Structural and electronic properties of graphitic nanowiggles

Abstract

Recent experiments have demonstrated a viable bottom-up strategy to produce narrow and highly ordered nanoribbons, including complex segmented structures called graphitic nanowiggles (GNWs). These defect-free systems are made of successive repetitions of finite-sized graphitic nanoribbons (GNRs) regularly connected at a given angle. Theoretical calculations have shown that these systems exhibit emergent and versatile properties at a level even higher than that found in their basic GNR constituents. Their main structural characteristic is the presence of multiple edge-dependent domains. This atomic structure has a marked influence on their physical properties since GNWs with at least one zigzag sector were shown to accommodate multiple magnetic states. The present detailed study shows how these properties vary with the details of the geometry. We also provide a quantum mechanics based explanation for the origin of GNW's multiple magnetic states. We find that the electronic structure of a GNW is sensitively dependent on the specific way its basic sectors are assembled, as well as on the details of the spin alignment along its edges. As a result, GNWs provide a new means to tune and design systems with desired electronic structure.2

Enhanced thermoelectric figure of merit in assembled graphene nanoribbons

“…We chose those spin configurations since only the PM spin ordering exists for AA GNWs and the AFM state is the most stable spin configuration for nanowiggles containing zigzag edges. 21,22 Each square represents the highest ZT peak value for a specific GNW structure, with the chemical potential ranging from −2 to 2 eV at room temperature. Due to the dependence of ZT on both electric and thermal conduction, it exhibits complex relations to geometrical parameters P and O.…”

“…For instance, in addition to conventional paramagnetic (PM), ferromagnetic (FM), and antiferromagnetic (AFM) spin configurations, AZ systems exhibit two more metastable states: longitudinal antiferromagnetic (LAFM) and transantiferromagnetic (TAFM). 21,22 We examine the influence of the magnetic states on ZT in Fig. 6.…”

“…20 These structures were predicted to possess atypical electronic and magnetic properties, showing a large variation of the band-gap values and the existence of many possible spin distributions, depending on the edge structures. 21,22 Because of the experimental feasibility to synthesize pure GNWs in a controlled way, and thanks to their remarkable electronic properties, it seems now increasingly possible to realize the promises of graphene-based nanostructures for thermoelectric applications.…”

Mechanical properties and fracture patterns of graphene (graphitic) nanowiggles

“…In (d) the dotted lines indicate the structural unit cell. For more details about GNW definition and structural characterizations, see reference [13]. 3 tion of their graphene-like strength [30,17].…”

“…The detailed knowledge of the mechanical properties of these materials is very important for the fabrication of nanodevices and for the exploita- For more details about GNW definition and structural characterizations, see reference [13]. tion of their graphene-like strength [30,17].…”