Point—contact spectroscopy on BSCCO— and YBCO—break—junctions

Abstract We are investigating in point-contact spectroscopy on YBa 2 Cu 3 O 7−δ - and Bi 2 Sr 2 Ca 2 Cu 3 O 10+δ -single crystals and granular samples by break-junction technique [1]. Such contacts show a transition from single electron tunneling to Josephson-effect dominated junctions. In between exists the regime of metal-like contacts where the resistivity is mainly given by a normal- or semiconducting interlayer region. Here our main investigations take place. We will show current-voltage characteristics (CVC) and their derivatives, with features explainable by Andreev-multiple reflection (AR) [2]. The temperature, magnetic field and high-frequency dependencies are investigated. Additionally we compare our results with those we received for conventional SSmS (Sm = semiconductor) sandwich junctions [3].