Manipulating Current Spin Polarization in Magnetic Single-Molecule Junctions via Destructive Quantum Interference

By means of the first-principles method, the effects of destructive quantum interference (DQI) on spin-dependent transport properties in meta-phenylene ethylene-type oligomer (OPE)-based magnetic single-molecule junctions are investigated. We explore one possible strategy to manipulate the spin polarization (SP) of current based on controllable DQI features using chemical substituents. It is found that the position of DQI features can obviously be tuned by inserting one nitrogen atom into the meta-OPE core at different positions, which leads to selected suppression of the transmission peaks contributed by the spin-resolved hybrid interface state (HIS). A resulting enhancement or reduction of the SP of current is achieved by manipulating the position of DQI dips. The nature of shift of the DQI feature is analyzed in terms of Green’s function and frontier molecular orbitals. In addition, such a phenomenon is further verified in the molecular junctions with side group substituents. This work demonstrates the role of controllable DQI in spin-dependent transport properties, which provides a feasible way to manipulate the spin functionality of organic spintronic devices.