Abstract
Graphene can develop large magnetic moments in custom-crafted open-shell nanostructures such as triangulene, a triangular piece of graphene with zigzag edges. Current methods of engineering graphene nanosystems on surfaces succeeded in producing atomically precise open-shell structures, but demonstration of their net spin remains elusive to date. Here, we fabricate triangulenelike graphene systems and demonstrate that they possess a spin ground state. Scanning tunneling spectroscopy identifies the fingerprint of an underscreened Kondo state on these flakes at low temperatures, signaling the dominant ferromagnetic interactions between two spins. Combined with simulations based on the meanfield Hubbard model, we show that this paramagnetism is robust and can be turned into an state by additional H atoms attached to the radical sites. Our results demonstrate that paramagnetism of high-spin graphene flakes can survive on surfaces, opening the door to study the quantum behavior of interacting spins in graphene systems.
- Received 16 October 2019
- Revised 17 February 2020
- Accepted 2 April 2020
DOI:https://doi.org/10.1103/PhysRevLett.124.177201
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