The influence of low-temperature annealing on the physical properties of bi₂sr₂cacu₂cl y thin films

We have studied the low-temperature annealing effect on the physical properties of Bi₂Sr₂CaCu₂O_v thin films deposited on a MgO(lOO) substrate by rf magnetron sputtering. It is found that the characteristics of the films depend strongly on the oxygen partial pressure during re-annealing at 470°C after high-temperature annealing at 770°C in air. T_cand p at 300 K abruptly change for less than 20% oxygen partial pressure. A peak shift of the Bi4f core level spectrum is also observed at 0% oxygen partial pressure in an XPS measurement, which is due to the change in the ligand of the Bi atom.