| Advances in lithographic techniques make Josephson Junction Arrays (JJAs) promising systems with which to probe many topics in condensed matter physics. Beside the fact that the two dimensional JJA is an interesting system in its own right and represents an excellent physical system to investigate the Berezinski-Kosterlitz-Thouless (BKT) transition, it can be used to study other fundamental topics: dynamical phase transitions, frustration, percolation and charging effects. It can be also used as a simplified model of more complicated systems such as high-T C materials and granular films.; In previous work on JJA's, studies were made on small JJA's that exhibited finite size effects. Also JJA's that were formed by proximity coupling were studied. In the present work we used 1000 x 1000 Josephson Junction arrays fabricated using the Selective Niobium Anodization Process (SNAP) and investigated array characteristics in magnetic fields in both the low and high current limits.; In the limit of low current, the BKT transition was investigated in zero and non-zero magnetic fields. The magnetoresistance was also examined at integer and commensurate values of the array frustration. At high currents array exhibited behavior suggestive of a superconductor-insulator transition tuned by the magnetic field. This transition is discussed in terms of the ratio of the charging energy to the coupling energy. The possibility that this transition could be a quantum phase transition is also considered. |
