THE ELASTIC REGIME OF VORTICES IN SUPERCONDUCTING YBCO AND MULTILAYERYBCO PRBCO FILMS

A sensitive AC transport technique is used to determine the force-disp lacement response in the elastic regime of vortices pinned in YBCO and multilayer YBCO/PrBCO films. The dependences of the elastic limit of displacement and the Labusch parameter are presented as a function of temperature, magnetic-field amplitude and orientation. Results are pre sented for DC sputtered and laser-ablated epitaxial c-axis YBCO films as well as a DC sputtered multilayer YBCO/PrBCO film with a unit-cell ratio of 4:6. The elastic parameters enable the effective energy of th e pinning wells to be determined, and comparisons of these values are made with activation energies extracted from thermally activated flux- flow analyses of magneto-resistance data. The force-displacement value s show better agreement with magnetic-relaxation measurements than tho se from Arrhenius analyses.