Impact of van der Waals forces on the classical shuttle instability

TL;DR

This paper investigates how van der Waals forces influence the behavior of a single electron shuttle, revealing that these forces, combined with elastic forces, affect shuttle instability, trapping, and current flow, with notable hysteresis effects.

Contribution

It introduces a numerical analysis of van der Waals interactions in electron shuttles, highlighting their impact on instability and transport properties, which was not previously detailed.

Findings

Van der Waals forces significantly affect shuttle dynamics.

Weak elastic forces lead to grain trapping near leads.

Applying a threshold voltage induces grain motion and increased current.

Abstract

The effects of including the van der Waals interaction in the modelling of the single electron shuttle have been investigated numerically. It is demonstrated that the relative strength of the vdW-forces and the elastic restoring forces determine the characteristics of the shuttle instability. In the case of weak elastic forces and low voltages the grain is trapped close to one lead, and this trapping can be overcome by Coulomb forces by applying a bias voltage $V$ larger than a threshold voltage $V_{\rm u}$. This allows for grain motion leading to an increase in current by several orders of magnitude above the transition voltage $V_{\rm u}$. Associated with the process is also hysteresis in the I-V characteristics.