The flux pinning effect of different doping element combinations on metal-organic deposition-derived YBa2Cu3O7−δ nanocomposite films

Elemental doping has been proven effective in improving the flux pinning of yttrium barium copper oxide (YBa₂Cu₃O_7−δ, YBCO) nanocomposite thin films. In the present work, we increased the number of doping elements to five to investigate the flux pinning effect of YBCO. The Zr-doped, Zr, Hf and Sn co-doped, Zr, Hf, Sn and Ta co-doped, and Zr, Hf, Sn, Ta and Mn co-doped YBCO films deposited on LaMnO₃/MgO/Y₂O₃/Al₂O₃/ Hastelloy substrate were systematically studied. The samples were prepared by low-fluorine metal-organic deposition method, with a total dopant of 8 mol%. All films exhibit good c-axis growth and the multi-doping helps refining the surface particles, resulting in a smoother surface. The in-field properties of the films increase with the increase of co-doped element numbers, especially at a low temperature of 30 K. The pinning force density (F_p) and critical current density (J_c) are significantly improved by five-element Zr, Hf, Sn, Ta and Mn co-doped, which is about 3 times and 1.6 times higher, respectively, than that of the undoped film at 30 K and 1 T.