Electron transport across a quantum wire in the presence of electron leakage to a substrate

TL;DR

This paper studies electron transport in a quantum wire coupled to electrodes and a substrate, revealing how conductance oscillates with tip position and depends on substrate electron localization, with charge oscillations forming as a common feature.

Contribution

It models electron transport in a quantum wire with substrate leakage using a tight-binding approach and analyzes conductance oscillations and charge formation.

Findings

Conductance oscillates with tip position and varies with wire length.

Substrate electron localization significantly affects conductance.

Charge oscillations are a universal phenomenon observed in the system.

Abstract

We investigate electron transport through a mono-atomic wire which is tunnel coupled to two electrodes and also to the underlying substrate. The setup is modeled by a tight-binding Hamiltonian and can be realized with a scanning tunnel microscope (STM). The transmission of the wire is obtained from the corresponding Green's function. If the wire is scanned by the contacting STM tip, the conductance as a function of the tip position exhibits oscillations which may change significantly upon increasing the number of wire atoms. Our numerical studies reveal that the conductance depends strongly on whether or not the substrate electrons are localized. As a further ubiquitous feature, we observe the formation of charge oscillations.