Rare-earth ion size effect on resistivity, susceptibility, and superconductivity of {ital R}Ba{sub 2}Cu{sub 3{minus}{ital x}}Zn{sub {ital x}}O{sub 7{minus}{ital y}} ({ital R}= Yb, Er, Y, Dy, Gd, Eu, Sm, and Nd)
- Institut fuer Schicht- und Ionentechnik, Forschungszentrum Juelich Gesellschaft mit beschraenkter Haftung, Postfach 1913, D-52425 Juelich (Germany)
A systematic study of Zn doping on the resistivity {rho}, dc susceptibility {chi}, and superconducting {ital T}{sub {ital c}} of {ital R}Ba{sub 2}Cu{sub 3{minus}{ital x}}Zn{sub {ital x}}O{sub 7{minus}{ital y}} systems ({ital R}=Yb, Er Y, Dy, Gd, Eu, Sm, and Nd, and 0{le}{ital x}{le}0.3) is reported. X-ray powder diffraction (XRD) shows that all samples consist essentially of a single phase and retain the orthorhombic structure in the range of 0{le}{ital x}{le}0.3 (except for {ital R}=Yb in the range of 0{le}{ital x}{le}0.15). By analyzing our Raman spectra and XRD data, Zn atoms are found more likely to substitute on Cu(2) sites. Doping with Zn on the Cu site in these systems causes a rapid nearly linear decrease of {ital T}{sub {ital c}} as Zn content increases. The reduction of {ital T}{sub {ital c}} for {ital R}Ba{sub 2}Cu{sub 3{minus}{ital x}}Zn{sub {ital x}}O{sub 7{minus}{ital y}} is found to depend strongly on the ionic radius of the rare-earth element {ital R}. This effect resembles the ion size effect on {ital T}{sub {ital c}} in {ital R}{sub 1{minus}{ital x}}Pr{sub {ital x}}Ba{sub 2}Cu{sub 3}O{sub 7{minus}{ital y}}, where Pr substitutes on the {ital R} site, and in {ital R}Ba{sub 2}Cu{sub 3{minus}{ital x}}Ga{sub {ital x}}O{sub 7{minus}{ital y}}, where Ga substitutes on the Cu(1) sites in Cu-O chains, although in the {ital R}Ba{sub 2}Cu{sub 3{minus}{ital x}}Zn{sub {ital x}}O{sub 7{minus}{ital y}} systems Zn is found to be more likely to substitute on the Cu(2) sites in Cu-O{sub 2} planes. The suppression of superconductivity by zinc and the rare-earth ion size effect on {ital T}{sub {ital c}} in these systems is interpreted in terms of a Mott spin bipolaron model. {copyright} {ital 1996 The American Physical Society.}
- OSTI ID:
- 284706
- Journal Information:
- Physical Review, B: Condensed Matter, Journal Name: Physical Review, B: Condensed Matter Journal Issue: 22 Vol. 53; ISSN PRBMDO; ISSN 0163-1829
- Country of Publication:
- United States
- Language:
- English
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