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Title: Raman scattering from A sub g and B sub 1 g phonons in Bi sub 2 Sr sub 2 Ca sub n minus 1 Cu sub n O sub 2 n +4 ( n =1,2)

Journal Article · · Physical Review, B: Condensed Matter; (United States)
;  [1]; ;  [2]
  1. Department of Physics and Materials Research Laboratory, University of Illinois at Urbana-Champaign, 1110 West Green Street, Urbana, Illinois 61801 (United States)
  2. Department of Materials Science and Engineering and Materials Research Laboratory, University of Illinois at Urbana-Champaign, 104 South Goodwin Avenue, Urbana, Illinois 61801 (United States)

Raman measurements were performed on intergrowth-free Bi{sub 2}Sr{sub 2}CuO{sub 6+{delta}} (2:2:0:1) and Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+{delta}} (2:2:1:2) crystals. The phonon spectra of both phases are similar; however, two lowest-frequency phonon lines corresponding to the 28- and 47-cm{sup {minus}1} lines in 2:2:1:2 were observed at 20 and 41 cm{sup {minus}1} in 2:2:0:1, and, in both cases, these two Raman features appear exclusively in the {ital z}({ital yy}){ital {bar z}} configuration. In addition, two weak {ital A}{sub {ital g}} lines at 109 and 129 cm{sup {minus}1}, which are absent in spectra of 2:2:0:1, were resolved for 2:2:1:2. An overall assignment can be achieved by attributing the two lowest-frequency lines to the first- and second-order scattering features of the amplitude mode of the superstructural modulation, and the other lines to the optical-phonon modes of the distorted orthorhombic subcell. A careful comparison between the spectra of the single- and double-CuO{sub 2}-layer Bi compounds enables us to clarify some controversies on assigments of certain phonon modes, especially those in the CuO{sub 2} layer.

OSTI ID:
7043247
Journal Information:
Physical Review, B: Condensed Matter; (United States), Vol. 45:13; ISSN 0163-1829
Country of Publication:
United States
Language:
English