Structural Changes in YBa₂Cu₃O₇ Thin Films Modified with He⁺-Focused Ion Beam for High-Temperature Superconductive Nanoelectronics

Abstract

Irradiation of high-temperature superconductor YBa 2 Cu 3 O 7 (YBCO) with high-energy He + ions is known to cause structural changes in the YBCO film, decreasing the critical temperature T C and finally leading to a superconductor-toinsulator transition. This allows one to pattern narrow insulating regions with a focused ion beam (FIB) and thus fabricate nanoscale Josephson junctions on YBCO films. Moreover, such ion irradiation is known to cause structural changes in the YBCO film. However, details of how these structural changes occur in nanoscale devices produced by FIB remain unknown. Using nanofocus X-ray diffraction, we study the changes in the YBCO crystal lattice and investigate how the nature of these changes depends on the size of the irradiated regions. These data provide an important understanding of how oxide superconductors can be tailored at the nanometer scale for various applications.

Temporal Evolution of Defects and Related Electric Properties in He-Irradiated YBa2Cu3O7−δ Thin Films

“…Nanopatterning of YBCO thin films by focused-ion-beam irradiation has proven to be a versatile method for fabricating ultradense vortex pinning landscapes and Josephson junctions. However, one might have concerns about their long-term stability due to oxygen migration that could blur the oxygen-defect profile [43]. Building on our previously presented experiments, we investigate the temporal evolution of the critical temperature, the resistivity, and the critical current of an 80 nm thick YBCO film on MgO substrate that was irradiated with a 30 keV He + focused ion beam in the HIM at room temperature.…”