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Soft Transverse Phonons in an Amorphous Metal

  • B. Golding
  • B. G. Bagley
  • F. S. L. Hsu

Abstract

In the search for high-transition-temperature superconductors it has been recognized that low atomic vibrational frequencies can lead to an enhancement of T c .1 Experiments have shown that thin-film superconductors prepared in a micro-crystalline or amorphous state, generally by vacuum deposition at cryogenic temperatures, can have a higher T c than the corresponding crystalline films.2 It has been proposed that the changes in T c in these films arise primarily from the lowering of vibrational frequencies upon disordering.3, 4 There are, however, a number of distinct mechanisms for lowering these frequencies, so that in any given film one or more mechanisms may be operative. For example, in both microcrystalline or amorphous films low vibrational frequencies may arise from localized modes at surfaces or internal structural discontinuities (grain boundaries or voids) or from propagating surface modes. Another source of low frequencies is the high defect concentrations of evaporated films, which tend to lower bulk phonon frequencies via a change in average mass density.

Keywords

Bulk Modulus Amorphous Metal Transverse Phonon High Defect Concentration Transverse Acoustic Mode 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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References

  1. 1.
    W.L. MacMillan Phys. Rev. 167, 331 (1968).Google Scholar
  2. 2.
    W. Biickel and R. Hilsch, Z. Phys. 131, 420 (1952); 138, 109 (1954).CrossRefGoogle Scholar
  3. 3.
    J.W. Garland, K.H. Bennemann, and F.M. Mueller, Phys. Rev. Lett. 21, 1315 (1968).ADSCrossRefGoogle Scholar
  4. 4.
    M. Strongin, O.F. Kammerer, J.E. Crow, R.D. Parks, D.H. Douglass, Jr., and M.A. Jensen Phys. Rev. Lett. 21, 1320 (1968).CrossRefGoogle Scholar
  5. 5.
    B. Golding, B.G. Bagley, and F.S.L. Hsu, Phys. Rev. Lett. 29, 68 (1972).ADSCrossRefGoogle Scholar
  6. 6.
    D. Weaire, M.F. Ashby, J. Logan, and M.J. Weins Acta Met. 19, 779 (1971).Google Scholar
  7. 7.
    J.D. Leslie, J.T. Chen, and T.T. Chen, Can. J. Phys. 48, 2783 (1970).ADSCrossRefGoogle Scholar
  8. 8.
    S. Ewert Z. Phys. 237, 47 (1970).ADSCrossRefGoogle Scholar
  9. 9.
    S. Ewert and W. Sander Z. Phys. 247, 21 (1971).Google Scholar
  10. 10.
    H. Happel, K. Knorr, and N. Barth Z Phys. 249, 185 (1971).ADSCrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media New York 1974

Authors and Affiliations

  • B. Golding
    • 1
  • B. G. Bagley
    • 1
  • F. S. L. Hsu
    • 1
  1. 1.Bell LaboratoriesMurray HillUSA

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