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The superconductive weak link properties of microbridges formed in c-axis normal YBa2Cu3O7−δ polycrystalline thin films containing a variable amount of large angle tilt boundaries have been studied. In the low critical current density limit these weak links have current-voltage (I-V) characteristics that are accurately modeled by the resistively shunted junction model. The I-V’s are found to accurately follow a simple scaling law with the product of the critical current and weak link resistance Rn varying linearly with the weak link conductance.

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By patterning-l-pm-wide microbridges in laser ablated YBa,Cu,O, films containing high-angle tilt boundaries, weak links have been isolated with critical currents low enough to avoid self-screening effects. The current-voltage characteristics of these high-angle tilt-boundary weak links are well described by the resistively shunted junction model, if noise rounding is included. The response of the supercurrent to magnetic field and temperature indicates that the weak links are spatially nonuniform, consisting of relatively small areas of high critical current density, J,, separated by areas with very low or zero Jc The response to rf power suggests that the current-phase relation is nonsinusoidal.

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