title: Single-molecule electrochemical transistor utilizing a nickel-pyridyl spinterface.
abstract: Using a scanning tunnelling microscope break-junction technique, we produce 4,4'-bipyridine (44BP) single-molecule junctions with Ni and Au contacts. Electrochemical control is used to prevent Ni oxidation and to modulate the conductance of the devices via nonredox gating--the first time this has been shown using non-Au contacts. Remarkably the conductance and gain of the resulting Ni-44BP-Ni electrochemical transistors is significantly higher than analogous Au-based devices. Ab-initio calculations reveal that this behavior arises because charge transport is mediated by spin-polarized Ni d-electrons, which hybridize strongly with molecular orbitals to form a "spinterface". Our results highlight the important role of the contact material for single-molecule devices and show that it can be varied to provide control of charge and spin transport.
authors.affiliation: H. H. Wills Physics Laboratory, University of Bristol , Tyndall Avenue, Bristol BS8 1TL, United Kingdom.
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Brooke
authors.forename: Chengjun
authors.initials: C
authors.lastname: Jin
authors.forename: Doug S
authors.initials: DS
authors.lastname: Szumski
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Nichols
authors.forename: Bing-Wei
authors.initials: BW
authors.lastname: Mao
authors.forename: Kristian S
authors.initials: KS
authors.lastname: Thygesen
authors.forename: Walther
authors.initials: W
authors.lastname: Schwarzacher
mesh_terms: D006046:Gold; D009532:Nickel; D011725:Pyridines; D014173:Transistors, Electronic
chemical_list: D011725:Pyridines; D006046:Gold; D009532:Nickel
keywords: Single-molecule; break-junction; density functional theory; electrochemical gating; metal−molecule interface; spintronics