Edge disorder and magnetism in graphene nanoribbons: an inverse modelling approach

It is difficult to completely eliminate disorder during the fabrication of graphene-based nanodevices. From a simulation perspective, it is straightforward to determine the electronic transport properties of disordered devices if complete information about the disorder and the Hamiltonian describing it is available. However, to do the reverse and determine information about the nature of the disorder purely from transport measurements is a far more difficult task. In this work, we apply a recently developed inversion technique to identify important structural information about edge-disordered zigzag graphene nanoribbons. The inversion tool decodes the electronic transmission spectrum to obtain the overall level of edge vacancies in this type of device. We also consider the role of spin-polarised states at the ribbon edges and demonstrate that, in addition to edge roughness, the inversion procedure can also be used to detect the presence of magnetism in such nanoribbons. We finally show that if the transmission for both spin orientations is available, for example by using ferromagnetic contacts in a transport measurement, then additional structural information about the relative concentration of defects on each edge can be derived.