title: Field-induced conductance switching by charge-state alternation in organometallic single-molecule junctions.
abstract: Charge transport through single molecules can be influenced by the charge and spin states of redox-active metal centres placed in the transport pathway. These intrinsic properties are usually manipulated by varying the molecule's electrochemical and magnetic environment, a procedure that requires complex setups with multiple terminals. Here we show that oxidation and reduction of organometallic compounds containing either Fe, Ru or Mo centres can solely be triggered by the electric field applied to a two-terminal molecular junction. Whereas all compounds exhibit bias-dependent hysteresis, the Mo-containing compound additionally shows an abrupt voltage-induced conductance switching, yielding high-to-low current ratios exceeding 1,000 at bias voltages of less than 1.0 V. Density functional theory calculations identify a localized, redox-active molecular orbital that is weakly coupled to the electrodes and closely aligned with the Fermi energy of the leads because of the spin-polarized ground state unique to the Mo centre. This situation provides an additional slow and incoherent hopping channel for transport, triggering a transient charging effect in the entire molecule with a strong hysteresis and large high-to-low current ratios.
authors.affiliation: IBM Research - Zurich, Säumerstrasse 4, Rüschlikon 8803, Switzerland.
authors.forename: Florian
authors.initials: F
authors.lastname: Schwarz
authors.affiliation: Department of Physical Chemistry, University of Vienna, Sensengasse 8/7, Vienna 1090, Austria.|Institute for Theoretical Physics, TU Wien - Vienna University of Technology, Wiedner Hauptstrasse 8-10, Vienna 1040, Austria.
authors.forename: Georg
authors.initials: G
authors.lastname: Kastlunger
authors.affiliation: Department of Chemistry, University of Zürich, Winterthurerstrasse 190, Zürich 8057, Switzerland.
authors.forename: Franziska
authors.initials: F
authors.lastname: Lissel
authors.affiliation: Department of Chemistry, University of Zürich, Winterthurerstrasse 190, Zürich 8057, Switzerland.
authors.forename: Carolina
authors.initials: C
authors.lastname: Egler-Lucas
authors.affiliation: Department of Chemistry, University of Zürich, Winterthurerstrasse 190, Zürich 8057, Switzerland.
authors.forename: Sergey N
authors.identifier: http://orcid.org/0000-0002-5829-2283
authors.initials: SN
authors.lastname: Semenov
authors.affiliation: Department of Chemistry, University of Zürich, Winterthurerstrasse 190, Zürich 8057, Switzerland.
authors.forename: Koushik
authors.initials: K
authors.lastname: Venkatesan
authors.affiliation: Department of Chemistry, University of Zürich, Winterthurerstrasse 190, Zürich 8057, Switzerland.
authors.forename: Heinz
authors.initials: H
authors.lastname: Berke
authors.affiliation: Department of Physical Chemistry, University of Vienna, Sensengasse 8/7, Vienna 1090, Austria.|Institute for Theoretical Physics, TU Wien - Vienna University of Technology, Wiedner Hauptstrasse 8-10, Vienna 1040, Austria.
authors.forename: Robert
authors.initials: R
authors.lastname: Stadler
authors.affiliation: IBM Research - Zurich, Säumerstrasse 4, Rüschlikon 8803, Switzerland.
authors.forename: Emanuel
authors.initials: E
authors.lastname: Lörtscher