Magnetic Properties of Graphene and Related Nanomaterials

Graphene, a two-dimensional carbon framework, has spurred intensive research into its magnetic signatures. In its pristine form, graphene is typically non-magnetic due to delocalised π-electron clouds. However, through structural modulation, chemical functionalisation and atomic-scale doping, researchers have engineered magnetism in graphene and its derivatives. Tuning of hybridisation from sp2 to sp3 via covalent attachments (for instance, hydroxyl or fluorine substitution) introduces localised magnetic moments. Incorporation of transition-metal atoms or nitrogen heteroatoms yields robust ferromagnetic ordering at or above room temperature. Such developments have established graphene-based nanomaterials as promising candidates for spintronics, magnetic sensors and quantum devices. Advances in theoretical modelling have clarified mechanisms including superexchange interactions, diradical formation and conduction-electron mediated coupling. Practical realisations now extend from organic carbon magnets to metal-doped lattices, opening pathways to flexible, lightweight magnetic systems with controllable Curie temperatures and anisotropies.

Research from Nature Portfolio

Room-temperature organic magnets have been achieved by converting regions of graphene into an sp3-rich matrix through hydroxyl substitution, yielding antiferromagnetic ordering at room temperature and a transition to a ferromagnetic state upon cooling, driven by diradical motifs and superexchange networks. Separately, embedding isolated cobalt atoms bound to nitrogen coordination sites in the graphene lattice has delivered ferromagnetism with a Curie temperature approaching 400 K and substantial saturation magnetisation. In this system, hybridisation between cobalt d electrons and graphene π-electrons fosters long-range magnetic coupling, demonstrating an effective route to all-carbon spintronic platforms with transition-metal centres.

Magnetic Properties of Graphene and Related Nanomaterials publication trend

The graph below shows the total number of articles in magnetic properties of graphene and related nanomaterials across all publications each year (not limited to Nature Index journals).

Technical terms

Ferromagnetism: Ordering of magnetic moments parallel to each other, resulting in a net magnetic moment.

Antiferromagnetism: Alignment of neighbouring magnetic moments in opposite directions, cancelling macroscopic magnetism.

Curie temperature (TC): The temperature above which a ferromagnet loses its permanent magnetisation.

sp2 and sp3 hybridisation: Electronic configurations of carbon atoms; sp2 yields planar π-bonding, sp3 yields tetrahedral σ-bonds.

Diradical motif: A pair of unpaired electrons located on adjacent atoms, leading to localised magnetic moments via π-conjugation.

Superexchange interaction: Indirect magnetic coupling between non-adjacent centres mediated by a non-magnetic atom or ligand.

References

1. Room temperature organic magnets derived from sp3 functionalized graphene. Nature Communications (2017).
2. Embedding atomic cobalt into graphene lattices to activate room-temperature ferromagnetism. Nature Communications (2021).
3. Universal magnetic properties of sp3-type defects in covalently functionalized graphene. New Journal of Physics (2012).
4. A defective graphene phase predicted to be a room temperature ferromagnetic semiconductor. New Journal of Physics (2008).
5. Indirect Exchange and Ruderman–Kittel–Kasuya–Yosida (RKKY) Interactions in Magnetically-Doped Graphene. Crystals (2013).
6. Hybrid Reduced Graphene Oxide with Special Magnetoresistance for Wireless Magnetic Field Sensor. Nano-Micro Letters (2020).