Spin interactions in organic molecular architectures

• Autores: Alessio Vegliante
• Directores de la Tesis: José Ignacio Pascual Chico (dir. tes.), Jose María Pitarque de la Torre (tut. tes.)
• Lectura: En la Universidad del País Vasco - Euskal Herriko Unibertsitatea ( España ) en 2025
• Idioma: inglés
• Programa de doctorado: Programa de Doctorado en Física de Nanoestructuras y Materiales Avanzados/Physics of Nanostructures and Advanced Materials por la Universidad del País Vasco/Euskal Herriko Unibertsitatea
• Calificación: Sobresaliente Cum Laude
• Materias:
  • Física
• Enlaces
  • Tesis en acceso abierto en: ADDI
• Resumen

  • This thesis investigates spin interactions in atomically precise organic nanostructures synthesized on metal substrates using on-surface synthesis techniques. While magnetism is usually associated with transition metals, it can also emerge in light elements like carbon through π-magnetism, driven by unpaired p-shell electrons. Magnetic carbon-based nanostructures are expected to exhibit unique properties such as enhanced spin delocalization and long coherence times, making them promising candidates for spintronics and quantum information applications.

    We employ scanning probe microscopy techniques—mainly scanning tunneling microscopy (STM) and spectroscopy (STS)—along with theoretical simulations to study various organic systems with differing numbers of unpaired π electrons. First, we investigate the magnetic properties of a non-planar organic diradical (2-OS) on a gold substrate, demonstrating how the exchange interaction depends on molecular conformation and how it can be modified by structural or chemical changes. Next, we explore more complex nanostructures, such as a triradical nanographene (TTAT), formed by joining three [3]triangulenes via a nitrogen-doped triangulene core. The resulting system exhibits a high-spin (S=3/2) ground state, as confirmed by STM and advanced multiconfigurational calculations. Similarly, we synthesize and characterize a [3]triangulene-based macrocycle (TNS), which accumulates twelve unpaired π electrons. We reveal that this nanostructure exhibits a many-body singlet ground state, with collective spin excitations accessible via inelastic electron tunneling spectroscopy. Finally, we explore strategies for fabricating two-dimensional covalent networks using open-shell triangulene units, with the aim of creating extended organic spin architectures.