Phonon Spectrum of La

  • L. F. Lou
  • W. J. Tomasch


With improvements in diode fabrication techniques, values of 2Δ/kT c obtained with La films via tunneling have steadily increased1–5 from 1.6 to the full bulk value (this work) of 3.7–3.8.6,7 Nevertheless, tunneling studies continue to indicate an absence of strong structure directly attributable to f-band effects,8,9 revealing instead only modest deviations from the BCS tunneling density of states (TDS) reminiscent of phonon-induced structure described by strong-coupling theory. These observations suggest that strong-coupling theory may provide an adequate description of La, permitting a phonon spectrum α2F(w) to be extracted by the method of McMillan and Rowell.10 Effects due to f levels89 would presumably be reflected in anomalous values of λ(electron—phonon coupling strength) or µ* (effective Coulomb pseudopotential) obtained in the course of computing α2F(ω). McMillan’s approximate solution of the Eliashberg equations11,12 can then be used to calculate T c from λ, ,<ω>, and µ*. Failure to obtain agreement with observed values of T c would indicate difficulties with either the tunneling data or the applicability of strong-coupling theory.


Phonon Spectrum Strong Structure Derivative Data Compute Spectrum Full Bulk 
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.


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. 1.
    A.S. Edelstein and A.M. Toxen, Phys. Rev. Lett. 17, 196 (1966).ADSCrossRefGoogle Scholar
  2. 2.
    J.J. Hauser, Phys. Rev. Lett. 17, 921 (1966).ADSCrossRefGoogle Scholar
  3. 3.
    J.S. Rogers and S.M. Khana, Phys. Rev. Lett. 20, 1284 (1968).ADSCrossRefGoogle Scholar
  4. 4.
    A.S. Edelstein, Phys. Rev. 164, 510 (1967).ADSCrossRefGoogle Scholar
  5. 5.
    L.Y.L. Shen, Superconductivity in d- and f-Band Metals, (AIP Conf. Proc. No. 4) D.H. Douglass, Jr., ed., American Instituteof Physics, New York (1972), p. 31.Google Scholar
  6. 6.
    D.L. Johnson and D.K. Finnemore, Phys. Rev. 158, 376 (1967).ADSCrossRefGoogle Scholar
  7. 7.
    H.J. Levenstein, V.G. Chirba, and J.E. Kunzler, Phys. Lett. 24, A362 (1967).ADSCrossRefGoogle Scholar
  8. 8.
    J. Kondo, Progr. Theoret. Phys. (Kyoto) 29, 1 (1963).CrossRefGoogle Scholar
  9. 9.
    C.G. Kuper, M.A. Jensen, and D.C. Hamilton, Phys. Rev. 134, Al5 (1964).Google Scholar
  10. 10.
    W.L. McMillan and J.M. Rowell, Superconductivity, R.D. Parks, ed., Marcel Dekker, New York (1969), Vol. 1, p. 561.Google Scholar
  11. 11.
    W.L. McMillan, Phys. Rev. 167, 331 (1968).ADSCrossRefGoogle Scholar
  12. 12.
    R.C. Dynes, Phys. Rev. 2, 644 (1970).ADSCrossRefGoogle Scholar
  13. 13.
    J. Vrba and S.B. Woods, Phys. Rev. 2, B2243 (1971).ADSGoogle Scholar
  14. 14.
    W.T. Ziegler, R.A. Young, and A.L. Floyd, Jr., J. Am. Chem. Soc. 75, 1215 (1953).CrossRefGoogle Scholar
  15. 15.
    W.N. Hubin, Technical Report No. 182, Department of Physics, University of Illinois (1970).Google Scholar
  16. 16.
    J.M. Rowell, W.L. McMillan, and R.C. Dynes, “A Tabulation of Electron—Phonon Interaction in Superconducting Metals and Alloys. Part P” (to be published).Google Scholar

Copyright information

© Springer Science+Business Media New York 1974

Authors and Affiliations

  • L. F. Lou
    • 1
  • W. J. Tomasch
    • 1
  1. 1.Department of PhysicsUniversity of Notre DameNotre DameUSA

Personalised recommendations