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, and other agencies, organizations, and individuals.
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NOTA BENE:
Theory
In conventional superconductors, the most convincing evidence of the mechanism responsible for superconductivity comes from tunneling spectroscopy, in which a clear image of the electron-phonon interaction is revealed. The observed structure in the current-voltage characteristics at the phonon energies can be used to measure the electron-phonon spectral density alpha^2F(omega) by inverting the Eliashberg equations. J. P. Carbotte (McMaster) et al. note that in the high-Tc oxides, which have very short coherence lengths, infrared spectroscopy and inelastic neutron scattering are better methods for the investigation of the mechanism of superconductivity. In this preprint, the authors show that conducting carriers studied by means of infrared spectroscopy reveal strong coupling to a resonance structure in the spin-fluctuation spectrum seen by inelastic neutron scattering. The authors note that the coupling strength inferred from experiment is sufficient to account for high values of Tc, indicating the prominent role of spin excitations in the superconductivity of the high-Tc cuprates.
The effects of strong-coupling superconductivity on the normal-state electronic structure have been studied by Y. Yanase and K. Yamada (Kyoto). The authors explain pseudogap phenomena in the high-Tc cuprates as a precursor of strong-coupling superconductivity. They find that superconducting fluctuations, which are strongly diffusive within conventional weak-coupling theory, become propagating and have the character of preformed pairs in the strong-coupling case.
The fluctuation-exchange approximation (FLEX) has been extended by F. Schaefer et al. (Freie Universitaet Berlin) to include phase fluctuations self-consistently. The authors find that Tc, calculated using the Kosterlitz-Thouless criterion, is proportional to the superfluid density n_s in the underdoped regime, which is in accord with experimental findings. In this picture, Tc* is the critical temperature at which Cooper pairs are formed; the authors find that Tc* > Tc in the underdoped regime and Tc* ~~ Tc for the overdoped case.
The issues of confinement and Bose condensation for gauge models of high-Tc superconductors are studied in a preprint by N. Nagaosa (Tokyo) and P. A. Lee (MIT). The authors apply their results to study the temperature-doping (T-x) phase diagram in three regimes: (a) doping into the antiferromagnet (x << 1), (b) the underdoped region, in which the normal state is a pseudogap state described as d-wave pairing of fermions or a staggered flux phase, and (c) the overdoped region, in which the high-temperature phase is the strange-metal phase. The authors note that in the underdoped region there are three possible scenarios for the onset of the low-temperature superconducting phase: (i) a binding of paired fermions with bosons to form physical quasiparticles, (ii) Bose condensation of single bosons in the U(1) formulation, and (iii) pairing of two kinds of bosons in the SU(2) formulation.
Using the method of a continuous renormalization group around the Fermi surface, M. Disertori and V. Rivasseau (Ecole Polytechnique) have proved in two companion papers that a two-dimensional interacting system of fermions at low temperature T remains a Fermi liquid (analytic in the coupling constant lambda) for lambda <= c/|logT|, where c is some numerical constant. The authors note that this bound is one step towards a rigorous (nonperturbative) study of the BCS phase transition for many-fermion systems; it proves that in two dimensions the transition temperature, if any, must be nonperturbative in the coupling constant. In one paper (Part I), the authors deal with convergent contributions, and in the other (Part II), the authors deal with the renormalization of dangerous two-point subgraphs and complete the proof.
As shown in a preprint by G. Seibold and S. Varlamov (BTU Cottbus), vertex renormalization can lead to a substantial enhancement of the superconducting order parameter in a Peierls-distorted charge-density- wave (CDW) system when the chemical potential is located sufficiently inside one of the subbands. The authors' results provide a possible explanation for the linear relationship between Tc and the incommensurability as observed in the underdoped lanthanum cuprates.
Low-energy quasiparticle states, arising from scattering by single- particle potentials in d-wave superconductors, are addressed in a paper by I. Adagideli et al. (Illinois at Urbana-Champaign). After noting that sign variations in the superconducting pair potential lead to such states in the case of planar boundary scattering, the authors use the Andreev approximation to extend this approach to general single-particle potentials, such as those due to impurities. The authors also point out the index-theoretic origin of these low-energy states by making a connection with Witten's supersymmetric quantum mechanical model.
A preprint by M. J. Graf (Los Alamos) et al. shows that an isolated impurity in a spin-singlet d_[x^2-y^2] superconductor generates a d_[xy] order parameter with locally broken time-reversal symmetry. The origin of this effect is a coupling between the d_[x^2-y^2] and d_[xy] order parameter induced by spin-orbit scattering off the impurity. The signature of locally broken time-reversal symmetry is an induced orbital charge current near the impurity, which generates a localized magnetic field. The authors present a microscopic theory for the impurity- induced d_[xy] component, and discuss its spatial structure and the pattern of induced current and local magnetic field near the localized impurity spin.
According to a preprint by C. Grimaldi (EPFL) and L. Pietronero (Roma), the nonadiabatic regime of the electron-phonon interaction leads to behavior of some physically measurable quantities that is different from what is expected from the Migdal-Eliashberg theory. The authors identify the Pauli paramagnetic susceptibility chi as one of these quantities, and they show that the nonadiabatic corrections reduce chi with respect to its adiabatic limit. The authors also show that the nonadiabatic regime induces an isotope dependence of chi, which should be measurable.
It is shown in a preprint by M. Machida (JAERI and CREST) et al. that both microwave resonant absorption and multiple-branch structures in the I-V characteristics observed in intrinsic Josephson junctions are caused by dynamical breaking of charge neutrality inside the atomic-scale superconducting layers. The authors propose a Lagrangian for the time- dependent Lawrence-Doniach model incorporating this effect, and they use the resulting equations to prove that a longitudinal collective Josephson plasma mode exists and to show from numerical simulations that the branching behavior of the I-V curves can be almost completely reproduced.
According to a preprint by G. A. Levin and C. C. Almasan (Kent State), the resistive anisotropy of an anisotropic medium is determined by the ratio of the phase coherence lengths. In layered crystals where the interlayer transport is incoherent, the authors assert that the out-of- plane phase coherence length is fixed and temperature-independent. This leads to a temperature-dependent resistive anisotropy and to the coexistence of metallic in-plane and nonmetallic out-of-plane conductivities. The authors' approach provides a description of the c- axis conductivity in the highly nonclassical regime, characteristic of the layered cuprates.
A simple model for the linear temperature dependence of the electrical resistivity of layered cuprates is proposed in a preprint by T. M. Mishonov and M. T. Mishonov (Leuven). The authors model the layers as arrays of independent plane capacitors with area a_0^2, where a_0 is the lattice constant, and they calculate the in-plane electrical resistivity as being due to the scattering of charge carriers by thermal fluctuations of the electric charge in the conducting CuO2 planes. This mechanism is analogous to Rayleigh's explanation of why the sky is blue.
An asymptotic theory has been formulated by A. Badia (Zaragoza), which allows the London penetration depth lambda(T) to be obtained from magnetic force microscopy (MFM) measurements. The method is not restricted to any particular symmetry of the applied magnetic field.
A new theoretical formulation of nonequilibrium superconducting phenomena, including singlet and triplet pairing, has been developed by M. Eschrig (Northwestern). The author starts from the general Keldysh- Nambu-Gor'kov Green's functions in the quasiclassical approximation and represents them in terms of 2 x 2 spin-matrix distribution functions for particle-like and hole-like excitations. The resulting transport equations for the distribution functions may be interpreted as a generalization to the superconducting state of Landau's transport equation for the normal Fermi liquid of conduction electrons. The equations are well suited for numerical simulations of dynamical phenomena.
Calculations of the rate of planar Cu spin-lattice relaxation in the mixed state of YBa2Cu3O7-d due to vortex vibrations and electron spin- flip scattering have been carried out by R. Wortis et al. (McMaster). Since both mechanisms give position-dependent rates due to the presence of vortices, the magnetization recovery is characterized by a distribution of rates. The authors find that relaxation by vortex vibrations is too slow to be a significant factor in this material. Using a semiclassical model of Doppler-shifted d-wave quasiparticles with a linear dispersion around the nodes, the authors find that their calculation of the relaxation rate from electron spin-flip scattering shows partial agreement with experiment.
RBa2Cu3O7-d
As noted in a preprint by J. Demsar et al. (Ljubljana), time-resolved optical measurements give information on the quasiparticle relaxation dynamics in Y1-xCaxBa2Cu3O7-d, from which the evolution of the gap with doping and temperature can be systematically deduced. In this paper, these optical charge-channel pseudogap data are compared with the pseudogap obtained from the NMR Knight shift K_s, spin-polarized neutron scattering (SPNS), and single-particle tunneling measurements. The authors propose a simple energy-level diagram to explain the different gap magnitudes observed by different spectroscopies in YBa2Cu3O7-d. The authors propose that the spin gap Delta_s in NMR and SPNS corresponds to a triplet local pair state, while Delta_p in the charge-excitation spectrum corresponds to the pair dissociation energy. At optimum doping and in the overdoped state, an additional T-dependent gap Delta_[BCS] becomes evident, which closes at Tc, suggesting a crossover to a more conventional BCS-like scenario for superconductivity.
The optical conductivity in twinned single crystals of YBa2(Cu1- xNix)3O6+y has been determined by C. C. Homes (Brookhaven) et al. for a nominally pure system and for Ni concentrations of x = 0.0075 and 0.014 with oxygen dopings of = 0.60 (underdoped) and 0.95 (optimal) over a wide frequency range above and below Tc. The authors found an unusual feature in the conductivity at about 300 cm^[-1], which is sensitive to the presence of Ni but not to the oxygen content. By detwinning the crystals, the authors were able to determine that the 300 cm^[-1] feature was restricted to the chains and thus that Ni atoms are doped into both the CuO chains and the CuO2 planes. The authors present evidence that Ni acts either as a localization site, or an impurity scatterer and strong pair breaker, destroying the superconductivity along the chains and strongly reducing the anisotropy of the system at low frequency.
Results of electronic Raman-scattering experiments in YBa2Cu3O6+x with different doping levels x are reported by M. Opel (Garching) et al. The authors consider B_[2g] symmetry, analyze the data in terms of a memory- function approach, and obtain the dynamical relaxation rate Gamma(omega,T) and mass-enhancement factor 1 + lambda(omega,T) for the carriers. Starting from temperatures T > 180 K, the authors extrapolate Gamma(omega,T) and 1 + lambda(omega,T) to lower temperatures and recalculate the Raman spectra. The data at the lower temperatures show a loss of spectral weight relative to the extrapolated spectra for Tc < T < T* at all doping levels x. The loss in spectral weight is due to the opening of a pseudogap, and the observed value of T* is similar to the pseudogap temperature found in other experiments.
Contrasting behavior of the in-plane and out-of-plane magnetoresistance (MR) in heavily underdoped nonsuperconducting, antiferromagnetic (AF) YBa2Cu3O6+x (x <= 0.37) is reported by A. N. Lavrov et al. (CRIEPI). The out-of-plane MR (I||c) is positive over most of the temperature range and shows a sharp increase, by about two orders of magnitude, upon cooling through the Neel temperature T_N. A contribution associated with AF correlations is found to dominate the out-of-plane MR behavior for H||c from far above T_N, pointing to the key role of spin fluctuations in the out-of-plane transport. By contrast, the transverse in-plane MR (I||a or b; H||c) vs T is small and varies smoothly through T_N, implying that the development of the AF order has little effect on the in-plane resistivity.
A preprint by A. Hu et al. (Dresden) reports investigations of superconductivity and phase stability in solid-solution (Nd0.33Sm0.67)1+xBa2-xCu3O7-d powders with varying x that were synthesized in air. Two-kink superconducting transitions in the real part of the ac magnetic susceptibility were observed, which the authors discuss in terms of phase separation. Post-annealing in Ar resulted in a dramatic suppression of the solid solubility limits, and precipitates due to decomposition during the Ar treatments may act as new pinning centers.
Bi Cuprates
Systematic studies of stacks of a few (n <= 12) intrinsic tunnel junctions fabricated on the surface of Bi2Sr2CaCu2O8+d (Bi-2212) single crystals have been carried out by Y.-J. Doh et al. (POSTECH). The authors were able to tailor the number of junctions in a stack by progressively increasing the relative height of the stacks by ion-beam etching the material between stacks. The c-axis tunneling characteristics were measured in situ in a vacuum chamber at temperatures down to ~13 K. Using this technique in a single piece of crystal, the authors were able to exclude spurious effects arising from variations in the junction parameters. The authors found that (a) the tunneling resistance and the current-voltage curves are scaled by the surface-junction resistance, (b) the reduction in both the gap and the superconducting transition temperature of the surface conducting plane in contact with the normal metal is not caused by a variation in doping level but is caused by the proximity contact, and (c) in the low-bias region, the main features of an intrinsic junction are not affected by the presence of other junctions in the stack.
An experimental study of the temperature dependence of the thermoelectric coefficient L(T) = S(T)sigma(T) in Ag-doped (Bi1.6Pb0.4)Sr2Ca3(Cu1-xAgx)4O12+d (Bi-2234), where S(T) is the in-plane thermopower and sigma(T) is the in-plane conductivity, has been carried out by J. E. Rodriguez and A. Marino (Colombia) in the fluctuation region above Tc. The authors found that in the mean-field region, L(T) is not affected by thermodynamic fluctuations of the superconducting order parameter. For low Ag concentrations, the authors found that the experimental data for sigma are fit well by the Lawrence-Doniach model for layered superconductors in the mean-field region, and that the net fluctuation contribution to L(T) is almost zero because the fluctuation contributions due to S and sigma nearly cancel.
The ac losses in a silver-gold-alloy-sheathed Bi-2223 tape have been measured by B. des Ligneris (Sherbrooke) et al. using a null calorimetric method while a dc current was superimposed upon the ac current. As expected from computer simulations, the authors observed a minimum in the ac losses as a function of the dc current, an effect the authors call the Clem valley. A reduction of ac losses of approximately 50% at the valley minimum was observed, in accord with the calculations. At lower currents, the data fit the calculated behavior with a single parameter, a Meissner current of 21.8 A. The authors found that a surface-barrier current is incompatible with the data.
Other Cuprates
Nuclear quadrupole resonance (NQR) measurements of the [63]^Cu nuclear spin-lattice relaxation times in YBa2(Cu1-xNix)4O8 (x = 0, 0.005, 0.010, and 0.020) have been carried out by Y. Itoh (SRL-ISTEC) et al. using a spin-echo technique. The authors separately obtained the [63]^Cu NQR relaxation rate (1/T_1)_[HOST] due to spin fluctuations of the host Cu electrons and the Ni-induced [63]^Cu relaxation rate (1/tau_1). The results demonstrate that the Ni impurities destroy the superconducting long-range order but do not significantly affect either the pseudo spin- gap or the host Cu antiferromagnetic correlations.
As pointed out by P. Plibersek and P. F. Meier (Zurich), the nuclear quadrupole resonance (NQR) spectrum of strontium-doped La2CuO4 surprisingly resembles the NQR spectrum of La2CuO4 doped with excess oxygen, both spectra being dominated by a main peak and one principal satellite peak at similar frequencies. Using first-principles cluster calculations, the authors have investigated this coincidence by calculating the electric field gradient (EFG) at the central copper site of the cluster after replacing a lanthanum atom in the cluster with a strontium atom or adding an interstitial oxygen to the cluster. In each case, the EFG was increased by approximately 10%, leading unexpectedly to the explanation that the NQR spectra are only accidentally similar and that the origins are quite different. To explain the observed increase in frequency of both the main and satellite peaks in the NQR spectrum as the doping concentration is increased, the authors propose a model based on holes moving rapidly across the planar oxygen atoms.
The normal-state Ettingshausen coefficient P in La2-xSrxCuO4 (x = 0.03 - 0.35) has been measured by T. Plackowski and M. Matusiak (Wroclaw) and found to be of order 10^[-7]m^3K/J, which is characteristic of typical metals. The coefficient changes sign from positive to negative near x ~~ 0.07. The weak variation of P with x is in contrast to the behavior of other transport coefficients for La2-xSrxCuO4, such as the thermoelectric power or the Hall coefficient, which vary by more than two orders of magnitude with Sr doping.
The c-axis tunneling properties of both pristine Bi2Sr2CaCu2O8+d (Bi- 2212) and its intercalate HgBr2Bi2Sr2CaCu2O8+d (HgBr2/Bi-2212) have been measured by A. Yurgens (Chalmers) et al. in the temperature range 4.2- 250 K. Lithographically patterned 7-10 unit-cell-high mesa structures of these single crystals were investigated. Clear SIS-like tunneling curves for current applied in the c direction were observed. The dynamic conductance dI/dV vs V shows sharp peaks, corresponding to a superconducting gap edge, and a dip feature beyond the gap, followed by a wide maximum, which persists up to room temperature. The shape of the temperature dependence of the c-axis resistance does not change after intercalation, suggesting that coupling between CuO2 bilayers has little effect on the pseudogap.
The phonon densities of states in La1.475Nd0.4Sr0.125CuO4 and La1.9Sr0.1CuO4 have been measured by R. J. McQueeney (Los Alamos) et al. The ~70 meV phonon band, which appears due to hole doping in La1.9Sr0.1CuO4 is known to arise from strong electron-lattice coupling. This phonon band is strongly suppressed in the Nd-doped compound, for which Tc is also suppressed, suggesting a link between in-plane oxygen optical phonons and superconductivity. This suppression is attributed to hole localization, which becomes strong near the stripe-ordering condition of certain cuprates near x = 1/8 and competes with superconductivity.
Vortices
Intense pulsed current densities have been used by M. N. Kunchur (South Carolina) et al. to overcome vortex pinning in YBa2Cu3O7-d down to low temperatures (T/Tc ~ 0.02) and drive flux flow to the point of vortex instability over the entire temperature range. The critical resistivity at the point of instability rho* is proportional to B and shows good agreement with rho* ~~ 2rho_f ~~ 2rho_nB/H_[c2]. Contrary to some speculation, rho_n saturates to a residual value, much like an ordinary metal, and the vortex dissipation continues to be conventional as T --> 0.
Lattice Monte Carlo simulations (5 x 10^4 hours of a single Cray node's capacity) have been used by K. Kajantie (Helsinki) et al. to study the interactions and macroscopic behavior of a large number of vortices in the three-dimensional U(1) gauge+Higgs field theory in an external magnetic field. The authors studied both type-I and type-II superconductors and obtained results relevant for superconductors, some models of cosmic strings, and the electroweak phase transition in a magnetic field.
Activation energies for vortex motion through the vortex-free region at the surface of a superconductor in a parallel magnetic field have been calculated by G. C. Kim et al. (Pusan National). The authors also calculate magnetic relaxation for the surface barrier and find very different rates for vortex entry and exit.
The magnetic field dependence of the critical current has been studied by S. S. Banerjee (TIFR-Mumbai) et al. in single-crystal samples of the weak-pinning type-II superconductor 1H-NbSe2 in the high-temperature, low-field region of the H-T phase space, in the vicinity of the reentrant peak effect. The experimental results demonstrate various pinning regimes. A collectively pinned quasi-ordered solid occurs in intermediate fields but is destabilized in favor of disordered vortex phases in either higher fields near H_[c2] or lower fields near H_[c1]. The temperature evolution of the pinning behavior demonstrates how the amorphous limit (where the correlation volume is nearly field independent) is approached near the so-called nose region of the reentrant peak-effect boundary. Moreover, the data show that the rapid approach to the amorphous limit naturally yields a peak effect (a peak in the critical current) in the high-field regime, but yields a plateau effect in the low-field regime. With increasing effective disorder, the peak effect shifts away from H_[c2] and resembles a fishtail anomaly.
Using both stability analyses of the time-independent Ginzburg-Landau equations and numerical solutions of the time-dependent Ginzburg-Landau equations, M. Ghinovker et al. (Bar-Ilan) have studied the dynamics of supercooled normal domains in type-I superconductors. In zero magnetic field, the authors find that there is an explosive nucleation of superconductivity as the temperature is lowered, leading to a metastable mixed state consisting of Abrikosov vortices and antivortices.
Using a two-coil mutual-inductance method, A. A. Pesetski and T. R. Lemberger (Ohio State) have measured the complex resistivity rho_v(T,B) of pinned vortices in c-axis pulsed-laser-deposited (PLD) YBa2Cu3O7-d films with magnetic fields B applied perpendicular to the film. At low frequencies (< 100 kHz), rho_v is inductive and is inversely proportional to the Labusch parameter, the average vortex pinning-force constant kappa_[exp]. The observed weakening of kappa_[exp] with B is consistent with a simple model based on linear pinning defects. Adding classical thermal fluctuations to the model in a simple way explains the observed linear T dependence of rho_v below ~15 K and provides reasonable values for the effective radius (3-8 Angstroms) of the defects and the depth of the pinning potential. To date, however, no sufficient theory exists to explain the data between ~15 K and the vortex-glass melting temperature.
Films
Narrow YBa2Cu3O7-d step-edge junctions (width w=0.8-18 micrometers) in applied magnetic fields up to B_a ~35 mT have been studied by E. E. Mitchell et al. (CSIRO). The authors used the magnetic-field dependence of the junction critical current I_c(B_a) to study the penetration of vortices into the film. At 77 K, the authors found that the junctions exhibit jumps in I_c(B_a) due to the creation, annihilation, and motion of a small number of vortices close to the junction. The fields at which the jumps occur and the number of jumps measured for a particular B_a show a dependence on w; the data suggest that field enhancement affects the penetration of vortices and support a field enhancement factor that is proportional to w.
Kinetic roughening phenomena of flux fronts penetrating into superconducting thin films have been studied by R. Surdeanu et al. (Amsterdam) using a high-resolution magneto-optical technique. The roughening exponent (alpha = 0.64) and growth exponent (beta = 0.65) obtained from a dynamic scaling analysis of the initial stage of flux penetration and at small length scales are characteristic of static- disorder-dominated nonlinear diffusion. At large length scales, the exponent alpha = 0.46 indicates a transition towards dynamic stochastic disorder, similar to the behavior of Kardar-Parisi-Zhang systems. There is a striking similarity to the behavior of combustion fronts in burning paper.
As shown by C. W. Schneider et al. (Augsburg), appropriate doping of the electrodes of high-Tc Josephson junctions provides a means to systematically adjust the junctions' electronic properties. The authors demonstrate this effect in grain-boundary junctions in bicrystalline Ca- doped YBa2Cu3O7-d films. The authors found that the critical current density at 4.2 K is strongly increased and the normal-state resistivity significantly decreased in comparison with the values obtained for equivalent junctions in undoped films.
The atomic structure and composition of interface-engineered YBa2Cu3O7-d edge junctions that showed good, reproducible critical currents I_c (1 sigma spread in I_c of less than 8% for 100 junctions) have been investigated by J. G. Wen (SRL-ISTEC) et al. using transmission electron microscopy (TEM). The micrographs showed a thin barrier (1-2 nm) homogeneously covering the ion-milled edge of the base YBa2Cu3O7-d film, although there is no barrier-deposition and annealing process. The authors determined that the barrier is a Ba-based perovskite-like structure (Y1-xCux)BaOy with x < 0.5. Evidently a thin amorphous layer whose composition deviates from YBa2Cu3O7-d is formed because of preferential sputtering of Cu; this amorphous layer recrystallizes into the nonequilibrium phase (Y1-xCux)BaOy after heating to the deposition temperature.
Measurements of the magnetic penetration depth lambda(T) in YBa2Cu3O7-d films at various d are reported by B. R. Boyce et al. (Ohio State). At optimal doping, the authors find that critical fluctuation effects are absent, and that 1/lambda^2(T) vs T from 4 K to 0.99 Tc is well described by d-wave BCS strong-coupling theory with a gap parameter Delta_0(0)/k_BTc ~~ 3.3. This implies that the T dependence of lambda(T) comes largely from single-particle excitations. As in crystals, underdoping reduces the superfluid density, n_s(0) proportional to 1/lambda^2(0), without affecting the low-T slope or curvature of lambda(T). The authors show that these results, as well as heat-capacity measurements, are well described by an ad hoc model in which superfluid is lost from regions of the Fermi surface occupied by the pseudogap, while the low-lying excitations near the nodes remain unaffected.
A preprint by A. V. Nikulov (Chernogolovka) et al. reports a comparison of the resistive properties of Bi2Sr2CaCu2O8+d (Bi-2212) in the mixed state with those of thin films of conventional superconductors with weak disorder (amorphous Nb1-xOx films) and strong disorder (Nb1-xOx films with small grain structure). The authors find that the quantitative difference between thin films with weak and strong disorder is greater than the difference between layered high-temperature superconductors and conventional superconductors, showing that the dimensionality of the system, rather than the critical temperature, is the key factor ruling fluctuation effects.
Microstructural characterizations of rolling-assisted biaxially textured substrates (RABiTS) are described in a preprint by E. Y. Sun et al. (Oak Ridge) using high-resolution transmission electron microscopy (TEM) and high-resolution analytical electron microscopy (AEM). The authors report details of their studies of RABiT substrates with a multilayer configuration YSZ (0.2 micrometer)/CeO2 (0.9 micrometer)/Ni (125 micrometer).
Applications
The design, fabrication, and testing of a first-order sigma-delta modulator using a high-temperature superconducting multilayer technology with bicrystal Josephson junctions are reported in a preprint by B. Ruck et al. (Juelich). The circuit consists of a single flux quantum (SFQ) pulse generator, a Josephson transmission line, a comparator, an integrator, and an output stage. The authors report that the basic function of this device has been verified experimentally.
The development of a hybrid superconductor-magnet bearing system based on passive magnetic levitation and the flux-pinning effect of high- temperature superconductivity is reported by E. J. Lee (TCSUH) et al. The rationale lies in the unique capability of a high-temperature superconductor to enhance system stability passively without power consumption. Characterization experiments have been conducted to understand the bearing's dynamic behavior and to estimate the required motor torque for its driving system design. The authors discuss the importance of several critical design factors.
Other Activities
A preprint by H.-Y. Lee (UCLA) et al. reports a theoretical study of spin excitations in a two-dimensional p-wave superconductor as a model of the recently discovered superconductor Sr2RuO4. The authors calculate the polarization and spectrum of spin-wave excitations and discuss experimental consequences.
Overviews
Single-crystal growth of the high-temperature superconductor YBa2Cu3O7-d has been reviewed by D. K. Aswal (Shizuoka University and BARC-Mumbai) et al. The authors discuss the critical parameters and crystallization mechanisms involved in the growth of YBa2Cu3O7-d single crystals from self-flux with an excess of BaO and CuO. The growth of YBa2Cu3O7-d crystals with the aid of an alkali halide (NaCl/KCl) flux and the effect of silver additions also are presented. In addition, the authors briefly summarize the growth of large YBa2Cu3O7-d single crystals using the top-seeded solution-growth technique (72 refs.).
An overview of stripe phases in high-temperature superconductors has been prepared by V. J. Emery (Brookhaven) et al. Stripe phases are predicted and observed to occur in a class of strongly correlated materials describable as doped antiferromagnets, of which the copper- oxide superconductors are the most prominent representatives. The authors note that the existence of stripe correlations necessitates the development of new principles for describing charge transport, especially superconductivity, in these materials (44 refs.).
Ph.D. Theses
Effects associated with quasiparticle transport in clean normal/superconducting (N/S) proximity systems have been examined theoretically in the Ph.D. thesis of A. L. Fauchere (ETH Zurich). The author finds two phases in the magnetic field vs temperature (H-T) phase diagram when the N/S interface is subjected to a parallel magnetic field: a diamagnetic state (at low temperature and field) where the applied field is effectively screened, and a normal state where the magnetic field penetrates into the normal metal. The author also considers transport in Josephson junctions with unconventional superconductors in which the current-phase relation exhibits a double frequency, and he proposes a design for a quantum computer that exploits this pi periodicity (186 refs.).
In the Ph.D. thesis of V. Berseth (EPFL), the author describes the results of transport experiments using nine contacts on the surface of a high-quality YBa2Cu3O7-d single crystal. Both guided vortex motion along twin boundaries and the mixed-state Hall effect were observed as a function of the direction of the current in the ab plane. The Hall- resistivity scaling law rho_[xy] = A[rho]_[xx]^^[beta] was found to hold, with beta = 2 for magnetic fields parallel to the twin boundaries and beta = 1.4 for a tilted magnetic field. The author also reviews the experimental data on the mixed-state Hall effect and discusses theoretical models for the above scaling law and the sign reversal of the Hall effect (165 refs.).
Contributed by John R. Clem
Contents: Preprints begin on page 7; Coming Events begin on page 14; and FYI is on page 15.
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PREPRINTS To obtain a particular preprint, contact the first author at the address given at the end of the citation. Help us expand this list by sending us your complete preprint. Please specify where and when your paper was submitted. An * next to an entry indicates it is a correction or revision of a previous entry. PACS codes and/or key words are given at the end of the citation.
C. C. Abilio, P. Butaud, Th. Fournier, B. Pannetier, J. Vidal, S. Tedesco, and B. Dalzotto, "Magnetic Field Induced Localization in a Two- Dimensional Superconducting Wire Network." Submitted to Phys. Rev. Lett. Centre de Recherches sur les Tres Basses Temperatures, Laboratoire associe a l'Universite Joseph Fourier, CNRS, 25 Av. des Martyrs, BP 166, F-38042 Grenoble Cedex 9, FRANCE; telephone +33 4 7688 1000; telefax +33 4 7687 5060; e-mail abilio@labs.polycnrs-gre.fr; preprint also available at http://xxx.lanl.gov/abs/cond-mat/9907187.
Inanc Adagideli, Paul M. Goldbart, Alexander Shnirman, and Ali Yazdani, "Low-Energy Quasiparticle States Near Extended Scatterers in d-Wave Superconductors and Their Connection with SUSY Quantum Mechanics." Department of Physics and Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL 61801; Paul M. Goldbart's e- mail paul@paul.physics.uiuc.edu; preprint also available at http://xxx.lanl.gov/abs/cond-mat/9907245. 74.62.Dh; 74.72.-h; 03.65.Sq; 11.30.Pb; 61.16.Ch.
D. F. Agterberg, Victor Barzykin, and Lev P. Gor'kov, "Exotic Ground States and Impurities in Multiband Superconductors." National High Magnetic Field Laboratory, Florida State University, 1800 East Paul Dirac Drive, Tallahassee, FL 32310; Victor Barzykin's e-mail barzykin@magnet.fsu.edu; preprint also available at http://xxx.lanl.gov/abs/cond-mat/9907331.
D. K. Aswal, Y. Hayakawa, S. K. Gupta, V. C. Sahni, and M. Kumagawa, "Crystal Growth of High-Temperature Oxide Superconductor YBa2Cu3Ox." To be published in Recent Research Developments in Crystal Growth Research, (Transworld Publications, India). Research Institute of Electronics, Shizuoka University, 3-5-1 Johoku, Hamamatsu 432-8011, JAPAN; telephone and telefax +81 53 478 1338; e-mail roaswal@eng.shizuoka.ac.jp.
A. Badia, "Asymptotic Theory for the Inverse Problem in the Magnetic Force Microscopy of Superconductors." To be published in Phys. Rev. B. Departamento de Fisica de la Materia Condensada, C.P.S.I. Universidad de Zaragoza, c/Maria de Luna 3, E-50015 Zaragoza, SPAIN; e-mail anabadia@posta.unizar.es. 74.25.Ha; 07.79.Pk; 02.30.Dk.
S. S. Banerjee, S. Ramakrishnan, A. K. Grover, G. Ravikumar, P. K. Mishra, V. C. Sahni, C. V. Tomy, G. Balakrishnan, D. McK. Paul, P. L. Gammel, D. J. Bishop, E. Bucher, M. J. Higgins, and S. Bhattacharya, "Peak Effect, Fishtail Effect and Plateau Effect: The Reentrant Amorphization of Vortex Matter in 2H-NbSe2." Submitted to Phys. Rev. B. Department of Condensed Matter Physics and Material Science, Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400005, INDIA; telephone +91 22 215-2971 or -2979; telefax +91 22 215- 2110 or -2181; e-mail sb@tifr.res.in; preprint also available at http://xxx.lanl.gov/abs/cond-mat/9907111. Key words: peak effect, fishtail effect, plateau effect, reentrance. 64.70.Dv; 74.60.Ge; 74.25.Dw; 74.60.Ec; 74.60.Jg.
L. Benfatto, A. Perali, C. Castellani, and M. Grilli, "Kosterlitz- Thouless vs Ginzburg-Landau Description of 2D Superconducting Fluctuations." Dipartimento di Fisica, Universita di Roma 'La Sapienza' and Istituto Nazionale Fisica della Materia, Unita di Roma 1, P. Aldo Moro 2, I-00185 Rome, ITALY; A. Perali's e-mail andrea.perali@roma1.infn.it; preprint also available at http://xxx.lanl.gov/abs/cond-mat/9906384. 74.20.De; 74.20.Mn; 71.10.-w.
Vincent Berseth, "Mixed State Hall Effect in a Twinned YBa2Cu3O7-d Single Crystal." Submitted as a Ph.D. thesis (Ecole Polytechnique Federale de Lausanne). Institut de Genie Atomique, Departement de Physique, Ecole Polytechnique Federale de Lausanne, CH-1015 Lausanne, SWITZERLAND; e-mail vincent.berseth@epfl.ch; preprint only available from http://xxx.lanl.gov/abs/cond-mat/9907091 or ftp://igahpse.epfl.ch/pub/supra.
Ch. Bertrand, Ph. Galez, R. E. Gladyshevskii, and J. L. Jorda, "The Pr(Ba1-xPrx)2Cu3O7+d Solid Solution: A Crystal Structure and Phase Diagram Study." To be published in Physica C (in press). Contact Ph. Galez, LAIMAN, Universite de Savoie-ESIA, BP 806, F-74016 Annecy Cedex, FRANCE; telephone +33 4 50 09 2204; telefax +33 4 50 09 2379; e-mail philippe.galez@univ-savoie.fr. Key words: Pr(Ba1-xPrx)2Cu3O7+d, high- Tc superconductor family, substitution effects, crystal structure, phase diagram.
H. Bitterlich, W. Loeser, G. Behr, K. Nenkov, G. Fuchs, A. Guembel, and L. Schultz, "Metallurgy, Superconductivity and Field-Dependent Magnetic Ordering in TbxEr1-xNi2B2C." To be published in Physica C (in press). Institut fuer Festkoerper- und Werkstofforschung Dresden, Postfach 270016, D-01171 Dresden, GERMANY; telefax +49 351 4659-422 or -541; e- mail h.bitterlich@ifw-dresden.de. Key words: borocarbides, TbxEr1- xNi2B2C, superconductivity, magnetic order. 74.70.Dd.
Brent R. Boyce, Kathleen M. Paget, and Thomas R. Lemberger, "Effect of the Pseudogap on the Mean-Field Magnetic Penetration Depth of YBa2Cu3O7- d Thin Films." Submitted to Phys. Rev. Lett. Department of Physics, Ohio State University, 174 West 18th Avenue, Columbus, OH 43210-1106; telephone (614) 292-7800 or -5713; telefax (614) 292-7557; e-mail boyce@mps.ohio-state.edu; preprint also available at http://xxx.lanl.gov/abs/cond-mat/9907196. 74.25.Fy; 74.25.Nf; 74.40.+k; 74.76.Bz.
Fabian Braun and Jan von Delft, "Fixed-N Superconductivity: The Exact Crossover from the Bulk to the Few-Electron Limit." To be published in Adv. Solid State Phys., Vol. 39. Institute fuer Theoretische Festkoerperphysik, Universitaet Karlsruhe, D-76128 Karlsruhe, GERMANY; e-mail fbraun@tfp.physik.uni-karlsruhe.de; preprint also available at http://xxx.lanl.gov/abs/cond-mat/9907402.
V. Bruyndoncx, L. Van Look, M. Verschuere, and V. V. Moshchalkov, "Dimensional Crossover in a Mesoscopic Superconducting Loop of Finite Width." To be published in Phys. Rev. B. Laboratorium voor Vaste- Stoffysica en Magnetisme, Katholieke Universiteit Leuven, Celestijnenlaan 200 D, B-3001 Leuven, BELGIUM; telephone +32 16 32 7164; telefax +32 16 32 7983; e-mail vital.bruyndoncx@fys.kuleuven.ac.be; preprint also available at http://xxx.lanl.gov/abs/cond-mat/9907341. 74.60.Ec; 74.25.Dw; 73.23.-b; 74.20.De; 74.76.-w.
H. Burkhardt, A. Rauther, and M. Schilling, "Microwave and dc Transport in YBa2Cu3O7 Ramp-Edge Josephson Junction Arrays." To be published in Physica C (in press). Institut fuer Angewandte Physik und Zentrum fuer Mikrostrukturforschung, Universitaet Hamburg, Jungiusstrasse 11, D-20355 Hamburg, GERMANY. Key words: Josephson junction, array, critical current, spread, temperature dependence.
J. P. Carbotte, E. Schachinger, and D. N. Basov, "Coupling Strength of Charge Carriers to Spin Fluctuations in High-Temperature Superconductors." Submitted to Nature. Department of Physics and Astronomy, McMaster University, Hamilton, Ontario, CANADA L8S 4M1; E. Schachinger's e-mail at Technische Universitaet Graz schachinger@itp.tu- graz.ac.at; preprint also available at http://xxx.lanl.gov/abs/cond- mat/9907338.
J. Demsar, K. Zagar, V. V. Kabanov, and D. Mihailovic, "Low-Energy Electronic Structure in Y1-xCaxBa2Cu3O7-d: Comparison of Time-Resolved Optical Spectroscopy, NMR, Neutron and Tunneling Data." Presented at University of Miami Conf. on High Temp. Supercond. (HTS99), Miami, Fla., Jan. 7-13, 1999. Jozef Stefan Institute, Jamova 39, 1001 Ljubljana, SLOVENIA; V. V. Kabanov's e-mail viktor.kabanov@ijs.si; preprint also available at http://xxx.lanl.gov/abs/cond-mat/9907028.
B. des Ligneris, Marcel Aubin, J. Cave, W. Zhu, and P. Dolez, "Decrease of ac Losses in High Tc Superconducting Tapes by Application of a dc Current." Submitted to the Proc. of the Int. Cryogenic Eng. Conf. and the Int. Cryogenic Mater. Conf. (CEC/ICMC), Montreal, Quebec, Canada, July 12-16, 1999. Departement de Physique and Centre de Recherche en Physique du Solide, Universite de Sherbrooke, 2500 Bd de I'Universite, Sherbrooke, Quebec, CANADA J1K 2R1; telephone (819) 821-8000, ext. 3040 or 3018; telefax (819) 821-8046; e-mail bligneri@physique.usherb.ca; preprint also available at http://xxx.lanl.gov/abs/cond-mat/9907271.
M. Disertori and V. Rivasseau, "Interacting Fermi Liquid in Two Dimensions at Finite Temperature -- Part I: Convergent Attributions." Centre de Physique Theorique, CNRS UPR 14, Ecole Polytechnique, F-91128 Palaiseau Cedex, FRANCE; V. Rivasseau's e-mail rivass@cpht.polytechnique.fr; preprint also available at http://xxx.lanl.gov/abs/cond-mat/9907130.
M. Disertori and V. Rivasseau, "Interacting Fermi Liquid in Two Dimensions at Finite Temperature -- Part II: Renormalization." Centre de Physique Theorique, CNRS UPR 14, Ecole Polytechnique, F-91128 Palaiseau Cedex, FRANCE; V. Rivasseau's e-mail rivass@cpht.polytechnique.fr; preprint also available at http://xxx.lanl.gov/abs/cond-mat/9907131.
Yong-Joo Doh, Hu-Jong Lee, and Hyun-Sik Chang, "Progressive Evolution of Tunneling Characteristics of In-Situ Fabricated Intrinsic Josephson Junctions in Bi2Sr2CaCu2O8+d Single Crystals." Submitted to Phys. Rev. B. Department of Physics, Pohang University of Science and Technology, Pohang 790-784, SOUTH KOREA; telephone +81 562 279 6704; telefax +81 562 279 6988; e-mail doooh@anyon.postech.ac.kr; preprint also available at http://xxx.lanl.gov/abs/cond-mat/9907251.
V. J. Emery, S. A. Kivelson, and J. M. Tranquada, "Stripe Phases in High Temperature Superconductors." To be published in Proc. Natl. Acad. Sci. Department of Physics, Brookhaven National Laboratory, Upton, NY 11973- 5000; J. M. Tranquada's e-mail jtran@bnl.gov; preprint also available at http://xxx.lanl.gov/abs/cond-mat/9907228.
M. Eschrig, "Distribution Functions in Non-Equilibrium Theory of Superconductivity." Department of Physics and Astronomy, Northwestern University, Evanston, IL 60208; e-mail eschrig@snowmass.phys.nwu.edu; preprint also available at http://xxx.lanl.gov/abs/cond-mat/9907312.
Alban Luc Andre Fauchere, "Transport and Magnetism in Mesoscopic Superconductors." Submitted as a Ph.D. thesis (ETH Zurich). Theoretische Physik, Eidgenoessische Technische Hochschule, CH-8093 Zurich, SWITZERLAND; e-mail fauchere@itp.phys.ethz.ch; preprint also available at http://xxx.lanl.gov/abs/cond-mat/9905258.
B. L. Fisher, K. C. Goretta, N. C. Harris, U. Balachandran, and Norimitsu Murayama, "Critical Current Densities in Bi-2223 Sinter Forgings." Submitted to the Proc. of the Int. Cryogenic Mater. Conf. (ICMC'99), Montreal, Quebec, Canada, July 12-16, 1999. Contact Janice Coble, Materials Science Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439; telephone (630) 252-5497; telefax (630) 252-9595; e-mail coble@anl.gov.
N. J. Garfield, M. A. Howson, G. Yang, and S. Abell, "Specific Heat of a DyBa2Cu3O7-y Single Crystal in Magnetic Fields up to 8 T." To be published in Physica C (in press). Contact M. A. Howson, Department of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, UNITED KINGDOM; telephone +44 113 233 3841; telefax +44 113 233 3846, ext. 900; e-mail m.a.howson@leeds.ac.uk. Key words: specific heat, DyBa2Cu3O7-y, lowest Landau level.
M. Ghinovker, I. Shapiro, and B. Ya. Shapiro, "Nucleation of Superconductivity in a Type-I Supercooled System." To be published in Phys. Lett. A. Contact B. Ya. Shapiro, Institute of Superconductivity, Department of Physics, Bar-Ilan University, Ramat Gan 52900, ISRAEL. 74.20.De; 74.60.Ge.
A. A. Golubov, "Interface Resistance in Ferromagnet/Superconductor Junctions." To be published in Physica C: Proc. of the Fifth Twente Workshop -- Digital Applications, Josephson Junctions and Sensors, University of Twente, The Netherlands, April 25-28, 1999. Department of Applied Physics, University of Twente, P.O. Box 217, 7500 AE Enschede, THE NETHERLANDS; telephone +31 53 489 3122; telefax +31 53 489 1099; e- mail a.golubov@tn.utwente.nl; preprint also available at http://xxx.lanl.gov/abs/cond-mat/9907194. Key words: interface resistance, ferromagnet/superconductor junctions, spin-polarized tunneling.
M. J. Graf, A. V. Balatsky, and J. A. Sauls, "Local Time-Reversal Symmetry Breaking in d_[x^2-y^2] Superconductors." Preprint #LA-UR-99- 1349. Center for Materials Science, Mail Stop K765, Los Alamos National Laboratory, Los Alamos, NM 87545; telephone (505) 665-3035; telefax (505) 665-2992; e-mail graf@lanl.gov; preprint also available at http://xxx.lanl.gov/abs/cond-mat/9907300. 74.25.Bt; 74.62.Dh.
C. Grimaldi and L. Pietronero, "Pauli Susceptibility of Nonadiabatic Fermi Liquids." To be published in Europhys. Lett. Departement de Microtechnique IPM, Ecole Polytechnique Federale de Lausanne, CH-1015 Lausanne, SWITZERLAND; telephone +41 21 693 5825; telefax +41 21 693 3866; e-mail claudio.grimaldi@epfl.ch; preprint also available at http://xxx.lanl.gov/abs/cond-mat/9904151. 63.20.Kr; 71.38.+i; 76.30.-v.
C. C. Homes, D. A. Bonn, Ruixing Liang, W. N. Hardy, D. N Basov, T. Timusk, and B. P. Clayman, "The Effect of Ni Impurities on the Optical Properties of YBa2Cu3O6+y." 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; 74.62.Dh; 74.72.Bk.
A. Hu, G. Krabbes, P. Schaetzle, and W. Bieger, "On the Superconductivity and Phase Stability of (Nd0.33Sm0.67)1+xBa2-xCu3O7-d." To be published in Physica C. Institut fuer Festkoerper- und Werkstofforschung Dresden, Abt. 13, Postfach 270016, D-01171 Dresden, GERMANY; e-mail a.hu@ifw-dresden.de.
Yutaka Itoh, Takato Machi, Nobuaki Watanabe, and Naoki Koshizuka, "Cu NQR Study of Impurity and Host Spin Dynamics in YBa2(Cu1-xNix)4O8." Submitted to J. Phys. Soc. Jpn. Superconductivity Research Laboratory, International Superconductivity Technology Center (ISTEC), 10-13 Shinonome 1-chome, Koto-ku, Tokyo 135, JAPAN. Key words: NQR, high-Tc cuprate, magnetic impurity Ni, pseudo spin-gap.
K. Kajantie, M. Laine, T. Neuhaus, A. Rajantie, and K. Rummukainen, "Statistical Mechanics of Vortices from Field Theory." Preprint #CERN- TH/99-168. Department of Physics, University of Helsinki, P.O. Box 9, FIN-00014 Helsinki, FINLAND; e-mail keijo.kajantie@helsinki.fi; M. Laine's e-mail at Geneva, Switzerland mikko.laine@cern.ch; preprint also available at hep-lat@xxx.lanl.gov (#9906028).
Hae-Young Kee, Yong Baek Kim, and Kazumi Maki, "Spin Waves in a Two Dimensional p-Wave Superconductor: Sr2RuO4." Department of Physics, University of California, Los Angeles, CA 90095; e-mail hykee@cooper.physics.ucla.edu; preprint also available at http://xxx.lanl.gov/abs/cond-mat/9907276. 74.25.-q; 74.25.Nf.
G. C. Kim, M. Y. Cheon, and Y. C. Kim, "Activation Energies and Magnetic Relaxation for the Surface Barrier in 3D Type-II Superconductor." To be published in Physica C (in press). Contact M. Y. Cheon, Department of Physics, Pusan National University, Pusan 609-735, SOUTH KOREA; telephone +82 51 510 2224; telefax +82 51 513 7664; e-mail mycheon@hyowon.pusan.ac.kr. Key words: flux creep, activation energy.
A. Knizhnik, Y. Direktovich, G. M. Reisner, D. Goldschmidt, C. G. Kuper, and Y. Eckstein, "Transport Measurements in the 1-2-3 System CLBLCO in Both the Oxygen-Underdoped and -Overdoped Regions." To be published in Physica C (in press). Contact C. G. Kuper, Department of Physics and Crown Center for Superconductivity, Technion, Israel Institute of Technology, Haifa 32000, ISRAEL; telephone +972 4 829 3903; telefax +972 4 822 1514; e-mail charles@physics.technion.ac.il. Key words: superconducting transition temperature, high Tc, 1-2-3 materials, oxygen-doping, thermoelectric power, resistivity. 74.72.Jt; 74.25.Fy; 74.62.-c; 74.62.Dh.
R. Koch and W. Jutzi, "Input and Output Interfaces Between RSFQ and Semiconductor Circuits." To be published in Physica C (in press). Contact W. Jutzi, Institut fuer Elektrotechnische Grundlagen der Informatik, Universitaet Karlsruhe, Hertzstrasse 16, D-76187 Karlsruhe, GERMANY; telephone +49 721 608 4446; telefax +49 721 757925; e-mail jutzi@iegi01.etec.uni-karlsruhe.de. Key words: input interface, output interface, RSFQ, semiconductor circuits.
A. A. Kordyuk, G. Krabbes, V. V. Nemoshkalenko, and R. V. Viznichenko, "Surface Influence on Flux Penetration into HTS Bulks." Submitted to Physica B: Proc. of the 22nd Int. Conf. on Low Temp. Phys. (LT22), Helsinki, Finland, Aug. 5-11, 1999. Institute of Metal Physics, National Academy of Sciences of Ukraine, 36 Vernadsky str., Kyiv 252680, UKRAINE; e-mail kord@imp.kiev.ua; preprint also available at http://xxx.lanl.gov/abs/cond-mat/9907053. Key words: surface barrier, ac losses, resonance oscillation technique, melt-processed HTS.
L. Kowalewski, M. M. Nogala, M. Thomas, and R. J. Wojciechowski, "Electronic Tunneling into the Vortex Lattice States in Superconductors in High Magnetic Field." To be published in Physica C (in press). Institute of Physics, A. Mickiewicz University, ul. Umultowska 85, PL- 61614 Poznan, POLAND; telephone +48 61 821 7011, ext. 340; telefax +48 61 821 7991; e-mail leoko@main.amu.edu.pl. Key words: Landau quantization, tunneling, vortex lattice. 74.50.+r; 74.60.-w; 71.70.Di; 74.20.Fg.
Milind N. Kunchur, B. I. Ivlev, D. K. Christen, and J. M. Phillips, "Vortex Instability and the Normal State of Y1Ba2Cu3O7-d at Low Temperatures." Submitted to Phys. Rev. Lett. Department of Physics and Astronomy, University of South Carolina, Columbia, SC 29208; telephone (803) 777-1907; telefax (803) 777-3065; e-mail kunchur@cosm.sc.edu; preprint available from Web site http://www.cosm.sc.edu/kunchur. 74.40.+k; 74.60.Ge; 74.72.Bk.
Takesi Kusumori and Hachizo Muto, "Fabrication of High-Quality YBCO Epitaxial Films by Ablation Using the Fourth Harmonic of the Nd:YAG Laser." To be published in Physica C (in press). Contact Hachizo Muto, Department of Chemistry, National Industrial Research Institute of Nagoya, 1 Hirate-cho, Kita-ku, Nagoya 462, JAPAN; telephone +81 52 911 2111; telefax +81 52 916 2802; e-mail hamuto@nirin.go.jp. Key words: Nd:YAG laser, YBCO epitaxial films, ablation.
M. Kusunoki, Y. Takano, M. Mukaida, and S. Ohshima, "The Influence of In-Plane 0-45 Degree Grain Boundary on Microwave Surface Resistance of c-Axis YBa2Cu3Oy Films on MgO Substrate." To be published in Physica C (in press). Department of Electrical and Information Engineering, Yamagata University, Yonezawa 992-8510, JAPAN; telefax +81 238 26 3289; e-mail kusu@eie.yz.yamagata-u.ac.jp. Key words: 0-45 degree grain boundary, surface resistance, c-axis YBa2Cu3Oy, self-template, dielectric resonator, cryocooler. 74.25.Nf; 74.76.Bz.
A. N. Lavrov, Yoichi Ando, Kouji Segawa, and J. Takeya, "Magnetoresistance in Heavily Underdoped YBa2Cu3O6+x: Antiferromagnetic Correlations and Normal-State Transport." To be publilshed in Phys. Rev. Lett. Electrical Physics Department, Komae Research Laboratory, Central Research Institute of Electric Power Industry (CRIEPI), 2-11-1 Iwado-kita, Komaeshi, Tokyo 201-8511, JAPAN; telephone +81 3 3480 2111; telefax +81 3 3480 3401; e-mail lavrov@criepi.denken.or.jp; preprint also available at http://xxx.lanl.gov/abs/cond-mat/9907051. 74.25.Fy; 74.20.Mn; 74.72.Bk.
E. J. Lee, K. B. Ma, T. L. Wilson, and W. K. Chu, "Superconductor-Magnet Bearings with Inherent Stability and Velocity-Independent Drag Torque." Preprint #99:050; submitted to the Proc. of the 1999 IEEE/ASME Int. Conf. on Adv. Intelligent Mechatronics (AIM'99), Atlanta, Ga., Sept. 19- 23, 1999. 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.
G. A. Levin and C. C. Almasan, "Conductivity of Layered Crystals." Department of Physics, Kent State University, Kent, OH 44242; e-mail levin@physics.kent.edu.
Mai Suan Li and Hikaru Kawamura, "Chiral Glass Phase in Ceramic Superconductors." Presented at the Int. Workshop on Superconductivity, Magnetoresistive Materials and Strongly Correlated Systems, Vietnam. Institute of Physics, Polish Academy of Sciences, Al. Lotnikow 32/46, PL 02-668 Warsaw, POLAND; e-mail masli@rea.ifpan.edu.pl; preprint also available at http://xxx.lanl.gov/abs/cond-mat/9907060. 75.40.Gb; 74.72.-h.
M. Machida, T. Koyama, and M. Tachiki, "Dynamical Breaking of Charge Neutrality in Intrinsic Josephson Junctions: Common Origin for Microwave Resonant Absorptions and Multiple-Branch Structures in the I-V Characteristics." Submitted to Phys. Rev. Lett. Center for Promotion of Computational Science and Engineering, Japan Atomic Energy Research Institute, 2-2-54, Nakameguro, Meguro-ku, Tokyo 153, JAPAN; telefax +81 3 5723 2537; e-mail mac@sugar.tokai.jaeri.go.jp; preprint also available at http://xxx.lanl.gov/abs/cond-mat/9907022. 74.25.Fy; 74.50.+r; 74.80.Dm.
Andrew M. Martin, Thomas Gramespacher, and Markus Buettiker, "Charge Fluctuations in a Quantum Point Contact Attached to a Superconducting Lead." Department de Physique Theorique, Universite de Geneve, CH-1211 Geneve 4, SWITZERLAND; e-mail martin@serifos.unige.ch; preprint also available at http://xxx.lanl.gov/abs/cond-mat/9907240. 72.10.Bg; 72.70.+m; 73.23.-b; 74.40.+k.
R. J. McQueeney, J. L. Sarrao, J. S. Gardner, M. F. Hundley, and R. Osborn, "Phonons and Hole Localization in La1.475Nd0.4Sr0.125CuO4." Preprint #LA-UR-99-3591. LANSCE, Lujan Center, Mail Stop H805, Los Alamos National Laboratory, Los Alamos, NM 87545; telephone (505) 665- 0841; telefax (505) 665-2676; e-mail mcqueeney@popler.lansce.lanl.gov; preprint also available at http://xxx.lanl.gov/abs/cond-mat/9907211. 74.25.Kc; 63.20.Kr; 74.20.Mn; 74.72.Dn.
Todor M. Mishonov and Mihail T. Mishonov, "Simple Model for Linear Temperature Dependence of the Electrical Resistivity of Layered Cuprates." Submitted to Physica A. Laboratorium voor Vaste-Stoffysica en Magnetisme, Katholieke Universiteit Leuven, Celestijnenlaan 200 D, B- 3001 Leuven, BELGIUM; telephone +32 16 32 7193; telefax +32 16 32 7983; e-mail todor.mishonov@fys.kuleuven.ac.be. Key words: electrical resistivity, superconductivity, perovskites. 74.25.Fy.
E. E. Mitchell, C. P. Foley, K.-H. Mueller, and K. E. Leslie, "Vortex Penetration and Hysteretic Behavior of Narrow Planar Josephson Junctions in a Magnetic Field." To be published in Physica C (in press). CSIRO Telecommunications and Industrial Physics, Bradfield Road, P.O. Box 218, Lindfield NSW 2070, AUSTRALIA; telephone +61 2 9413 7749; telefax +61 2 9413 7202; e-mail emmam@tip.csiro.au. Key words: grain boundary junctions, thin films, Abrikosov vortices, magnetic field enhancement. 74.60.Jg; 74.76.-w; 74.76.Bz; 74.80.Dm; 74.50.+r.
A. Mourachkine, "The Symmetries of the Order Parameters for Pairing and Phase Coherence in Hole-Doped Cuprates." Submitted to Physica C. Service de Physique des Solides, Universite Libre de Bruxelles, CP233, Boulevard du Triomphe, B-1050 Brussels, BELGIUM; telephone +32 2 650 5751; telefax +32 2 650 5916; e-mail anmourac@ulb.ac.be; preprint also available at http://xxx.lanl.gov/abs/cond-mat/9907182. Key words: high-Tc superconductors, order parameter, energy gap, pairing, phase coherence. 74.25.Dw; 74.72.-h.
J. Murdoch, H. Salamati, G. Quirion, and F. S. Razavi, "Magnetic and High-Pressure Studies in the YPd2B2C System." To be published in Physica C (in press). Contact F. S. Razavi, Department of Physics, Brock University, St. Catharines, Ontario, CANADA L2S 3A1; telephone (905) 688-5550; telefax (905) 682-9020; e-mail saar@newton.physics.brocku.ca. Key words: magnetic, high pressure, YPd2B2C system.
A. Nabialek, H. Szymczak, K. Piotrowski, V. Chabanenko, and Z. Pakiela, "Pinning Induced Magnetostriction in Ceramic High Temperature Superconductors." To be published in Physica C (in press). Institute of Physics, Polish Academy of Sciences, Al. Lotnikow 32/46, PL 02-668 Warsaw, POLAND; telefax +48 22 843 09 26; e-mail nabia@ifpan.edu.pl. Key words: magnetostriction, flux pinning, critical current density, weak links. 74.60.Ge; 74.60.Jg; 74.72.Bk; 74.72.Gr; 74.50.+r.
Naoto Nagaosa and Patrick A. Lee, "Confinement and Bose Condensation in Gauge Theory of High-Tc Superconductors." Department of Applied Physics, University of Tokyo, Bunkyo-ku, Tokyo 113, JAPAN; e-mail nagaosa@appi.t.u-tokyo.ac.jp; preprint also available at http://xxx.lanl.gov/abs/cond-mat/9907019.
A. V. Nikulov, E. Milani, G. Balestrino, and V. A. Oboznov, "Comparison of the Fluctuation Influence on the Resistive Properties of the Mixed State of Bi2Sr2CaCu2O8+x and of Thin Films of Conventional Superconductors." To be published in Supercond. Sci. & Technol. Institute of Microelectronics Technology and High Purity Materials, Russian Academy of Sciences, 142432 Chernogolovka, Moscow District, RUSSIA; telephone +7 095 962 8074; telefax +7 095 962 8047; e-mail nikulov@ipmt-hpm.ac.ru; preprint also available at http://xxx.lanl.gov/abs/cond-mat/9905098.
Matthias Opel, Martin Goetzinger, Christian Hoffmann, Ralf Nemetschek, Richard Philipp, Francesca Venturini, Rudi Hackl, Andreas Erb, and Eric Walker, "Pseudogap and Superconducting Gap in YBa2Cu3O6+x: A Raman Study." To be published in J. Low Temp. Phys.: Proc. of the Int. Conf. on Phys. and Chem. of Molecular and Oxide Supercond. (MOS'99), Stockholm, Sweden, July 28-Aug. 2, 1999. Walther-Meissner-Institut fuer Tieftemperaturforschung, Bayerischen Akademie der Wissenschaften, Walther-Meissner-Strasse 8, D-85748 Garching, GERMANY; telephone +49 89 289 14237; telefax +49 89 289 14206; e-mail opel@badw.de or matthias.opel@lrz.badw-muenchen.de; preprint also available at http://xxx.lanl.gov/abs/cond-mat/9906446. 74.25.Jb; 74.72.Bk; 78.20.Bh; 78.30.Er.
Matthias Opel, Francesca Venturini, Rudi Hackl, Helmuth Berger, and Laszlo Forro, "Superconducting Gap and Pseudogap in Bi-2212." To be published in Physica B: Proc. of the 22nd Int. Conf. on Low Temp. Phys. (LT22), Helsinki, Finland, Aug. 5-11, 1999. Walther-Meissner-Institut fuer Tieftemperaturforschung, Bayerischen Akademie der Wissenschaften, Walther-Meissner-Strasse 8, D-85748 Garching, GERMANY; telephone +49 89 289 14237; telefax +49 89 289 14206; e-mail opel@badw.de or matthias.opel@lrz.badw-muenchen.de; preprint also available at http://xxx.lanl.gov/abs/cond-mat/9906448. Key words: Raman scattering, Bi2Sr2CaCu2O8+d, superconducting gap, pseudogap.
J. Oppenlaender, Ch. Haeussler, and N. Schopohl, "Dynamic Electromagnetic Response of Three-Dimensional Josephson Junction Arrays." Submitted to J. Appl. Phys. Institut fuer Theoretische Physik, Universitaet Tuebingen, Auf der Morgenstelle 14, D-72076 Tuebingen, GERMANY; e-mail joerg.oppenlaender@uni-tuebingen.de; preprint also available at http://xxx.lanl.gov/abs/cond-mat/9907105.
Aaron A. Pesetski and Thomas R. Lemberger, "Experimental Study of the Inductance of Pinned Vortices in Superconducting YBa2Cu3O7-d Films." Submitted to Phys. Rev. B. Department of Physics, Ohio State University, Columbus, OH 43210-1106; Thomas R. Lemberger's telephone (614) 292-7799; e-mail trl@mps.ohio-state.edu; preprint also available at http://xxx.lanl.gov/abs/cond-mat/9907039. 74.60.Ge; 74.40.+k; 74.25.Nf; 74.62.Dh.
T. Plackowski and M. Matusiak, "Normal State Ettingshausen Effect in La2-xSrxCuO4." To be published in Supercond. Sci. & Technol. Institute of Low Temperature and Structure Research, Polish Academy of Sciences, P.O. Box 1410, 50-950 Wroclaw 2, POLAND; telephone +48 71 3435021, ext. 278; telefax +48 71 441029; e-mail t.plackowski@int.pan.wroc.pl; preprint also available at http://xxx.lanl.gov/abs/cond-mat/9904340.
S. Plibersek and P. F. Meier, "Interpretation of Nuclear Quadrupole Resonance Spectra in Doped La2CuO4." Physics Institute, University of Zurich, CH-8057 Zurich, SWITZERLAND; P. F. Meier's e-mail pfmeier@physik.unizh.ch; preprint also available at http://xxx.lanl.gov/abs/cond-mat/9907349.
M. Podt, D. Keizer, J. Flokstra, and H. Rogalla, "Digital SQUIDs Based on Smart DROS." To be published in Physica C (in press). Low Temperature Division, Department of Applied Physics, University of Twente, P.O. Box 217, 7500 AE Enschede, THE NETHERLANDS; telephone +31 53 489 3141; telefax +31 53 489 1099; e-mail m.podt@tn.utwente.nl. Key words: superconducting device, SQUID, relaxation oscillations, Josephson electronics. 85.25.Am; 85.25.Dq; 85.25.Na.
M. Potthoff and W. Nolting, "Metallic Surface of a Mott Insulator: Mott Insulating Surface of a Metal." To be published in Phys. Rev. B. (in press). Institut fuer Physik, Humboldt-Universitaet zu Berlin, D-10115 Berlin, GERMANY; e-mail potthoff@physik.hu-berlin.de; preprint also available at http://xxx.lanl.gov/abs/cond-mat/9906412. 71.10.Fd; 71.30.+h; 73.90.+f.
T. Prikhna, W. Gawalek, V. Moshchil, R. Viznichenko, F. Sandiumenge, V. Melnikov, P. Shaetzle, P. Nagorny, A. Surzhenko, S. Dub, and Ch. Wende, "Thermobaric Effect on Melt-Textured MBa2Cu3O7-d (M=Y,Nd)." Submitted to Physica B: Proc. of the 22nd Int. Conf. on Low Temp. Phys. (LT22), Helsinki, Finland, Aug. 5-11, 1999. Institute for Superhard Materials, 2 Avtozavodskaya Str., Kiev 254074, UKRAINE; e-mail frd@ismanu.kiev.ua; preprint also available at http://xxx.lanl.gov/abs/cond-mat/9907054. Key words: high-temperature superconductors, melt-textured MBa2Cu3O7-d, critical current density, high pressure, thermobaric treatment.
J. E. Rodriguez and A. Marino, "Thermodynamic Fluctuations in Silver Doped BSCCO Superconducting System." To be published in Phys. Rev. B. Department of Physics, Universidad Nacional de Colombia, A.A. 85814, Bogota, COLOMBIA; e-mail jerodrig@ciencias.ciencias.unal.edu.co. 74.25.Fy; 74.40.+k.
J. Roehler, "Plane Dimpling and Cu 4s Hybridization in YBa2Cu3Ox." Submitted to Physica B: Proc. of the 22nd Int. Conf. on Low Temp. Phys. (LT22), Helsinki, Finland, Aug. 5-11, 1999. II. Physikalisches Institut, Universitaet zu Koeln, Zuelpicherstr. 77, D-50937 Koeln, GERMANY; e-mail abb12@uni-koeln.de; preprint also available at http://xxx.lanl.gov/abs/cond-mat/9906432. Key words: electronic structure, superconductivity, YBa2Cu3O7, EXAFS.
B. Ruck, Y. Chong, R. Dittmann, and M. Siegel, "First Order Sigma-Delta Modulator in HTS Bicrystal Technology." To be published in Physica C (in press). Contact M. Siegel, Institut fuer Schicht- und Ionentechnik (ISI), Forschungszentrum Juelich, D-52425 Juelich, GERMANY; e-mail m.siegel@fz-juelich.de. Key words: sigma-delta modulator, balanced comparator, multilayer technology, bicrystal junction.
F. Schaefer, C. Timm, D. Manske, and K. H. Bennemann, "Theory for Underdoped High-Tc Superconductors: Effects of Phase Fluctuations." Submitted to the Proc. of the Int. Conf. on Phys. and Chem. of Molecular and Oxide Supercond. (MOS'99), Stockholm, Sweden, July 28-Aug. 2, 1999. Institut fuer Theoretische Physik, Freie Universitaet Berlin, Arnimallee 14, D-14195 Berlin, GERMANY; e-mail schaefer@physik.fu-berlin.de; preprint also available at http://xxx.lanl.gov/abs/cond-mat/9907345. 74.72.-h; 74.20.Mn; 74.25.Jb.
C. W. Schneider, R. R. Schulz, B. Goetz, A. Schmehl, H. Bielefeldt, H. Hilgenkamp, and J. Mannhart, "Tailoring of High-Tc Josephson Junctions by Doping Their Electrodes." Submitted to Appl. Phys. Lett. Experimentalphysik VI, Center for Electronic Correlations and Magnetism, Institute of Physics, University of Augsburg, Universitaetsstr. 1, D- 86135 Augsburg, GERMANY; telephone +49 821 598 3659; telefax +49 821 598 3652; e-mail christof.schneider@physik.uni-augsburg.de. Key words: high-temperature superconductivity, critical current density, grain boundaries, Josephson junctions. 74.72.Bk; 74.60.Jg; 74.50.+r.
G. Seibold and S. Varlamov, "Relationship Between Incommensurability and Superconductivity in Peierls Distorted Charge-Density-Wave Systems." Submitted to Phys. Rev. B. Lehrstuhl fuer Theoretische Physik, Brandenburgische Technische Universitaet Cottbus, Postfach 101344, D- 03013 Cottbus, GERMANY; telephone +49 355 693-006 or -010; telefax +49 355 693-011; e-mail goetz@physik.tu-cottbus.de; preprint also available at http://xxx.lanl.gov/abs/cond-mat/9907030. 74.20.Fg; 74.25.-q; 74.25.Kc; 74.72.Dn.
D. V. Sheptyakov, V. Yu. Pomjakushin, A. M. Balagurov, A. A. Zakharov, C. Chaillout-Bougerol, and G. J. McIntyre, "Structure of Non-Phase- Separated La2CuO4.03 Studied by Single-Crystal Neutron Diffraction." To be published in Physica C (in press). Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research, 141980 Dubna, Moscow Region, RUSSIA; telephone +7 09621 62690; telefax +7 09621 65882; e-mail shden@nf.jinr.ru. Key words: phase separation, La-based cuprates, neutron diffraction. 74.72.Dn; 61.12.Ld.
J.M.S. Skakle and A. R. West, "Crystal Structure-Tc Correlations in LaBa1.5Ca0.5Cu3Od." To be published in Physica C (in press). Department of Chemistry, University of Aberdeen, Meston Walk, Aberdeen AB24 3UE, UNITED KINGDOM; telephone +44 1224 273 798; telefax +44 1224 272 921; e-mail j.skakle@abdn.ac.uk. Key words: neutron diffraction, Rietveld refinement, Cu-O bond lengths, critical temperature. 74.62.Bf; 74.72.Jt; 61.12.Gz; 81.40.Rs.
E. Y. Sun, A. Goyal, D. P. Norton, C. Park, D. M. Kroeger, M. Paranthaman, and D. K. Christen, "High-Resolution Transmission Electron Microscopy/Analytical Electron Microscopy Characterization of Epitaxial Oxide Multilayers Fabricated by Laser Ablation on Biaxially Textured Ni." To be published in Physica C (in press). Contact A. Goyal, Metals and Ceramics Division, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN 37831-6068; telephone (423) 574-1587; telefax (423) 574-7659; e-mail zag@ornl.gov. Key words: TEM, AEM, laser ablation.
R. Surdeanu, R. J. Wijngaarden, E. Visser, J. M. Huijbregtse, J. H. Rector, B. Dam, and R. Griessen, "Kinetic Roughening of Penetrating Flux Fronts in High-Tc Thin Film Superconductors." To be published in Phys. Rev. Lett. Department of Physics and Astronomy, Faculty of Sciences, Vrije Universiteit, De Boelelaan 1081, 1081 HV Amsterdam, THE NETHERLANDS; telephone +31 20 444-7923; telefax +31 20 444-7991 or -7899; e-mail radu@nat.vu.nl.
F. Tafuri, F. Miletto Granozio, F. Carillo, F. Lombardi, U. Scotti Di Uccio, K. Verbist, O. Lebedev, and G. Van Tendeloo, "Josephson Phenomenology and Microstructure of YBaCuO Artificial Grain Boundaries Characterized by Misalignment of the c Axes." To be published in Physica C (in press). INFM-Dipartimento di Scienze Fisiche, Universita di Napoli "Federico II," Piazzale Tecchio 80, I-80125 Napoli, ITALY; telephone +39 081 76 82 584; telefax +39 081 23 91 1821; e-mail tafuri@axpna1.na.infn.it. Key words: Josephson phenomenology, microstructure, YBaCuO. 74.50.+r; 74.72.Bk; 74.76.Bz; 74.80.Fp.
K. Tanaka and F. Marsiglio, "Electronic Shell Structure of Nanoscale Superconductors." Report #Alberta Thy 06-99. Department of Physics, University of Alberta, Edmonton, Alberta, CANADA T6G 2J1; e-mail ktanaka@phys.ualberta.ca; preprint also available at http://xxx.lanl.gov/abs/cond-mat/9907183. 74.20.Fg; 71.24.+q; 71.10.Fd; 71.10.Li.
Masanori Tsuchimoto, Kikyotaka Matsuura, Norio Homma, and Mizushi Matsuda, "Evaluation of Motion of a High-Tc Superconducting Thin Film in Microgravity Experiments." To be published in Physica C (in press). Electrical Engineering, Hokkaido Institute of Technology, 7-15 Maeda, Teine-ku, Sapporo 006-8585, JAPAN; telephone +81 11 681 2161; telefax +81 11 681 3622; e-mail tsuchi@em-si.eng.hokudai.ac.jp. Key words: high-Tc superconductor, thin film, microgravity, frozen field model, macroscopic numerical simulation.
J. G. Wen, T. Satoh, M. Hidaka, S. Tahara, N. Koshizuka, and S. Tanaka, "Atomic Structure and Composition of the Barrier in the Modified Interface High-Tc Josephson Junction Studied by Transmission Electron Microscopy." Submitted to Appl. Phys. Lett. Superconductivity Research Laboratory, International Superconductivity Technology Center (ISTEC), 10-13 Shinonome 1-chome, Koto-ku, Tokyo 135-0062, JAPAN; telephone +81 3 3536 5707; telefax +81 3 3536 5705; e-mail jgwen@istec.or.jp.
R. Wortis, A. J. Berlinsky, and C. Kallin, "Spin-Lattice Relaxation in the Mixed State of YBa2Cu3O7-d: Can We See Doppler-Shifted d-Wave Quasiparticles?" Department of Physics and Astronomy, McMaster University, 1280 Main Street West, Hamilton, Ontario, CANADA L8S 4M1; e- mail wortis@ivy.physics.mcmaster.ca; preprint also available at http://xxx.lanl.gov/abs/cond-mat/9907093.
Chien-Jang Wu, "Angular Dependence of Microwave Transmission and Reflection of Type-II Superconducting Film in the Mixed State." To be published in Physica C (in press). Department of Electro-Optics Engineering, National Huwei Institute of Technology, Huwei, Yunlin 63208, TAIWAN. Key words: microwave, mixed state, multilayers, penetration depth. 74.25.Nf; 74.60.Ge; 74.76.Bz.
Ke-xi Xu, Abbas A. Essa, and Jia-shan Bao, "Non-Ohmic Dissipation in Granular YBCO Films with Microwave Radiation." To be published in Physica C (in press). Department of Physics, Shanghai University, Shanghai 201800, PEOPLE'S REPUBLIC OF CHINA. Key words: granular superconductivity, microwave absorption, K-T transition.
Youichi Yanase and Kosaku Yamada, "Theory of Pseudogap Phenomena in High-Tc Cuprates Based on the Strong Coupling Superconductivity." To be published in J. Phys. Soc. Jpn. Department of Physics, Kyoto University, Kyoto 606-8502, JAPAN; e-mail yanase@ton.scphys.kyoto- u.ac.jp; preprint also available at http://xxx.lanl.gov/abs/cond- mat/9906418. Key words: high-Tc cuprates, pseudogap phenomena, strong coupling superconductivity, superconducting fluctuation, weakly damped pre-formed pair, resonance.
L. You and M. Marinescu, "Prospects for p-Wave Paired BCS States of Fermionic Atoms." School of Physics, Georgia Institute of Technology, Atlanta, GA 30332-0430; e-mail ly14@prism.gatech.edu; preprint also available at http://xxx.lanl.gov/abs/cond-mat/9906250. 03.75.Fi; 67.40.-w; 32.80.Pj; 42.50.Vk.
August Yurgens, Dag Winkler, Tord Claeson, Seong-Ju Hwang, and Jin-Ho Choy, "Pseudogap Features of Intrinsic Tunneling in (HgBr2)-Bi2212 Single Crystals." Presented at the Second Int. Conf. on New Theories, Discoveries and Applications of Superconductors and Related Materials (New3SC-2), Las Vegas, Nev., May 31-June 4, 1999; to be published in Int. J. Mod. Phys. B. Department of Microelectronics and Nanoscience, Chalmers University of Technology and Goeteborg University, S-41296 Goeteborg, SWEDEN; e-mail yurgens@fy.chalmers.se; preprint also available at http://xxx.lanl.gov/abs/cond-mat/9907159.
P. Zhang, C. Ren, S. Y. Ding, F. Y. Lin, Z. M. Li, S. A. Aruna, L. Qiu, X. X. Yao, and G. D. Gu, "Dip Effect in chi' of ac Susceptibility in Bi2Sr2CaCu2Od Single Crystal." To be published in Physica C (in press). Contact S. Y. Ding, Department of Physics and National Laboratory of Solid State Microstructures, Center for Advanced Studies in Science and Technology of Microstructures, Nanjing University, Nanjing 210093, PEOPLE'S REPUBLIC OF CHINA; telefax +86 25 330 2728; e-mail syding@nju.edu.cn. Key words: dip effect, ac susceptibility, Bi2Sr2CaCu2Od single crystal. 74.60.Ge; 74.72.Bk.
X. G. Zheng, N. Tsutsumi, S. Tanaka, M. Suzuki, and C. N. Xu, "Electric and Magnetic Anomaly in Single Crystalline CuO." To be published in Physica C (in press). Department of Physics, Saga University, Saga 840- 8502, JAPAN; telefax +81 952 28 8547; e-mail zheng@cc.saga-u.ac.jp. Key words: cupric oxide, transport phenomena, electronic anomaly, strong correlation. 72.20.-i; 72.80.Jc; 75.30.-m.
COMING EVENTS (An * indicates a previously listed event. Also see complete listing of upcoming conferences and workshops at our Web site http://www.iitap.iastate.edu/htcu/comevents.html.)
*Feb. 20 - Feb. 25, 2000: Sixth International Conference on Materials and Mechanisms of Superconductivity and High Temperature Superconductors (M^2S-HTSC-VI), George R. Brown Convention Center, Houston, Texas. Hosted by the Texas Center for Superconductivity at the University of Houston and sponsored by federal agencies and industry. Co-Chairs: C. W. Chu, W. K. Chu, and K. Salama. This series of meetings, established in 1988 two years after the discovery of high-temperature superconductors, is dedicated to superconductivity and related phenomena, and the host materials of these phenomena. The Conference will bring together members of the international low- and high- temperature superconductivity community to focus on recent insights into low- and high-temperature superconductor physics, materials, and devices. Emerging areas and future trends will also be highlighted. General conference topics include, but are not limited to, experimental and theoretical studies of Superconducting Materials -- low temperature, high temperature, fullerite, heavy fermion, organic, new; Physical Properties -- mechanisms, magnetic, electrical, optical, thermal, mechanical, acoustic; Synthesis and Processing -- thin films, superlattices, thick films, bulk; and Applications -- small current (SQUIDs, junctions, microwave devices) and large current (cables, transformers, motors, generators, magnetic levitation devices). Abstract deadline, September 15, 1999. For information, contact M^2S- HTSC-VI Conference Secretariat, Texas Center for Superconductivity, University of Houston, 3201 Cullen Boulevard, Houston, TX 77204-5932; telefax (713) 743-8216; Web site http://m2s-conf.uh.edu.
*March 31 - April 10, 2000: Conference on Major Trends in Superconductivity in the New Millennium (MTSC 2000) and Symposium on Itinerant and Localized States in HTSC (SILS), Klosters, Kanton Graubuenden, Switzerland. Scope of MTSC 2000 is on recent developments and trends in new superconducting systems with emphasis on experiments and theories which are relevant to the pairing mechanism. Besides the superconducting cuprates, conventional superconductors, organic systems, borocarbides, ruthenates, nanostructures, and fullerenes will be addressed. In order to raise the awareness for novel ideas and results in this rapidly growing field, the physics and chemistry of related materials will be included. Special emphasis on phenomena related to nanoscale phase separation and charge modulation. Symposium on Itinerant and Localized States in HTSC (SILS) will focus on large and small polaron and bipolaron effects in high-Tc materials with special emphasis on their preparative properties. MTSC 2000 is organized in close analogy to the Gordon conferences. Limited number of slots for posters. Total number of participants limited to 130 persons. Proceedings will be published in a special issue of Journal of Superconductivity. Abstract and pre-registration deadline, November 15, 1999. For more information, contact Annette Bussmann-Holder, Max- Planck-Institut fuer Festkoerperforschung, Heisenbergstr. 1, D-70569 Stuttgart, Germany; telephone +49 711 689 1679; telefax +49 711 689 1091. Or contact Vladimir Z. Kresin, Lawrence Berkeley Laboratory, University of California, 1 Cyclotron Road, Berkeley CA 94720; telephone (510) 486-6951; telefax (510) 486-5401. Information also available at Web site http://www.mpi-stuttgart.mpg.de/CONF/mtsc2000.html.
April 24 - 28, 2000: Superconducting and Related Oxides -- Physics and Nanoengineering IV, Marriott's Orlando World Center Resort and Convention Center, Orlando, Fla. Part of SPIE's 2000 AeroSense Symposium. Fourth in the series of SPIE conferences focused on basic issues in physics and materials science of high-temperature superconductors and related compounds that may be relevant for their applications in electronics, optics, and optoelectronics. Original papers are solicited on, but not limited to, the following topics: a) structural, transport, magnetic, and thermal properties of thin films of cuprates and related compounds; b) homoepitaxy, new substrate materials, epitaxial and morphological properties, interface smoothness and disorder, layer thickness fluctuations, interdiffusion, and strain; c) proximity effects, surface and interface effects, and superconductors in contact with insulators, semiconductors, normal metals, ferro- and antiferromagnets, piezoelectrics, etc.; d) search for novel high- temperature superconducting phases by atomic engineering; e) electronic structure, charge redistribution, localization, single-particle and collective excitations, and Josephson phenomena in natural and artificial superlattices; f) novel device concepts, electric field effect in heterostructures, hybrid optoelectronic devices, and cryoelectronics. Abstract deadline, September 27, 1999 (submission via Web site strongly encouraged). Three-day exhibition. Proceedings to be published. To receive a complete call for papers by postal mail or to request an Advance Technical Program, contact SPIE, P.O. Box 10, Bellingham, WA 98227-0010; telephone (360) 676-3290; telefax (360) 647- 1445; e-mail OR@spie.org; Web site http://www.spie.org/web/meetings/calls/or00/confs/OR15.html.
Sept. 17 - 22, 2000: Applied Superconductivity Conference, Pavilion Convention Center, Virginia Beach, Va. Abstract deadline, February 11, 2000. More details will follow on Web site http://www.ascinc.org/.
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Position Open: A research position in electron microscopy of oxides is available at Oxxel GmbH, instituted on the campus of the University of Bremen, Germany. Will primarily be responsible for monitoring and study of film surfaces by low-energy electron microscopy and diffraction (LEEM, LEED), in situ and in real-time during atomic-layer-by-layer molecular beam epitaxy (ALL-MBE) growth. An ideal candidate will have a Ph.D. from a leading school in crystallography, materials science, or solid-state physics, as well as extensive experience with electron microscopy. Candidates should send CV and other relevant material to Dr. Ivan Bozovic, Oxxel GmbH, Technologiepark Universitaet, Fahrenheitstrasse 9, D-28359 Bremen, GERMANY; telephone +49 421 2046 6310; telefax +49 421 2046 6350; e-mail info@oxxel.de.
Position Open: A research position is available to explore the feasibility of ion-damaged high-Tc superconductors as manufacturable Josephson junctions. Work will be in collaboration with Northrup Grumman and will investigate the reproducibility and uniformity of ion- damaged junctions. Starting date will be as soon as possible. Position may be for a postdoctoral, visitor, or sabbatical status. For information, contact Professor Robert C. Dynes, University of California at San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0319; telephone (858) 534-5924; telefax (858) 534-2232; e-mail rcd@physics.ucsd.edu.
Donations of books, journals, conference proceedings, etc., are requested for newly established institute of physics in India. Please contact Dr. S. L. Kakani, Shastrinagar Extension, Bhilwara 311001 (RAJ), India; telephone +91 1482 52071; telefax +91 1482 20096; e-mail shyamznwar@usa.net.
High-Tc Update is the high-Tc superconductivity information exchange newsletter. Please send 1) preprints, reprints, and other research reports; 2) descriptions of on-going work; 3) meeting announcements and summaries.
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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. 13, #16, August 15, 1999.