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

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 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 quantum gate.

Preparation of Multi‐Spin Systems: A Case Study of Tolane‐Bridged Verdazyl‐Based Hetero‐Diradicals

“…The purely organic high‐spin systems based on nitroxides, verdazyls, trityls, and phenoxides are widely applied as labels for structural studies of biological objects with the EPR technique, as agents for dynamic nuclear polarisation, and as potential components of a quantum computer Furthermore, such high‐spin paramagnets have been used for the tuning of magneto‐optic properties of a chiral polymer and fabrication of electronic devices, e.g., as electrochemical switchers and memory devices, hole‐transporting materials, and spin filters …”

Calix[n]arene-based polyradicals: enhancing ferromagnetism by avoiding edge effects

“…In fact, the validity of the B3LYP functional with the standard Pople-type GTO basis set to describe these types of organic radicals has been extensively validated in previous theoretical 21,71 and experimental 72,73 works. Taken altogether, one can safely conclude that a more exhaustive investigation of the potential energy surfaces will not reveal a qualitatively different picture in terms of magnetic interactions and that the presented cases are sufficiently representative.…”

Electrical and spin switches in single‐molecule junctions

“…The most commonly used molecules for spin switches contain spin‐crossover metal complexes and organic radical molecules. In this part, we will summarize the progress of single‐molecule spin switches in terms of external stimuli that trigger the switching process, including electric field, magnetic field and mechanical force …”

“…B, Structure of a neutral diradical molecule, differential conductance (red) and corresponding redox center spin value S (blue) as a function of V g . Reproduced with permission . Copyright 2017, American Chemical Society.…”

“…Apart from spin‐crossover metal complexes, the charge transport of all‐organic radical molecules has also been explored in single‐molecule junctions that showed switching effects. Three terminal devices based on a 2,4,6‐hexakis(pentachlorophenyl)mesitylene diradical molecule were fabricated by using feedback‐controlled electromigration (Figure B) . The neutral diradical molecule could undergo reversible and stable charges by means of a gate voltage.…”