I–V asymmetry and magnetoresistance in nickel nanoconstrictions

Abstract 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 magnetoresistance ratios exceeding 99.9%. We model a single point contact in a two-band tight-binding model as a 2×2 nickel chain connected to two semi-infinite nickel leads. The magnetoresistance is calculated by using a non-equilibrium Green's function technique.