Dresden 2026 – scientific programme

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O: Fachverband Oberflächenphysik

O 99: Spins on surfaces at the atomic scale III

O 99.7: Talk

Friday, March 13, 2026, 11:00–11:15, WILL/A317

Spin and Charge States of Open-Shell Nanographenes over Functional Substrates — •Francisco Romero-Lara, Trisha Sai, Katerina Vaxevani, Dongfei Wang, Jon Ortuzar, Leonard Edens, Stefano Trivini, Fabian Schulz, and Jose Ignacio Pascual — CIC nanoGUNE, 20018 San Sebastián, Spain

Atomically precise open-shell nanographenes are platforms hosting spin states, which can be manipulated by local probes and by tuning their local environment. Here, we present the fabrication of aza-triangulenes-based nanostructures over two novel substrates with potential control over their charge and spin state: a rare-earth-gold alloy monolayer and a superconducting surface. The aza-triangulene platforms can host several weakly interacting spin states and a doublet ground state sensitive to Jahn-Teller distortion. We use scanning tunnelling microscopy to resolve their Kondo and spin excitation spectrum. We also resolve the presence of Yu-Shiba-Rusinov (YSR) states inside the proximity gap on the superconducting surface. Owing to an inhomogeneous local contact potential difference, the nanographenes on rare-earth-gold alloy surfaces appear with varying charge states depending on their adsorption site, which is also translated into variations of the spin ground state. Over a superconducting substrate, sub-gap spectral maps reveal with high precision their YSR excitations. They are interpreted based on a model theory as reflecting, in some cases, Jahn-Teller distortions. Overall, our results highlight the potential of unconventional substrates for on-surface nanographene synthesis and for tailoring and probing their intrinsic spin states.

Keywords: Nanographene; On-surface synthesis; Spin states; Kondo resonance; Yu-Shiba-Rusinov states