilan) et al. in a highly anisotropic Nd-Ce-Cu-O crystal reveal a sharp onset of an anomalous magnetization peak at a temperature-dependent field B_[on]. The same field marks a change in the field profiles across the sample, from profiles dominated by geometrical barriers below B_[on] to Bean-like profiles above it. The temperature dependence of B_[on] and the flux distribution above and below B_[on] imply a disorder-induced transition at B_[on] from a relatively ordered vortex lattice to a highly disordered, entangled vortex solid. Local magnetic relaxation measurements above B_[on] show evidence for plastic vortex creep associated with the motion of dislocations in the entangled vortex structure.
A preprint by K. E. Gray (Argonne) reports measurements of the flux-flow voltage noise in epitaxial YBa2Cu3O7-d films and presents an analysis that yields vortex correlation lengths and bundle sizes. The author finds that at high temperatures, the bundle size grows with the c-axis correlation length of pancake vortices, while at low temperatures, flux creep is consistent with vortex-line bundles that are larger than a minimum size. The separation of the two regimes is roughly at the vortex-lattice melting line, implying that a large c-axis correlation length is needed for vortex-lattice freezing.
Using a 2DEG (two-dimensional electron gas) micro Hall probe, T. Tsuboi et al. (Tokyo) et al. have measured the local magnetic-field noise generated by current-driven vortices near the vortex-lattice melting field H_m in Bi2Sr2CaCu2O8+d (Bi-2212). Broad-band noise (BBN) was found to occur just when the pinned vortices start moving under the Lorentz force. When the vortex velocity increased, the BBN disappeared, but narrow-band noise (NBN) then developed. The two types of noise occurred in both the solid and liquid vortex phases.
Small-angle neutron-diffraction experiments probing the vortex lattice in YBCO have been analyzed by D. Chang (National Tsing Hua) et al., using a one-field free-energy method. The authors find for the experiments of B. Keimer et al. [Phys. Rev. Lett. 73, 3459 (1994)] that the fourfold symmetry of the underlying crystal is broken, but reflection symmetry with respect to the [110] and [110] axes is preserved. The vortex lattice also becomes oblique instead of rectangular body-centered.
As shown by J. E. Sonier (TRIUMF and UBC) et al., the internal-field distribution in the vortex state of YBa2Cu3O6.60 is a sensitive measure of both the magnetic penetration depth lambda_[ab] and the vortex-core radius rho_0. The authors report that the temperature dependence of rho_0 is weaker than in the conventional superconductor NbSe2 and much weaker than theoretical predictions for an isolated vortex. The effective vortex-core radius decreases sharply with increasing H, while the field dependence of lambda_[ab](H) is much stronger than in NbSe2.
A preprint by S. S. Banerjee (TIFR) et al. reports that CeRu2 and 2H- NbSe2 display remarkable similarities in their magnetic response, reflecting the manner in which the weakly pinned flux-line lattice (FLL) loses spatial order in the peak-effect regime. The authors attribute the observed discontinuous change in screening response near the peak- effect onset, and the history dependence in it, to a disorder-induced fracturing of the FLL, as an alternative to the scenario involving the appearance of spatial modulation in the superconducting order parameter of CeRu2.
Two papers by M. Chandran (Indore) report the development and application of a method for computing the critical-state penetration of magnetic flux into thin superconductors. The method involves dividing up the superconductor into a two-dimensional Josephson-junction array. The author accounts for the nonlocal interaction of fields and currents by including the mutual inductance between all pairs of plaquettes in the array. Hysteretic M-H magnetization loops and the field distribution within the array are calculated for both field-independent and field-dependent Josephson critical current densities. The author also calculates two-dimensional magnetic-field profiles for flux penetration into square and rectangular samples with and without holes.
Theory
A detailed study of the nonequilibrium steady states of a periodic medium driven over a random or periodic substrate is given in a preprint by L. Balents (UC-Santa Barbara) et al. For those in the superconductivity community, the relevant application is the transport- current-driven motion of a vortex lattice over an array of pinning centers. Starting with a microscopic lattice Hamiltonian, the authors use a coarse-graining procedure to derive continuum hydrodynamic equations of motion in the laboratory frame. They then investigate numerous consequences of the resulting equations.
As noted by W. C. Wu and J. P. Carbotte (McMaster), for an unconventional superconductor with nodes in the gap, it is known that the in-plane microwave or dc conductivity saturates at low temperatures to a universal value independent of the impurity concentration. The authors demonstrate that a similar feature can be accessed using channel-dependent Raman scattering. For a d_[x^2-y^2]-wave superconductor, they find that the slope of the low-temperature Raman intensity at zero frequency is universal in the A_[1g] and B_[2g] channels, but not in the B_[1g] channel. Moreover, as opposed to the microwave conductivity, universal Raman slopes are sensitive not only to the existence of a node, but also to different pairing states; this should allow one to distinguish between such pairing states.
The maximum at 41 meV in the inelastic spin-flip neutron scattering from YBa2Cu3O7-d is explained by A. A. Abrikosov (Argonne) in terms of the author's extended saddle-point model. The author finds that for a maximum to appear in the imaginary part of the spin susceptibility, the Fermi energy must lie close to the extended saddle point. The energy of the maximum is then close to 2[Delta]_[max], in agreement with experiment.
A paper by R. M. Quick (Pretoria) and S. G. Sharapov (Kiev) describes a theoretical model in which a pseudogap phase persists even when coherent interlayer tunneling is taken into account.
A variational treatment of the ground state of the two-leg t-J ladder is presented in a preprint by G. Sierra (UC-Santa Barbara) et al. This treatment combines the dimer and the hard-core boson models into one effective model and permits a study of the local structure of the hole pairs as a function of doping. The authors find that the local structure of the pairs depends upon whether the ladder is slightly or strongly doped.
A microscopic model of electron interactions that gives rise to both superconductivity and antiferromagnetism and admits an approximate SO(5) symmetry relating these two phases has been constructed by C. P. Burgess (McGill) et al. The symmetry can be exact, or it may exist only in the long-wavelength limit, depending on the detailed form of the interactions. By explicitly integrating out the fermions, the authors compute the macroscopic Landau-Ginzburg free energy for this model as a function of temperature and doping. The resulting phase diagram can resemble that observed for the cuprates, with the antiferromagnetism realized as a spin-density wave, whose wavelength might be incommensurate with the lattice spacing away from half-filling.
As stressed in a preprint by A. Bill (LBNL) et al., the ordering trend of magnetic impurities at low temperatures results in frustration of the pair-breaking effect and induces a recovery of superconducting properties. The authors show that this effect manifests itself in a deviation of the Josephson-current amplitude from the values obtained within the Ambegaokar-Baratoff and Abrikosov-Gor'kov models. The authors apply the theory to describe experimental data for the low-Tc superconductor SmRh4B4, and they predict a recovery effect of the Josephson current in high-temperature superconductors.
Applications
A preprint by E. Dantsker (UC-Berkeley and LBNL) et al. describes a planar HTS gradiometer that consists of a directly coupled SQUID magnetometer inductively coupled to a single-layer YBCO flux transformer. The device was balanced to about one part in 3,000 with respect to fields perpendicular to its plane, and it had a baseline of 48 mm. This approach to gradiometers offers advantages of simplicity and low cost while combining the requirements of a high degree of balance and a long baseline.
The stability over time of high-Tc SQUIDs with ramp-edge Josephson junctions (Ag:YBa2Cu3O7-d/PrBa2Cu3O7-d/Ag:YBa2Cu3O7-d) is reported in a paper by Q. X. Jia (Los Alamos) et al. The critical current of the devices tended to decrease with a mean percentage of less than 7% over a period of more than 500 days, while the junction resistance increased with a mean percentage of 5%. The voltage modulation of the SQUIDs, however, was unchanged within experimental reproducibility, evidently because of the cancellation of the changes in critical current and resistance.
High-Tc GdBa2Cu3O7-d superconducting transition-edge bolometers with operating temperatures near 89 K, large receiving areas of 0.95 mm^2, and high detectivity in the far infrared have been made by M.J.M.E. de Nivelle (Utrecht) et al. The bolometers are supported by silicon nitride membranes of thickness 0.62 micrometer and have a gold black absorption coating. The authors have measured and theoretically analyzed the noise characteristics, taking into account the influence of electrothermal feedback on the noise. The responsivity was measured for wavelengths in the range 70-200 micrometers. The lowest measured noise equivalent power (NEP) was 5.5 pW/Hz^[1/2], which corresponds to a record detectivity of 1.8 x 10^[10] cm Hz^[1/2]/W. The authors also report that no degradation of the bolometers could be observed after vibration tests, thermal cycling, and half a year storage.
Progress in the performance of melt-cast-processed Bi-2212 conductors with integrated silver contacts is reported by P. F. Herrmann (Alcatel Alsthom) et al. Tubes of diameter 0.3 m and length up to 0.5 m can be fabricated. For tubes of diameter 70 mm, the critical current at 77 K is in the 10 kA range, and the current density approaches Jc = 10^3 A/cm^2. This current-carrying capacity in combination with a very low thermal conductivity allows these conductors to be used as high- performance current leads for low-temperature applications. The authors also discuss the use of these materials for field windings, power transformers, and fault-current limiters.
The magnetic levitation forces of melt-textured YBCO monoliths intended for use in permanent magnet-superconductor arrangements for magnetic bearings of a liquid hydrogen tank are reported by M. Ullrich (Goettingen) et al. The authors found that the difference in the critical current density between large-grained and single-domain samples decreases strongly with decreasing temperature.
Other Activities
A preprint by M. Chandran (Indore) presents results of a Langevin dynamics simulation of an inductively coupled Josephson-junction array in the absence of pi junctions. The author finds that the magnetic susceptibility under field-cooled conditions becomes positive in a certain range of applied fields, while the zero-field-cooled susceptibility is negative for all applied fields. The author relates these findings to recent experiments which have shown a paramagnetic Meissner effect (PME) in some samples.
Overviews
An introductory review of classical and high-temperature superconductivity, intended mainly for nonspecialists, has been prepared by J. H. Miller, Jr. and J. R. Claycomb (TCSUH). After providing a historic overview, the article focuses on the macroscopic electrodynamic properties of both classical and cuprate superconductors. Next, certain aspects of the microscopic pairing theory of superconductivity, originally proposed by Bardeen, Cooper, and Schrieffer, are briefly summarized, followed by a discussion of Josephson junctions. The structural and electronic properties unique to cuprate superconductors, as well as their superconducting pairing-state symmetry and proposed pairing mechanisms, are then described. Recent progress in the development of applications is then briefly covered. Finally, the article concludes with a discussion of possible future directions (136 refs.).
An article by R. S. Prasher and P. E. Phelan (Arizona State) compiles all the theoretical and experimental work to date on the thermal boundary resistance R_b between high-Tc superconductors and other solids, both in thin-film and bulk forms, and provides a critical review of the cited works (43 refs.).
A book chapter by Y. De Wilde (Argonne) et al. describes the vortex- lattice structure in LuNi2B2C. Scanning tunneling microscope studies at 4.2 K have revealed that the vortex lattice is square in high external fields along the [001] direction. According to the authors, it is likely that in LuNi2B2C and similar borocarbide compounds nonlocal effects are at the origin of an additional four-fold-symmetry-breaking term which stabilizes a square vortex lattice at high fields (40 refs.).
Theses
The microstructural features of melt-processed YBa2Cu3O7-d and GdBa2Cu3O7-d were studied in the Hyderabad Ph.D. thesis of E. S. Reddy. The author also developed a process for the fabrication of near-net- shaped, melt-textured YBCO and GBCO superconductors, and investigated the advantages and limitations of this process (285 refs.).
The superconducting phase diagram of YBa2(Cu1-xFex)3Oy, 0 <= x <= 1/3, has been investigated in the Cincinnati M.S. thesis of F. Shi for bulk samples prepared at ambient and high oxygen pressures. The author reports that samples with x in the range 0.15 <= x <= 1/3 can be transformed from antiferromagnetic insulators or semiconductors to superconductors with Tc in the range 52-60 K by annealing at 915^oC under an oxygen pressure of 27 MPa (65 refs.).
Contributed by John R. Clem
Contents: Preprints begin on page 6; Coming Events begin on page 13; Resources are on page 14; FYI is on page 14; and Donors begin on page 14.
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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.
A. A. Abrikosov, "The Neutron Peak in the Extended Saddle Point Model of High Temperature Superconductors." 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.
A. R. Anderson, P. A. Miles, Genda Gu, G. J. Russell, S. J. Kennedy, and N. Koshizuka, "A Proposal for a Structural Change in Bi(2212) at 167 K." To be published in Physica C (in press). Advanced Electronic Materials Group, School of Physics, University of New South Wales, Kensington NSW, AUSTRALIA.
M.A.N. Araujo, M. Dzierzawa, C. Aebischer, and D. Baeriswyl, "Cooper Pair Delocalization in Disordered Media." Departamento de Fisica da Universidade de Evora, 7000 Evora, PORTUGAL; M. Dzierzawa's e-mail at Universitaet Augsburg, GERMANY, michael.dzierzawa@physik.uni- augsburg.de; preprint also available at cond-mat@xxx.lanl.gov (#9708021).
U. Balachandran, M. Lelovic, T. Deis, N. G. Eror, P. Haldar, and V. Selvamanickam, "Recent Advances in Processing of Ag-Clad Bi-2223 Superconductors." To be published in the Proc. of the Int. Cryogenic Eng. Conf. and the Int. Cryogenic Mater. Conf. (1997 Joint ICMC-CEC Conf.), Portland, Oreg., July 27-Aug. 1, 1997. Contact Janice Coble, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439; telefax (708) 252-9595; e-mail janice_coble@qmgate.anl.gov.
Leon Balents, M. Cristina Marchetti, and Leo Radzihovsky, "Nonequilibrium Steady States of Driven Periodic Media." Institute for Theoretical Physics, University of California, Santa Barbara, CA 93106- 4030. 64.60.Fr; 74.20.De.
S. S. Banerjee, N. G. Patil, Subir Saha, S. Ramakrishnan, A. K. Grover, S. Bhattacharya, G. Ravikumar, P. K. Mishra, T. V. Chandrasekhar Rao, V. C. Sahni, M. J. Higgins, E. Yamamoto, Y. Haga, M. Hedo, Y. Inada, and Y. Onuki, "Anomalous Peak Effect in CeRu2 and NbSe2: Fracturing of a Flux Line Lattice?" Preprint #TIFR/CM/97/105(I); submitted to Phys. Rev. Lett. Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400 005, INDIA; telephone +91 22 215-2971 or -2979; telefax +91 22 215- 2110 or -2181; e-mail satya@tifrc2.tifr.res.in. Key words: flux line lattice, type II superconductors, peak effect, history dependence, fracturing, phase diagram. 64.70.Dv; 74.60.Ge; 74.25.Dw; 74.60.Ec; 74.60.Jg.
A. Bill, S. A. Wolf, Yu. N. Ovchinnikov, and V. Z. Kresin, "Effect of Magnetic Impurity Correlations on Josephson Tunneling." Lawrence Berkeley Laboratory, University of California, MS 62-203, 1 Cyclotron Road, Berkeley, CA 94720; telephone (510) 486-6991; telefax (510) 486- 5401; e-mail abill@lbl.gov. Key words: Josephson effect, pair breaking. 74.50.+r; 74.62.Dh.
M.-C. Bunescu, G. Aldica, P. Badica, F. Vasiliu, P. Nita, and S. Mandache, "SEM Studies on BSCCO Superconducting Ceramic Produced by Spray Frozen, Freeze Drying Technique." To be published in Physica C (in press). METAV-S.A., P. O. Box 18/3, Bucharest, ROMANIA; telephone +40 1 2323068; telefax +40 1 2323076. Key words: SEM, EDS, crystal morphology, ac susceptibility superconducting ceramic, BSCCO, spray- frozen freeze-drying technique.
C. P. Burgess, J. M. Cline, R. MacKenzie, and R. Ray, "A Microscopic Derivation of the SO(5)-Symmetric Landau-Ginzburg Potential." Department of Physics, McGill University, 3600 University Street, Montreal, Quebec, CANADA H3A 2T8; J. M. Cline's e-mail jcline@hep.physics.mcgill.ca; preprint also available at cond- mat@xxx.lanl.gov (#9707290).
Mahesh Chandran, "Critical State in Thin Superconductors: A Josephson Junction Array Analogy." To be published in Physica C. Low Temperature Physics Group, Center for Advanced Technology, P.O. CAT, Indore 452013, INDIA; telefax +91 731 488300; e-mail maheshc@cat.ernet.in. 74.60.-w; 74.76.-w; 74.50.+r.
Mahesh Chandran, "Field Distribution in Thin Superconductors: Effect of Sample Shape." To be published in Physica C. Low Temperature Physics Group, Center for Advanced Technology, P.O. CAT, Indore 452013, INDIA; telefax +91 731 488300; e-mail maheshc@cat.ernet.in. 74.25.Nf; 74.60.Ge; 74.80.Dm.
Mahesh Chandran, "Positive Moment of an Inductively Coupled Josephson Junction Array." To be published in Phys. Rev. B. Low Temperature Physics Group, Center for Advanced Technology, P.O. CAT, Indore 452013, INDIA; telefax +91 731 488300; e-mail maheshc@cat.ernet.in. 74.60.-w.
D. Chang, C.-Y. Mou, B. Rosenstein, and C. L. Wu, "An Interpretation of the Neutron Scattering Data on Flux Lattices of Superconductors." Submitted to Phys. Rev. Lett. Contact C. L. Wu, Department of Physics, National Tsing Hua University, Hsinchu 30043, Taiwan, REPUBLIC OF CHINA; e-mail d833323@phys.nthu.edu.tw; preprint also available at cond- mat@xxx.lanl.gov (#9708079). 74.20.De; 74.25.Fy; 74.60.-w.
N. Chikumoto, J. Yoshioka, and M. Murakami, "Improved Superconducting Properties of Melt-Textured Nd123 by Additional Heat Treatment." To be published in Physica C. Superconductivity Research Laboratory, International Superconductivity Technology Center (ISTEC), 16-25 Shibaura 1-chome, Minato-ku, Tokyo 105, JAPAN. Key words: Nd-Ba-Cu-O, melt process, heat treatment, critical current density, critical temperature.
R. Menegotto Costa, P. Pureur, L. Ghivelder, J. A. Campa, and I. Rasines, "Gaussian, 3D-XY and LLL Scalings in the Low-Field Fluctuation Magnetoconductivity of Bi2Sr2CaCu2O8." To be published in Phys. Rev. B. Contact P. Pureur, Instituto de Fisica, Universidade Federal do Rio Grande do Sul, P.O. Box 15051, 91501-970 Porto Alegre, BRAZIL; telephone +55 51 316 6458; telefax +55 51 319 1762; e-mail ppureur@if.ufrgs.br. Key words: magnetoresistance, fluctuation effects, critical phenomena. 74.72.Hs; 74.25.Fy; 74.40.+k.
Eugene Dantsker, O. Froehlich, S. Tanaka, K. Kouznetsov, John Clarke, Z. Lu, V. Matijasevic, and K. Char, "High-Tc Superconducting Gradiometer with a Long Baseline Asymmetric Flux Transformer." To be published in Appl. Phys. Lett. Department of Physics, University of California, Berkeley, CA 94720; e-mail gene.dantsker@trw.com. 74.76.Bz; 85.25.Dq.
M.J.M.E. de Nivelle, M. P. Bruijn, R. de Vries, J. J. Wijnbergen, P.A.J. de Korte, S. Sanchez, M. Elwenspoek, T. Heidenblut, B. Schwierzi, W. Michalke, and E. Steinbeiss, "Low Noise High-Tc Superconducting Bolometers on Silicon Nitride Membranes for Far-Infrared Detection." To be published in J. Appl. Phys. Space Research Organization Netherlands, Sorbonnelaan 2, 3584 CA Utrecht, THE NETHERLANDS; telephone +31 30 253 5600; telefax +31 30 254 0860; e-mail m.denivelle@sron.ruu.nl.
C. D. Dewhurst, Wai Lo, Y. H. Shi, and D. A. Cardwell, "Homogeneity of Superconducting Properties in SmBa2Cu3O7-d Seeded Melt Processed YBCO." Interdisciplinary Research Centre in Superconductivity, University of Cambridge, West Cambridge Site, Madingley Road, Cambridge CB3 0HE, UNITED KINGDOM; telephone +44 1223 337441; telefax +44 1223 337074; e- mail cdd1001@cus.cam.ac.uk; preprint also available at Web site http://www.sucon.cam.ac.uk/staff/Charles_Dewhurst/cdd-home.htm.
Y. De Wilde, M. Iavarone, V. I. Metlushko, U. Welp, A. K. Koshelev, I. Aranson, G. W. Crabtree, and P. C. Canfield, "Vortex Lattice Structure in LuNi2B2C." To be published in Superconductors in a Magnetic Field, edited by C. Sa De Melo (World Scientific). Contact Janice Coble, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439; telefax (708) 252-9595; e-mail janice_coble@qmgate.anl.gov.
S. Dorbolo, M. Houssa, and M. Ausloos, "Contributions of Critical and Gaussian Fluctuations to the Specific Heat in YBa2Cu3O7-x and in HgBa2Ca2Cu3O8 Under a Magnetic Field." Submitted to Supercond. Sci. & Technol. SUPRAS, Institute of Physics B5, University of Liege, B-4000 Liege, BELGIUM. 74.25.Bt; 74.60.Ec; 74.72.-h.
M. Doudkowsky, J. Santiso, S. Berton, A. Figueras, and J. Bassas, "Barium Incorporation in c-axis Oriented YBCO Thin Films Deposited by Metalorganic Chemical Vapor Deposition." To be published in Physica C (in press). Contact J. Santiso, Institut de Ciencia de Materials de Barcelona (CSIC), Campus de la Universitat Autonoma de Barcelona, 08193 Bellaterra, Barcelona, SPAIN; e-mail santiso@icmvax.icmab.es. Key words: YBCO, thin films, MOCVD, off-stoichiometric composition, Ba incorporation.
Andreas Erb, Jean-Yves Genoud, Marc Dhalle, Frank Marti, Eric Walker, and Rene Fluekiger, "On the Origin of the So-Called Fishtail Effect in Single Crystals of the RE-123 Compounds (RE = Y, Er, Nd)." To be published in the Proc. of the 3rd European Conf. on Appl. Supercond. (EUCAS'97), Veldhoven, The Netherlands, June 30-July 3, 1997. 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.
Mikhail V. Fistul and Gabriele F. Giuliani, "Effect of Randomly Distributed Anisotropic Vortices on the Critical Current of a Layered Superconductor." To be published in Physica C (in press). Department of Physics, Purdue University, 1396 Physics Building, West Lafayette, IN 47907-1396; telephone (317) 494-5384; telefax (317) 494-0706; e-mail gfg@physics.purdue.edu. Key words: Josephson junction, layered structure, vortex.
S. Fujihara, N. Yoshida, and T. Kimura, "An Orthorhombic NdBa1.5Sr0.5Cu3O7-d Superconductor Prepared Using a Ba1.5Sr0.5Cu3O5+x Precursor." To be published in Physica C (in press). Department of Applied Chemistry, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223, JAPAN; telephone +81 45 563 1141; telefax +81 45 562 7625; e-mail shinobu@applc.keio.ac.jp. Key words: NdBa2Cu3O7-d,NdBa1.5Sr0.5Cu3O7-d, substitution.
D. Giller, A. Shaulov, R. Prozorov, Y. Abulafia, Y. Wolfus, L. Burlachkov, Y. Yeshurun, E. Zeldov, V. M. Vinokur, J. L. Peng, and R. L. Greene, "Disorder-Induced Transition to Entangled Vortex-Solid in Nd-Ce- Cu-O Crystal." To be published in Phys. Rev. Lett. Department of Physics, Center for Superconductivity, Bar-Ilan University, Ramat Gan 52900, ISRAEL; Y. Yeshurun's telephone +972 3 531-8433 or -8434; telefax +972 3 535-3298.
G. Grasso, F. Marti, Y. Huang, A. Perin, and R. Fluekiger, "Correlation Between the Normal State Resistivity and the Critical Current Density of Ag Sheathed Bi(2223) Tapes." To be published in Physica C (in press). Departement de Physique de la Matiere Condensee and Groupe de Physique Appliquee, Universite de Geneve, 24 quai Ernest-Ansermet, CH-1211 Geneve 4, SWITZERLAND; telephone +41 22 702 6512; telefax +41 22 702 6869; e- mail grasso@physics.unige.ch.
K. E. Gray, "Vortex Correlation Lengths and Bundle Sizes from Voltage Noise in YBa2Cu3O7." Submitted to Phys. Rev. B. Contact Janice Coble, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439; telefax (708) 252-9595; e-mail janice_coble@qmgate.anl.gov. 74.40.+k; 74.60.Ge; 74.50.+r.
R. Grosser, A. Martin, O. Kus, E. V. Pechen, and W. Schoepe, "Levitation of a Small Permanent Magnet Between Superconducting YBa2Cu3O7-d Thin Films." Presented at the 3rd European Conf. on Appl. Supercond. (EUCAS'97), Veldhoven, The Netherlands, June 30-July 3, 1997. Institut fuer Experimentelle und Angewandte Physik, Universitaet Regensburg, D- 93040 Regensburg, GERMANY; e-mail reiner.grosser@physik.uni- regensburg.de.
T. Haage, J. Zegenhagen, J. Q. Li, H.-U. Habermeier, M. Cardona, Ch. Jooss, R. Warthmann, A. Forkl, and H. Kronmueller, "Transport Properties and Flux Pinning by Self-Organization in YBa2Cu3O7-d Films on Vicinal SrTiO3 (001)." To be published in Phys. Rev. B (Oct. 1997). Contact H.-U. Habermeier, Max-Planck-Institut fuer Festkoerperforschung, Heisenbergstrasse 1, D-70569 Stuttgart, GERMANY; telephone +49 711 689 1372; telefax +49 711 689 1389; e-mail huh@servix.mpi-stuttgart.mpg.de. 74.60.Ec; 68.55.Jk; 74.60.Jg.
V. G. Hadjiev, Xingjiang Zhou, T. Strohm, M. Cardona, Q. M. Lin, and C. W. Chu, "Strong Superconductivity-Induced Phonon Self-Energy Effects in HgBa2Ca3Cu4O10+d." Max-Planck-Institut fuer Festkoerperforschung, Heisenbergstrasse 1, D-70569 Stuttgart, GERMANY. 74.25.Gz; 71.20.Tx.
P. F. Herrmann, E. Beghin, J. Bock, C. Cottevieille, A. Leriche, and T. Verhaege, "Investigation of Melt Cast Processed Bi-2212 Conductors and Their Potential for Power Applications." Presented at the 3rd European Conf. on Appl. Supercond. (EUCAS'97), Veldhoven, The Netherlands, June 30-July 3, 1997. Alcatel Alsthom Recherche, Department of Electrotrechnique, F-91460 Marcoussis, FRANCE; telephone +33 1 69 63 1000; telefax +33 1 69 63 1600.
B. M. Hinaus, M. S. Rzchowski, B. A. Davidson, J. E. Nordman, K. Siangchaew, and M. Libera, "Nature of the Josephson Barrier in Electron- Beam Written YBa2Cu3O7-d Junctions." Department of Physics, University of Wisconsin-Madision, Madison, WI 53706. 74.50.+r; 74.80.Fp; 74.76.Bz.
N. E. Hussey, J. R. Cooper, CHEN Changkang, and J. W. Hodby, "Dimensional Crossover in the Superconducting State of Oxygen-Deficient YBa2Cu3O6.7." To be published in Physica C. Institute for Solid State Physics, University of Tokyo, 7-22-1 Roppongi, Minato-ku, Tokyo 106, JAPAN; telephone +81 3 3478 6811, ext. 5663; telefax +81 3 3478 7698; e- mail nehussey@troy.issp.u-tokyo.ac.jp. Key words: magnetization, Josephson effect, coherence length. 74.50.+r; 74.60.Ec; 74.72.Bk.
N. E. Hussey, K. Nozawa, H. Takagi, S. Adachi, and K. Tanabe, "Anisotropic Resistivity of YBa2Cu4O8: Incoherent to Metallic Crossover in the Out-of-Plane Transport." To be published in Phys. Rev. B. Institute for Solid State Physics, University of Tokyo, 7-22-1 Roppongi, Minato-ku, Tokyo 106, JAPAN; telephone +81 3 3478 6811, ext. 5663; telefax +81 3 3478 7698; e-mail nehussey@troy.issp.u-tokyo.ac.jp. 74.25.Fy; 74.72.Bk.
Q. X. Jia, D. Reagor, C. Mombourquette, Y. Fan, J. Decker, and P. D'Alessandris, "Stability of dc Superconducting Quantum Interference Devices Fabricated Using Ramp-Edge Superconductor/Normal- Metal/Superconductor Technology." Preprint #LAUR-97-3159; to be published in Appl. Phys. Lett. Materials Science and Technology Division, MS K763, Los Alamos National Laboratory, Los Alamos, NM 87545; telephone (505) 667-2716; telefax (505) 665-3164; e-mail qxjia@lanl.gov.
M. Z. Jin, X. W. Liu, M. L. Liu, J. Xu, R. Liu, and Y. Q. Jia, "Mossbauer Spectra of [57]^Fe in a Thick Film of YBa2(Cu0.97Fe0.03)3O7-x Irradiated by a Large Dose of gamma-Rays." To be published in Physica C (in press). Contact Y. Q. Jia, Department of Chemistry, East China University of Science and Technology, Shanghai 200237, PEOPLE'S REPUBLIC OF CHINA.
Tae Song Kwon, "The Role of the Copper 3d_[3z^2-r^2] Orbitals and the Charge Fluctuation Mechanism in the Hole-Doped Cuprate Superconductors." To be published in Physica C (in press). Department of Physics and Institute for Mathematical Sciences, Yonsei University, Seoul 120-749, SOUTH KOREA; telephone +82 2 361 2611; telefax +82 2 392 1592; e-mail tskwon@phya.yonsei.ac.kr. 74.20.Mn; 74.25.Jb; 74.25.Gz.
Th. Lang, D. Buhl, S. Al-Wakeel, D. Schneider, and L. J. Gauckler, "Phase Assemblage and Morphology During the Partial Melt Processing of Bi-2212 Thick Films." To be published in Physica C (in press). ETH Zurich, Department of Materials, Chair of Nonmetallic Materials, Swiss Federal Institute of Technology, Sonneggstrasse 5, CH-8092 Zurich, SWITZERLAND; telephone +41 1 632 5651; telefax +41 1 632 1132; e-mail lang@nonmet.mat.ethz.ch.
M. Lorenz, H. Hochmuth, J. Frey, H. Boerner, J. Lenzner, G. Lippold, T. Kaiser, M. A. Hein, and G. Mueller, "Ag-Doped Large-Area Double-Sided YBaCuO and GdBaCuO Thin Films for Microwave Applications." To be published in the Proc. of the 3rd European Conf. on Appl. Supercond. (EUCAS'97), Veldhoven, The Netherlands, June 30-July 3, 1997. Fakultaet fuer Physik und Geowissenschaften, Universitaet Leipzig, Linnestr. 5, D-04103 Leipzig, GERMANY; e-mail mlorenz@server1.rz.uni-leipzig.de.
V. S. Lysenko, Y. V. Gomeniuk, I. P. Tyagulski, I. N. Osiyuk, V. Z. Lozovski, and V. N. Varyukhin, "Flux Pinning Under the Strong Electrostatic Field in the BiPbSrCaCuO Film." To be published in Physica C (in press). Institute of Semiconductor Physics, National Academy of Sciences of Ukraine, 45 Prosp. Nauki, 252650 Kiev, UKRAINE; telephone +380 44 265 5069; telefax +380 44 265 8342; e-mail lys@cryo.semicond.kiev.ua. Key words: flux pinning, pinning potential, electric field effect.
R. Mallozzi, J. Corson, J. Orenstein, J. N. Eckstein, and I. Bozovic, "Terahertz Conductivity and c-Axis Plasma Resonance in Bi2Sr2CaCu2O8+d." University of California at Berkeley and Lawrence Berkeley National Laboratory, Berkeley, CA 94720.
J. H. Miller, Jr. and J. R. Claycomb, "Classical and High Temperature Superconductivity." Preprint #97:091; to be published in Proc. of the Summer School Workshop on Cond. Mat. Phys., Canberra, Australia, Feb. 1997, edited by M. P. Das. Texas Center for Superconductivity, University of Houston, Houston, TX 77204-5932; telephone (713) 743-8200; telefax (713) 743-8201; e-mail preprints@www.tcs.uh.edu.
O. V. Misochko, K. Kuroda, and N. Koshizuka, "Superconducting Gap Anisotropy and Phonon Anomalies in Single Crystal NdBa2Cu3O7-x." To be published in Phys. Rev. B. Institute of Solid State Physics, Russian Academy of Sciences, 142432 Chernogolovka, Moscow Region, RUSSIA; e-mail misochko@issp.ac.ru. 78.30.-j; 63.20.Kr.
N. Miyakawa, P. Guptasarma, J. F. Zasadzinski, D. G. Hinks, and K. E. Gray, "Strong Dependence of the Superconducting Gap on Oxygen Doping from Tunneling Measurements on Bi2Sr2CaCu2O8-x." Submitted to Phys. Rev. Lett. Contact Janice Coble, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439; telefax (708) 252-9595; e-mail janice_coble@qmgate.anl.gov. 74.50.+r; 74.62.Dh; 74.72.Hs; 74.25.Dw.
B. H. Moeckly and K. Char, "Properties of Interface-Engineered High-Tc Josephson Junctions." Submitted to Appl. Phys. Lett. Conductus, Inc., 969 W. Maude Avenue, Sunnyvale, CA 94086; e-mail moeckly@conductus.com.
B. H. Moeckly, K. Char, Y. Huang, and K. L. Merkle, "Interface- Engineered High-Tc Josephson Junctions." Submitted to Appl. Supercond: Proc. of the 6th Int. Supercond. Electronics Conf. (ISEC'97), Berlin, Germany, June 26-28, 1997. Conductus, Inc., 969 W. Maude Avenue, Sunnyvale, CA 94086; e-mail moeckly@conductus.com.
B. Morosin, E. L. Venturini, R. G. Dunn, and P. P. Newcomer, "On Tl-1212 Superconductor Single Crystals: Structure and Magnetism Changes on Annealing." To be published in Physica C (in press). Sandia National Laboratories, Albuquerque, NM 87185-1421; telefax (505) 844-4045.
R. Mulet and E. Altshuler, "Avalanche Behavior in One-Dimensional Superconductors with a Periodic Distribution of Pinning Centers: A Monte Carlo Approach." To be published in Physica C (in press). Contact E. Altshuler, Superconductivity Laboratory, IMRE-Physics Faculty, University of Havana, 10400 La Habana, CUBA; e-mail jea@informed.sld.cu.
Sang Boo Nam, "Magnetic Penetration Depth in a Superconductor." University Research Center, Wright State University, 7735 Peters Pike, Dayton, OH 45414 and Department of Physics, Pohang University of Science and Technology, Pohang, Kyungbook 790-784, KOREA; e-mail sbnam@galaxy.postech.ac.kr; preprint also available at cond- mat@xxx.lanl.gov (#9708119). 74.25.Ha; 74.20.Fg.
S. Nhien and P. L. Langlois, "Quantitative Analysis of Grain Alignment in Ceramic Bi-2223 Superconductor Powder by Pressure-Assisted Compression." To be published in Physica C (in press). Laboratoire de PhysicoChimie des Materiaux, CNRS-UPR 211, 1 place Aristide Briand, F- 92195 Meudon Cedex, FRANCE; telephone +33 1 4507 5050; telefax +33 1 4507 5336. Key words: bismuth-based high-Tc superconductors, texturation, materials treatment effects on plasticity, high-pressure techniques. 74.72.Hs; 81.40.Ef; 81.40.Lm; 07.35.+k.
M. Oda, K. Hoya, R. Kubota, C. Manabe, N. Momono, T. Nakano, and M. Ido, "Strong Pairing Interactions in the Underdoped Region of Bi2Sr2CaCu2O8+d." To be published in Physica C (in press). Department of Physics, Faculty of Science, Hokkaido University, Sapporo 060, JAPAN; telephone +81 11 706 3575; telefax +81 11 746 5444; e-mail katuhiko@s2.hines.hokudai.ac.jp. Key words: Bi-based high-Tc cuprate, STM/STS, superconducting gap, pairing interaction, antiferromagnetic correlation.
J. H. Park, D. H. Kim, S. Y. Shim, Y. H. Kim, J. M. Lee, T. S. Hahn, J. D. Hettinger, D. G. Steel, K. E. Gray, B. Glagola, J. Lee, and Z. G. Khim, "Enhanced Transport Properties in YBa2Cu3Ox Films with Crossed Columnar Defects of Various Inclination Angles." To be published in Physica C (in press). Korea Institute of Science and Technology, Seoul 131-791, SOUTH KOREA; telefax +82 53 813 4465; e-mail dhkim@ynucc.yeungnam.ac.kr.
Ravi S. Prasher and Patrick E. Phelan, "Review of Thermal Boundary Resistance of High-Temperature Superconductors." To be published in J. Supercond. Contact Patrick E. Phelan, Department of Mechanical and Aerospace Engineering, Arizona State University, P.O. Box 876106, Tempe, AZ 85287-6106; telephone (602) 965-1625; telefax (602) 965-1384; e-mail phelan@asu.edu. Key words: thermal boundary resistance, high- temperature superconductors.
Rachel M. Quick and Sergei G. Sharapov, "Persistence of Pseudogap Formation in Quasi-2D Systems with Arbitrary Carrier Density." Department of Physics, University of Pretoria, 0002 Pretoria, SOUTH AFRICA; Sergei G. Sharapov's e-mail sharapov@scientia.up.ac.za; preprint also available at cond-mat@xxx.lanl.gov (#9708151). 74.72.-h; 74.20.Fg; 74.20.Mn; 64.60.Cn.
E. Sudhakar Reddy, "Microstructural Studies of Melt Processed REBa2Cu3Oy (RE=Y,Gd) Superconductors and a Process for Their Near-Net Shape Fabrication." Submitted as a Ph.D. thesis (University of Hyderabad). SSP Group, Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400 005, INDIA; telephone +91 22 215-2971 or -2979, ext. 2439; telefax +91 22 215-2110 or -2181; e-mail esreddy@tifrvax.tifr.res.in.
M. S. Rzchowski and B. M. Hinaus, "Critical-Current Measurements in Planar Josephson Junctions." Department of Physics and Applied Superconductivity Center, University of Wisconsin-Madison, Madison, WI 53706. 74.50.+r; 74.76.Bz; 74.60.Jg.
T. Saitoh, K. Segawa, K. Kamada, N. Sakai, T. Segawa, S. I. Yoo, and M. Murakami, "Microstructures and Superconducting Properties of Melt- Processed (RE,RE')-Ba-Cu-O." To be published in Physica C (in press). Contact N. Sakai, Superconductivity Research Laboratory, International Superconductivity Technology Center (ISTEC), 1-16-25 Shibaura, Minato- ku, Tokyo 105, JAPAN; telephone +81 3 3454 9284; telefax +81 3 3454 9287; e-mail nsakai@istec.or.jp. Key words: (RE,RE')-Ba-Cu-O, superconductor, melt-processing, low oxygen partial pressure, decomposition temperature. 74.72.Bk; 74.80.Bj; 74.60.Jg.
Osvaldo F. Schilling, Luis Ghivelder, and I. Abrego Castillo, "Linearized Description of the ac Susceptibility of Ceramic High-Tc Superconductors." To be published in Supercond. Sci. & Technol. Departamento de Fisica, Universidade Federal de Santa Catarina, Campus, Trindade, 88040-900 Florianopolis, Santa Catarina, BRAZIL.
Fan Shi, "New Superconducting Phase Diagram of YBa2(Cu1-xFex)3Oy and Consequences on Mechanism of High-Tc Superconductivity." Submitted as a Master of Science thesis (University of Cincinnati). Department of Electrical & Computer Engineering and Computer Science, University of Cincinnati, P.O. Box 210030, Cincinnati, OH 45221-0030; telephone (513) 281-7688; e-mail fshi@ececs.uc.edu.
Hajime Shimizu, Kunihiko Fujiwara, and Kenji Hatada, "Er^[3+]-EPR Study of Er-Doped LSCO: Magnetic and Electronic Properties of La2-xSrxCuO4 as Studied by EPR of Er Spin Probes." To be published in Physica C (in press). Department of Electronics and Computer Science, Science University of Tokyo in Yamaguchi, Onoda, Yamaguchi 756, JAPAN; telephone +81 836 884545; telefax +81 836 883844. Key words: high-Tc superconductor, substitutional effect, LSCO, EPR, orbit-lattice coupling.
M. Shinkawa, H. Utsunomiya, T. Sakai, and Y. Saito, "Critical Current Density of Ag-Sheathed (Bi,Pb)2223 Tapes Produced by Various Thermomechanical Treatment Patterns." To be published in Physica C (in press). Department of Materials Science and Engineering, Faculty of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565, JAPAN; telephone +81 6 879 7502; telefax +81 6 879 7936; e-mail shinkawa@mat.eng.osaka-u.ac.jp. Key words: thermomechanical treatment, Bi(2223) tape, critical current density, texture.
German Sierra, Miguel Angel Martin-Delgado, Jorge Dukelsky, Steven R. White, and D. J. Scalapino, "The Dimer-Hole-RVB State of the 2-Leg t-J Ladder: A Recurrent Variational Ansatz." Instituto de Matematicas y Fisica Fundamental, C.S.I.C., 28006 Madrid, SPAIN; e-mail sierra@sisifo.imaff.csic.es; preprint also available at cond- mat@xxx.lanl.gov (#9707335).
J. E. Sonier, J. H. Brewer, R. F. Kiefl, D. A. Bonn, S. R. Dunsiger, W. N. Hardy, Ruixing Liang, W. A. MacFarlane, R. I. Miller, T. M. Riseman, D. R. Noakes, C. E. Stronach, and M. F. White, Jr., "muSR Measurement of the Fundamental Length Scales in the Vortex State of YBa2Cu3O6.60." Submitted to Phys. Rev. Lett. Department of Physics and Astronomy, University of British Columbia, Vancouver, B.C., CANADA V6T 1Z1; telephone (604) 822-6520; telefax (604) 822-5324; e-mail sonier@triumf.ca; preprint also available at cond-mat@xxx.lanl.gov (#9708115).
E. Suard, I. Mirebeau, V. Caignaert, P. Imbert, and A. M. Balagurov, "Influence of a Deoxygenation Process on the Magnetic Diagram of Iron Doped YBa2Cu3Oy Phases: A Neutron Diffraction Study." To be published in Physica C (in press). Institut Laue-Langevin, BP 156X, F-38042 Grenoble, FRANCE; telefax +33 1 6908 6989; e-mail mirebea@bali.cea.saclay.fr. Key words: high-Tc compounds, neutron diffraction, magnetic phase diagram. 61.12.Ld; 74.25.Ha; 74.72.Bk; 75.30.Kz; 61.18.Fs.
Kimihito Tagaya, Takayuki Yokoo, Takumi Fujita, and Nobuo Fukuoka, "Microwave Magnetoabsorptions of YBa2Cu3Oy Single Crystal." To be published in Physica C (in press). Department of Materials Science, Osaka Prefecture University, Gakuen-cho 1-1, Sakai, Osaka 593, JAPAN; telephone +81 722 521161; telefax +81 722 552981; e-mail tagaya@cias.osakafu-u.ac.jp. Key words: microwave magnetoabsorption, YBa2Cu3Oy, lower critical field, Y2BaCuO5, superparamagnetism.
A. Thamizhavel, D. P. Paul, D. Prabhakaran, R. Jayavel, and C. Subramanian, "Studies on Simultaneous Substitution of Pb and Y in Bi2Sr2CaCu2O8+d Single Crystals." To be published in Physica C (in press). Contact C. Subramanian, Crystal Growth Centre, Anna University, Madras 600 025, INDIA; telefax +91 44 235 2774; e-mail crystal@sirnetm.ernet.in. Key words: surface morphology, etching, substitutional study, susceptibility, twins.
S. P. Tirumala, D. F. Lee, D. M. Kroeger, and K. Salama, "Effects of Stoichiometric Variation and Cooling Rate on the Phase Formation and Critical Current Density of Bi-2223 Powder-In-Tube Tapes Made from Aerosol Precursor." Preprint #97:090; submitted to Supercond. Sci. & Technol. 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.
T. Tsuboi, T. Hanaguri, and A. Maeda, "Local Density Fluctuations of the Moving Vortices in the Solid and Liquid Phases in Bi2Sr2CaCu2Oy." Submitted to Phys. Rev. Lett. Department of Basic Science, University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153, JAPAN; telephone +81 3 5454 6763; telefax +81 3 3467 8945; e-mail cc67913@komaba.ecc.u- tokyo.ac.jp. 74.60.Ge; 74.25.Bt; 74.25.Fy; 74.72.Hs.
M. Ullrich, A. Leenders, H. C. Freyhardt, J. H. Albering, and S. Gauss, "Large Grained YBCO Monoliths for Magnetic Bearings of a LH2Tank." To be published in the Proc. of the 3rd European Conf. on Appl. Supercond. (EUCAS'97), Veldhoven, The Netherlands, June 30-July 3, 1997. Zentrum fuer Funktionswerkstoffe gGmbH Goettingen, Windausweg 2, D-37073 Goettingen, GERMANY; telephone +49 551 50717 30; telefax +49 551 50717 50; e-mail ullrich@umpsun1.gwdg.de.
N. Vandewalle, M. Ausloos, and R. Cloots, "Formation of Nick Instabilities Due to Particle Clustering Along Crystal Interfaces." To be published in Phys. Rev. E. SUPRAS, Institute of Physics B5, University of Liege, B-4000 Liege, BELGIUM; e-mail vandewal@gw.unipc.ulg.ac.be; Web site http://www.phe.ulg.ac.be/. 05.40.+j; 61.50.Cj.
N. Vasanthamohan, J. P. Singh, G. Khanna, and M. T. Lanagan, "Stress/Strain Performance of Sheathed Bismuth-2223 Superconductors." Submitted to the Proc. of the 1997 Annual Meeting of the Amer. Ceram. Soc., Cincinnati, Ohio. Contact Janice Coble, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439; telefax (708) 252-9595; e-mail janice_coble@qmgate.anl.gov.
N. Vasanthamohan, J. P. Singh, and K. A. Lubke, "Strain Tolerance of Ag- Sheathed BSCCO (2223) Superconductors with Various Geometrical Configurations." Submitted to Supercond. Sci. & Technol. Contact Janice Coble, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439; telefax (708) 252-9595; e-mail janice_coble@qmgate.anl.gov.
M. Vedawyas, A. Bhagwat, G. Marest, and H. Jaffrezic, "Site Characterization of [57]^Fe Implanted in Epitaxial Thin Films of Y1Ba2Cu3O7-d by Conversion Electron Mossbauer Technique." To be published in Physica C (in press). Contact A. Bhagwat, Department of Physics, University of Pune, Pune 411 007, INDIA; e-mail postmaster@physics.unipune.ernet.in.
C. Weber, F. Kahlmann, J. Schubert, W. Zander, B. Kabius, U. Breuer, and Ch. Buchal, "Growth of YBa2Cu3O7-d on Co Implanted Substrates." To be published in Physica C (in press). Contact F. Kahlmann, Institut fuer Schicht- und Ionentechnik, Forschungszentrum Juelich, D-52425 Juelich, GERMANY; telephone +49 2461 614 486; telefax +49 2461 614 673; e-mail f.kahlmann@kfa-juelich.de.
W. C. Wu and J. P. Carbotte, "Universal Zero-Frequency Raman Slope in a d-Wave Superconductor." Submitted to Phys. Rev. Lett. Department of Physics and Astronomy, McMaster University, Hamilton, Ontario, CANADA L8S 4M1; telephone (905) 525-9140, ext. 23182; telefax (905) 546-1252; e-mail wu@physics.mcmaster.ca; preprint also available at cond- mat@xxx.lanl.gov (#9708077). 78.30.-j; 74.62.Dh; 74.25.Gz.
H. Yamamoto, M. Naito, and H. Sato, "Surface Stability of MBE-Grown Nd1.85Ce0.15CuO4 Thin Films in Air Investigated by RHEED, XPS, and UPS." To be published in Physica C. MATSUDA Research Group, NTT Basic Research Laboratories, 3-1 Wakamiya, Morinosato, Atsugi-shi, Kanagawa 243-01, JAPAN; telephone +81 462 40 3523; telefax +81 462 70 2364; e- mail hideki@will.brl.ntt.co.jp. Key words: surface stability, MBE- grown Nd1.85Ce0.15CuO4 film, RHEED, XPS, UPS. 79.60.Dp; 74.76.Bz; 81.15.Hi; 74.72.Jt.
Jian Ding Yu, Satoshi Sasaki, Hiroshi Sugiura, Tongkai Huang, Yoshiyuki Inaguma, and Mitsuru Itoh, "Compressibility and Pressure Dependence of Charge Transfer and Tc in Pristine and Iodine-Intercalated Single Crystals of Bi2.2Sr1.8CaCu2O8+d." To be published in Physica C (in press). Contact Mitsuru Itoh, Materials and Structures Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226, JAPAN. Key words: electrical resistivity, Hall concentration, high- pressure effect.
M. Zamboni, S. I. Yoo, T. Higuchi, K. Waki, S. Koishikawa, and M. Murakami, "Magneto Optical Characterizations of Flux Dynamics in Nd-Ba- Cu-O Bulk Superconductors." To be published in Physica C (in press). Superconductivity Research Laboratory Division 7, International Superconductivity Technology Center (ISTEC), 1-16-25 Shibaura, Minato- ku, Tokyo 105, JAPAN; telephone +81 3 3454 9284; telefax +81 3 3454 9287; e-mail monica@istec.or.jp. Key words: flux dynamics, Nd-Ba-Cu-O superconductors, magneto optical technique, anisotropy, iron-garnet films. 74.60.Ge.
B. Zeimetz, G. E. Murashova, H. K. Liu, and S. X. Dou, "Preparation of Bi2223 Precursor Powders by Sintering in Low Oxygen Partial Pressure." Presented at the 3rd European Conf. on Appl. Supercond. (EUCAS'97), Veldhoven, The Netherlands, June 30-July 3, 1997. Centre for Superconducting and Electronic Materials, University of Wollongong, Wollongong NSW 2522, AUSTRALIA; telephone +61 42 215766; telefax +61 42 215731; e-mail bpz01@uow.edu.au.
X. Y. Zhou, Z. Zhu, L. H. Zhai, and R. D. Han, "A Positron Lifetime Study on Y1-xPrxBa2Cu3O7-d." To be published in Physica C (in press). Department of Modern Physics, University of Science and Technology of China, P.O. Box 4, Hefei 230027, PEOPLE'S REPUBLIC OF CHINA; telephone +86 551 360 1176; telefax +86 551 360 1164; e-mail zhouxy@lx04.mphy.ustc.edu.cn. 74.72.Bk; 78.70.Bj.
COMING EVENTS (An * indicates a previously listed event.)
Feb. 15 - 19, 1998: 1998 TMS Annual Meeting -- 127th Annual Meeting of The Minerals, Metals & Materials Society, Henry B. Gonzalez Convention Center, San Antonio, Tex. Technical presentations, short courses, exhibition, social functions, and a variety of special events. Event will provide a near-comprehensive overview of cutting-edge progress in primary processing, fabrication, application, and economic developments for aluminum, copper, titanium, steel, and other key materials, including superalloys, ceramics, superconductors, composites, polymers, and electronic materials. International exhibition featuring more than 250 booths displaying new technology, materials, products, and services. For more information, contact TMS Customer Service, TMS, 420 Commonwealth Drive, Warrendale, PA 15086-7514; telephone (U.S. only) (800) 759-4867 or (412) 776-9000, ext. 270; telefax (412) 776-3770; e- mail csc@tms.org.
Feb. 19 - 24, 1998: First International Conference on New Theories, Discoveries, and Applications of Superconductors and Related Materials (New3SC-1), Baton Rouge, La. Call for papers. Purpose of conference is to attempt to determine if "a radical change is needed in the fundamental approach to superconductivity, or if the conventional approaches are likely to bear fruit soon." Conference will focus on new ideas and measurements, concepts, and models of the mechanism and origin of high-temperature superconductivity. Discussion time will be provided throughout the conference. Subjects include superconductors, giant magnetoresistance, and ferroelectric materials. Abstract deadline, December 15, 1997; early-bird registration deadline, October 15, 1997. For further information, contact J. D. Fan, Chairman New3SC, P.O. Box 9767, Baton Rouge, LA 70813-9767; telephone (504) 771-3926; telefax (504) 771-3926; e-mail new3sc@grant.phys.subr.edu; Web site http://www.phys.subr.edu/conference/new3sc.htm.
*March 24 - 29, 1998: The International Workshop on High Temperature Superconductors and Novel Inorganic Materials Engineering (MSU-HTSC V), Moscow, Russia. Workshop will be the fifth in the series organized by Moscow State University since 1989. Main topics: chemistry and technology of superconducting materials and novel inorganic materials engineering. Abstract deadline, December 15, 1997. For further information, contact A. I. D'yachenko, MSU-HTSC V Secretariat, Department of Chemistry, Moscow State University, Moscow 119899, Russia; telephone +7 095 939-34-90; telefax +7 095 939-47-88; e-mail dyachenko@inorg.chem.msu.su.
June 7 - 12, 1998: European Conference on Energy Dispersive X-ray Spectrometry 1998 (EDXRS-98), Aula Prodi, San Giovanni in Monte, Bologna, Italy. Aim is to bring together experts and users of energy dispersive x-ray spectrometry working either in basic research in x-ray spectrometry, detectors and sources, or applications of x-ray spectrometry. The official language of the conference is English. Topics are: interactions of x-rays with matter and their modeling; special applications of polarized radiation (synchrotron radiation, x- ray astrophysics); conventional techniques (XRF, PIXE, sample preparation); advances in x-ray spectrometry (advanced spectrometers); data handling and instrumentation (quantitation procedures and software, x-ray sources, beam techniques); energy dispersive x-ray detectors; microanalysis with photon sources (m-XRF); microanalysis with charged particles (m-PIXE, EPMA); x-ray optics, TXRF and capillarity; specific applications (archeometry, environmental, medicine, and material testing). Preregistration deadline, November 1, 1997; abstract deadline, March 15, 1998. Selected papers presented at the conference will be printed in a special issue of the International Journal of X-Ray Spectrometry. For information, contact Barbara Cavallari, Organizing Secretariat, Laboratario delle IDEE Srl, Via S. Stefano 32, I-40125 Bologna, Italy; telephone +39 51 261440; telefax +39 51 265742; Web site http://www.ing.unibo.it/Eventi/edxrs98/welcome.html.
*June 14 - 19, 1998: Ninth International Conference on Modern Materials & Technologies (CIMTEC '98): Topical Symposium VI -- Science and Engineering of HTC Superconductivity, Florence International Congress Centre, Florence, Italy. Will highlight recent research advances in high-Tc oxide, organic, and other exotic superconductors. Fundamental aspects and theory, advances in materials synthesis, processing and properties will be featured as well as current developments in superconducting components and devices. Session topics are broadly classified in to the following groups: materials, synthesis, processing, structure, and physical chemistry; physical properties; phenomenology of the superconducting state; theory of HTC superconductivity; and applications. Oral and poster presentations. Abstract deadline, September 30, 1997. Proceedings to be published. Official language is English. Contact 9th CMTEC, Forum on New Materials, Topical Symposium VI, P.O. Box 165, I-48018 Faenza, Italy; telephone +39 546-22661 or -664143; telefax +39 546-664138 or -663362.
RESOURCES
Information
Books: Bismuth-Based High-Temperature Superconductors, edited by Hiroshi Maeda and Kazumasa Togano. Comprehensive reference provides detailed coverage of the ongoing investigations on bismuth-based high- temperature cuprate superconductors -- integrating scattered research activities and literature from 70 leading scientists throughout the world. The book covers crystal structures and microstructures; reversible or equilibrium magnetic and thermal properties; atomic site tunnel spectroscopy; experimental studies concerning equilibrium phases; intrinsic pinning phenomena in layered cuprate superconductors; the synthesis process of calcined powder; the formation of 2212 and 2223 phases in the BSCCO system through the diffusion reaction; the preparation and properties of tape and round wires; fabrication, microstructure, and superconducting properties of Bi-2212 tapes; and more. Publ. July 1996; 648 pp.; price $250; ISBN 0-8247-9690-X.
Thallium-Based High-Temperature Superconductors, edited by Allen M. Hermann and J. V. Yakhmi. Provides up-to-date information on all physical, chemical, and materials aspects and applications of this class of cuprates. 640 pp.; price $195; ISBN 0-8247-9114-2.
For information, contact Promotion Department, Marcel Dekker, Inc., 270 Madison Ave., New York, NY 10016; telephone (800) 228-1160 or 696-9000; telefax (914) 796-1772; Web site http://www.dekker.com.
FYI (High-Tc Update takes no responsibility for want ads listed in this section.)
Position open: A postdoctoral position is immediately available to carry out research on fundamental and applied microwave superconductivity. Specialization in superconductivity is required; additional experience in rf and microwave measurements strongly preferred. Applications, including a resume and names of at least three references, should be sent to Prof. S. Sridhar, Department of Physics, Northeastern University, 360 Huntington Avenue, Boston, MA 02115; telephone (617) 373-2930; telefax (617) 373-2943; e-mail srinivas@neu.edu; Web site http://sagar.physics.neu.edu.
Positions open: Postdoctoral positions are available in the field of condensed-matter theory at the International Center for Theoretical Physics (Trieste). Current research areas include strongly correlated electron systems, disordered and mesoscopic systems, ab-initio electronic structure studies, surface physics, statistical physics, and complex systems. Year-long appointments available starting fall 1998, with possibility of renewal for a second year. Salary: About Lit. 2,260,000/mo. or higher depending on seniority. Travel allowance. Application deadline, December 31, 1997. Send application including detailed curriculum vitae, list of publications, and letters of recommendation to Condensed Matter Secretary, ICTP, P.O. Box 586, I- 34100 Trieste, Italy.
Position wanted: Recent Ph.D. with experience in melt-processing and microstructural studies of RE-123 superconductors seeks suitable position. Contact E. Sudhakar Reddy, SSP Group, Tata Institute of Fundamental Research, Homi Bhaba Road, Colaba, Mumbai 400 005, India; telephone +91 22 215-2971 or -2979, ext. 2439; telefax +91 22 215-2110 or -2181; e-mail esreddy@tifrvax.tifr.res.in.
Internet Bookshop recently introduced by World Scientific Publishing Co., Inc. Over 800 titles currently available on the Web for browsing. The URL is http://www.wspc.com.sg/.
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Project Director/Editor: Sreeparna Mitra Science Editor: John R. Clem High-Tc Update, Vol. 11, #18, September 15, 1997.