Critical current density variations with increasing thickness in YBa$_{2}$Cu$_{3}$O$_{7-x}$+ BaSnO$_{3}$ (BSO) films

To increase the engineering critical current density (J$_{e})$ of YBa$_{2}$Cu$_{3}$O$_{7-x}$ (YBCO) films, it is of great importance to grow thicker films with high critical current density (J$_{c})$. However, it has been shown that in pulsed laser ablated (PLD) YBCO films, as the thickness is increased beyond 1 $\mu $m, the J$_{c}$ of the films decreases. Earlier work by this group showed that YBCO+BaSnO$_{3}$ (BSO) films of $\sim $ 300 nm thickness can be grown with more than an order of magnitude increase in the J$_{c}$ in applied magnetic fields using a dual phase sector PLD target approach. In the present work a systematic study of J$_{c}$ dependence on the thickness of YBCO+BSO thick films was undertaken by growing different films with thicknesses ranging from 300 nm to 4 $\mu $m. The J$_{c}$ of these films was measured using a magnetometer indicated that high J$_{c}$ at high fields can be maintained even in thicker films. The cross-sectional TEM analyses of the thick films showed that the BSO nanocolumns grow through out the entire thickness of the samples. Microstructural details and the superconducting properties of thick YBCO+BSO films will be presented.