c-axis Josephson tunneling in twinned and untwinned YBCO-Pb Junctions

Within a microscopic two-band model of planes and chains with a pairing potential in the planes and off-diagonal pairing between planes and chains we find that the chains make the largest contribution to the Josephson tunneling current and that through them the d-wave part of the gap contributes to the current. This is contrary to the usual assumption that the d-wave part of the gap does not contribute to the c-axis Josephson current for …