Critical current enhancements in YBa_2Cu_3O_(7-x) films incorporating nanoparticulate Y_2O_3 Artificial Pinning Centers

摘要

For wide applications of YBa_2Cu_3O_x (YBCO) high temperature superconductors to electric devices high critical current density (J_c) under magnetic fields are required. Many researchers used to induce artificial pinning centers (APCs) in YBCO films for enhancement of their J_c in a wide range of temperatures. A common way to induce APCs in YBCO films is to ablate a target comprising a mixture of YBCO and nanoparticles of non-superconducting phase, yielding a YBCO thin film incorporating non-superconducting nanorods, acting as 1D-APC. We used a surface-modified YBCO target: a thin Y_2O_3 sector, cut from Y_2O_3 substrate, was set on the YBCO target, and thin films were ablated by PLD on SrTiO_3 buffered-MgO single crystals. We obtained high quality YBCO films incorporating nanoparticulate Y_2O_3 (3D-APCs). The performance of the Y_2O_3 doped film in a field becomes remarkably high, especially at temperatures lower than 77 K).