Magnetism created by a star-like arrangement of molecules: A star attraction.

Due to strong interactions between its electrons, a 2D nanomaterial made up of organic molecules coupled to metal atoms in a certain atomic-scale geometry has non-trivial electrical and magnetic properties.

Strong electron-electron interactions arise in a 2D organic material, according to a new study released today; these interactions are a direct result of the material's distinctive, star-like atomic-scale structure.

This is the first time that local magnetic moments have been observed as a result of electron interactions in an atomically thin 2D organic material.

The discoveries could be useful in next-generation electronics based on organic nanomaterials, where fine-tuning electron interactions can result in a wide range of electrical and magnetic phases and characteristics.

IN A 2D ORGANIC KAGOME MATERIAL, STRONG ELECTRON-ELECTRON INTERACTIONS

The Monash University research looked into a two-dimensional metal-organic nanomaterial made up of organic molecules arranged in a kagome geometry, or a'star-like' pattern.

Dicyanoanthracene (DCA) molecules are coordinated with copper atoms on a weakly interacting metal surface in this 2D metal-organic nanomaterial (silver).

The researchers discovered that the 2D metal-organic structure — whose molecular and atomic building components are non-magnetic in and of themselves — hosts magnetic moments restricted at certain spots using painstaking and atomically precise scanning probe microscopy (SPM) observations.

Theoretical calculations revealed that the strong electron-electron Coulomb repulsion caused by the particular 2D kagome geometry is responsible for the emergence of magnetism.

This, we believe, will be significant in the development of future organic electronics and spintronics technologies, where tweaking electron interactions can lead to control over a wide spectrum of electrical and magnetic properties.

DIRECT MAGNETISM EXAMINATION USING THE KONDO EFFECT

Due to destructive wavefunction interference and quantum localisation, electrons in 2D materials with a kagome crystal structure can be subjected to intense Coulomb interactions, resulting in a wide spectrum of topological and strongly correlated electronic phases.

Strong electrical correlations can lead to the formation of magnetism, which has never been detected in atomically thin 2D organic materials before. Due to its tunability and self-assembly capability, the latter can be advantageous for solid-state technology.

The Kondo effect was used to demonstrate magnetism caused by strong electron-electron Coulomb interactions in a 2D kagome organic material in this study.

"When magnetic moments are screened by a sea of conduction electrons, the Kondo effect arises, which is a many-body phenomena. For instance, starting with a base metal, "Dr. Dhaneesh Kumar, lead author and FLEET member, says "However, SPM approaches can identify this effect."

"The Kondo effect was observed, and we deduced that the 2D organic substance must include magnetic moments. 'Where does this magnetism come from?' became the next question."

Bernard Field and colleagues demonstrated conclusively that this magnetism is the direct result of strong Coulomb interactions between electrons using theoretical modeling. Only when the typically non-magnetic pieces are placed in a 2D kagome metal-organic framework do these interactions arise. These interactions prevent electron pairing, resulting in local magnetic moments caused by unpaired electron spins.

"This study's theoretical modeling provides a unique insight into the complexity of the interplay between quantum correlations, topological and magnetic phases. The research gives us a few ideas as to how these non-trivial phases in 2D kagome materials might be managed for possible applications in ground-breaking electronics technologies.