Detecting the spin-polarization of edge states in graphene nanoribbons
Jens Brede, Néstor Merino‐Díez, Alejandro Berdonces‐Layunta, Sofía Sanz, Amelia Dominguez‐Celorrio, Jorge Lobo‐Checa, Manuel Vilas‐Varela, Diego Peña, Thomas Frederiksen, José Ignacio Pascual, Dimas G. de Oteyza, David Serrate
Abstract
Low dimensional carbon-based materials can show intrinsic magnetism associated to p-electrons in open-shell π-conjugated systems. Chemical design provides atomically precise control of the π-electron cloud, which makes them promising for nanoscale magnetic devices. However, direct verification of their spatially resolved spin-moment remains elusive. Here, we report the spin-polarization of chiral graphene nanoribbons (one-dimensional strips of graphene with alternating zig-zag and arm-chair boundaries), obtained by means of spin-polarized scanning tunnelling microscopy. We extract the energy-dependent spin-moment distribution of spatially extended edge states with π-orbital character, thus beyond localized magnetic moments at radical or defective carbon sites. Guided by mean-field Hubbard calculations, we demonstrate that electron correlations are responsible for the spin-splitting of the electronic structure. Our versatile platform utilizes a ferromagnetic substrate that stabilizes the organic magnetic moments against thermal and quantum fluctuations, while being fully compatible with on-surface synthesis of the rapidly growing class of nanographenes.