Tailoring the vortex pinning strength of YBCO thin films by systematic incorporation of hybrid artificial pinning centers

The effect of hybrid (columnar and spherical together) artificial pinning centers (APCs) on the vortex pinning properties of YBa₂Cu₃O_7-δ(YBCO) thin films is investigated in detail on the basis of variation of critical current density (J_C) with applied magnetic field and also with the orientation of the applied magnetic field at 65 K and 77 K. Premixed YBCO + BaSnO₃ composite targets are used for the deposition of the YBCO films which consist of self-assembled BaSnO₃ nanocolumns (1D APCs); on the other hand, for the deposition of the YBCO films with hybrid APCs (BaSnO₃ nanocolumns together with Y₂O₃ nanoparticles), the surface of the premixed YBCO + BaSnO₃ composite targets are modified by putting a thin Y₂O₃ sectored piece on the premixed YBCO + BaSnO₃ composite targets by means of silver paste. F _pmax value increases systematically with incorporation of 1D and 1D and 3D APCs and it also shifts towards higher applied magnetic fields. Films with 1D APCs exhibit a strong J _C peak at Θ = 0� (H//c-axis) whereas films consisting of hybrid APCs exhibit enhanced J _C at all the investigated angular regimes. A possible mechanism of vortex pinning in samples with hybrid APCs is also discussed suggesting the role of 1D and 3D APCs.