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Experimental determination of the superconducting pairing state in YBCO from the phase coherence of YBCO-Pb dc SQUIDs

D. A. Wollman, D. J. Van Harlingen, W. C. Lee, D. M. Ginsberg, A. J. Leggett

DOI 10.1103/PhysRevLett.71.2134 · Physical Review Letters

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Abstract

We present an experiment designed to determine directly the symmetry of the pairing state in the cuprate superconductors. From the magnetic flux modulation of YBCO-Pb dc SQUIDs, we determine the spatial anisotropy of the phase of the order parameter in single crystals of YBCO. The experimental results are complicated by SQUID asymmetries and the trapping of magnetic vortices, but taken as a whole give rather strong evidence for a phase shift of π that is predicted for the dx2−y2 pairing state. This is further corroborated by single junction modulation measurements.

Source-reported materials — not catalogue approval

FormulaReported Tc (K)Pressure (GPa)Type
YBa2Cu3O7-δ

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—Pressure not reportedunknown
Bi2Sr2CaCu2O8

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Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.

—Pressure not reportedunknown
YBa2Cu3O6.8

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—Pressure not reportedunknown
Pb

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—Pressure not reportedunknown

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