Excitations in Quantum Boson Fluids

  • M. Saarela

Abstract

Excitations in the superfluid 4He have been an interesting subject of studies for decades.’ Yet, recently precise measurements of excitations in thin films2have created new interest in the possible excitation mechanisms in reduced dimensions. A thin 4He film adsorbed on strongly binding substrates like lithium, solid hydrogen, magnesium or solid helium on graphite forms a pronounced layered structure with one atomic layer thickness.3,4 The fluid within the first layer can well be approximated with a two-dimensional fluid. The energy gap between the lowest two single particle states perpendicular to the surface is between 7 and 13 Kelvins on these substrates. That makes it possible to observe clearly the collective, two-dimensional phonon - roton mode within the layer5 With the increasing layer density that mode turns into the ripplonlike surface mode. In the case of very thick films the lowest energy mode at small k is the ripplon mode and the higher lying layer modes merge into the three-dimensional phonon-roton mode.

Keywords

Vortex Magnesium Graphite Lithium Helium 

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. 1.
    R.P. Feynman, Phys. Rev. 94:262(1954).ADSCrossRefMATHGoogle Scholar
  2. 2.
    H.J. Lauter, H. Godfrin, V.L.P. Frank, and P. Leiderer, Phys. Rev. Lett. 68:2484 (1992).ADSCrossRefGoogle Scholar
  3. 3.
    B.E. Clements, J.L. Epstein, E. Krotscheck, and M. Saarela, Phys. Rev. B48:7450 (1993).ADSCrossRefGoogle Scholar
  4. 4.
    B.E. Clements, H. Forbert, E. Krotscheck, and M. Saarela, J. Low Temp. Phys. 95:849(1994).ADSCrossRefGoogle Scholar
  5. 5.
    B.E. Clements, H. Forbert, E. Krotscheck, H.J. Lauter, M. Saarela, and C.J. Tymczak, Phys. Rev. B50:6958(1994).ADSCrossRefGoogle Scholar
  6. 6.
    J.M. Kosterlitz and D.J. Thouless, J. Phys. C6:1181(1973).ADSGoogle Scholar
  7. 7.
    M. Saarela and F.V. Kusmartsev, Physica B194–196:617(1994).ADSGoogle Scholar
  8. 8.
    M. Saarela, B.E. Clements, E. Krotscheck, and F. V. Kusmartsev, J. Low Temp. Phys. 93:971(1993).ADSCrossRefGoogle Scholar
  9. 9.
    Shou-Cheng Zhang, Phys. Rev. Lett. 71:2142(1993).ADSCrossRefGoogle Scholar
  10. 10.
    M.T. Chen, J.M. Roesler, and J.M. Mochel, J. Low Temp. Phys. 89:125(1992).ADSCrossRefGoogle Scholar
  11. 11.
    B.E. Clements, H.J. Lauter, and H. Godfrin, private communication.Google Scholar
  12. 12.
    P.A. Whitlock, G.V. Chester, and M.H. Kalos, Phys. Rev. B38:2418(1988).ADSCrossRefGoogle Scholar
  13. 13.
    M. Saarela and J. Suominen, in: “Condensed Matter Theories,” Vol. 4, J. Keller,ed., Plenum, New York (1989), p. 377.Google Scholar
  14. 14.
    R.J. Donnelly, “Quantized Vortices in Helium II,” Cambridge University Press, Cambridge (1991).Google Scholar
  15. 15.
    A.D. Jackson, B.K. Jennings, A. Lande, and R.A. Smith, Phys. Rev. B24:105(1981).ADSCrossRefGoogle Scholar
  16. 16.
    R.A. Aziz, V.P.S. Nain, J.C. Carley, W.J. Taylor, and G.T. McConville, J. Chem. Phys. 70:4330(1979).ADSCrossRefGoogle Scholar
  17. 17.
    E. Feenberg, “Theory of Quantum Liquids,” Academic, New York (1969).Google Scholar
  18. 18.
    E. Krotscheck and M. Saarela, Phys. Rep. 232:1(1993).ADSCrossRefGoogle Scholar
  19. 19.
    M. Saarela and F.V. Kusmartsev, in: “Condensed Matter Theories,” Vol. 8, L. Blum and F.B. Malik, ed., Plenum, New York (1993) p. 173.CrossRefGoogle Scholar
  20. 20.
    J. Bardeen and G. Baym, and D. Pines, Phys. Rev. 156:207(1967).ADSCrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media New York 1995

Authors and Affiliations

  • M. Saarela
    • 1
  1. 1.Department of Theoretical PhysicsUniversity of OuluOuluFinland

Personalised recommendations