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Magnetic measurements of the upper and lower critical fields of oxygen-deficient YBa sub 2 Cu sub 3 O sub 7 minus. delta. single crystals

Journal Article · · Physical Review, B: Condensed Matter; (USA)
; ; ; ; ; ; ; ; ;  [1];  [2]
  1. Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (USA)
  2. Department of Physics, University of California-Davis, Davis, California 95616 (USA)

We present dc-magnetization measurements in fields up to 5 T on oxygen-deficient ({ital T}{sub {ital c}}{congruent}60 K) YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} single crystals. The upper-critical-field slopes are {minus}2.0 and {minus}8.7 T/K and the lower critical fields at 5 K are 83 and 25 Oe for fields perpendicular and parallel to the Cu-O planes, respectively. The upper-critical-field slope anisotropy is not substantially different from the anisot- ropy found for the 90-K crystals. The {ital H}{sub {ital c}1} values are, however, much smaller for the 60-K crystals. We explain these results through a model in which the chains do not contribute significantly to the coupling between the Cu-O planes but rather serve as a charge reservoir for the superconductivity that occurs in the planes.

Research Organization:
Argonne National Laboratory (ANL), Argonne, IL
DOE Contract Number:
W-31109-ENG-38
OSTI ID:
5561958
Journal Information:
Physical Review, B: Condensed Matter; (USA), Journal Name: Physical Review, B: Condensed Matter; (USA) Vol. 43:16; ISSN PRBMD; ISSN 0163-1829
Country of Publication:
United States
Language:
English