FLUX-PINNING IN NBTI NB MULTILAYERS

We made thin film multilayers of NbTi and Nb (d(NbTi) approximate to 2 0 nm and d(Nb) approximate to 3-9 nm), Samples were characterized by e lectrical transport measurements between 4.2 K and T-c, in magnetic fi elds up to 6 T. We present J(C) as a function of the device geometry a nd orientation of the field, For some multilayers, J(C) had a large pe ak whose onset occurs near similar to 0.2 H-c2. We suggest this peak e ffect is caused by a softening of the tilt modulus, Measured critical current densities at 4.2 K of 16 kA/mm(2) at 3 T and 8 kA/mm(2) at 5 T are among the highest achieved in the NbTi system.