Pinning and vortex lattice structure in NbTi alloy multilayers

• Published in: IEEE transactions on applied superconductivity 1997-06, Vol.7 (2), p.1134-1137
• Main Authors: McCambridge, J.D., Rizzo, N.D., Hess, S.T., Wang, J.Q., Ling, X.S., Prober, D.E., Motowidlo, L.R., Zeitlin, B.A.
• Format: Article
• Language: English
• Subjects: Applied sciences; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Conducting materials; Exact sciences and technology; Force measurement; Geometry; Lattices; Magnetic field measurement; Magnetic materials; Metals. Metallurgy; Multilayers, superlattices , heterostructures; Niobium compounds; Nonhomogeneous media; Physics; Properties of type I and type II superconductors; Superconducting films and low-dimensional structures; Superconductivity; Titanium compounds; Transistors; Vortex lattices ,flux pinning, flux creep
• ISSN: 1051-8223; 1558-2515
• DOI: 10.1109/77.620691

We made thin film multilayers of Nb/sub 0.37/Ti/sub 0.63//Nb and Nb/sub 0.37/Ti/sub 0.63//Ti (d/sub NiTi/=14-27 nm and d/sub N/=4-11 nm) to examine geometries and materials relevant to flux pinning in commercial NbTi conductors. Samples were characterized by transport measurements between 4.2 K and T/sub c/, in magnetic fields nearly parallel to the layers, up to 6 T. For some multilayers, pinning forces had a large peak at intermediate fields whose onset occurred near /spl sim/0.2 H/sub c2/. We suggest this peak effect is caused by a change in the vortex lattice structure, driven by the strong intrinsic pinning. We have measured the highest pinning force density (113 GN/m/sup 3/ at 4.2K and 5 T) ever achieved in the NbTi system.