Hour: From 10:30h to 11:30h
Place: Seminar Room
SEMINAR: Engineering spin and charge configurations in graphene architectures
Engineering correlated quantum states with atomic precision is a central challenge in solid-state quantum science. Graphene nanostructures synthesized on surfaces provide a controllable platform in which topology, electron count, and environment can be tuned at the single-molecule level, enabling the realization of designer many-body spin systems beyond conventional semiconductor systems.
Here, I will present an on-surface synthetic strategy to engineer and systematically tune spin states in aza-functionalized nanographenes and in chiral graphene nanoribbons. Inour studies, we combine low-temperature scanning probe microscopy with multireference quantum chemistry calculations to resolve the spatial distribution of frontier molecular orbitals, quantify spin densities, and elucidate the role of orbital filling and electron correlation in determining the magnetic ground state. These studies reveal how subtle changes in atomic structure and heteroatom incorporation reshape the balance between exchange interactions and electronic delocalization.
As a first example, I will present our work on aza-triangulene building blocks [2], which serve as versatile platforms to assemble increasingly complex nanographene architectures with electronic ground states ranging from high-spin configurations to topological polyradical systems [3–5]. In a second part, and if time allows, I will discuss chiral graphene nanoribbons (GNRs) synthesized on different surface platforms. While chiral GNRs host symmetry-protected topological end states, these states remain depopulated on Au(111) due to interfacial charge transfer. By engineering the substrate, i.e. tuning its work function, magnetic order, or superconducting properties, we demonstrate controlled modulation of charge and spin states, enabling activation and stabilization of correlated edge states.
[1] De Oteyza, D. G., Frederiksen, T., J. Phys.: Condens. Matter, 34, (2022) 443001
[2] Wang, T. et al J. Am. Chem. Soc., 144, (2022) 4522
[3] Vilas-Varela, M., Romero-Lara, F., et al., Angew. Chem. Int. Ed. 62, (2023) e202307884
[4] Vegliante, A. et al., J. Am. Chem. Soc. (2025) J. Am. Chem. Soc. 147, 19530 (2025)
[5] Romero-Lara, F. et al. arXiv:2512.10869 (2025)
Hour: From 10:30h to 11:30h
Place: Seminar Room
SEMINAR: Engineering spin and charge configurations in graphene architectures
Engineering correlated quantum states with atomic precision is a central challenge in solid-state quantum science. Graphene nanostructures synthesized on surfaces provide a controllable platform in which topology, electron count, and environment can be tuned at the single-molecule level, enabling the realization of designer many-body spin systems beyond conventional semiconductor systems.
Here, I will present an on-surface synthetic strategy to engineer and systematically tune spin states in aza-functionalized nanographenes and in chiral graphene nanoribbons. Inour studies, we combine low-temperature scanning probe microscopy with multireference quantum chemistry calculations to resolve the spatial distribution of frontier molecular orbitals, quantify spin densities, and elucidate the role of orbital filling and electron correlation in determining the magnetic ground state. These studies reveal how subtle changes in atomic structure and heteroatom incorporation reshape the balance between exchange interactions and electronic delocalization.
As a first example, I will present our work on aza-triangulene building blocks [2], which serve as versatile platforms to assemble increasingly complex nanographene architectures with electronic ground states ranging from high-spin configurations to topological polyradical systems [3–5]. In a second part, and if time allows, I will discuss chiral graphene nanoribbons (GNRs) synthesized on different surface platforms. While chiral GNRs host symmetry-protected topological end states, these states remain depopulated on Au(111) due to interfacial charge transfer. By engineering the substrate, i.e. tuning its work function, magnetic order, or superconducting properties, we demonstrate controlled modulation of charge and spin states, enabling activation and stabilization of correlated edge states.
[1] De Oteyza, D. G., Frederiksen, T., J. Phys.: Condens. Matter, 34, (2022) 443001
[2] Wang, T. et al J. Am. Chem. Soc., 144, (2022) 4522
[3] Vilas-Varela, M., Romero-Lara, F., et al., Angew. Chem. Int. Ed. 62, (2023) e202307884
[4] Vegliante, A. et al., J. Am. Chem. Soc. (2025) J. Am. Chem. Soc. 147, 19530 (2025)
[5] Romero-Lara, F. et al. arXiv:2512.10869 (2025)