Nicholas D. Rizzo

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Spin-transfer in nanometre-scale magnetic devices results from the torque on a ferromagnet owing to its interaction with a spin-polarized current and the electrons' spin angular momentum. Experiments have detected either a reversal or high-frequency (GHz) steady-state precession of the magnetization in giant magnetoresistance spin valves and magnetic tunnel(More)
Scanning tunneling microscopy and spectroscopy are employed in studies of the proximity effect between normal metals and superconductors. The experimental configuration is unique, in that the tunneling current flows in parallel to the interfaces between different materials. The samples are superconducting wires consisting of ordered arrays of submicron(More)
Rapid advances in portable communication and computing systems are creating an increasing demand for nonvolatile random access memory that is both high-density and highspeed. Existing solid-state technologies are unable to provide all of the needed attributes in a single memory solution. Therefore, a number of different memories are currently being used to(More)
We made thin filmmultilayers of NbTi and Nb (dmTi = 20 nm and dNb = 3-9 nm). samples were characterized by electrical transport measurements between 4.2 K and T,, in magnetic fields up to 6 T. We present Jc as a function of the device geometry and orientation of the field. For some multilayers, Jc had a large peak whose onset occurs near * 0.2 He2. We(More)
We used ferromagnetic artificial pinning centers in superconducting NbTi wires to achieve a large critical current density (Jc) in a magnetic field. Four wires were fabricated that contained nanometer-sized arrays of Ni or Fe pins inside micron-sized filaments of Nb0.36Ti0.64 alloy. A ferromagnetic pin volume of only 2% Ni produced Jc’s ~e.g., 2500 A/mm 2(More)
We report on transport properties of the vortex lattice in fine, round NbTi wires fabricated by a novel wire-drawing process. The voltage onset in the isothermal I-V characteristic is sharp for thick wires sd $ 1 mmd at 4.2 K and 6 T, but is rounded for thinner wires. The thinnest wires also display an Ohmic resistivity at low current densities. This linear(More)
Scanning tunneling microscopy and spectroscopy are employed in order to map with nanometer resolution the local quasi-particle density of states in superconducting proximity structures. Our experimental configuration is unique, in that the tunneling current flows in parallel to the interfaces between different materials. We focus here on the measurement of(More)
W e made thin film multilayers o f Nb,,.37Ti,,63/Nb and Nbo.3,Tio.63/Ti (dNbTl = 14 27 nm and d , = 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 , , i n magnetic fields nearly parallel to the layers, up to 6 T. For some(More)
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