Inelastic transport in molecular spin valves: Calculations using the tight-binding Su-Schrieffer-Heeger model

We present a study of the effects of inelastic scattering on the transport properties of various nanoscale devices: namely, H₂ molecules sandwiched between Pt contacts and a spin valve made by an organic molecule attached to model half-metal ferromagnetic current-voltage probes. In both cases we use a tight-binding Su-Schrieffer-Heeger Hamiltonian and the inelastic effects are treated with a multichannel method, including the Pauli exclusion principle. In the case of the H₂ molecule, we find that inelastic backscattering is responsible for the drop of the differential conductance at biases larger than the excitation energy of the lower of the molecular phonon modes. In the case of the spin valve, we investigate the different spin currents and the magnetoresistance as a function of the position of the Fermi level with respect to the spin-polarized band edges. In general inelastic scattering reduces the spin polarization of the current and consequently the magnetoresistance.