Raman-scattering results from Y[sub 1[minus][ital x]]Ca[sub [ital x]]Sr[sub 2]Cu[sub 2]GaO[sub 7]

Journal Article · Sat May 01 00:00:00 EDT 1993 · Physical Review, B: Condensed Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.47.12242· OSTI ID:6891759

Salamon, D; Liu, R; Klein, M V ^[1]; Groenke, D A; Poeppelmeier, K R ^[2]; Dabrowski, B ^[3]; Han, P D; Payne, D A ^[4]

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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 Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208 (United States)
3. Department of Physics, Faraday Hall, Northern Illinois University, DeKalb, Illinois 60115 (United States) Materials Science Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439 (United States)
4. 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)

We present a Raman-scattering study of Y[sub 1[minus][ital x]]Ca[sub [ital x]]Sr[sub 2]Cu[sub 2]GaO[sub 7] for both the [ital x]=0 parent compound and doped compositions with [ital x]=0.25 and [ital x]=0.40. Extrapolation from YBa[sub 2]Cu[sub 3]O[sub 7[minus][ital d]] and other cuprates allows us to assign many of the Raman-active phonon modes in the [ital x]=0 material, as well as identify a two-magnon scattering peak, a second-order phonon scattering peak, and a Raman continuum out to 4000 cm[sup [minus]1]. Despite compositional inhomogeneities, the doped superconducting samples show some of the same low-energy phonon features as the [ital x]=0 material. There is, however, a doping-dependent shift in the positions of features in the 500--700 cm[sup [minus]1] range, possibly due to Ca locating on Sr sites instead of Y sites. The relative intensities of the phonon peaks in the doped material are also changed from the insulator ([ital x]=0), suggesting that a resonant Raman phenomenon is occurring. The temperature-dependent spectra show what appears to be a superconducting dip in the background intensity, but the low superconducting fractions in these samples make this difficult to verify. The doped material also has a Raman continuum out to 4000 cm[sup [minus]1] just as in the [ital x]=0 samples, but with the two-magnon and second-order phonon scattering peaks significantly reduced in intensity. This may be a result of changes in the long-range ordering, or another manifestation of the same resonance phenomena occurring at lower energies. Single-crystal samples of the doped material Y[sub 1[minus][ital x]]Ca[sub [ital x]]Sr[sub 2]Cu[sub 2]GaO[sub 7] are necessary for a more conclusive Raman study.

• DOE Contract Number: W-31-109-ENG-38
• OSTI ID: 6891759
• Journal Information: Physical Review, B: Condensed Matter; (United States), Vol. 47:18; ISSN 0163-1829
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CALCIUM OXIDES
RAMAN SPECTRA
COPPER OXIDES
GALLIUM OXIDES
STRONTIUM OXIDES
YTTRIUM OXIDES
HIGH-TC SUPERCONDUCTORS
MAGNONS
PHONONS
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE 0000-0013 K
ALKALINE EARTH METAL COMPOUNDS
CALCIUM COMPOUNDS
CHALCOGENIDES
COPPER COMPOUNDS
GALLIUM COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
QUASI PARTICLES
SPECTRA
STRONTIUM COMPOUNDS
SUPERCONDUCTORS
TEMPERATURE RANGE
TRANSITION ELEMENT COMPOUNDS
YTTRIUM COMPOUNDS
360204* - Ceramics
Cermets
& Refractories- Physical Properties