ANISOTROPY AND LORENTZ-FORCE DEPENDENCE OF THE CRITICAL CURRENTS IN YBA2CU3O7-DELTA THICK-FILMS DEPOSITED ON NICKEL-ALLOY SUBSTRATES

We investigate the angular dependence of the critical currents in YBa( 2)Cn(3)O(7-delta) thick films deposited on metallic nickel-alloy subst rates, with the aid of an yttria-stabilized zirconia buffer layer. Ove rall, the critical current shows a clear Lorentz-force dependence and two distinctive peaks, one for fields parallel to the ab plane, due to bulk intrinsic pinning by the layered structure of the superconductor , and the other for fields parallel to the c axis, which we attribute to twin-boundary c-axis correlated pinning, as suggested by its Lorent z-force dependence.