IMX Colloquium - Designer Quantum Materials from Carbon

Atomically precise carbon nanostructures offer a new route to quantum systems built from the bottom up. By combining molecular design, on-surface synthesis and scanning probe microscopy, we can control atomic structure, electronic states and magnetic interactions within the same platform.
In this talk, I will follow the path from bottom-up synthesized graphene nanoribbons [1,2] to open-shell nanographenes [3] and designer quantum spin systems [4]. I will discuss how atomic structure can determine electronic topology and how molecular spins can be coupled into well-defined quantum chains. Recent examples include Haldane chains [4], alternating-exchange spin chains [5] and antiferromagnetic Heisenberg chains [6], where collective and fractional excitations can be probed directly at the atomic scale.
More broadly, this work illustrates a materials-science strategy in which structure, functionality and interactions are programmed at the level of molecular building blocks. Rather than optimizing properties in an existing material, the aim is to design the material and its quantum behavior together. Atomically precise carbon nanostructures therefore provide a model platform for exploring how synthesis, structure and emergent functionality can be linked in a predictive way, with implications for the future design of low-dimensional electronic, magnetic and quantum materials.

1. J. Cai, P. Ruffieux, R. Jaafar, et al., Nature 466, 470–473 (2010).
2. F. Xiang, Y. Gu, A. Kinikar, et al., Nat. Chem. 17, 1356–1363 (2025).
3. S. Mishra, D. Beyer, K. Eimre, et al., Nat. Nanotechnol. 15, 22–28 (2020).
4. S. Mishra, G. Catarina, F. Wu, et al., Nature 598, 287–292 (2021).
5. C. Zhao, G. Catarina, J.-J. Zhang, et al., Nat. Nanotechnol. 19, 1789-1795 (2024).
6. C. Zhao, L. Yang, J. C. G. Henriques, et al., Nat. Mater. 24, 722–727 (2025).