Relaxation effects in the transition temperature of superconducting HgBa{sub 2}CuO{sub 4+{delta}}
- Department of Physics, Washington University, C.B. 1105, One Brookings Drive, St. Louis, Missouri 63130 (United States)
- Department of Physics, University of North Dakota, P.O. Box 7129, Grand Forks, North Dakota 58202-7129 (United States)
- Materials Science Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439 (United States)
In previous studies on a number of underdoped and overdoped high-temperature superconductors, including YBa{sub 2}Cu{sub 3}O{sub 7{minus}y} and Tl{sub 2}Ba{sub 2}CuO{sub 6+{delta}}, the transition temperature T{sub c} has been found to change with time in a manner which depends on the sample{close_quote}s detailed temperature and pressure history. This relaxation behavior in T{sub c} is believed to originate from rearrangements within the oxygen sublattice. In the present high-pressure studies on HgBa{sub 2}CuO{sub 4+{delta}} to 0.8 GPa we find clear evidence for weak relaxation effects in strongly underdoped and overdoped samples (T{sub c}{approx_equal}40{endash}50thinspK) with an activation energy E{sub A}(1thinspbar){approx_equal}0.8{endash}0.9thinspeV. For overdoped HgBa{sub 2}CuO{sub 4+{delta}} &hthinsp;E{sub A} increases under pressure more rapidly than previously observed for YBa{sub 2}Cu{sub 3}O{sub 6.41}, yielding an activation volume of +11{plus_minus}5thinspcm{sup 3}; the dependence of T{sub c} on pressure is markedly nonlinear, an anomalous result for high-T{sub c} superconductors in the present pressure range, giving evidence for a change in the electronic and/or structural properties near 0.4 GPa. {copyright} {ital 1999} {ital The American Physical Society}
- Research Organization:
- Argonne National Laboratory (ANL), Argonne, IL
- OSTI ID:
- 692512
- Journal Information:
- Physical Review, B: Condensed Matter, Journal Name: Physical Review, B: Condensed Matter Journal Issue: 13 Vol. 60; ISSN PRBMDO; ISSN 0163-1829
- Country of Publication:
- United States
- Language:
- English
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