Enhancing the critical current of YBa2Cu3O7 thin films by substrate nanoengineering

Abstract

The critical current density, Jc, can be increased by introducing defects throughout YBa2Cu3O7 superconducting thin films. We propose a new approach of substrate nanoengineering to produce well-controlled defects. LaAlO3 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 Jc 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 Jc 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 (Ic) also occurs. Further optimization of depth, size, and shape of the patterns is expected to produce further improvements to Jc.