Australian researchers are working on a new conductor that only conducts when needed. 

A new atomically-thin metal-organic material is being developed, capable of transitioning between insulating and conductive states. 

The technology could greatly enhance low-energy electronic devices, such as transistors for computing and electronic devices.

New research, conducted by the ARC Centre of Excellence in Future Low-Energy Electronics Technologies (FLEET) and published in Nature Communications, demonstrates the first known instance of a Mott insulating phase within a metal-organic framework (MOF). 

This phase allows the material to act both as an insulator and a conductor, depending on the electron population within it.

At the heart of the discovery is a MOF structured in a ‘kagome’ lattice - a pattern that enhances electron-electron interactions and enables the material to switch phases. 

“Thanks to the versatility of supramolecular chemistry approaches - in particular applied on surfaces as substrates - we have an almost infinite number of combinations to construct materials from the bottom-up, with atomic scale precision,” says Associate Professor Agustin Schiffrin from Monash University.

The researchers developed the kagome MOF using copper atoms and 9,10-dicyanoanthracene (DCA) molecules, grown on a hexagonal boron nitride (hBN) substrate. 

“We measured the structural and electronic properties of the MOF at the atomic scale using scanning tunnelling microscopy and spectroscopy,” says lead author Dr Benjamin Lowe. 

The measurements revealed an unexpected energy gap, a typical indicator of an insulating material.

The theoretical support for the experimental findings came from dynamical mean-field theory calculations, affirming the presence of a Mott insulating phase. 

“The electronic signature in our calculations showed remarkable agreement with experimental measurements,” says FLEET alum Dr Bernard Field.

The study also indicates the MOF's potential for integration into devices, given its ability to toggle between a Mott insulator and a metal phase by adjusting the electron population. 

This ability is particularly promising for applications in transistor technology, potentially leading to more efficient electronic devices.

The research team is now looking to reproduce its findings within an actual device structure, applying a uniform electric field across the material to further test its capabilities.