INFLUENCE OF DEPOSITION CONDITIONS AND ION IRRADIATION ON THIN-FILMS OF AMORPHOUS CU-ZR SUPERCONDUCTORS

Amorphous films of Cu-Zr have been prepared by electron-beam (e-beam) codeposition and ion beam mixing. Various treatments, such as depositi on onto liquid nitrogen cooled substrates and ion irradiation with 1 M eV Xe2+ ions or 500 keV Ar+ ions at 100 K and at 300 K, were used to v ary the level of disorder in the amorphous state. The residual resista nce ratio, the relative resistance change after irradiation, the tempe rature and width of the superconducting transition, and the upper crit ical field were measured and used to compare qualitatively the level o f disorder and homogeneity. The following observations could be made: (1) amorphous thin films, e-beam deposited at 300 K and below, are mor e disordered than amorphous ribbons; (2) ion irradiation with Xe and A r ions performed at 100 K and 300 K only leads to a slightly increased disorder level even for doses corresponding to about one displacement per atom; (3) ion irradiation gives rise to a homogenization of the s pecimens as evidenced by a decreasing width of the superconducting tra nsition; and (4) a significantly increased level of disorder is achiev ed by low-temperature deposition of very thin films.