Phase separation and oxygen diffusion in electrochemically oxidized La{sub 2}CuO{sub 4+{delta}}: A static magnetic susceptibility study
- Center for Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)
- Ames Laboratory and Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011 (United States)
The compound La{sub 2}CuO{sub 4+{delta}} is known to phase separate for 0.01{approx_lt}{delta}{approx_lt}0.06 below a temperature {ital T}{sub ps}{approximately}300 K into the nearly stoichiometric antiferromagnetic compound La{sub 2}CuO{sub 4.01{endash}4.02} with N{acute e}el temperature {ital T}{sub {ital N}}{approximately}250 K, and a metallic oxygen-rich phase La{sub 2}CuO{sub {approx_equal}4.06} with superconducting transition temperature {ital T}{sub {ital c}}{approx_equal}34 K. We report studies of the superconducting and normal-state static magnetic susceptibility {chi} of La{sub 2}CuO{sub 4+{delta}} samples with 0{approx_lt}{delta}{le}0.11 prepared by electrochemical oxidation or reduction of conventionally synthesized ceramic La{sub 2}CuO{sub 4+{delta}}. The upper limit to the miscibility gap at low {ital T} is found be {delta}{approx_lt}0.065, in agreement with the previous work. The interstitial oxygen diffusion during the phase-separation process was studied using thermal- and magnetic-field history-dependent {chi}({ital T},{ital t}) measurements versus temperature {ital T} and time {ital t} as a probe. Phase separation is found to be suppressed by quenching at {approx_gt}100 K/s and favored by slow cooling at {approximately}0.5 K/min. A large thermal hysteresis of both the normal and superconducting state {chi}({ital T}) was observed between data obtained after quenching to 5 K and then warming, and data obtained while or after slowly cooling from 300 K, for samples of La{sub 2}CuO{sub 4+{delta}} ({delta}{approx_equal}0.030, 0.044) within the miscibility gap. Quenching reduces {ital T}{sub {ital c}} by {approx_equal}5 K relative to the value (34 K) obtained after slow cooling. A similar decrease is found for La{sub 2}CuO{sub 4.065} which does not phase separate, indicating the importance of oxygen-ordering effects within this single phase. (Abstract Truncated)
- Research Organization:
- Ames National Laboratory
- DOE Contract Number:
- W-7405-ENG-82
- OSTI ID:
- 285631
- Journal Information:
- Physical Review, B: Condensed Matter, Journal Name: Physical Review, B: Condensed Matter Journal Issue: 1 Vol. 54; ISSN 0163-1829; ISSN PRBMDO
- Country of Publication:
- United States
- Language:
- English
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