Y-Ba-Cu oxide films formed with pulsed-laser induced fragments

For the formation of Y-Ba-Cu oxide films by pulsed-laser sputtering, the dependence on laser energy density was first investigated over a wide range from 0.6 to 3 J/cm²at 1.064 µ m. Rutherford backscatteringspectrometry proved that the composition of deposited films strongly depends on the energy density. Films formed atanarrow window of laser energy density from the sputtering threshold of 0.6 J/cm²to 0.8 J/cm²showed superconductivity with a T_conset at 81 K and zero resistance at 79 K in spite of an excess of Cu and Ba atoms after annealing in oxygen. The X-ray diffraction patterns showed that these films have highly preferred orientation of the c-axis, and scanning electron microscopy exhibited the texture of highly dense grains with large sizes of about 5 µ m at the surface.