Enhanced vertex pinning in annealed TlBa/sub 2/CaCu/sub 2/O/sub x/ thin films

Furnace anneals of TlBa/sub 2/CaCu/sub 2/O/sub x/ thin films at temperatures above 500/spl deg/C cause partial TlO/sub x/ loss. High resolution transmission electron microscopy images reveal nanometer-scale discontinuities (pinched stacking faults) in the microstructure of annealed films. Significant increases in the vortex pinning potential and critical current density at elevated temperatures in strong magnetic fields are observed and are attributed to the presence of these localized defects.