Spin-Split Edge States in Metal-Supported Graphene Nanoislands Obtained by CVD

Spin-split states localized on zigzag edges have been predicted for different free-standing graphene nanostructures. However, the stability of the edge magnetism can be severely compromised by interfacial interactions when supported on metallic substrates. This imposes a serious challenge for the surface-assisted synthesis and characterization of magnetic graphene nanostructures, and their application in metal supports. In this work we demonstrate that graphene nanoislands with well-defined zigzag edges, synthesized by ultra-high vacuum chemical vapour deposition, can retrieve their spin-split edge states by minimizing interfacial interactions through metal intercalation. Using scanning tunneling microscopy and spectroscopy we detect edge states with subnanometer spatial localization and 1.2 eV energy splitting, comparable to the spin-polarized states predicted by ab-initio calculations. The fabrication of magnetic nanographenes by CVD opens a new avenue for the fabrication of 2D nanostructures that cannot be achieved by on-surface synthesis, and enables the implementation of demonstrated processes for scaling up synthesis.