Multilayers of YBaCuO superconductors and Nihyphen;doped YBaCuO superconductors have been grown by the laser ablation technique to study the flux pinning properties of the nonmagnetic/magnetic superconducting heterostructures. Even though Ni doping depressed the superconducting properties of the single layer films, when sandwiched between high quality YBaCuO films, the composite showed high critical temperatures. Threehyphen;layer and fivehyphen;layer structures of the YBaCuO/YBaCuNiO system become superconducting around 87 K when the doped layer thickness was below 100 Aring;. Threehyphen;layer structures grown on ZrO2(100) showed critical current densities of 3times;106A/cm2at 77 K, which is about three times larger than the reported results in the literature. Epitaxial layer growth between the two superconductors was indicated by xhyphen;ray diffraction measurements, which showed completechyphen;axis orientation with full width at half maximum of 0.45deg; in a (006) line scan. Behavior of the critical current up to 0.85 T and temperatures down to 66 K has been studied. Critical current densities close to 4.5times;106A/cm2in 0.85 T fields perpendicular to the films have been obtained at 67 K.
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