Molecular Spintronics: Theory of Spin-Dependent Electron Transport Between Iron Nano-Contacts Bridged by Organic Molecules and Fe Atomic Chains*

Recent experiments [1] have lent support to theoretical predictions [2] that organic molecules connecting nickel nano-contacts may exhibit magneto-resistance and spin-valve effects. Here we present predictions of spintronic phenomena in another class of ferromagnetic nano-systems: Fe nano-contacts bridged by single conducting or insulating molecules or chains of Fe atoms. Models are constructed based on semi-empirical considerations, the known electronic structure of bulk Fe and ab initio density functional calculations. Using Lippmann-Schwinger and Green's function techniques, and Landauer theory, significant magneto-resistance is predicted in these systems. Under appropriate conditions, novel device characteristics such as negative magneto-resistance are also predicted to emerge. \newline \newline * Supported by NSERC and the Canadian Institute for Advanced Research. \newline 1 J. R. Petta et al., Phys. Rev. Lett. 93, 136601 (2004). \newline 2 E. G. Emberly and G. Kirczenow, Chem. Phys. 281, 311 (2002); R. Pati, et al., Phys. Rev. B 68, 100407 (2003).