Tunnel Magnetoresistance of the Heterocyclic Molecular Junctions: A Green’s Function Approach

We explore the spin-dependent transport properties in a molecular junction model made of heterocyclic molecules such as poythiophene, polyfuran, and polypyrrole sandwiched between ferromagnetic three-dimensional electrodes, hereafter named FM/h-molecule/FM junction, based on a tight-binding model and a generalized Green??s function method in the Landauer?CBüttiker formalism. The coherent spin-dependent transport through the energy levels of heterocyclic molecules, the transmittance, current?Cvoltage (I?CV) characteristics, and the tunnel magnetoresistance (TMR) of the FM/h-molecule/FM junction are numerically investigated. It is found that the spin-dependent transport properties are importantly influenced by the heteroatoms in the heterocyclic molecules. It is shown that the TMR of the molecular junction can be quite large (over 69?%) depending on the applied voltage and the molecular field of the FM electrodes.