CISS Effect: A Magnetoresistance through Inelastic Scattering

One of the manifestations of chirality-induced spin selectivity is the magnetoresistance (MR) in two-terminal transport measurements on molecular junctions. This paper investigates the effect of spin-orbit coupling in the leads on the polarization of the transmission. A helicene molecule between two gold contacts is studied using a tight binding model. To study the occurrence of MR, which is prohibited in coherent transport, as a consequence of the Büttiker reciprocity, we add Büttiker probes to the system in order to incorporate inelastic scattering effects. We show that for a strict two-terminal system without inelastic scattering, the MR is strictly zero in the linear and nonlinear regimes. We show that for a two-terminal system with inelastic scattering, a nonzero MR does appear in the nonlinear regime, reaching values of the order of 0.1%. Our calculations show that for a two-terminal system respecting time-reversal symmetry and charge conservation, a nonzero MR can only be obtained through inelastic scattering. However, spin-orbit coupling in the leads in combination with inelastic scattering modeled with the Büttiker probe method cannot explain the magnitude of the MR measured in experiments.