Publications by John Gregg

I-V asymmetry and magnetoresistance in nickel nanoconstrictions

J MAGN MAGN MATER 272-76 (2004) 1571-1572

O Cespedes, AR Rocha, S Lioret, M Viret, C Dennis, JF Gregg, S van Dijken, S Sanvito, JMD Coey

We present a joint experimental and theoretical study on the transport properties of nickel nanoconstrictions. The samples show highly non-linear and asymmetric I-V characteristics when the conductance is smaller than G(0) = 2e(2)/h, and huge magneto resistance ratios exceeding 99.9%. We model a single point contact in a two-band tight-binding model as a 2 x 2 nickel chain connected to two semi-infinite nickel leads. The magnetoresistance is calculated by using a non-equilibrium Green's function technique. (C) 2003 Published by Elsevier B.V.

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