NORMAL ELECTRON-TUNNELING IN RAMP-TYPE YBA2CU3O7 PRBA2CU3O7/YBA2CU3O7JUNCTIONS PREPARED BY LASER-ABLATION/

Ramp-type YBa2Cu3O7/PrBa2Cu3O7/YBa2Cu3O7 tunneling junctions have been prepared by laser ablation. The voltage dependence of the differentia l conductance is measured at different temperatures and magnetic field s. The junctions are thermally stable and can be cooled down to liquid -helium temperature and warmed up again to room temperature several ti mes without quality loss. At temperatures below 35 K they show clear i ndications of an energy gap and in the same temperature range a very s harp zero-bias anomaly.