Periodic and aperiodic superconducting microstructures

We summarize some recent activities of our group involving e-beam and optically patterned, Nb-based, superconducting nanostructures, as well as related computer modeling studies. The devices described are: i) Fiske cavities buried in a Nb base layer and driven by an overlying Nb/AlOX/Nb Josephson oscillator junction, ii) Nb/AlOX/Al/AlOX/Nb (SINIS) five-layer double junctions which Maezava and Shoji have observed to perform as nonhysteretic SNS Josephson single junctions, and iii) critical current measurements on e-beam patterned, two-dimensional arrays of periodic and aperiodic ferromagnetic Ni "dots" embedded in a Nb film. We also describe a method of "base-electrode planerization" leading to more uniform junction formation. The computer modeling studies involve the stable and unstable solution states in a static magnetic field of current-biased single and double Josephson junctions.