PhD thesis defense. Charge and Spin Excitations in Triangulene Nanostructures on Functional Surfaces

This thesis investigates the fabrication and control of electronic spins in open-shell nanographenes. These carbon-based nanostructures exhibit unique magnetic properties and hold strong potential for spintronics and quantum information technologies. Their high reactivity makes them difficult to obtain using conventional methods. Using low-temperature, ultra-high-vacuum scanning tunneling microscopy (STM), new synthetic strategies are explored based on central heteroatom doping and geometric modification of triangulenes. Different spin configurations are induced, including highly correlated and multiradical states. The spin states are inferred through comparison between experimental measurements and theoretical calculations. Furthermore, the role of the substrate in the electronic and magnetic properties of these molecules is analyzed. Several gold-based surfaces are developed—including intermetallic alloys with rare-earth elements, superconducting proximitized films, and insulating MoS2 layers—which enable, respectively, modulation of charge transfer, improved spectral resolution, and different degrees of electronic decoupling. Overall, this work demonstrates atomic-precision control of π-magnetism in nanographenes and expands the experimental toolbox for their study and potential integration into devices.