Title :
Pinning and vortex lattice structure in NbTi alloy multilayers
Author :
McCambridge, J.D. ; Rizzo, N.D. ; Hess, S.T. ; Wang, J.Q. ; Ling, X.S. ; Prober, D.E. ; Motowidlo, L.R. ; Zeitlin, B.A.
Author_Institution :
Dept. of Appl. Phys., Yale Univ., New Haven, CT, USA
fDate :
6/1/1997 12:00:00 AM
Abstract :
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.
Keywords :
critical current density (superconductivity); flux pinning; flux-line lattice; niobium; niobium alloys; superconducting superlattices; superconducting thin films; titanium; titanium alloys; 0 to 6 T; Nb; Nb/sub 0.37/Ti/sub 0.63/; Nb/sub 0.37/Ti/sub 0.63//Nb; Nb/sub 0.37/Ti/sub 0.63//Ti; NbTi alloy multilayers; Ti; flux pinning; geometries; intermediate fields; pinning force density; strong intrinsic pinning; thin film multilayers; transport measurements; vortex lattice structure; Conducting materials; Force measurement; Geometry; Lattices; Magnetic field measurement; Magnetic materials; Niobium compounds; Nonhomogeneous media; Titanium compounds; Transistors;
Journal_Title :
Applied Superconductivity, IEEE Transactions on
