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, NSF, and other agencies, organizations, and individuals.

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NOTA BENE:

Theory

The pseudogap onset temperature T*, the superconducting transition temperature Tc, and the general nature of the pseudogap phase have been investigated by J. Maly et al. (Chicago) using a diagrammatic BCS - Bose-Einstein crossover theory based on the pairing approximation of Kadanoff and Martin, further extended by Patton (KMP). When the coupling constant g of the theory is varied from small to large, the system is found to cross over from BCS to Bose-Einstein behavior. The authors' Tc equations reveal a rich structure as a function of g, in which the pseudogap is found to compete with superconductivity. The authors compare their results with those of alternate theories in the literature.

Other consequences of the above theory are described by I. Kosztin et al. (Chicago). In this paper, the authors investigate how the pseudogap evolves into its below-Tc counterpart. The authors find an important distinction between the superconducting excitation gap and the order parameter. Further consequences are discussed in a related paper by Q. Chen et al. (Chicago).

A theory for the doped antiferromagnet based on the bosonic resonating- valence-bond (RVB) description incorporating the phase string effect has been proposed by Z. Y. Weng et al. (TCSUH). Both antiferromagnetic (AF) and superconducting phase transitions occur naturally inside such a bosonic RVB phase. Two distinct metallic regions - underdoping and optimum-doping - are also found to be a logical consequence, whose features explain some recent neutron-scattering measurements in cuprates.

A preprint by R. A. Klemm (Argonne) et al. reports a calculation of I_c(T) and R_n for both coherent and incoherent electron tunneling across a c-axis break junction between two s- or two d_[x^2-y^2]-wave layered superconducting half spaces, each with c-axis bandwidth 2J. The authors find that coherent quasiparticle tunneling occurs only for voltages V < 2J/e, leading to difficulties in measuring R_n for underdoped samples. The coherent part of I_c(0) is independent of Delta(0) for J/Delta(0) << 1, and can be large. The authors discuss their results with regard to recent experiments.

Using the linearized gap equation and a microscopic theory, W. K. Kim et al. (TCSUH) have calculated the upper critical field H_[c2] of a mixed d- and s-wave superconductor from Tc down to zero temperature. Near Tc, H_[c2] is found to increase almost linearly with decreasing temperature. Moreover, over the entire temperature region the mixed d- and s-wave superconductor has a larger value of H_[c2] than that of a pure d-wave superconductor. The authors also find that H_[c2] vs. T has negative curvature, indicating that an admixture of the s-wave component cannot be the origin of the upward curvature that has been reported in some experiments and some calculations based on the Ginzburg-Landau equations.

As pointed out by A. I. Buzdin (Bordeaux) and A. A. Varlamov (Firenze and Moscow Institute for Steel and Alloys), a fit of the experimental data on the c-axis magnetoresistance of high-temperature superconductors above Tc with the theory based on fluctuation renormalization of the one-electron density of states is excellent in weak magnetic fields but meets with difficulties at high fields because of divergences in the theory. The authors propose a scheme to regularize this problem, and they calculate analytically the asymptotics for all regions of magnetic fields.

A preprint by H. J. Kaufmann (Cambridge) et al. compares observed optical reflectivity in the infrared spectral region with theoretical predictions in a strongly coupled electron-phonon system. The authors find that the normal-state optical spectra of both YBa2Cu3O7-d and La2- xSrxCuO4 can be well accounted for over a wide frequency range and that systematic differences exist only in the mid-infrared region. The authors suggest that a detailed model for the optical response should include temperature-dependent mid-infrared bands.

An ordered excitonic phase that develops around an electronic topological transition in a 2D electron system on a square lattice is studied by M. Kiselev (Saclay and Kurchatov Institute) et al. The authors point out features of their theory that resemble corresponding features seen via angle-resolved photoemission spectroscopy (ARPES) in the normal state of the underdoped hole-doped cuprates.

A preprint by R. M. Quick and S. G. Sharapov (Pretoria) studies the Coleman-Weinberg effective potential in the theory of superconductivity. The authors conclude that the appearance of an imaginary part in the one-loop effective potential does not signal the onset of superconductivity but instead reflects a failure of the one-loop approximation.

Vortices

The electromagnetic response of a pancake vortex in a layered superconductor has been calculated by M. Eschrig (Bayreuth) using the quasiclassical theory of superconductivity. The author considered relatively clean s-wave superconductors, with a mean free path l larger than the coherence length xi_0, at frequencies of the order of the gap frequency. The current response was found to be dominated by the bound states of Caroli, de Gennes, and Matricon and to differ significantly from the response obtained from the model of the normal core introduced by Bardeen and Stephen. The latter model describes the limit of a dirty core (l << xi_0) but fails for a clean superconductor. The response of the bound states includes nondissipative acceleration of the charge carriers as well as dissipative currents.

Small-angle neutron diffraction has been used by A. Vostner (Atominstitut-Wien) et al. to image the vortex lattice in a large superconducting La2-xSrxCuO4 (LSCO) single crystal. The authors obtained diffraction patterns in fields up to 0.2 T and at several temperatures (3-26 K). Instead of diffraction peaks, however, the authors found an intensity ring, indicating a polycrystalline vortex lattice in this material. The authors relate this observation to a structural phase transition at ~200 K, which destroys the single- crystalline character of the sample because of uncontrolled twinning.

An analysis of magnetization and entropy jumps in the mixed state of high-temperature superconductors has been carried out by A.I.M. Rae (Birmingham) et al. The authors note, for example, that the Clausius- Clapeyron relationship between the magnetization jump and the entropy jump involves the local H field, not the B field or the applied magnetic field. The authors present and analyze new experimental data on local field jumps and global magnetization measurements in Bi2Sr2CaCu2O8+d (Bi-2212). The authors find that the data are consistent with the boundary between the vortex liquid and solid phases having a width of around 20 flux-line spacings at a field of 10 mT.

As shown by B. Khaykovich (Weizmann Institute and Ecole Polytechnique- Palaiseau) et al., the first-order transition of the vortex lattice in Bi2Sr2CaCu2O8+d (Bi-2212) crystals transforms into a continuous transition when disorder is introduced via a very low concentration of columnar defects. The authors demonstrate fine tuning of the disorder strength and recovery of the first-order transition by varying the concentration of the columns, changing the temperature along the melting line, or tilting the magnetic field with respect to the columns.

A phenomenological model for melting of a vortex lattice, based on screening of the elastic shear modulus by mobile or partially pinned dislocations, is proposed in a preprint by D. Feinberg (CNRS-Grenoble). The author finds a first-order softening line, ending at a critical point beyond which the lattice crosses over to a hexatic vortex solid. The author points out several consequences of softening on vortex dynamics, which should serve as fingerprints of the plastic dynamics.

Simulations of the first-order phase transition in YBa2Cu3O7-d have been carried out by A. K. Kienappel and M. A. Moore (Manchester) using the Lawrence-Doniach model. The authors find that the magnetization discontinuity vanishes and the first-order transition line ends at a critical end point for low magnetic fields in agreement with experiment. The authors assert that the transition is not associated with vortex- lattice melting, but separates two vortex-liquid states characterized by different degrees of short-range crystalline order and different length scales of correlations between vortices in different layers.

A variational approach for calculating the magnetization of a high-kappa type-II superconductor for the entire range of fields H_[c1] <= H_0 <= H_[c2] is given in a preprint by O. N. Shevtsova and S. V. Shijanovskii (Kiev). The vortex structure is described using a circular-cell London model and a trial order parameter in the form of a constant for rho >= rho_m and this constant times sin(pi[rho]/2rho_m) for rho <= rho_m, where rho_m is the core radius. The results are in good agreement with recent numerical calculations using the full Ginzburg-Landau equations.

Force-free configurations of vortices in the line-liquid and line- crystal limits near the upper critical field H_[c2] have been studied theoretically by R. D. Kamien (Pennsylvania). The author finds that the condition for force-free configurations (j || B) can be solved by appealing to the structure of chiral liquid crystalline phases.

The peak effect in a single-crystal sample consisting of a Nb-O solid solution has been studied by Y. Kopelevich and S. Moehlecke (Unicamp) using magnetization measurements. The effect is understood as a disorder-driven transition (or crossover) between a relatively ordered vortex lattice and an entangled vortex state. The authors found that the characteristic relaxation process in the peak-effect region is a large magnetization jump occurring at a jump time t_j(H,T) that quasi- diverges at the peak field H_p(T).

Measurements of the surface impedance of thick samples of PbIn10.5wt%, PbIn5wt%, and V in the mixed state over the frequency range 2 kHz - 20 MHz have been carried out by N. Luetke-Entrup et al. (Ecole Normale Superieure). The authors observe the depinning crossover but find it to be much broader than expected from classical theories of pinning, and they also observe size effects. A description of vortex dynamics involving surface pinning and free vortex flow in the bulk is found to account for the complex apparent penetration depth.

Flux Penetration

An experimental technique for simultaneous measurement of both the normal (B_z) and in-plane (B_x) components of the magnetic induction field B near the surface of a superconducting sample is described in a preprint by Y. Abulafia (Bar-Ilan) et al. This technique makes use of a double-layered Hall sensor array fabricated from a GaAs/AlGaAs heterostructure containing two parallel layers of a two-dimensional electron gas (2DEG). The new aspect of this sensor is that measurements of B_z at the same x but at different heights z above the surface (separated by a distance ~1 micrometer) yield, with the help of grad[dot]B = 0, del[B_z]/del[z] = -del[B_x]/del[x]. Thus, B_x(x,0) at the sample surface (z = 0) can be obtained by integration of the experimentally determined values of del[B_x]/del[x]. The effectiveness of the technique is demonstrated in measurements of B_x and B_z and the corresponding current distribution at the surface of a thin YBa2Cu3O7-d crystal.

The dynamics of magnetic flux penetration (vortices) into a superconductor containing magnetic flux of the opposite sign (antivortices) has been considered by F. Bass (Bar-Ilan) et al. The authors find that the width of the region where vortices and antivortices coexist is typically large, of order a_0^2/xi >> a_0, where a_0 is the intervortex distance and xi is the linear dimension of the vortex-antivortex annihilation cross section. The authors note that the local temperature rises to a maximum in the annihilation region, and that an overheating instability may propagate when the annihilation rate reaches a critical value.

The magnetic flux distribution across a current-carrying high- temperature superconducting strip has been measured by M. E. Gaevski (St. Petersburg) et al. using magneto-optical imaging at 15 K. The results were compared with predictions of the Bean model for the thin- strip geometry, and reasonable agreement was found. However, much better agreement was achieved using numerical calculations accounting for flux creep.

The mixed state of several RBa2Cu3O7-d (R = Y, Yb) single crystals has been investigated by M. Werner (Atominstitut-Wien) et al. using various measuring techniques. Using an 8 T SQUID magnetometer as a reference, the authors compared the current densities evaluated from global magnetization measurements (SQUID, torque, and VSM) and from a local technique (Hall-probe array). Taking the specific time scales of the various measurements into consideration, the authors found excellent agreement at all temperatures in the range 5-77 K. Magneto-optical images of the flux-density gradients also confirmed that the current densities can be calculated using an extended Bean model.

Isothermal magnetization (M) versus magnetic field (H) curves, coupled with the critical state model, are routinely used to extract the critical current density Jc(B). The same hysteretic M-H curves also can be used to estimate the equilibrium magnetization M_[eq](H), and a preprint by P. Chaddah et al. (Indore) discusses the validity of such a procedure using analytically tractable models for Jc(H). The authors put special emphasis on the case where M vs. H shows a fish-tail or peak effect, and they present an experimental procedure to estimate errors in the estimated M_[eq](H).

RBa2Cu3O7-d

Oxygen diffusion in undoped and silver-doped YBa2Cu3O7-d (YBCO) single crystals has been investigated by D. K. Aswal et al. (BARC-Mumbai) using isothermal resistivity measurements in the temperature interval 550- 750^oC. The authors found that the diffusion coefficients for silver- doped crystals were an order of magnitude lower than those for undoped crystals. Moreover, the activation energy for oxygen diffusion was found to be considerably higher for Ag-doped crystals. The authors conclude that silver doping stabilizes the YBCO phase with higher oxygen content.

The growth of a YBCO single crystal from a sharpened YBCO seed crystal is described in a preprint by T. Kusao et al. (SRL-ISTEC). A modified pulling method was used to grow a crystal of size 13 mm x 13 mm x 10 mm.

An interpretation of Tc suppression in Y1-xPrxBa2Cu3O7-d is presented by G. Cao et al. (Zhejiang). The explanation involves a combination of (a) partial hole transfer from the pd sigma band to the p-f hybridization band and (b) magnetic scattering effects. The hole density that resides in the pd sigma band decides T_[co](x) by the phenomenological inverted parabolic relation, while magnetic scattering further lowers Tc according to pair-breaking theory.

The suppression of superconductivity by Pr dopants in Y1-xPrxBa2Cu3O7-d is considered in a preprint by V. A. Voloshin (Donetsk) et al. The authors argue that magnetic pair breaking and localization of charge carriers do not provide a satisfactory description, and they propose a possible explanation in terms of a Pr-O resonance involving a vibronic state.

A paper by M. Muroi and R. Street (Western Australia) asserts that the effect of heat treatment on the superconducting properties of Y1- xPrxBa2-ySryCu3O7 can be accounted for within the framework of a percolation model. In this picture, high-temperature heat treatment in an inert-gas atmosphere increases the difference in the Madelung potential between the Y/Pr and Ba/Sr sites by reducing the oxygen content in the Cu-O basal plane, thereby facilitating the ordering of the A-site cations (Y/Pr and Ba/Sr). The resultant smaller content of trivalent ions on the Ba/Sr site allows long Cu-O chains to develop during the subsequent low-temperature annealing in O2, thus increasing the number of holes transferred to the CuO2 plane and hence increasing the superconducting fraction. The coupling between strongly superconducting regions through weak links improves, and, as a result, Tc increases.

Noting that alumina crucibles are often used to prepare RBCO crystals, S. Uma (MPI-Stuttgart) et al. have investigated the role of Al substitution in single crystals of PrBa2Cu3O7-d (PBCO) using low- temperature magnetic susceptibility and heat capacity measurements. Heat-capacity measurements on single crystals of Al-free PBCO showed a sharp peak at 16.6 K originating from antiferromagnetic ordering of the Pr ion moments, while broader transitions were found in PrBa2Cu3-yAlyO7- d at ~~10 K for y = 0.25 and ~~5.3 K for y = 0.4.

Bi Cuprates

As reported by N. K. Man (Hanoi) et al., x-ray photoelectron spectroscopy of the Co 2p core-level spectra of Bi2Sr2CaCu2-xCoxO8+d (x = 0, 0.02, 0.1, and 0.2) reveals that Co is in a mixed valent state. In addition, there is a shift in the Sr binding energy with increasing Co concentration. A related change in Tc can be understood in terms of the change of hole concentration in the CuO2 planes.

Cylindrical polycrystalline textured Bi2Sr2CaCu2O8+d (Bi-2212) samples of diameter 1 mm and length up to10 cm have been grown by L. A. Angurel (Zaragoza) et al. using a laser-float-zone (LFZ) melting technique. Thin rods grown at rates of 15-30 mm/h had self-field Jc(77K) up to 5.5 x 10^3 A/cm^2.

As noted by Z. Han et al. (NST), commercial Bi-2223/Ag composite tapes are available now for practical applications, but a better understanding of the tapes' mechanical properties is needed so that handling will not degrade the superconducting properties. The authors define the critical strain for both tensile and bending conditions, and they suggest a criterion of 0.2% strain for characterizing the tape strength. The authors also discuss how using Ag alloys affects the tape strength.

Other Cuprates

Using transmission electron microscopy (TEM), selected-area electron diffraction (SAED), and high-resolution electron microscopy (HREM) to investigate intergrowths and atomic structures, X. F. Zhang (Los Alamos) et al. have found two intermediate structures in the Tl-Ba-Ca-Cu-O system. One of these is a defective Tl2Ba2CaCu2O8+d (Tl-2212) structure in which a large amount of Tl vacancies distribute unevenly in the (Tl- O)2 bilayers. The other is formed by ordered intergrowths along the c axis between Tl-O monolayered structures and (Tl-O)2 bilayered structures.

The question of why Eu2-xCexCuO4 is superconducting, while Eu2-zThzCuO4 is not, is discussed in a preprint by H. A. Blackstead (Notre Dame) et al. The authors propose tests that can discriminate between their charge-reservoir-oxygen model (which requires p-type doping for superconductivity) and conventional cuprate-plane models (which permit n-type doping by Th).

Experiments probing flux-pinning behavior and interlayer coupling of Hg0.7Cr0.3Sr2CuO4+d are reported by J.-H. Choi (Pohang) et al. In disagreement with previous reports, the authors found reduced flux pinning in this material. The irreversibility line and the magnetic hysteresis in this material were found to be below those of HgBa2CuO4+d [Hg(Ba)-1201]. The authors also found interlayer coupling to be weak in Hg0.7Cr0.3Sr2CuO4+d.

The effects of Cu-site substitution by Co, Ni, and Ga upon superconductivity in the tetragonal system LaBaCaCu3-xMxO7 (M = Co, Ni, and Ga) with x = 0.0, 0.06, 0.08, 0.24, and 0.30 have been investigated by V.P.S. Awana (Wollongong) et al. The superconducting transition temperature Tc decreases with x for all three choices of M.

Thin Films

The growth and characterization of superconducting Tl0.78Bi0.22Sr1.6Ba0.4Ca2Cu3O9 [(Tl,Bi)-1223] films on CeO2-buffered single-crystal yttrium-stabilized zirconia (YSZ) are reported in a preprint by Z. F. Ren (SUNY-Buffalo) et al. Four-probe transport measurements showed superconducting transition temperatures of 105-109 K, depending on the annealing conditions. At 77 K and zero external magnetic field, the transport critical current density Jc was found to be in the range of (0.6-1.0) x 10^6 A/cm^2 for samples of thickness 1.5- 1.8 micrometers.

Current-voltage (I-V) characteristics and their derivatives in YBa2Cu3O7-d/normal-metal planar and point-contact junctions have been measured by A. Plecenik (Bratislava) et al. in the voltage range up to +-2 V. The authors observed the creation of a background in the differential conductance (dI/dV), which could be changed between quadratic and linear by application of a high bias voltage of positive or negative sign. The authors explain this effect in terms of oxygen removal in the surface layer of the superconductor. They also suggest that the linear conductance background is not an intrinsic property of bulk high-temperature superconductors.

Applications

As reported by Q. X. Jia et al. (Los Alamos), directly coupled dc SQUID magnetometers on LaAlO3 substrates have been fabricated using ramp-edge superconductor/normal-metal/superconductor junctions, where Ag-doped YBa2Cu3O7-d was used for the electrode and PrBa2Cu3O7-d for the normal- metal barrier. The SQUIDs routinely displayed I_cR_n products over 120 microvolts and transfer functions of over 100 microvolt/phi_0. The authors also report the results of field-noise experiments.

The effect of film thickness on the interconnection properties between YBa2Cu3O7-d and Si for superconductor/semiconductor integration has been studied by Y. S. Jeong (Yonsei) et al. The authors report that, because of the very different thermal expansion coefficients of YBCO and Si, there is a tendency for crack formation, which interrupts the current flow and increases the normal-state resistance.

The fabrication and performance of high-temperature superconducting double-pancake coils made from (Bi,Pb)2Sr2Ca2Cu3O10+d [(Bi,Pb)-2223] multifilamentary Ag-clad tapes using a wind-and-react procedure are reported by N. V. Vo (Los Alamos). An overall I_c ~~ 7.5 A with a variation along the length of less than 12% was achieved.

As reported by R. Zeng et al. (Wollongong), with improvements in materials and processing techniques, large-grained YBa2Cu3O7-d samples with overall dimensions of 4 x 12 x 12 mm^3 and mass 18 g have been produced, each sample being capable of levitating a 1 kg weight. The authors report using the YBCO samples to construct a model high- temperature superconducting magnetic-suspension prototype train. The rails of the race track (2.8 m in circumference) consisted of two rows of rectangular NdFeB magnets of the same polarity, and the train suspension was provided by six single-grain YBCO samples, which were field cooled at 77 K using a fixed gap of 10 mm between the rails and the train. The train could thus be suspended above the magnetic alloy, and it was able to run with very low friction over the magnetic rail.

Other Activities

Observations of random telegraph voltage noise signals, characterized by a strongly nonlinear and nonmonotonic dependence of the telegraph amplitude on current flow, are reported by G. Jung (Ben Gurion) and B. Savo (Salerno) in epitaxial high-Tc thin-film strips biased with dc current flow and subjected to an external magnetic field. The authors conclude that in such films, in close analogy to granular systems, random jumps of trapped flux lines are sensed by internal Josephson junctions or interferometer structures and converted to the observed voltage fluctuations.

A preprint by A. Garg (Northwestern) discusses the implications of recent experiments on antiferromagnetic order in UPt3 for the superconducting state. The author concludes that the data make it overwhelmingly likely that superconducting UPt3 is described by two order parameters belonging to independent representations, although the precise representations involved are still debatable.

Overviews

The different families of the superconducting cuprates have been analyzed by J. Hauck and K. Mika (IFF-Juelich) using an Ising type analysis. The authors classified about 40 different crystal structures of superconducting and structurally related compounds in a crystallographic notation according to the sequence of metal atoms, and they analyzed the positions of oxygen atoms in octahedral interstices of the undistorted body-centered metal lattices. The authors suggest that their compilation might be useful in the search for new layered superconducting oxides. They also suggest that a detailed study of the physical properties of related compounds containing no CuO2 layers might be useful in understanding high-Tc superconductivity (118 refs.).

An overview of studies of quantization and confinement effects in nanostructured superconductors is presented in a paper by V. V. Moshchalkov (Leuven) et al. The authors report investigations of three different types of samples: individual structures (lines, loops, and dots), one-dimensional (1D) clusters of loops and 2D clusters of antidots, and large lattices of antidots. The critical temperature Tc(H) versus magnetic field H of each type of sample has structure related to the well-known Little-Parks oscillations of Tc(H) in mesoscopic loops (38 refs.).

Ph.D. Thesis

Experimental magnetization studies in the vortex state of high-purity YBa2Cu3O7-d single crystals are reported in the Ph.D. thesis of K. Deligiannis (Southampton). Over a broad field and temperature regime, twin planes are found to limit the critical current by facilitating vortex channeling. By comparing magnetic and transport data, the author points out that the magnetization-peak lines in the phase diagrams for YBa2Cu3O7-d and Bi2Sr2CaCu2O8+d are strikingly similar. The author also used the presence of lock-in oscillations in the magnetic hysteresis of YBa2Cu3O7-d single crystals to study pinning by the layered structure in the quasi-2D region (271 refs.).

Contributed by John R. Clem

Contents: Preprints begin on page 6; Coming Events begin on page 11; Resources are on page 13; and FYI is on page 13.

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.

PREPRINTS To obtain a particular preprint, contact the first author at the address given at the end of the citation. Help us expand this list by sending us your complete preprint. Please specify where and when your paper was submitted. An * next to an entry indicates it is a correction or revision of a previous entry. PACS codes and/or key words are given at the end of the citation.

A. M. Abakumov, M. G. Rozova, R. V. Shpanchenko, M. L. Kovba, S. N. Putilin, E. V. Antipov, O. I. Lebedev, G. Van Tendeloo, E. M. Kopnin, and J. Karpinski, "Effect of Fluorination on the Structure and Superconducting Properties of Y2Ba4Cu7O14+d Phases." To be published in Physica C (in press). Contact G. Van Tendeloo, EMAT, University of Antwerp (RUCA), Groenenborgerlaan 171, B-2020 Antwerp, BELGIUM. Key words: Y2Ba4Cu7O14+d, fluorination, electron microscopy.

Y. Abulafia, M. McElfresh, A. Shaulov, Y. Yeshurun, Y. Paltiel, D. Majer, H. Shtrikman, and E. Zeldov, "Measurement of the Magnetic Induction Vector in Superconductors Using a Double-Layer Hall Sensor Array." To be published in Appl. Phys. Lett. Department of Physics, Institute for Superconductivity, Bar-Ilan University, Ramat-Gan 52900, ISRAEL; Y. Yeshurun's telephone +972 3 531-8433 or -8434; telefax +972 3 535-3298.

T. Akachi, R. Escamilla, V. Marquina, M. Jimenez, M. L. Marquina, R. Gomez, R. Ridaura, and S. Aburto, "Site Occupancy and Tc Degradation in Iron Substituted YBa2(Cu1-xFex)4O8+d." To be published in Physica C (in press). Instituto de Investigaciones en Materiales, Universidad Nacional Autonoma de Mexico, 04510 Mexico D.F., MEXICO. Key words: high-Tc superconductors, Y124 system, iron substitution, Tc degradation, Mossbauer spectroscopy, Rietveld refinement, site occupancy. 74.25.-q; 74.10.+v; 74.62.Dh; 76.80.+y.

L. A. Angurel, J. C. Diez, E. Martinez, J. I. Pena, G. F. de la Fuente, and R. Navarro, "Growth Rate Effects on Thin Bi2Sr2CaCu2O8+d Textured Rods." To be published in Physica C. Instituto de Ciencia de Materiales de Aragon (I.C.M.A.), Departamento de Ciencia y Tecnologia de Materiales y Fluidos, Centro Politecnico Superior, Universidad de Zaragoza, Maria de Luna 3, E-50015 Zaragoza, SPAIN; telephone +34 976 761958; telefax +34 976 761957; e-mail angurel@posta.unizar.es. Key words: BSCCO, superconductivity, laser processing. 74.60.Jg.

D. K. Aswal, S. K. Gupta, P. K. Mishra, and V. C. Sahni, "Oxygen Diffusion in Silver-Free and Silver-Doped YBa2Cu3O7-d Single Crystals." Submitted to Supercond. Sci. & Technol. Contact S. K. Gupta, Technical Physics and Prototype Engineering Division, Bhabha Atomic Research Center, Mumbai 400 085, INDIA; telefax +91 22 556-0750 or -0534.

V.P.S. Awana, J. Horvat, H. K. Liu, S. X. Dou, Rajvir Singh, A. V. Narlikar, and M. P. Das, "Effect of Cu-Site Co, Ni, and Ga Substitution on the Superconductivity of Tetragonal LaBaCaCu3O7 System." To be published in Physica C (in press). Center for Superconducting and Electronic Materials, University of Wollongong, Wollongong NSW 2522, AUSTRALIA; telefax +61 2 4221-3112 or -5731; e-mail awana@uow.edu.au. 74.20.Mn; 74.25.-q; 74.62.Dh; 74.72.-h.

Victor Barzykin and Alexandre M. Zagoskin, "Nonlocality and Anomalous Critical Current Dependence on the Magnetic Flux in Mesoscopic SNS Junctions." Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, BC, CANADA V6T 1Z1; Alexandre M. Zagoskin's e-mail zagoskin@physics.ubc.ca; preprint also available at cond-mat@xxx.lanl.gov (#9805104).

F. Bass, B. Ya. Shapiro, and I. Shapiro, and M. Shvartser, "Flux- Antiflux Interface in Type-II Superconductors." To be published in Phys. Rev. B. Contact B. Ya. Shapiro, Institute of Superconductivity, Department of Physics, Bar-Ilan University, Ramat Gan 52900, ISRAEL. 74.60.Ge.

Jorge Berger and Jacob Rubinstein, "Flux-Induced Vortex in Mesoscopic Superconducting Loops." Department of Physics, Technion, 32000 Haifa, ISRAEL; e-mail phr76jb@aluf.technion.ac.il; preprint also available at cond-mat@xxx.lanl.gov (#9711043).

Howard A. Blackstead, John D. Dow, and Martin Lehmann, "Th-Doped Nd2- zCezCuO4 Homologues." Preprint #th242sub.rno. Department of Physics, University of Notre Dame, Notre Dame, IN 46556; telephone (219) 631- 7078; telefax (219) 631-5952; e-mail blackstd@rems1.phys.nd.edu. Key words: superconductivity, rare earths. 74.20.Fg.

A. I. Buzdin and A. A. Varlamov, "Regularization of the Density of States Fluctuation Contribution in Magnetic Field." Submitted to Phys. Rev. B. Centre de Physique Theorique et de Modelisation, Universite Bordeaux I, CNRS-URA 1537, F-33174 Gradignian, Cedex, FRANCE; A. A. Varlamov's e-mail at Universita de Firenze, Italy is varlamov@fi.infn.it; preprint also available at cond-mat@xxx.lanl.gov (#9804331). 74.40.+k.

Guanghan Cao, Yabin Yu, and Zhengkuan Jiao, "A Quantitative Understanding for the Tc Suppression in Y1-xPrxBa2Cu3O7." To be published in Physica C (in press). Department of Physics, Zhejiang University, Hangzhou 310027, PEOPLE'S REPUBLIC OF CHINA; telefax +86 571 7951358; e-mail phycgh@emb.zju.edu.cn. Key words: Y1-xPrxBa2Cu3O7, Tc suppression, hole transfer. 74.72.Bk; 74.62.Dh; 74.25.Jb.

P. Chaddah, S. B. Roy, and M. Chandran, "On Inferring Equilibrium Magnetization from Hysteretic M-H Curves of Type-II Superconductors." Low Temperature Physics Group, Centre for Advanced Technology, Indore 452013, INDIA. 74.60.Ge; 74.60.Jg.

Qijin Chen, Ioan Kosztin, Boldizsar Janko, and K. Levin, "Superconducting Transitions from the Pseudo-Gap State: d-Wave Symmetry, Lattice, and Low Dimensional Effects." James Franck Institute, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637; e-mail qchen@rainbow.uchicago.edu; preprint also available at cond-mat@xxx.lanl.gov (#9805032). 74.20.Mn; 74.25.-q; 74.25.Fy; 74.25.Nf; 74.72.-h.

Jae-Hyuk Choi, Mun-Seog Kim, Sung-Ik Lee, Su-Young Lee, In-Sang Yang, J. V. Yakhmi, J. B. Mandal, B. Bandyopadhyay, and B. Ghosh, "Flux-Pinning Behavior and the Interlayer Coupling of the Hg0.7Cr0.3Sr2CuO4+d Superconductor." To be published in Phys. Rev. B. Pohang Superconductivity Center and Department of Physics, Pohang University of Science and Technology, Pohang 790-784, KOREA; telefax +82 562 279 5299; e-mail jhchoi@postech.ac.kr. 74.62.Dh; 74.72.Gr; 74.60.Ge; 74.40.+k.

Konstantinos Deligiannis, "Investigations of the Vortex Phase Diagram and Pinning in YBa2Cu3O7-d Single Crystals." Submitted as a Ph.D. thesis (University of Southampton). Department of Physics, University of Southampton, Southampton SO17 1BJ, UNITED KINGDOM; telephone +44 1703 592058; telefax +44 1703 593910; e-mail kd@phys.soton.ac.uk.

Matthias Eschrig, "Electromagnetic Response of a Pancake Vortex in Layered Superconductors." Department of Physics and Astronomy, Northwestern University, Evanston, IL 60208; e-mail eschrig@snowmass.phys.nwu.edu; preprint also available at cond- mat@xxx.lanl.gov (#9804330).

Denis Feinberg, "Softening and Melting of a Vortex Lattice in Presence of Point Disorder." Laboratoire d'Etudes des Proprietes Electroniques des Solides, Centre National de la Recherche Scientifique, B.P. 166, F- 38042 Grenoble Cedex 9, FRANCE; e-mail denis.feinberg@roma1.infn.it; preprint also available at cond-mat@xxx.lanl.gov (#9805080). 74.60.Ge; 64.70.Dv; 62.20.Fe.

M. E. Gaevski, A. V. Bobyl, D. V. Shantsev, Y. M. Galperin, T. H. Johansen, M. Baziljevich, H. Bratsberg, and S. F. Karmanenko, "Magneto- Optical Study of Magnetic Flux Penetration into a Current-Carrying High- Temperature Superconductor Strip." Ioffe Physico-Technical Institute, Polytechnicheskaya 26, St. Petersburg 194021, RUSSIA; Y. M. Galperin's e-mail at University of Oslo, Norway is iouri.galperine@fys.uio.no; preprint also available at cond-mat@xxx.lanl.gov (#9805091). 74.76.Bz; 74.60.Ge; 74.60.Jg; 78.20.Ls.

Anupam Garg, "Antiferromagnetism and Superconductivity in UPt3." To be published in J. Phys.: Condens. Matter. Department of Physics and Astronomy, Northwestern University, Evanston, IL 60208; e-mail agarg@nwu.edu; preprint also available at cond-mat@xxx.lanl.gov (#9803311).

Z. Han, P. Skov-Hansen, and P. Vase, "Mechanical Properties of Bi- 2223/Ag Composite Tapes for Large Scale Applications." To be published in the Proc. of the 15th Int. Conf. on Magnet Technology (MT-15), Beijing, People's Republic of China, Oct. 20-24, 1997. Nordic Superconductor Technologies A/S, Prioparken 878, DK-2605 Brondby, DENMARK; telephone +45 4348 3529; telefax +45 4348 2501; e-mail z.han@nst.com. Key words: Bi-2223 tape, mechanical properties, strain and strength.

J. Hauck and K. Mika, "Structure Families of Superconducting Oxides and Interstitial Alloys." Submitted to Supercond. Sci. Technol. Institut fuer Festkoerperforschung, Forschungszentrum Juelich, D-52425 Juelich, GERMANY; telefax +49 2461 613916; e-mail j.hauck@fz-juelich.de.

Takayanagi Hideaki, Akazaki Tatsushi, and Toyoda Etsuko, "Critical Current-Gate Voltage Characteristics in Short- and Long-Gated Josephson Junctions." To be published in Appl. Supercond. (in press). NTT Basic Research Laboratories, 3-1 Morinosato-Wakamiya, Atsugi-Shi, Kanagawa 243-0198, JAPAN.

Y. S. Jeong, J. H. Park, D. S. Eun, S. Y. Lee, C. H. Kim, T. S. Hahn, J. Y. Kim, and I.-S. Yang, "Film Thickness Effect on the Properties of Interconnection Between YBCO and Si for Superconductor and Semiconductor Integration." To be published in Appl. Supercond. (in press). Department of Electrical Engineering, Yonsei University, Seoul 120-749, KOREA.

Q. X. Jia, F. Yan, C. Mombourquette, and D. Reagor, "Directly-Coupled dc Superconducting Quantum Interference Device Magnetometers Based on Ramp- Edge Ag:YBa2Cu3O7-x/PrBa2Cu3O7-x/Ag:YBa2Cu3O7-x Junctions." Preprint #LA-UR-98-1652; to be published in Appl. Phys. Lett. Superconductivity Technology Center, Mail Stop K763, Los Alamos National Laboratory, Los Alamos, NM 87545; telephone (505) 667-2716; telefax (505) 665-3164; e- mail qxjia@lanl.gov.

G. Jung and B. Savo, "Josephson Mechanism in Random Telegraph Voltage Noise in High-Tc Superconductors." To be published in Appl. Supercond. Department of Physics, Ben Gurion University of the Negev, P.O. Box 653, 84105 Beer-Sheva, ISRAEL; telephone+972 7 472124; telefax +972 7 281340; e-mail jung@bgumail.bgu.ac.il. 74.40.+k; 74.76.Bz; 74.50.+r; 74.60.Ge.

Randall D. Kamien, "Force Free Configurations of Vortices in High Temperature Superconductors Near H_[c2]." Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104; e-mail kamien@dept.physics.upenn.edu; preprint also available at cond- mat@xxx.lanl.gov (#9804287).

H. J. Kaufmann, E. G. Maksimov, and E.K.H. Salje, "Electron-Phonon Interaction and Optical Spectra of Metals." To be published in J. Supercond. Interdisciplinary Research Centre in Superconductivity, University of Cambridge, Madingley Road, Cambridge CB3 0HE, UNITED KINGDOM; telephone +44 1223 33 34 09; telefax +44 1223 33 34 50; e-mail hjk22@cus.cam.ac.uk; preprint also available at cond-mat@xxx.lanl.gov (#9805108). Key words: optical properties, electron-phonon interaction, high-Tc superconductors.

P. E. Kazin, M. A. Uskova, Yu. D. Tretyakov, M. Jansen, S. Scheurell, and E. Kemnitz, "Formation of Bi(Pb)-2223 with Chemically Compatible V- Rich Phase." To be published in Physica C (in press). Department of Chemistry, Moscow State University, 119899 Moscow, RUSSIA. Key words: Bi(Pb)-2223, vanadates, phase formation, magnetization.

B. Khaykovich, M. Konczykowski, K. Teitelbaum, E. Zeldov, H. Shtrikman, and M. Rappaport, "Effect of Columnar Defects on Vortex-Solid Melting Transition in Bi2Sr2CaCu2O8." To be published in Phys. Rev. B. Department of Condensed Matter Physics, Weizmann Institute of Science, 76100 Rehovot, ISRAEL; e-mail fuboris@wis.weizmann.ac.il. 74.60.Ec; 74.60.Ge; 74.60.Jg; 74.72.Hs.

A. K. Kienappel and M. A. Moore, "The Low-Field Critical End Point of the First Order Transition Line in YBa2Cu3O7-d." Submitted to Phys. Rev. Lett. Department of Physics, University of Manchester, Manchester, M13 9PL, UNITED KINGDOM; e-mail anne@a12.ph.man.ac.uk; preprint also available at cond-mat@xxx.lanl.gov (#9804314). 74.20.De; 74.25.Dw; 74.25.Ha.

W. K. Kim, J. X. Zhu, and C. S. Ting, "The Upper Critical Field of a Mixed d- and s-Wave Superconductor." Preprint #98:036; to be published in Phys. Rev. B. Texas Center for Superconductivity, University of Houston, Houston, TX 77204-5932; telephone (713) 743-8200; telefax (713) 743-8201; e-mail preprints@www.tcs.uh.edu. 74.20.-z; 74.20.Mn; 74.25.Bt.

M. Kiselev, F. Onufrieva, and Pierre Pfeuty, "Ordered 'Excitonic' Phase with Flat Bands and a Gap Increasing with Decreasing Doping as Consequence of Electronic Topological Transition in 2D System on a Square Lattice: Applications to High-Tc Cuprates." Laboratoire Leon Brillouin, CE-Saclay, F-91191 Gif-sur-Yvette, FRANCE; e-mail kisselev@llb.saclay.cea.fr; preprint also available at cond- mat@xxx.lanl.gov (#9804263). 74.25.-q; 74.72.-h; 74.25.Dw; 74.25.Ha.

R. A. Klemm, G. Arnold, C. T. Rieck, and K. Scharnberg, "Coherent Versus Incoherent c-Axis Josephson Tunneling Between Layered Superconductors." Submitted to Phys. Rev. Lett. 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.

Y. Kopelevich and S. Moehlecke, "Avalanchelike Magnetic Relaxation in the Peak-Effect Regime of Nb-O Solid Solution." To be published in Phys. Rev. B. Instituto de Fisica "Gleb Wataghin", Universidade Estadual de Campinas, Unicamp, 13083-970 Campinas, Sao Pauli, BRAZIL; telefax +55 19 788 5376; e-mail kopel@ifi.unicamp.br. 74.60.Ge; 74.60.Jg.

Ioan Kosztin, Qijin Chen, Boldizsar Janko, and K. Levin, "On the Relationship Between the Pseudo- and Superconducting Gaps: Effects of Residual Pairing Correlations Below Tc." James Franck Institute, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637; e- mail ioan@cromwell.physics.uiuc.edu; preprint also available at cond- mat@xxx.lanl.gov (#9805065). 74.20.-z; 74.25.-q; 74.62.-c; 74.72.-h.

M. Yu. Kuchiev, P. V. Shevchenko, and O. P. Sushkov, "The Bulk Josephson Response of the d-g-Wave Cuprate Superconductors." To be published in Physica C (in press). Contact P. V. Shevchenko, School of Physics, University of New South Wales, Sydney 2052, AUSTRALIA; telephone +61 2 9385 6132; telefax +61 2 9385 6060; e-mail pavel@newt.phys.unsw.edu.au. Key words: nonlinear absorption in two-gap superconductors. 74.50.+r; 74.25.Nf.

Kamlesh Kumari, S. Venkatesh, L. C. Gupta, and K. B. Garg, "A Core Level Spectroscopic Study on RNi2B2C (R=Y,Er) Borocarbides." Submitted to Jpn. J. Appl. Phys. Department of Physics, 2-3 Vigyan Bhawan, University of Rajasthan, Jaipur 302 004, INDIA; K. B. Garg's telephone +91 141 519767; telefax +91 141 511912; e-mail krishna@jp1.vsnl.net.in.

Takashi Kusao, Masaaki Egami, Satoshi Koyama, and Yuh Shiohara, "Surface Morphology and Crystallinity of Single Domain YBCO Crystal." To be published in Appl. Supercond. Superconductivity Research Laboratory, International Superconductivity Technology Center (ISTEC), 10-13 Shinonome 1-chome, Koto-ku, Tokyo 135, JAPAN; telephone +81 3 3536-5703 through -5705; telefax +81 3 3536-5714 or -5717.

Susanne Lomatch and Edward D. Rippert, "Transient Dynamics of Josephson- Coupled Multilayers." To be published in Appl. Supercond. (in press). Department of Electrical and Computer Engineering, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208-3118.

N. Luetke-Entrup, B. Placais, P. Mathieu, and Y. Simon, "rf-Studies of Vortex Dynamics in Isotropic Type-II Superconductors." Submitted to Physica B. Laboratoire de Physique de la Matiere Condensee de l'Ecole Normale Superieure, associe au CNRS et aux Universites Paris 6 et 7, 24 rue Lhomond, F-75231 Paris Cedex 05, FRANCE; B. Placais' e-mail bernard.placais@physique.ens.fr; preprint also available at cond- mat@xxx.lanl.gov (#9805093). Key words: vortices, superconductor, surface impedence, pinning, depinning transition.

Jiri Maly, Boldizsar Janko, and K. Levin, "Pairing Correlations and the Pseudo-Gap State: Application of the 'Pairing Approximation' Theory." James Franck Institute, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637; Boldizsar Janko's e-mail janko@rainbow.uchicago.edu; preprint also available at cond-mat@xxx.lanl.gov (#9805018). 74.20.Mn; 74.25.-q; 74.25.Fy; 74.25.Nf; 74.72.-h.

N. K. Man, Kamlesh Kumari, S. Venkatesh, T. D. Hien, N. K. Sinh, N. X. Phuc, and K. B. Garg, "X-ray Photoelectron Study of Bi2Sr2CaCu2- xCoxO~8." Submitted to Phys. Status Solidi. International Training Institute for Materials Science, Hanoi, Vietnam; K. B. Garg's telephone at University of Rajasthan in Jaipur, India +91 141 519767; telefax +91 141 511912; e-mail krishna@jp1.vsnl.net.in.

Dali Mao, K. Itoh, T. Kuroda, M. Yuyama, H. Wada, and Y. Murakami, "Magnetization Measurement for a Nearly Stoichiometric Nb3Al Wire." To be published in Physica C (in press). Public Laboratory of State Education Commission of People's Republic of China for High Temperature Materials and High Temperature Tests, Shanghai Jiao Tong University, 1954 Huashan Road, Shanghai 200030, PEOPLE'S REPUBLIC OF CHINA. Key words: magnetization, VSM, Nb3Al, scaling law.

P. N. Mikheenko and S. X. Dou, "Origin of Vortex Melting Line in Bi2223/Ag Tapes." To be published in Supercond. Sci. & Technol.: Proc. of the Int. Symp. on Processing and Critical Currents of HTS, Wagga Wagga, Australia, Feb. 2-4, 1998. Institute for Superconducting and Electronic Materials, University of Wollongong, Northfields Avenue, Wollongong, NSW 2522, AUSTRALIA; telephone +61 42 21 5726; telefax +61 42 21 5731; e-mail mikhe@uow.edu.au.

O. V. Misochko, "On the Superconducting Gap Observed by Electronic Raman Scattering in Bi2Sr2CaCu2O8+x." To be published in Fiz.Tv.Tela (Russian Phys. of Solid State). Institute of Solid State Physics, Russian Academy of Sciences, 142432 Chernogolovka, Moscow Region, RUSSIA; e-mail misochko@issp.ac.ru. Abstract in English, paper in Russian.

V. V. Moshchalkov, V. Bruyndoncx, E. Rosseel, L. Van Look, M. Baert, M. J. Van Bael, T. Puig, C. Strunk, and Y. Bruynseraede, "Confinement and Quantization Effects in Mesoscopic Superconducting Structures." Submitted to the Proc. of Euroschool on Superconductivity in Networks and Mesoscopic Systems, Certosa di Pontignano, Siena, Italy, Sept. 8-20, 1997. Laboratorium voor Vaste-Stoffysica en Magnetisme, Katholieke Universiteit Leuven, Celestijnenlaan 200 D, B-3001 Leuven, BELGIUM; V. Bruyndoncx's e-mail vital.bruyndoncx@fys.kuleuven.ac.be; preprint also available at cond-mat@xxx.lanl.gov (#9804267).

Michihito Muroi and Robert Street, "Inhomogeneous Superconductivity in Y1-xPrxBa2-ySryCu3O7." To be published in Physica C (in press). Research Centre for Advanced Mineral and Materials Processing, Department of Physics, University of Western Australia, Nedlands, WA 6907, AUSTRALIA; telefax +61 8 9380 1014; e-mail muroi@pd.uwa.edu.au. Key words: Y1-xPrxBa2-ySryCu3O7, substitution effects, hole concentration, percolation model, inhomogeneous superconductivity.

Fusayoshi J. Ohkawa, "Anisotropic Renormalization of Quasiparticles in Cuprate-Oxide Superconductors." To be published in Physica C (in press). Division of Physics, Graduate School of Science, Hokkaido University, Sapporo 060-0810, JAPAN. Key words: Hubbard model, 1/d expansion method, spin fluctuations, normal-state properties, pseudogap, cuprate oxides. 74.25.Jb; 71.10.Fd; 74.25.Gz.

P. V. Patanjali and V. Seshu Bai, "Weaklink Response to the Radio Frequency (MHz) Absorption in GdBCO Superconductor." To be published in Physica C (in press). School of Physics, University of Hyderabad, Hyderabad 500046, INDIA. Key words: weak links, magnetoabsorption, penetration depth.

A. Plecenik, M. Grajcar, P. Seidel, S. Takacs, A. Matthes, M. Zuzcak, and S. Benacka, "Influence of Bias Voltage History on Conductance Properties of YBaCuO/Normal Metal Junctions." To be published in Physica C (in press). Institute of Electrical Engineering, Slovak Academy of Sciences, Dubravska Cesta 9, 84239 Bratislava, SLOVAKIA. Key words: high temperature superconductors, tunneling spectroscopy, linear background, inelastic transport.

Rachel M. Quick and Sergei G. Sharapov, "The Coleman-Weinberg Effective Potential in the Theory of Superconductivity." Department of Physics, University of Pretoria, Pretoria 0002, SOUTH AFRICA; e-mail rcarter@scientia.up.ac.za; preprint also available at cond- mat@xxx.lanl.gov (#9804310). Key words: Coleman-Weinberg Method, quasi-2D superconducting metal. 11.15.Ex; 74.72.-h; 74.20.Fg.

A.I.M. Rae, E. M. Forgan, and R. A. Doyle, "The Interpretation of Magnetization and Entropy Jumps in the Mixed State of High-Temperature Superconductors." To be published in Physica C (in press). Department of Physics and Space Research, University of Birmingham, Edgbaston, Birmingham B15 2TT, UNITED KINGDOM; e-mail raeaim@novell1.bham.ac.uk; preprint also available at cond-mat@xxx.lanl.gov (#9708236). Key words: magnetization jumps, entropy jumps, high-temperature superconductors.

Z. F. Ren, W. Li, D. Z. Wang, J. Y. Lao, J. H. Wang, M. Paranthaman, D. T. Verebelyi, and D. K. Christen, "Growth and Characterization of Superconducting Films Tl0.78Bi0.22Sr1.6Ba0.4Ca2Cu3O9 on CeO2-Buffered Single Crystal YSZ." Submitted to Physica C. Department of Physics and Chemistry, and Center for Advanced Photonic and Electronic Materials (CAPEM), State University of New York at Buffalo, Buffalo, NY 14260- 3000; e-mail zren@acsu.buffalo.edu.

S. B. Roy, P. Chaddah, and Sujeet Chaudhary, "Unusual History Dependence of Magnetization In and Around the Peak-Effect Regime of CeRu2." Low Temperature Physics Group, Centre for Advanced Technology, Indore 452013, INDIA.

Andrei Shelankov, "Magnetic Force Exerted by the Aharonov-Bohm Line." Department of Theoretical Physics, Umea University, 901 87 Umea, SWEDEN; e-mail andrei.shelankov@tp.umu.se; preprint also available at cond- mat@xxx.lanl.gov (#9802158). 03.65.Nk; 67.40.Vs.

O. N. Shevtsova and S. V. Shijanovskii, "London Approximation with the Finite Core Size for the Mixed State of Type II Superconductor." To be published in Phys. Status Solidi. National Academy of Sciences, Institute for Nuclear Research, Prosp. Nauki 47, Kiev 252028, UKRAINE; telephone +380 44 265 23 49; telefax +380 44 265 44 63; e-mail shevtsova@kinr.kiev.ua. Key words: type-II superconductor, mixed state, first critical field, second critical field, vortex, circular cell approximation. 74.60.Ec; 74.20.De.

V. V. Srinivasu, John Jesudasan, Davinder Kaur, R. Pinto, and R. Vijayaraghavan, "Thickness Dependence of Microwave Surface Resistance and Critical Current Density in Ag-YBa2Cu3O7-x Thin Films." To be published in Appl. Supercond. Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400 005, INDIA.

Takuya Suzuki, Ken-ichi Yumoto, Mikito Mamiya, Masashi Hasegawa, and Humihiko Takei, "A Phase Diagram of the Bi2Sr2CuO6-CaCuO2 System in Relation to Bi-Based Superconductors." To be published in Physica C (in press). Faculty of Engineering, Fukui University, 3-9-1 Bunkyo, Fukui 910, JAPAN. Key words: phase diagram, phase stability, superconductor.

Kenji Takanaka, Hiroki Kishi, and Koichi Kuboya, "Angular Dependence of Upper Critical Field." To be published in Physica C (in press). Department of Applied Physics, Tohoku University, Sendai 980-8579, JAPAN; e-mail taka@nlap.apph.tohoku.ac.jp; Koichi Kuboya's e-mail kuboya@nlap.apph.tohoku.ac.jp. Key words: upper critical field H_[c2], multilayers, Ginzburg-Landau theory, defect structures. 74.20.De; 74.60.Ec; 74.80.Dm; 68.55.-a.

S. Uma, G. Rangarajan, and E. Gmelin, "Influence of Al Substitution in PrBa2Cu3O7-d Single Crystals." To be published in Physica C (in press). Max-Planck-Institut fuer Festkoerperforschung, Heisenbergstrasse 1, D- 70569 Stuttgart, GERMANY. Key words: Y1-xPrxBa2Cu3O7-d, magnetic susceptibility, specific heat. 74.72.Bk; 75.30.-m; 75.40.Cx.

N. V. Vo, "Advances in the Development of High Temperature Superconducting Bi-2223/Ag Pancake Coils for Electric Power Applications." Preprint #LA-UR-98-1835; to be published in Phil. Mag. B. Superconductivity Technology Center, Los Alamos National Laboratory, Mail Stop G755, Los Alamos, NM 87545; telephone (505) 665-6859; telefax (505) 665-3164; e-mail nvv@lanl.gov.

V. A. Voloshin, P. N. Mikheenko, and A. A. Gusev, "Structure and Superconducting Properties of Y1-xPrxBa2Cu3Ox." To be published in Supercond. Sci. & Technol.: Proc. of the Int. Symp. on Processing and Critical Currents of HTS, Wagga Wagga, Australia, Feb. 2-4, 1998. Donetsk Physico-Technical Institute, Ukrainian Academy of Sciences, 340114 Donetsk, UKRAINE; P. N. Mikheenko's telephone at University of Wollongong, Australia +61 242 21 5726; telefax +61 242 21 5731; e-mail mikhe@uow.edu.au.

A. Vostner, G. Brandstaetter, Tapan Chatterji, H. W. Weber, T. Sasagawa, K. Kishio, and H. Lauter, "Observation of the Flux Line Lattice in (La1- xSrx)2CuO4 Single Crystals." To be published in Solid State Commun. Atominstitut der OEsterreichischen Universitaeten, A-1020 Vienna, AUSTRIA; H. W. Weber's e-mail weber@ati.ac.at. Key words: high-Tc superconductors, phase transitions.

Z. Y. Weng, D. N. Sheng, and C. S. Ting, "Bosonic RVB Description of Doped Antiferromagnet." Preprint #98:037; 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. 71.27.+a; 74.20.Mn; 74.72.-h.

M. Werner, G. Brandstaetter, F. M. Sauerzopf, H. W. Weber, A. Hoekstra, R. Surdeanu, R. J. Wijngaarden, R. Griessen, Y. Abulafia, Y. Yeshurun, K. Winzer, and B. W. Veal, "Comparative Study of Gobal and Local Magnetization Measurements on Single Crystalline High-Tc Superconductors." To be published in Physica C. Contact H. W. Weber, Atominstitut der OEsterreichischen Universitaeten, A-1020 Vienna, AUSTRIA; e-mail weber@ati.ac.at. Key words: SQUID, torque magnetometer, Hall probe array.

Ya-Sha Yi, Zhi-Gang Yu, A. R. Bishop, and J. Tinka Gammel, "Signatures of Stripe Phases in Hole Doped La2NiO4." To be published in Phys. Rev. B. Theoretical Division and Center for Nonlinear Studies, Los Alamos National Laboratory, Los Alamos, NM 87545; e-mail yys@balder.lanl.gov; preprint also available at cond-mat@xxx.lanl.gov (#9805161). 75.60.Ch; 71.38.+i; 74.25.Nf.

R. Zeng, V. Murashov, T. P. Beales, H. K. Liu, and S. X. Dou, "High Temperature Superconducting Magnetic Levitation Train." To be published in Appl. Supercond. (in press). Center for Superconducting and Electronic Materials, University of Wollongong, Wollongong NSW 2522, AUSTRALIA.

X. F. Zhang, Y. S. Sung, and D. J. Miller, "Special Tl-Ba-Ca-Cu-O Structures: Two Intermediate States and Their Superconducting Behavior." To be published in Physica C (in press). Center for Materials Science, Mail Stop K765, Los Alamos National Laboratory, Los Alamos, NM 87545; telephone (505) 667-9243; telefax (505) 665-2992. Key words: Tl-Ba-Ca-Cu-O, structure, defect. 61.50.Em; 61.72.Nn; 74.72.Fq.

COMING EVENTS (An * indicates a previously listed event.)

June 24 - 26, 1998: 40th Electronic Materials Conference of the TMS, Charlottesville, Va. Sponsored by the Electronic Materials Committee of The Minerals, Metals & Materials Society (TMS), University of Virginia, Charlottesville, Va. The conference will provide a forum for topics of current interest and significance in the areas related to the preparation and characterization of electronic materials. Individuals actively engaged or interested in electronic materials research and development are encouraged to attend this meeting. For further information, contact The Minerals, Metals & Materials Society, 20 Commonwealth Drive, Warrendale, PA 15086; telephone (724) 776-9000; telefax (724) 776-3770; Web site http://www.tms.org/meetings/specialty/emc98/emc98.html.

*Aug. 9 - 14, 1998: Nordic Researcher Course on Power Applications for Superconductivity, Hotel Frederiksdal, Copenhagen, Denmark. The aim of this course is to impart knowledge to the participating candidates about power applications for superconductivity -- an emerging new technology which is expected to have a major impact on the future electric power generation, transmission and distribution systems. Candidates will learn about basic properties of superconductors, high-temperature superconductors, and manufacturing aspects as conductors for power applications. Power applications in cables, transformers, fault current limiters, energy storage, and motors will be discussed by specialists within these areas. Travel and lodging costs for the Nordic Ph.D. students will be paid for by NorFA. For more information, contact B. Hald, Department of Electric Power Engineering, Bldg. 325, Technical University of Denmark, DK-2800 Lyngby, Denmark; telephone +45 4525 3510; telefax +45 4588 6111; e-mail B.Hald@eltek.dtu.dk or ot@eltek.dtu.dk; Web site http://www.eltek.dtu.dk.

*Sept. 6 - 11, 1998: Gordon Research Conference on Superconductivity: Cuprate Superconductors and Related Materials, Queen's College, Oxford, United Kingdom. Colin Gough and Bertram Batlogg, Co-Chairs; M. Brian Maple, Vice-Chair. Sessions are: recent theoretical developments, influence of pairing symmetry on properties, normal-state pseudogap, c- axis conduction, new materials, proximity coupling with CMR and other materials. For information, contact Gordon Research Conferences, University of Rhode Island, P.O. Box 984, West Kingston, RI 02892-0984; telephone (401) 783-4011; telefax (401) 783-7644; e-mail app@grcmail.grc.uri.edu (for application form requests) or grc@grcmail.grc.uri.edu (for general information).

*Sept. 13 - 18, 1998: The 1998 Applied Superconductivity Conference (ASC), Marriott's Desert Springs Resort, Palm Desert, Calif. Conference will include papers in three major areas of applied superconductivity: electronics, materials, and large-scale applications. For 1998, the theme Superconductivity -- Coming to Market, will be developed through a series of plenary and invited talks. Selected papers will be published in IEEE Transactions on Appl. Supercond. For general information contact Centennial Conferences, 4800 Baseline Rd., A-112, Boulder, CO 80303; telephone (303) 499-2299; telefax (303) 499-2599; e-mail centennial@orci.com; Web site http://www.ascinc.org. For technical information, contact Ron Scanlan, Applied Superconductivity Conference, Lawrence Berkeley National Laboratory, 1 Cyclotron Rd., MS 46-161, Berkeley, CA 94720; telephone (510) 486-7241; telefax (510) 486-5310; e- mail rmscanlan@lbl.gov; Web site http://www.ascinc.org.

Sept. 14 - 20, 1998: Advanced Methods in Surfaces and Interfaces: Summer School, Institut d'Etudes Scientifiques de Cargese, Universite de Corte - Universite de Nice/Sophia-Antipolis - UMS 820 CNRS, 20130 Cargese, Corse, France. The objective of the school (limited to 80 participants/students) is to present and discuss the most recent advances in surface and interface science. Speakers will present pedagogical lectures on advanced experimental and theoretical studies of semiconductors, metals, superconductors, and biomaterials. Topics will include: optical methods, spectromicroscopy, synchrotron-radiation- related techniques, electron microscopy, electron holography, x-ray diffraction, scanning tunneling microscopy and spectroscopy (STM, STS), photoreaction and photostimulated desorption, helium atom beam scattering, dichroism, absorption spectroscopy, STM image simulation, and new generation synchrotron sources. Presentation of few selected contributed papers will also be arranged. Registration fee: FF 3,500 (participants), FF 2,500 (students). The fees include accommodation, lunch, and coffee breaks. Registration deadline, July 20, 1998. For information, contact Claude Zwicky, IPA-EPFL, CH-1015 Lausanne, Switzerland; telefax +41 21 693 4666; e-mail zwicky@ipasg.epfl.ch.

*Sept. 16 - 19, 1998: First International Conference on Inorganic Materials -- Synthesis, Characteri-zation, Properties and Applications of Inorganic Materials, Palais des Congres de Versailles, France. Conference will cover topics of interest in inorganic materials that demonstrate unusual properties which may lead to new applications. Will comprise six sessions and two poster sessions. Contributions on the latest scientific and technological results will be supplemented by a number of high-level invited presentations and reviews by experts in these fields. Poster and oral contributions are invited in the following areas: Electronic Materials -- includes systems that exhibit superconductivity, colossal magnetoresistance, or that might find applications in batteries, sensors, or optical devices, etc.; Structural Materials and Ceramics -- includes materials that are used for high- temperature applications, composites, ferroelectrics, and materials that exhibit low dielectric or unusual temperature-dependent properties; Simulation of Inorganic Materials -- includes applications of both force-field methods and first-principle techniques to inorganic materials as well as the interplay between computer simulation and experiment; Biomaterials -- will include studies on biominerals, biomimetic systems, inorganic-based biosensors, and bioinspired materials; Porous Materials -- will include crystalline nanoporous materials such as zeolites and related phases, surfactant-mediated materials, and noncrystalline nanoporous inorganics. Official language is English. A table-top exhibition will be run in conjunction with the conference. For information, contact Sue Stewart, First International Conference on Inorganic Materials Secretariat, 4 Manor Farm Barns, Church Lane, Charlton-on-Otmoor, Kidlington, Oxon OX5 2UA, United Kingdom; telephone +44 1865 331040; telefax +44 1865 331125; e-mail 101515.2472@ compuserve.com.

*Oct. 19 - Nov. 6, 1998: Experimental Workshop on High Temperature Supercon-ductors and Related Materials, San Carlos de Bariloche, Argentina. Organized by International Centre for Theoretical Physics (ICTP) and Centro Atomico Bariloche (CAB). This is the second workshop and intends to provide a general view of the state-of-the-art in the different areas of research. Main purpose is to present to the participants the personal view of the invited speakers on new research areas to be developed in the near future. Topics to be covered are: nature of the normal and superconducting state of copper oxides; thermodynamics and transport properties of the vortex structure in the liquid and solid state; normal and superconducting properties of artificial low-dimensional systems; new superconducting and related materials; material properties and characterization; optical properties of high-temperature superconductors; non-conventional superconductors; and trends in applications of HTSC materials. Workshop is open to research workers from all countries that are members of the United Nations, UNESCO, or IAEA. No registration fee. For information, contact the Abdus Salam International Centre for Theoretical Physics, P.O. Box 586, I-34100 Trieste, Italy; telephone +39 40 2240111; telefax +39 40 224163.

*May 30 - June 3, 1999: 10th International Symposium on Intercalation Compounds (ISIC 10), Okazaki, Japan. Tenth in the series. Will focus on basic ideas in both the physics and chemistry of intercalation materials such as graphite, fullerenes, carbon nanotubes, chalcogenides, oxides, clays, zeolites, and other related materials. Topics to be covered: new intercalation compounds and new synthetic routes; thermodynamics, kinetics, and reaction mechanisms; structure and lattice dynamics; phase transitions; electronic properties, charge transfer, and band structures; transport properties and superconductivity; magnetic properties; electrochemical properties; intercalation electrodes for advanced batteries; and other present and potential applications. Scientific program will consist of plenary lectures as well as oral and poster sessions. Proceedings to be published as a special issue of Molecular Crystals and Liquid Crystals. Abstract deadline, December 15, 1998. For further information, contact Toshiaki Enoki, ISIC 10, Department of Chemistry, Tokyo Institute of Technology, Ookayama, Meguro-ku, Tokyo 152-.8551, Japan; telefax +81 3-5734 2242; e-mail isic@chem.titech.ac.jp; Web site http://www.chem.titech.ac.jp/~isic/.

*July 12 - 16, 1999: Cryogenic Engineering Conference & International Cryogenic Materials Conference (CEC/ICMC), Hotel Inter-Continental Montreal, Montreal, Quebec, Canada. For information, contact Centennial Conferences, 4800 Baseline Road, Suite A-112, Boulder, CO 80303; telephone (303) 499-2299; telefax (303) 499-2599; e-mail centennial@orci.com; www.cec-icmc.org.

RESOURCES

Information

New Books: Tunneling Systems in Solids, by P. Esquinazi. Comprehensive discussion of the key experiments and latest theories concerning the dynamics of tunneling systems in solids, particularly at low temperatures. This book describes the details of relevant experiments and new theories, including introductory surveys and ideas on current research directions. Publ. 1998; 600 pp.; price $89; ISBN 3-540-63960- 8.

Electron Liquids, Second Edition, by A. Ashihara discusses newly discovered unusual electronic phenomena with emphasis on electron correlations. This edition has been enlarged to account for the significant developments in the areas of high-Tc superconductors and quantized Hall effect. Publ. 1998; 325 pp.; price $65; ISBN 3-540- 62789-8.

The Physics of Superconductors: Introduction to Fundamentals and Applications, edited by P. Mueller and A. V. Ustinov. Translated from the original Russian by I. V. Grigorieva. This revised and enlarged text is based on a lecture course given by V. V. Schmidt at the Moscow Institute of Steel and Alloys. It provides a modern treatment of the physics of superconductivity with special attention paid to the physical interpretation of the phenomenon. Publ. 1997; 120 pp.; price $59.95; ISBN 3-540-61243-2.

Contact Springer-Verlag New York Inc., 175 Fifth Avenue, New York, NY 10010; telephone (800) 777-4643; telefax (201) 348-4505; e-mail rders2springer-ny.com; Web site http://www.springer-ny.com.

FYI (High-Tc Update takes no responsibility for want ads listed in this section.)

The WWW homepage for the NIST Ceramics Division (http://www.ceramics.nist.gov/) now includes a Ceramics WebBook section which contains several data collections including one on high-Tc superconductors (WebHTS). WebHTS is a searchable database containing numeric data on the physical, mechanical, thermal, and superconducting properties of high-Tc materials.

High-Tc Update is the high-Tc superconductivity information exchange newsletter. Please send 1) preprints, reprints, and other research reports; 2) descriptions of on-going work; 3) meeting announcements and summaries.

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

Please address all contributions and inquiries to:
Dr. Sreeparna Mitra, A219 Physics,
Ames Laboratory/Iowa State University,
Ames, Iowa 50011-3020.
Telephone: (515) 294-3877 Telefax: (515) 294-1134.
E-mail: MITRA@AMESLAB.GOV
or MITRA@IASTATE.EDU.

Project Director/Editor: Sreeparna Mitra
Science Editor: John R. Clem
High-Tc Update, Vol. 12, #11, June 1, 1998.