Transport in single-molecule transistors: Kondo physics and negative differential resistance

TL;DR

This paper investigates transport phenomena in molecular-scale transistors, highlighting Kondo effects in C60 devices and negative differential resistance in control devices, emphasizing the importance of statistical analysis for device characterization.

Contribution

It presents evidence of Kondo physics and NDR in molecular transistors, and discusses criteria for confirming single-molecule transport and the origins of NDR.

Findings

Kondo signatures observed in C60-based single-molecule transistors

Gate-modulated negative differential resistance detected in control devices

Discussion on statistical methods for device characterization

Abstract

We report two examples of transport phenomena based on sharp features in the effective density of states of molecular-scale transistors: Kondo physics in C$_{60}$-based devices, and gate-modulated negative differential resistance (NDR) in ``control'' devices that we ascribe to adsorbed contamination. We discuss the need for a statistical approach to device characterization, and the criteria that must be satisfied to infer that transport is based on single molecules. We describe apparent Kondo physics in C$_{60}$-based single-molecule transistors (SMTs), including signatures of molecular vibrations in the Kondo regime. Finally, we report gate-modulated NDR in devices made without intentional molecular components, and discuss possible origins of this property.