Magnetic field control of current through model graphene nanosheets

Dhakal, Umesh; Rai, D.K.

doi:10.1016/j.physleta.2019.04.018

Cited by 4 publications

(2 citation statements)

References 65 publications

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“…For example, it has been suggested that helical currents around an axis can induce a unidirectional rotation in the molecule due to the conservation of the total angular momentum, , thus making the linear segment of the molecule function as a current-driven motor. The circular movement of charge will also generate a local unidirectional magnetic field in the molecule, , which may allow for magnetic control of the single-molecule conductance, − a direction we are working toward exploring. Realizing the potential of helical currents in truly linear molecules poses an interesting challenge for the field of molecular electronics.…”

Section: Discussionmentioning

confidence: 99%

Three Distinct Torsion Profiles of Electronic Transmission through Linear Carbon Wires

2020

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The one-dimensional carbon allotrope carbyne, a linear chain of sp-hybridized carbon atoms, is predicted to exist in a polyynic and a cumulenic structure. While molecular forms of carbyne have been extensively characterized, the structural nature is hard to determine for many linear carbon wires that are made in-situ during pulling experiments. Here, we show that cumulenes and polyynes have distinctively different low-bias conductance profiles under axial torsion. We analyze the change of the electronic structure, Landauer transmission, and ballistic current density of the three types of closed-shell molecular carbynes as a function of the torsion angle. Both polyynic, odd-carbon cumulenic, and even-carbon cumulenic carbon wires exhibit helical frontier molecular orbitals when the end-groups are not in a co-planar configuration. This helical conjugation effect gives rise to strong ring current patterns around the linear wires. Only the transmission of even-carbon polyynic wires follows the well-known cosine-squared law with axial torsion that is also seen in biphenyl-type systems. Notably, the transmission of even-carbon cumulenic carbon wires rises with axial torsion from co-planar towards perpendicular orientation of the end-groups. The three distinct transmission profiles of polyynes, odd-carbon cumulenes, and even-carbon cumulenes may allow for experimental identification of the structural nature of linear carbon wires. Their different electron transport properties under axial torsion furthermore underline that, in the molecular limit of carbyne, three different subclasses of linear carbon wires exist. File list (3)download file view on ChemRxiv torsion_chemrxiv3.pdf (6.17 MiB) download file view on ChemRxiv SI_chemrxiv3.pdf (9.24 MiB) download file view on ChemRxiv files.zip (21.38 MiB)

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Section: Discussionmentioning

confidence: 99%

Three Distinct Torsion Profiles of Electronic Transmission through Linear Carbon Wires

2020

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“…as shown in Figs.1 and 2. This is a known appropriate representation of nanosized graphene sheets (called also graphene quantum dots) 12,14 , artificial molecules composed of connected quantum dots [15][16][17] or alternant chemical molecules described by the Hückel Hamiltonian 1,18,19 .…”

Section: The Landauer Formalismmentioning

confidence: 99%

Robust conductance zeros in graphene quantum dots and other bipartite systems

2020

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Within the Landauer transport formalism we demonstrate that conductance zeroes are possible in bipartite systems at half-filling when leads are contacted to different sublattice sites. In particular, we investigate the application of this theory to graphene quantum dots with leads in the armchair configuration. The obtained conductance cancellation is robust in the presence of any single-site impurity.

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