Charge and Spin Transport in Disordered Graphene-Based Materials - Dinh van Tuan Gebunden

This thesis presents an in-depth theoretical analysis of charge and spin transport properties in complex forms of disordered graphene. It relies on innovative real space computational methods of the time-dependent spreading of electronic wave packets. First a universal scaling law of the elastic mean free path versus the average grain size is predicted for polycrystalline morphologies and charge mobilities of up to 300.000 cm2 V.s are determined for 1 micron grain size while amorphous graphene membranes are shown to behave as Anderson insulators. An unprecedented spin relaxation mechanism u nique to graphene and driven by spin pseudospin entanglement is then reported in the presence of weak spin-orbit interaction (gold ad-atom impurities) together with the prediction of a crossover from a quantum spin Hall Effect to spin Hall effect (for thallium ad-atoms) depending on the degree of surface ad-atom segregation and the resulting island diameter.