title: Molecular spintronics: destructive quantum interference controlled by a gate.
abstract: The ability to control the spin-transport properties of a molecule bridging conducting electrodes is of paramount importance to molecular spintronics. Quantum interference can play an important role in allowing or forbidding electrons from passing through a system. In this work, the spin-transport properties of a polyacetylene chain bridging zigzag graphene nanoribbons (ZGNRs) are studied with nonequilibrium Green's function calculations performed within the density functional theory framework (NEGF-DFT). ZGNR electrodes have inherent spin polarization along their edges, which causes a splitting between the properties of spin-up and spin-down electrons in these systems. Upon adding an imidazole donor group and a pyridine acceptor group to the polyacetylene chain, this causes destructive interference features in the electron transmission spectrum. Particularly, the donor group causes a large antiresonance dip in transmission at the Fermi energy EF of the electrodes. The application of a gate is investigated and found to provide control over the energy position of this feature making it possible to turn this phenomenon on and off. The current-voltage (I-V) characteristics of this system are also calculated, showing near ohmic scaling for spin-up but negative differential resistance (NDR) for spin-down.
authors.affiliation: Centre for the Physics of Materials and Department of Physics, McGill University , Montreal, QC H3A 2T8, Canada.
authors.forename: Aldilene
authors.initials: A
authors.lastname: Saraiva-Souza
authors.forename: Manuel
authors.initials: M
authors.lastname: Smeu
authors.forename: Lei
authors.initials: L
authors.lastname: Zhang
authors.forename: Antonio Gomes
authors.initials: AG
authors.lastname: Souza Filho
authors.forename: Hong
authors.initials: H
authors.lastname: Guo
authors.forename: Mark A
authors.initials: MA
authors.lastname: Ratner