Uncovering the Magnetic Response of Open-Shell Graphene Nanostructures on Metallic Surfaces at Different Doping Levels

Open-shell graphene nanostructures (GNs) are promising candidates for future spintronics and quantum technologies. Recent progress based on on-surface synthetic approach has successfully created such GNs on metallic surfaces. Meanwhile, the doping effect of metallic surfaces is inevitably present and can significantly tune their electronic and magnetic properties. Here, we investigate the zigzag end states of open-shell 7-armchair graphene nanoribbons (7-AGNRs) on Au(111), Au(100) and Ag(111) surfaces. Combined with the manipulation of a scanning tunneling microscope, we demonstrate that the end states can be tuned from empty states to singly occupied states and to doubly occupied states by substrate doping. Furthermore, the singly occupied states can be finely tuned, with the occupancy number of the states and related magnetic behaviors uncovered by experiments at different temperatures and magnetic fields. Our results provide a comprehensive study of the magnetic response of open-shell GNs on metallic surfaces at different doping levels.