Angle-resolved phase-sensitive determination of the in-plane gap symmetry in YBa2Cu3O7-δ

J.R. Kirtley, C.C. Tsuei, Ariando, C.J.M. Verwijs, S. Harkema, H. Hilgenkamp

Research output: Contribution to journalArticleAcademicpeer-review

112 Citations (Scopus)


Understanding the nature of the ground state and its low-lying excitations in the copper oxide superconductors is a prerequisite for determining the origin of high-temperature superconductivity. A superconducting order parameter (that is, the energy gap) with a predominantly dx2-y2 symmetry is well-established. However, various deviations from a pure d-wave pair state, such as the possibility of Cooper pairing with broken time-reversal symmetry or an admixed dx2-y2+s pair state, have been theoretically predicted and actively sought in numerous experimental studies. Here, we present an angle-resolved phase-sensitive technique for accurately determining the in-plane pairing symmetry, and demonstrate this technique in optimally doped YBa2Cu3O7-δ. We find that the gap along the b-axis (Cu–O chain) direction is at least 20% larger than that along the a-axis direction, and that any imaginary idxy, is or ip component must be smaller than a few per cent of the dx2-y2 component of the gap.
Original languageEnglish
Pages (from-to)190-194
Number of pages5
JournalNature physics
Publication statusPublished - 2006


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