High-frequency Raman scattering in the superconducting and semiconducting phases of Ba/sub 2/YCu/sub 3/O/sub x/-type single crystals and ceramics

Journal Article · Thu Dec 01 04:00:00 EST 1988 · Phys. Rev. B: Condens. Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.38.11346· OSTI ID:6889736

Krol, D M; Stavola, M; Schneemeyer, L F; Waszczak, J V; O'Bryan, H; Sunshine, S A

We report the high-frequency Raman spectra (..delta omega..>1000 cm/sup -1/) of Ba/sub 2/YCu/sub 3/O/sub x/ and various analogs, measured at room temperature. In semiconducting single crystals and ceramics of Ba/sub 2/YCu/sub 3/O/sub x/ (xapprox. =6) and semiconducting single crystals of Sr/sub 2/YCu/sub 2.4/Al/sub 0.6/O/sub x/ we find a peak at 1220 cm/sup -1/ (A/sub 1//sub g/ symmetry) and a broadband at 2600 cm/sup -1/ (B/sub g/). The 1220-cm/sup -1/ peak can be interpreted as scattering from excitations of single spins near defects or two-phonon scattering. The 2600-cm/sup -1/ band is attributed to scattering from spin-pair excitations. In the spectra of superconducting Ba/sub 2/YCu/sub 3/O/sub x/ crystals and ceramics (xapprox. =7) these bands are not present. In all samples, semiconductors and superconductors, we observe flat and featureless spectral intensity (A/sub 1//sub g/ symmetry) extending up to ..delta omega.. = 5000 cm/sup -1/, the origin of which is not understood at present. The similarity between the high-frequency spectra of Ba/sub 2/YCu/sub 3/O/sub x/ (xapprox.6) and Sr/sub 2/YCu/sub 2.4/Al/sub 0.6/O/sub x/ (Al on Cu(1)-chain sites) shows that the magnetic scattering is determined by the structure of the Cu(2)-O planes and is not affected by the distance between the planes or by the Cu(1)-chain structure.

• Research Organization: ATandT Bell Laboratories, Murray Hill, New Jersey 07974
• OSTI ID: 6889736
• Journal Information: Phys. Rev. B: Condens. Matter; (United States), Journal Name: Phys. Rev. B: Condens. Matter; (United States) Vol. 38:16; ISSN PRBMD
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360204* -- Ceramics
Cermets
& Refractories-- Physical Properties
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BARIUM COMPOUNDS
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COPPER OXIDES
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