Subgap conductance features of YBa2Cu3O7-delta edge Josephson junctions

The differential conductance of YBa2Cu3O7-delta edge junctions with a PrBa2 Cu2.9O7-delta barrier has been investigated in detail. One striking propert y of our edge junctions is the existence of a well pronounced, symmetric su bharmonic gap structure which is observed in the differential conductance. These features can be explained by multiple Andreev reflections if we assum e the existence of a second peak in the density of states. Furthermore, a z ero-bias peak in the conductivity was observed in some of the junctions, wh ich may be explained by Andreev bound states at the interface of a d-wave s uperconductor. [S0163-1829(99)08905-5].