Bias-Controlled Giant Magnetoresistance through Cyclopentadienyl-Iron Multidecker Molecules

We investigated giant magnetoresistance (GMR) across cyclopentadienyl-iron multidecker molecules [Fe-m(C5H5)] using the density functional theory and nonequilibrium Green's function techniques. An oscillation behavior of the molecular magnetic moments was observed. Spin-polarized transport calculations through the lead-multidecker molecule-lead junctions predicted large bias-controlled magnetoresistive response, with the highest GMR ratio up to 2.0 x 10(4)%. The positive to negative conversion of the GMR values was also observed with bias change. The transmission spectra and eigenvalues of the molecular junctions were calculated to understand the mechanism of spin transport in these systems. Various ways to manipulate the GMR behavior are illustrated, opening up prospects of new molecular spintronic devices.