Fabrication of Thick YBa2Cu3O7−x Films on Optimized SrTiO3 Buffered-MgO Single Crystals

In this work, we studied the optimum deposition conditions for SrTiO₃ (STO) buffers deposited on MgO single crystals substrates by PLD method. We found that 120 nm thick STO films, deposited at 730 ^oC , present the smoothest surface and a minimum FWMH of the (002) reflection. High quality, smooth and free-crack (YBCO) thick superconducting films have then been fabricated using a deposition temperature of 800 ^oC on STO-buffered MgO substrates. A 373 nm thick YBCO/STO/Mg₂O film can carry current densities (77 K, 0 T) of 1.4 MA/ cm² and J_c (77 K, 5 T) of 1.4 MA/ cm² The J_c in high field overcomes the current transported in same experimental conditions by 180 nm thick YBCO film grown on Y₂O₃ -decorated STO single crystal. For 1350 nm thick YBCO/STO/MgO film the J_c (77 K, 0 T) is about 0.8 MA/cm² and J_c (77 K, 5 T) is 0.09 MA/cm².