Vortex pinning by BaSnO$_{3}$--based correlated disorder in thick YBa$_{2}$Cu$_{3}$O$_{\sim 7}$ films: angular dependence of $J_{c}$ via contact-free methods

Pinning of vortices by second phase BaSnO$_{3}$ ``columnar defects'' has been studied in thick, $c$-axis oriented films of YBa$_{2}$Cu$_{3}$O$_{\sim 7}$, deposited epitaxially on (100) LaAlO$_{3}$. The dependence of the critical current density $J_{c}$ on orientation of the magnetic field was determined for temperatures $T$ = 77-5 K in applied magnetic fields $\mu _{0}H$ = 0-6 T. The contact-free inductive methods insured measurements at very low dissipation levels, with electric field $E \quad \sim $ 10$^{-10}$ V/cm. Results of this study will be compared and contrasted with findings for YBCO materials with a more complex pinning landscape from multiple defect types. Research at ORNL sponsored by Div. Materials Sciences and Engineering, USDOE. Work by CVV supported by AFOSR and Air Force Research Lab.