Critical current density enhancement in YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// thin films by twin domains of LaAlO/sub 3/ substrates

Magnetic flux penetration into a 0.2 /spl mu/m-thick YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// (YBCO) thin film grown on a crystalline LaAlO/sub 3/ (LAO) substrate was studied using magneto-optical imaging techniques. Enhanced critical current density J/sub c/ was observed at the location corresponding to twin domains on the underlying substrate. We attribute this J/sub c/ enhancement to increased pinning defects in the YBCO layer induced by the naturally formed nano-scaled surface roughness on the LAO substrate. Our results suggest that the substrate surface roughness might be helpful in J/sub c/ improvement of YBCO thin films grown on metal substrates by pulsed laser deposition.