Planar thin film YBa2Cu3O7−δ Josephson junctions via nanolithography and ion damage

Abstract

We have developed a process to fabricate planar high-Tc Josephson junctions using nanolithography and a 200 keV ion implanter. Conduction occurs in the ab plane and is interface free. We can systematically tune devices to operate at temperatures between 1 K and the Tc of the undamaged superconducting material by varying the length of the weak link and by changing the amount of ion damage. All of the devices showed clear dc and ac Josephson effects. Measurement of R(T) and Ic(T) of the weak links revealed trends which were consistent with a proximity effect.