SUPERCONDUCTING OXIDE MULTILAYERS AND SUPERLATTICES - PHYSICS, CHEMISTRY, AND NANOENGINEERING

A technique has been developed for synthesis of heterostructures conta ining various Bi- and Dy-based cuprates and other complex oxides, with a high level of control of deposition of individual atomic monolayers as well as capability for atomic-layer engineering. It produces multi layers and superlattices which display striking long-range crystalline order and atomically abrupt interfaces; this enables deposition of on e-unit-cell thick 2212 layers which display HTSC, and of barriers less than 1 nm thick with no pinholes over macroscopic areas. Employing Dy -doped 1278 barriers, trilayer Josephson junctions with I(c)R(n) = 5-7 mV have been fabricated. Phase locking is seen in stacked junctions. Tunneling transport (but no supercurrent) is observed in junctions wit h insulating titanate barriers. Modulation doping is attained by omitt ing or inserting entire monolayers, and artificial metastable high-T-c compounds have been synthesized in this way. Finally, long-range prox imity effects are seen in 2212-2201-2212 trilayers.