Influence of Annealing Temperature on Critical Current Densities in GdBa₂Cu₃O_7-δ Superconducting Thin Films Containing BaHfO₃ Nanocomposites

Abstract Oxygen annealing, an important step in acquiring RE Ba 2 Cu 3 O 7- δ superconducting thin films, is studied as a tool for pushing the critical current densities ( J c) of GdBa 2 Cu 3 O 7- δ (GdBCO) thin films containing 2.5 wt% BaHfO 3 (BHO) nanocomposites. All films are grown by a pulsed laser deposition (PLD) on MgO (100) single crystals. Oxygen annealing is performed in a tubular furnace ( ex-situ ) at 1 bar of oxygen pressure and at annealing temperatures ( T ann ) ranging between 450 °C and 780 °C. Field dependence of J c at 77 K shows an increase of J c from T ann = 450 °C and a maximum at T ann = 700 °C. At 10 K, the contribution to flux pinning from point-like defects is more prominent, somewhat in contrast trends seen at 77 K, however, the GdBCO film annealed at 700 °C shows the highest J c in 5-14 T magnetic field range.