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  • 1
    Electronic Resource
    Electronic Resource
    Reentrant phenomena in superconductivity of ultrathin amorphous bismuth films (1989)
    Springer
    Journal of low temperature physics 75 (1989), S. 331-347 
    Details
    ISSN: 1573-7357
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Quasi-reentrant phenomena in superconductivity conditioned by the mechanisms of phase coherence in inhomogeneous two-dimensional systems are studied on ultrathin amorphous films of bismuth. The effects are shown to be appreciably dependent on the film structures. For films of nearly island structure (L≲10 Å), the effects can be attributed to competition of Josephson and single-particle tunneling of electrons. Thicker films (10 Å ≲L≲15 Å) are equivalent to the system of Josephson junctions corresponding to the resistively shunted junction model. In this case the quasi-reentrant phenomena are due to the quantum phase fluctuations and macroscopic tunneling. The influence of quantum phase fluctuations is considered (in contrast to the known previous investigations) by involving not only nonmonotone temperature dependences of resistanceR but also nonmonotone dependencesR(I), R(V) andR(H) obtained for the first time for ultrathin films (I being the current,V the voltage applied, andH the perpendicular magnetic field).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00683711
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  • 2
    Electronic Resource
    Electronic Resource
    Superconductivity effects near the metal-insulator transition in granular indium films (1987)
    Springer
    Journal of low temperature physics 69 (1987), S. 401-417 
    Details
    ISSN: 1573-7357
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The paper reports on an investigation of the electric resistance as a function of temperatureT, magnetic fieldH, and applied voltageV in granular indium films when approaching the metal-insulator transition (MIT) due to increased thickness of the oxide layers between granules. The dependences are shown to be governed atT≤5 K by competition of the hopping conductivity and the Josephson tunneling of electrons, sometimes giving rise to a resistance minimum inR(T) associated with superconductivity. It was also found that even when the intergranular Josephson tunneling is totally suppressed, transition of granules to the superconducting state influences essentially the dependencesR(T, H), changing the functional form ofR(T) and resulting in anomalously high negative magnetoresistance. This is shown to stem from the change of the character of activated electron tunneling as the granules become superconducting.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00683330
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  • 3
    Electronic Resource
    Electronic Resource
    Quench-condensed indium-hydrogen films. II. Changes in electric and superconducting characteristics near the metal-insulator transition (1984)
    Springer
    Journal of low temperature physics 54 (1984), S. 587-605 
    Details
    ISSN: 1573-7357
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Electrical and superconducting properties of indium films condensed in a H2 atmosphere (pressurep H 2=6×10−6 to 1.4×10−4 Torr) onto a substrate cooled with liquid helium are investigated. As hydrogen content is increased, a continuous increase in residual resistivity ρ* is observed, permitting systematic study of the resistance vs. temperature dependenceR(T) and the superconducting transition temperatureT c on approaching the metal-insulator transition (MIT). With regard to ρ*, four regimes of conductivity can be observed: (1) conductivity with a positive temperature resistance coefficient (TRC), (2) conductivity with a small, constant, negative TRC, (3) conductivity under weak localization with ΔR (T) ∼ln T or $$ \sim \sqrt T $$ type corrections, (4) hopping conductivity.T c rises continuously with ρ* and reaches its peak (∼5.2K) in the second regime. A further increase of ρ* leads to a decrease ofT c and complete suppression of superconductivity. The experimental dependenceR(T) is compared with theory. TheT c variation on approaching the MIT and the relation between Mooij's rule and the superconducting properties are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00683621
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  • 4
    Electronic Resource
    Electronic Resource
    Quench-condensed indium-hydrogen films. I. Superconductivity enhancement and metastable state formation (1984)
    Springer
    Journal of low temperature physics 54 (1984), S. 1-14 
    Details
    ISSN: 1573-7357
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The electrical and superconducting properties of indium films are studied. The films were condensed in H2 atmosphere ( $${\text{p}}_{{\text{H}}_{\text{2}} } $$ ranged from 4×10−7 to 6×10−5 Torr) onto a substrate cooled with liquid helium down to about 3 K. As the hydrogen concentration increased, the normal resistivity ρ n of the films continuously increased up to a point where the metal-insulator transition occurred. It was found for the first time that saturation of In films with hydrogen lead to a significant increase (up to ∼5.15 K) inT c and to zero-dimensional paraconductivity aboveT c . Possible mechanisms for an effect of dissolved hydrogen on ρ n andT c are considered along with the influence of structural defects onT c . At $${\text{p}}_{{\text{H}}_{\text{2}} } $$ 〉2×10−6 Torr the prepared films appear to be a metastable phase In(H) with high nonequilibrium hydrogen concentration, which decayed at ∼ 5 K. The destruction of In(H) was accompanied by a release of H2 from the film, a sharp drop of resistance (by three and more orders of magnitude), and a rise inT c . The properties and the formation and stabilization conditions of the In(H) phase are considered in detail and this phase is compared with the a-Bi(H) phase observed earlier.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00681473
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  • 5
    Electronic Resource
    Electronic Resource
    Weak localization and fluctuation electron-electron interaction in disordered indium films (1985)
    Springer
    The European physical journal 58 (1985), S. 111-116 
    Details
    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The effects of perpendicular magnetic fieldsH on the temperature dependence of the resistanceR(T) (T〈20 K), the superconducting transition temperatureT c and the fluctuation superconductivity (T«T c ) have been investigated on high-resistance (R □〉1 kOhm) indium films prepared by simultaneous condensation of the metal and hydrogen onto a substrate cooled to 5 K. AtT«T c the resistance slightly decreased with rising temperature, in agreement with the weak localization and electron-electron interaction (EEI) theories. Processing of theR(T, H) curves in terms of the theories permitted the electron phase relaxation time τϕ(T) to be determined and the time τ so of electron spin relaxation due to spin-orbital interaction (SOI) to be estimated. In the temperature rangeT−T c ≫ħ/kτϕ the effect of the fluctuation EEI on conductivity was investigated. The contribution of the fluctuation EEI is shown to be given by a sum of two corrections: the Cooper and the Maki-Thompson ones. In the rangeT−T c ≪ħ/kτϕ the influence of magnetic field was investigated on the transition from two-to zerodimensional fluctuations of the order parameter resulting from temperature increase in the rangeT〉T c . Increasing field was found to cause enlargement of the zero-dimensional fluctuation critical region and lowering of the fluctuation dimensionality alteration temperature, leading eventually to complete two-dimensional fluctuation suppression. The experimental dependencesT c (H) experienced, in addition to orbital effects of the magnetic field, depairing effect of the field on electron spins. Thus the τ so magnitude could also be estimated and proved roughly equal to τ so determined from the analysis ofR(T, H)
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01304262
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  • 6
    Electronic Resource
    Electronic Resource
    The influence of hydrogen on the atomic distribution function and electrical resistance of amorphous chromium films (1989)
    Springer
    The European physical journal 75 (1989), S. 51-58 
    Details
    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Electrical resistivity of amorphous chromium films (20–37 nm thick) deposited in a hydrogen atmosphere (P H 2=8·10−6–2·10−4 hPa) onto a substrate cooled by liquid helium down to ≈ 2 K is measured, and electron-diffraction studies have been performed immediately after the quench condensation and after annealing to different temperatures up to 300 K. The preparation method employed permits a considerable hydrogen enrichment of the films to be reached. The maximum hydrogen concentration corresponds approximately to a stoichiometric composition of CrH. It is found that as the maximum concentration is approached the atomic distribution functionG(r) changes remarkably. The interatomic distances increase considerably (by 10%) and the atomic densities decrease. It is quite possible that amorphous chromium hydride is a final state with the maximum hydrogen concentration. For films with intermediate concentration,G(r) is found to vary substantially under annealing up to ≈90 K. The electron-diffraction and electronmicroscopic data, as well as the variations in resistivity due to annealing, suggest that with annealing up to ∼90 K, a hydrogen redistribution occurs in the amorphous films, initially homogenous in concentration. We observe also distinct indications of separation into phases with increased and reduced hydrogen contents.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01313567
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  • 7
    Electronic Resource
    Electronic Resource
    Effect of grain boundary scattering on the TCR of thin tin films (1983)
    Springer
    Journal of materials science 2 (1983), S. 360-362 
    Details
    ISSN: 1573-4811
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00726330
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