Negative differential electrical resistance of a rotational organic   nanomotor
  A robust nanoelectromechanical switch is proposed based upon an asymmetric pendant moiety anchored to an organic backbone between two C60 fullerenes, which in turn are connected to gold electrodes. Ab initio density functional calculations are used to demonstrate that an electric field induces rotation of the pendant group, leading to a non-linear current-voltage relation. The non-linearity is strong enough to lead to negative differential resistance at modest source-drain voltages. 
Hatef Sadeghi, Sara Sangtarash, Qusiy Al-Galiby, Rachel Sparks, Steven   Bailey and Colin J. Lambert
cond-mat.mes-hall