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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Physics Tomorrow essay-contest winner Paul Grant (EPRI) presents a humorous futuristic look at progress in high-Tc superconductivity research in the year 2028, describing the discovery of "Little's Elixir," a computationally designed polymer with Tc greater than 600 K and structural properties similar to DNA! See Physics Today 51, No. 5 (May 1998).
The possibility of superconductivity above 250 K in Tl1.8Ba2.0Ca2.6Cu3O10+d at high pressure, as indicated by sharp resistance changes versus temperature at 4.3 GPa, is reported by C. Y. Han et al., Fizika Nizkikh Temperatur 24, 305 (1998). Readers should be aware, however, that this finding has yet to be verified by other groups.
Vortices
A new electron-beam-scanning technique for the imaging of singly quantized vortices in type-II superconductors with a resolution of 1-2 micrometers has been developed by J. Martin (Tuebingen) et al. Using superconducting Nb/AlOx/Nb junctions at 1.6 K, the authors imaged Abrikosov vortices oriented perpendicular to the barrier plane but trapped in a superconducting tunnel junction. The voltage signal dV(x,y) of the current-biased junction was recorded as a function of the beam coordinates (x,y). The top Nb electrode was covered with an SiO2 film of 300 nm thickness, absorbing most of the 5 keV beam energy. The authors explain the signal generating the image using a model in which beam-induced electronic excitations in the SiO2 overlay film are trapped in the local magnetic field protruding from a vortex, resulting in a locally increased recombination rate.
The specific heat of a high-purity, twinned crystal of DyBa2Cu3O7.00 (Tc = 90.16 K) grown in a BaZrO3 crucible has been measured by B. Revaz et al. (Geneve) in magnetic fields B||c and B perp. to c up to 16 T. The authors observed first-order-like specific-heat peaks on the vortex- lattice melting line from ~6T to 16 T (B||c) with an entropy jump of 0.5+-0.1 k_B/vortex/layer. The fields B_m and peak temperatures T_m were found to obey the relation B_m(T_m) = (139 T)(1 - T_m/Tc)^[1.33]. The measured anisotropy factor of the effective masses was gamma = (m_c/m_[ab])^[1/2] = 5.3+-0.5. These results agree well with those for nonmagnetic, twinned YBa2Cu3O7.00.
Torque magnetometry is a powerful method for measuring the superconducting anisotropy gamma in the mixed state. As pointed out by M. Willemin (Zurich and IBM-Zurich) et al., in order to use the three- dimensional anisotropic London model to analyze torque data, the vortex lattice must be in a reversible state, which normally is restricted to a narrow range close to the upper critical field H_[c2](T) because of large pinning effects that set in at lower temperatures T. The authors found that applying an additional oscillating magnetic field perpendicular to the main field B leads to a fast depinning of the vortex lattice. This vortex-shaking process dramatically extends the reversible domain in the (H,T) phase diagram, and hence the range over which torque investigations can be made.
A numerical study of the statics and dynamics of a model three- dimensional vortex lattice at low magnetic fields has been carried out by S. Ryu and D. Stroud (Ohio State). At low fields, the authors find a weakly first-order phase transition at T_m, at which the vortex lattice melts into a line liquid. Phase coherence parallel to the field persists until a sharp crossover, conceivably a phase transition, at T_l > T_m, which develops an infinite vortex tangle. The authors find that while the magnetization jump coincides with the first-order transition in the dense limit, the jump in the low-density regime originates from the screening effect of thermally generated vortex loops and does not necessarily coincide with the melting transition of the vortex lattice. The authors thus suggest that some experimental puzzles in the low- density regime (less than about 1 T for YBa2Cu3O7-d or 10 mT for Bi2Sr2CaCu2O8+d) may be resolved in terms of a vortex-loop unbinding picture.
The crossing point of the magnetization versus temperature appearing below Tc in highly anisotropic superconducting cuprates has been measured by J. Mosqueira (Universidad de Santiago de Compostela) et al. in various compounds with different numbers N of closely spaced superconducting CuO2 layers per periodicity length s and different values of s. By correcting the measurements with different extrinsic inhomogeneity effects through the Meissner fraction, the authors demonstrate that in the high-magnetic-field limit the intrinsic crossing point may be explained at a quantitative level using the theory of Z. Tesanovic et al. [Phys. Rev. Lett. 69, 3563 (1992)] based on thermal fluctuations of 2D pancake vortices with an effective periodicity length s, independent of N.
The response of a vortex core in a layered superconductor to ac electromagnetic fields with frequencies omega <= 2[Delta]/h has been calculated by M. Eschrig (Northwestern) et al. The authors find that in this frequency range the response is dominated by order-parameter collective modes that are coupled to the vortex-core bound states of Caroli, de Gennes, and Matricon. The authors find that the vortex core has a more complex and richer dynamics than predicted by previous theories. The ac field drives an oscillating, nearly homogeneous supercurrent in the direction of the electric field, superimposed upon a dissipative current flow, which has a dipolar spatial structure. The order parameter response at low frequencies is an approximately rigid collective motion of the vortex structure perpendicular to the external field, but this structure becomes strongly deformed at frequencies of order omega >= 0.5[Delta]/h[bar].
The dynamic vortex mass has been calculated by N. B. Kopnin (Landau Institute and Argonne) and V. M. Vinokur (Argonne) for clean Fermi superfluids, including both s- and d-wave superconductors, as a response to vortex acceleration. Expressing the vortex mass as a tensor, the authors show that the diagonal component dominates in the extremely clean limit of long quasiparticle mean free time, while the off-diagonal mass dominates in the moderately clean regime.
Two papers by P. Ao and X.-M. Zhu (Umea) discuss the core-state contribution to the viscous drag coefficient eta for a vortex moving in a type-II superconductor. The authors find that in the dirty limit, the core contribution saturates to a value determined by the Fermi energy and the order parameter, independent of the normal-state resistivity.
An experimental study by J. E. Berger (Brown) et al. of the peak effect in weakly disordered 2H-NbSe2 favors a description in which the peak effect arises from a crossover between the Larkin pinning length and a rapidly falling elastic length in a vortex phase populated with thermally excited defects. A study of the thickness dependence of the peak effect at varying driving currents suggests that both screw and edge dislocations are involved in the vortex-lattice disordering.
RBa2Cu3O7-d
A preprint by A. Erb (Geneve) et al. reports on the use of three different and complementary measurements (magnetization, positron annihilation, and NMR) providing evidence that the formation of oxygen- vacancy clusters is the origin of the fishtail anomaly in YBa2Cu3O7-d (Y-123). While the anomaly is intrinsically absent in YBa2Cu3O7.0, it also can be suppressed in the optimally doped state (YBa2Cu3O6.92), where vacancies are present. The authors thus conclude that single vacancies or point defects cannot be responsible for the fishtail anomaly, but that clusters of oxygen vacancies are the origin of this effect.
Raman measurements by M. Kaell (Chalmers University of Technology and Riso) et al. in YBa2Cu3Ox (x = 6.72-6.82) reveal intense phonon scattering due to an electronic resonance localized near oxygen vacancies in the CuO chains. Below room temperature, the resonance can be photo-bleached in a manner similar to reported persistent photo- induced superconductivity effects, indicating photon-assisted oxygen ordering or electron vacancy capture. By comparing Raman and x-ray diffraction data, the authors established a correlation between the stability of the photo-induced state and the oxygen-ordering kinetics in the CuO chains.
Compton scattering, i.e., inelastic x-ray scattering with very high momentum and energy transfer, is a probe of the ground-state, one- electron properties of a solid. A. Shukla (ESRF-Grenoble) et al. have used this technique to compare the electron momentum density in PrBa2Cu3O7-d and YBa2Cu3O7-d, since PrBa2Cu3O7-d is almost always insulating and YBa2Cu3O7-d is (for small d) always superconducting. The electron momentum densities in the two materials were found to differ in a striking way, in contrast to LDA-based calculations, which predict similar behavior for both. The authors conclude that disorder in the form of Pr substitutions on Ba sites is responsible for the observed effects. Using a combined strategy to minimize substitution disorder and avoid tetravalent Pr on the Ba site, the authors have succeeded (details of this work to be published elsewhere) in obtaining small flux-grown crystallites of PrBa2Cu3O7-d with a Tc of 90 K and a bulk Meissner effect. The oxygenation used for these samples was the same as for 90 K superconducting YBa2Cu3O7-d, suggesting that the doping is optimal for both PBCO and YBCO. When big enough samples of superconducting PrBa2Cu3O7-d become available, the authors expect that the oxygen ordering behavior and the electron momentum density will be similar to that in YBa2Cu3O7-d.
As reported by S. P. Athur (TCSUH) et al., conventional sintering in air does not seem to be a suitable process for producing the 123 phase in YbBa2Cu3O7-d (Yb-123). On the other hand, the authors found that a simple sintering process under a reduced oxygen partial pressure could be used to prepare nearly phase-pure Yb-123.
The pseudo-binary phase diagram between NdBa2Cu3Ox and Ba3Cu10O13, and the nucleation and growth of NdBa2Cu3Ox in air have been observed by D. K. Aswal (Shizuoka) et al. in-situ using high-temperature optical microscopy. The authors found that interface kinetics is the rate- limiting factor in the crystallization of Nd-123 crystals from high- temperature solutions, while solute diffusion is the rate-limiting factor in Nd-123 crystallization from a peritectic melt.
Bi Cuprates
As noted by W. Goldacker et al. (Forschungszentrum Karlsruhe), hysteresis losses and coupling losses, a main component of the ac losses in Bi-2223 tapes, can be reduced by enhancing the resistivity of the matrix material between the filaments and applying a filament twist. By alloying the Ag sheath with Au, the resistivity of the Ag sheath can be raised, but only by a factor of less than ten at 77 K. For this reason, the authors have used resistive SrCO3 barriers between Ag-sheathed Bi- 2223 monocores to achieve a greater enhancement of the transverse resistivity. The authors note that SrCO3 is a cheap, fine-grained, commercially available material, which withstands tape annealing, bonds well to Ag, and does not react with the superconductor.
A related paper by H. Eckelmann (Forschungszentrum Karlsruhe) et al. reports on the ac loss properties of 37-filament Bi-2223 tapes with a AgAu(8wt%) matrix and 19-filament tapes with SrCO3 barriers between the filaments. The authors report transport ac loss and magnetic ac loss measurements in parallel and perpendicular magnetic fields. Both kinds of tapes were also prepared with filament twists with a pitch less than 20 mm. In magnetic ac loss measurements, reduced ac losses due to decoupled filaments were observed for the twisted tapes with a resistive matrix in low parallel fields.
A preprint by M. R. Koblischka (Oslo) et al. reports magnetization measurements in a model structure, which exhibits a low-field peak in the magnetization at positive fields in decreasing external magnetic field, similar to the behavior that has been observed in Bi-2223 tapes.
The powder-in-tube method, which involves industrial processes such as wire drawing and rolling, has been widely used to fabricate Ag-clad Bi- 2223 tapes. A. N. Iyer (TCSUH) et al. report on experiments in which, instead of wire drawing, the silver billet was reduced in size by groove rolling. Improved current transport properties were found, which the authors attribute to the increase in the amount and texturing of 2223 grains and to the absence of microcracks.
A preprint by M. Lelovic (Pittsburgh) et al. reports on the properties of a Ag-sheathed Bi-2223 tape on which a YBa2Cu3O7-d (Y-123) thin film was deposited. Although the Y-123 film had a Tc ~~ 72 K and a broad transition region, the critical current density of the coated tape was higher than that of an uncoated tape at 20 K, 40 K, and 60 K in fields above about 2 kOe.
The properties of isothermal melt-processed Bi-2212/Ag tapes containing MgO and Al2O3 additions are reported by N. V. Vo et al. (Los Alamos). Critical current densities at 4 K in excess of 10^5 A/cm^2 were obtained in tapes melt-processed below 800^oC.
La2-xSrxCuO4
The out-of-plane magnetoresistance of single crystals of La2-xSrxCuO4 has been measured by N. E. Hussey (Cambridge) et al. over a wide doping range (0.09 <= x <= 0.25) with the field applied parallel and perpendicular to the CuO2 planes. The results suggest that the c-axis transport in La2-xSrxCuO4 is an incoherent process whereby the carriers undergo significant scattering within the plane before hopping to an adjacent layer.
Thin Films
A detailed study of the tunneling spectra of bicrystal grain-boundary junctions fabricated from the high-temperature superconductors (HTS) YBa2Cu3O7-d (YBCO), Bi2Sr2CaCu2O8+d (Bi-2212), La1.85Sr0.15CuO4 (LSCO), and Nd1.85Ce0.15CuO4-y (NCCO) has been carried out by L. Alff (Koeln) et al. In all experiments the tunneling direction was along the CuO2 planes. With the exception of NCCO, for all materials a pronounced zero-bias conductance peak (ZBCP) was observed, which decreases with increasing temperature and disappears at the critical temperature. The authors explain these results by the presence of a dominating d-wave symmetry of the order parameter, resulting in the formation of zero- energy Andreev bound states at surfaces and interfaces of HTS. The absence of a ZBCP for NCCO is consistent with a dominating s-wave symmetry of the pair potential in this material. The observed nonlinear shift of spectral weight to finite energies under a magnetic field is in qualitative agreement with recent theoretical predictions.
A variational formulation and an efficient numerical method have been derived by L. Prigozhin (Weizmann Institute and Ben-Gurion University) to determine the current-density and magnetic-field distributions and hysteretic magnetization curves for thin films in the critical state. The author uses this method to solve problems for various film shapes with either the Bean (Jc = constant) or Kim [Jc(B) = Jc(0)/(1 + |B|/B_0)] model for Jc(B).
The processing of YBCO films by decomposition of metal-trifluoroacetate precursors, and its application to the development of coated conductors has been investigated by S. Sathyamurthy and K. Salama (TCSUH). Pole- figure analysis of films deposited on (100) SrTiO3 and LaAlO3 single- crystal substrates showed that these films have a high degree of alignment with the substrate both out-of-plane (<0.5 degree) and in- plane (<1.5 degrees). These chemically derived films were also found to have critical current densities well above 5 x 10^5 A/cm^2 at 77 K for 0.5 micrometer thick films.
The design and testing of a new device for point-contact tunneling measurements in superconductors are described in a preprint by L. Ozyuzer (Argonne and IIT) et al. The insert is designed for use with a continuous flow cryostat which allows for a large range of sample temperatures from 1.5 K to room temperature. The use of nonmagnetic parts allows tunneling measurements to be performed in high magnetic fields.
Applications
High-temperature superconducting (HTS) single-flux-quantum (SFQ) digital circuit applications will require high-resistance HTS Josephson junctions. B. D. Hunt et al. (Northrop Grumman) have investigated the factors affecting the resistance of SNS edge junctions that use Co-doped YBCO as the normal-metal layer. The authors found that edge angle, base-electrode material, and deposition conditions of the normal metal and counterelectrode all have an effect on device resistance. Controlling these factors has enabled the fabrication of high-quality, high-resistance (~~1 ohm) SNS edge junctions with one-sigma I_c spreads down to 10% and with critical currents and I_cR_n products suitable for SFQ digital applications.
Improved structural and dielectric properties of nonlinear dielectric SrTiO3 thin films on LaAlO3 substrates have been accomplished by Q. X. Jia (Los Alamos) et al. by incorporating a homo-epitaxial LaAlO3 interlayer between the substrate and the dielectric film. With this interlayer, the quality factor of SrTiO3 films with superconducting YBa2Cu3O7-d electrodes on LaAlO3 substrates was improved by more than 50% at 4.2 GHz and 4 K. This improvement, combined with no change in nonlinearity, led to greater than a 50% enhancement of finesse factor (defined as the product of the quality factor and the fractional shift in the resonant frequency) for coplanar waveguide microwave resonators. The improvement was attributed to the reduced planar defect density in the SrTiO3 films as seen by transmission electron microscopy.
Theory
Analytic results for the polarizabilities chi(Q,omega) in the charge, spin, and current channels have been derived by H.-Y. Kee (Rutgers and Bell Labs) and C. M. Varma (Bell Labs) for two-dimensional s- and d-wave superconductors for large momentum transfer. The authors predict a collective mode in the charge channel for extremum vectors of the Fermi surface with energy below twice the maximum superconducting gap. Such modes are directly observable through inelastic x-ray or electron scattering. Scattering of single-particle excitations by these collective modes leads to several unusual features in the single- particle spectrum in the superconducting state which are seen in angle- resolved photoemission experiments.
The high-temperature series for the momentum distribution function n_k of the 2D t-J model has been calculated by W. O. Putikka (Cincinnati and Ohio State) et al. to twelfth order in the inverse temperature. By extrapolating the series to T = 0.2 J, the authors searched for a Fermi surface of the 2D t-J model. They found that three criteria for estimating the location of a Fermi surface violate Luttinger's theorem, implying that the t-J model does not have an adiabatic connection to a noninteracting model.
A mechanism for superconductivity suppression in stripe-correlated cuprates, based on pinning of the stripes by impurities such as Zn, is proposed by A. H. Castro Neto (UC-Riverside) and A. V. Balatsky (Los Alamos). The superfluid density is suppressed in the vicinity of the impurity because of the low-dimensional character of superfluid carriers on the stripes. The authors predict a critical impurity concentration z_c ~ Tc^2 and a linear Tc suppression by Zn doping.
The tunneling dynamics of dopant-induced hole polarons that are self- localized by electron-phonon coupling in a two-dimensional antiferromagnet have been studied by K. Yonemitsu (IMS, Okazaki) et al. The authors' treatment is based on a path-integral formulation of the adiabatic (Born-Oppenheimer) approximation, combined with many-body, tight-binding, instanton, constrained lattice dynamics, and many-body exact diagonalization techniques. The authors discuss the implications of their results for the doping-dependent isotope effect, pseudogap, and Tc of a superconducting polaron pair condensate, and they compare their results with observed properties of the high-Tc cuprates.
Using the scenario of a hybridized mixture of localized bipolarons and conduction electrons, J. Ranninger (Grenoble) and A. Romano (Salerno) demonstrate the simultaneous appearance of a pseudogap and strong incoherent contributions to the quasiparticle spectrum arising from phonon shake-off effects. This can be traced back to temporarily fluctuating local lattice deformations, giving rise to a double peak in the pair distribution function, which should be a key feature in testing the origin of the incoherent contributions recently seen in angle- resolved photoemission spectroscopy (ARPES).
The nonadiabatic electron-phonon corrections for superconducting pairing have been investigated by A. Perali et al. (Roma) for a specific tight- binding model corresponding to a 2D square lattice. The authors are thus able to investigate the role of various specific properties such as band filling, nesting effects, and a realistic Van Hove singularity on the superconducting effective pairing beyond Migdal's limit.
A preprint by P. Miller (Georgetown) et al. reports calculations of the effects of vertex corrections, a non-constant density of states, and a self-consistently determined phonon self-energy for the Holstein model on a 3D cubic lattice. The authors replace vertex corrections with a Coulomb pseudopotential mu*, adjusted to give the same Tc, and repeat the calculations to see which effects are a distinct feature of vertex corrections. While vertex corrections can cause significant changes in many properties (critical temperatures, isotope coefficients, superconducting gaps, free-energy differences, and thermodynamic critical fields), the changes can usually be well modeled by an appropriate Coulomb pseudopotential. The isotope coefficient, however, proves to be the quantity that most clearly shows effects of vertex corrections that cannot be mimicked by a mu[dot].
The superconducting transition in the attractive Hubbard model in two dimensions has been studied by J. R. Engelbrecht and A. Nazarenko (Boston) using the self-consistent T-matrix approximation. The authors demonstrate that for large system sizes, this approximate method produces XY critical scaling in the correlation length and pair susceptibility. For the parameters investigated, the critical regime is quite large, extending beyond five times T_[KTB]. The authors suggest that vortex-pair unbinding in the normal state may be relevant to pseudogap behavior in the underdoped cuprates.
As shown by M. Casas (Palma de Mallorca) et al., a simple model of a boson-fermion mixture of unpaired fermions plus linear-dispersion- relation Cooper pairs including pair-breaking effects leads to Bose- Einstein condensation for all dimensions greater than unity. The Bose- Einstein critical temperatures are substantially greater than those of the BCS theory of superconductivity for the same BCS model interaction between the fermions.
To examine the mixed s+-id pairing state of high-Tc superconductors, S. Sergeenkov (JINR-Dubna) calculated the differential thermopower [Delta]S of an SND junction in the presence of strong charge-imbalance effects (due to a difference between the quasiparticle mu_q and Cooper-pair mu_p chemical potentials) using the generalized Ginzburg-Landau theory for a homogeneous admixture of s-wave and d-wave superconductors near Tc. The calculated thermopower was found to strongly depend on the relative phase theta = phi_s - phi_d between the two superconductors, exhibiting a pronounced maximum near the mixed s+-id state with theta = +-pi/2.
The dynamic response to external currents of periodic arrays of Josephson junctions in a resistively and capacitively shunted junction model has been studied by F. Gibbons (Northeastern) et al. including full capacitance-matrix effects. The authors introduce three different models for the capacitance matrix and calculate the corresponding I-V characteristics for dc + ac currents. For two of the models, the authors find giant capacitive fractional steps in the I-V's, strongly dependent on the amount of screening involved. The authors show that these steps are not related to vortex oscillations but to localized screened phase locking of a few rows in the lattice.
The effect of thermal fluctuations on the behavior of a four-terminal SQUID has been investigated by R. de Bruyn Ouboter (Leiden) and A. N. Omelyanchouk (Kharkov). For some combinations of the control parameters, the four-terminal SQUID is in a bistable state with two magnetic flux values. The authors study switching between the two flux values by thermal noise or an applied transport current.
Time-reversal-violating processes in a p-wave superconductor have been analyzed by J. Goryo and K. Ishikawa (Hokkaido). The Landau-Ginzburg effective action has an induced T-violating term, which causes a mixing between the electric field and the magnetic field. The authors find that several T-violating electromagnetic phenomena are caused by this term, such as an unusual Meissner effect, a Hall effect without a magnetic field, and Faraday rotation without a magnetic field.
Other Activities
As shown by J. B. Kycia et al. (Northwestern), the superconducting transition temperature of high-quality single crystals of UPt3 can be varied systematically by annealing, revealing that the intrinsic transition temperature of UPt3 is 563+-5 mK. The suppression of the superconducting transition by defects is consistent with a modified Abrikosov-Gor'kov formula that includes anisotropic pairing, Fermi- surface anisotropy, and anisotropic scattering by defects.
The dynamical dielectric response of a one-dimensional, correlated insulator has been determined by R. Neudert (Dresden) et al. via electron energy-loss spectroscopy on Sr2CuO3 single crystals. Magnetic susceptibility measurements previously have shown that Sr2CuO3 can be regarded as an almost ideal realization of the 1D spin-1/2 antiferromagnetic Heisenberg model, which describes the magnetic excitations of a Mott-Hubbard insulator. The authors found that the observed momentum and energy dependence of the low-energy features, which correspond to collective transitions across the gap, are well described by an extended one-band Hubbard model with moderate nearest- neighbor Coulomb interaction strength. An exciton-like peak appears with increasing momentum transfer. The authors stress that these observations provide experimental evidence for spin-charge separation in the relevant excitations of this compound, as theoretically expected for the one-dimensional Hubbard model.
The response of a superconducting Pb0.82In0.18 slab to time-dependent steps in a parallel applied field has been investigated by H. Vasseur et al. (Ecole Normale Superieure). The authors found that the penetration of magnetic flux into the sample is impeded by surface pinning, but there are practically no observable effects of bulk pinning.
Overview
A review of NMR and NQR spectroscopies in the high-temperature superconductors (chiefly La2-xSrxCuO4, YBa2Cu3O6+x, and YBa2Cu4O8), emphasizing the differences in behavior relative to metals and conventional superconductors, has been prepared by A. Rigamonti et al. (Pavia). The authors also review NMR-NQR spectra and relaxation rates in two-dimensional quantum antiferromagnets (particularly La2CuO4) driven towards the superconducting state by charge doping. They discuss behavior in the normal state, including spin-gap opening and superconducting fluctuations, and they review information that has been obtained about the vortex lattice and flux-line dynamics from NMR line narrowing, T_1, and echo dephasing (334 refs.).
Thesis
A B.S. thesis by S. J. Smullin (Brown) reports an experimental study of the peak effect in 2H-NbSe2. The author found that thermally activated motion and dimensional crossover do not explain the physics of the vortex lattice in the peak region. However, collective pinning theory was found to describe the data at low fields, and the peak effect was found to occur within the predicted melting regime (34 refs.).
Contributed by John R. Clem
Contents: Preprints begin on page 6; Coming Events begin on page 10; Resources are on page 12; FYI is on page 12; and two figures showing HTCU Web usage are shown on page 13 (if you don't see a link for the figures at the end of this version of the newsletter, please look at the RTF or BINHQX versions).
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.
L. Alff, A. Beck, R. Gross, A. Marx, S. Kleefisch, Th. Bauch, H. Sato, M. Naito, and G. Koren, "Observation of Bound Surface States in Grain Boundary Junctions of High Temperature Superconductors." To be published in Phys. Rev. B. II. Physikalisches Institut, Universitaet zu Koeln, Zuelpicherstr. 77, D-50937 Koeln, GERMANY; e-mail alff@colorix.ph2.uni-koeln.de; preprint also available at cond- mat@xxx.lanl.gov (#9805162).
P. Ao and X.-M. Zhu, "Role of Impurities in Core Contribution to Vortex Friction." Department of Theoretical Physics, Umea University, S-901 87 Umea, SWEDEN. 67.40.Vs.
P. Ao and X.-M. Zhu, "Vortex Dynamics from BCS Theory." Department of Theoretical Physics, Umea University, S-901 87 Umea, SWEDEN.
D. K. Aswal, M. Shinmura, Y. Hayakawa, and M. Kumagawa, "In-Situ Observation of Melting/Dissolution, Nucleation and Growth of NdBa2Cu3Ox by High Temperature Optical Microscopy." Submitted to J. Crystal Growth. Research Institute of Electronics, Shizuoka University, 3-5-1 Johoku, Hamamatsu 432-8011, JAPAN; telephone +81 53 478 1338; telefax +81 53 478 1338; e-mail roaswal@eng.shizuoka.ac.jp. Key words: solution growth, phase diagram, high-temperature optical microscopy, NdBa2Cu3Ox. 81.10.Fq; 81.30.Bx; 74.72.Bk.
S. P. Athur, P. Putman, U. Balachandran, and K. Salama, "Phase Formation and Melt-Processing of Yb-123." Preprint #98:041; submitted to J. Supercond. 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: Yb-123, melt processing, phase formation, reduced oxygen partial pressure.
J. E. Berger, S. J. Smullin, W. L. Karlin, X. S. Ling, and D. E. Prober, "Equilibrium and Driven Vortex Phases in the Anomalous Peak Effect." Submitted to Phys. Rev. Lett. Contact X. S. Ling, Department of Physics, Brown University, Providence, RI 02912; e-mail xsling@brown.edu; preprint also available at cond-mat@xxx.lanl.gov (#9805087). 74.60.Ge; 64.60.Cn.
M. Casas, A. Rigo, M. de Llano, O. Rojo, and M. A. Solis, "Bose-Einstein Condensation with a BCS Model Interaction." To be published to Phys. Lett. A. Contact M. A. Solis, Instituto de Fisica, UNAM, 01000 Mexico DF, MEXICO; e-mail masolis@fenix.ifisicacu.unam.mx. Key words: Boson condensation, pairing. 05.30.Fk; 05.30.Jp; 64.90.+b.
A. H. Castro Neto and A. V. Balatsky, "Effect of Planar Impurities on the Superfluid Density of Striped Cuprates." Department of Physics, University of California, Riverside, CA 92521; e-mail neto@phyun6.ucr.edu; preprint also available at cond-mat@xxx.lanl.gov (#9805273). 74.20.Mn; 74.50.+r; 74.72.Dn; 74.80.Bj.
Vladimir Chechersky, Amar Nath, and R. J. Cava, "Direct Evidence for the Electronic Phase Inhomogeneity in HoNi2B2C." To be published in Physica C. Contact Amar Nath, Department of Chemistry, Drexel University, 32nd & Chestnut Streets, Philadelphia, PA 19104; telephone (215) 895-2638 or -2639; telefax (215) 895-1265; e-mail amar_nath@coasmail.drexel.edu. Key words: Mossbauer, intermetallic superconductor, structural distortion.
R. de Bruyn Ouboter and A. N. Omelyanchouk, "Four-Terminal SQUID: Magnetic Flux Switching in Bistable State and Noise." To be published in Physica B. Kamerlingh Onnes Laboratorium, Leiden University, P.O. Box 9506, 2300 RA Leiden, THE NETHERLANDS; A. N. Omelyanchouk's e-mail at National Academy of Sciences of Ukraine, Kharkov, is omelyan@rulgm0.leidenuniv.nl; preprint also available at cond- mat@xxx.lanl.gov (#9805109). Key words: Josephson junction, multiterminal, SQUID, thermal fluctuations.
H. Eckelmann, M. Quilitz, M. Oomen, M. Leghissa, and W. Goldacker, "ac Losses in Multifilamentary Bi(2223) Tapes with an Interfilamentary Resistive Carbonate Barrier." Submitted to the Proc. of the Int. Cryogenic Mater. Conf. (ICMC'98), Enschede, The Netherlands, May 10-13, 1998. Forschungszentrum Karlsruhe, Institut fuer Technische Physik, P.O. Box 3640, D-76021 Karlsruhe, GERMANY; telephone +49 7247 82 5341; telefax +49 7247 82 5398; e-mail hubert.eckelmann@itp.fzk.de. Key words: Bi(2223) tapes, ac losses, resistive barriers, interfilamentary coupling.
Jan R. Engelbrecht and Alexander Nazarenko, "Vortex-Pair Unbinding in the Normal State of Two-Dimensional, Short-Coherence-Length Superconductors." Department of Physics, Boston College, Chestnut Hill, MA 02167; Alexander Nazarenko's telephone (617) 552-0681; telefax (617) 552-8478; e-mail nazarenk@physics.bc.edu. 74.25.-q; 74.20.-z; 74.20.Mn; 74.25.Dw.
Andreas Erb, Alfred A. Manuel, Marc Dhalle, Frank Marti, Jean-Yves Genoud, Bernard Revaz, Alain Junod, Dharmavaram Vasumathi, Shoji Ishibashi, Abhay Shukla, Eric Walker, Oystein Fischer, Rene Fluekiger, Riccardo Pozzi, Mihael Mali, and Detlef Brinkmann, "Experimental Evidence for Fast Cluster Formation of Chain Oxygen Vacancies in YBa2Cu3O7-d Being at the Origin of the Fishtail Anomaly." Submitted to Phys. Rev. Lett. Departement de Physique de la Matiere Condensee, Universite de Geneve, 24 quai Ernest-Ansermet, CH-1211 Geneva 4, SWITZERLAND; Alfred A. Manuel's e-mail alfred.manuel@physics.unige.ch; preprint also available at cond-mat@xxx.lanl.gov (#9805222).
Matthias Eschrig, J. A. Sauls, and D. Rainer, "Electromagnetic Response of a Vortex in Layered Superconductors." Department of Physics and Astronomy, Northwestern University, Evanston, IL 60208; J. A. Saul's e- mail sauls@snowmass.phys.nwu.edu; preprint also available at cond- mat@xxx.lanl.gov (#9805299).
H. Fang and K. Ravi-Chandar, "Nanocrystalline Y-Ba-Cu-O Powder." Preprint #98:038; submitted to the Proc. of the 1998 Minerals, Metals, and Mater. Soc. Mtg., San Antonio, TX, Feb. 15-19, 1998; to be published in J. Supercond. 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: high-energy ball milling, Y-Ba-Cu-O, melt texturing, phase change.
Frank Gibbons, A. Gongora-T., and Jorge V. Jose, "Full Capacitance- Matrix Effects in Driven Josephson-Junction Arrays." To be published in Phys. Rev. B (in press). Department of Physics and Center for Interdisciplinary Research on Complex Systems, Northeastern University, Boston, MA 02115; Jorge V. Jose's e-mail jose@citlalli7.physics.neu.edu; preprint also available at cond-mat@xxx.lanl.gov (#9805310). 74.50.+r; 74.60.Jg.
W. Goldacker, M. Quilitz, B. Obst, and H. Eckelmann, "Reduction of ac Losses Applying Novel Resistive Interfilamentary Carbonate Barriers in Multifilamentary Bi(2223) Tapes." Submitted to the Proc. of the Int. Cryogenic Mater. Conf. (ICMC'98), Enschede, The Netherlands, May 10-13, 1998; to be published in Physica C. Forschungszentrum Karlsruhe, Institut fuer Technische Physik, P.O. Box 3640, D-76021 Karlsruhe, GERMANY; telephone +49 7247 82 4179; telefax +49 7247 82 5398; e-mail wilfried.goldacker@itp.fzk.de. BSCCO tape, resistive barrier, strontium carbonate, ac loss.
Jun Goryo and Kenzo Ishikawa, "E-B Mixing in T-Violating Superconductors." Submitted to J. Phys. Soc. Jpn. High Energy Physics Theory Group, Faculty of Science, Department of Physics, Hokkaido University, Sapporo 060-0810, JAPAN; telephone +81 11 706 3438; telefax +81 11 706 3438; e-mail goryo@particle.sci.hokudai.ac.jp; preprint also available at cond-mat@xxx.lanl.gov (#9805140). Key words: time- reversal violation, p-wave superconductor, Chern-Simons term, Meissner effect, Hall current, magnetic moment.
Brian D. Hunt, Martin G. Forrester, John Talvacchio, and Robert M. Young, "High-Resistance HTS SNS Edge Junctions." To be published in Applied Supercond. (in press). Northrop Grumman Science and Technology Center, Pittsburgh, PA 15235.
N. E. Hussey, J. R. Cooper, Y. Kodama, and Y. Nishihara, "Out-of-Plane Magnetoresistance of La2-xSrxCuO4: Evidence for Intraplanar Scattering in the c-Axis Transport." To be published in Phys. Rev. B. Institute for Solid State Physics, University of Tokyo, 7-22-1 Roppongi, Minato- ku, Tokyo 106, JAPAN; telephone +81 3 3478 6811, ext. 5663; telefax +81 3 3478 7698; e-mail nehussey@troy.issp.u-tokyo.ac.jp. 74.25.Fy; 74.72.Dn.
M. N. Iliev, A. P. Litvinchuk, H. G. Lee, C. L. Chen, L. M. Dezaneti, C. W. Chu, V. G. Ivanov, M. V. Abrashev, and V. N. Popov, "Raman Spectroscopy of SrRuO3 Near the Paramagnetic-to-Ferromagnetic Phase Transtition." Preprint #98:044; submitted to 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.
A. N. Iyer, S. Salib, M. K. Mironova, C. Vipulanandan, U. Balachandran, and K. Salama, "Fabrication and Electrochemical Characterization of Silver-Clad BSCCO Tapes." Preprint #98:042; submitted to J. Supercond. 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: groove rolling, powder-in-tube technique, BSCCO, current transport properties, phase development, in- situ tensile test, strain tolerance.
Q. X. Jia, A. T. Findikoglu, D. Reagor, and P. Lu, "Improvement in Performance of Electrically Tunable Devices Based on Nonlinear Dielectric SrTiO3 Using Homo-Epitaxial LaAlO3 Interlayer." Preprint #LA-UR-98-2075; 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.
M. Kaell, M. Osada, M. Kakihana, L. Boerjesson, T. Frello, J. Madsen, N. H. Andersen, R. Liang, P. Dosanjh, and W. N. Hardy, "CuO-Chain Raman Scattering and Photoinduced Metastability in YBa2Cu3Ox." To be published in Phys. Rev. B. Department of Applied Physics, Chalmers University of Technology, S-412 96 Goeteborg, SWEDEN; L. Boerjesson's telephone +46 31 772 3307; telefax +46 31 772 2090; e-mail borje@fy.chalmers.se. 74.25.Kc; 63.20.Mt; 74.72.Bk; 78.30.Er.
Hae-Young Kee and C. M. Varma, "Polarizability and Single Particle Spectra of Two-Dimensional s- and d-Wave Superconductors." Department of Physics, Rutgers University, Piscataway, NJ 08855-0849; e-mail hykee@physics.rutgers.edu; preprint also available at cond- mat@xxx.lanl.gov (#9806006). 74.20.-z; 74.20.Fg; 74.25.Nf.
M. R. Koblischka, L. Pust, A. Galkin, P. Nalevka, M. Jirsa, T. H. Johansen, H. Bratsberg, B. Nilsson, and T. Claeson, "Modeling the Anomalous Low Field Peak Position in Bi-2223 Tapes." To be published in Phys. Status Solidi A. Superconductivity Research Laboratory, International Superconductivity Technology Center (ISTEC), 1-16-25 Shibaura, Minato-ku, Tokyo 105, JAPAN; telephone +81 3 3454 9284; telefax +81 3 3454 9287; e-mail koblischka@istec.or.jp.
N. B. Kopnin and V. M. Vinokur, "Dynamic Vortex Mass in Clean Fermi Superfluids and Superconductors." Submitted to Phys. Rev. Lett. L. D. Landau Institute for Theoretical Physics, 117940 Moscow, RUSSIA; V. M. Vinokur's e-mail at Argonne National Laboratory vinokur@msd.anl.gov; preprint also available at cond-mat@xxx.lanl.gov (#9806065). 74.20.-z; 74.60.Ge; 74.60.-w; 67.40.Vs; 67.57.Fg.
J. B. Kycia, J. I. Hong, M. J. Graf, J. A. Sauls, D. N. Seidman, and W. P. Halperin, "Suppression of Superconductivity in UPt3 Single Crystals." To be published in Phys. Rev. B. Department of Physics and Astronomy, Northwestern University, Evanston, IL 60208; J. A. Saul's e-mail sauls@snowmass.phys.nwu.edu.
M. Lelovic, N. G. Eror, U. Balachandran, B. Prorok, V. Selvamanickam, P. Haldar, J. Talvacchio, and R. Young, "Shielded High-Tc (Bi,Pb)2Sr2Ca2Cu3Oy (Bi-2223) Superconducting Tapes." Submitted to Supercond. Sci. & Technol. Department of Materials Science, University of Pittsburgh, Pittsburgh, PA 15261.
J. Martin, R. P. Huebener, J. B. le Grand, C. A. Mears, S. E. Labov, and A. T. Barfknecht, "Imaging of Vortices in Superconductors by Electron Beam Scanning." To be published in Appl. Phys. Lett. Experimental Physik II, Universitaet Tuebingen, Auf der Morgenstelle 14, D-72076 Tuebingen, GERMANY; telephone +49 7071 29 76320; telefax +49 7071 29 5406; R. P. Huebener's e-mail prof.huebener@uni-tuebingen.de. 85.25.Cp; 07.85.Fv; 74.25.Ha.
P. Miller, J. K. Freericks, and E. J. Nicol, "What Are the Experimentally Observable Effects of Vertex Corrections in Superconductors?" Department of Physics, Georgetown University, Washington, DC 20057-0995; e-mail miller@physics.georgetown.edu; preprint also available at cond-mat@xxx.lanl.gov (#9805254).
J. Mosqueira, J. A. Campa, A. Maignan, I. Rasines, A. Revcolevschi, C. Torron, J. A. Veira, and Felix Vidal, "The Intrinsic Crossing Point of the Magnetization Versus Temperature Curves in Superconducting Cuprates in the High Magnetic Field Limit." To be published in Europhys. Lett. Laboratorio de Bajas Temperaturas y Superconductividad, Departamento de Fisica de la Materia Condensada, Universidad de Santiago de Compostela, E-15706 Santiago de Compostela, SPAIN. 74.25.Ha; 74.40.+k; 74.72.-h.
R. Neudert, M. Knupfer, M. S. Golden, J. Fink, W. Stephan, K. Penc, N. Motoyama, H. Eisaki, and S. Uchida, "Manifestation of Spin-Charge Separation in the Dynamic Dielectric Response of One-Dimensional Sr2CuO3." To be published in Phys. Rev. Lett. Institut fuer Festkoerper- und Werkstofforschung Dresden, P.O. Box 270016, D-01171 Dresden, GERMANY; telephone +49 351 4659 548; telefax +49 351 4659 537; e-mail neudert@ifw-dresden.de. 71.27.+a; 71.45.Gm; 71.10.Fd.
F. Onufrieva and P. Pfeuty, "Electronic Topological Transition in 2D Electron System on a Square Lattice and the Line T*(d) in the Underdoped Regime of High-Tc Cuprates." Submitted to Phys. Rev. B. Laboratoire Leon Brillouin, CE-Saclay, F-91191 Gif-sur-Yvette, FRANCE; e-mail onufri@11b.saclay.cea.fr; preprint also available at cond- mat@xxx.lanl.gov (#9804191).
L. Ozyuzer, J. F. Zasadzinski, and K. E. Gray, "Point Contact Tunneling Apparatus with Temperature and Magnetic Field Control." Submitted to Cryogenics. Contact Janice Coble, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439; telefax (708) 252-9595; e-mail janice_coble@qmgate.anl.gov. Key words: tunneling spectroscopy, superconductors, cryostat.
A. Perali, C. Grimaldi, and L. Pietronero, "Nonadiabatic Pairing Effects for Tight-Binding Electrons Interacting with Phonons." To be published in Phys. Rev. B. Department of Physics, University of Rome "La Sapienza", Piazzale A. Moro 2, I-00185 Rome, ITALY; C. Grimaldi's telephone +39 6 4991 3450; telefax +39 6 446 3158; e-mail claudio@pil.phys.uniroma1.it; preprint also available at cond- mat@xxx.lanl.gov (#9805041). 74.20.Mn; 71.38.+i; 63.20.Kr.
Leonid Prigozhin, "Solution of Thin Film Magnetization Problems in Type- II Superconductivity." To be published in J. Comp. Phys. CEEP, Blaustein Institute for Desert Research, Ben-Gurion University, Sede Boker Campus, 84990 Sede Boker, ISRAEL; e-mail leonid@bgumail.bgu.ac.il.
W. O. Putikka, M. U. Luchini, and R.R.P. Singh, "Violation of Luttinger's Theorem in the Two-Dimensional t-J Model." Submitted to Phys. Rev. Lett. Department of Physics, Ohio State University, Mansfield, OH 44906; preprint also available at cond-mat@xxx.lanl.gov (#9803140).
J. Ranninger and A. Romano, "Interrelation Between the Pseudogap and the Incoherent Quasi-Particle Features of High-Tc Superconductors." To be published in Phys. Rev. Lett. Centre de Recherches sur les Tres Basses Temperatures, Laboratoire Associe a l'Universite Joseph Fourier, CNRS, B.P. 166, F-38042 Grenoble Cedex 9, FRANCE; A. Romano's e-mail at Universita di Salerno alforom@vaxsa.csied.unisa.it. 79.60.-i; 74.20.Mn; 71.38.+i.
Bernard Revaz, Alain Junod, and Andreas Erb, "Specific Heat Peaks Observed up to 16 Teslas on the Melting Line of Vortex Matter in DyBa2Cu3O7." Submitted to Phys. Rev. Lett. Departement de Physique de la Matiere Condensee, Universite de Geneve, 24 quai Ernest-Ansermet, CH- 1211 Geneve 4, SWITZERLAND; Alain Junod's telephone +41 22 702 6204; telefax +41 22 702 6869; e-mail alain.junod@physics.unige.ch. 74.25.Bt; 74.25.Ha; 74.60.Ge; 74.72.Jt.
A. Rigamonti, F. Borsa, and P. Carretta, "Basic Aspects and Main Results of NMR-NQR Spectroscopies in High Temperature Superconductors." To be published in Reports on Progress in Physics. Department of Physics "A. Volta," Unita' INFM and Sezione INFN di Pavia, Via Bassi 6, I-27100 Pavia, ITALY; telephone +39 382 507-471 or -474; telefax +39 382 507- 563; e-mail rigamonti@pv.infn.it.
Seungoh Ryu and David Stroud, "Nature of the Low Field Transition in the Mixed State of High Temperature Superconductors." To be published in Phys. Rev. B. Schlumberger-Doll Research, Old Quarry Road, Ridgefield, CT 06877; e-mail ryu@ridgefield.sdr.slb.com.
S. Sathyamurthy and K. Salama, "Processing of Y1Ba2Cu3Ox Films by Solution Techniques Using Metal Organic Decomposition." Preprint #98:043; submitted to J. Supercond. 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: MOD, YBCO films, coated conductors, solution deposition.
Sergei A. Sergeenkov, "Probing Mixed s+-id Pairing State via Thermoelectric Response of SND Junction." Presented at the NATO Advanced Research Workshop on Symmetry and Pairing in Superconductors, Yalta, Crimea, Ukraine, April 28-May 2, 1998; to be published in NATO ASI Series. Bogoliubov Laboratory of Theoretical Physics, Joint Institute for Nuclear Research, 141980 Dubna, Moscow Region, RUSSIA; e- mail ssa@thsun1.jinr.dubna.su; preprint also available at cond- mat@xxx.lanl.gov (#9805389).
Abhay Shukla, Bernardo Barbiellini, Andreas Erb, Alfred Manuel, Thomas Buslaps, Veijo Honkimaeki, and Pekka Suortti, "Insulating PrBa2Cu3O7-d and Superconducting YBa2Cu3O7-d: Charge Transfer Modified by Disorder." Submitted to Phys. Rev. Lett. European Synchrotron Radiation Facility, BP 220, F-38043 Grenoble, FRANCE; Alfred Manuel's e-mail at Universite de Geneve alfred.manuel@physics.unige.ch; preprint also available at cond-mat@xxx.lanl.gov (#9805225). 74.72.Jt; 74.72.Bk; 74.62.Dh; 78.70.Ck.
Sylvia J. Smullin, "The Peak Effect and the Physics of Vortex Matter." Submitted as a Physics Sc.B. thesis (Brown University). Department of Physics, Brown University, Providence, RI 02912.
B. Suresh, "Rigid Approximation of Van Hove Singularity (vHs) by Quantum Numbers in Superconducting Cuprate Oxides." Submitted to Physica C. BHEL MIG 1141, R.C. Puram, Hyderabad 500032, A.P. INDIA; telephone +91 40 3022816; e-mail sur@supernews.com.
Zlatko Tesanovic, "Extreme Type-II Superconductors in a Magnetic Field: A Theory of Critical Fluctuations." Submitted to Phys. Rev. B. Department of Physics and Astronomy, Johns Hopkins University, Bloomberg Center, Baltimore, MD 21218; telephone (410) 516-5391; telefax (410) 516-7239; e-mail zbt@pha.jhu.edu; preprint also available at cond- mat@xxx.lanl.gov (#9801306). 74.40.+k; 74.25.Bt; 74.20.De; 74.25.Dw; 74.25.Ha; 74.60.Ec.
H. Vasseur, P. Mathieu, B. Placais, and Y. Simon, "Magnetic-Field Step Response of a Type-II Superconductor as a Simple Test of the Vortex Bulk Pinning." Submitted to J. Phys.: Cond. Mat. Laboratoire de Physique de la Matiere Condensee de l'Ecole Normale Superieure, 24 rue Lhomond, F- 75231 Paris Cedex 5, FRANCE. 74.60.Ge; 74.25.Nf.
N. V. Vo, T. G. Holesinger, P. S. Baldonado, and W. L. Hults, "Isothermal Melt Processed Bi-2212/Ag Tapes Containing MgO and Al2O3 Additions." Preprint #LA-UR-98-2265; to be published in Phys. Rev. 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.
M. Willemin, C. Rossel, J. Hofer, H. Keller, and A. Erb, "Strong Shift of the Irreversibility Line in High-Tc Superconductors Upon Vortex Shaking with an Oscillating Magnetic Field." Submitted to Phys. Rev. B. IBM Research Division, Zurich Research Laboratory, Saeumerstrasse 4, CH- 8803 Rueschlikon, SWITZERLAND. 74.25.-q; 74.25.Ha; 74.72.Bk; 74.60.Ge.
K. Yonemitsu, J. Zhong, and H.-B. Schuettler, "Berry Phases and Pairing Symmetry in Holstein-Hubbard Polaron Systems." Department of Theoretical Studies, Institute for Molecular Science, Okazaki, Aichi 444-8585, JAPAN; e-mail kxy@ims.ac.jp; preprint also available at cond- mat@xxx.lanl.gov (#9805320). 74.72.-h; 71.38.+i; 75.10.Lp; 71.27.+a.
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, 420 Commonwealth Drive, Warrendale, PA 15086; telephone (724) 776-9000; telefax (724) 776-3770; Web site http://www.tms.org/meetings/specialty/emc98/emc98.html.
*June 29 - July 10, 1998: 1998 Summer Course on Superconducting Materials -- Advances in Technology and Applications, CNR Conference Centre, Bologna, Italy. Will focus on both HTS and LTS superconducting materials. Fundamental aspects, theory, and advances in materials synthesis, processing, and properties will be featured as well as current developments in superconducting components and devices. Particular emphasis will be placed on existing and potential applications of HTS superconductors. In addition to the official lectures, several seminars will be held by invited scientists. Director of Summer Course: K. Kitazawa (University of Tokyo, Japan). Course is open to all participants; however, attendance will be limited to about 70 students. Topics include HTS materials history and perspectives; chemical and structural aspects of superconducting phases; new classes of superconductors; physical properties and mechanisms of superconducting materials; dissipative properties and ac losses; synthesis methodologies; bulk materials and thick films; thin films and multilayers; tapes and wires; relationships between process parameters and functional properties; main characterization techniques for materials and performances; medical applications; large-scale applications such as energy production, magnets, motors, magnetic energy storage, accelerator technology, and space applications; and small-scale applications including passive (microwave resonators and filters) and active devices (Josephson junctions and circuits, detectors, and sensors). For further information, contact Anna Tampieri, Scientific secretary, IRTEC-CNR, via Granarolo 64, I-48018 Faenza, Italy; telephone +39 546 699 757; telefax +39 546 46 381; e-mail superconductors@irtec1.irtec.bo.cnr.it; Web site http://area.bo.cnr.it/ldavinci.
July 20 - 22, 1998: 1998 DOE Superconductivity Program Annual Peer Review, Loews L'Enfant Plaza Hotel, Washington, DC. Will consist of concurrent sessions evaluating HTS wire and systems projects being undertaken at six national laboratories. Open to the public. Panels of experts will provide scores and written comments. An additional workshop will be held after the review on July 22, to discuss the suitability of existing cryogenic systems for HTS electric power equipment as commercialization gets closer. For more info call Audrey Lamanna at Energetics, Inc.; telephone (202) 479-2748; e-mail alamanna@energeticsinc.com.
*Sept. 14 - 25, 1998: NATO Advanced Study Institute -- Material Science, Fundamental Properties and Future Electronic Applications of High-Tc Superconductors, Albena, Bulgaria. Purpose is to help young physicists in their initial research in the field of HTS and related topics, and to support creation of the atmosphere of collaboration between physicists from NATO and Cooperative Partner countries. Aimed at scientists at the postdoctoral level with an appropriate scientific background. Subjects include: electronic structure of novel superconductors and related materials, Fermi surface mapping by angle- resolved photoemission, d-wave superconductivity, application of Eliashberg theory, and anomalous normal-state properties of HTS. Special attention will be paid to classical problems in the physics of superconductivity: Ginzburg-Landau and London theories and their application to theory of plasma waves in superconducting systems, surface phase transitions, hydrodynamic relations for superconductors, dynamics and pinning of vortices in HTS, electrodynamics, magnetic susceptibility, optical properties, tunneling, and fluctuation phenomena in superconductors. Will also include phenomenology of superconductivity: practical applications, superconducting field effect transistors, electric field effects in superconductors, and grain boundary and other material effects. Application deadline, June 15, 1998. For information, contact T. Mishonov, Department of Theoretical Physics, Faculty of Physics, University of Sofia, 5, J. Bourchier Blvd., 1164 Sofia, Bulgaria; telephone +359 2 256 652; telefax +359 2 96 252 76; e-mail mishonov@rose.phys.uni-sofia.bg. Note new application deadline.
Jan. 7 - 13, 1999: 1999 University of Miami Conference on High Temperature Superconductivity, Miami, Fla. Third in the series. Goal of this conference is to provide a forum for engaging researchers in a focused dialog directed at exploring and distilling the latest experimental and theoretical results in the field likely to have significant influence on the understanding of the normal-state properties and origin of superconductivity in this class of materials. The format will involve a relatively small number (150) of researchers assembled in common sessions. The conference, in addition to addressing physical properties, microscopic theory, and mechanisms for high- temperature superconductivity, will include other related topics (e.g. ladders, manganites, and nickelates). Partial list of topics for which abstracts are solicited includes: pseudogap, stripes/AF correlations, gap symmetry/tunneling, vortex properties, electronic structure, photoemission, non-Fermi liquids, mechanisms, new materials, other oxides (Mn, Ni, etc.), and ladder compounds. Abstract deadline, October 2, 1998. Contributed presentations will primarily be in the form of posters, although a small number may be selected for oral presentation. For information contact HTS99@physics.miami.edu. Further details are available on the world-wide web at http://www.miami.edu/physics/hts99.
Aug. 4 - 11, 1999: 22nd International Conference on Low Temperature Physics (LT22), Espoo and Helsinki, Finland. Topics will include: quantum gases, fluids and solids; superconductivity; magnetism and lattice properties; quantum electron transport; applications; materials; and techniques. For information, contact Conference Service Bureau, TSG-Congress Ltd., Kaisaniemenkatu 3 B 31, FIN-00100 Helsinki, Finland; telephone +358 9 628044; telefax +358 9 667675; e-mail info@tsgcongress.fi. For technical information, contact the LT22 Office, Low Temperature Laboratory, Helsinki University of Technology, P.O. Box 2200, FIN-02015 HUT; telephone +358 9 451 2962; telefax +358 9 451 2969; e-mail info@LT22.hut.fi.
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New Book: Superconductivity, by John Boyd Ketterson and Shengian Song. Text focuses on the underlying theory of superconductivity. First part of the book, which treats phenomenological theories, is suitable for students with an undergraduate degree in physics. Parts II and III, which make use of second quantization, are suitable for students who have completed a year of graduate school. Aimed at students and researchers in the field wishing to have a deeper understanding of the theory of superconductivity. Part I covers London, Pippard, and Ginzburg-Landau theories; Part II discusses the BCS theory; and Part III treats nonuniform superconductors using the Bogoliubov-de Gennes approach. Publ. 1998; 425 pp.; price $68 (hardcover) or $27.97 (paperback); ISBN 0-521-56295-3 (HC) or 0-521-56562-6 (PB). Contact Customer Service Department, Cambridge University Press, 110 Midland Avenue, Port Chester, NY 10573; telephone (800) 872-7423; telefax (914) 937-4712; e-mail orders@cup.org; Web site http://www.cup.org.
Products and Services
High-quality Bi-2223 tapes produced by the powder-in-tube method are available from BICC Cables. The Cryobicc[TM] tapes are fabricated in a wide range of properties and can be adjusted to meet specific customer requirements. For information, contact BICC Cables Limited, Wrexham Technology Centre, Superconductivity Group, Wrexham, Wales LL13 9XP, United Kingdom; telephone +44 1978 662518; telefax +44 1978 662464; e- mail cryobicc@bicc.co.uk.
FYI (High-Tc Update takes no responsibility for want ads listed in this section.)
Positions Open: The Superconductivity Group of BICC Cables, a commercial supplier of Bi-2223 tapes that also undertakes R&D in HTS products, including current leads, coils, and cable systems, seeks to fill the following positions:
Senior Scientist/Engineer: An experienced person to be responsible for the technical development of HTS tapes and devices and assist with their commercialization. The ideal candidate for this post will have a Ph.D. and several years' experience in either the materials, engineering, or physics aspects of BSCCO and will have a working knowledge of others. This will have been gained in an international context at renowned academic or industrial institutions and will have led to several publications in reputable scientific journals. Candidates will have a proven ability to communicate effectively in English and a second language would be an advantage. Candidates will also be able to demonstrate excellent interpersonal skills and will already possess project management and team leadership skills or have the potential to rapidly acquire them.
Materials Scientist: The post includes leading the development of our Bi-2223 tape technology and designing solutions to suit our customers' needs. The ideal candidate for this post will have gained a Ph.D. or have post-doctoral experience in the processing of Bi-2223 tapes or a closely related field. A hands-on attitude is required as well as the ability to work as part of a team. Candidates will display a good command of English or show the willingness to learn the language. A good publication record is desirable or the ability to establish one should be demonstrated.
Mechanical Engineer: The successful candidate will design, build and test products for mechanical, electrical, and thermal properties. He or she will liaise with the senior scientists responsible for product development and will also assist with customers' inquiries. Another important aspect of the job concerns developing new cabling machines and helping to maintain and improve the Group's extensive existing plant. The ideal candidate will already have, or be soon expected to complete, a mechanical engineering degree or equivalent level. A hands-on approach is essential, as well as the ability to work as part of a team. The Group has a commitment to innovation and will expect the successful candidate to show a flexible attitude to project work. Candidates will also be expected to have a working knowledge of cryogenic systems. Some experience of vacuum systems and Autocad is preferable but not essential.
All three posts are based in the North-West of England. The positions are permanent. BICC Cables offers a competitive salary and comprehensive benefits. All positions are available immediately and candidates are encouraged to send a cover letter and CV (Word for Windows 6.0 if possible) to Luc Le Lay, BICC Cables Limited, Energy Technology, WREXHAM LL13 9XP, United Kingdom; telephone +44 1978 66 2600; telefax +44 1978 66 2464; e-mail uclelay@bicc.co.uk.
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, #12, June 15, 1998.