Symmetry and Pairing in Superconductors

These Proceedings of a NATO-ARW (HTECH ARW 97 1843) held at the Oreanda Hotel, Yalta, Ukraine from April 29 till May 2 , 1998 resulted from many discussions between various workers, concerning the need for a gathering of all (if possible) who were concerned with the subject of symmetry of the order parameter and pairing states for superconductivity. We applied ourselves in particular to High critical Temperature Superconductors (HTS), but also studied other unconventional superconductors. The study of HTS is one of the most prominent research subjects in solid state sciences. The understanding of the role of symmetry and pairing conditions are also thought to be necessary before technological applications since these features may be influenced by external fields. The workshop discussions have touched upon theoretical and experimental aspects, but also on related topics. These served as initiators for a very great amount of discussions with many comments from the audience. More than thirty "long lectures" and one on going "poster session" were held. Private discussions went unrecorded but obviously took place at many locations : lecture halls, staircases, cafes, bedrooms, bars, beach,bus, plane... Arguments openly reported for the first time were often quite sharp ones, -and this is an understatement.

Zusammenfassung
Proceedings of the NATO Advanced Research Workshop, Yalta, Ukraine, April 29-May 2, 1998

Inhalt
I. Apparently considered to be more theoretical ....- Day of unconventional superconductors.- Tunneling spectroscopy of the heavy electron superconductor UBe13.- Influence of inelastic quasiparticle scattering on thermodynamic and transport properties of high-temperature oxides.- Anisotropic 3D fluctuation conductivity in Y1Ba2Cu3O7-y thin films.- Quantum Monte Carlo simulations of the two-dimensional attractive Hubbard Model: phase diagram and spectral properties.- Rhombic vortex lattice in d-Wave superconductivity.- Pseudogaps and magnetic properties of the t-J model.- Probing s±id pairing state via thermoelectric response of SND junction.- Generalized BCS-type model for the acoustic plasmon induced D-wave superconductivity.- Spin fluctuation pairing in the t-J model.- Charge density fluctuations and gap symmetry in High- Tc superconductors with extended sadle-point features in electron spectrum.- Vortex lattice melting theories as an example of science fiction.- Numerical simulation of flux-creep in presence of a pinning strength distribution for the washboard-type potential.- Electric field effects in High- Tc cuprates with different bulk and surface conductivities.- The orbital symmetry of the order parameter in HTSC: The controversy continues.- Dynamic axial charge transfer processes in La2-xSrxCuO4.- Coexistence of superconductivity with charge- or spin- density waves.- Instability of a 2-dimensional Landau-Fermi liquid due to Umklapp scattering.- Momentum broadening in the interlayer pair-tunneling model of High Tc superconductivity.- Effects of Van Hove singularities on thermal properties of high Tc superconductors.- Mean free path effects on the electronic Raman spectra of d-wave superconductors.- s- and d-wave pairing in short coherencelengthsuperconductors.- k-space gap anisotropy within the interlayer pair-tunneling mechanism of high-Tc superconductivity.- II.... than experimental.....- Point-contact spectroscopy of superconducting RNi2B2C (R=Rare earth, Y).- Theory and experimental evidence for pair FQHE state caused by zero-point harmonic oscillation in block-layer potential (abstract).- Different estimates of the anisotropy from resistive measurements in high Tc superconductors.- Vortex lattice melting and viscosity in Y0.3Dy0.4Ba2Cu3O7-x superconductor studied by electrical resistivity.- Is fluctuation conductivity a probe to determine the presence of s- or d-wave pairing in High Tc superconductors ?.- Pseudo-gap and crossover from the 2D Heisenberg to the even-leg spin-ladder regime in underdoped cuprates.- The influence of grain boundary roughness on tricrystal symmertry tests.- Localized cluster states studied by EPR in R123 compounds.- Fluctuation contributions to the transport properties of Hg1.4Ba2Ca2Cu3O8+? and Bi2Sr1.8Ca1.2Cu2O8 polycrystalline superconductors.- III. ....with respect to other reports..- Transformation of thermal energy into electric energy in an inhomogeneous superconducting ring.- Phase transition related with' Spin Density Lattice' in TbNiSn.- quote from The innocents abroad (1869) by Mark Twain.- late submission.- Theory and experimental evidence for pair FQHE state caused by zero-point harmonic oscillation in block-layer potential.- Keyword Index.