Current Vortices in Aromatic Carbon Molecules

Stegmann, Thomas; Franco-Villafañe, J. A.; Ortiz, Yenni P.; Deffner, Michael; Herrmann, Carmen; Kuhl, Ulrich; Mortessagne, Fabrice; Leyvraz, F.; Seligman, T. H.

doi:10.26434/chemrxiv.8251076

Cited by 6 publications

(7 citation statements)

References 35 publications

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“…Finally, the number of sites needed to build systems that display the behaviors discussed in this paper fits well with the current capabilities of microwave experiments [24,25]. We believe our results can be observed in such platforms.…”

Section: Discussionsupporting

confidence: 81%

Spectra, eigenstates and transport properties of a $\mathcal{PT}$-symmetric ring

Ortega,

Benet,

Larralde

2021

Preprint

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We study, analytically and numerically, a simple PT -symmetric tight-binding ring with an onsite energy a at the gain and loss sites. We show that if a = 0, the system generically exhibits an unbroken PT -symmetric phase. We study the nature of the spectrum in terms of the singularities in the complex parameter space as well as the behavior of the eigenstates at large values of the gain and loss strength. We find that in addition to the usual exceptional points, there are "diabolical points", and inverse exceptional points at which complex eigenvalues reconvert into real eigenvalues. We also study the transport through the system. We calculate the total flux from the source to the drain, and how it splits along the branches of the ring. We find that while usually the density flows from the source to the drain, for certain eigenstates a stationary "backflow" of density from the drain to the source along one of the branches can occur. We also identify two types of singular eigenstates, i.e. states that do not depend on the strength of the gain and loss, and classify them in terms of their transport properties.

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Section: Discussionsupporting

confidence: 81%

Spectra, eigenstates and transport properties of a $\mathcal{PT}$-symmetric ring

Ortega,

Benet,

Larralde

2021

Preprint

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“…In order to obtain the transport properties of the nanoflakes, we resort to the Non-Equilibrium Green's Function (NEGF) method which, coupled to the tightbinding formalism, is well known as an excellent tool to study current flow and transport phenomena in nanostructures [15][16][17][18][19][20] . To use the NEGF method we need to attach to the nanostructure two or more leads, which are metallic contacts acting as reservoirs.…”

Section: B the Non-equilibrium Green's Function Methodsmentioning

confidence: 99%

“…The functions f s,d are Fermi distributions for the reservoirs. With this formalism, we obtain the transport properties by means of the transmission function17…”

mentioning

confidence: 99%

Current vortices in hexagonal graphene quantum dots

Gomes,

Moraes

2021

Preprint

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Newly synthesized nanostructures of graphene appear as a promising breeding ground for new technology. Therefore, it is important to identify the role played by the boundary conditions in their electronic features. In this contribution we use the non-equilibrium Green's function method coupled to tight-binding theory to calculate and compare the current patterns of hexagonal graphene quantum dots, with contacts placed at different edge locations. Our results reveal the formation of current vortices when the symmetry of the contact geometry is in conflict with the symmetries of the quantum dot. The presence of current vortices suggests the use of graphene quantum dots as nanomagnets or magnetic nanosensors.

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“…Furthermore, important examples without external control parameters occur naturally in chemistry, as can be seen in the electronic spectrum of long organic compounds based on hexagonal structures: cyclopolyacenes [19][20][21][22][23][24]. In recent times, these interesting structures have received considerable attention, spurred by the need for better electronic transport in large molecules with nanotechnological applications [25][26][27][28][29][30][31]. Promising results related to these highly-conducting complexes include organic [32] and inorganic [33] realizations.…”

Section: Figmentioning

confidence: 99%

Hidden duality and accidental degeneracy in cycloacene and Möbius cycloacene

Sadurní¹,

Leyvraz²,

Stegmann³

et al. 2020

Preprint

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The accidental degeneracy appearing in cycloacenes as triplets and quadruplets is explained with the concept of segmentation, introduced here with the aim of describing the effective disconnection of π orbitals on these organic compounds. For periodic systems with time reversal symmetry, the emergent nodal domains are shown to divide the atomic chains into simpler carbon structures analog to benzene rings, diallyl chains, anthracene (triacene) chains and tetramethyl-naphtalene skeletal forms. The common electronic levels of these segments are identified as members of degenerate multiplets of the global system. The peculiar degeneracy of Möbius cycloacene is also explained by segmentation. In the last part, it is shown that the multiplicity of energies for cycloacene can be foreseen by studying the continuous limit of the tight-binding model; the degeneracy conditions are put in terms of Chebyshev polynomials. The results obtained in this work have important consequences on the physics of electronic transport in organic wires, together with their artificial realizations.

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Current Vortices in Aromatic Carbon Molecules

Cited by 6 publications

References 35 publications

Spectra, eigenstates and transport properties of a $\mathcal{PT}$-symmetric ring

Spectra, eigenstates and transport properties of a $\mathcal{PT}$-symmetric ring

Current vortices in hexagonal graphene quantum dots

Hidden duality and accidental degeneracy in cycloacene and Möbius cycloacene

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