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NOTA BENE:
Dear Subscribers: As you know, High-Tc Update will cease publication sometime within the next few months. (The date of the last issue will depend mainly on our staffing situation. We will let you know as soon as a decision is made.) Here are a few information resources that may be helpful to you in our absence:
Condensed Matter e-print archive (cond-mat) at Los Alamos National Laboratory http://xxx.lanl.gov/list/\cond-mat.supr-con/recent and related links.
Electrotechnical Laboratory (ETL) Superconductivity Papers Database http://www.aist.go.jp/RIODB/sprcnd_etl/.
We will, in the next few weeks, try to find a few more resources that can help our readers. If any of you know of a Web site or resource that HTCU readers may find useful, please let us know and we will print it in the newsletter.
Vortices
The upper and lower critical points in untwinned YBa2Cu3O7-d single crystals with dilute columnar defects have been investigated by W. K. Kwok (Argonne) et al. Dilute columnar defects were found to raise the upper critical point, indicating that the transition near the upper critical point is a vortex-entanglement transition. The lower critical point was found to be very sensitive to columnar-defect disorder, and its position can be described by a Lindemann-like criterion similar to that used for melting. The authors found that dilute columnar defects induce nonlinear behavior in the I-V curves of the vortex-liquid state above the lower critical point, which is interpreted as a vestige of the critical region associated with the Bose-glass transition below the lower critical point.
A related paper by G. W. Crabtree (Argonne) et al. reports the differing effects of line and point disorder upon the upper and lower critical points in the (H-T) vortex phase diagram of YBa2Cu3O7-d. The authors found that dilute line disorder induces a Bose-glass transition at low fields, which is replaced at the lower critical point by first-order melting at higher fields. The upper critical point is lowered by point disorder but raised by line disorder.
Using an ac technique, M. Konczykowski (Ecole Polytechnique) et al. have investigated the first-order phase transition in the vortex lattice in Bi2Sr2CaCu2O8+d (Bi-2212) by independently varying the dc magnetic field perpendicular (H_[perp.]) and parallel (H_[parallel]) to the layers. The authors thus independently controlled the density of 2D pancake and Josephson vortices. The authors found at least two distinct regions in the vortex-solid phase, and they show corresponding phase diagrams in the H_[perp.]-H_[parallel] plane at different temperatures.
A preprint by C. Reichhardt (UC-Davis) et al. points out several recent experimental and numerical observations that are at odds with the vortex-glass theory of the freezing of disordered vortex matter. To investigate this issue, the authors performed numerical simulations of the overdamped London-Langevin model and used finite-size scaling to analyze their results. The authors found that upon approaching the transition, the initial vortex-glass criticality is arrested at a crossover temperature. Below this temperature, the time scales continue to grow rapidly, consistent with the Vogel-Fulcher form, while the spatial correlation length xi stops exhibiting any observable divergence. The authors call this mode of freezing the vortex-molasses scenario.
Two preprints by C. J. van der Beek (Ecole Polytechnique) et al. report time-resolved local induction measurements near the vortex-lattice order-disorder transition in optimally doped Bi2Sr2CaCu2O8+d (Bi-2212) crystals. The results show that the high-field disordered phase can be quenched to fields as low as half the transition field. The authors interpret the results in terms of supercooling of the high-field phase and the possible first-order nature of the order-disorder transition at the second magnetization peak.
Using numerical simulations, C. J. Olson and C. Reichhardt (UC-Davis) have investigated the transverse depinning of moving vortex lattices interacting with random disorder. When the vortex lattice is defect- free and moving in correlated one-dimensional channels under the influence of a high longitudinal drive, a finite transverse depinning barrier for vortex lattices is observed. However, when the longitudinal drive is decreased and defects appear in the vortex lattice, the barrier is found to disappear in the plastic-flow regime. The authors found that at the transverse depinning transition, the vortex lattice moves in a staircase pattern with a clear transverse narrow-band voltage-noise signature.
A preprint by M. C. Marchetti et al. (Syracuse) reports an investigation of the mean-field dynamics of an overdamped viscoelastic medium driven through quenched disorder. The authors' model incorporates coexistence of pinned and sliding degrees of freedom and can exhibit continuous elastic depinning or first-order hysteretic depinning. Numerical simulations show mean-field instabilities corresponding to stick-slip events, leading to premature switching. The model is relevant for the dynamics of driven vortex arrays in superconductors and other extended disordered systems.
A preprint by C. Reichhardt (UC-Davis) et al. reports numerical simulations of the motion of vortex lattices that are interacting with periodic pinning arrays and are driven by both ac and dc currents. The vortex flow was found to occur by the motion of interstitial vortices through the periodic potential generated by the vortices that remain pinned at the pinning sites. Shapiro steps were observed, and the widths of the phase-locked current steps as a function of the ac drive were found to follow a Bessel function, in agreement with theory.
The temperature and field dependence of the effective penetration depth lambda_[eff] in the vortex state of a d-wave superconductor, as measured by muon-spin-rotation (muSR) experiments, has been calculated by M.H.S. Amin (Simon Fraser) et al. using a nonlocal London model. The authors show that at temperatures below T* proportional to sqrt[B], the linear T dependence of lambda_[eff]^^[-2] crosses over to a T^3 dependence. This could provide an explanation for the low-temperature flattening of the lambda_[eff]^[-2] curve observed in a recent muSR experiment by J. E. Sonier et al. [Phys. Rev. Lett. 83, 4156 (1999)].
Using a d-wave gap model, E. Schachinger (Graz) and J. P. Carbotte (McMaster) have shown that the vortex-state thermal and transport properties of the high-Tc copper oxides are dominated by the extended quasiparticle states that exist along the nodal directions in momentum space. The authors find that the Doppler shift on these states due to the supercurrents circulating around the vortex cores introduces new Van Hove ridges into the energy-dependent local density of states as a function of distance in the regions between cores. The authors also examined the effect of impurities upon the topology of the Van Hove ridges in both the Born and unitary-scattering limits.
Using the Ginzburg-Landau equations, S. V. Yampolskii and F. M. Peeters (Antwerpen) have investigated the vortex state in thin (d << xi, lambda) and small (R ~ xi) mesoscopic disks in fields above H_[c2] where surface superconductivity occurs. The authors found both multivortex states and the giant vortex state.
Thin stacks consisting of a single intrinsic Josephson junction on (Bi,Pb)2Sr2Ca2Cu3O10+d [(Bi,Pb)-2223] thin films under the influence of external microwave fields have been investigated by Ch. Helm (Los Alamos and Regensburg) et al. The I-V characteristics showed a single resistive branch, a clear superconducting gap edge structure, and a pronounced current step in external microwave fields. Using numerical simulations including an ac magnetic field parallel to the layers, the authors found that the experimental features of the structure can be explained by a collective motion of Josephson vortices.
The microwave response of the organic superconductor kappa-(BEDT- TTF)2Cu(NCS)2 has been studied by M. M. Mola (Montana State) et al. using a cavity perturbation technique. The authors observed a Josephson plasma resonance below Tc (~10 K) and thus were able to investigate the vortex structure in the mixed state of this highly anisotropic type-II superconductor. In frequency studies over the range 28-153 GHz, the authors found that the weak-pinning theory of L. N. Bulaevskii et al. [Phys. Rev. Lett. 74, 801 (1995)] most consistently describes their results.
Theory
A preprint by D. Tanaskovic et al. (Belgrade) presents a derivation of the Ginzburg-Landau equations from the microscopic theory for clean, layered superconductors with d_[x^2-y^2] pairing symmetry, including the effect of Pauli paramagnetism. The authors calculate the upper critical field H_[c2] parallel to the c axis, the reversible magnetization M in high magnetic fields, and the high-temperature spin susceptibility. The authors find good agreement with experiment.
The spectral signatures of dimensional crossover in the continuum theory of a quasi-one-dimensional superconductor have been examined in a paper by E. W. Carlson (UCLA) et al. The authors compare their results with a number of experiments in the high-temperature superconductors, which are regarded as electronically quasi-one-dimensional on a local scale.
A model of superconductivity in the layered high-temperature superconducting cuprates is proposed in a preprint by A. A. Abrikosov (Argonne). The model is based on extended saddle-point singularities in the electron spectrum, weak screening of the Coulomb interaction, and phonon-mediated interaction between electrons, plus a small short-range repulsion of spin-fluctuation origin. The author uses the model to explain (a) the large values of Tc, (b) the isotope effect with oxygen and copper, (c) the existence of two types of order parameter, (d) the inelastic neutron-scattering peak, and (e) the positive curvature of the upper critical field as a function of temperature.
In a recent paper, E. Schachinger (Graz) and J. P. Carbotte (McMaster) showed that there exists a signature of the 41 meV neutron spin resonance in the optical data of optimally doped YBa2Cu3O6.95 (YBCO) and that an absolute estimate of its coupling to the charge carriers can be made. In a new preprint, these authors extend their analysis to Tl2Ba2CuO6+d (Tl-2201) with a Tc = 90 K. The authors find the spin resonance to be much broader than in YBCO and Bi2Sr2CaCu2O8+d (Bi-2212), although no neutron data exist as yet. The authors give a detailed analysis of the superconductivity of Tl-2201, in which the interactions responsible for superconductivity are constructed solely from consideration of optical data.
A preprint by G. G. Sergeeva (Kharkov) presents a scenario for the superconducting transition in quasi-two-dimensional superconductors. In this picture, the interaction of fluctuating spin waves with holes in the CuO2 planes leads to the pairing of holes, generates superconducting regions at T_[c0], and produces a temperature dependence in the interlayer coupling strength t_c(T). When t_c(T) is small, the transition of the sample to a coherent superconducting state occurs at Tc < T_[c0].
A detailed tight-binding analysis of the electron band structure of the CuO2 plane of layered cuprates has been performed by T. Mishonov and E. Penev (Leuven) using a sigma-band Hamiltonian with four orbitals: Cu 3d_[x^2-y^2], Cu 4s, O 2p_x, and O 2p_y. The authors used their results to fit the Fermi surface of Nd2-xCexCuO4 and Bi1.73Pb0.42Sr1.94Ca1.3Cu1.92O8+d measured in angle-resolved photoemission (ARPES) and angle-resolved ultraviolet spectroscopy (ARUPS) experiments. The authors also applied a similar approach to the RuO2 plane of Sr2RuO4.
A theoretical extension of the Brinkman-Rice picture to explain the metal - Mott-insulator transition is described in two preprints by H.-T. Kim (ETRI). For strongly correlated metals, including the high- temperature superconductors, the effective mass of a quasiparticle is found to obey m*/m = 1/(1 - kappa^2rho^2), where kappa is the correlation strength of the on-site Coulomb repulsion U and rho is the band-filling factor. Comparison with experimental data suggests that kappa = 1. The author also asserts that the extended Brinkman-Rice picture is better able to explain the Mott transition than Hubbard models.
Using an extended Hubbard model, J.-X. Zhu (TCSUH) et al. have calculated both the local (i.e., single-site) and spatially averaged differential tunneling conductance in d-wave superconductors containing nonmagnetic impurities in the unitary limit. The authors find that a random distribution of unitary impurities of any concentration can at most give rise to a finite zero-bias conductance (with no peak there) in spatially averaged non-STM tunneling. On the other hand, local tunneling in the immediate vicinity of an isolated impurity shows a conductance peak at zero bias. The authors also propose a theoretical model that explains the spatial structure in the STM tunneling conductance above a single Zn impurity in Bi-2212 recently observed by S. H. Pan et al. [see Oct. 15, 1999, High-Tc Update].
A phase diagram of temperature vs exchange field has been obtained by J.-X. Zhu (TCSUH) et al. using a BCS model for d-wave superconductivity in CuO2 layers coupled to ferromagnetic RuO2 layers in RuSr2GdCu2O8 (Ru- 1212). The authors found that the Fulde-Ferrell-Larkin-Ovchinnikov state is very sensitive to the band-filling factor. For strong exchange field, the authors find that superconductivity can exist only in the interfaces between ferromagnetic domains. The authors calculate the magnetization curve and compare with experimental results. The authors also propose an experiment by scanning tunneling spectroscopy (STS) near a single unitary impurity to detect the strength of the exchange interaction.
A preprint by N. E. Mavromatos and S. Sarkar (King's College London) discusses nodal liquids in the context of extended t-J models. The authors use the spin-charge separation ansatz as applied to the nodes of a d-wave superconducting gap. The authors point out the possibility of the existence of certain points in the parameter space of the model characterized by dynamical supersymmetries between the spinon and holon degrees of freedom, which are quite different from the symmetries in conventional supersymmetric t-J models.
A comprehensive study of doped RVB (resonating valence bond) states has been performed by M. Havilio and A. Auerbach (Technion). The authors found a fundamental connection between superconductivity and quantum spin fluctuations in underdoped cuprates: Cooper pair hopping strongly reduces the local magnetization m_0. The authors stress that this effect pertains to recent muon-spin-rotation experiments in which m_0 varies weakly with hole doping in the poorly conducting regime but drops precipitously above the onset of superconductivity.
As reported in a preprint by Y. Yuzhelevski et al. (Ben Gurion University of the Negev), a new procedure for the analysis of random telegraph signals in the time domain has been developed and applied to the analysis of voltage fluctuations in the current-induced dissipative state in superconducting thin films. The procedure, based entirely on the difference in the statistical properties of discrete Marcovian telegraph fluctuations and Gaussian background noise, ascribes each point of the experimental time record to one of the telegraph states.
The development of a microscopic theory for the coupling of intrinsic Josephson oscillations and dispersive phonon branches in layered superconductors has been developed by Ch. Preis (Regensburg) et al. The effect of phonons on the electronic c-axis transport enters through an effective longitudinal dielectric function. This coupling provides an explanation of recently observed subgap resonances in the I-V curves of anisotropic cuprate superconductors forming a stack of short Josephson junctions.
The mutual inductance of an infinite superconducting slab in the Meissner state probed by either point-dipole or circular-current-loop applied magnetic fields has been examined by M. W. Coffey (Colorado). The author accounts for the effect of a distinct, constant permeability of the slab and obtains expressions for the full mutual inductance and various approximations. The author also presents closed-form representations for an inductance per length factor, which has proven useful in inductance data inversion in order to obtain an absolute measurement of the London penetration depth.
RBa2Cu3O7-d
The Wiedemann-Franz ratio compares the thermal and electrical conductivities in a metal. Y. Zhang (Princeton) et al. describe a new way to determine its value, based on the thermal Hall conductivity, and they apply this technique to copper and untwinned YBa2Cu3O7-d. In the latter, the authors uncover a T-linear dependence and a suppression of the Hall-channel Wiedemann-Franz ratio.
In a preprint by S. W. Lovesey (Rutherford Appleton Laboratory) and U. Staub (PSI Villigen), the authors argue that the linewidth of the spectrum of neutrons scattered by Tb^[3+] in YBa2Cu3O7-d is created by the modulation of the crystal-field potential by lattice vibrations. The expression for the linewidth (also called the relaxation rate) contains an intermediate crystal-field state. The authors' model contains three states, the two probed in the scattering experiment and a third which is the agent for the principal relaxation mechanism. The authors also have used this model to successfully interpret inelastic neutron-scattering results for the relaxation of Ho^[3+] and Tm^[3+] in cuprates, adding support to the idea that the relaxation rate is dominated by the magneto-elastic interaction.
As reported by K. Grube (Karlsruhe) et al., the linear compressibilities and the thermal expansion of an untwinned nearly optimally doped YBa2Cu3O6.94 single crystal have been measured along the three crystallographic axes with a high-resolution dilatometer mounted in a high-pressure cell. The measurements were performed over a temperature range of 50-320 K under hydrostatic gas pressure up to 0.65 GPa. At 300 K, the measured bulk modulus is reduced and shows a strong enhancement under increasing pressure due to pressure-induced oxygen ordering. At lower temperatures, when oxygen ordering is frozen, the bulk modulus is increased and shows a significantly reduced enhancement under pressure. This pressure dependence, however, is still anomalously high, probably due to bonds of extremely different compressibilities within the unit cell. The wide spread of values of the bulk modulus reported in the literature can be explained by this strong pressure dependence.
The lattice parameters and Tc of Y1-yCayBa2Cu3O7-d under pressure up to 10 GPa have been determined by W. H. Fietz et al. (Karlsruhe) using a diamond anvil cell. By modifying the extended charge-transfer model to account for pressure-induced changes of the compressibilities, the authors found that the calculated Tc(P) values were in excellent agreement with the experimentally determined values.
A preprint by C.-J. Kim (KAERI) et al. reports that the growth mode of YBa2Cu3O7-d (YBCO) grains at the top surface of top-seeded melt-growth- processed YBCO superconductors depends strongly upon the thickness of the Sm1.8Ba2.4Cu3.4O7-d (SBCO) seeds. Thin slab-like SBCO seeds led to the nucleation of undesirable subsidiary YBCO grains in the seeded area, while such subsidiary nucleation was hardly observed when thick seeds were used. A related paper by C.-J. Kim (KAERI) et al. reports on the properties of YBCO superconductors fabricated using several SBCO seeds on the top surface to shorten the processing time. However, the authors found that the levitation force and trapped magnetic fields of the samples decreased as the number of seeds increased.
The effects of chemical doping and hydrostatic pressure on Tc of YBa2Cu3Ox (Y-123), Y0.89Ca0.11Ba2Cu3Ox [(Y,Ca)-123], and NdBa2Cu3Ox (Nd- 123) single crystals with various oxygen contents x have been studied by S. I. Schlachter et al. (Karlsruhe). In the underdoped region, all these compounds showed a peak in dTc/dP at the same n_h ~~ 0.11. The authors suggest that the origin of this peak is a strong influence of lattice deformations on the electronic structure.
Other Cuprates
The oxygen isotope effect on the relaxation rate of crystal-field excitations in the slightly underdoped high-temperature superconductor HoBa2Cu4O8 has been investigated by D. Rubio Temprano (ETH Zurich and PSI Villigen) et al. using inelastic neutron scattering. For the [16]^O compound there is clear evidence for the opening of an electronic gap in the normal state at T* ~~ 170 K, far above Tc (79.0 K). Upon replacing [16]^O with [18]^O, the authors found that Tc decreased marginally to 78.5 K, while T* increased to about 220 K. The authors note that this huge isotope shift for T*, which is absent in NMR and NQR experiments, suggests that the mechanism leading to an isotope effect on the pseudogap has to involve a time scale in the range 10^[-13] s < tau << 10^[-8] s.
The energy spectrum of incommensurate spin fluctuations in superconducting La2-xSrxCuO4 has been studied by C.-H. Lee (Tohoku) et al. using inelastic neutron-scattering experiments. The authors observed an energy gap in the spin excitation spectrum in the superconducting state of optimally doped (x = 0.15) and slightly overdoped (x = 0.18) samples. An enhancement in chi"(omega) caused by the peak-broadening also was observed at ~6 meV, which remains at Tc. For an underdoped sample with x = 0.10 and a highly overdoped sample with x = 0.25, no clear gap was observed, even though those samples showed bulk superconductivity.
Magnetic neutron-scattering measurements of incommensurate magnetic order in a superconducting single crystal of La1.88Sr0.12CuO4 are reported by H. Kimura (Tohoku) et al. The authors find that the incommensurate wavevectors that describe the static magnetism do not lie along high-symmetry directions of the underlying CuO2 lattice. The positions of the elastic magnetic peaks are consistent with those found in excess-oxygen-doped La2CuO4+y. This behavior differs from the magnetic order found in the low-temperature-tetragonal La1.6- xNd0.4SrxCuO4 material, for which stripes of spin and charge have been observed. The authors stress that these observations have important implications for any stripe model proposed to describe the static magnetism in orthorhombic La2CuO4-based superconductors.
Measurements of the oxygen isotope effect on the in-plane penetration depth lambda_[ab](0) in underdoped La2-xSrxCuO4 single crystals are reported by J. Hofer (Zurich) et al. The oxygen isotope effect on lambda_[ab]^[-2](0) was found to be -10(2)% for x = 0.080 and -8(1)% for x = 0.086, arising mainly from the oxygen mass dependence of the in- plane effective mass m_[ab]. The results suggest that lattice vibrations are important for the occurrence of high-temperature superconductivity.
Measurements of the temperature dependence of the penetration depth lambda_[ab] in several single crystals of La2-xSrxCuO4, Bi2Sr2CaCu2O8+d, and YBa2Cu3O7-d at various doping levels ranging from the under- to overdoped regimes have been carried out by J. Le Cochec (ESPCI Paris) et al. using a single-coil technique with a 10 pm resolution. The authors found that lambda_[ab] varies linearly with T in all samples, with a rapidly increasing slope dlambda_[ab]/dT as the doping decreases. The authors' analysis of the data indicates that a superconducting gap with d-wave symmetry is sufficient to account quantitatively for the above slope values in the optimally or overdoped samples. In the underdoped samples, while the d-wave model predicts much smaller values of the slope than those observed experimentally, the data are compatible with a model of thermodynamic phase fluctuations of the order parameter.
The ab-plane optical spectra of one underdoped and one nearly optimally doped single crystal of HgBa2Ca2Cu3O8+d (Hg-1223, Tc ~~ 135 K) in the frequency range 40-40,000 cm^[-1] have been investigated by J. J. McGuire (McMaster) et al. The authors obtained the frequency-dependent scattering rate by a Kramers-Kronig analysis of the reflectance. Both crystals were found to have a scattering-rate gap of about 1000 cm^[-1], which is much larger than the 700 cm^[-1] gap seen in optical studies of several cuprates with maximum Tc around 93 K. The authors suggest that there is a universal scaling between the scattering-rate gap and the maximum Tc for the cuprate superconductors.
Coated Conductors
As emphasized in a preprint by M. P. Chudzik (Northwestern and Argonne) et al., the next-generation wire technology based on high-temperature superconductors requires a biaxially textured template layer on which the superconductor will be coated. These template layers will need to be lattice-matched, chemically compatible, and economically feasible for lengths up to 1 km. A major hurdle to date in bringing these wires to market has been the slow deposition rate and/or complex deposition geometry needed to deposit the template layers. In this preprint, the authors describe experiments in which biaxially textured MgO template layers were deposited on continuously moving Hastelloy-C tapes to a length of 0.5 m by using a collimated-flux inclined-substrate-deposition (CF-ISD) system. The feed rate of the tapes was 6.1 cm/min over a total deposition zone of 10 cm, yielding a deposition rate for continuous coating of 0.6 micrometers/min and an MgO thickness of 1.0 micrometer in a single pass. MgO films grown to a thickness of 2.0 micrometers have yielded in-plane textures of 10-12 degrees full width at half maximum (FWHM).
Films
A weak spontaneous magnetic field appearing at the transition temperature of YBa2Cu3O7-d into the superconducting state has been observed by R. Carmi et al. (Technion). The effect was observed in 14 out of 15 epitaxial films grown on different substrates by two different techniques. The effect indicates a breaking of both parity and time- reversal symmetries in the superconductor. The authors offer two possible interpretations: (a) the condensate carries an intrinsic magnetic moment and (b) pi junctions may exist near the edges, producing circulating supercurrents and magnetic flux.
The anomalous decrease in microwave surface resistance R_s of superconducting YBa2Cu3O7-d films in the presence of a low dc magnetic field has been studied by X. S. Rao et al. (Singapore) using a microstrip resonator technique. From studies of the hysteresis in a dc magnetic field applied perpendicular to the film, the authors conclude that the decrease of R_s at low dc magnetic field is not due to vortices.
Magneto-optical imaging has been used by J. Albrecht et al. (MPI- Stuttgart) to investigate low-angle grain boundaries in YBa2Cu3O7-d thin films at 5 K. By a numerical analysis of the experimental data, the authors were able to determine the local current distribution in the grain boundary with a spatial resolution of a few micrometers. The authors found that the current density across the grain boundary depends strongly upon the local flux density.
The temperature dependence of the surface resistance and surface reactance of c-axis-oriented epitaxial thin films of GdBa2Cu3O7-d on (100)-cut LaAlO3 single-crystal substrates have been measured at 10.4, 14.7, and 17.9 GHz down to 1.4 K by L. V. Mercaldo et al. (Maryland) using the parallel-plate-resonator technique. Both the resistance and the reactance data show an unusual upturn at low temperature, and the resistance shows a strong peak around T_N (~~2.2 K) mainly due to the change in magnetic permeability.
A preprint by G. I. Harus (Ekaterinburg) et al. presents a systematic study of the resistivity and Hall effect in single-crystal Nd2-xCexCuO4- d films (0.12 <= x <= 0.20), with special emphasis on the temperature dependence of the normal-state conductance. The authors found two- dimensional weak localization effects in a normal-conducting underdoped sample (x = 0.12), an optimally doped sample (x = 0.15), and an overdoped sample (x = 0.18) in high magnetic fields B > B_[c2].
The properties of Ca-doped Bi2Sr2CuO6 (Bi-2201) films deposited at low temperatures on heated MgO (100) substrates by ion-beam sputtering (IBS) are discussed in a preprint by J. Yamada et al. (Mie). The authors found that plasma cleaning of the substrate surface results in significant improvements in Bi incorporation and crystallinity, evidently due to early-stage nucleation.
Other Activities
The effect of the magnetic-field inhomogeneity on vibrating-sample- magnetometer (VSM) measurements of the irreversibility field of superconductors has been analyzed by I. J. Daniel and D. P. Hampshire (Durham). In a large field gradient, the hysteresis in the magnetization signal at the drive frequency of the VSM can drop to zero more than 3 T below the true irreversibility field B_[irr]. The authors also discuss implications for SQUID measurements.
Overviews
The potential and applications of high-pressure techniques in synthesizing multilayered copper oxides and related structures are discussed in a review by H. Yamauchi (Tokyo Tech) and M. Karppinen (Tokyo Tech and Helsinki University of Technology). The authors emphasize the important historical discoveries of novel phases and discuss the present status of controlled production of high-quality samples of such phases (236 refs.).
As emphasized in a review by S. M. Anlage et al. (Maryland), near-field microwave microscopy has created the opportunity for a new class of electrodynamics experiments on materials. Freed from the constraints of traditional microwave optics, experiments can be carried out at high spatial resolution (to 1 micrometer) over a broad frequency range (100 GHz bandwidth). In addition, the measurements can be done quantitatively, so that images of microwave materials properties can be created. The authors review the five major types of near-field microwave microscopes, discuss their own form of microscopy in detail, and present quantitative images of microwave sheet resistance, dielectric constant, and dielectric tunability. The authors also discuss future prospects for near-field measurements of microwave electrodynamic properties (76 refs.).
Contributed by John R. Clem
Contents: Technology News is on page 7; Preprints begin on page 7; Coming Events begin on page 12; and Resources are on page 13.
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TECHNOLOGY NEWS (Also see Applications section of Nota Bene.)
This section describes progress in manufacturing, product development, and technology transfer in the high-Tc superconductivity field. Please send your contributions (product development information, news regarding technology transfer efforts, or any information you would like to share about your corporation or laboratory) to the editor.
In a recent announcement, Conductus, Inc. noted that the first urban TDMA field trials of its ClearSite[R] system expanded busy-hour capacity by 80% at a major cellular carrier's site in a highly populated urban area. This improvement represents a potential revenue increase of $300,000 per year, resulting in a payback of the carrier's investment in its ClearSite[R] system within approximately two months. ClearSite[R] superconducting wireless systems can expand coverage, reduce interference, and increase capacity for analog (1G), digital (2G), and next generation high-bandwidth digital (2.5G and 3G) wireless networks. In previous field trials ClearSite[R] systems have increased cell site minutes of use and thus revenues by 30% to more than 50% in coverage applications for 1G and 2G networks. Second-generation (2G) wireless offers increased performance and capacity over 1G networks and are widely available throughout the world from both cellular and PCS carriers. Next generation (2.5G and 3G) wireless networks will offer high-bandwidth digital service with initial 3G rollouts expected in 2001. Third-generation wireless is aimed at providing high-bandwidth digital services with speeds of 384 kbps to 2 Mbps that will support not only voice communications but also high-speed data, Internet access, and compressed video. For information, contact Conductus, Inc., 969 W. Maude Avenue, Sunnyvale, CA 94086; telephone (408) 523-9950; telefax (408) 523-9999.
Contributed by Sreeparna Mitra
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A. A. Abrikosov, "Theory of High-Tc Superconducting Cuprates Based on Experimental Evidence." Materials Science Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439; e-mail abrikosov@anl.gov preprint also available at http://xxx.lanl.gov/abs/cond-mat/9912394. 74.20.Fg; 74.25.Kc; 74.62.Dh; 74.72.Bk.
J. Albrecht, R. Warthmann, S. Leonhardt, and H. Kronmueller, "Current Densities in Low-Angle Grain Boundaries in YBCO." Submitted to the Proc. of the 6th Int. Conf. on Mater. and Mech. of Supercond. and High Temp. Supercond. (M^2S-HTSC-VI), Houston, Tex., Feb. 20-25, 2000; to be published in Physica C. Max-Planck-Institut fuer Metallforschung, D- 70569 Stuettgart, GERMANY; telephone +49 711 6891 806; e-mail jalbrecht@vaxph.mpi-stuttgart.mpg.de.
M.H.S. Amin, M. Franz, and Ian Affleck, "On the Effective 'Penetration Depth' in the Vortex State of a d-Wave Superconductor." Department of Physics, Simon Fraser University, Burnaby, British Columbia, CANADA V5A 1S6; e-mail msamin@sfu.ca preprint also available at http://xxx.lanl.gov/abs/cond-mat/9912196.
Steven M. Anlage, D. E. Steinhauer, B. J. Feenstra, C. P. Vlahacos, and F. C. Wellstood, "Near-Field Microwave Microscopy of Materials Properties." Presented at the NATO Adv. Study Inst. (ASI) on Microwave Supercond., Millau, France, Aug. 29-Sept. 10, 1999; to be published in Microwave Supercond., edited by H. Weinstock and M. Nisenoff (Kluwer, Amsterdam, 2000). Center for Superconductivity Research, Department of Physics, University of Maryland, College Park, MD 20742-4111; telephone (301) 405-7321; telefax (301) 405-3779; e-mail anlage@squid.umd.edu preprint also available at http://xxx.lanl.gov/abs/cond-mat/0001075.
E. W. Carlson, D. Orgad, S. A. Kivelson, and V. J. Emery, "Dimensional Crossover in Quasi One-Dimensional and High-Tc Superconductors." Department of Physics, University of California, Los Angeles, CA 90095; D. Orgad's e-mail dror@physics.ucla.edu preprint also available at http://xxx.lanl.gov/abs/cond-mat/0001058.
R. Carmi, E. Polturak, G. Koren, and A. Auerbach, "Appearance of Spontaneous Macroscopic Magnetization at the Superconducting Transition of YBa2Cu3O7-d." Contact E. Polturak, Department of Physics, Technion - Israel Institute of Technology, Haifa 32000, ISRAEL; telephone +972 4 8292761; telefax +972 4 8221514; e-mail emilp@physics.technion.ac.il preprint also available at http://xxx.lanl.gov/abs/cond-mat/0001050. 74.25.-q; 74.20.-z; 74.20.Mn
M. P. Chudzik, R. A. Erck, U. Balachandran, Z. P. Luo, D. J. Miller, and C. R. Kannewurf, "High-Rate Reel-to-Reel Continuous Coating of Biaxially Textured Magnesium Oxide Thin Films for Coated Conductors." To be presented at the 6th Int. Conf. on Mater. and Mech. of Supercond. and High Temp. Supercond. (M^2S-HTSC-VI), Houston, Tex., Feb. 20-25, 2000. Contact Janice Coble, Materials Science Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439; telephone (630) 252-5497; telefax (630) 252-9595; e-mail coble@anl.gov.
Mark W. Coffey, "On Mutual Inductance Measurements for Determining the London Penetration Depth." To be published in J. Appl. Phys. Department of Physics, University of Colorado, Boulder, CO 80309; e-mail mcoffey@stripe.colorado.edu. Key words: mutual inductance, magnetic flux, London penetration depth, inversion, thin-film superconductor, magnetic permeability, Meissner state. 74.20.De; 74.25.Ha; 74.76.-w; 74.80.Dm.
G. W. Crabtree, W. K. Kwok, L. M. Paulius, A. M. Petrean, R. J. Olsson, G. Karapetrov, V. Tobos, and W. G. Moulton, "The Effect of Disorder on the Critical Points in the Vortex Phase Diagram of YBCO." Submitted to Physica C: Proc. of the First Euroconf. on Vortex Matter in Superconductors (VORTEX99), Crete, Greece, Sept. 18-24, 1999. Contact Janice Coble, Materials Science Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439; telephone (630) 252-5497; telefax (630) 252-9595; e-mail coble@anl.gov.
Ian J. Daniel and Damian P. Hampshire, "Harmonic Calculations and Measurements of the Irreversibility Field Using a Vibrating Sample Magnetometer." To be published in Phys. Rev. B. Superconductivity Group, Department of Physics, University of Durham, South Road, Durham DH1 3LE, UNITED KINGDOM; telephone +44 191 374 2167; telefax +44 191 374 3749. 74.25.Ha; 74.60.Ec; 74.60.Ge; 74.60.Jg.
A. Deptula, W. Lada, T. Olczak, J. E. Ostenson, T. A. Cruse, and K. C. Goretta, "Sol-Gel Process for Synthesis of NdBa2Cu3Ox Powders from Acidic Metal Acetates." Submitted to Supercond. Sci. & Technol. Contact Janice Coble, Materials Science Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439; telephone (630) 252-5497; telefax (630) 252-9595; e-mail coble@anl.gov.
Walter H. Fietz, Frank W. Hornung, Kai Grube, Sonja I. Schlachter, Thomas Wolf, Bernhard Obst, and Peter Schweiss, "Structure and Tc of Y0.8Ca0.2Ba2Cu3O6.92 Under High Pressure." Report #FZK-ITP-GSL-1999-02; to be published in J. Low Temp. Phys. Forschungszentrum Karlsruhe, Institut fuer Technische Physik, Postfach 3640, D-76021 Karlsruhe, GERMANY; e-mail walter.fietz@itp.fzk.de preprint also available at http://xxx.lanl.gov/abs/cond-mat/9912356. 74.25.Ld; 74.62.-c; 74.62.Fj; 74.72.Bk.
K. Grube, H. Leibrock, W. H. Feitz, S. I. Schlachter, A. I. Rykov, S. Tajima, P. Schweiss, B. Obst, and H. Wuehl, "Compressibility and Thermal Expansion of YBa2Cu3Ox." Report #FZK-ITP-GSL-1999-04; to be published in J. Low. Temp. Phys. Forschungszentrum Karlsruhe, Institut fuer Technische Physik, Postfach 3640, D-76021 Karlsruhe, GERMANY; W. H. Feitz's e-mail walter.fietz@itp.fzk.de preprint also available at http://xxx.lanl.gov/abs/cond-mat/9912359. 62.20.Dc; 64.70.Pf; 74.72.Bk.
G. I. Harus, A. N. Ignatenkov, A. I. Ponomarev, L. D. Sabirzyanova, N. G. Shelushinina, and A. A. Ivanov, "Two-Dimensional Weak Localization Effects in High Temperature Superconductor Nd2-xCexCuO4-d." Report # IMP-04-21-99; to be published in JETP. Institute of Metal Physics, Kovalevskaya str. 18, Ekaterinburg 620219, RUSSIA; A. N. Ignatenkov's e- mail ignat@imp.uran.ru preprint also available at http://xxx.lanl.gov/abs/cond-mat/9912004. 74.60.Ec; 74.76.Bz.
Moshe Havilio and Assa Auerbach, "Correlations in Doped Antiferromagnets." Department of Physics, Technion - Israel Institute of Technology, Haifa 32000, ISRAEL; e-mail havilio@pharaoh.technion.ac.il preprint also available at http://xxx.lanl.gov/abs/cond-mat/0001007.
Ch. Helm, A. Odagawa, M. Sakai, H. Adachi, K. Setsune, and R. Kleiner, "Interpretation of a Microwave Induced Current Step in a Single Intrinsic Josephson Junction on a Bi-2223 Thin Film." To be presented at the 6th Int. Conf. on Mater. and Mech. of Supercond. and High Temp. Supercond. (M^2S-HTSC-VI), Houston, Tex., Feb. 20-25, 2000; to be published in Physica C. Institute of Theoretical Physics, University of Regensburg, D-93040 Regensburg, GERMANY; e-mail christian.helm@physik.uni-regensburg.de preprint also available at http://xxx.lanl.gov/abs/cond-mat/0001152.
J. Hofer, K. Conder, T. Sasagawa, Guo-meng Zhao, M. Willemin, H. Keller, and K. Kishio, "Oxygen Isotope Effect on the In-Plane Penetration Depth in Underdoped La2-xSrxCuO Single Crystals." Submitted to Phys. Rev. Lett. Physik-Institut der Universitaet Zurich, Winterthurerstrasse 190, CH-8057 Zurich, SWITZERLAND; telephone +41 1 635 5774; telefax +41 1 635 5704; e-mail jhofer@physik.unizh.ch preprint also available at http://xxx.lanl.gov/abs/cond-mat/9912493. 74.25.Ha; 74.20.Mn; 82.20.Tr.
Chan-Joong Kim, Young A. Jee, Gye-Won Hong, Tae-Hyun Sung, Young-Hee Han, Sang-Chul Han, Sang-Joon Kim, W. Bieger, and G. Fuchs, "Effects of the Seed Dimension on the Top Surface Growth Mode and the Magnetic Properties of Top-Seeded Melt Growth Processed YBCO Superconductors." To be published in Physica C. Superconductivity Research Laboratory, Korea Atomic Energy Research Institute, P.O. Box 105, Yusung, Taejon 305-600, SOUTH KOREA; telephone +82 42 868 8908; telefax +82 42 862 5496; e-mail cjkim2@nanum.kaeri.re.kr.
Chan-Joong Kim, Young A. Jee, Ho-Jin Kim, Jin-Ho Joo, Sang-Chul Han, Han-Young-Hee Han, Tae-Hyun Sung, Sang-Jun Kim, and Gye-Won Hong, "Multi-Seeding of YBCO Superconductors." To be published in Advances in Supercond. XII: Proc. of the 12th Int. Symp. on Superconductivity (ISS'99), Morioka, Japan, Oct. 17-19, 1999. Superconductivity Research Laboratory, Korea Atomic Energy Research Institute, P.O. Box 105, Yusung, Taejon 305-600, SOUTH KOREA; telephone +82 42 868 8908; telefax +82 42 862 5496; e-mail cjkim2@nanum.kaeri.re.kr.
Hyun-Tak Kim, "Extension of the Brinkman-Rice Picture and the Mott Transition." Submitted to the Proc. of the 6th Int. Conf. on Mater. and Mech. of Supercond. and High Temp. Supercond. (M^2S-HTSC-VI), Houston, Tex., Feb. 20-25, 2000; to be published in Physica C. Telecom. Basic Research Laboratory, Electron Telecommunication Research Institute (ETRI), Taejon 305-350, KOREA; telephone +82 42 860 5731; telefax +82 42 860 6836; e-mail htkim@utopia.etri.re.kr or kimht45@hotmail.com preprint also available at http://xxx.lanl.gov/abs/cond-mat/0001008. 71.27.+a; 71.30.+h; 74.20.Mn; 74.20.Fg.
Hyun-Tak Kim, "Extension of the Brinkman-Rice Picture and Its Application to the Heat Capacity Data of Sr1-xLaxTiO3, La2-xSrxCuO4 and YBa2Cu3O7-d." Telecom. Basic Research Laboratory, Electron Telecommunication Research Institute (ETRI), Taejon 305-350, KOREA; telephone +82 42 860 5731; telefax +82 42 860 6836; e-mail htkim@utopia.etri.re.kr or kimht45@hotmail.com. 71.27.+a; 71.30.+h; 74.20.Mn; 74.20.Fg.
H. Kimura, H. Matsushita, K. Hirota, Y. Endoh, K. Yamada, G. Shirane, Y. S. Lee, M. A. Kastner, and R. J. Birgeneau, "Incommensurate Geometry of the Elastic Magnetic Peaks in Superconducting La1.88Sr0.12CuO4." Research Institute for Scientific Measurements, Tohoku University, Katahira 2-1-1, Aoba-ku, Sendai 980-8577, JAPAN; e-mail kimurah@rism.tohoku.ac.jp preprint also available at http://xxx.lanl.gov/abs/cond-mat/9912401. 74.72.Dn; 75.10.Jm; 75.30.Fv; 75.50.Ee.
M. Konczykowski, C. J. van der Beek, S. Colson, M. V. Indenbom, P. H. Kes, Y. Platiel, and E. Zeldov, "Magnetization Decay Due to Vortex Phase Boundary Motion in BSCCO." Submitted to the Proc. of the 6th Int. Conf. on Mater. and Mech. of Supercond. and High Temp. Supercond. (M^2S-HTSC- VI), Houston, Tex., Feb. 20-25, 2000. Laboratoire des Solides Irradies, Ecole Polytechnique, F-91128 Palaiseau, FRANCE; C. J. van der Beek's e- mail beek@hp1sesi.polytechnique.fr preprint also available at http://xxx.lanl.gov/abs/cond-mat/9912283.
M. Konczykowski, C. J. van der Beek, M. V. Indenbom, and E. Zeldov, "Melting of Regular and Decoupled Vortex Lattices in BSCCO Crystals." Submitted to the Proc. of the 6th Int. Conf. on Mater. and Mech. of Supercond. and High Temp. Supercond. (M^2S-HTSC-VI), Houston, Tex., Feb. 20-25, 2000. Laboratoire des Solides Irradies, Ecole Polytechnique, F- 91128 Palaiseau, FRANCE; C. J. van der Beek's e-mail beek@hp1sesi.polytechnique.fr preprint also available at http://xxx.lanl.gov/abs/cond-mat/9912284.
W. K. Kwok, R. J. Olsson, G. Karapetrov, Lisa M. Paulis, W. G. Moulton, David J. Hofman, and George W. Crabtree, "The Effect of Disorder on the Critical Points in the Vortex Phase Diagram of YBCO." Submitted to the Proc. of the 6th Int. Conf. on Mater. and Mech. of Supercond. and High Temp. Supercond. (M^2S-HTSC-VI), Houston, Tex., Feb. 20-25, 2000; to be published in Physica C. Contact Janice Coble, Materials Science Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439; telephone (630) 252-5497; telefax (630) 252-9595; e-mail coble@anl.gov.
J. Le Cochec, G. Lamura, A. Gauzzi, F. Licci, A. Revcolevschi, A. Erb, G. Deutscher, and J. Bok, "Effect of Doping on the Linear Temperature Dependence of the Magnetic Penetration Depth in Cuprate Superconductors." Submitted to Physica C: Proc. of the 6th Int. Conf. on Mater. and Mech. of Supercond. and High Temp. Supercond. (M^2S-HTSC- VI), Houston, Tex., Feb. 20-25, 2000. Contact A. Gauzzi, MASPEC- Consiglio Nazionale delle Ricerche, Area delle Scienze, I-43010 Parma- Fontannini, ITALY; e-mail gauzzi@maspec.bo.cnr.it preprint also available at http://xxx.lanl.gov/abs/cond-mat/0001045.
Chul-Ho Lee, Kazuyoshi Yamada, Yasuo Endoh, Gen Shirane, R. J. Birgeneau, M. A. Kastner, M. Greven, and Y.-J. Kim, "Energy Spectrum of Spin Fluctuations in Superconducting La2-xSrxCuO4 (0.10 <= x <= 0.25)." Submitted to J. Phys. Soc. Jpn. Electrotechnical Laboratory, Umezono 1- 1-4, Tsukuba 305-8568, JAPAN; e-mail chlee@etl.go.jp preprint also available at http://xxx.lanl.gov/abs/cond-mat/9912453. Key words: La2- xSrxCuO4, high-Tc superconductor, spin fluctuation, neutron scattering.
Stephen W. Lovesey and Urs Staub, "A Magneto-Elastic Model for the Relaxation of Lanthanide Ions in YBa2Cu3O7-d Observed by Neutron Scattering." ISIS Facility, Rutherford Appleton Laboratory, Oxfordshire OX11 0QX, UNITED KINGDOM; e-mail s.w.lovesey@rl.ac.uk Urs Staub's e- mail at Paul Scherrer Institute urs.staub@psi.ch. 74.72.Bk; 76.20.+q; 71.70.Ch; 25.40.Fq.
M. Cristina Marchetti, A. Alan Middleton, and Thomas Prellberg, "Viscoelastic Depinning of Driven Systems: Mean-Field Plastic Scallops." Department of Physics, Syracuse University, Syracuse, NY 13244; A. Alan Middleton's e-mail aam@suhep.phy.syr.edu preprint also available at http://xxx.lanl.gov/abs/cond-mat/9912461. 62.20.Fe; 74.60.Ge.
Nick E. Mavromatos and Sarben Sarkar, "Nodal Liquids in Extended t-J Models and Dynamical Supersymmetry." Department of Physics, King's College London Strand, London WC2R 2LS, UNITED KINGDOM; e-mail nikolaos.mavromatos@cern.ch preprint also available at http://xxx.lanl.gov/abs/cond-mat/9912323.
J. J. McGuire, M. Windt, T. Startseva, T. Timusk, D. Colson, and V. Viallet-Guillen, "Scattering Rate Gap in the IR Response of HgBa2Ca2Cu3O8+d." Submitted to Phys. Rev. Lett. Department of Physics and Astronomy, McMaster University, Hamilton, Ontario, CANADA L8S 4M1; e-mail mcguirjj@mcmail.cis.mcmaster.ca preprint also available at http://xxx.lanl.gov/abs/cond-mat/9912338. 74.25.Gz; 74.72.Gr; 78.20.Ci.
Lucia V. Mercaldo, Vladimir V. Talanov, and Steven M. Anlage, "Microwave Electrodynamics of the Antiferromagnetic Superconductor GdBa2Cu3O7-d." Submitted to the Proc. of the 6th Int. Conf. on Mater. and Mech. of Supercond. and High Temp. Supercond. (M^2S-HTSC-VI), Houston, Tex., Feb. 20-25, 2000. Center for Superconductivity Research, Department of Physics, University of Maryland, College Park, MD 20742-4111; e-mail luciam@squid.umd.edu preprint also available at http://xxx.lanl.gov/abs/cond-mat/9912418.
T. Mishonov and E. Penev, "Tight-Binding Modeling of the Electronic Band Structure of Layered Superconducting Perovskites." To be published in J. Phys.: Cond. Matter. Laboratorium voor Vaste-Stoffysica en Magnetisme, Katholieke Universiteit Leuven, Celestijnenlaan 200 D, B- 3001 Leuven, BELGIUM; E. Penev's e-mail at Fritz-Haber-Institut der Max- Planck-Gessellschaft evgeni@theo24.rz-berlin.mpg.de preprint also available at http://xxx.lanl.gov/abs/cond-mat/0001049. 74.25.Jb; 71.25.Pi; 74.72.-h.
M. M. Mola, S. Hill, J. T. King, C. P. McRaven, J. S. Qualls, and J. S. Brooks, "Determination of the Vortex Structure in kappa-(BEDT- TTF)2Cu(NCS)2 by Josephson Plasma Resonance." Department of Physics, Montana State University, Bozeman, MT 59717; S. Hill's e-mail hill@physics.montana.edu preprint also available at http://xxx.lanl.gov/abs/cond-mat/0001149. 71.18.+y; 71.27.+a; 74.25.Nf.
N. M. Murphy, S. E. Dorris, D. J. Miller, Z. P. Luo, H. Claus, and V. A. Maroni, "Phase Formation and Superconductivity in PIT-Type (Bi,Pb)- 1212." To be presented at the 6th Int. Conf. on Mater. and Mech. of Supercond. and High Temp. Supercond. (M^2S-HTSC-VI), Houston, Tex., Feb. 20-25, 2000. Contact Janice Coble, Materials Science Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439; telephone (630) 252-5497; telefax (630) 252-9595; e-mail coble@anl.gov.
C. J. Olson and C. Reichhardt, "Transverse Depinning in Strongly Driven Vortex Lattices with Disorder." To be published in Phys. Rev. B. Department of Physics, University of California at Davis, Davis, CA 95616; e-mail olson@moran.ucdavis.edu preprint also available at http://xxx.lanl.gov/abs/cond-mat/9910017. 74.60.Ge.
Ch. Preis, Ch. Helm, K. Schmalzl, Ch. Walter, and J. Keller, "Microscopic Theory of the Coupling of Intrinsic Josephson Oscillations and Phonons." Submitted to the Proc. of the 6th Int. Conf. on Mater. and Mech. of Supercond. and High Temp. Supercond. (M^2S-HTSC-VI), Houston, Tex., Feb. 20-25, 2000; to be published in Physica C. Institute of Theoretical Physics, University of Regensburg, D-93040 Regensburg, GERMANY; Ch. Helm's e-mail hec03780@rphs1.physik.uni- regensburg.de; preprint also available at http://xxx.lanl.gov/abs/cond- mat/0001150.
X. S. Rao, C. K. Ong, B. B. Jin, and Y. P. Feng, "Hysteresis Measurement of Anomalous Microwave Surface Resistance in Superconducting Thin Films." Submitted to the Proc. of the 6th Int. Conf. on Mater. and Mech. of Supercond. and High Temp. Supercond. (M^2S-HTSC-VI), Houston, Tex., Feb. 20-25, 2000; to be published in Physica C. Center for Superconducting and Magnetic Materials and Department of Physics, National University of Singapore, Singapore 119260, SINGAPORE; e-mail scip7099@leonis.nus.edu.sg preprint also available at http://xxx.lanl.gov/abs/cond-mat/0001016.
Charles Reichhardt, Richard T. Scalettar, Gergely T. Zimanyi, and Niels Gronbech-Jensen, "Phase-Locking of Vortex Lattices Interacting with Periodic Pinning." Department of Physics, University of California at Davis, Davis, CA 95616; e-mail charlesr@moran.ucdavis.edu preprint also available at http://xxx.lanl.gov/abs/cond-mat/9912381. 74.60.Ge; 74.60.Jg.
Charles Reichhardt, Anne van Otterlo, and Gergely T. Zimanyi, "Vortices Freeze Like Window Glass: The Vortex Molasses Scenario." To be published in Phys. Rev. Lett. Department of Physics, University of California at Davis, Davis, CA 95616; e-mail charlesr@moran.ucdavis.edu preprint also available at http://xxx.lanl.gov/abs/cond-mat/9910314. 74.60.Ge; 74.25.Dw.
E. Schachinger and J. P. Carbotte, "Coupling to Spin Excitations Revealed in Optical Data." To be presented at the 6th Int. Conf. on Mater. and Mech. of Supercond. and High Temp. Supercond. (M^2S-HTSC-VI), Houston, Tex., Feb. 20-25, 2000. Institut fuer Theoretische Physik, Technische Universitaet Graz, A-8010 Graz, AUSTRIA; e-mail schachinger@itp.tu-graz.ac.at.
E. Schachinger and J. P. Carbotte, "Doppler Shift on Local Density of States and Local Impurity Scattering in the Vortex State." Submitted to Phys. Rev. B. Institut fuer Theoretische Physik, Technische Universitaet Graz, A-8010 Graz, AUSTRIA; e-mail schachinger@itp.tu- graz.ac.at; preprint also available at http://xxx.lanl.gov/abs/cond- mat/0001029. 74.20.Fg; 74.25.Ha; 74.72.-h.
S. I. Schlachter, K.-P. Weiss, W. H. Fietz, K. Grube, H. Leibrock, Th. Wolf, B. Obst, P. Schweiss, M. Klaeser, and H. Wuhl, "The Effects of Chemical Doping and Hydrostatic Pressure on Tc of Y1-yCayBa2Cu3Ox and NdBa2Cu3Ox Single Crystals." Report #FZK-ITP-GSL-1999-03; to be published in J. Low. Temp. Phys. Forschungszentrum Karlsruhe, Institut fuer Technische Physik, D-76021 Karlsruhe, GERMANY; W. H. Fietz's e-mail walter.fietz@itp.fzk.de preprint also available at http://xxx.lanl.gov/abs/cond-mat/9912357. 74.62.-c; 74.62.Fj; 74.62.Dh; 74.72.-h; 74.72.Bk.
G. G. Sergeeva, "Scenario of Superconducting Transition for Quasi Two Dimension HSC." National Science Center, Kharkov Institute of Physics and Technology, Academicheskaya st. 1, 61108, Kharkov, UKRAINE; e-mail gsergeeva@kipt.kharkov.ua preprint also available at http://xxx.lanl.gov/abs/cond-mat/9912042.
D. Tanaskovic, Z. Radovic, and L. Dobrosavljevic-Grujic, "Spin Paramagnetism in d-Wave Superconductors." Submitted to Phys. Rev. B. Institute of Physics, P.O. Box 57, 11080 Belgrade, YUGOSLAVIA; e-mail tanasko@phy.bg.ac.yu preprint also available at http://xxx.lanl.gov/abs/cond-mat/9912140. 74.72.-h; 74.25.Ha.
D. Rubio Temprano, J. Mesot, S. Janssen, K. Conder, A. Furrer, H. Mutka, and K. A. Mueller, "Large Isotope Effect on the Pseudogap in the High- Temperature Superconductor HoBa2Cu4O8." To be published in Phys. Rev. Lett. Laboratory for Neutron Scattering, ETH Zurich and Paul Scherrer Institute, Building WHGA 131, CH-5232 Villigen PSI, SWITZERLAND; telephone +41 56 310 4686; telefax +41 56 310 2939; e-mail daniel.rubio@psi.ch.
U. Tutsch, P. Schweiss, R. Hauff, B. Obst, Th. Wolf, and H. Wuehl, "Calorimetric Investigation of NdBa2Cu3Ox Single Crystals." Report #FZK-ITP-GSL-1999-05; to be published in J. Low. Temp. Phys. Forschungszentrum Karlsruhe, Institut fuer Technische Physik, Postfach 3640, D-76021 Karlsruhe, GERMANY; preprint also available at http://xxx.lanl.gov/abs/cond-mat/9912361. 74.25.Bt; 74.62.-c; 74.72.-h.
C. J. van der Beek, S. Colson, M. V. Indenbom and M. Konczykowski, "Supercooling of the Disordered Vortex Lattice in Bi2Sr2CaCu2O8+d." Submitted to Phys. Rev. Lett. Laboratoire des Solides Irradies, Ecole Polytechnique, F-91128 Palaiseau, FRANCE; e-mail beek@hp1sesi.polytechnique.fr preprint also available at http://xxx.lanl.gov/abs/cond-mat/9912276.
C. J. van der Beek, S. Colson, M. Konczykowski, and M. V. Indenbom, "Supercooling of the High Field Vortex Phase in Single Crystalline BSCCO." Submitted to the Proc. of the 6th Int. Conf. on Mater. and Mech. of Supercond. and High Temp. Supercond. (M^2S-HTSC-VI), Houston, Tex., Feb. 20-25, 2000. Laboratoire des Solides Irradies, Ecole Polytechnique, F-91128 Palaiseau, FRANCE; e-mail beek@hp1sesi.polytechnique.fr preprint also available at http://xxx.lanl.gov/abs/cond-mat/9912280.
C. J. van der Beek, S. Colson, M. Konczykowski, M. V. Indenbom, R. J. Drost, and P. H. Kes, "Magnetic Relaxation in the 'Bragg-Glass' Phase in BSCCO." Submitted to the Proc. of the 6th Int. Conf. on Mater. and Mech. of Supercond. and High Temp. Supercond. (M^2S-HTSC-VI), Houston, Tex., Feb. 20-25, 2000. Laboratoire des Solides Irradies, Ecole Polytechnique, F-91128 Palaiseau, FRANCE; e-mail beek@hp1sesi.polytechnique.fr preprint also available at http://xxx.lanl.gov/abs/cond-mat/9912282.
Jiro Yamada, Masaki Tada, Akinori Hashizume, Ken-ichi Itoh, Vallabhapurapu, V. Srinivasu, Vallabhapurapu Sreedevi, and Tamio Endo, "Improvements of Bi-Incorporation and Crystal Growth by Plasma Cleaning in Bi2201 Thin Film Preparations." To be published in Trans. Mat. Res. Soc. Jpn. Faculty of Engineering, Mie University, Kamihama, Tsu, Mie 514-8507, JAPAN; Tamio Endo's telephone +81 592 32 1211; telefax +81 592 31 9471; e-mail endo@cm.elec.mie-u.ac.jp. Key words: Bi2201 thin film growth, ion-beam sputtering, plasma cleaning, composition, Bi incorporation.
Hisao Yamauchi and Maarit Karppinen, "Application of High-Pressure Techniques: Stabilization and Oxidation-State Control of Novel Superconductive and Related Multi-Layered Copper Oxides." To be published in Supercond. Sci. & Technol. Materials & Structures Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 227, JAPAN; telephone +81 45 924-5315; telefax +81 45 924-5365 or -5360; e-mail yamauchi@materia.titech.ac.jp.
S. V. Yampolskii and F. M. Peeters, "Vortex Structure of Thin Mesoscopic Disks with Enhanced Surface Superconductivity." Departement Natuurkunde, Universiteit Antwerpen (UIA), Universiteitsplein 1, B-2610 Antwerpen, BELGIUM; F. M. Peeter's e-mail peeters@uia.ua.ac.be. 74.20.De; 74.25.Dw; 74.60.Ec.
Y. Yuzhelevski, M. Yuzhelevski, and G. Jung, "Random Telegraph Noise Signal Analysis in Time Domain." To be published in Rev. Sci. Instrum. Department of Physics, Ben-Gurion University of the Negev, P.O. Box 653, 84105 Beer-Sheva, ISRAEL; G. Jung's telephone +972 7 646 1166; telefax +972 7 647 2903; e-mail jung@bgumail.bgu.ac.il. 05.40.Jc; 74.40.+k.
Y. Zhang, N. P. Ong, Z. A. Xu, K. Krishana, R. Gagnon, and L. Taillefer, "Determining the Wiedemann-Franz Ratio from the Thermal Hall Conductivity: Application to Cu and YBa2Cu3O6.95." Submitted to Phys. Rev. Lett. Joseph Henry Laboratories of Physics, Princeton University, Princeton, NJ 08544; e-mail zyx@princeton.edu preprint also available at http://xxx.lanl.gov/abs/cond-mat/0001037. 74.72.-h; 72.15.Eb; 72.15.Gd; 72.15.Lh.
Jian-Xin Zhu, C. S. Ting, and C. W. Chu, "Superconductivity in Ferromagnet RuSr2GdCu2O8." Department of Physics and Texas Center for Superconductivity, University of Houston, Houston, TX 77204-5932; telephone (713) 743-8276; telefax (713) 743-8201; e-mail jxzhu@mira.tcs.uh.edu preprint also available at http://xxx.lanl.gov/abs/cond-mat/0001024. 74.25.Ha; 75.30.Et.
Jian-Xin Zhu, C. S. Ting, and Chia-Ren Hu, "Roles Played by Unitary Impurities in Non-STM-Types of Tunneling in High-Tc Superconductors." Department of Physics and Texas Center for Superconductivity, University of Houston, Houston, TX 77204-5932; telephone (713) 743-8276; telefax (713) 743-8201; e-mail jxzhu@mira.tcs.uh.edu preprint also available at http://xxx.lanl.gov/abs/cond-mat/0001038. 74.50.+r; 74.62.Dh; 74.80.-g.
COMING EVENTS (An * indicates a previously listed event. Also see complete listing of upcoming conferences and workshops at our Web site http://www.iitap.iastate.edu/htcu/comevents.html.)
*March 4 - 7, 2000: International Workshop on Latest Developments in Low-Density and Low-Dimensional Electronic Systems, University of Florida, Department of Physics, Gainesville, Fla. Main theme of the workshop is the interplay between low dimensionality, low carrier density, and transport and magnetic properties of novel materials. Program is organized in ascending dimension and includes the following topics: (0-D and 1-D) quantum dots, quantum wires, and nanotubes; (2-D) stripes in high-Tc materials, quantum Hall effect, metal-insulator transition at B=0, and superconductor-insulator transition; (3-D) itinerant ferromagnetism in low-density materials, magnetic field induced transitions, spin- and charge-density waves, and Kondo insulators. Special focus will be on the use of high magnetic fields at the National High Magnetic Field Laboratory in studies of low-density and low-dimensional materials. Invited talks and poster sessions. Application deadline, February 1, 2000. For information, contact Alan Dorsey, 2116 New Physics Bldg., Department of Physics, University of Florida, P.O. Box 118440, Gainesville, FL 32611-8440; telephone (352) 392-4031; telefax (352) 392-0524; e-mail dorsey@phys.ufl.edu Web-site http://www.phys.ufl.edu/workshops/ld3.html.
*March 20 - 24, 2000: 2000 March Meeting, Minneapolis Convention Center, Minneapolis, Minn. Sessions on superconductivity will include the following topics: synthesis, growth, and processing (bulk and films); thermodynamic and transport properties; mechanical and structural properties; electronic structure and spectroscopic properties; flux pinning and flux dynamics; spin properties (NMR, NQR, etc.); tunnel junctions, devices, and Josephson arrays; quantum computing; and other focused sessions. For further general information, contact Donna Baudrau, Manager, APS Meetings Department, telephone (301) 209-3285, e-mail baudrau@aps.org more information on the March meeting is available at the Web site http://www.aps.org/meet/MAR00/.
June 11 - 15, 2000: Superconductors for Applications, Materials Properties and Devices (ICMC'2000), Hotel Sofitel Rio Palace, Copacabana Beach, Rio de Janeiro, Brazil. Topics include materials preparation techniques, material properties, application devices, cryogenic refrigerators, and complementary materials. No parallel sessions. Abstract deadline, February 29, 2000. Contact Roberto Nicolsky, Conference Chair, C.P. 68515, Rio de Janeiro 21945-970, Brazil; telephone +55 21 260 1092; e-mail icmc2000@lasup.dee.ufrj.br.
June 12 - 23, 2000: Workshop on Correlation Effects in Electronic Structure Calculations, Trieste, Italy. The first part of the workshop will provide a pedagogical and practical introduction to the main methods currently in use (LDA + U, DMFT, and GW) and complemented with practical demonstrations of computer codes. Second part will focus on recent methodological advances and results on specific strongly correlated materials (ruthenates, manganites, titanites, organics, bucky balls, heavy fermions and actinides etc.) Workshop is open to young research workers from all countries that are members of the United Nations, UNESCO or IAEA. Some funds are available for a limited number of people from developing countries. Deadline for receipt of request for participation form, March 31, 2000. Candidates should complete "Request for Participation" form (obtainable via e-mail smr1228@ictp.trieste.it or http://www.ictp.trieste.it/). Contact Ms. V. Shaw, Abdus Salam International Centre for Theoretical Physics, Workshop on Correlation Effects in Electronic Structure Calculations, Strada Costiera 11, I-34014 Trieste, Italy; telephone +39 040 2240541; telefax +39 040 224163; e-mail smr1228@ictp.trieste.it.
July 1 - 6, 2000: Future Perspectives of Superconducting Josephson Devices -- EuroConference on Physics and Applications of Multi-Junction Superconducting Josephson Devices, Aquafredda di Maratea, Italy. The conference will be dedicated to an advanced discussion of the present state-of-the-art and future perspectives of superconducting Josephson electronic devices with particular attention to their impact in technological and industrial applications. Sessions will provisionally include physics of superconducting Josephson devices, flux-flow and high-frequency devices, low-frequency devices and SQUIDs, RSFQ devices, and unconventional applications. Maximum 100 participants. A number of grants available for young scientists from European Community countries and Associated States. To apply, contact Josip Hendekovic, 2 quai Lezay- Marnesia, F-67080 Strasbourg Cedex, France; telephone +33 388 76 71 35; telefax +33 388 36 69 87; e-mail euresco@esf.org Web site http://www.esf.org/euresco/.
July 3 - 28, 2000: United States Summer School in Condensed Matter and Materials Physics, Boulder, Colo. New summer school for graduate students and postdocs in condensed-matter and materials physics has been established and will be held annually in Boulder. This first one is entitled Introduction to Superconductivity: Fundamentals and Applications. Main themes of the school will be basic principles of superconductivity, quantum dynamics of vortices and electrons, vortices in D > 2 and critical phenomena in superconductors, high-temperature and other unconventional superconductors, physics and applications of vortex dynamics, nonequilibrium superconductivity, mesoscopic and nanoscale superconducting systems, materials, applications, and devices. Application deadline, May 1, 2000. Most local expenses will be covered by the summer school (supported by the National Science Foundation, University of Colorado at Boulder, NIST, and Lucent). For further information, contact Z. Tesanovic, Department of Physics and Astronomy, 315 Bloomberg Center, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218-2686; telephone (410) 516-5391; telefax (410) 516-7239; e-mail cmsummer@pha.jhu.edu or zbt@pha.jhu.edu. For details and application forms see Web site http://www.indiana.edu/~uscmpsc/.
*Sept. 13 - 16, 2000: The Second International Conference on Inorganic Materials, University of California, Santa Barbara, Calif. Meeting will provide an opportunity to highlight recent developments and to identify emerging and future areas of growth in this field. Topics include electronic materials, structural materials and ceramics, biomaterials, intermetallics, catalytic, and porous materials. Emphasis on oral presentations by invited speakers combined with extended poster sessions. Abstract deadline, February 25, 2000. Official language is English. A tabletop exhibition will run for the duration of the conference. For information, contact Sarah Wilkinson, Second International Conference on Inorganic Materials, Elsevier Science Ltd., The Boulevard, Langford Lane, Kidlington, Oxford, OX5 1GB, United Kingdom; telephone +44 1865 843691; telefax +44 1865 843958; e-mail sm.wilkinson@elsevier.co.uk.
*Sept. 17 - 22, 2000: The Applied Superconductivity Conference (ASC 2000), Pavilion Convention Center, Virginia Beach, Virginia. Premier conference on applied superconductivity held every two years. The meeting will highlight the latest developments and will feature invited presentations that offer an exciting look into the future. Papers solicited in three general areas of superconductivity: large scale, materials, and electronics. Abstract deadline, February 11, 2000. All abstracts must be submitted electronically. Further information available at the Web site http://www.ascinc.org.
RESOURCES
Products and Services
New software: Virtual Instruments has recently announced development of new software for resistivity measurements. Ariadne is a software solution for applications involving measurements of the resistivity tensor of anisotropic conducting media by multiterminal technique. The method has evolved in recent years in response to the great interest in properties of such highly anisotropic materials as high-temperature superconductors, crystals exhibiting colossal magnetoresistance, etc. In this method, the electrical current is injected into a sample of a given geometry, and the voltage drops between pairs of voltage contacts attached to the surface of the sample are measured. Then, one has to find the distribution of the electrical potential inside the sample as a function of unknown components of the resistivity tensor and to solve numerically the inverse problem, thus determining these components from the measured voltages. This procedure is the main function of Ariadne. Free trial download is available. For information, contact Virtual Instruments, 150 East 39th Street, Suite 804, New York, NY 10016; e-mail info@virtinst.com Web site http://www.virtinst.com/.
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. 14, #3, February 1, 2000.