Comunicazione
Properties of sputtered films of the electron-doped $Nd^{2-x}Ce^{x} CuO^{4-d}$ superconductor.
Nigro A., Guarino A., Autieri C., Marra P., Leo A., Grimaldi G., Avella A.
In $RE^{2-x}Ce^{x} CuO^{4-d} (RE=$ rare earth) electron-doped cuprates, the superconductivity is harder to achieve since as-grown samples are antiferromagnetic up to high doping levels, and become superconducting only after a specific annealing process. The role of the annealing treatment still constitutes an open question for $n-type$ superconductors. We investigate the electrical and structural properties of $Nd^{2-x}Ce^{x}CuO^{4-d}$ films grown by a sputtering technique in an oxygen-deficient environment, to obtain information on the complete oxygen-phase diagram. The as-grown samples are non-superconducting, and the structural properties are consistent with a deficiency of oxygen content. Unexpectedly, a reducing thermal treatment at high temperatures can induce superconductivity in these films. Our data support the picture that the high-temperature annealing procedure causes a peculiar oxygen atoms distribution triggering the superconducting transition in these compounds.