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  • resistivity
  • Springer  (13)
  • 1990-1994  (9)
  • 1985-1989  (4)
  • 1960-1964
  • 1950-1954
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  • 1
    Electronic Resource
    Electronic Resource
    Electron tunneling into high-T c cuprates: The case of Y1−x Pr x Ba2Cu3O7−δ (1994)
    Springer
    Journal of superconductivity 7 (1994), S. 345-348 
    Details
    ISSN: 1572-9605
    Keywords: Tunneling ; Y1−xPrxBa2Cu3O7−δ ; resistivity ; energy gap
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract Many different forms of superconducting tunneling have been attempted with the high-T c cuprates. For these studies to be convincing, it is important to assure that elastic tunneling is the dominant conduction mechanism in the structures considered. Some simple criteria to determine whether this is the case are reviewed, and then our results (which satisfy the criteria) on the system Y1−xPrxBa2Cu3O7−δ are discussed. In this study we show that with increasing Pr concentration, the material becomes more gapless.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00724566
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  • 2
    Electronic Resource
    Electronic Resource
    Temperature dependence of the infrared optical properties of YBa2Cu3O7: A plasmon damping model (1994)
    Springer
    Journal of superconductivity 7 (1994), S. 481-483 
    Details
    ISSN: 1572-9605
    Keywords: High-T c superconductors ; YBa2Cu3O7 ; infrared ; plasmon ; resistivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract The temperature dependence observed in the mid- and near-infrared optical properties of YBa2Cu3O7 is explained in terms of the Drude model for free charge carriers. In the Drude model, the linear temperature dependence of the dc resistivity arises from the free charge carriers having a temperature-dependent mean free path. This temperature dependence results in the plasmon contribution to the dielectric constant having a damping coefficient which also varies linearly with temperature. We find that the temperature dependence which is observed in the absorption and reflection spectra of YBa2Cu3O7 is consistent with this simple model.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00724594
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  • 3
    Electronic Resource
    Electronic Resource
    Anisotropic uniaxial pressure effects in YBa2Cu3O7−δ (1994)
    Springer
    Journal of superconductivity 7 (1994), S. 159-164 
    Details
    ISSN: 1572-9605
    Keywords: Uniaxial pressure dependence ; YBa2Cu3O7−δ ; resistivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract We present measurements of the uniaxial pressure dependence ofT c of untwinned YBa2Cu3O7−δ crystals with various oxygen stoichiometries. For all samples investigated,T c decreases for pressure alonga, increases for pressure alongb, and, in oxygen deficient samples, increases strongly for pressure alongc. These results are compared to the behavior found in the La2−x Sr x CuO4 and YBa2Cu4O8 systems. Neither the model of pressure-induced charge transfer nor coupling to orthorhombic distortions can explain all the data. However, the presence of singularities in the electronic density of states close to the Fermi energy is a possible origin of the observed behavior. Our preliminary data on the pressure dependence of thec-axis and in-plane resistivities in twinned crystals are consistent with this view.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00730387
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  • 4
    Electronic Resource
    Electronic Resource
    Electronic specific heat of Tl2Ba2CuO6+δ from 2 K to 300 K for 0≤δ≤0.1 (1994)
    Springer
    Journal of superconductivity 7 (1994), S. 261-264 
    Details
    ISSN: 1572-9605
    Keywords: Overdoped Tl2Ba2CuO6+δ ; electronic heat capacity ; resistivity ; pair breaking
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract Using a high-precision differential technique with a resolution of 1∶104, we have measured the heat capacity of Tl2Ba2CuO6+δ over a temperature range 2–300 K for 0≤δ≤0.1. Anomalies atT c are seen for all superconducting compositions measured, and the results are consistent with a temperature- andδ-independent normal-state electronic termγ n∼0.6 mJ/g-at. K2. The samples with the largerT c 's exhibit strong fluctuations in their specific heat, typical of a highly anisotropic 2D superconductor, but there is some evidence that these fluctuations become weaker atT c falls-consistent with an increase in the coherence length on hole doping. At temperatures below 5 K an upturn in the data is observed which appears to increase in magnitude asT c falls, correlating with the increase in the Curie term of published susceptibility data.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00730408
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  • 5
    Electronic Resource
    Electronic Resource
    Lattice and spin bipolarons in metal oxides and doped fullerenes (1994)
    Springer
    Journal of superconductivity 7 (1994), S. 599-605 
    Details
    ISSN: 1572-9605
    Keywords: Bipolarous ; spin ; NMR ; Hall effect ; resistivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract We extrapolate the BCS theory to the strong electron-phonon and (or) electron-spin fluctuation interaction and show that in the strong-coupling limit the ground state is a charged Bose liquid of lattice and (or) spin bipolarons. Kinetic and thermodynamic properties of charged bosons on a lattice in the normal and superconducting states are discussed, and some evidence for the model is given from NMR, neutron scattering, near-infrared absorption, Hall effect, resistivity, thermal conductivity, isotope effect, heat capacity, and critical magnetic fields of high-T c oxides. The maximum attainableT c is estimated to be in the region of the transition from the Fermi liquid to a charged Bose liquid (polaronic superconductivity). The proposed theory is not restricted by low dimensionality and might be applied to cubic oxides such as the “old” BaPbBiO and to alkali-doped C60 as well.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00728467
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  • 6
    Electronic Resource
    Electronic Resource
    The oxidation and resistance of tantalum-nitride thin films (1993)
    Springer
    Oxidation of metals 40 (1993), S. 5-20 
    Details
    ISSN: 1573-4889
    Keywords: sheet resistance ; resistivity ; oxidation ; tantalum nitride ; thin films
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The oxidation of reactively-sputtered, tantalum—nitride thin films has been studied between 473 and 773 K in air. Films with thicknesses that correspond to sheet resistances of 43, 75, and 150 Ω/□ were evaluated in this study. X-ray diffraction revealed that the films and the oxidation products were amorphous. The oxidation products were characterized with AES and XPS. The oxidation process was monitored by measuring the change in sheet resistance with time. Sheet resistance measurements were performed with a four-point probe. The oxidation kinetics can be represented by the equation ΔR/R n =k′t. ΔR/R is sheet resistance change in %, t is time, and k′ is the rate constant. The oxidation kinetics, for the thickest film, were parabolic above about 598 K, and approximately quartic below this temperature. The 75 Ω/□ films deviated from parabolic kinetics below 603 K, and approached approximate cubic kinetics at 498 K. However, the data were forced to fit parabolic kinetics with good correlation. For the thinnest film, no deviation from parabolic kinetics was observed. The rate constants obeyed the Arrhenius relation. An activation energy of 147 kJ/mole (1.52eV) was calculated, for the thickest film, during parabolic kinetics. This value is approximately equal to the activation energy obtained during quartic kinetics. A model that explains the deviation from parabolic to quartic oxidation kinetics at lower temperatures is presented. In this model, the change in resistance as a function of time was due to simultaneous change in film resistivity, as a result of oxygen dissolution into the film, and oxide-scale growth. The temperature at which this deviation occurs should be a function of film thickness.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00665256
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  • 7
    Electronic Resource
    Electronic Resource
    Resistivity and magnetic susceptibility studies of TlmCan−1Ba2CunOy before and after doping with LiF (1993)
    Springer
    Journal of superconductivity 6 (1993), S. 111-118 
    Details
    ISSN: 1572-9605
    Keywords: LiF-doped TlCaBaCuO ; resistivity ; susceptibility
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract Measurements of the superconducting resistance as a function of temperature were performed using the conventional four-probe method. The transition to complete superconductivity was recorded for samples of (Tl2Ca2Ba2Cu3O10)100−xLiF x (2223) mixed with different LiF ratiosx=0, 2, 4, 5, 6, 8, 10, and 12 wt.%. It was found that the transition temperatureT c was increased up to 5 wt.% of LiF. Further addition of LiF decreasesT c . Therefore, 5 wt.% LiF is the optimum concentration giving a transition temperature of 130 K. Measurements of the superconducting resistance of all the samples except the (1111) compound show that the addition of 5 wt.% LiF increasesT c and decreases the metastable phases. The real part of the a.c. magnetic susceptibilityϰ a.c. is studied using a zero-field cooled mechanism. The temperature dependence ofϰ a.c. for the prepared TlBaCaCuO having stoichiometric composition of (1111), (2223), (2234), and (3245) and that after doping with 5 wt.% LiF showed a broad feature. The transition to the complete diamagnetic state takes place in a broad transition region containing many transition steps, indicating the presence of metastable phases. The addition of LiF decreases the fluctuation in the transition region and its effect in reducing the number of multiphases.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00617810
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  • 8
    Electronic Resource
    Electronic Resource
    Phase-slip resistivity in high-temperature superconductors: a manifestation of intrinsic nano-granularity (1992)
    Springer
    Journal of superconductivity 5 (1992), S. 67-74 
    Details
    ISSN: 1572-9605
    Keywords: Flux flow ; phase slip ; Josephson junctions ; resistivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract Several critical experiments have shown that the so-called “background” magnetoresistance which occurs with no Lorentz force activation is isotropic in thea-b plane. This isotropic resistivity is linked to paradoxical behavior of vortices which cannot be changed by pinning, a result which may imply intrinsic pinning. Nevertheless, a number of flux-flow observations indicate that vortices may also behave as if they were unpinned. An explanation is proposed which states that this behavior arises as a consequence of defects in oxygen ordering in the Cu-O planes of HTSC crystals; this explanation involves segmentation of the Cu-O planes, and Josephson coupling between adjacent segments. The effective junction areas are seen to be very small, with dimensions characteristic of the size of the unit cell. Thermal motion of nano-scale weak links resolves the pinning paradox by inducing phase-slip resistive dissipation. The resulting phase-slip resistivity is shown to have axial symmetry, that is, the resistivity is independent of the angle between the current and the applied field, with both in thea-b plane.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00617998
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  • 9
    Electronic Resource
    Electronic Resource
    Earthquake prediction in northeast India—A review (1991)
    Springer
    Pure and applied geophysics 136 (1991), S. 297-313 
    Details
    ISSN: 1420-9136
    Keywords: Precursor ; resistivity ; magnetic ; gravity ; earthquake swarm ; microseismicity-rate ; velocity-ratio ; radon gas
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract A multidimensional geophysical approach is made to study earthquake precursors in northeast India. Resistivity, gravity and seismological precursor anomalies for the two recent damaging earthquakes, one on December 30, 1984, magnitude 5.8, and the other on August 6, 1988, magnitude 7.5, are very encouraging to intensify these studies in the region. Improved methods of magnetic and geohydrological precursor studies are suggested.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00876379
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  • 10
    Electronic Resource
    Electronic Resource
    High-temperature properties of the Bi-Sr-Ca-Cu-O system: Simultaneous occurrence of melting, oxygen desorption, and a metal-insulator transition (1988)
    Springer
    Journal of superconductivity 1 (1988), S. 407-415 
    Details
    ISSN: 1572-9605
    Keywords: high-T c superconductivity ; resistivity ; melting ; oxygen desorption ; metal-insulator transition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract We have investigated the temperature dependence of the electrical transport and the thermogravimetric properties, from -200°C to +1000Ć, of the Bi-Sr-Ca-Cu-O high-temperature superconductor. We conclude that this system has a cooperative, simultaneous-melting/oxygen desorption/metal-insulator transition that occurs near 900°C. We speculate on its nature and on its relationship to phenomena found in other high-T c superconductors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00618597
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  • 11
    Electronic Resource
    Electronic Resource
    Thermoelectric power measurements of YBa2Cu3O7−δ up to 950°C and their application to test the band structure near EF (1988)
    Springer
    Journal of superconductivity 1 (1988), S. 53-61 
    Details
    ISSN: 1572-9605
    Keywords: YBa2Cu3O7−δ ; resistivity ; thermoelectric power
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract Four-probe resistivity (ρ) and thermoelectric power (TEP) measurements were carried out on samples of YBa2Cu3O7−δ up to 950°C, in air and in flowing oxygen at 1 bar. Below 700 K the TEP is small and increases rapidly above it, reaching, at 1200 K, +140μV/K in air and +120μV/K in oxygen. At the changeover temperature (700 K) the slope of logρ vs.T changes abruptly. These results are interpreted in terms of a model of transport of carriers in a narrow band, which is full forδ = 1 and half-filled forδ = 0. Possible origins for such a narrow band are discussed in detail.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00617951
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  • 12
    Electronic Resource
    Electronic Resource
    Comparison of Y-Ba-Cu-O compounds prepared from BaCuO2 and Ba2Cu3O5+δ (1988)
    Springer
    Journal of superconductivity 1 (1988), S. 451-461 
    Details
    ISSN: 1572-9605
    Keywords: Y-Ba-Cu-O ; BaCuO2 ; Ba2Cu3O5+δ ; resistivity ; superconducting phases ; baseline hysteresis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract Series of Y-Ba-Cu-O compositions were prepared from barium cuprates and Y2O3, using a two-step synthesis route. It has been shown that Ba2Cu3O5+δ is essential in formation of the YBa2Cu3O7−δ superconducting phase while BaCuO2 is not an appropriate starting material. A wide composition range fromx=2 to 17 was prepared from Ba2Cu3O5+δ in the YBa x Cu1.5x O z series without disappearance of macroscopic superconductivity atT c〉77 K. Resistivity measurements hint at the existence of two superconducting phases. ESR investigations revealed a baseline hysteresis, depending on the actual value ofx.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00618601
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  • 13
    Electronic Resource
    Electronic Resource
    Resistivity and induced polarization response of a thin sheet (1985)
    Springer
    Pure and applied geophysics 123 (1985), S. 882-892 
    Details
    ISSN: 1420-9136
    Keywords: thin sheet ; induced polarization ; resistivity ; borehole ; conductive slab ; dilution factor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The relevant potential theory is given for a current point source in the presence of a conductive slab embedded in a homogeneous host region of infinite extent. The thin sheet representation is obtained from the exact integral formulation by a simple mathematical limit process. The same result is also deduced directly at the outset by applying a thin sheet boundary condition. The apparent resistivity for a two electrode array is then computed for the case where the bore hole intersects the thin sheet at right angles. The corresponding results for the dilution factor, relevant to the induced polarization response, are also obtained. It is shown that the apparent resistivity and the dilution factor are constant when the potential and the current electrode straddle the sheet but there is a characteristic decrease as the electrodes move away from the sheet.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00876976
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