Redox-Induced Gating of the Exchange Interactions in a Single Organic Diradical

TL;DR

This study demonstrates how redox-induced charging of an organic diradical molecule can reversibly control its magnetic exchange interactions, enabling potential applications in molecular spintronics and quantum computing.

Contribution

It provides a novel method for electrically controlling magnetic interactions within a single organic molecule using redox chemistry, demonstrated through inelastic electron tunneling spectroscopy.

Findings

Reversible charging alters the magnetic coupling in the molecule.

Added electron creates a new spin pathway, switching magnetic interactions.

The system functions as a prototype for a single-molecule quantum gate.

Abstract

Embedding a magnetic electroactive molecule in a three-terminal junction allows for the fast and local electric field control of magnetic properties desirable in spintronic devices and quantum gates. Here, we provide an example of this control through the reversible and stable charging of a single all-organic neutral diradical molecule. By means of inelastic electron tunnel spectroscopy (IETS) we show that the added electron occupies a molecular orbital distinct from those containing the two radical electrons, forming a spin system with three antiferromagnetically-coupled spins. Changing the redox state of the molecule therefore switches on and off a parallel exchange path between the two radical spins through the added electron. This electrically-controlled gating of the intramolecular magnetic interactions constitutes an essential ingredient of a single-molecule $\sqrt{\text{SWAP}}$ quantum gate.