Neutron Spectroscopy in RBa2Cu3Ox (R=Rare Earth, 6≤x≤7) Compounds: Charge Transfer, Phase Separation, Spin Fluctuations

  • A. Furrer
  • J. Mesot
  • P. Allenspach
  • U. Staub
  • F. Fauth
  • M. Guillaume

Summary

Inelastic neutron scattering has been employed to study the perovskitetype high-T c superconducting compounds RBa2Cu3O x (R = rare earth;6 = x = 7). The variation of the energies and intensities of the observed crystalline-electric-field (CEF) transitions versus the oxygen content x is shown to be predominantly related to a charge transfer process between the chains and the planes. The observed energy spectra are the result of a superposition of two different metallic components and a semiconducting one, i.e., there is clear experimental evidence for phase separation. A two-dimensional bond percolation model explains the appearance of superconductivity as well as the critical oxygen concentrations associated with the two-plateau structure of T c . The line shape of some low-energy R3+ excitations turns out to be highly asymmetric which we interpret in terms of an exchange interaction between the R3+ spins and fluctuating Cu2+ spins. The latter are most likely associated with low-energy spin excitations of spin-polarized polynuclear clusters of Cu2+ ions. From a line-width analysis of the CEF transitions we derive the evolution of the fractal sizes of the clusters versus the oxygen concentration x. Magnetic field-dependent neutron spectroscopic experiments give further evidence for the existence of spin-polarized clusters which are suggested to be the elementary building blocks giving rise to high-temperature superconductivity above the percolation threshold.

Keywords

Anisotropy Eter Perovskite Doyle 

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References

  1. 1.
    L. Soderholm, C.K. Loong, G.L. Goodman, and B.D. Dabrowski, Phys. Rev. B 43, 7923 (1991).ADSCrossRefGoogle Scholar
  2. 2.
    A.T. Boothroyd, S.M. Doyle, D. McK. Paul, and R. Osborn, Phys. Rev. B 45, 10075 (1992).ADSCrossRefGoogle Scholar
  3. 3.
    A.I. Goldman, Y. Gao, S.T. Ting, J.E. Crow, W.H. Li, and J.W. Lynn, J. Magn. Magn. Mater. 76 & 77, 607 (1988).ADSCrossRefGoogle Scholar
  4. 4.
    U. Staub, P. Allenspach, J. Mesot, A. Furrer, R. Müller, T. Schweizer, L.J. Gauckler, H. Blank, and H. Mutka, Z. Phys. B-Condensed Matter 85, 35 (1991).ADSCrossRefGoogle Scholar
  5. 5.
    A. Furrer, P. Brüesch, and P. Unternährer, Phys. Rev. B 38, 4616 (1988).ADSCrossRefGoogle Scholar
  6. 6.
    A. Furrer, P. Allenspach, J. Mesot, U. Staub, H. Blank, H. Mutka, C. Vettier, E. Kaldis, J. Karpinski, S. Rusiecki, and A. Mirmelstein, Eur. J. Solid State Inorg. Chem. 28, 627 (1991).Google Scholar
  7. 7.
    E.A. Goremychkin, R. Osborn, and A.D. Taylor, JETP Lett. 50, 380 (1989).ADSGoogle Scholar
  8. 8.
    U. Staub, F. Fauth, M. Guillaume, J. Mesot, A. Furrer, P. Dosanjh, and H. Zhou, Europhys. Lett. 21, 845 (1993).ADSCrossRefGoogle Scholar
  9. 9.
    A. Furrer, J. Mesot, U. Staub, F. Fauth, and M. Guillaume, to be published in J. Alloys and Compounds.Google Scholar
  10. 10.
    V. Hizhnyakov and E. Sigmund, Physica C 165, 655 (1988).ADSCrossRefGoogle Scholar
  11. 11.
    N.F. Mott, J. Phys.: Condens. Matter 5, 3487 (1993), and references cited therein.ADSCrossRefGoogle Scholar
  12. 12.
    J. Mesot, P. Allenspach, U. Staub, A. Furrer, H. Mutka, R. Osborn, and A. Taylor, Phys. Rev. B 47, 6027 (1993).ADSCrossRefGoogle Scholar
  13. 13.
    M.T. Hutchings, in F. Seitz and D. Turnbull (eds.), Solid State Physics, Vol 16, Academic, New York, 1964, p. 227.Google Scholar
  14. 14.
    R.J. Cava, A.W. Hewat, E.A. Hewat, B. Battlog, M. Marezio, K.M. Rabe, J.J. Krajewski, W.F. Peck Jr., and L.W. Rupp Jr., Physica C 165, 419 (1990).ADSCrossRefGoogle Scholar
  15. 15.
    U. Welp, S. Flescher, W.K. Kwok, J. Downey, Y. Fang, G.W. Crabtree, and J.Z. Liu, Phys. Rev. B 42, 10189 (1990).ADSCrossRefGoogle Scholar
  16. 16.
    P.G. Radaelli, C.U. Segre, D.G. Hinks, and J.D. Jorgensen, Phys. Rev. B 45, 4923 (1992).ADSCrossRefGoogle Scholar
  17. 17.
    J. Mesot, P. Allenspach, U. Staub, A. Furrer, and H. Mutka, Phys. Rev. Lett. 70, 865 (1993).ADSCrossRefGoogle Scholar
  18. 18.
    P. Allenspach, A. Furrer, and B. Rupp, in V.L. Aksenov, N.N. Bogolubov, and N.M. Plakida (eds.), Progress in High-Temperature Superconductivity, Vol. 21, World Scientific, Singapore, 1990, p. 318.Google Scholar
  19. 19.
    V. Hizhnyakov, N. Kristoffel, and E. Sigmund, Physica C 160, 119 (1989).ADSCrossRefGoogle Scholar
  20. 20.
    R.K. Kremer, E. Sigmund, V. Hizhnyakov, F. Hentsch, A. Simon, K.A. Müller, and M. Mehring, Z. Phys. B-Condensed Matter 86, 319 (1992).ADSCrossRefGoogle Scholar
  21. 21.
    S. Kirkpartick, Rev. Mod. Phys. 45, 574 (1973).ADSCrossRefGoogle Scholar
  22. 22.
    B. Rupp, E. Pörschke, P. Meuffels, P. Fischer, and P. Allenspach, Phys. Rev. B 40, 4472 (1989).ADSCrossRefGoogle Scholar
  23. 23.
    G. Wubbeler and O.F. Schirmer, phys. stat. sol. (b) 174, K21 (1992).ADSCrossRefGoogle Scholar
  24. 24.
    I.N. Kurkin, I.Kh. Salikhov, L.L. Sedov, M.A. Teplov, and R.Sh. Zdanov, Zh. Eksp. Teor. Fiz. 103, 1342 (1992) & JETP 76, 657 (1993).Google Scholar
  25. 25.
    P. Wachter and R. Pittini, Proc. ICMAS-93, Superconducting Materials (Paris, December 13–15, 1993), to be published.Google Scholar
  26. 26.
    T. Brückel, H. Capellmann, W. Just, O. Schärpf, S. Kemmler-Sack, R. Kiemel, and W. Schaefer, Europhys. Lett. 4, 1189 (1987).ADSCrossRefGoogle Scholar
  27. 27.
    J. Rossat-Mignod, L.P. Regnault, C. Vettier, P. Bourges, P. Burlet, J. Bossy, J.Y. Henry, and G. Lapertot, Physica C 185–189, 86 (1991).ADSCrossRefGoogle Scholar
  28. 28.
    H.A. Mook, M. Yethiraj, G. Aeppli, T.E. Mason, and T. Armstrong, Phys. Rev. Lett. 70, 3490 (1993).ADSCrossRefGoogle Scholar
  29. 29.
    F. Mezei, B. Faragó, C. Pappas, Gy. Hutiray, L. Rosta, and L. Mihály, Physica C 153–155, 1669 (1988).ADSCrossRefGoogle Scholar
  30. 30.
    A. Furrer and H. Heer, Phys. Rev. Lett. 31, 1350 (1973).ADSCrossRefGoogle Scholar
  31. 31.
    S.W. Lovesey, Theory of neutron scattering from condensed matter, Vol. 2 (Clarendon, Oxford, 1984), p. 6.Google Scholar
  32. 32.
    A. Furrer and H.U. Güdel, Phys. Rev. Lett. 39, 657 (1977).ADSCrossRefGoogle Scholar
  33. 33.
    U. Falk, A. Furrer, H.U. Güdel, and J.K. Kjems, Phys. Rev. Lett. 56, 1956 (1986).ADSCrossRefGoogle Scholar
  34. 34.
    U. Falk, A. Furrer, N. Furer, H.U. Güdel, and J.K. Kjems, Phys. Rev. B 35, 4893 (1987).ADSCrossRefGoogle Scholar
  35. 35.
    M.A. Aebersold, H. Blank, B. Briat, A. Furrer, and H.U. Güdel, Inorg. Chem. 30, 3556 (1991).CrossRefGoogle Scholar
  36. 36.
    E. Sigmund and G.U. Seibold, private communication.Google Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 1994

Authors and Affiliations

  • A. Furrer
    • 1
  • J. Mesot
    • 1
  • P. Allenspach
    • 1
  • U. Staub
    • 1
  • F. Fauth
    • 1
  • M. Guillaume
    • 1
  1. 1.Laboratory for Neutron ScatteringETH Zürich and Paul Scherrer InstitutVilligen PSISwitzerland

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