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Author Atkinson, W. A. ♦ Carbotte, J. P.
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword PHYSICS ♦ HIGH-TC SUPERCONDUCTORS ♦ PENETRATION DEPTH ♦ COPPER OXIDES ♦ BARIUM OXIDES ♦ YTTRIUM OXIDES ♦ PROXIMITY EFFECT ♦ BCS THEORY ♦ S WAVES ♦ D WAVES ♦ TEMPERATURE DEPENDENCE ♦ FERMI LEVEL ♦ ANISOTROPY ♦ PAIRING INTERACTIONS
Abstract We calculate the penetration depth {lambda} in the {ital a}, {ital b}, and {ital c} directions for a simple model of YBa{sub 2}Cu{sub 3}O{sub 7}. In this model there are two layers---representing a CuO{sub 2} plane and a CuO chain---per unit cell. There is a BCS-like pairing (both {ital s} wave and {ital d} wave are considered) interaction localized in the CuO{sub 2} planes. The CuO chains become superconducting at temperatures lower than {ital T}{sub {ital c}} because of their proximity to the planes, and there is an induced gap in the chains. Since the temperature dependence of the penetration depth in the {ital b} direction (along the chains) is sensitive to the size of the induced gap, the difference between the shapes of the penetration depth curves in the {ital a} and {ital b} directions reveals a great deal about the nature of the condensate in the chains. We find that in our proximity model there are always regions of the chain Fermi surface on which the induced gap is much smaller than {ital T}{sub {ital c}}, so that the temperature dependence of {lambda}{sub {ital b}} is always different than that of {lambda}{sub {ital a}}. Experimental observations of the {ital ab} anisotropy show nearly identical temperature dependences. The main result of our paper, then, is that a simple proximity model in which the pairing interaction is localized to the planes and the planes are coherently coupled to the chains cannot account for the superfluid on the chains.
ISSN 01631829
Educational Use Research
Learning Resource Type Article
Publisher Date 1995-10-01
Publisher Place United States
Journal Physical Review, B: Condensed Matter
Volume Number 52
Issue Number 14


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