HIGH-Tc UPDATE E-MAIL VERSION, VOL. 11, NO. 17, Sept. 1, 1997.

Published for the Division of Materials Sciences, Office of Basic Energy Sciences, USDOE, under Contract W-7405-eng-82 with the Ames Laboratory, Iowa State University. Funded by DMS/BES/USDOE, ARPA, ONR, NSF, and other agencies, organizations, and individuals.

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Vortices

Magnetic and transport measurements by K. Deligiannis (Southampton) et al. reveal that the magnetization-peak line H_p(T) in the phase diagram of single-crystal YBa2Cu3O7-d exhibits strong similarities to the corresponding second-peak line in Bi2Sr2CaCu2O8+d. The results show a similar temperature dependence, an almost identical response to oxygen doping, and a similar correlation with the multicritical point at which the vortex-lattice melting line changes from first to second order. The results support the picture that H_p(T) separates a weakly disordered vortex quasilattice for H < H_p(T) and a highly disordered entangled solid for H > H_p(T).

The pinning of vortices by a spatially periodic array of pinning centers has been experimentally investigated by J. I. Martin et al. (UC-San Diego). Using electron-beam lithography, the authors fabricated triangular arrays of submicrometer magnetic dots, with typical spacing of 400-600 nm and diameters close to 200 nm, to study pinning effects on Nb thin films. Curves of the resistivity versus magnetic field exhibit regular structure, with minima appearing at constant field intervals, given by the lattice parameter of the dot array.

Vortex-line equilibrium configurations and critical currents at zero temperature for type-II superconducting films carrying a current perpendicular to a parallel applied field have been studied theoretically by G. Carneiro (Rio). The author finds that the equilibrium configurations consist of chains of straight vortex lines whose number depends on both the field and the current. Transitions involving a change by one in the chain number take place if either the field is increased at zero transport current or the transport current is increased at constant field.

The ohmic and Hall flux-flow conductivities in the mixed state of clean d-wave superconductors have been calculated by Yu. G. Makhlin (Illinois-Urbana and Landau Institute) taking into account the spectral flow along the anomalous branch of the states bound to vortex cores. Three regimes of vortex dynamics are obtained, depending upon the ratio of the width of the localized levels 1/tau to (a) the interlevel spacing in the core and (b) Delta_0^2/E_F.

A preprint by G. E. Volovik (Helsinki and Landau Institute) points out that the Magnus force on vortices in Josephson-junction arrays is small because the parameter of the particle-hole asymmetry in superconductors is of order Delta^2/E_F^2 << 1.

Monte Carlo calculations of the resistivities in isotropic type-II superconductors for transport currents both perpendicular (R_[xx] = R_[yy]) and parallel (R_[zz]) to the vortex direction in the presence of strong thermal fluctuations have been carried out by T. J. Hagenaars (Wuerzburg) and E. H. Brandt (MPI-Stuttgart). For the finite system size considered, the authors find that the vortex-lattice melting transition occurs in two steps. As the temperature increases, the structure factor drops to zero and R_[xx] becomes finite at temperature T_m. At a higher temperature T_z, longitudinal superconducting coherence is lost and R_[zz] becomes finite.

To study relaxation dynamics of the two-dimensional XY gauge glass, B. J. Kim (Seoul National) et al. have included thermal noise currents and numerically integrated the equations of motion for an L x L square array of resistively shunted Josephson junctions. At low but nonzero temperatures, the relaxation exhibits an algebraic relaxation. The average relaxation time is well described by tau ~ (T - T_g)^[-b], where T_g is the glass temperature and b = 0.76+-0.05, strongly suggesting a finite-temperature glass transition. At high temperatures, the relaxation can be explained in terms of the annihilation of unpinned vortices.

The dynamics of dislocations in a two-dimensional vortex lattice in the presence of a pinning potential and a transport current has been studied by S. Scheidl (Koeln) and V. M. Vinokur (Argonne). The authors find a crossover between two regimes, one where dislocations are pinned by impurities and another where dislocations move coherently with the vortex lattice.

Three preprints by F. Bass et al. (Bar-Ilan) report on various aspects of the nonlinear dynamics of magnetic-flux (vortex) penetration into type-II superconductors. In one of these papers, the authors analyze an instability caused by the positive feedback between the front heating and vortex diffusion in the superconductor, which leads to a spatially inhomogeneous flux state in the sample.

A general class of type-II superconductors described by N complex order parameters with an overall symmetry U(N) for the energy functional has been considered by M. A. Moore et al. (Manchester). The authors present detailed results for the vortex structure for the case N = 2. The results differ from the well-studied, conventional case for which N = 1. The authors also consider the case of N --> infinite, for which the U(N) model undergoes a continuous transition from the normal to the mixed state.

ac Losses

Measurements of the ac losses in two one-meter-long lengths of HTS prototype multistrand conductors (PMC's) have been made by D. E. Daney (Los Alamos) et al. using a temperature-difference calorimeter. Both single-phase and three-phase losses have been examined with currents up to 1000 A rms. The measured losses show no significant effect of interlayer insulation and depend on about the third power of the current, a result in agreement with the Bean model adapted to the double-helix configuration. The three-phase losses are a factor of two higher than those exhibited by a single isolated conductor, indicating a significant interaction between phases.

The magnetic-field and current distributions inside thin superconducting strips arranged in a z-stack and an x-array have been calculated by K.-H. Mueller (CSIRO) using the transformation method proposed by Y. Mawatari [Phys. Rev. B 54, 13215 (1996)] for the case where a transport current is passed through the strips. The magnetic field distributions are used to calculate the self-field ac hysteretic losses of both the z-stack and the x-array. The author finds that the self-field ac hysteresis loss of the z-stack is always larger than that of the x-array.

The hysteresis loss in the superconductor and the eddy current loss in the metal substrate of a YBCO/hastelloy flexible tape have been calculated analytically by K.-H. Mueller (CSIRO) in the low-frequency limit. The author studied the cases where (a) an ac transport current is passed through the tape and (b) an external ac magnetic field is applied perpendicular to the tape.

A method for the measurement of transport ac losses in superconducting wire rings is described in a preprint by A. N. Terentiev et al. (KAERI). The method is based on the measurement of the quality factor of a mechanical resonator composed of a stainless-steel cantilever with a permanent magnet at the free end.

RBa2Cu3O7-d

A structural phase transformation in the CuO2 planes of YBa2Cu3Ox is reported by E. Kaldis (Zurich) et al. at the onset of the overdoped regime, x = 6.95. The authors' results support the ideas that the dimpling of the CuO2 planes is an intrinsic property of the superconducting cuprates and that local coherent distortions of the CuO2 planes and superconductivity are coupled.

Reversible magnetic-torque measurements by T. Ishida (Osaka Prefecture University) et al. in untwinned, single-crystal YBa2Cu3O7-d have revealed both two-fold and four-fold symmetry in the ab plane. The authors report the anisotropy parameters gamma_[ca] = (m_c/m_a)^[1/2] = 7.55+-0.63, gamma_[cb] = (m_c/m_b)^[1/2] = 8.95+-0.76, and gamma_[ab] = (m_a/m_b)^[1/2] = 1.18+-0.14. However, in addition to the two-fold-symmetric component of the torque expected from anisotropic London theory, the authors also measured a four-fold-symmetric component, which is consistent with theoretical expectations for d_[x^2-y^2] order-parameter symmetry.

An infiltration and growth process for the fabrication of RBa2Cu3O7-d (R = Y, Gd, Sm, and Nd) superconductors with highly textured microstructure is described by E. S. Reddy and T. Rajasekharan (Hyderabad).

A paper by L. Colonescu et al. (Orsay) shows that an insulator-to-superconductor transition can be induced in the insulating compound Tm0.4Pr0.6Ba2Cu3O7-d by isovalent substitution at the Ba site by Sr. The authors suggest that some of the factors favoring such a transition are changes produced in structural parameters, reduced hybridization between Pr f states and O p orbitals, and an increase in oxygen ordering.

Bi Cuprates

Angle-resolved photoemission spectroscopy (ARPES) has been used by M. R. Norman (Argonne) et al. to investigate the pseudogap regime (Tc < T < T*) of underdoped Bi2Sr2CaCu2O8+d (Bi-2212). The authors report that the electron-electron interactions increase strongly as the doping is reduced, leading to a smaller quasiparticle peak in the superconducting state and a much broader lineshape in the normal state. The pseudogap phase above Tc in underdoped materials is characterized by the disappearance of quasiparticle peaks but with the spectral gap still present. This gap, however, closes at different temperatures for different momenta, leading to the formation of gapless arcs above Tc which expand in length until the entire Fermi surface is recovered at T*.

Tunneling spectroscopy measurements on single crystals of Bi2Sr2CaCu2O8+d (Bi-2212) have been carried out by Y. DeWilde (Argonne) et al. using vacuum tunneling and point-contact methods. The authors found a reproducible dip feature in the tunneling conductance near |eV| = 2[Delta] for both voltage polarities in the best resolved spectra. With overdoping, the position of the dip continues to scale with Delta, and its magnitude decreases as Delta decreases. The results indicate that the dip feature arises from a strong-coupling effect whereby the quasiparticle lifetime is decreased at a characteristic energy of ~2[Delta], consistent with an electron-electron pairing mechanism.

The products of two crystallization paths in the Bi-Sr-Ca-Cu-O system, based on the experimentally determined Bi2Sr2CaCu2O8+d (Bi-2212) primary phase field, are reported by L. P. Cook and W. Wong-Ng (NIST-Gaithersburg). The results demonstrate the importance of careful control of the cooling history and bulk composition during processing of Bi-2212.

Two related papers by W. Wong-Ng (NIST-Gaithersburg) et al. report on subsolidus-phase relationships in the (Bi,Pb)-Sr-Ca-Cu-O system. The ultimate goal of this research is to construct the primary phase field of the 110 K (Bi,Pb)2Sr2Ca2Cu3O10+d [(Bi,Pb)-2223] superconductor. The authors explored the compositional space containing the 2223 and 2212 pair, and they report that eleven phases can exist in equilibrium with the 2223 phase.

As reported by M. Aleksa (TU Wien) et al., several high-quality single crystals of superconducting Bi-2212 in the form of single crystals and pre-characterized TEM samples were exposed to three different neutron fluences and then studied via TEM to characterize the resulting radiation damage. The authors found that the damage produced in Bi-2212 is very similar to that found previously in YBa2Cu3O7-d single crystals. The authors conclude that neutron-induced defects in high-Tc materials generally have a diameter of 5-7 nm, including the strain field.

A paper by Y. Xu (Argonne and Mankato State) et al. reports experiments in which nanometer-scale oxide inclusions were added to Bi2Sr2CaCu2O8+d (Bi-2212) superconductors to determine their effectiveness in creating intragranular flux-pinning sites. The authors found that Al2O3 additions exhibited the most promise for forming stable pinning centers, while ZrO2 and SnO2 were moderately promising, TiO2, Fe2O3, and ZnO were less promising, and Y2O3 destroyed superconductivity.

Magnetization hysteresis loops of a rolled Bi-2223/Ag tape have been measured by P. Nalevka (Praha) et al. To separate the inter- and intragranular current contributions, the authors bent the tape to a small diameter and repeated their measurements after straightening. Significant intergranular current hysteresis was observed for increasing and decreasing fields at low temperatures.

Other Cuprates

Flux-creep measurements in HgBa2Ca2Cu3O8+d (Hg-1223) ceramics are reported by M. Reissner (Wien). From an analysis of the magnetic relaxation measurements, the author concluded that both surface and bulk pinning is evident. To investigate the influence of aging, the author also repeated the measurements after four and twelve months. Destruction of the grain-boundary superconducting properties and degradation of the grain surfaces were found.

An increase in the magnetic, quasi-triplet average ground-state splitting of Pr in Pb2Sr2Pr0.5Ca0.5Cu3O8 (Tc = 60 K) relative to that in the parent, Ca-free compound has been observed by U. Staub (PSI) et al. using inelastic neutron scattering. The results suggest that pair-breaking is the cause of Tc suppression in Pr-based compounds.

A detailed study of the ab-plane reflectance of a Nd1.85Ce0.15CuO4 single crystal (Tc =23 K) has been measured by C. C. Homes (Simon Fraser) et al. The authors find small values for the coherence length (xi_0 ~~ 70 Angstroms) and penetration depth (lambda_[ab] = 1600+-100 Angstroms). Since the electron-phonon coupling parameter obtained from normal-state transport measurements obeys lambda_[tr] < 0.5 and there are no Holstein sidebands below Tc, the evidence here indicates that the carriers participating in superconductivity are weakly coupled to the phonons. The authors thus suggest that superconductivity in this material is not due to the electron-phonon mechanism and that it is different from that in the hole-doped superconducting cuprates.

The paramagnetic Meissner effect has been observed by G. S. Okram (NRIM) et al. in Nd2-xCexCuO4 at 40 G. The authors attribute this effect to local oxygen variation, which causes nonsuperconducting or lower-Tc regions imbedded inside the higher-Tc regions of the sample.

Borocarbides

The synthesis of thin films of RN2B2C (R = Y, Er) by planar magnetron sputtering and their investigation by STM are reported by A. Andreone (Napoli) et al. The STM results, together with dc transport measurements, give strong evidence for the weak-coupling BCS nature of these compounds. Further details are presented in a related paper by M. Iavarone et al. (Napoli).

Thin Films

The low-temperature capability of a scanning-tip microwave near-field microscope to study superconductors has been explored by I. Takeuchi (Lawrence Berkeley) et al. The shift in the quality factor Q of the microscope resonator can be used to obtain the temperature dependence of the surface resistance of a local region under the tip. The authors scanned patterned YBa2Cu3O7-d films at various temperatures and mapped the surface resistance with high spatial resolution at 1.2 GHz. Edge-region defects in wet-etched patterns were observed and found to be nonsuperconducting at microwave frequencies at 80 K.

Measurements of the field-dependent surface resistance of unpatterned YBa2Cu3O7-d and Tl2Ba2CaCu2O8+d (Tl-2212) films are reported by T. Kaiser et al. (Wuppertal). The authors also report spatially resolved microwave thermometry of resonators at 2 GHz and 77 K. Indications that the films were limited in their performance by magnetic fields were found only for the best films; the performance of lower-quality films was limited by thermal effects.

A sol-gel technique has been used by S. Fujihara (Keio University) et al. to prepare Sr2CuO2F2+d superconductors with Tc = 45-47 K.

A preprint by A. Wong et al. (UBC) reports the growth of YBa2Cu3O7 thin films on SrTiO3 substrates using a scanning pulsed laser deposition system. The laser beam was scanned over the target in order to obtain a reproducible method of composition control at the substrate.

Using focused ion-beam writing with 200 keV Si ions, M. W. Denhoff et al. (NRC-Ottawa) have made weak links consisting of lines written across narrow (10 micrometers) thin-film (150 nm) YBa2Cu3O7 strips. Measurements of the resistance versus temperature revealed a small transition due to the ion-damaged region with a reduced Tc and a resistance value close to that expected for a 200 nm wide stripe of damaged YBCO. A SQUID structure showed only irregular modulation due to an applied magnetic field. The authors conclude that while focused ion-beam writing is an effective way of producing a line of weakened superconductivity, the width of the damaged track may be too large to show strong Josephson effects.

Applications

Two preprints by N. Tralshawala et al. (TCSUH) report on the development of a scanning eddy-current imaging system designed to detect deep subsurface flaws in conducting materials. The device makes use of a YBCO bicrystal SQUID magnetometer, combined with a small cylindrical BSCCO superconducting magnetic shield and a mu-metal shield, so that the instrument can be scanned in a magnetically noisy environment. The instrument has successfully detected cracks and pits through ten layers of aluminum with a total thickness of 5 cm at room temperature.

Progress toward the development of three-terminal HTS (YBCO) quasiparticle-injection devices is reported by C. W. Schneider (Karlsruhe) et al. The observed current gain for a YBCO device with a natural barrier and a normal-conducting counter electrode was 6.2 at 40 K. The main obstacle to achieving higher current gain is the unsolved problem of finding a suitable barrier that allows for quasiparticle tunneling.

The design, simulation, fabrication, and testing of a compact one-pole filter at 2 GHz for the transmit stage of mobile telecommunications base stations are reported by M. A. Hein (Wuppertal) et al. Values of the unloaded quality factor Q_0 up to 10^6 were achieved with double-sided 2"-diameter YBCO films on LaAlO3 substrates.

Preprints by P. Schaetzle et al. (Dresden) and by G. Fuchs et al. (Dresden) report on the fabrication of single-grain YBCO monoliths, obtained by a melt crystallization process upon seeding with oriented SmBa2Cu3O7-d seed crystals. The authors report that the resulting samples could be used as trapped-field magnets; the maximum trapped field was about 1 T at 77 K, but this increased to 9 T at 47 K. The trapped field below 50 K was found to be limited by the mechanical strength of the samples, for which a value of 25 MPa was estimated.

YBCO superconducting magnetic bearings have been tested in a high-speed motor at 77 K by P. Stoye (Dresden) et al. The shaft of an asynchronous motor was stabilized by two superconducting magnetic bearings. Each bearing was made of two concentric NdFeB ring magnets fixed to the shaft, supported between two YBCO rings, 70 mm in diameter. The YBCO rings consisted of six segments of melt-textured material. At atmospheric pressure the shaft was safely rotated at speeds up to 12,000 rpm, and in experiments in a reduced gas pressure of 1.5 mbar a stable rotation speed of 42,000 rpm was achieved.

The status of the production of Bi-2223 tapes for power applications is discussed in a preprint by P. Vase (Nordic Superconductor Technologies) et al. The authors discuss mechanical properties and deformation problems, review the powder-in-tube technique, present projections for the global market development for superconducting tapes, and give various scenarios for bringing production costs down to competitive levels.

A preprint by P. Verges et al. (Dresden) reports on the performance of small double-pancake coils with a 15 mm bore fabricated from Ag-sheathed multifilamentary Bi-2223 tapes with the wind-and-react technique. In a double-pancake coil with a total tape length of 48 m, a magnetic field of 1 T could be generated at 20 K.

Theory

A two-dimensional system of fermions with an indirect Einstein phonon-exchange attraction and a local four-fermion interaction has been considered by V. M. Loktev and V. M. Turkowski (Kyiv). The authors find that in such a system with attraction between particles, a nonsuperconducting pseudogap phase arises in addition to the normal and superconducting phases. In the pseudogap phase, the absolute value of the order parameter is finite, but its phase is random.

Transverse spin fluctuations in the stripe phase of cuprate superconductors have been calculated by C.N.A. van Duin and J. Zaanen (Leiden). The authors conclude that spin fluctuations are responsible for preventing the ordering of spins at the charge-ordering temperature, despite a possible dominance of charge-spin coupling in the longitudinal channel.

The properties of a charged Bose liquid immersed in a uniform background charge at zero temperature have been studied by K. Lee and O. Tchernyshyov (Columbia). The authors find that oscillatory shielding of external localized electric charge, rotons, and charge-density waves (charge stripes in two dimensions) occur in any dimensions. The authors relate their work to the charge stripes recently observed in cuprates and nickelates.

A preprint by E. Otnes and A. Sudbo (Trondheim) reports an analysis of the Cooper problem using a lattice model including on-site and near-neighbor interactions. The authors find a change of symmetry upon doping, from s-wave at low filling fractions to d_[x^2-y^2] at higher filling fractions. The authors also calculate the critical temperature Tc and various thermodynamic quantities (free energy, entropy, specific heat, and critical magnetic fields).

Two preprints by R. Kouba and C. Ambrosch-Draxl (Graz) report first-principles frozen-phonon LAPW calculations for the determination of the force-free geometry and the dynamical matrix of the five Raman-active A_[1g] modes in YBa2Cu3O7. Two different schemes were used to treat electronic exchange and correlation effects. With the local density approximation (LDA), the phonon frequencies showed a deviation from experimental values of about -10%. With a generalized gradient approximation (GGA), however, the frequency values were significantly improved and the eigenvectors agreed well with experiment. Further details are provided in a preprint by C. Ambrosch-Draxl et al.

According to a preprint by E. A. Pashitskii (Kiev and Wisconsin) et al., the zero-bias conductance peak often observed in tunnel and point junctions of cuprate superconductors can be a consequence of d-wave symmetry of the order parameter, combined with strong unitary elastic scattering of the current carriers by nonmagnetic impurities in the vicinity of the junction interface.

A method to solve the Bogoliubov-de Gennes equation for superconductors self-consistently, using the recursion method, has been developed by A. M. Martin and J. F. Annett (Bristol). The authors find that the density of states at an SN or SS interface has a complex structure, including the effects of normal surface Friedel oscillations, a spatially varying gap, Andreev states within the gap, and subtle effects associated with the interplay of the gap and the normal Van Hove peaks in the density of states. In the case of bulk d-wave superconductors, the surface leads to mixing of different order-parameter symmetries near the interface and substantial local filling in of the gap.

Using a two-gap model, S. D. Adrian (NRL) et al. have calculated the superconducting density of states for the cuprates, especially YBa2Cu3O7, including its dependence on temperature and oxygen content. The authors note that magnetic scattering in the second band, which is closely related to the oxygen content, can explain the gapless behavior observed in the oxide superconductors.

The BCS theory has been used by M.-A. Park (Seoul National) et al. to calculate the influence of both nonmagnetic and magnetic impurities on the transition temperature of a d-wave superconductor. In both cases, as a function of the scattering rate, Tc initially decreases linearly, and Tc drops abruptly to zero at a critical impurity concentration. Nonmagnetic and magnetic impurities depress Tc almost equally.

A preprint by A. Bill (Lawrence Berkeley) et al. shows that various factors can lead to an isotopic dependence of the penetration depth lambda. Nonadiabaticity (Jahn-Teller crossing) leads to an isotope effect of the charge-carrier concentration n and consequently of lambda in doped superconductors such as the cuprates. The authors show that the presence of magnetic impurities or a proximity contact also can lead to an isotopic dependence of lambda, and in this case the isotope coefficient beta = - dln[lambda]/dlnM is temperature dependent. The authors suggest a number of experiments to test the theory.

A multiband model for high-Tc superconductors is proposed by R. Combescot (ENS-Paris). The author applies the theory to Bi-2212 and finds that nodes of the order parameter are not located at the 45-degree direction, making an experimental determination of the node locations an important test of the model.

The crossover temperature between the mean-field and the full-critical regions for thermal fluctuations around the superconducting transition has been calculated by M. V. Ramallo and F. Vidal (Santiago de Compostela) for single-layered and bilayered superconductors at zero applied magnetic field.

The effect of a random superconducting order parameter on the localization of quasiparticles has been studied by D. E. Katsanos (Ioannina) et al. using numerical finite-size scaling of the Bogoliubov-de Gennes tight-binding Hamiltonian. The authors obtain Anderson localization in two dimensions and a mobility edge where the states localize in three dimensions.

Calculations of the binding energies of peroxy (O2^[2-]) bipolarons in La2CuO4 have been carried out by C.R.A. Catlow (Royal Institution of Great Britain) et al. The results suggest that peroxy-like bipolarons are stable species in cuprate conductors and that stabilizing lattice relaxations will not prevent them from acting as charge carriers.

Other Activities

Magnetic relaxation measurements of flux creep in the cubic superconductor Ba1-xKxBiO3 (Tc ~~ 30 K) are reported by T. Klein et al. (Grenoble). The authors find that the relaxation rate increases sharply as the vortex-glass transition at T_g is approached. The behavior is attributed to an anomalous increase of the mu exponent [U(J) = U_0(J_0/J)^[mu]] near T_g(H).

Overviews

A book chapter by W. Wong-Ng (NIST-Gaithersburg) reviews studies of the structures of the Bi-containing binary, ternary, and quaternary compounds in the Bi-Sr-Ca-Cu-O system. The occurrence of the incommensurate lattice in the high-Tc phases is also summarized. The variation of the oxidation state and the Bi lone-pair electrons play important roles in determining the stereochemistry of these compounds. This article will be of special interest to those involved in the processing of the Bi cuprate materials (134 refs.).

A brief overview of the progress, properties, and prospects of passive high-temperature superconducting microwave devices in Europe has been prepared by M. A. Hein (Wuppertal). After a brief discussion of materials and their microwave characterization, the author discusses a few HTS microwave devices (N-pole filters, multiplexers, high-Q resonators, and HTS receive coils for NMR and magnetic resonance imaging). The author concludes by discussing a number of remaining challenges (29 refs.).

Ph.D. Thesis

Planar single-layer high-Tc SQUID gradiometers were developed and optimized in the course of the Ph.D. thesis research of L. Doerrer (Jena). The author reports the achievement of gradient sensitivities comparable with the best international results. Three different types of Josephson junctions were used: bicrystal junctions, step-edge junctions, and ion-beam-modified microbridges. Possible applications and suggestions for enhancing the gradient sensitivity and reducing the imbalance are discussed in the thesis (256 refs.). Contributed by John R. Clem

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

S. D. Adrian, S. A. Wolf, O. Dolgov, S. Shulga, and V. Z. Kresin, "Density of States and the Energy Gap in Superconducting Cuprates." To be published in Phys. Rev. B. Naval Research Laboratory, Washington, DC 20375-5000.

I. N. Afanas'eva, G. M. Kuz'micheva, V. V. Luparev, and E. P. Khlybov, "The Perovskite-Like Cuprates on the Indium Basis." To be published in Zh. Neorgan. Khimii. Contact G. M. Kuz'micheva, Department of Solid State Physics and Chemistry, State Lomonosov Academy of Fine Chemical Technology, 86 pr. Vernadsky, Moscow 117571, RUSSIA; telephone +7 095 248 07 62; e-mail kuz7micheva@glasnet.ru or alekz@cs.msu.su.

M. Aleksa, P. Pongratz, O. Eibl, F. M. Sauerzopf, H. W. Weber, T. W. Li, and P. H. Kes, "TEM Observation of Neutron-Induced Collision Cascades in Bi-2212 Single Crystals." Submitted to Physica C. Contact H. W. Weber, Atominstitut der OEsterreichischen Universitaeten, A-1020 Wien, AUSTRIA; e-mail weber@ati.ac.at.

Claudia Ambrosch-Draxl, Robert Kouba, and Peter Knoll, "First-Principles Band-Structure Calculations as a Tool for the Quantitative Interpretation of Raman Spectra of High Temperature Superconductors." To be published in Z. Phys. B. Institut fuer Theoretische Physik, Universitaet Graz, Universitaetsplatz 5, A-8010 Graz, AUSTRIA; telephone +43 316 380 5235; telefax +43 316 380 9820; e-mail cad@cleopatra.kfunigraz.ac.at; Web site http://physik.kfunigraz.ac.at/~cad. 74.25.Kc; 33.20.Fb; 31.15.Ew.

A. Andreone, C. Aruta, M. L. Russo, R. Vaglio, G. W. Crabtree, Y. De Wilde, M. Iavarone, and P. C. Canfield, "Synthesis and STM Investigation of Rare-Earth Superconducting Borocarbides." Submitted to Supercond. Sci. Technol. Istituto Nazionale per la Fisica della Materia (INFM), Dipartimento di Scienze Fisiche, Universita di Napoli "Federico II," Piazzale Tecchio 80, I-80125 Napoli, ITALY; telephone +39 81 768 2423; telefax +39 81 239 1821; e-mail andreone@na.infn.it.

F. Bass, B. Ya. Shapiro, and M. Shvartser, "Corrugation Flux Front Instability in Type-II Superconductors." Contact B. Ya. Shapiro, Department of Physics, Institute of Superconductivity, Bar-Ilan University, Ramat Gan 52900, ISRAEL; telephone +972 3 5318980; telefax +972 3 5353298; e-mail shapiro@physnet.ph.biu.ac.il. 74.60.Ge.

F. Bass, B. Ya. Shapiro, and M. Shvartser, "Dynamical Instability of Flux Front in Type-II Superconductors." To be published in Europhys. Lett. Contact B. Ya. Shapiro, Department of Physics, Institute of Superconductivity, Bar-Ilan University, Ramat Gan 52900, ISRAEL; telephone +972 3 5318980; telefax +972 3 5353298; e-mail shapiro@physnet.ph.biu.ac.il. 74.60.Ge.

F. Bass, B. Ya. Shapiro, and M. Shvartser, "Nonlinear Flux Diffusion in Type-II Superconductors." Submitted to Physica C. Contact B. Ya. Shapiro, Department of Physics, Institute of Superconductivity, Bar-Ilan University, Ramat Gan 52900, ISRAEL; telephone +972 3 5318980; telefax +972 3 5353298; e-mail shapiro@physnet.ph.biu.ac.il. Key words: superconductivity, flux motion. 74.60.Ge.

A. Bill, V. Z. Kresin, and S. A. Wolf, "Isotope Effect of the Penetration Depth in Superconductors." Lawrence Berkeley Laboratory, University of California, 1 Cyclotron Road, Berkeley, CA 94720.

Gilson Carneiro, "Equilibrium Vortex-Line Configurations and Critical Currents in Thin Films Under a Parallel Field." Submitted to Phys. Rev. B. Instituto de Fisica, Universidade Federal do Rio de Janeiro, C.P. 68528, 21945-970 Rio de Janeiro, RJ, BRAZIL; e-mail gmc@if.ufrj.br; preprint also available at cond-mat@xxx.lanl.gov (#9707248). 74.76.-w; 74.60.-w.

C.R.A. Catlow, M. S. Islam, and X. Zhang, "The Structure and Energies of Peroxy Bipolarons in La2CuO4." To be published in J. Phys. Cond. Mat. Davy Faraday Research Laboratory, Royal Institution of Great Britain, 21 Albemarle Street, London W1X 4BS, UNITED KINGDOM; M. S. Islam's telephone at University of Surrey +44 1483 300800, ext. 2596; telefax +44 1483 300803; e-mail m.islam@surrey.ac.uk.

L. Colonescu, J. Berthon, and R. Suryanarayanan, "Insulator-Superconductor Transition in Tm0.4Pr0.6Ba2Cu3O7 by Iso-Valent Substitution at Ba Site." To be published in Solid State Commun. Contact R. Suryanarayanan, Laboratoire de Chimie des Solides, URA CNRS 446, Universite de Paris-Sud, Batiment 414, F-91405 Orsay Cedex, FRANCE; telephone +33 1 69 15-6107 or -7018; telefax +33 1 69 15-4797; e-mail suryan@isma.isma.u-psud.fr.

R. Combescot, "Multiband Model of High-Tc Superconductors." Laboratoire de Physique Statistique, Ecole Normale Superieure, 24 rue Lhomond, F-75231 Paris Cedex 05, FRANCE; e-mail roland.combescot@lps.ens.fr; preprint also available at cond-mat@xxx.lanl.gov (#9707241). 74.20.Fg; 74.72.Bk; 74.25.Jb.

Lawrence P. Cook and Winnie Wong-Ng, "Primary Crystallization Volume of BCSSO 2212: Applications to Crystal Growth and Melt Processing." Submitted to Impact of Recent Adv. in Syn. and Proc. of Ceram. Supercond.: Proc. of the 99th Annual Mtg. of the Amer. Ceram. Soc., Cincinnati, Ohio, May 5-7, 1997. Ceramics Division, National Institute of Standards and Technology, Gaithersburg, MD 20899; Winnie Wong-Ng's telephone (301) 975-5791; telefax (301) 990-8729; e-mail wongng@tiber.nist.gov.

D. E. Daney, H. J. Boenig, M. P. Maley, J. Y. Coulter, and S. Fleshler, "Single and Three-Phase ac Losses in HTS Superconducting Power Transmission Line Prototype Cables." To be published in Adv. Cryogenics Eng.: Proc. of the Int. Cryogenic Eng. Conf. and the Int. Cryogenic Mater. Conf. (Joint ICMC-CEC 1997 Conf.), Portland, Oreg., July 27-Aug. 1, 1997. Los Alamos National Laboratory, Mail Stop J576, Los Alamos, NM 87545; telephone (505) 665-0216; telefax (505) 665-7740; e-mail daney@esa.lanl.gov.

K. Deligiannis, P.A.J. de Groot, M. Oussena, S. Pinfold, R. Langan, R. Gagnon, and L. Taillefer, "New Features in the Vortex Phase Diagram of YBa2Cu3O7-d." To be published in Phys. Rev. Lett. Department of Physics, University of Southampton, Southampton S017 1BJ, UNITED KINGDOM; telephone +44 1703 595000; telefax +44 1703 593910. 74.60.Ge.

Mike W. Denhoff, Mae Gao, L. E. Erickson, and G. Champion, "Weak Links Produced in YBCO Thin Films Using a Focused Ion Beam." To be published in the Proc. of the 3rd European Conf. on Appl. Supercond. (EUCAS'97), Veldhoven, The Netherlands, June 30-July 3, 1997. Institute for Microstructural Sciences, National Research Council, 1500 Montreal Road, Bldg. M-36, Ottawa, ON, CANADA K1A 0R6; e-mail mike.denhoff@nrc.ca.

Y. De Wilde, N. Miyakawa, P. Guptasarma, M. Iavarone, L. Ozyuzer, J. F. Zasadzinski, P. Romano, D. G. Hinks, C. Kendziora, G. W. Crabtree, and K. E. Gray, "Unusual Strong-Coupling Effects in the Tunneling Spectroscopy of Optimally-Doped and Overdoped 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.

Lars Doerrer, "Planar Thin Film SQUID Gradiometers Based on High Temperature Superconductors." Submitted as a Ph.D. thesis (Friedrich-Schiller-Universitaet Jena). Institut fuer Festkoerperphysik, Freidrich-Schiller-Universitaet Jena, Max-Wien-Platz 1, D-07743 Jena, GERMANY.

G. Fuchs, S. Gruss, G. Krabbes, P. Schaetzle, K. H. Mueller, J. Fink, and L. Schultz, "Trapped Field Magnets from Melt Textured YBCO Samples." Presented at the 3rd European Conf. on Appl. Supercond. (EUCAS'97), Veldhoven, The Netherlands, June 30-July 3, 1997. Institut fuer Festkoerper- und Werkstofforschung Dresden, P.O. Box 270016, D-01171 Dresden, GERMANY.

S. Fujihara, Y. Masuda, J.-S. Jin, T. Kimura, and K. Tanabe, "An Interesting Sol-Gel Route to Prepare Oxyfluoride Sr2CuO2F2+d Superconductors." Department of Applied Chemistry, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223, JAPAN; telefax +81 45 562 7625. Key words: oxyfluoride superconductor, Sr2CuO2F2+d, Sr2CuO3, sol-gel, magnetization.

Alexandr Yu. Galkin, Milos Jirsa, Ladislav Pust, Petr Nalevka, Michael R. Koblischka, Vladimir M. Pan, and Rene Fluekiger, "Low Field Relaxation Measurements of Induced Magnetic Moment in Bi(2223)/Ag Tape and Bi(2212) Single Crystal." Presented at the 3rd European Conf. on Appl. Supercond. (EUCAS'97), Veldhoven, The Netherlands, June 30-July 3, 1997. Institute of Physics, AV CR, Na Slovance 2, CZ-180 40 Praha 8, CZECH REPUBLIC.

J. Gerster, G. Kaiser, L. Reissig, M. Thuerk, and P. Seidel, "Low Noise Cold Head of a Four-Valve Pulse Tube Refrigerator." To be published in Adv. Cryogenics Eng.: Proc. of the Int. Cryogenic Eng. Conf. and the Int. Cryogenic Mater. Conf. (Joint ICMC-CEC 1997 Conf.), Portland, Oreg., July 27-Aug. 1, 1997. Institut fuer Festkoerperphysik, Friedrich-Schiller-Universitaet Jena, Lessingstrasse 8, D-07743 Jena, GERMANY; P. Seidel's telephone +49 3641-635685 or -635681; telefax +49 3641-635681; e-mail seidel@ifk.uni-jena.de.

T. J. Hagenaars and E. H. Brandt, "Monte-Carlo Calculation of Longitudinal and Transverse Resistivities in a Model Type-II Superconductor." Center for the Epidemiology of Infectious Disease, Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3PS, UNITED KINGDOM; preprint also available at cond-mat@xxx.lanl.gov (#9707214). 74.60.-w; 74.60.Ge.

M. A. Hein, "Progress, Properties and Prospects of Passive High-Temperature Superconductive Microwave Devices in Europe." To be published in Appl. Supercond.: Proc. of the 3rd European Conf. on Appl. Supercond. (EUCAS'97), Veldhoven, The Netherlands, June 30-July 3, 1997. Fachbereich Physik, Universitaet-GH Wuppertal, Gauss-Strasse 20, D-42097 Wuppertal, GERMANY.

M. A. Hein, B. A. Aminov, A. Baumfalk, H. J. Chaloupka, F. Hill, T. Kaiser, S. Kolesov, G. Mueller, and H. Piel, "High-Power High-Q YBaCuO Disk Resonator Filter." To be published in Appl. Supercond.: Proc. of the 3rd European Conf. on Appl. Supercond. (EUCAS'97), Veldhoven, The Netherlands, June 30-July 3, 1997. Fachbereich Physik, Universitaet-GH Wuppertal, Gauss-Strasse 20, D-42097 Wuppertal, GERMANY; T. Kaiser's telephone +49 202 439 2860; telefax +49 202 439 2811; e-mail kaiser@wpos4.physik.uni-wuppertal.de.

C. C. Homes, B. P. Clayman, J. L. Peng, and R. L. Greene, "Optical Properties of Nd1.85Ce0.15CuO4." To be published in Phys. Rev. B. Department of Physics, Brookhaven National Laboratory, Building 510B, P.O. Box 5000, Upton, NY 11973-5000; telephone (516) 344-7579; telefax (516) 344-2739; e-mail homes@bnl.gov. 74.25.Gz; 74.25.Kc; 74.72.Jt.

M. Iavarone, A. Andreone, C. Aruta, A. Cassinese, F. Fontana, F. Palomba, M. L. Russo, and R. Vaglio, "Growth and Characterization of Re-Ni2B2C Superconducting Thin Films." Submitted to the Proc. of the 3rd European Conf. on Appl. Supercond. (EUCAS'97), Veldhoven, The Netherlands, June 30-July 3, 1997. Istituto Nazionale di Fisica della Materia (INFM), Dipartimento di Scienze Fisiche, Universita di Napoli "Federico II," Piazzale Tecchio 80, I-80125 Napoli, ITALY; A. Andreone's telephone +39 81 768 2423; telefax +39 81 239 1821; e-mail andreone@na.infn.it.

Takekazu Ishida, Kiichi Okuda, Hidehito Asaoka, Yukio Kazumata, Kenji Noda, and Humihiko Takai, "Two- and Four-Fold ab-Plane Torque Symmetry in Untwinned YBa2Cu3O7 Single Crystals." To be published in Phys. Rev. B. Department of Physics and Electronics, Osaka Prefecture University, Sakai, Osaka 593; JAPAN; e-mail ishida@center.osakafu-u.ac.jp. 74.72.Bk.

M. Jirsa and L. Pust, "A Comparative Study of Irreversible Magnetization and Pinning Force Density in (RE)Ba2Cu3O7-d and Some Other High-Tc Compounds in View of a Novel Scaling Scheme." To be published in Physica C. Institute of Physics, Academy of Sciences of the Czech Republic, Na Slovance 2, CZ-18040 Praha 8, CZECH REPUBLIC. 74.60.Jg; 74.60.Ge.

T. Kaiser, C. Bauer, W. Diete, M. A. Hein, J. Kallscheuer, G. Mueller, and H. Piel, "Thermal and Magnetic Limitations of the Linear Surface Resistance of Epitaxial HTS Films in High Microwave Fields." To be published in Appl. Supercond.: Proc. of the 3rd European Conf. on Appl. Supercond. (EUCAS'97), Veldhoven, The Netherlands, June 30-July 3, 1997. Fachbereich Physik, Universitaet-GH Wuppertal, Gauss-Strasse 20, D-42097 Wuppertal, GERMANY; telephone +49 202 439 2860; telefax +49 202 439 2811; e-mail kaiser@wpos4.physik.uni-wuppertal.de.

E. Kaldis, J. Roehler, E. Liarokapis, N. Poulakis, K. Conder, and P. W. Loeffen, "A Displacive Structural Transformation in the CuO2 Planes of YBa2Cu3Ox at the Underdoped-Overdoped Phase Separation Line." Contact J. Roehler, II. Physikalisches Institute, Universitaet zu Koeln, Zuelpicherstr. 77, D-50937 Koeln, GERMANY; e-mail abb12@rs1.rrz.uni-koeln.de; preprint also available at cond-mat@xxx.lanl.gov (#9707196).

D. E. Katsanos, S. N. Evangelou, and C. J. Lambert, "Superconductivity-Induced Anderson Localization." Department of Physics, University of Ioannina, Ioannina 45 110, GREECE; e-mail dkatsan@cc.uoi.gr; preprint also available at cond-mat@xxx.lanl.gov (#9707150). 72.10.Bg; 73.40.Gk; 74.50.+r.

Beom Jun Kim, M. Y. Choi, S. Ryu, and D. Stroud, "Anomalous Relaxation in the XY Gauge Glass." To be published in Phys. Rev. B. Department of Physics and Center for Theoretical Physics, Seoul National University, Seoul 151-742, KOREA; e-mail bjkim@phya.snu.ac.kr; preprint also available at cond-mat@xxx.lanl.gov (#9707140). 75.10.Nr; 74.50.+r; 74.60.Ge; 61.20.Lc.

T. Klein, W. Harneit, L. Baril, C. Escribe-Filippini, and D. Feinberg, "Comment on 'Plastic Vortex Creep in YBa2Cu3O7-x Crystals.'" To be published in Phys. Rev. Lett. Laboratoire d'Etudes des Proprietes Electroniques des Solides, Centre National de la Recherche Scientifique, B.P. 166, F-38042 Grenoble Cedex 9, FRANCE; telephone +33 4 7688 1008; telefax +33 4 7688 7988; e-mail klein@lepes.polycnrs-gr.fr. 74.60.Ge; 74.72.Bk.

T. Klein, W. Harneit, I. Joumard, J. Marcus, C. Escribe-Filippini, and D. Feinberg, "Relaxation and Anomalous T and H Dependence of the mu Coefficient in (K,Ba)BiO3 Superconductors." Submitted to Europhys. Lett. Laboratoire d'Etudes des Proprietes Electroniques des Solides, Centre National de la Recherche Scientifique, B.P. 166, F-38042 Grenoble Cedex 9, FRANCE; telephone +33 4 7688 1008; telefax +33 4 7688 7988; e-mail klein@lepes.polycnrs-gr.fr. 74.60.Ge; 74.25.Ha.

V. N. Kokunova, G. M. Kuz'micheva, S. I. Novikova, and A. V. Mitin, "The Search of the New Ruthenium-Based Superconducting Phases with the Perovskite-Like Structures." To be published in Zh. Neorgan. Khimii. Contact G. M. Kuz'micheva, Department of Solid State Physics and Chemistry, State Lomonosov Academy of Fine Chemical Technology, 86 pr. Vernadsky, Moscow 117571, RUSSIA; telephone +7 095 248 07 62; e-mail kuz7micheva@glasnet.ru or alekz@cs.msu.su.

Robert Kouba and Claudia Ambrosch-Draxl, "Investigation of A1g Phonons in YBa2Cu3O7 by Means of LAPW Atomic-Force Calculations." Institut fuer Theoretische Physik, Universitaet Graz, Universitaetsplatz 5, A-8010 Graz, AUSTRIA; Claudia Ambrosch-Draxl's telephone +43 316 380 5235; telefax +43 316 380 9820; e-mail cad@cleopatra.kfunigraz.ac.at; Web site http://physik.kfunigraz.ac.at/~cad; preprint also available at cond-mat@xxx.lanl.gov (#9707124).

Robert Kouba and Claudia Ambrosch-Draxl, "Volume Dependence of the A1g Phonons in YBa2Cu3O7." To be published in Z. Phys. B. Institut fuer Theoretische Physik, Universitaet Graz, Universitaetsplatz 5, A-8010 Graz, AUSTRIA; Claudia Ambrosch-Draxl's telephone +43 316 380 5235; telefax +43 316 380 9820; e-mail cad@cleopatra.kfunigraz.ac.at; Web site http://physik.kfunigraz.ac.at/~cad. 74.25.Kc; 31.15.Ew.

Kimyeong Lee and Oleg Tchernyshyov, "Novel Phenomena in Charged Bose Liquid." Preprint #CU-TP-84. Department of Physics, Columbia University, New York, NY 10027; e-mail klee@cuphyh.phys.columbia.edu; preprint also available at cond-mat@xxx.lanl.gov (#9707202). 74.20.Mn; 71.35.Lk; 11.15.Ex.

LI Rukang, "Pb2BaCuFeO5X(X=Cl,Br), New Intergrowth Compounds Composed by CsCl Type and Bi-Pyramidal Defective Perovskite Blocks." Department of Chemistry, University of Science and Technology of China, Hefei, Anhui 230026, PEOPLE'S REPUBLIC OF CHINA; e-mail ruli@chemix.mpi-stuttgart.mpg.de.

Y. P. Li, J. R. Liu, X. T. Cui, Z. J. Qu, and W. K. Chu, "RBS and Ion Channeling Studies of Ag-Doped YBa2Cu3O7-d Targets and Films." Preprint #97:081; submitted to the Proc. of the 13th Int. Conf. on Ion Beam Analysis, Lisbon, Portugal, July 27-Aug. 1, 1997; to be published in Nuclear Instruments and Methods in Phys. Res. B. Texas Center for Superconductivity, University of Houston, Houston, TX 77204-5932; telephone (713) 743-8258; telefax (713) 743-8201; e-mail ypli@uh.edu. Key words: Ag-doped YBa2Cu3O7-d films, RBS, ion channeling. 74.76.Bz; 68.55.Ln; 82.80.Yc.

V. M. Loktev and V. M. Turkowski, "On the Theory of the Pseudogap Formation in 2D Attracting Fermion Systems." Bogolyubov Institute for Theoretical Physics, Metrologichna Str. 14-b, Kyiv 252143, UKRAINE; e-mail vloktev@gluk.apc.org; preprint also available at cond-mat@xxx.lanl.gov (#9707191). Key words: 2D metal, arbitrary carrier density, normal phase, abnormal normal phase, pseudogap, superconducting phase, Berezinskii-Kosterlitz-Thouless phase, electron-electron and electron-hole pairing. 67.20.+k; 74.20.-z; 74.25.-q; 74.72.-h.

V. V. Luparev and G. M. Kuz'micheva, "The Crystal Structure of the (Hg,Ce,Cu)(Sr,Ho)2(Ho,Sr)Cu2O6+d Phases." To be published in Zh. Neorgan. Khimii. Contact G. M. Kuz'micheva, Department of Solid State Physics and Chemistry, State Lomonosov Academy of Fine Chemical Technology, 86 pr. Vernadsky, Moscow 117571, RUSSIA; telephone +7 095 248 07 62; e-mail kuz7micheva@glasnet.ru or alekz@cs.msu.su.

V. V. Luparev, G. M. Kuz'micheva, and E. P. Khlybov, "Connection Between (Sr1-yNdy)CuO2-d Phase Composition and Tc." To be published in Zh. Neorgan. Khimii. Contact G. M. Kuz'micheva, Department of Solid State Physics and Chemistry, State Lomonosov Academy of Fine Chemical Technology, 86 pr. Vernadsky, Moscow 117571, RUSSIA; telephone +7 095 248 07 62; e-mail kuz7micheva@glasnet.ru or alekz@cs.msu.su.

Yu. G. Makhlin, "Spectral Flow in Vortex Dynamics of d-Wave Superconductors." Submitted to Phys. Rev. B. Department of Physics, University of Illinois at Urbana-Champaign, 1110 West Green Street, Urbana, IL 61801; e-mail makhlin@london.physics.uiuc.edu; preprint also available at cond-mat@xxx.lanl.gov (#9707038).

A. M. Martin and J. F. Annett, "Self-Consistent Interface Properties of d and s-Wave Superconductors." H. H. Wills Physics Laboratory, University of Bristol, Royal Fort, Tyndall Avenue, Bristol BS8 1TL, UNITED KINGDOM; e-mail a.martin@bristol.ac.uk; preprint also available at cond-mat@xxx.lanl.gov (#9708086). 74.80.Fp; 74.80.-g.

J. I. Martin, M. Velez, J. Nogues, and Ivan K. Schuller, "Flux Pinning in a Superconductor by an Array of Submicrometer Magnetic Dots." Contact Ivan K. Schuller, Department of Physics 0350, University of California, 9500 Gilman Drive, La Jolla, CA 92093-0350; e-mail ischuller@ucsd.edu.

V. Martisovits and D. L. Cox, "Staggered Pairing Phenomenology for UPd2Al3 and UNi2Al3." Department of Physics, Ohio State University, Columbus, OH 43210; e-mail martisov@pacific.mps.ohio-state.edu; preprint also available at cond-mat@xxx.lanl.gov (#9706245).

O. V. Misochko and Gu Genda, "Study of Electronic Raman Continua in Single Crystal Bi2Sr2CaCu2O8+x." To be published in Physica C. Institute of Solid State Physics, Russian Academy of Sciences, 142432 Chernogolovka, Moscow Region, RUSSIA; e-mail misochko@issp.ac.ru. Key words: Raman scattering, superconducting gap, high-Tc superconductors. 74.25.Gz; 78.30.-j; 74.72.Hs.

M. A. Moore, T. J. Newman, A. J. Bray, and S.-K. Chin, "Mixed Phases in U(N) Superconductivity." Theory Group, Department of Physics, University of Manchester, Manchester, M13 9PL, UNITED KINGDOM; e-mail tim@a12.ph.man.ac.uk; preprint also available at cond-mat@xxx.lanl.gov (#9707297). 64.60.Fr; 74.20.De.

Karl-Heinz Mueller, "ac Loss in Y-123/Hastelloy Superconducting Tapes." To be published in the Proc. of the 3rd European Conf. on Appl. Supercond. (EUCAS'97), Veldhoven, The Netherlands, June 30-July 3, 1997. Division of Telecommunications and Industrial Physics, CSIRO, P.O. Box 218, Lindfield, NSW 2070, AUSTRALIA; e-mail karl@dap.csiro.au.

K.-H. Mueller, "Self-Field Hysteresis Loss in Periodically Arranged Superconducting Strips." To be published in Physica C. Division of Telecommunications and Industrial Physics, CSIRO, P.O. Box 218, Lindfield, NSW 2070, AUSTRALIA; e-mail karl@dap.csiro.au. 85.25.Kx; 84.70.+p; 74.76.Bz.

Petr Nalevka, Milos Jirsa, Ladislav Pust, Alexandr Yu. Galkin, Michael R. Koblischka, and Rene Fluekiger, "Detailed Magnetization Study of Inter- and Intragranular Currents in Ag-Sheathed Bi-2223 Tape." Presented at the 3rd European Conf. on Appl. Supercond. (EUCAS'97), Veldhoven, The Netherlands, June 30-July 3, 1997. Institute of Physics, Academy of Sciences of the Czech Republic, Na Slovance 2, CZ-18040 Praha 8, CZECH REPUBLIC.

M. R. Norman, H. Ding, M. Randeria, J. C. Campuzano, T. Yokoya, T. Takeuchi, T. Takahashi, T. Mochiku, K. Kadowaki, P. Guptasarma, and D. G. Hinks, "Gradual Appearance of the Fermi Surface in the Pseudogap State of High-Tc Superconductors." Submitted to Nature. Materials Science Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439; telefax (708) 252-9595; e-mail janice_coble@qmgate.anl.gov.

Gunadhor S. Okram, D. T. Adroja, B. D. Padalia, Om Prakash, and P.A.J. de Groot, "Paramagnetic Meissner Effect in Nd2-xCexCuOy Superconductors at 40G and Flux Trapping." To be published in J. Phys. Cond. Mat. 4G-2SG Tsukuba Magnet Laboratory, National Research Institute for Metals, 3-13 Sakura, Tsukuba-shi, Ibaraki 305, JAPAN; telephone +81 298 59 5092; telefax +81 298 59 5011; e-mail okram@nrim.go.jp.

E. Otnes and A. Sudbo, "Thermodynamics of Superconducting Lattice Fermions." Department of Physics, Norwegian University of Science and Technology, N-7034 Trondheim, NORWAY; e-mail otnes@phys.ntnu.no; A. Sudbo's telephone +47 73 59 3403; telefax +47 73 59 7710; preprint also available at cond-mat@xxx.lanl.gov (#9707225).

Mi-Ae Park, M. H. Lee, and Yong-Jihn Kim, "Impurity Scattering in a d-Wave Superconductor." Submitted to Mod. Phys. Lett. B. Department of Physics, Seoul National University, Seoul 151-742, KOREA; Yong-Jihn Kim's e-mail yjkim@taesan.kaist.ac.kr; Web site http://taesan.kaist.ac.kr/~yjkim; preprint also available at cond-mat@xxx.lanl.gov (#9707235). 74.20.Fg; 74.62.-c; 74.62.Dh.

E. A. Pashitskii, A. E. Pashitskii, and A. B. Nazarenko, "On the Origin of Zero-Bias Conductance Peak in High-Tc Superconductors." Institute of Physics, National Academy of Sciences of Ukraine, Kiev 252650, UKRAINE. 74.80.Fp; 74.62.Dh; 74.50.+r.

M. V. Ramallo and F. Vidal, "On the Width of the Full-Critical Region for Thermal Fluctuations Around the Superconducting Transition in Layered Superconductors." To be published in Europhys. Lett. Laboratorio de Bajas Temperaturas y Superconductividad, Departamento de Fisica de la Materia Condensada, Universidad de Santiago de Compostela, E-15706 Santiago de Compostela, SPAIN. 64.60.-i; 74.40.+k.

E. Sudhakar Reddy and T. Rajasekharan, "Shape Forming Simultaneous with Jc Enhancement in REBa2Cu3O7 Superconductors." To be published in J. Mater. Res. Ceramic Division, Defence Metallurgical Research Laboratory (DMRL), P.O. Kanchanbagh, Hyderabad 500 058, INDIA; e-mail vsbsp@uohyd.ernet.in.

M. Reissner, "Surface Versus Bulk Pinning in a HgBa2Ca2Cu3O8+x Ceramics." To be published in Physica C. Institute of Applied and Technical Physics, Technical University of Vienna, Wiedner Hauptstrasse 8-10/137, A-1040 Wien, AUSTRIA; telephone +43 1 58801 5635; telefax +43 1 586 8814; e-mail reissner@email.tuwien.ac.at. Key words: flux pinning, flux creep, critical current density, collective pinning theory, energy current relation, HgBa2Ca2Cu3O8+x.

A. V. Samoilov, N.-C. Yeh, and C. C. Tsuei, "Electron Localization Effects on the Low-Temperature High-Field Magnetoresistivity of Three-Dimensional Amorphous Superconductors." Submitted to Phys. Rev. B. Department of Physics 114-36, California Institute of Technology, Pasadena, CA 91125.

P. Schaetzle, G. Krabbes, W. Bieger, G. Stoever, G. Fuchs, and S. Gruss, "Improved YBCO Bulk Material for Cryomagnetic 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. Institute of Solid State and Materials Research Dresden, P.O. Box 270016, D-01171 Dresden, GERMANY; G. Krabbes telephone +49 351 2582 395; telefax +49 351 2582 314.

Stefan Scheidl and Valerii M. Vinokur, "Gliding Dislocations in a Driven Vortex Lattice." Submitted to Phys. Rev. B. Institut fuer Theoretische Physik, Universitaet zu Koeln, Zuelpicher Str. 77, D-50937 Koeln, GERMANY; preprint also available from Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439; telefax (708) 252-9595; e-mail janice_coble@qmgate.anl.gov. 74.60.Ge; 61.72.Bb.

C. W. Schneider, R. Schneider, R. Moerman, G. J. Gerritsma, and H. Rogalla, "Recent Progress in Developing HTS Quasi-Particle Injection Devices." To be published in the Proc. of the 3rd European Conf. on Appl. Supercond. (EUCAS'97), Veldhoven, The Netherlands, June 30-July 3, 1997. Forschungszentrum Karlsruhe, Institut fuer Technische Physik, Postfach 3640, D-76021 Karlsruhe, GERMANY; telephone +49 7247 823284; telefax +49 7247 824624; e-mail c.w.schneider@infp.fzk.de.

P. Seidel, M. Grajcar, and A. Plecenik, "Tunneling and Point Contact Spectroscopy of High-Tc Superconducting Thin Films." To be published in Acta Phys. Polonica: Proc. of the 1st Int. Symp. on Scanning Probe Microscopy and Related Methods (SPS'97), Poznan, Poland, July 15-18, 1997. Institut fuer Festkoerperphysik, Friedrich-Schiller-Universitaet Jena, Lessingstrasse 8, D-07743 Jena, GERMANY; telephone +49 3641-635685 or -635681; telefax +49 3641-635681; e-mail seidel@ifk.uni-jena.de.

Sergei Sergeenkov, "Magnetic Field Induced Charging Effects in Josephson Junction Arrays." To be published in J. Phys. I. Instituto de Fisica, Universidade Federal do Rio Grande do Sul, 91501-970 Porto Alegre, BRAZIL; e-mail ssa@if.ufrgs.br. 74.50.+r; 75.80.+q.

U. Staub, L. Soderholm, S. Skanthakumar, R. Osborn, and F. Fauth, "Importance of the Magnetic Ground-State of Pr for Tc Suppression in High-Tc Superconductors." To be published in Europhys. Lett. Swiss Light Source Project, Paul Scherrer Institute, CH-5232 Villigen PSI, SWITZERLAND; telephone +41 56 310 4494; telefax +41 56 310 3151; e-mail urs.staub@psi.ch. 74.62.Dh; 71.70.Ch.

P. Stoye, W. Gawalek, P. Goernert, A. Gladun, and G. Fuchs, "Superconducting Magnetic Bearings in a High Speed Motor." Presented at the 3rd European Conf. on Appl. Supercond. (EUCAS'97), Veldhoven, The Netherlands, June 30-July 3, 1997. Institut fuer Festkoerper- und Werkstofforschung Dresden, D-01171 Dresden, GERMANY.

I. Takeuchi, T. Wei, Fred Duewer, Y. K. Yoo, X.-D. Xiang, V. Talyansky, S. P. Pai, G. J. Chen, and T. Venkatesan, "Low Temperature Scanning-Tip Microwave Near-Field Microscopy of YBa2Cu3O7-x Films." To be published in Appl. Phys. Lett. Contact X.-D. Xiang, Materials Science Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720; e-mail xdxiang@lbl.gov.

A. N. Terentiev, H. G. Lee, M. H. Lee, H. J. Lee, and G. W. Hong, "Measurements of Transport ac Losses in HTS Wires by Vibrating Magnet Technique." Submitted to the Proc. of the 7th Korean Conf. on Mater. and Appl. of Supercond., Yong Pyung, Kangwondo, Korea, Aug. 18-20, 1997. Institute for Chemical Physics, Russian Academy of Sciences, 117977 Moscow, RUSSIA; e-mail terenita@glasnet.ru.

N. Tralshawala, J. R. Claycomb, H. M. Cho, and J. H. Miller, Jr., "Development of Scanning High-Tc SQUID-Based Instrument for Nondestructive Evaluation in a Magnetically Noisy Environment." Preprint #97:087; to be published in Nondestructive Characterization of Materials VIII, edited by R. E. Green, Jr. (Plenum Press, New York). 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.

N. Tralshawala, J. R. Claycomb, and J. H. Miller, Jr., "A Practical SQUID Instrument for Nondestructive Testing." Preprint #97:086; to be published in Appl. Phys. Lett. Texas Center for Superconductivity, University of Houston, Houston, TX 77204-5932; telephone (713) 743-8200; telefax (713) 743-8201; e-mail preprints@www.tcs.uh.edu. 28.41.Qb; 41.20.Gz; 81.70.Dw; 85.25.Dq.

D. P. Tunstall, S. G. Titova, J.T.S. Irvine, and B. J. Mitchell, "Yttrium and Lead NMR Investigation of a 1212 Superconductor Pb(1+x)/2Cu(1-x)/2Sr2Y1-xCaxCu2O7+d." School of Physics and Astronomy, University of St. Andrews, St. Andrews, Fife KY16 9SS, UNITED KINGDOM.

C.N.A. van Duin and J. Zaanen, "Charge- Versus Spin-Driven Stripe Order: The Role of Transversal Spin Fluctuations." Institute Lorentz for Theoretical Physics, Leiden University, P.O.B. 9506, 2300 RA Leiden, THE NETHERLANDS; e-mail cvduin@lorentz.leidenuniv.nl or jan@lorentz.leidenuniv.nl; preprint also available at cond-mat@xxx.lanl.gov (#9707195). 64.60.-i; 71.27.+a; 74.72.-h; 75.10.-b.

Per Vase, Peder Skov-Hansen, Zhenghe Han, Henning Friis Poulson, and Thomas Frello, "Bi-2223 Tapes for Power Applications." Presented at the 3rd European Conf. on Appl. Supercond. (EUCAS'97), Veldhoven, The Netherlands, June 30-July 3, 1997. Nordic Superconductor Technologies, Priorparken 878, DK-2605 Brondby, DENMARK; telephone +45 4348-3592 or -2500; telefax +45 4348-2501; e-mail p.vase@nst.com.

P. Verges, K. Fischer, A. Huetten, T. Staiger, and G. Fuchs, "Fabrication and Properties of Pancake Coils Using Bi-2223/Ag Tapes." Presented at the 3rd European Conf. on Appl. Supercond. (EUCAS'97), Veldhoven, The Netherlands, June 30-July 3, 1997. Institut fuer Festkoerper- und Werkstofforschung Dresden, P.O. Box 270016, D-01171 Dresden, GERMANY; T. Staiger's telephone +49 351 4659-553 or -562; telefax +49 351 4659-537; e-mail t.staiger@ifw-dresden.de.

G. E. Volovik, "Comment on 'Magnus Force in Superfluids and Superconductors.'" Low Temperature Laboratory, Helsinki University of Technology, 02150 Espoo, FINLAND; e-mail volovik@boojum.hut.fi; preprint also available at cond-mat@xxx.lanl.gov (#9707136). 74.50.+r; 74.80.-g.

Andre Wong, Ruixing Liang, Michael Gardner, and Walter N. Hardy, "Reproducible Growth of Highly Crystalline YBa2Cu3O7 Thin Films on SrTiO3 by Scanning Pulsed Laser Deposition." To be published in J. Appl. Phys. Department of Physics and Astronomy, University of British Columbia Vancouver, British Columbia, V6T 1Z1, CANADA; e-mail awong@physics.ubc.ca.

Winnie Wong-Ng, "Crystal Structures and Crystal Chemistry of Bi-Containing Compounds in the Bi-Sr-Ca-Cu-O System." Submitted to Study of High Temp. Supercond., edited by Anant Narlikar (Nova Publishing Co.). A215 MATLS, National Institute of Standards and Technology, Gaithersburg, MD 20899; telephone (301) 975-5791; telefax (301) 990-8729; e-mail wongng@tiber.nist.gov.

W. Wong-Ng, L. P. Cook, W. Greenwood, U. Balachandran, and M. Lanagan, "Preliminary Melting Data on Pb-2223 ([Bi:Pb]-Sr-Ca-Cu) Phase Under 7.5% O2." Submitted to Impact of Recent Adv. in Syn. and Proc. of Ceram. Supercond.: Proc. of the 99th Annual Mtg. of the Amer. Ceram. Soc., Cincinnati, Ohio, May 5-7, 1997. A215 MATLS, National Institute of Standards and Technology, Gaithersburg, MD 20899; telephone (301) 975-5791; telefax (301) 990-8729; e-mail wongng@tiber.nist.gov.

W. Wong-Ng, L. P. Cook, F. Jiang, W. Greenwood, U. Balachandran, and M. Lanagan, "Subsolidus-Phase Equilibria of Coexisting High-Tc Pb-2223 and 2212 Superconductors in the (Bi,Pb)-Sr-Ca-Cu-O System Under 7.5% O2." To be published in J. Mater. Res. A215 MATLS, National Institute of Standards and Technology, Gaithersburg, MD 20899; telephone (301) 975-5791; telefax (301) 990-8729; e-mail wongng@tiber.nist.gov.

N. J. Wu, Y. S. Chen, J. Y. Fan, and A. Ignatiev, "Infrared Photoresponse of (Mn,Sb) Doped-Pb(Zr,Ti)O3/YBa2Cu3O7 Heterostructure Detectors." Preprint #97:078; submitted to J. Appl. Phys. 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: heterostructure, pyroelectrics, infrared, detector.

Y. Xu, K. C. Goretta, M. M. Cuber, M. L. Burdt, L. R. Feng, Nan Chen, U. Balachandran, and M. Xu, "Processing Considerations for Adding Nanometer-Scale Oxides to Enhance Flux Pinning in High-Temperature Superconductors." Submitted to the Proc. of the Int. Cryogenic Eng. Conf. and the Int. Cryogenic Mater. Conf. (Joint ICMC-CEC 1997 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.

Bernd Zangger and Claudia Ambrosch-Draxl, "Geometry Effects on the Electronic Properties of YBa2Cu3O7." To be published in Z. Phys. B. Institut fuer Theoretische Physik, Universitaet Graz, Universitaetsplatz 5, A-8010 Graz, AUSTRIA; Claudia Ambrosch-Draxl's telephone +43 316 380 5235; telefax +43 316 380 9820; e-mail cad@cleopatra.kfunigraz.ac.at; Web site http://physik.kfunigraz.ac.at/~cad. 74.25.Jb; 31.15.Ew; 71.18.+y.

Z. Zhai, H. Srikanth, S. Sridhar, A. Erb, E. Walker, and R. Flukiger, "Observation of Coherent Josephson Response in the Non-Linear ab-Plane Microwave Impedance of YBa2Cu3O6.95 Single Crystals." To be published in Physica C: Proc. of the 5th Int. Conf. on Mater. and Mech. of Supercond. -- High-Temp. Supercond. (M^2S-HTSC V), Beijing, People's Republic of China, Feb. 28-Mar. 4, 1997. Department of Physics, Northeastern University, 360 Huntington Avenue, Boston, MA 02115; H. Srikanth's telephone (617) 373-2948; telefax (617) 373-2943; e-mail srikanth@neu.edu; preprint also available at cond-mat@xxx.lanl.gov (#9708030) or Web site http://sagar.physics.neu.edu/preprints.

F. C. Zhang and T. M. Rice, "An Anyon Superconducting Groundstate in Si MOSFETS?" Contact Stephan Haas, Theoretische Physik, ETH-Hoenggerberg, CH-8093 Zurich, SWITZERLAND; telephone +41 1 633 2575; telefax +41 1 633 1115; e-mail haas@itp.ethz.ch; preprint also available at cond-mat@xxx.lanl.gov (#9708050). 71.30.+h; 72.15.Rn; 73.20.Fz; 73.40.Qv.

ZHANG Yuheng, Fu Lan, Xu Xiaojun, and Mou Zhi, "A New Solution About the Thermal Activated Model of High-Tc Superconductor." Submitted to Phys. Lett. A. Structure Research Laboratory, University of Science and Technology of China, Hefei, Anhui 230026, PEOPLE'S REPUBLIC OF CHINA; telephone +86 551 360 2808; telefax +86 551 360 2803; e-mail zhangyh@email.sc.ustc.edu.cn. Key words: high-Tc superconductor, thermal activated model, flux lines, forward hopping, backward hopping. 74.60.Ge; 74.25.Fy; 74.20.Hi.

Y. G. Zhao, S. Y. Xiong, Y. P. Li, B. Zhang, S. S. Fan, B. Yin, J. W. Li, S. Q. Guo, W. H. Tang, G. H. Rao, D. J. Dong, B. S. Cao, and B. L. Gu, "Structural, Transport and Magnetic Properties of PrBa2-xSrxCu3O7-d." To be published in Phys. Rev. B. Department of Physics, Tsinghua University, Beijing 100084, PEOPLE'S REPUBLIC OF CHINA. 74.62.Dh; 74.25.Fy; 74.25.Ha.

(An * indicates a previously listed event.)

Feb. 2 - 4, 1998: International Symposium on Processing and Critical Current of HTS, Wagga Wagga, New South Wales, Australia. The main topics of the symposium are: single-crystal growth; powder synthesis and novel processing; microstructure and properties; flux pinning and dynamics; two-dimensional behavior; transport, magnetic, and mechanical properties; processing for the development of flux pinning centers; fabrication of wires, tapes, magnets, and bulk materials; and applications and future trends. Papers to be published in a special issue of Superconductor Sci. and Technol. Abstract deadline, October 15, 1997. For information, contact Pavel N. Mikheenko, Centre for Superconducting & Electronic Materials, University of Wollongong, Northfields Avenue, Wollongong, NSW 2500, Australia; telephone +61 42 215726; telefax +61 42 215731.

The information contained herein is intended for limited distribution. Readers are expected to respect the rights of the authors.

Please address all contributions and inquiries to: Dr. Sreeparna Mitra, A219 Physics,

Ames Laboratory/Iowa State University,

Ames, Iowa 50011-3020.

Telephone: (515) 294-3877 Telefax: (515) 294-1134.

E-mail: MITRA@AMESLAB.GOV or MITRA@IASTATE.EDU.

Project Director/Editor: Sreeparna Mitra

Science Editor: John R. Clem

High-Tc Update, Vol. 11, #16, August 15, 1997.