PhD: Pedro Alcázar Guerrero

Directors:

Directors: Dr Aron Cummings (Theoretical and Computational Nanoscience), ICREA Prof. Stephan Roche (Theoretical and Computational Nanoscience) and ICREA Prof. Sergio O. Valenzuela (Physics and Engineering of Nanodevices) at ICN2.

Short Abstract:

This thesis investigates the influence of superperiodicity, quasiperiodicity, and disorder on electronic and spin transport in graphene-based systems. Large-scale atomistic real-space quantum-transport methods are employed to characterize the differences between periodic and quasiperiodic dynamics. In magic-angle twisted bilayer graphene, moderate disorder is shown to induce delocalization and increase the mean free path, a phenomenon connected to the quantum metric of the electronic states. Sub-ballistic transport and self-similar spatial patterns are also identified in quasicrystalline structures, although these features are highly sensitive to disorder and interlayer coupling.

Finally, atomic corrugations in suspended graphene are found to generate fluctuating Rashba fields that limit spin lifetimes, even when charge transport remains nearly ballistic. These findings establish a unified relationship between geometry, structural complexity, disorder, and quantum transport in twisted and corrugated graphene systems.

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