Finite bias spectroscopy of a three-terminal graphene quantum dot in the multi-level regime

TL;DR

This study investigates a three-terminal graphene quantum dot using finite bias spectroscopy, revealing complex conductance features likely due to strong coupling with excited states or lead density of states fluctuations in the multi-level transport regime.

Contribution

It provides the first detailed analysis of three-terminal graphene quantum dots in the multi-level regime, highlighting the role of excited states and lead density of states fluctuations.

Findings

Enhanced differential conductance lines observed outside Coulomb diamonds.

Lines likely due to strong coupling with a few excited states.

Lead density of states fluctuations may influence conductance features.

Abstract

Finite bias spectroscopy measurements of a three-terminal graphene quantum dot are presented. Numerous lines of enhanced differential conductance are observed outside the Coulomb diamonds. In the single-level transport regime such lines are often associated with transport through excited states. Here the system is in the multi-level transport regime. We argue that the lines are most likely a result of strong coupling to only a few of the excited states available in the bias window. We also discuss the option that fluctuations of the density of states in the leads are fully or partly responsible for the appearance of the lines. Such a detailed analysis requires the presence of three leads to the dot.