Regensburg 2025 – scientific programme
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O: Fachverband Oberflächenphysik
O 68: Focus Session Molecular Nanostructures on Surfaces: On-Surface Synthesis and Single-Molecule Manipulation IV
O 68.5: Talk
Wednesday, March 19, 2025, 16:00–16:15, H24
A route toward the on-surface synthesis of organic ferromagnetic quantum spin chains — •Fabian Paschke1, Ricardo Ortiz2, Shantanu Mishra1, Manuel Vilas-Varela3, Florian Albrecht1, Diego Peña3, Manuel Melle-Franco2, and Leo Gross1 — 1IBM Research Europe - Zurich, 8803 Rueschlikon, Switzerland — 2CICECO - Instituto de Materiais de Aveiro, 3810-193 Aveiro, Portugal — 3CiQUS and Department of Organic Chemistry, 15782 Santiago de Compostela, Spain
Engineering a sublattice imbalance is an intuitive way to induce high-spin ground states in bipartite polycyclic conjugated hydrocarbons. Such high-spin molecules can be employed as building blocks of quantum spin chains, which are outstanding platforms to study many-body physics and fundamental models in quantum magnetism [1].
In contrast to antiferromagnetism, demonstration of ferromagnetic coupling between polycyclic conjugated hydrocarbons has been scarce. Here, we demonstrate the on-surface synthesis of short ferromagnetic spin chains based on dibenzotriangulene, a polycyclic conjugated hydrocarbon with a triplet ground state. We achieve a direct majority-minority sublattice coupling between adjacent units, which leads to a global sublattice imbalance in the chains and therefore a ferromagnetic ground state with a strong intermolecular ferromagnetic exchange. By means of scanning probe measurements and quantum chemistry calculations, we confirm quintet and septet ground states in dimers and trimers, respectively.
[1] S. Mishra et al., Nature 598, 287 (2021).
Keywords: On-surface synthesis; Scanning tunneling microscopy; Atomic force microscopy; Spin Chain; Nanographene