Describing the spin-polarized transport in molecular junctions by ab-initio calculations.
Applying ab-initio density functional theory we study structural properties of simple organic
molecules between metallic leads. Combining density functional theory with the nonequilibrium
Green function approach we investigate the spin-dependent transport properties
in these systems. Our molecular system of choice include cobaltocence as well as
the metal-benzene multiple-decker sandwiches Xn(C6H6)m with transition-metal centers,
X=V, Nb, Ta, and their functionalized derivatives. These molecules will be attached to
Cu leads. The transition-metal ion X in these molecules induces a magnetic moment and
the spin-dependent conductance through the molecules will be studied as function of the
ordering of these moments (ferromagnetic, antiferromagnetic, noncollinear), and of relative
orientation of these moments with respect to the molecule leading to a ballistic anomalous
magnetoresistance due to the effect of the spin-orbit interaction. Ferromagnetic leads are
explored as spin-injectors. Local correlation effects on the molecule and the charging of
the molecules as a function of the details of the absorption and the applied bias will be
investigated including correction beyond conventional density functional theory methods.
To achieve these goals the ab-initio methods are developed in various directions including
the implementation of an all-electron transport scheme for one-dimensional molecular
structures attached to semi-infinite surfaces and a suitable scheme for the self-interaction
correction.