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.

The High-Tc Update web page is located at the URL http://www.iitap.iastate.edu/htcu/htcu.html

PLEASE NOTE: Issues of High-Tc Update from November 15, 1993, onward are also available in coded Word versions (BINHEX and RTF). (These versions preserve the Greek letters, special characters, accents, etc.) If you are interested in the alternate formats, contact the editor for information.

PLEASE READ: The electronic-mail version of High-Tc Update is generated from a Macintosh Microsoft Word file and turned into a text file that can be transferred electronically. Formatting commands, Greek symbols, diacritical marks, etc. are lost in this transformation. In order to improve the readability of the e-mail version, the newsletter staff add explanatory marks as needed to the text file. For example, a carat (10^5) indicates a superscript (ten to the fifth). A carat followed by a bracket (cm^[-2]) indicates everything within the brackets is superscripted (centimeter to the minus 2). A bracket followed by a carat ([18]^O) indicates everything before the carat is superscripted. An underline (M_i) indicates a subscript (M subscript i). Most Greek letters are spelled out (Delta, mu, tau, pi, Omega), although delta is left as "d." In most instances, easily recognizable formulas or units are left as they appear: Tc, Jc, YBa2Cu3O7, O2. Mu-m is changed to micrometers. Diacritical marks (accents, tildes, carats, etc.) are removed, but the German umlaut (e.g., a, o, or u with two dots over it) is changed into a, o, or u followed by e. If needed for clarity, hyphens are occasionally inserted between spelled-out Greek letters or symbols (ohm-cm, sin-theta).

NOTA BENE:

Vortices

A preprint by Ch. Renner (Geneve) et al. reports the observation of vortex cores in both under- and overdoped Bi2Sr2CaCu2O8+d (Bi-2212) using scanning tunneling microscopy (STM). The authors find that the vortex cores in Bi-2212 do not show any signature of quasiparticle bound states, such as those observed in NbSe2 and YBa2Cu3O7-d. Inside the vortex cores of Bi-2212, the authors measure the same conductance curves as found in zero field above Tc, which show pseudogap structure [see also Ch. Renner et al., Phys. Rev. Lett. 80, 149 (1998)]. The authors suggest that the two pseudogap structures may reflect the same normal phase consisting of excited pre-existing pairs instead of the quasiparticles of the BCS theory.

Possible new vortex-matter phases in Bi-2212 crystals have been found by D. T. Fuchs (Weizmann Institute) et al. using a linear Hall array in ac experiments investigating vortex penetration through the surface barrier in the presence of a transport current. The authors used the strength of the effective surface barrier and its nonlinearity and asymmetry to identify a possible new ordered phase above the first-order transition curve in the H-T (field-temperature) plane. The authors also used this technique for a sensitive determination of the depinning temperature. Below the first-order transition curve, the authors found the solid phase to be subdivided into two phases by a nearly vertical line extending from the multicritical point.

The phase diagram of vortex matter in disordered type-II superconductors has been considered by A. van Otterlo et al. (UC-Davis) using numerical simulations in the London Langevin approximation. At low magnetic fields, the authors find a disentangled and dislocation-free Bragg-glass regime. Increasing the field introduces disorder-driven entanglement in a discontinuous manner, leading to a vortex-glass phase, which subsequently melts into the vortex liquid. The obtained phase boundaries are in good agreement with experimental data in YBa2Cu3O7-d.

Measurements of the reversible (M_[rev]) and irreversible magnetization of Bi-2212 single crystals with columnar defects (5.8 GeV Pb ions, B_[phi] = 0.3 T and 1 T) as a function of field and temperature are reported in two preprints by N. Chikumoto (SRL-ISTEC) et al. Anomalies in the magnetization were observed at a temperature-independent field of B ~~ B_[phi]/3. The authors attribute the anomaly to a transition in the coupling of pancake vortices.

A preprint by Z. Tesanovic (Johns Hopkins) presents a theoretical framework that allows a systematic solution to the problem of critical fluctuations in an extreme type-II superconductor subjected to a finite, weak magnetic field. The author recast the fluctuation problem in terms of a new superconductor in an effective magnetic field whose overall value is zero, consisting of the original uniform field and a set of neutralizing unit fluxes attached to N_[phi] fluctuating vortex lines. The author addresses the questions of (a) the relationship between Landau level-based and 3D XY-based descriptions, (b) whether a mean- field-based London model containing only magnetic field-induced vortices is sufficient to describe the vortex-lattice melting transition in the region of strong, critical fluctuations, (c) the nature of the normal phase and whether it can be usefully represented as a line liquid of field-induced vortices, and (d) the role of thermally generated vortex loops.

According to theory by O. V. Dolgov and N. Schopohl (Tuebingen), Abrikosov vortices moving with speed v towards the surface of a superconductor send out electromagnetic radiation. The authors find that the angle-frequency distribution of the intensity radiated into the vacuum displays a pronounced maximum at microwave frequencies around omega ~~ v/lambda, where lambda is the magnetic penetration depth. The authors also find that coherent motion of the flux-line lattice may lead to a huge increase (by a factor of c/2v) in the strength of the radiated power per vortex line.

Investigations on the dynamics of the driven vortex solid in clean detwinned YBa2Cu3O7-d single crystals have been carried out by S. N. Gordeev (Southampton) et al. at temperatures and fields just below the thermodynamic melting line. When an asymmetric periodically modulated drive current was applied, the authors observed voltage oscillations. The authors propose an interpretation of the oscillatory effects in terms of a defect superstructure that drifts across the sample with the same velocity as that of individual vortices.

Two papers by C. Kuebert and P. J. Hirschfeld (Florida) report theoretical calculations of the properties of d-wave superconductors in the vortex state. One of these describes the magnetic-field and temperature dependence of the thermodynamic properties and the low-field microwave conductivity as a function of the impurity scattering rate. The second paper reports calculations of the magnetic-field and temperature scaling dependence of the electronic thermal conductivity for different levels of impurity scattering.

A preprint by G. E. Volovik (Helsinki University of Technology and Landau Institute) shows that the vortex mass as calculated by Kopnin and by Baym and Chandler have the same origin: the mass of the normal component trapped by the vortex.

As noted by R. P. Huebener and F. Gollnik (Tuebingen), extremely high values of the coefficient eta_[eff] of the damping force eta_[eff]v_[phi] acting during vortex motion (v_[phi] = vortex velocity) have been reported for the electron-doped superconductor Nd1.85Ce0.15CuO4 in the low-temperature limit. The authors use a two- band model of the electronic structure of Nd1.85Ce0.15CuO4 to show that the high values of eta_[eff] are consistent with relatively small values of the overall Hall angle.

The dynamics of two-dimensional (2D) vortices in a YBa2Cu3O7- d/PrBa2Cu3O7-d superlattice have been investigated by X. G. Qiu (Leuven) et al. via measurements of the I-V (current-voltage) characteristics. The authors identified regions in the j-T (current density vs. temperature) plane in which quantum creep, plastic creep, collective creep, and Anderson-Kim creep occur. The results also suggest that a 2D vortex glass cannot exist at any temperature, including T = 0.

A preprint by I. F. Lyuksyutov (Texas A&M) and V. Pokrovsky (Texas A&M and Landau Institute) theoretically considers 2D vortices in a superconducting film with an array of magnetic dots on it. The authors find that if the dot magnetic moments are randomly oriented, uncoupled vortices can appear spontaneously, and the superconducting film may be resistive. If an applied magnetic field aligns the magnetic moments of the dots, the vortices can be pinned, thereby restoring superconductivity.

RBa2Cu3O7-d

Directional tunneling and point-contact spectroscopy measurements have been carried out by J.Y.T. Wei (Caltech) et al. on the {100}, {011}, and {001} faces of YBa2Cu3O7-d single crystals at 4.2 K. The conductance spectra show fully developed quasiparticle tunneling, Andreev reflection, and zero-bias-peak characteristics, depending systematically upon the junction orientation and impedance. A quantitative spectral analysis using the generalized formalism of Blonder, Tinkham, and Klapwijk indicates a predominantly d_[x^2-y^2] pairing symmetry, with less than 5% s-wave component in either the d + s or d + is scenario.

As shown in a preprint by V. Pasler (Karlsruhe) et al., the strong coupling of superconductivity to the orthorhombic distortion in YBa2Cu3O7-d makes possible an analysis of the superconducting fluctuations without the need to subtract any background. The authors' high-resolution capacitance dilatometry data demonstrate the existence of critical, rather than Gaussian, fluctuations over a wide temperature region (+-10 K) around Tc. The values of the amplitude ratio A+/A- = 0.9-1.1 and the leading scaling exponent |alpha| <= 0.018, determined via a least-squares fit of the data, are consistent with the 3D-XY universality class. The authors discuss small deviations from pure 3D- XY behavior.

The angle dependence of the magnetization of a single-domain YBa2Cu3O7-d sphere has been measured by B. A. Tent (Cincinnati) et al. The sample was produced using a seeded-melt-growth process in which a small NdBa2Cu3O7-d seed was used to induce domain growth through a peritectic reaction in YBCO. The authors measured the angular dependence of the magnetization in a series of zero-field-cooled (ZFC) hysteresis-loop measurements with warm-ups well above Tc between measurements at different angles. The authors found that the angle dependence exhibits a saw-tooth behavior between 0 degree and 360 degrees over a wide range of temperatures and fields.

The magnetic properties of a NdBa2Cu3O7-d single crystal before and after 5.8 GeV Pb-ion irradiation (B_[phi] = 1 T) have been investigated by N. Chikumoto (SRL-ISTEC) et al. At low temperatures (T < 40 K), a large enhancement of the hysteresis width was observed over the entire field range studied (< 7 T). However, at high temperatures (T > 40 K), the hysteresis enhancement was limited to the low-field range B < B_[phi]. The authors also observed a sharp, temperature-independent, double-peak structure around 0.2 T.

The anisotropy of the static homogeneous magnetic spin susceptibility of the antiferromagnetic CuO2 bilayers and the crystal-field parameters have been measured by A. Janossy (TU-Budapest) et al. in Gd-doped YBa2Cu3O6+x (small x) single crystals using Gd^[3+] ESR at 9, 75, 150, and 225 GHz. The authors find that the easy magnetization direction is along [100] and that there is magnetostriction leading to an orthorhombic lattice distortion.

Bi Cuprates

The motion of Josephson vortices in stacks of intrinsic Josephson junctions in Bi2Sr2CaCu2O8+d (Bi-2212) has been investigated by G. Hechtfischer et al. (Erlangen-Nuernberg). The stacks were realized as mesa structures on top of Bi-2212 single crystals. The current-voltage (I-V) characteristics were found to exhibit a field-dependent branch in external magnetic fields up to 5 T oriented parallel to the layers. Using microwave emission measurements, the authors found that this branch is due to collective motion of Josephson vortices. For magnetic fields above 1.7 T, a pronounced flux-flow step in the I-V characteristics, corresponding to a Josephson frequency of 1.5 THz, was found. In this regime, the authors also observed an intensive non- Josephson emission signal, which they believe is due to Cerenkov radiation emitted from Josephson vortices moving faster than the lowest mode velocity of the stack.

The temperature dependence of Raman spectra of both overdoped and underdoped single crystals of Bi-2212 has been studied by J. W. Quilty (Victoria University of Wellington) et al. The authors found a substantial depletion of spectral weight at low energies in underdoped samples at temperatures well above Tc, and observed a peak centered near 600 cm^[-1] in the normal-state spectra of the optimally and underdoped crystals, confirming a recent report of such a peak in underdoped crystals. The authors attribute the depletion of normal-state spectral weight in the underdoped materials to the opening of the pseudogap, but the origin of the 600 cm^[-1] peak remains unclear.

Superconducting (Tc = 90 K, Delta[T] = 1-2 K) single crystals of structurally modulated Bi-2212 have been characterized by C. de la Calle (Orleans) et al. using x-ray powder diffraction and x-ray-absorption near-edge spectra (XANES). The authors were able to explain all the observed reflections by assuming a model for the superstructure of Bi- 2212 involving one extra oxygen in the BiO planes, one C2 axis, permutations Bi <--> O with Bi cluster formation, and alternation in the same crystal of more or less ordered blocks formed by 5b and 4b units.

As noted by P. Zoller et al. (Tuebingen), despite the advantage of reduced anisotropy of (Bi,Pb)-1212 relative to (Bi,Pb)-2212, several disadvantages make the processing of (Bi,Pb)-1212 difficult. The authors report that because of (a) fast phase formation, (b) absence of pronounced grain growth in the a and b directions, and (c) grain- boundary weak links, no long-range grain alignment has been achieved in PIT (powder-in-tube) tapes. For bulk materials, however, the authors found that improved grain alignment can be obtained by varying the temperature-time processing schedule and the chemical composition of the precursor.

Results of a study of a 5 m coaxial ac transmission line model with 1 kA current capability at 77 K using Bi-2223/Ag tapes are reported by L. M. Fisher (Moscow) et al. The model contained 120 tapes for the forward line and 120 tapes for the return line. Tests of the model showed that the current capability agreed with that expected by summing the critical currents of the individual tapes. The ac losses, on the other hand, were found to be substantially larger than expected.

Four recent developments in powder-in-tube processing of Bi-2223/Ag tapes are reported in a preprint by S. X. Dou (Wollongong) et al. First, the authors have developed a cryogenic deformation process, which involves rolling or pressing the wires and tapes in supercold conditions, such as in liquid nitrogen. Cryogenic deformation has been found to improve the density, grain alignment, and Ag/oxide core interface, and to increase the dislocation density, thereby enhancing Jc and flux pinning. Second, by incorporating Pb into the Bi-2212 precursor powder, the sintering temperature can be raised above 840^oC, resulting in a significant reduction of total sintering time from several hundred hours to about 100 h. Third, the authors developed a process to eliminate the decomposition and recovery of Bi-2223 during cooling and heating to reduce the heat-treatment time for Bi-2223/Ag tapes to 20-30 h, with Jc and Bi-2223 volume fraction comparable with those treated for 120 h. Fourth, a two-stage annealing procedure in the final thermal cycle has been used to eliminate residual Bi-2201, which has been identified as one of the major causes of weak links in PIT tapes. By incorporating hot deformation in a two-step process, the authors found that texture and density are improved by the elimination of Bi-2201, resulting in a high Jc = 5.68 x 10^4 A/cm^2 (I_c = 35.6 A) at 77 K in multifilamentary tapes.

Other Cuprates

Using the [63]^Cu NMR spin-echo technique, Y. Itoh (Tokyo) et al. have found evidence for magnetic dimensional crossover in [63]^Cu-enriched overdoped La2-xSrxCuO4 (x = 0.23, Tc ~~ 20 K). The authors found nearly T^[1/2] dependence of the planar [63]^Cu nuclear spin-lattice relaxation rate in this material. Putting together the transport and magnetic properties, the authors conclude that the overdoped compound with x = 0.23 is a three-dimensional nearly antiferromagnetic metal. The results indicate that a magnetic crossover from two to three dimensions takes place as the Sr content increases beyond x ~ 0.20, consistent with the electrical dimensional crossover.

As reported by S. M. Loureiro et al. (NIRIM), a series of high-Tc superconductors (Cu,Cr)Sr2Can-1CunO2n+3+d (n = 1-9) has been synthesized under high pressure at 6 GPa and 1250-1350^oC as bulk materials. The authors note that the range of n from 1 to 9 seems to be the widest among all homologous series yet studied. The compounds are tetragonal with lattice parameters given by a ~~ 3.9 Angstroms and c ~~ [8.0 + 3.2(n-1)] Angstroms. The a-axis lattice parameter initially decreases with n, reaches a minimum at n = 3, and then increases. The superconducting properties correlate well with this variation and change from nonsuperconducting for n = 1, to the highest Tc of 103 K for n = 3, and finally to complete suppression of superconductivity for n = 8 and 9 because of insufficient carrier concentration.

Strongly overdoped samples of HgBa2Ca2Cu3O8+d (Hg-1223) and CuBa2Ca2Cu3O8+d (Cu-1223:P) with Tc's as low as 107 K and 67 K, respectively, have been prepared by H. Yamauchi (Tokyo Tech) et al. using high-pressure synthesis. Hole-doping levels in both phases could be tuned over a wide range by post-annealing in O2 or Ar atmospheres. The authors found that the irreversibility line, H_[irr] vs. T/Tc, was systematically raised with increasing oxygen/hole concentration, which was accompanied by decreasing c-axis lattice parameter and decreasing anisotropy.

Guided by the observation that compounds with simpler charge-reservoir blocks (CRBs), especially compounds whose CRBs contain two BaO layers rather than SrO layers, and compounds without rare-earth elements usually have higher Tc's, C. W. Chu et al. (TCSUH) have discovered two high-temperature superconducting homologous series of the Ba-Ca-Cu-O system using high-pressure synthesis: the interstitially doped Ba2Can- 1CunO2n+2 [02(n-1)n] for n = 3 and 4, and the CaBa2Can-1CunO2n+3 [Ca- 12(n-1)n] for n = 3. The I4-symmetric 02(n-1)n shows a Tc up to 126 K, the highest for superconductors without any volatile toxic elements, but degrades to a lower compound when exposed to air. The P4-symmetric Ca- 12(n-1)n displays a Tc not exceeding 107 K and remains stable in air. The authors report that more superconducting phases with Tc up to 120 K have been detected in the Ba-Ca-Cu-O system, although their structures have yet to be determined.

YBa2Cu4O8 single crystals have been grown in an Y2O3 crucible by S. Adachi (SRL-ISTEC) et al. using a self-flux method in a high-pressure gas mixture of 80% Ar - 20% O2. The crystals had a typical size of ~0.1 x 0.2 x 0.05 mm^3 and exhibited sharp transitions with Tc ~~ 80 K.

Thin Films

The dependence of the intergranular critical current density Jc on the angle theta of the magnetic field H relative to the c axis in a YBa2Cu3O7-d bicrystal film with a low-angle (4 degrees) [001]-tilt grain boundary has been measured by A. Dias et al. (Cambridge). The authors found that when the field is rotated in the plane of the grain boundary, the intergranular Jc displays a maximum as a function of theta for H close to the c axis. The same experiment performed in the interior of the grain shows no such maximum. The volume pinning force (F_v = JcB) at the maximum varies approximately as B^[1/2], a behavior that is consistent with vortex pinning by a dense planar distribution of line pins. The authors assert that these results are a clear demonstration of flux pinning by a linear array of dislocations in low-angle grain boundaries.

As reported in a preprint by J. A. Luine (TRW) and V. Z. Kresin (LBL), the temperature dependence of the YBa2Cu3O7-d grain-boundary-junction maximum critical current I_M has been measured and successfully described by a theoretical model that incorporates both the proximity effect and tunneling with a superconductor-normal-insulator-normal- superconductor (SNINS) structure. One of the predictions of the theory is that the grain-boundary-junction critical current density Jc is related to the reduced intergranular normal resistance rho_n via Jc ~ rho_n^[gamma], with -2 <= gamma <= -1, as widely observed.

A method to determine the stacking sequence near the surface of layered materials has been developed by J. Fompeyrine et al. (IBM-Zurich). The authors use a combination of a vacuum annealing process and friction force microscopy to reveal details of a SrTiO3 surface. Using the friction contrast, the authors show how the terminating layer of a single crystal influences the terrace edge structure.

High-Tc superconducting wires have been fabricated by R. S. Decca (Maryland) et al. by photodoping an oxygen-deficient GdBa2Cu3O6.5 thin film. An optical near-field probe was used to locally excite carriers in the system at room temperature. Trapping of the photogenerated electrons defined a confining potential for the conducting holes in the CuO2 planes. Spatially resolved reflectance measurements showed the photogenerated nanowires to be ~250 nm wide. Electron diffusion, before electron capture, is believed to be responsible for the observed width of the wires.

A preprint by Y. Yoshida (SRL-ISTEC and Nagoya) et al. describes the use of chemical vapor deposition (CVD) to deposit ultra-flat YBCO block-by- block using liquid sources.

Applications

A scanning SQUID microscope constructed from a YBCO thin-film bicrystal dc SQUID and its use to determine the volume magnetization of ultrathin magnetic films are described in a preprint by S. A. Gudoshnikov (Troitsk) et al. The device has a spatial resolution of about 100 micrometers and a field of view of 8 x 8 mm^2. The resolution of the magnetic moment of the film was close to 10-15 Am^2/Hz^[1/2] at 1 Hz.

The realization of YBCO Josephson junctions and SQUIDs on 10 x 10 mm^2 silicon bicrystal substrates and on two-inch single-crystalline wafers is reported by S. Linzen et al. (Jena). All buffer layers, YBCO films, passivation, and metallization layers were deposited with the laser- ablation technique.

Theory

A preprint by L. Balents et al. (UC-Santa Barbara) introduces and studies the nodal liquid, a zero-temperature quantum phase obtained by quantum-disordering a d-wave superconductor. The nodal liquid has a number of properties that lead the authors to suggest it as an explanation of the pseudogap state in underdoped high-temperature superconductors. In the absence of impurities, these properties include power-law magnetic order, a T-linear spin susceptibility, nontrivial thermal conductivity, and two- and one-particle charge gaps. The latter is evidenced in transport and electron photoemission, which exhibits pronounced fourfold anisotropy inherited from the d-wave quasiparticles. The authors note that the nodal liquid interpolates naturally between the d-wave superconductor and the insulating ferromagnet, and the authors' effective field theory is powerful enough to permit a detailed analysis of charge ordering, antiferromagnetism, and d-wave superconductivity.

The order parameter and density of states near a grain boundary between two d_[x^2-y^2] superconductors have been studied by M. Fogelstroem and S.-K. Yip (Northwestern and Abo Akademi). The authors examine broken time-reversal symmetry near the interface and show that, under suitable circumstances, time-reversal symmetry must be broken even when the order parameter is purely d_[x^2-y^2] everywhere in space.

Using the t-J model within a slave-boson mean-field approximation, K. Kuboki (Kobe) and M. Sigrist (Kyoto) have derived a Ginzburg-Landau free energy describing the occurrence of a locally time-reversal-symmetry- breaking state near a Josephson junction between unconventional superconductors. The authors suggest that the existing of such a junction state may explain some recent experiments on high-Tc superconductors.

A preprint by N. Schopohl and O. V. Dolgov (Tuebingen) shows that a strictly linear temperature dependence of the magnetic penetration depth lambda(T) at low temperatures is forbidden, because such a temperature dependence violates the third law of thermodynamics. From this point of view, it appears that a pure d_[x^2-y^2] pairing symmetry in clean high- Tc superconductors must become invalid for T --> 0. The authors suggest that a possible resolution is a low-temperature phase transition to a new unconventional pairing state without nodes on the Fermi surface.

A self-consistent, spin-rotational-invariant Green's function procedure has been developed by R. O. Kuzian (Kiev) et al. to calculate the spectral function of carrier excitations in the spin-fermion model for the CuO2 plane. The authors' findings are in qualitative agreement with photoemission data for undoped cuprates.

A preprint by R. Nemetschek (WMI-Garching) et al. presents a theory of electronic Raman spectra in the d + s model and uses it to explain new experimental data for an overdoped YBa2Cu3O7-d single crystal. The authors note that the model appears to provide a satisfactory description of the experimental results, which indicate a possible doping dependence of the mixing ratio. The authors also discuss the application of this model to other cuprates, including Bi-2212, Hg-1212, and Hg-1223.

The momentum-dependent lineshape of the out-of-phase oxygen vibration measured in recent neutron-scattering experiments has been investigated by T. P. Devereaux (George Washington) et al. Starting from a microscopic coupling of the phonon vibration to a local crystal field, the authors calculate the phonon line shift and broadening as a function of the transferred momentum in the superconducting state of YBa2Cu3O7-d. The authors show that the anisotropies of the density of states, superconducting energy gap, and electron-phonon coupling are all crucial to an explanation of the experiments.

The spatial distribution of the current density j in superconducting films subjected to an external field applied perpendicular to the film plane has been calculated by R. Prozorov (Bar-Ilan) et al. The authors find that, in the presence of bulk pinning, j is inhomogeneous on a length scale of the order of the intervortex distance. This inhomogeneity is significantly enhanced in the presence of surface pinning. The authors introduce a new critical-state model, which takes into account the current density variations throughout the film thickness, and show how these variations give rise to the experimentally observed thickness dependence of Jc and the magnetic relaxation rate.

Other Activities

The dynamic magnetic properties of a granular Bi-2212 sample that displays the paramagnetic Meissner effect (PME) have been studied by J. Magnusson et al. (Uppsala) using low-field ac susceptibility measurements. The results support the appearance of large spontaneous magnetic moments in the material at temperatures below Tc. While the physical origin of the magnetic moments is not distinguishable by these experiments, the data give indirect support for a pi-loop model to explain the PME. The authors do not find the dynamic behavior of their PME sample compatible with physical mechanisms involving flux compression, which have been employed to explain the positive field- cooled magnetization observed in Nb discs and single crystals of YBCO.

A preprint by H. Berger et al. (EPFL) reports transport measurements on single crystals of Sr2RuO4-d grown by the flux technique. The authors found that the temperature dependence of the Hall coefficient is similar to that in the cuprates, and that a T-linear resistivity persists up to T ~ 1000 K, while superconductivity occurs only below 1 K. The authors suggest that the linear temperature dependence of the resistivity is not an exclusive signature of the anomalous normal state of high-Tc cuprates but rather of layered oxides in general, especially single-layer perovskites, possibly independent of the magnitude of the superconducting transition temperature. The authors also suggest that Sr2RuO4-d may be used as a broad-range thermometer.

The electrical transport and superconducting properties of polycrystalline samples of SmxC60 have been investigated by X. H. Chen et al. (Hefei). Different transport mechanisms are needed to explain the resistivity versus temperature for samples with different values of x.

Overview

A brief overview of the use of Raman scattering for the investigation of phonons and electronic excitations in high-temperature superconductors has been prepared by M. Cardona (MPI-Stuttgart). The author also mentions that when the phonons lie close to the energy gap (200-400 cm^[-1]), significant changes in the frequency omega_p, linewidth Gamma, and Raman efficiency I_p occur as the temperature is lowered through the superconducting transition temperature Tc (19 refs.).

Ph.D. Thesis

The Ph.D. thesis of T. Koehler (Jena) reports investigations of the use of Ar+- and Kr+-ion lasers for the manipulation of high-temperature superconducting thin-film devices at low temperatures. The author focuses on three phenomena: (a) state switching, in which the laser produces local heating and temporarily switches the film from the superconducting to the normal state, (b) laser modification, in which oxygen diffusion occurs under local heating and permits the writing of semiconducting lines with lowered oxygen content, and (c) laser contacting, which is a method of providing electrical contacts through passivation layers of noble-metal oxides. The resistance of such a passivation layer can be varied by over seven orders of magnitude (182 refs.).

Contributed by John R. Clem

Contents: Preprints begin on page 6; Coming Events begin on page 13; and Donors are on page 15.

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.

S. Adachi, K. Nakanishi, K. Tanabe, K. Nozawa, H. Takagi, W.-Z. Hu, and M. Izumi, "Preparation of YBa2Cu4O8 Single Crystals in Y2O3 Crucible Using O2-HIP Apparatus." To be published in Physica C. 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. Key words: YBa2Cu4O8, single crystal, HIP, Y2O3 crucible, structural property, fish-tail. 61.10.Nz; 74.25.Ha; 74.62.Bf; 74.72.Bk.

J. Ambjorn, A. Avakyan, T. Hakobyan, and A. Sedrakyan, "Bethe Ansatz and Thermodynamic Limit of Affine Quantum Group Invariant Extensions of the t-J Model." Preprint #NBI-HE-98-04. Niels Bohr Institute, Blegdamsvej 17, Copenhagen, DENMARK; e-mail ambjorn@nbivms.nbi.dk or ambjorn@hetws14.nbi.dk; preprint also available at cond-mat@xxx.lanl.gov (#9802204).

V.P.S. Awana, S. X. Dou, I. Felner, I. Nowik, S. K. Malik, Apurva Mehta, Rajvir Singh, A. V. Narlikar, and W. B. Yelon, "Structural and Magnetic Properties of RSr2Fe3O9 (R = La, Y, Pr and Gd)." To be published in J. Appl. Phys. Institute of Superconducting and Electronic Materials, University of Wollongong, Wollongong NSW 2522, AUSTRALIA; telefax +61 2 4221 5731; e-mail awana@uow.edu.au.

V.P.S. Awana, S. X. Dou, Rajvir Singh, A. V. Narlikar, S. K. Malik, and W. B. Yelon, "Magnetic and Superconducting Properties of Pr in La1- xPrxBaCaCu3O7 System with 0.0 <= x <= 1.0." To be published in J. Appl. Phys. Institute of Superconducting and Electronic Materials, University of Wollongong, Wollongong NSW 2522, AUSTRALIA; telefax +61 2 4221 5731; e-mail awana@uow.edu.au.

V.P.S. Awana, T. J. Green, J. Horvat, S. X. Dou, S. J. Kennedy, Rajvir Singh, and A. V. Narlikar, "Strong Dependence of Superconducting Transition Temperature (Tc) on Intermixing of RE, Ba and Ca Sites in La and Nd Based RE:1113 Superconductors." Presented at the Int. Symp. on Processing and Critical Currents of HTS, Wagga Wagga, Australia, Feb. 2- 4, 1998; to be published in Supercond. Sci. & Technol. Institute of Superconducting and Electronic Materials, University of Wollongong, Wollongong NSW 2522, AUSTRALIA; telefax +61 2 4221 5731; e-mail awana@uow.edu.au.

Leon Balents, Matthew P.A. Fisher, and Chetan Nayak, "Nodal Liquid Theory of the Pseudo-Gap Phase of High-Tc Superconductors." Institute for Theoretical Physics, University of California, Santa Barbara, CA 93106-4030; e-mail balents@itp.ucsb.edu; preprint also available at cond-mat@xxx.lanl.gov (#9803086).

B. Bandyopadhyay, J. B. Mandal, and B. Ghosh, "Effect of TI Doping on the Structural and Physical Properties of HgBa2CuO4+d Superconductors." To be published in Physica C (in press). Saha Institute of Nuclear Physics, 1/AF, Bidhannager, Calcutta 700 064, INDIA; e-mail bidisa@hpl.saha.ernet.in. Key words: structure, electrical resistivity, thermoelectric power, Raman scattering, phase diagram.

Helmuth Berger, Laszlo Forro, and Davor Pavuna, "On Linear Resistivity from ~1 to 10^[3]K in Sr2RuO4-d Single Crystals Grown by Flux Technique." To be published in Europhys. Lett. Department of Physics, Ecole Polytechnique Federale de Lausanne, CH-1015 Lausanne, SWITZERLAND; Davor Pavuna's e-mail pavuna@dpmail.epfl.ch. 72.15.-v; 74.25.Fy; 74.72.Yg.

S. T. Bromley and D. J. Newman, "Effect of Orthorhombicity on the Superconducting Phase of the Cuprates: A Monte Carlo Study." To be published in Physica C (in press). Department of Physics, University of Southampton, Highfield SO17 1BJ Southampton, UNITED KINGDOM; telephone +44 1703 592104; e-mail sb@conmat.phys.soton.ac.uk. Key words: orthorhombicity, d wave, Van Hove. 74.20.-z; 74.25.-q.

Manuel Cardona, "Raman Scattering in High-Tc Superconductors." To be presented at the XVI Int. Conf. on Raman Scattering, Cape Town, South Africa, Sept. 1998. Max-Planck-Institut fuer Festkoerperforschung, Heisenbergstrasse 1, D-70569 Stuttgart, GERMANY

X. H. Chen, S. Y. Li, G. G. Qian, K. Q. Ruan, and L. Z. Cao, "Electronic Transport Properties of Polycrystalline SmxC60." To be published in Phys. Rev. B. Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, PEOPLE'S REPUBLIC OF CHINA; e- mail chenxh@phys.ustc.edu.cn. 74.70.Wz; 72.15.Gd; 72.80.Rj.

X. H. Chen, K. Q. Ruan, G. G. Qian, S. Y. Li, L. Z. Cao, J. Zou, and C. Y. Xu, "Effects of Doping on Phonon Raman Scattering in Bi-Based 2212 System." Submitted to Phys. Rev. B. Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, PEOPLE'S REPUBLIC OF CHINA; e-mail chenxh@phys.ustc.edu.cn. 74.72.Hs; 78.30.-j; 74.62.Dh.

Noriko Chikumoto, Marcin Konczykowski, Makoto Kosugi, Yuji Matsuda, Jun- ichi Shimoyama, and Kohji Kishio, "Influence of Columnar Defects on the Reversible Magnetization of Bi2212." To be published in Advances in Superconductivity X (Springer-Verlag, Tokyo, 1998). Superconductivity Research Laboratory, International Superconductivity Technology Center (ISTEC), 16-25 Shibaura 1-chome, Minato-ku, Tokyo 105, JAPAN. Key words: Bi2Sr2CaCu2O8+d, heavy-ion irradiation, columnar defect, reversible magnetization, Josephson plasma resonance, recoupling.

Noriko Chikumoto, Marcin Konczykowski, and Masato Murakami, "Magnetic Properties of Nd123 Irradiated by 5.8 GeV Pb-ions." To be published in Advances in Superconductivity X (Springer-Verlag, Tokyo, 1998). Superconductivity Research Laboratory, International Superconductivity Technology Center (ISTEC), 16-25 Shibaura 1-chome, Minato-ku, Tokyo 105, JAPAN. Key words: NdBa2Cu3O7-d, heavy-ion irradiation, magnetic relaxation, peak effect.

Noriko Chikumoto, Makoto Kosugi, Yuji Matsuda, Marcin Konczykowski, and Kohji Kishio, "Magnetic Studies on the Field Driven Transition from Decoupled to Coupled Pancake Vortex Phase in Bi2Sr2CaCu2O8+d with Columnar Defects." To be published in Phys. Rev. B. Superconductivity Research Laboratory, International Superconductivity Technology Center (ISTEC), 16-25 Shibaura 1-chome, Minato-ku, Tokyo 105, JAPAN. 74.60.Ge; 74.72.Bk.

C. W. Chu, Z. L. Du, Y. Y. Xue, Y. Cao, N. L. Wu, Y. Y. Sun, and I. A. Rusakova, "The Search for Novel High Temperature Superconductors: The Ba-Ca-Cu-O System." Preprint #98:026; submitted to the Proc. of the 1997 Taiwan Int. Conf. on Supercond. & 5th Workshop on Low Temp. Phys., Taipei, Taiwan, REPUBLIC OF CHINA, Aug. 13-16, 1997; to be published in Chinese J. Phys. Texas Center for Superconductivity, University of Houston, Houston, TX 77204-5932; telephone (713) 743-8200; telefax (713) 743-8201; e-mail preprints@www.tcs.uh.edu. Key words: new high- temperature superconductors, Ba-Ca-Cu-O, high-temperature superconductivity.

R. S. Decca, H. D. Drew, B. Maiorov, J. Guimpel, and E. Osquiguil, "Photoinduced Superconducting Nanowires in GdBa2Cu3O6.5 Films." Submitted to Appl. Phys. Lett. Laboratory for Physical Sciences, University of Maryland at College Park, 8050 Greenmead Drive, College Park, MD 20740; telephone (310) 935-6446; telefax (301) 935-6723; e-mail rdecca@physics.umd.edu; preprint also available at cond-mat@xxx.lanl.gov (#9803056).

C. de la Calle, J. A. Campa, C. H. Pons, and I. Rasines, "Modelling of X-ray Single-Crystal Diffraction Data for the Structurally Modulated Bi2Sr2CaCu2O8 Superconductor." Submitted to J Phys. Faculte des Sciences, CRMD, Universite d'Orleans, Rue de Chartres, B.P. 6759, F- 45067 Orleans Cedex 2, FRANCE; telefax +33 2 38 49 4674.

T. P. Devereaux, A. Virosztek, and A. Zawadowski, "Neutron Scattering and the B_[1g] Phonon in the Cuprates." Department of Physics, George Washington University, Washington, DC 20052; e-mail tpd@gwis2.circ.gwu.edu; preprint also available at cond-mat@xxx.lanl.gov (#9803175). 74.25.Gz; 74.72.Bk; 72.10.Di; 78.70.Nx.

A. Diaz, L. Mechin, P. Berghuis, and J. E. Evetts, "Evidence for Vortex Pinning by Dislocations in YBa2Cu3O7-d Low-Angle Grain Boundaries." To be published in Phys. Rev. Lett. Department of Materials Science and Metallurgy and IRC in Superconductivity, University of Cambridge, Pembroke Street, Cambridge CB2 3QZ, UNITED KINGDOM; telephone +44 1223 334375; telefax +44 1223 334373; e-mail ad228@cus.cam.ac.uk. 74.60.Ge; 74.60.Jg; 74.25.Ha; 74.72.Bk.

O. V. Dolgov and N. Schopohl, "Transition Radiation of Moving Abrikosov Vortices." Lehrstuhl Theoretische Festkoerperphysik, Eberhard-Karls Universitaet Tuebingen, Auf der Morgenstelle 14, D-72076 Tuebingen, GERMANY; N. Schopohl's telephone +49 7071 29 78635; telefax +49 7071 29 5604; e-mail nils.schopohl@uni-tuebingen.de; preprint also available at cond-mat@xxx.lanl.gov (#9802254).

S. X. Dou, R. Zeng, Y. C. Guo, Q. Y. Hu, J. Horvat, H. K. Liu, T. Beales, and M. Apperley, "Optimization of Processing to Improve Critical Current Density of Ag/Bi:2223 Tapes." Presented at the Int. Symp. on Processing and Critical Currents of HTS, Wagga Wagga, Australia, Feb. 2- 4, 1998; to be published in Supercond. Sci. & Technol. Institute for Superconducting and Electronic Materials, University of Wollongong, Wollongong NSW 2522, AUSTRALIA; telephone +61 2 4221 5730; telefax +61 2 4221 5731; e-mail shi_dou.uow.edu.au.

L. M. Fisher, A. V. Kalinov, S. E. Savel'ev, I. F. Voloshin, P. Haldar, and U. Balachandran, "Losses in Bi-2223/Ag Tapes and in the 1-kA ac Transmission Line Model." Submitted to Supercond. Sci. and Technol. All-Russian Electrical Engineering Institute, Moscow, RUSSIA; preprint also available from Contact Janice Coble, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439; telefax (708) 252-9595; e- mail janice_coble@qmgate.anl.gov.

M. Fogelstroem and S.-K. Yip, "Time Reversal Symmetry Breaking States Near Grain Boundaries Between d-Wave Superconductors." Submitted to Phys. Rev. B. Department of Physics and Astronomy, Northwestern University, Evanston, IL 60208; e-mail micke@snowmass.phys.nwu.edu; preprint also available at cond-mat@xxx.lanl.gov (#9803031).

J. Fompeyrine, R. Berger, H. P. Lang, J. Perret, E. Maechler, Ch. Gerber, and J.-P. Locquet, "Local Determination of the Stacking Sequence of Layered Materials." To be published in Appl. Phys. Lett. (in press). Contact J.-P. Locquet, IBM Research Division, Zurich Research Laboratory, Saeumerstrasse 4, CH-8803 Rueschlikon, SWITZERLAND; telephone +41 1 724 8111; telefax +41 1 724 0084; e-mail loc@zurich.ibm.com. 68.35.Bs; 81.05.Je; 81.10.-h; 81.40.Pq.

D. T. Fuchs, E. Zeldov, T. Tamegai, S. Ooi, M. Rappaport, and H. Shtrikman, "Possible New Vortex Matter Phases in Bi2Sr2CaCu2O8." Submitted to Phys. Rev. Lett. Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot 76100, ISRAEL; e-mail fndandan@wis.weizmann.ac.il; E. Zeldov's telephone +972 8 9343836; telefax +972 8 9342611. 74.25.Dw; 74.25.Fy; 74.60.Ge; 74.72.Hs.

H. Fujiki, B. Shinozaki, T. Aomine, S. Tanaka, T. Kawae, and K. Takeda, "Nonlinear Resisitivity in the Mixed State of Superconducting Aluminum Films." To be published in Physica C (in press). Department of Physics, Kyushu University, Hakozaki, Fukuoka 812, JAPAN. Key words: vortex phase transition, low-Tc superconductor, aluminum films.

J. Gerster, M. Thuerk, L. Reissig, and P. Seidel, "Hot End Loss at Pulse Tube Refrigerators." Submitted to Cryogenics. Institut fuer Festkoerperphysik, Friedrich-Schiller-Universitaet Jena, Lessingstrasse 8, D-07743 Jena, GERMANY; telephone +49 3641 947416; telefax +49 3641- 947412; P. Seidel's e-mail seidel@ifk.uni-jena.de; Web site http://www.physik.uni-jena.de/~tief/. Key words: pulse-tube refrigerators, hot end loss, heat exchanger.

S. N. Gordeev, A. P. Rassau, P.A.J. de Groot, R. Gagnon, and L. Taillefer, "Oscillatory Dynamics of the Driven Vortex Solid in YBa2Cu3O7-d Single Crystals." To be published in Phys. Rev. B. Department of Physics, University of Southampton, Highfield, Southampton SO17 1BJ, UNITED KINGDOM; A. P. Rassau's telephone +44 1 703 592058; telefax +44 1 703 593910; e-mail apr@phys.soton.ac.uk. 74.72.Bk.

Sergey A. Gudoshnikov, Ludmila V. Matveets, Konstantin A. Andreev, Alexander M. Tishin, Oleg V. Snigirev, Michael Mueck, Joerg Dechert, and Christoph Heiden, "Scanning SQUID Microscope Technique for Measurements of Ultrathin Film Magnetic Properties." To be published in Appl. Supercond. (in press). Contact Oleg V. Snigirev, Department of Physics, Moscow State University, 119899 GSP, Moscow, RUSSIA.

G. Hechtfischer, R. Kleiner, A. V. Ustinov, and P. Mueller, "Josephson Vortex Motion in Stacks of Intrinsic Josephson Junctions in Bi2Sr2CaCu2O8+x." To be published in Appl. Supercond. (in press). Contact R. Kleiner, Physikalisches Institut III, Universitaet Erlangen- Nuernberg, D-91058 Erlangen, GERMANY.

Chia-Ren Hu, "Predicted Midgap States in Unconventional Superconductors and Their Numerous Implications for High-Tc Superconductors." To be published in Int. J. Mod. Phys. B. Department of Physics, Texas A&M University, College Station, TX 77843-4242.

R. P. Huebener and F. Gollnik, "Damping of the Vortex Motion in the Electron Doped Superconductor Nd1.85Ce0.15CuOx." To be published in Phys. Rev. B. Physikalisches Institut, Lehrstuhl Experimentalphysik II, Universitaet Tuebingen, Morgenstelle 14, D-72076 Tuebingen, GERMANY; telephone +49 7071 29 76315; telefax +49 7071 29 6322; e-mail prof.huebener@uni-tuebingen.de. 74.60.Ge; 74.72.Jt.

Manzoor Hussain, Shinji Kuroda, and Koki Takita, "Peak Effect Observed in Zn Doped YBCO Single Crystals." To be published in Physica C (in press). Institute of Materials Science, University of Tsukuba, Tsukuba, Ibaraki 305, JAPAN; e-mail s945595@ipe.tsukuba.ac.jp. Key words: peak effect, Zn-doped YBCO single crystals, magnetization.

M. N. Iliev, A. P. Litvinchuk, H. G. Lee, C. L. Chen, L. M. Dezaneti, C. W. Chu, M. V. Abrashev, and V. N. Popov, "Raman Spectroscopy of SrRuO3." Preprint #98:024; submitted to the Proc. of the 16th Int. Conf. on Raman Spectroscopy (ICORS '98), Cape Town, South Africa, Sept. 6-11, 1998. 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.

Yutaka Itoh, Masahiro Matsumura, and Hideki Yamagata, "[63]^Cu NMR Evidence for Magnetic Dimensional Crossover in La2-xSrxCuO4." Submitted to J. Phys. Soc. Jpn. Institute for Solid State Physics, University of Tokyo, Roppongi, Minato-ku, Tokyo 106, JAPAN. Key words: NMR, high-Tc cuprate, spin fluctuation, dimensional crossover, overdope, La2- xSrxCuO4.

G. Jackeli and N. M. Plakida, "Dynamical Spin Susceptibility in the t-J Model." Submitted to Theor. and Math. Phys. Preprint #E17-97-266. Bogoliubov Laboratory of Theoretical Physics, Joint Institute for Nuclear Research, 141980 Dubna, Moscow Region, RUSSIA; telefax +7 095 975 23 81.

A. Janossy, F. Simon, T. Feher, A. Rockenbauer, L. Korecz, C. Chen, A.J.S. Chowdhury, and J. W. Hodby, "Antiferromagnetic Domains in (Gd Doped) YBa2Cu3O6+x." Submitted to Phys. Rev. B. Institute of Physics, Technical University of Budapest, P.O.B. 91, H-1521 Budapest, HUNGARY. 75.50.Ee; 75.25.+z; 75.30.Cr; 75.30.Gw; 75.60.Ch; 75.80.+q; 76.30.-v; 76.30.Kg; 74.72.Bk.

D. Y. Jeong and M. H. Sohn, "High Jc's Observed in Just-Rolled TI- 1223/Ag Tapes Prepared Using a TI0.8Pb0.2Bi0.2Sr1.6Ba0.4Ca2Cu3Oz Composition." To be published in Physica C (in press). Applied Superconductivity Laboratory, Korea Electrotechnology Research Institute, P.O. Box 20, Changwon 641-600, SOUTH KOREA. Key words: critical current density, densification, TI-1223 tape.

Raymund C. Jones, Mark N. Keene, and Pekik Nurwantoro, "Variational Calculations of Sheath-State Nucleation in Isotropic Type II Superconductors." To be published in Physica C (in press). School of Physics and Space Research, University of Birmingham, Edgbaston, Birmingham B15 2TT, UNITED KINGDOM. Key words: Ginzburg-Landau theory, critical field H_[c3], nucleation field.

Thomas Koehler, "Influence of Lasers on High Temperature Superconductors: Methods for Measuring and Altering Functional Layers in Cryoelectronic Devices." Submitted as a Ph.D. thesis (Friedrich- Schiller-Universitaet Jena). Fresnel Optics GmbH, Flurstedter Marktweg 13, D-99510 Apolda, GERMANY; telephone +49 3644 619686; telefax +49 3644 619580; e-mail tom_koehler@reflexite.com. (Thesis in German, abstract in English.)

C. Kuebert and P. J. Hirschfeld, "Quasiparticles in the Vortex State of Dirty d-Wave Superconductors." To be published in J. Phys. Chem. Solids: Proc. of the Conf. on Spectroscopies in Novel Supercond. (SNS'97), Cape Cod, Mass., Sept. 14-18, 1997. Department of Physics, University of Florida, Gainesville, FL 32611; e-mail chris@phys.ufl.edu; preprint also available at cond-mat@xxx.lanl.gov (#9802274). 74.25.Fy; 74.72.-h; 74.25.Jb.

C. Kuebert and P. J. Hirschfeld, "Transport Properties of d-Wave Superconductors in the Vortex State." Department of Physics, University of Florida, Gainesville, FL 32611; e-mail chris@phys.ufl.edu; preprint also available at cond-mat@xxx.lanl.gov (#9801105). 74.25.Fy; 74.72.-h; 74.60.Ec.

Kazuhiro Kuboki and Manfred Sigrist, "Time-Reversal Symmetry Breaking Surface States in t-J Model." Department of Physics, Kobe University, Kobe 657-8501, JAPAN; e-mail kuboki@phys03.phys.kobe-u.ac.jp; preprint also available at cond-mat@xxx.lanl.gov (#9803032). Key words: unconventional superconductivity, broken time reversal symmetry.

R. O. Kuzian, R. Hayn, A. F. Barabanov, and L. A. Maksimov, "Spin Polaron Damping in the Spin-Fermion Model for Cuprate Superconductors." Submitted to Phys. Rev. B. Institute for Material Science, Krjijanovskogo 3, 252180 Kiev, UKRAINE; e-mail kuz@mail.kar.net; preprint also available at cond-mat@xxx.lanl.gov (#9802074). 71.27.+a; 74.25.Jb; 74.72.-h.

C. J. Lambert, R. Seviour, and A. F. Volkov, "Conductance Suppression in Normal Metal-Superconductor Mesoscopic Structures." School of Physics and Chemistry, Lancaster University, Lancaster LA1 4YB, UNITED KINGDOM; R. Seviour's telephone +44 1524 65201; telefax +44 1524 844037; e-mail seviour@unix.lancs.ac.uk; preprint also available at cond- mat@xxx.lanl.gov (#9803114). 74.25.Fy; 73.23.-b; 72.10.-d; 72.10.Bg; 73.40.Gk; 74.50.+r.

K. Lebbou, M. Th. Cohen-Adad, R. Abraham, S. Trosset, R. E. Gladyshevskii, R. Fluekiger, P. Galez, G. W. Schulz, H. W. Weber, and M. Couach, "TI/Pb and Sr/Ba Cuprates of Type 1212: Compositional Effect on the Purity and on the Superconducting Properties." To be published in Physica C (in press). Laboratoire de Physicochimie Minerale II, Universite Claude Bernard Lyon 1, F-69622 Villeurbanne Cedex, FRANCE; telephone +33 4 7244 8130; telefax +33 4 7243 1233; e-mail lebbou@cismsun.univ-lyon1.fr. Key words: TI,Pb-1212, phase equilibria, crystal structure, high-temperature superconductors.

S. Linzen, Y. J. Tian, U. Huebner, F. Schmidl, J. Scherbel, and P. Seidel, "Application of Silicon Substrates for High-Tc Josephson Junctions and SQUIDs." Submitted to WOLTE 3, San Miniato, Tuscany, ITALY, June 24-26, 1998. Institut fuer Festkoerperphysik, Friedrich- Schiller-Universitaet Jena, Lessingstrasse 8, D-07743 Jena, GERMANY; telephone +49 3641 947413; telefax +49 3641 947412; e-mail linzen@ifk.uni-jena.de.

A. P. Litvinchuk, C. Thomsen, L. Boerjesson, and C. W. Chu, "Magnetic Excitations in Mixed (PrxY1-x)Ba2Cu4O8 Superconductors Studied by Raman Scattering." Preprint #98:025; submitted to the Proc. of the 16th Int. Conf. on Raman Spectroscopy (ICORS '98), Cape Town, South Africa, Sept. 6-11, 1998. 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.

C. Looney, J. S. Schilling, and Y. Shimakawa, "The Influence of Pressure-Induced Relaxation Effects on Tc in TISr2CaCu2O7-d." To be published in Physica C (in press). Department of Physics, Washington University, C.B. 1105, One Brookings Drive, St. Louis, MO 63130. Key words: polycrystalline TISr2CaCu2O7-d, pressure-induced relaxation effects, Tc.

S. M. Loureiro, Y. Matsui, and E. Takayama-Muromachi, "New Series of High-Tc Superconductors." Submitted to Physica C. Contact E. Takayama- Muromachi, National Institute for Research in Inorganic Materials (NIRIM), Namiki 1-1, Tsukuba, Ibaraki 305, JAPAN; telephone +81 298 51 3351; telefax +81 298 52 7449. Key words: high-Tc superconductors, HRTEM, electric resistivity, magnetic susceptibility.

Jerome A. Luine and Vladimir Z. Kresin, "High-Tc Superconductivity Grain Boundary Junctions." TRW Space and Technology Group, Redondo Beach, CA 90278.

Igor F. Lyuksyutov and Valery Pokrovsky, "Magnetization Controlled Superconductivity in a Film with Magnetic Dots." Department of Physics, Texas A&M University, College Station, TX 77843-4242; e-mail ilx@chaos.tamu.edu; preprint also available at cond-mat@xxx.lanl.gov (#9802276). 74.60.Ge; 74.76.-w; 74.25.Ha; 74.25.Dw.

J. Magnusson, E. Papadopoulou, P. Svedlindh, and P. Nordblad, "ac Susceptibility of a Paramagnetic Meissner Effect Sample." To be published in Physica C (in press). Contact P. Nordblad, Department of Materials Science, Uppsala University, Box 534, S-751 21 Uppsala, SWEDEN; telephone +46 18 471 3140; telefax +46 18 50 0131; e-mail per.nordblad@material.uu.se. Key words: paramagnetic Meissner effect, ac susceptibility, Bi-2212. 74.25.Ha; 74.50.+r; 74.72.Hs.

V. A. Moskalenko, "Electron-Phonon Interaction of Strong Correlated Systems: Strong Coupling Limit." Preprint #P17-97-248; submitted to Theor. and Math. Phys. Institute of Applied Physics, Moldavian Academy of Sciences, Academy Str. 5, Kishinev 277028, MOLDOVA; preprint also available from Joint Institute for Nuclear Research, 141980 Dubna, Moscow Region, RUSSIA; telefax +7 095 975 23 81. (Paper in Russian.)

R. Nemetschek, R. Hackl, M. Opel, R. Philipp, M. T. Beal-Monod, J. B. Bieri, K. Maki, A. Erb, and E. Walker, "d+s Wave Superconductivity: Analysis of the Electronic Raman Data of YBa2Cu3O7-d and Other Cuprates." Walther-Meissner-Institut, Bayerische Akademie der Wissenschaften, D-85748 Garching, GERMANY; M. T. Beal-Monod's telephone at Universite Paris-Sud +33 1 69 15 6928; telefax +33 1 69 15 6086; e- mail zazie@lps.u-psud.fr.

I. P. Nevirkovets, "Coherent Response of Two Nearly Identical Stacked Josephson Junctions to mm Wave Irradiation." To be published in Appl. Supercond. (in press). Department of Physics and Astronomy, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208-3112.

Volker Pasler, Peter Schweiss, Christoph Meingast, Bernhard Obst, Helmut Wuehl, Alexandre I. Rykov, and Setsuko Tajima, "3D-XY Critical Fluctuations of the Thermal Expansivity in Detwinned YBa2Cu3O7-d Single Crystals Near Optimal Doping." Submitted to Phys. Rev. Lett. Contact Christoph Meingast, Forschungszentrum Karlsruhe, Institut fuer Nukleare Festkoerperphysik, P.O. Box 3640, D-76021 Karlsruhe, GERMANY; telephone +49 7247 822188; telefax +49 7247 824624; e-mail meinga@infp.fzk.de. 74.72.-h; 64.60.Fr; 65.70.+y.

T. Plackowski, C. Sulkowski, D. Wlosewicz and J. Wnuk, "Effect of the RE^[3+] Ionic Size on the REBa2Cu3O7-d Ceramics Oxygenated at 250 Bar." To be published in Physica C. Institute of Low Temperature and Structure Research, Polish Academy of Sciences, P.O. Box 937, 50-950 Wroclaw 2, POLAND; telephone +48 71 3435021, ext. 278; telefax +48 71 441029; e-mail t.plackowski@int.pan.wroc.pl. Key words: electrical resistivity, grain boundaries, tunneling. 74.72.Bk; 74.62.Bf; 74.25.Fy; 74.50.+r.

A. K. Pradhan, K. Kuroda, and N. Koshizuka, "Dissipative Behavior and Magnetic Relaxation in Nd1+xBa2-xCu3Oy Single Crystals." 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; e-mail pradhan@istec.or.jp.

C. Prouteau, G. Duscher, N. D. Browning, and S. J. Pennycook, "Investigation of the Local Superconducting Properties in Ag-Sheathed BSCCO Tapes by STEM." To be published in Physica C (in press). Department of Physics, University of Illinois at Chicago, Chicago, IL 60607-7059. Key words: tapes, grain boundaries, hole concentration, Z contrast, EELS.

R. Prozorov, E. B. Sonin, E. Sheriff, A. Shaulov, and Y. Yeshurun, "Current Density Inhomogeneity Throughout the Thickness of Superconducting Films and Its Effect on Their Irreversible Magnetic Properties." To be published in Phys. Rev. B. Department of Physics, Institute of Superconductivity, Bar-Ilan University, 52900 Ramat-Gan, ISRAEL; e-mail prozorr@mail.biu.ac.il; preprint also available at cond- mat@xxx.lanl.gov (#9802270). 74.60.-w; 74.25.Ha; 74.76.-w; 74.60.Ge.

G. G. Qian, K. Q. Ruan, X. H. Chen, C. Y. Wang, Y. X. Wang, Q. Cao, L. Z. Cao, H. Zhang, and Y. Z. Ruan, "Normal-State Resistivity and Thermoelectric Power of Bi2Sr2-xLaxCaCu2Oy System." Submitted to Phys. Status Solidi. Contact X. H. Chen, Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, PEOPLE'S REPUBLIC OF CHINA; e-mail chenxh@phys.ustc.edu.cn.

X. G. Qiu, V. V. Moshchalkov, Y. Bruynseraede, G. Jakob, and H. Adrian, "Crossovers Between Elastic, Plastic and Quantum Creep in 2D YBa2Cu3O7/PrBa2Cu3O7 Superlattices." Submitted to Phys. Rev. Lett. Research Laboratory for Engineering Materials, Tokyo Institute of Technology, Nagatsuta 4259, Midori-ku, Yokohama 226, JAPAN; telephone +81 45 9245319; telefax +81 45 9245362; e-mail qiu@oxide.rlem.titech.ac.jp; preprint also available at cond- mat@xxx.lanl.gov (#9802253). 74.60.Ge; 74.76.-w; 74.25.Fy.

J. W. Quilty, H. J. Trodahl, and D. M. Pooke, "Electronic Raman Scattering from Bi2Sr2CaCu2O8+d: Doping Dependence of the Pseudogap and Anomalous 600 cm^[-1] Peak." To be published in Phys. Rev. B. School of Chemical and Physical Sciences, Victoria University of Wellington, P.O. Box 600, Wellington, NEW ZEALAND; telephone +64 4 471 5347; telefax +64 4 495 5237; e-mail james.quilty@vuw.ac.nz. 74.72.Hs; 74.25.Gz; 78.30.-j.

Ch. Renner, B. Revaz, K. Kadowaki, I. Maggio-Aprile, and O. Fischer, "Observation of the Low Temperature Pseudogap in the Vortex Cores of Bi2Sr2CaCu2O8+d." To be published in Phys. Rev. Lett. Departement de Physique de la Matiere Condensee, Universite de Geneve, 24 Quai Ernest- Ansermet, CH-1211 Geneva 4, SWITZERLAND; telephone +41 22 702 6111; telefax +41 22 702 6869; e-mail christophe.renner@physics.unige.ch. 74.50.+r; 74.60.Ec; 74.72.-h.

C. Rial, E. Moran, M. A. Alario-Franco, U. Amador, J. L. Martinez, J. Rodriguez-Carvajal, and N. H. Andersen, "Effects of Extra Oxygen on the Structure and Superconductivity of La2-xCaxCuO4+y Prepared by Chemical Oxidation." To be published in Physica C (in press). Contact U. Amador, Dpt. Quimica Inorganica y Materiales, F.C.C. Experimentales y Tecnicas, Universidad San Pablo-CEU, Urb. Monteprincipe, E-28668 Boadilla del Monte, Madrid, SPAIN; telefax +34 1 351 0475; e-mail uamador@hendrix.ceu.es. Key words: La2-xCaxCuO4+y, La2CuO4, superconductivity, neutron diffraction, oxygen stoichiometry.

P.V.P.S.S. Sastry, K. M. Amm, D. C. Knoll, S. C. Peterson, and J. Schwartz, "Synthesis and Processing of (Hg,Pb)1Ba2Ca2Cu3Oy Superconductors." To be published in Physica C (in press). Magnet Science and Technology, National High Magnetic Field Laboratory, Florida State University, 1800 East Paul Dirac Drive, Tallahassee, FL 32130; telephone (850) 644-1447; telefax (850) 644-0867; e-mail pamidi@magnet.fsu.edu. Key words: (Hg,Pb)Ba2Ca2Cu3Oy superconductor, Pb doping, CaHgO2 source, magnetization.

N. Schopohl and O. V. Dolgov, "On the T Dependence of the Magnetic Penetration Depth in Unconventional Superconductors at Low Temperatures: Can It Be Linear?" Institut fuer Theoretische Physik, Eberhardt-Karls Universitaet Tuebingen, Auf der Morgenstelle 14, D-72076 Tuebingen, GERMANY; e-mail nils.schopohl@uni-tuebingen.de; preprint also available at cond-mat@xxx.lanl.gov (#9802264). 74.25.Nf; 74.20.Fg; 74.72.Bk.

Rajvir Singh, A. V. Narlikar, V.P.S. Awana, J. Horvat, and S. X. Dou, "Synthesis, Structural Aspects and Superconductivity of La1- xRExBaCaCu3O7 with RE = Nd, Dy, Sm and Pr." To be published in Physica C. Contact V.P.S. Awana, Institute of Superconducting and Electronic Materials, University of Wollongong, Wollongong NSW 2522, AUSTRALIA; telefax +61 2 4221 5731; e-mail awana@uow.edu.au. 74.72.Bk; 74.72.Dn; 74.25.Fy; 74.62.Bf; 74.62.Dh.

Y. S. Sudershan, Amit Rastogi, S. V. Bhat, A. K. Grover, Y. Yamaguchi, K. Oka, and Y. Nishihara, "Vortex Dynamics at rf Frequencies in Bi2Sr2CaCu2Od Single Crystals." To be published in Physica C (in press). Contact S. V. Bhat, Department of Physics, Indian Institute of Science, Bangalore 560 012, INDIA; e-mail svbhat@physics.iisc.ernet.in. Key words: Bi2212, rf absorption, vortex decoupling, H-T phase diagram.

B. A. Tent, D. Qu, Donglu Shi, W. J. Bresser, Punit Boolchand, and Zhi- Xiong Cai, "Angle Dependence of Magnetization in a Single-Domain YBa2Cu3Ox Sphere." Submitted to Phys. Rev. B. Department of Materials Science and Engineering, University of Cincinnati, Cincinnati, OH 45211.

Zlatko Tesanovic, "Extreme Type-II Superconductors in a Magnetic Field: A Theory of Critical Fluctuations." Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218; e-mail zbt@pha.jhu.edu. 74.40.+k; 74.25.Bt; 74.20.De; 74.25.Dw; 74.25.Ha; 74.60.Ec.

S. I. Tyutyunnikov, V. N. Shalyapin, S. N. Shashkov, and N. Skyntee, "Optical Constants of High Temperature Superconductor YBa2Cu3O7-d in a Large Spectral Range are Presented." Preprint #14-97-299. Joint Institute for Nuclear Research, 141980 Dubna, Moscow Region, RUSSIA; telefax +7 095 975 23 81. (Paper In Russian.)

Anne van Otterlo, Richard T. Scalettar, and Gergely T. Zimanyi, "The Phase Diagram of Disordered Vortices from London Langevin Simulations." Submitted to Phys. Rev. Lett. Instituut-Lorentz for Theoretical Physics, P.O.B. 9506, 2300 RA Leiden, THE NETHERLANDS; e-mail avo@lorentz.leidenuniv.nl; preprint also available at cond- mat@xxx.lanl.gov (#9803021). 74.60.Ge; 74.25.Dw.

C. Varanasi, R. Biggers, I. Maartense, T. L. Peterson, J. Solomon, E. K. Moser, D. Dempsey, J. Busbee, D. Liptak, G. Kozlowski, R. Nekkanti, and C. E. Oberly, "YBa2Cu3O7-x-Ag Thick Films Deposited by Pulsed Laser Ablation." To be published in Physica C (in press). University of Dayton Research Institute, 300 College Park, Dayton, OH 45469-0177; telephone (937) 255-4474, ext. 3255; telefax (937) 656-4095; e-mail varanac@possum.appl.wpafb.af.mil. Key words: applications of high-Tc superconductors, thin films, ac susceptibility. 74.25.-q; 74.25.Fy; 74.72.Bk; 74.76.-w; 74.72.Bk.

G. E. Volovik, "Vortex Mass in BCS Systems: Kopnin and Baym-Chandler Contributions." Low Temperature Laboratory, Helsinki University of Technology, P.O. Box 2200, FIN-02015 HUT, FINLAND; e-mail volovik@boojum.hut.fi; preprint also available at cond-mat@xxx.lanl.gov (#9801011). 67.57.De; 74.60.Ge.

J.Y.T. Wei, N.-C. Yeh, D. F. Garrigus, and M. Strasik, "Directional Tunneling and Andreev Reflection on YBa2Cu3O7-d Single Crystals: Predominance of d-Wave Pairing Symmetry Verified with the Generalized BTK Theory." Department of Physics, California Institute of Technology, Pasadena, CA 91125. 74.50.+r; 74.72.Bk; 74.80.Fp.

Wenbin Wu, K. H. Wong, and P. W. Chan, "Epitaxial Growth of a-Axis Oriented YBa2Cu3O7-y/LaNiO3 Heterostructures on (100) SrTiO3 by Pulsed Laser Deposition." To be published in Physica C (in press). Structure Research Laboratory, University of Science and Technology of China, Academia Sinica, Hefei 230026, PEOPLE'S REPUBLIC OF CHINA; e-mail apwbwu@hkpucc.polyu.edu.hk. Key words: pulsed laser deposition, LaNiO3 films, a-axis oriented YBCO/LNO heterostructures. 74.76.Bz; 81.15.Fg.

H. Yamauchi, M. Karppinen, K. Fujinami, T. Ito, H. Suematsu, K. Matsuura, and K. Isawa, "Strongly Overdoped States and Irreversibility- Field Characteristics of the Hg-1223 and Cu-1223:P Superconducting Cuprates." Submitted to the Proc. of the Int. Symp. on Processing and Critical Currents of HTS, Wagga Wagga, Australia, Feb. 2-4, 1998. Materials & Structures Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 227, JAPAN; telephone +81 45 924 5315; telefax +81 45 924 5365; e-mail yamauchi@materia.titech.ac.jp.

Masahiro Yasukawa and Norimitsu Murayama, "A Phase Transition with an Abrupt Electrical Resistivity Change Around 800 K in BaBi0.5Pb0.5O3." To be published in Physica C (in press). National Industrial Research Institute of Nagoya, 1-1 Hirate-cho, Kita-ku, Nagoya 462, JAPAN. Key words: charge-density waves, electrical resistivity, metal-insulator transition, structural phase transition, thermoelectric power.

Yutaka Yoshida, Yoshiaki Ito, Hisashi Nagai, Yoshiaki Takai, Izumi Hirabayashi, and Shoji Tanaka, "Preparation and Surface Morphology of YBa2Cu3O7-y Films by Metalorganic Chemical Vapor Deposition Block by Block Deposition Using Liquid Sources." Preprint #N97412; to be published in Physica C. Superconductivity Research Laboratory, International Superconductivity Technology Center (ISTEC), Nagoya 456, JAPAN. Key words: YBa2Cu3O7-y, thin film, AFM, surface morphology, MOCVD, liquid source, block-by-block method.

Liyuan Zhang, Xiaoqiang Yang, and Changfeng Chen, "On the Characteristics of the Pseudogapped Metallic State of High-Tc Superconductors." Presented at the First Int. Conf. on New Theories, Discoveries, and Applications of Superconductors and Related Materials (New3SC-1), Baton Rouge, La., Feb. 19-24, 1998; to be published in Int. J. Mod. Phys. B. Department of Physics, Beijing University, Beijing 100871, PEOPLE'S REPUBLIC OF CHINA; e-mail zhangly@bimp.pku.edu.cn.

Y. G. Zhao, Z. W. Dong, M. Rajeswari, R. P. Sharma, and T. Venkatesan, "Electrical Transport Properties of Highly Doped PrBa2-xSrxCu3O7 Thin Films Prepared by Pulsed Laser Deposition." Submitted to Phys. Rev. B. Center for Superconductivity Research, Department of Physics, University of Maryland, College Park, MD 20742-4111. 74.72.Bk; 74.25.Fy; 74.76.-w.

H. Zheng, M. Jiang, B. W. Veal, H. Claus, and B. Obst, "Growth Rate Dependence of Physical Properties of YBa2Cu3Ox Single Crystals." To be published in Physica C. Contact Janice Coble, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439; telefax (708) 252-9595; e-mail janice_coble@qmgate.anl.gov.

Marco Zoli, "Two- and Three-Dimensional Polaronic Motion: Beyond the Holstein Model." To be published in Phys. Rev. B. Dipartimento di Matematica e Fisica, Sezione INFM, Universita di Camerino, Via Madonna delle Carceri, I-62032 Camerino, ITALY; e-mail zoli@camserv.unicam.it. 63.20.Kr; 63.20.Pw; 71.38.+i.

P. Zoller, A. Ehmann, J. Glaser, W. Wischert, and S. Kemmler-Sack, "Melt Texturing and Thermomechanical Processing of (Bi,Pb)-1212 Superconductors." Submitted to Physica C. Institut fuer Anorganische Chemie der Universitaet, Auf der Morgenstelle 18, D-72076 Tuebingen, GERMANY. Key words: melt texturing, Bi-1212, grain boundaries, electrical resistivity, critical current density.

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

*May 10 - 13, 1998: International Cryogenic Materials Conference (ICMC'98) -- Topical Conference on Loss and Stability in High-Tc and Low-Tc Superconductors, University of Twente, Enschede, The Netherlands. Aim is to bring together experts working on the electrodynamics of technical superconductors. In particular, ac loss and stability issues in high-Tc and low-Tc conductors are addressed. Contributions for both materials are requested for better understanding of ac loss, current distribution, and stability. Key topics are: ac losses in tapes, wires, cables, and coated conductors; effectiveness of filament decoupling layers, twisting, and mixed-alloy matrices; strand coating and sheet barriers to decouple cable stages (ITER, SMES, and other pulsed magnets); cores in Rutherford cables to decouple crossing strands (accelerator magnets); geometrical effects -- multilayers of tapes in high-Tc cables, non-uniform dB/dt, non-equal current sharing; and physical and numerical modelling of ac losses and stability -- similarities and differences between high-Tc and low-Tc conductors, multiple time constants in multistage cables, and continuum versus network models. For information, contact Arend Nijhuis, Conference Secretary, P.O. Box 217, NL 7500 AE Enschede, The Netherlands; telephone +31 53 489 3841; telefax +31 53 489 1099; e-mail icmc98@tn.utwente.nl.

*May 12 - 13, 1998: Pulsed Laser Deposition Technological Barriers -- Research Needs and Opportunities, Holiday Inn Arlington at Ballston, Va. Hosted by National Institute of Standards and Technology (NIST) and Naval Research Laboratory (NRL). Purpose is to examine technological barriers that may be limiting the wider application of PLD. Some issues include: scale-up; particulate control; development of process measurement and control protocols; and issues concerned with film quality including stoichiometry, epitaxy, and structure. Leading representatives from industry, federally funded laboratories, and academia will discuss techniques, problems, and future directions of PLD. Representatives from government research-directing agencies such as NSF, ONR, DARPA, DOE, and others will be present for discussion of research issues and support for pre-commercial efforts. Workshop format will consist of series of discussions that begin with short presentations by the discussion leaders. Discussion topics will include: technical barriers; the perceived role for NIST, DOD, national laboratories, NSF-universities, and industry; and strengths and weaknesses of PLD for its development as a practical commercial process. Workshop proceedings volume is planned. Registration deadline, April 3, 1998. Registration fee $100. For information, contact Kathy Jackson, Code 6670, Naval Research Laboratory, Washington, DC 20376; telephone (202) 404-2085; e-mail kjackson@ccf.nrl.navy.mil; Web site http://amp.nrl.navy.mil/code6670/workshop.html.

July 20 - 31, 1998: Tenth Trieste Workshop on Open Problems in Strongly Correlated Electron Systems, Miramare, Trieste, Italy. Workshop will include both experimentalists and theorists, and will foster the interaction between these two components of the field. Program will consist of shorter research seminars and longer tutorial lectures; lectures will contain a large element of review and pedagogy to facilitate the dissemination of the significant advances that have taken place in this field. Afternoons will be devoted to tutorials and informal discussions. Topics of special attention include: disorder and strong correlations, realizations of correlated electron physics in mesoscopic devices, non-Fermi-liquid physics, experimentally motivated aspects of cuprate physics, old and new puzzles in heavy fermion physics, and other new phenomena in transition metal oxides. 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; telephone +39 40 2240111; telefax +39 40 224163; e-mail smr1068@ictp.trieste.it; Web site http://www.ictp.trieste.it/.

Sept. 9 - 16, 1998: OXSEN Spin Electronics Summer School, Oxford, United Kingdom. Purpose is to provide a comprehensive theoretical and practical grounding in the essential physics, materials science, and electronic analysis techniques which underpin the science of spin electronics. Particular emphasis on the elaboration of both oxide spin electronics and hybrid spin electronics which respectively concern the implementation of device physics and technology based on metal/magnetic- oxide systems and magnetic-metal/semiconductor systems. Course will consist of both seminars and related classes given by a spectrum of international experts in the various fields. Lecture topics include the following subjects: fundamentals of electronic device operation, noise theory and circuit optimization, contact theory including the metal/semiconductor interface, general GMR theory, spin accumulation, GMR in granular materials, CMR materials, magnetization dynamics and reversal mechanisms, spin depolarization and precession, tunneling including spin-dependent tunneling, theory and practice, Coulomb blockade, spin-polarized surface analysis, spin diffusion-length measurements, deposition techniques, lithography and device fabrication, and semiconductor processing/device design and fabrication. For further information, contact John Gregg, Clarendon Laboratory, Parks Road, Oxford OX1 3PU, United Kingdom; telephone +44 01865 272 311; telefax +44 01865 272 400; e-mail gregg@ermine.ox.ac.uk; Web site www- cmphys.physics.ox.ac.uk/research/groups/mesomagnetism/school/oxsen.html.

*Sept. 25 - Oct. 2, 1998: First Crete Euroconference on Anomalous Complex Superconductors (ACS-I), Heraklion, Greece. Objective is to initiate a simultaneous comparative study of characteristic anomalies of high-Tc superconductors and analogous anomalies in other "complex'' superconductors like heavy fermions, organics, fullerides, borocarbides, ruthenates, etc. In-depth simultaneous comparative analysis of all manifestations of complex behavior in the various materials will be pursued in order to "distinguish relevant from irrelevant aspects for high-Tc superconductors and to obtain some systematic theoretical understanding of the mechanisms through which this complex behavior influences Tc." For further information, contact Georgios Varelogiannis, IESL-FORTH, P.O. Box 1527, 71110 Heraklion Crete, Greece; telephone +30 81 391565; telefax +30 81 391569; e-mail varelogi@iesl.forth.gr.

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.

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Project Director/Editor: Sreeparna Mitra Science Editor: John R. Clem High-Tc Update, Vol. 12, #7, April 1, 1998.