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Coupling of phonons to crystal-field excitations in NdBa sub 2 Cu sub 3 O sub 7 minus. delta

Journal Article · · Physical Review Letters; (USA)
; ;  [1]
  1. Max-Planck-Institut fuer Festkoerperforschung, Heisenbergstrasse 1, D-7000 Stuttgart 80, Germany (DE)
We demonstrate the existence of a coupled elementary excitation involving a phonon and a Nd{sup 3+} 4{ital f}-electron crystal-field excitation in the high-{ital T}{sub {ital c}} superconductor NdBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}}. It explains in a natural way the recent observation of a double-peak structure in the Raman spectra as well as in the inelastic neutron scattering spectra near 300 cm{sup {minus}1} at low temperature. Our assignment is supported by measurements of the dependence of this feature on temperature, isotopic substitution, and polarization. A model based on strong coupling of extended phonon states to localized crystal-field excitations describes the observed behavior well.
OSTI ID:
5554365
Journal Information:
Physical Review Letters; (USA), Journal Name: Physical Review Letters; (USA) Vol. 67:1; ISSN PRLTA; ISSN 0031-9007
Country of Publication:
United States
Language:
English