Charlier, Jean-ChristopheSalemi, LeandroLeandroSalemi2025-05-142025-05-142025-05-142017https://hdl.handle.net/2078.2/12353In this report, we use first-principles methods to investigate the spin-resolved transport proper- ties of zigzag graphene nanoribbons (ZGNRs) whose edges have been functionalized by phenyl groups. Electronic structure calculations rely on density functional theory (DFT) and transport properties are computed within the non-equilibrium Green’s functions (NEGF) formalism. The computational tools used in this work are the SIESTA (DFT) and TranSIESTA (NEGF) software. We first provide a review on the theoretical concepts behind DFT and NEGF formalim. Then, we analyse simpler systems such as pristine graphene and 6-ZGNRs. The case of a Stone-Wales defect is also treated. Finally the so-called phenyl-edge modified 6-ZGNRs (PEM 6-ZGNRs) are studied. It is found that such defects introduce a localized state within the band-gap of the 6-ZGNRs. When multiple phenyl groups lay on the edge, the distance between them has a significant influence on the electronic properties. The spin-resolved transmission spectrum for a 6-ZGNRs/PEM 6-ZGNRs junction is analysed and reveals interesting features that may lead to efficient spin filtering. To understand the effect of the phenyl groups on the conductance of 6-ZGNRs, 13 different edge topologies are computed within TranSIESTA. Common features appear for most of the structures. One of the most remarkable one is the appearance of enhanced back-scattering at the energy E = −0.48 eV in the ↑↓ edge polarization. When one of the edge is left pristine, it is found that this back-scattering only occurs for one spin channel and not the other. For the other polarization (↑↑), extinction of the conductance of one of the spin channel around the Fermi energy suggests a possible spin filter.GrapheneNanoribbonsQuantum TransportDFTNEGFtext::thesis::master thesisthesis:10679