Intralayer-versus-interlayer pairing in the copper oxide superconductors
- Materials Science Division, Argonne National Laboratory, Argonne, Illinois (USA) Solid State Division, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, Tennessee (USA)
- Solid State Division, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, Tennessee (USA)
We have investigated the competing roles of intralayer {ital s}-wave and interlayer BCS-like pairing in determining the {ital c}-axis versus {ital ab}-plane energy-gap anisotropy in layered superconductors with {ital N}=1,2 conducting planes per unit-cell edge {ital s}. For {ital N}=1, intralayer {ital s}-wave pairing leads to a conventional order parameter (OP) {Delta}{sub 0} with a transition temperature ({ital T}{sub {ital c}}) value {ital T}{sub {ital c}0} and isotropic energy gap 2{vert bar}{Delta}{sub 0}{vert bar}. For interlayer pairing, the four-vector gap function {tilde {Delta}}{sub 3}({ital k}{sub {ital z}}) contains a singlet OP {Delta}{sub {ital s}} and a vector triplet OP {Delta}{sub {ital t}}, with corresponding normalized gap functions {radical}2 cos{ital k}{sub {ital z}s} and {radical}2 sin{ital k}{sub {ital z}s}. Since {Delta}{sub {ital s}} and {Delta}{sub {ital t}} have identical {ital T}{sub {ital c}} values ({ital T}{sub {ital c}{ital s}}={ital T}{sub {ital c}{ital t}}), the free energy is minimized when {vert bar}{Delta}{sub {ital s}}{vert bar}={vert bar}{Delta}{sub {ital t}}{vert bar}, and the resulting gap 2{vert bar}{Delta}{vert bar} is found to be {ital isotropic}. However, 2{vert bar}{Delta}{vert bar} is completely {ital incompatible} with 2{vert bar}{Delta}{sub 0}{vert bar}. For {ital N}=2, there are two intralayer pairing OP's {Delta}{sub 0} and {Delta}{sub 1}, and two interlayer four-vector gap functions {tilde {Delta}}{sub 3}({ital k}{sub {ital z}}) and {tilde {Delta}}{sub 2}({ital k}{sub {ital z}}), all of which could contribute to measurable quantities in the Gaussian-fluctuation regime above the highest {ital T}{sub {ital c}} value.
- Research Organization:
- Argonne National Laboratory (ANL), Argonne, IL
- DOE Contract Number:
- AC05-84OR21400; W-31109-ENG-38; W-7405-ENG-82
- OSTI ID:
- 5127044
- Journal Information:
- Physical Review, B: Condensed Matter; (United States), Vol. 44:14; ISSN 0163-1829
- Country of Publication:
- United States
- Language:
- English
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