Attenuation of Conductance
in Cobalt Extended Metal
Atom Chains
- Publication date
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Abstract
Density functional theory, in conjunction with nonequilibrium
Green’s
functions, is used to explore the attenuation of the resistance of
Co<sub><i>x</i></sub> wires along the series Co<sub>3</sub>(dpa)<sub>4</sub>(NCS)<sub>2</sub>, Co<sub>5</sub>(tpda)<sub>4</sub>(NCS)<sub>2</sub>, and Co<sub>7</sub>(teptra)<sub>4</sub>(NCS)<sub>2</sub>. At very low bias (0 < <i>V</i> < 25 mV)
the conductance, <i>G</i>, decreases in the order <i>G</i>(Co<sub>3</sub>) > <i>G</i>(Co<sub>5</sub>) > <i>G</i>(Co<sub>7</sub>), consistent with experiment
and with an
anticipated inverse relationship between conductance and chain length.
At higher voltages, however, the current–voltage responses
of all three are striking nonlinear, and above 50 mV <i>G</i>(Co<sub>5</sub>) > <i>G</i>(Co<sub>3</sub>) > <i>G</i>(Co<sub>7</sub>). The very different behavior of the members
of this
homologous series can be traced to the different symmetries and multiplicities
of their respective ground states, which in turn control the properties
of the dominant transport channels
