Experimental observation of the selection rule in Josephson coupling between and
Department of Physics, The Pennsylvania State
University University Park, PA 16802, USA
2 Department of Physics, Kyoto University - Kyoto 606-8502, Japan and CREST, Japan Science and Technology Corporation Kawaguchi, Saitama 332-0012, Japan
Accepted: 24 May 2000
We have carried out experimental studies on the Josephson coupling between a conventional s-wave superconductor (In) and and found that the coupling is allowed in the in-plane direction, but not along the c-axis. This selection rule indicates that the symmetry of superconducting order parameter of is either p- or, alternatively, purely d-wave. If is a p-wave superconductor, as strongly favored by other experimental evidence, our result suggests that the pairing state of is , with , a nodeless state in which the spins of the superconducting electrons lie in the planes.
PACS: 74.50.+r – Proximity effects, weak links, tunneling phenomena, and Josephson effects / 74.25.Fy – Transport properties (electric and thermal conductivity, thermoelectric effects, etc.) / 74.70.-b – Superconducting materials(excluding high- compounds)
© EDP Sciences, 2000