Temperature dependence of the phonon frequencies and linewidths of YBa{sub 2}(Cu{sub 1{minus}x}M{sub x}){sub 4}O{sub 8} for M=Ni and Zn

Journal Article · Thu Jan 01 04:00:00 EST 1998 · Physical Review, B: Condensed Matter

DOI:https://doi.org/10.1103/PhysRevB.57.632· OSTI ID:565901

Watanabe, N; Koshizuka, N ^[1]

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1. Superconductivity Research Laboratory, International Superconductivity Technology Center, 1-10-13 Shinonome, Koto-ku, Tokyo 135 (Japan)

We report on the temperature dependence of Raman spectra for YBa{sub 2}(Cu{sub 1{minus}x}Ni{sub x}){sub 4}O{sub 8} (x=0{endash}0.02) and YBa{sub 2}(Cu{sub 1{minus}x}Zn{sub x}){sub 4}O{sub 8} (x=0{endash}0.01) polycrystals. Below the transition to the superconducting state an anomalous abrupt mode softening and line broadening of the Ba vibrational mode at 100cm{sup {minus}1} are observed in the Raman spectra. The largest shift is observed in the undoped Y1:2:4 samples in which the frequency softens by approximately 5.5cm{sup {minus}1} between T{sub c} and 10 K while the amount of softening is greatly reduced with increasing dopant M concentration. This can be interpreted by considering that under the presence of two gap structure for Y1:2:4 the smaller gap 2{Delta}{sub 1} is near or just above the Ba phonon frequency in undoped samples and its energy decreases with Ni or Zn doping. These phonon anomalies are consistent with the Zeyher-Zwicknagl model assuming the s-wave symmetry of pair function. {copyright} {ital 1998} {ital The American Physical Society}

• OSTI ID: 565901
• Journal Information: Physical Review, B: Condensed Matter, Journal Name: Physical Review, B: Condensed Matter Journal Issue: 1 Vol. 57; ISSN PRBMDO; ISSN 0163-1829
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
BAND THEORY
BARIUM OXIDES
COPPER OXIDES
ENERGY GAP
HIGH-TC SUPERCONDUCTORS
LINE BROADENING
LINE WIDTHS
NICKEL OXIDES
PHONONS
RAMAN SPECTRA
TEMPERATURE DEPENDENCE
VIBRATIONAL STATES
YTTRIUM OXIDES
ZINC OXIDES