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O: Fachverband Oberflächenphysik

O 93: Graphene II: Electronic Structure and Growth

O 93.4: Talk

Friday, March 31, 2023, 11:15–11:30, GER 37

Image potential states as local probes for graphene magnetism — •Maciej Bazarnik^1,2,3, Roland Wiesendanger³, and Anika Schlenhoff¹ — ¹Institute of Physics, University of Münster, Germany — ²Institute of Physics, Poznan University of Technology, Poland — ³Department of Physics, University of Hamburg, Germany

Image-potential states (IPSs) evolving in front of polarizable surfaces are known to serve as quantum sensors for various properties, including surface magnetization and interfacial coupling at buried interfaces. Using a spin-polarized scanning tunneling microscopy (SP-STM) setup, the spin-polarized IPS can be probed locally. In hybrid systems such as iron (Fe) -intercalated graphene (Gr) on Ir(111), Fe is known to grow pseudomorphically on the Ir substrate in a monolayer thickness limit. In contrast, the Gr overlayer exhibits a substantial buckling within the moiré unit cell, resulting in a laterally varying hybridization to the Fe. As a result, the monolayer Gr exhibits a laterally varying spin-polarization within the moiré unit cell.

Here, we present resonant tunneling studies on Fe-intercalated Gr, showing a much stronger contrast between the fcc and hcp parts of the moiré unit cell compared to conventional STM images on this system. Moreover, our SP-STM studies show that the IPSs are sensitive to the interlayer coupling of Gr to the underlying ferromagnet. The resulting local IPS spin-polarization can be used to probe the atomic-scale magnetism within the moiré unit cell of the ferromagnet graphene hybrid system.