Browsing by Author "Thakur, Rajesh"

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    Stability and electronic properties of bilayer graphene spirals
    (Elsevier B.V., 2021-01-19T00:00:00) Thakur, Rajesh; Ahluwalia, P.K.; Kumar, Ashok; Sharma, Raman
    Spiral topology offers many potential applications to next-generation nanoelectronic devices. The ab-initio simulations are used to investigate the stability and electronic properties of the hexagonal and triangular double-layer spiral (DLS). A room temperature molecular dynamics (MD) simulation reveals that the AA stacking of triangular DLS (t-DLS) is thermodynamically stable, however, the AA stacking of hexagonal DLS (h-DLS)is found to get distorted. When h-DLS and t-DLS are subjected to tensile strain the h-DLS behaved elastically, however, the t-DLS is extremely brittle. Both h-DLS and t-DLS are observed to be metallic in an equilibrium state. On applying an electric field, the h-DLS remains metallic, whereas, the t-DLS becomes a semiconductor. The bandgap of t-DLS is observed to open up even for a small magnitude of electric field. Furthermore, we also found that the triangular-shaped bilayer spiral topology gives rise to an intrinsic Rashba splitting. Our study opens up new and innovative ideas for investigating the spiral-shaped nano-structures. � 2021 Elsevier B.V.
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    Twisted helical armchair graphene nanoribbons: mechanical and electronic properties
    (Springer Science and Business Media Deutschland GmbH, 2021-05-08T00:00:00) Thakur, Rajesh; Ahluwalia, P.K.; Kumar, Ashok; Sharma, Munish; Sharma, Raman
    Abstract: The Hydrogen and Fluorine planar armchairs graphene nanoribbons (H & F AGNRs), subjected to twist deformation within fixed periodic boundary conditions. H-AGNRs is highly elastic in nature, though passivation with Fluorine does induce the plasticity when twisted beyond threshold torsional strain. This plasticity attributes to the wider bond length distribution suggests distortion of benzo-rings. The bandgap response to the effective strain of narrow GNRs N= 6 , 7 , and 8 get arranged as (i) monotonously increasing for q= 0 , 2 and (ii) decreasing for q= 1 ; here, q= mod(N, 3) in effective strain space (?2?2). The effective strain space is found to be more appropriate for gauging the response of torsional strain. This trend has also been observed for Fluorine passivated AGNRs; however, because of higher sensitive response to torsional strain, the bandgap of N= 7 F-AGNRs drops from Eg? 0.95 eV to Eg? 0.05 eV at extreme torsional strain forming Dirac cone at � K allows dissipationless transport to charge carriers of high kinetic energy at low bias. Graphic abstract: [Figure not available: see fulltext.] � 2021, The Author(s), under exclusive licence to EDP Sciences, SIF and Springer-Verlag GmbH Germany, part of Springer Nature.