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Superconducting-plasma resonance along the {ital c} axis in various copper oxide superconductors

Journal Article · · Physical Review, B: Condensed Matter
;  [1]
  1. Nippon Telegraph and Telephone Corporation, Basic Research Laboratories, 3-1 Morinosato Wakamiya, Atsugi-shi, Kanagawa 243-01 (Japan)

Superconducting plasma along the {ital c} axis in the far-infrared region are observed in various high-{ital T{sub c}} cuprates including electron-doped and Bi cuprates. It is shown that the sphere resonance of the powder samples occurs near the frequency where the plasma along the {ital c} axis exists, since it is only sensitive to the {ital c}-axis dielectric constant in the far-infrared region due to the metal-like property in the {ital ab} plane. This method provides an alternative to the reflectivity measurement of single crystals for investigating the plasma along the {ital c} axis. By measuring down to 7.5 cm{sup {minus}1}, the resonance is observed in Bi{sub 1.85}Pb{sub 0.35}Sr{sub 2}Ca{sub 2}Cu{sub 3.1}O{sub {ital y}}, La{sub 1.82}Ca{sub 1.18}Cu{sub 2}O{sub 6+{delta}}, (Nd{sub 0.66}Sr{sub 0.205}Ce{sub 0.135}){sub 2}CuO{sub 4} ({ital T}{sup *} phase), (Ba{sub 0.56}Sr{sub 0.44}){sub 2}Cu{sub 1.1}O{sub 2.2+{delta}}(CO{sub 3}){sub 0.9}, Pr{sub 1.85}Ce{sub 0.15}CuO{sub 4}, and Nd{sub 2}CuO{sub 4-{ital x}}F{sub {ital x}}. Among the Bi cuprates, however, no resonance is observed in Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub {ital y}} and Bi{sub 2}Sr{sub 1.6}La{sub 0.4}CuO{sub {ital y}} in this frequency region, which suggests that the resonance exists below 7.5 cm{sup -1}. The resonance frequencies are discussed based on the Josephson-coupled layer model, and the {ital c}-axis penetration depth {lambda}{sub {ital c}} are estimated from the resonance frequencies. It appears that {lambda}{sub {ital c}} depends on the insulating nature of the barrier layer between CuO{sub 2} planes. Substitution effects on the resonance are also investigated in La{sub 2-{ital x}}Sr{sub {ital x}}(Cu{sub 1-{ital z}}Zn{sub {ital z}})O{sub 4}, Nd{sub 1.85}Ce{sub 0.15}(Cu{sub 1-{ital z}}Zn{sub {ital z}})O{sub 4}, and YBa{sub 2}(Cu{sub 1-{ital z}}Co{sub {ital z}}){sub 3}O{sub 6+{delta}}, and compared to the results of YBa{sub 2}(Cu{sub 1-{ital z}}Zn{sub {ital z}}){sub 3}O{sub 6+{delta}}.

OSTI ID:
390345
Journal Information:
Physical Review, B: Condensed Matter, Journal Name: Physical Review, B: Condensed Matter Journal Issue: 10 Vol. 54; ISSN PRBMDO; ISSN 0163-1829
Country of Publication:
United States
Language:
English