ALL-YBA2CU3O7 TRILAYER TUNNEL-JUNCTIONS WITH SR2ALTAO6 BARRIER

A new barrier material, Sr2AlTaO6, was employed in fabricating all-YBa 2Cu3O7 trilayer tunnel junctions using in situ coevaporation and sputt ering deposition. It was found that the superior material properties o f Sr2AlTaO6 allow the use of a very thin barrier layer. A dramatic inc rease in the quasiparticle density of states at the YBa2Cu3O7 supercon ductive gap was observed for the first time from thin-film all-YBa2Cu3 O7 devices. Well-defined gap structures were observed at temperatures up to 47 K. The tunneling characteristics are consistent with the typi cal superconductor-insulator-superconductor behavior. The temperature dependence of the superconductive gap is compared with the BCS theory. (C) 1994 American Institute of Physics.