Magnetism of vacancies and edge states in graphene probed by electron spin resonance and scanning tunneling spectroscopy

• Applicants: Dr. Vladislav Kataev; Professor Dr. Markus Morgenstern
• Subject Area: Experimental Condensed Matter Physics
• Term: from 2016 to 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 282981637

We aim at a comprehensive understanding of spin interactions in graphene using well-defined magnetic defects as spin centers. The system is regarded as a paradigm for defect induced mag-netism, which is a controversially discussed subject in the literature [1-3]. While the Dirac point resonance and the paramagnetism of individual vacancies are experimentally well established for graphene, a systematic and quantitative study of their mutual interactions is missing. Based on a recent experiment where we have found a clear signature of preferential antiferromagnetic coupling between the vacancies [A1], we propose a systematic study by a combination of electron spin resonance and scanning tunneling spectroscopy including noise spectroscopy. We will determine the coupling constants as a function of electron density and vacancy density of graphene on various substrates using global electron spin resonance measurements. Moreover, we aim at a local detection of effective exchange interactions and resonance signals using scanning probe techniques. We will, moreover, develop the vacancies into zig-zag edges by controlled oxidation probing their spin properties by the same techniques. The resulting comprehensive understanding of spin coupling properties within graphene might serve as a blueprint for other systems with disordered magnetic impurities.

• DFG Programme: Research Grants
• International Connection: Israel
• International Co-Applicant: Professor Dr. Yishai Manassen