Modification and nano-patterning of high-Tc superconducting thin films by masked ion beam irradiation

Ion irradiation of the high-temperature superconductor (HTS) YBa2Cu3O7 (Y-123) creates different types of defects depending on ion mass, energy and dose. Irradiation with helium ions of moderate energy (75 keV) primarily creates point defects. We measure in situ the modification of electrical transport properties of Y-123 thin films (thickness 310 nm) during ion irradiation. The He ions penetrate thin films and produce collision cascades with small lateral straggle that allow for patterning of nanostructures in the HTS layer. We present features smaller than 100 nm in size produced by masked ion beam irradiation of Y-123 films. Computer simulations indicate that nano-patterning of Y-123 thin films with 10 nm lateral resolution is achievable.