Large aromatic carbon nanostructures are cornerstone materials due to their increasingly role in functional devices. Among the many predicted applications, magnetism is the most unexpected one, but still an attractive challenge for its active role in spintronic devices. In our laboratories we aimed at exploring different methods for turning graphene nanoribbons (GNRs) magnetic using low temperature scanning tunneling microscopy (STM). The production of GNR can be realized with atomic precision on a metal surface using chemical strategies of on-surface synthesis, resulting in mostly defect-free ribbons and with a customized shape according to the utilized precursor. Magnetism can be induced by doping the carbon network with magnetic species. We incorporated magnetic molecular species into a ribbon using on-surface synthesis routes (see included image of a Fe porphyrin contacted to chiral nanoribbons) and proved that the molecular spin survives in the ribbon by using spin-excitation inelastic spectroscopy. Numerous predictions state that graphene can also spontaneously develop magnetism from the Coulomb repulsion of its pi-electrons. Crucial examples are the magnetization of zig-zag edges in graphene, or the emergence of paramagnetism in open shell graphenoid nanostructures. In this presentation, we will show the emergence of zero-energy edge modes in nanoribbons with a large density of zig-zag edges when a certain width is reached. In certain circumstances, the nanostructures exhibit spectroscopic fingerprints of spin localization, which allows us to identify and localize the sources of pi-paramagnetism with an STM.

Resumen del trabajo presentado al International workshop On-Surface Synthesis (OSS), celebrado en Sant Feliu de Guíxol (España) del 23 al 28 de septiembre de 2018.

Peer reviewed