Enhancing the critical current of YBa2Cu3O7 thin films by substrate nanoengineering

The critical current density, J c, can be increased by introducing defects throughout YBa 2Cu 3O 7 superconducting thin films. We propose a new approach of substrate nanoengineering to produce well-controlled defects. LaAlO 3 substrates have been ion-etched with different 34 nm deep patterns prior to the deposition of the films. An annealing step at 1000 °C after substrate etching has been undertaken to negate the Ar-ion damage to the surface. The J c of the so-prepared samples measured at different temperatures has been compared to thin films deposited on plain substrates at the same time. In general, an increase in J c is observed across all temperatures and fields as a result of both patterning and annealing. In particular, at zero field and 85 K, the largest enhancement of > 40% has been recorded for circle and triangle patterns. This new substrate nanoengineering technique is very promising for flux trapping of superconducting devices, particularly because an increase to critical current ( I c) also occurs. Further optimization of depth, size, and shape of the patterns is expected to produce further improvements to J c.