Nanobridges of optimized YBa2Cu3O7 thin films for superconducting flux-flow type devices

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Abstract
Superconducting nanobridges of YBa2Cu3O7 thin films with widths down to w=200 nm and lengths from 0.2 to 10 μm are patterned using metal masks fabricated by electron‐beam lithography and reactive ion etching. The YBa2Cu3O7 films were dry etched by ion beam milling at minimal energies of 250 eV on a liquid‐nitrogen‐cooled sample holder. Long bridges (l=10 μm) showed superconducting features similar to those of unstructured YBa2Cu3O7 films. Short nanobridges exhibited phase‐slip center behavior up to the transition temperature of 87–89 K. Shapiro steps were observed in the current‐voltage characteristics in applied microwave fields and the critical current decreased linearly with the amplitude of the microwave field.