Dynamics of a nano-scale rotor driven by single-electron tunneling

We investigate theoretically the dynamics and the charge transport properties of a rod-shaped nano-scale rotor, which is driven by a similar mechanism as the nanomechanical single-electron transistor (NEMSET). We show that a static electric potential gradient can lead to self-excitation of oscillatory or continuous rotational motion. The relevant parameters of the device are identified and the dependence of the dynamics on these parameters is studied. We further discuss how the dynamics is related to the measured current through the device. Notably, in the oscillatory regime, we find a negative differential conductance. The current-voltage characteristics can be used to infer details of the surrounding environment which is responsible for damping.