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IBM Journal of Research and Development

Issue 1 • Jan. 1962

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Displaying Results 1 - 25 of 31
  • Foreword to papers in this issue [Fundamental Research in Superconductivity]

    Publication Year: 1962, Page(s): 2
    IEEE is not the copyright holder of this material | PDF file iconPDF (166 KB)
    Freely Available from IEEE
  • Review of the Present Status of the Theory of Superconductivity

    Publication Year: 1962, Page(s):3 - 11
    Cited by:  Papers (2)
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (741 KB)

    Theory and experiment are compared for a number of phenomena in superconductors. While the agreement is generally good, there are some discrepancies for which there is no adequate explanation. View full abstract»

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  • On the Influence of Free Path on the Meissner Effect

    Publication Year: 1962, Page(s):12 - 13
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (302 KB)

    The influence of impurities on the behaviour of a superconductor is computed by introducing a scattering potential and averaging over all positions of the scattering centers. This procedure only takes into account scattering and free path effects and neglects changes in the elastic constants and electron density due to actual impurities. Using perturbation theory, it is shown that the free energy ... View full abstract»

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  • Solutions of the BCS Integral Equation and Deviations from the Law of Corresponding States

    Publication Year: 1962, Page(s):14 - 23
    Cited by:  Papers (2)
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (795 KB)

    The BCS integral equation has been studied for nonseparable interactions of the Bardeen-Pines form, V(|εε’|). Numerical solutions were obtained using an IBM 7090 for a simple interaction of this form which included the effect of the Coulomb repulsion. The results for the ratio of the energy gap to the critical temperature and for the temperature dependence of the... View full abstract»

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  • Nuclear Spin Relaxation in Superconducting Cadmium

    Publication Year: 1962, Page(s):24 - 26
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (415 KB)

    The nuclear spin-lattice relaxation time, T1, in superconducting cadmium has been measured in the range of 0.37°K to 0.6°K. A field-cycling method was used. The results are explained by the theory of Bardeen, Cooper, and Schrieffer, and give another confirmation of the theory. The temperature dependence of T1 in cadmium is identical to that in aluminum, which is... View full abstract»

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  • Experimental Work on Superconductivity

    Publication Year: 1962, Page(s):27 - 30
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (473 KB)

    The high thermal conductivity in the superconductive state at low reduced critical temperatures has been used for the detection of metal imperfections, including those caused by radiation damage. A statistically disordered single crystal of Ta with 30% Nb has also been investigated. Work is described on specific heats, ultrasonic attenuation and on the behaviour of thin superconductive films. An e... View full abstract»

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  • The Kapitza Resistance of Metals in the Normal and Superconducting States

    Publication Year: 1962, Page(s):31 - 33
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (341 KB)

    A calculation has been made of the transfer of heat across a metal-liquid helium interface. In the normal state an appreciable transfer of energy occurs directly from the conduction electrons to the phonons of the fluid. Three mechanisms have been considered: the phonon-electron interaction within the metal, the modulation of the position of the interface and the phonon-electron interaction of the... View full abstract»

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  • Superconductivity and Electron Tunneling

    Publication Year: 1962, Page(s):34 - 43
    Cited by:  Papers (5)
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (776 KB)

    Experiments on the tunneling of electrons through a thin dielectric layer separating two superconducting metals are reported. Data are presented for the pairs Al-Pb, Sn-Pb, and In-Sn. Particular attention is paid to the form of the tunneling current vs voltage characteristics and to the changes observed as a function of temperature. Experimental details relative to the measurement techniques, the ... View full abstract»

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  • Magnetic Field Dependence of the Superconducting Energy Gap in Ginzburg-Landau Theory with Application to Al

    Publication Year: 1962, Page(s):44 - 48
    Cited by:  Papers (1)
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (507 KB)

    A theoretical calculation is given of the magnetic field dependence of the superconducting energy gap, using the Ginzburg-Landau theory. In addition to depending upon the size of the specimen, the field dependence of the energy gap depends quite strongly on the nature of the boundary conditions. For the usual case with the magnetic field equal on opposite sides of a film, the calculations show tha... View full abstract»

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  • Dependence of the Energy Gap in Superconductors on Position and Magnetic Field

    Publication Year: 1962, Page(s):49 - 54
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (654 KB)

    A review is given of work concerning the decrease of the energy gap in superconductors when a magnetic field is applied. The absence of any observable effect in previous spectroscopic work is explained, and conditions for large effects are outlined. Experimental measurements on thermal conductivity and microwave absorption in films in a magnetic field are described. The results show that in thin f... View full abstract»

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  • Far-Infrared Absorption in a Lead-Thallium Superconducting Alloy

    Publication Year: 1962, Page(s):55 - 57
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (394 KB)

    Preliminary measurements have been made of the absorption of far-infrared radiation in the surface of a bulk superconducting alloy composed of lead with 10.0 atomic percent thallium at 1.4K. The results indicate that the gap edge is quite distinct, in contrast to previous results of Richards and Tinkham on other alloys. The sharpness of the gap edge is thought to be characteristic of alloys which ... View full abstract»

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  • Ultrasonic Attenuation in Superconductors

    Publication Year: 1962, Page(s):58 - 62
    Cited by:  Papers (1)
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (456 KB)

    A brief review is given of the ultrasonic attenuation in metals arising from direct interaction of the elastic waves and conduction electrons, and the physical variables on which it depends. The drop in attenuation of longitudinal waves on entering the superconducting state is in good agreement with BCS theory, the various factors combining to make the relative attenuation, αs/&#... View full abstract»

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  • The Magnetic Behavior of Superconductors of Negative Surface Energy

    Publication Year: 1962, Page(s):63 - 67
    Cited by:  Papers (5)
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (540 KB)

    Abrikosov and the author have separately suggested that a new type of reversible magnetic behavior is to be expected in superconductors whose coherence length is small compared with their penetration depth. The treatments of these two authors are shown to lead to similar results for pure metals and to only slightly different results for alloys. The experimental evidence in favor of a new type of r... View full abstract»

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  • Effects of Electron Concentration and Mean Free Path on the Superconducting Behavior of Alloys

    Publication Year: 1962, Page(s):68 - 70
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (326 KB)

    A brief review is given of the superconducting behaviour of solid-solution alloys. Intermetallic compounds are not considered but some reference is made to secondary solid solutions. Two topics are discussed: some factors affecting the transition temperature, and the role played by surface energy between normal and superconducting regions. View full abstract»

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  • Surface Energy Effects at the Boundary between a Superconductor and a Normal Conductor

    Publication Year: 1962, Page(s):71 - 74
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (375 KB)

    Films of tin ranging from 500 to 1400 Å in thickness have been prepared in pairs by vacuum deposition onto rotating cylindrical glass and metal substrates. The temperature dependence of the critical fields has been measured. The critical temperatures of the films on metal substrates are all depressed. Their critical fields at absolute zero, however, are usually not depressed but can be high... View full abstract»

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  • Some Elementary Theoretical Considerations Concerning Superconductivity of Superimposed Metallic Films

    Publication Year: 1962, Page(s):75 - 76
    Cited by:  Papers (1)
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (337 KB)

    A microscopic theory of superconductivity of superimposed metallic films is proposed, based on the fact that the electron pair correlation function penetrates into a normal metal where the electron-electron interaction would not by itself produce a superconducting state. View full abstract»

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  • Thermodynamic Consistency of Magnetic and Calorimetric Measurements on Superconductors

    Publication Year: 1962, Page(s):77 - 81
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (493 KB)

    Comparison of the entropy and specific heats of normal and superconducting tin and indium as computed from critical field and calorimetric measurements shows excellent consistency. Salient features of the comparison are briefly summarized. Some implications of the recently reported specific heat anomaly for indium are discussed. View full abstract»

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  • The Temperature and Pressure Dependence of Critical Field Curves

    Publication Year: 1962, Page(s):82 - 83
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (319 KB)

    A brief discussion is given of the analysis of recent critical field measurements. In particular, a negative volume coefficient of thermal expansion is predicted for tin in the superconducting state. View full abstract»

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  • Mechanical Effects at the Superconducting Transition

    Publication Year: 1962, Page(s):84 - 88
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (497 KB)

    Work in Zürich on the difference in size and in expansion coefficient between the normal and the superconducting states is summarized. The volume dependences of the critical temperature and of the electronic density of states at the Fermi surface are discussed. View full abstract»

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  • Variation of the Elastic Moduli at the Superconducting Transition

    Publication Year: 1962, Page(s):89 - 93
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (416 KB)

    Using an ultrasonic technique capable of measuring changes in the elastic moduli as small as one part in 107, the small modulus changes associated with the normal-to-superconducting transition have been measured as a function of both temperature and magnetic field. Single-crystal specimens of the cubic metals Pb, V, Nb and Ta were used and all their elastic moduli measured so that chang... View full abstract»

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  • First- and Second-Order Stress Effects on the Superconducting Transitions of Tantalum and Tin

    Publication Year: 1962, Page(s):94 - 111
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (1398 KB)

    The shift of critical field of a single-crystal wire under uniaxial tension is studied for Ta and Sn. For Ta the shift is nonlinear and gives both the first-order critical field-stress coefficient and a particular combination of second-order coefficients. By combining with other data, the three second-order constants are estimated. The smaller first-order coefficient of Sn is found to be considera... View full abstract»

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  • Thermal Conductivity of Dilute Indium-Mercury Superconducting Alloys

    Publication Year: 1962, Page(s):112 - 115
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (437 KB)

    Thermal conductivities were measured for a series of polycrystalline alloys of indium containing 0.1 to 2.5 At.% mercury. Using theoretical models which relate the electronic thermal conductivity of a superconductor to its energy gap, the temperature and composition dependences of the energy gap have been calculated for these specimens. Estimates of the lattice thermal conduction were also obtaine... View full abstract»

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  • The Superconductivity of Some Intermetallic Compounds

    Publication Year: 1962, Page(s):116 - 118
    Cited by:  Papers (1)
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (374 KB)

    The W-Os, Re-W, Re-Mo, Re-Hf, and Mo-Hf binary systems were investigated for superconductivity down to 1°K. Several new superconducting regions were found with the most significant occurring in the primary and terminal solid-solution alloys. The occurrence of superconductivity in the β-phase field of the Re-Hf and Mo-Hf binaries indicates a possible explanation for the spurious super... View full abstract»

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  • High-Field Superconductivity in Some bcc Ti-Mo and Nb-Zr Alloys

    Publication Year: 1962, Page(s):119 - 121
    Cited by:  Papers (1)
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (434 KB)

    Zero electrical resistance at unusually high magnetic field strengths has been observed in the bcc alloys Ti-16 a/o (atomic percent) Mo, Nb-12 a/o Zr, and Nb-25 a/o Zr. The maximum high-field zero-resistance current density, Jc, in these alloys appears to be a sensitive function of temperature, the degree of cold-working, and the orientation of the applied transverse magnetic field. For... View full abstract»

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  • Anomalous Resistive Transitions and New Phenomena in Hard Superconductors

    Publication Year: 1962, Page(s):122 - 125
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (441 KB)

    The value of the critical current (Ic)-critical field (Hc) of cold-worked Nb, Mo-Re and Nb-Zr wires at constant temperature is not a single-valued function of the field and current direction. The previous history of a specimen during an experiment plays an important role and a measurement of the critical field-critical current value can influence the response of the specimen ... View full abstract»

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The IBM Journal of Research and Development is a peer-reviewed technical journal, published bimonthly, which features the work of authors in the science, technology and engineering of information systems.

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Editor-in-Chief
Clifford A. Pickover
IBM T. J. Watson Research Center