Oleg V. Yazyev

Defect-induced magnetism in graphene

We study from first principles the magnetism in graphene induced by single carbon atom defects. For two types of defects considered in our study, the hydrogen chemisorption defect and the vacancy defect, the itinerant magnetism due to the defect-induced extended states has been observed. Calculated magnetic moments are equal to 1

Electronic transport in polycrystalline graphene

\mu_B

Emergence of magnetism in graphene materials and nanostructures

per hydrogen chemisorption defect and 1.12

Topological defects in graphene: dislocations and grain boundaries

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Spatially resolving edge states of chiral graphene nanoribbons

1.53

Magnetic correlations at graphene edges: Basis for novel spintronics devices

\mu_B

Magnetism in Disordered Graphene and Irradiated Graphite

per vacancy defect depending on the defect concentration. The coupling between the magnetic moments is either ferromagnetic or antiferromagnetic, depending on whether the defects correspond to the same or to different hexagonal sublattices of the graphene lattice, respectively. The relevance of itinerant magnetism in graphene to the high-

Spin Polarization and Transport of Surface States in the Topological Insulators Bi2Se3 and Bi2Te3 from First Principles

T_C

Polycrystalline graphene and other two-dimensional materials

magnetic ordering is discussed.

Topological Frustration in Graphene Nanoflakes: Magnetic Order and Spin Logic Devices

Most materials in available macroscopic quantities are polycrystalline. Graphene, a recently discovered two-dimensional form of carbon with strong potential for replacing silicon in future electronics, is no exception. There is growing evidence of the polycrystalline nature of graphene samples obtained using various techniques. Grain boundaries, intrinsic topological defects of polycrystalline materials, are expected to markedly alter the electronic transport in graphene. Here, we develop a theory of charge carrier transmission through grain boundaries composed of a periodic array of dislocations in graphene based on the momentum conservation principle. Depending on the grain-boundary structure we find two distinct transport behaviours--either high transparency, or perfect reflection of charge carriers over remarkably large energy ranges. First-principles quantum transport calculations are used to verify and further investigate this striking behaviour. Our study sheds light on the transport properties of large-area graphene samples. Furthermore, purposeful engineering of periodic grain boundaries with tunable transport gaps would allow for controlling charge currents without the need to introduce bulk bandgaps in otherwise semimetallic graphene. The proposed approach can be regarded as a means towards building practical graphene electronics.