Controlling local currents in molecular junctions

TL;DR

This paper investigates how non-equilibrium conditions and dephasing influence circulating currents in molecular junctions, revealing how bias, magnetic fields, and asymmetry affect current pathways and suppression.

Contribution

It provides a detailed analysis of circulating currents under various conditions, including bias, magnetic fields, and asymmetry, highlighting mechanisms for controlling current flow in molecular systems.

Findings

Circulating currents can be induced by bias or magnetic fields.

Current suppression occurs due to competition between bias-driven and magnetic field-driven currents.

Asymmetry affects current pathways and can induce circulating currents without magnetic fields.

Abstract

The effect of non-equilibrium constraints and dephasing on the circulating currents in molecular junctions are analyzed. Circulating currents are manifestations of quantum effects and can be induced either by externally applied bias or an external magnetic field through the molecular system. In symmetric Aharonov-Bohm ring, bond currents have two contributions, bias driven and magnetic field driven. We analyze the competition between these two contributions and show that, as a consequence, current through one of the branches can be completely suppressed. We then study the effect of asymmetry (as a result of chemical substitution) on the current pathways inside the molecule and study asymmetry induced circulating currents (without magnetic field) by tuning the coupling strength of the substituent (at finite bias).