Departamento de Física de la Materia Condensada – Instituto de Nanociencia y Nanotecnología, Centro Atómico Constituyentes, Comisión Nacional de Energía Atómica.
«Effects of Molecular Adsorption on Dirac Fermions at the Surfaces of Topological Insulators»
Topological insulators are a novel class of quantum materials characterized by an insulating bulk and robust two-dimensional conducting surface states protected by symmetry. These states host Dirac fermions with a distinctive spin–momentum locking, which suppresses backscattering and makes them highly appealing for technological applications in spintronics and quantum devices.
In realistic environments, however, surfaces are rarely pristine and are exposed to the surroundings. Understanding how these topological states interact with molecular adsorbates is therefore essential. In this talk, we explore whether and how Dirac surface states can be manipulated, controlled, or perturbed through the adsorption of small molecules such as O2, CO, or open-shell species like NO. Another important question is whether Dirac fermions themselves may influence or even catalyze chemical reactions at the surface. Studying the adsorption process can help address this question.
Our approach combines first-principles density functional theory (DFT) calculations of the electronic band structure with effective Hamiltonian models. This multiscale framework allows us to characterize the interaction between adsorbed molecules and topological surface states, and to analyze the resulting modifications in spin textures and transport properties. In particular, we evaluate possible changes in the Hall conductance induced by molecular adsorption.