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Angular position of nodes in the superconducting gap of YBCO

H. Aubin·K. Behnia·M. Ribault·R. Gagnon·L. Taillefer
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Abstract

The thermal conductivity of a YBCO single crystal has been studied as a function of the relative orientation of the crystal axes and a magnetic field rotating in the Cu-O planes. Measurements were carried out at several temperatures below T_c and at a fixed field of 30 kOe. A four-fold symmetry characteristic of a superconducting gap with nodes at odd multiples of 45 degrees in k-space was resolved. Experiments were performed to exclude a possible macroscopic origin for such a four-fold symmetry such as sample shape or anisotropic pinning. Our results impose an upper limit of 10% on the weight of the s-wave component of the essentially d-wave superconducting order parameter of YBCO.

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H. Aubin, K. Behnia, M. Ribault, R. Gagnon, L. Taillefer. 1996-11-08. Angular position of nodes in the superconducting gap of YBCO. https://doi.org/10.1103/physrevlett.78.2624

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