Ferromagnetism in armchair graphene nanoribbon heterostructures

Almeida, P. A.; Sousa, L. S.; Schmidt, T. M.; Martins, G. B.

doi:10.1103/physrevb.105.054416

Cited by 3 publications

(2 citation statements)

References 62 publications

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“…This will be the value used for all our calculations. Almeida et al [45], by the current authors, presents an explicit expression for the tight-binding Hamiltonian in reciprocal space for an N-AGNR(1,3) heterostructure. Finally, since all the Hamiltonians analyzed here have chiral symmetry, implying a density of states that is symmetric around zero-energy, all results shown are either symmetric or anti-symmetric around µ = 0 (see figures 2-8).…”

Section: Model and Thermoelectric Coefficientsmentioning

confidence: 99%

Thermoelectric transport properties of armchair graphene nanoribbon heterostructures

Almeida

Martins²

2022

J. Phys.: Condens. Matter

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In this paper, we numerically analyze the thermoelectric properties of recently synthesized graphene nanoribbon heterostructures that are obtained as extensions of pristine armchair graphene nanoribbons (AGNRs). After simulating their band structure through a nearest-neighbor tight-binding model, we use the Landauer formalism to calculate the necessary thermoelectric coefficients, with which we obtain the electrical conductance G, thermopower S, thermal conductance Ke, linear-response thermocurrent I_th=∆T = GS, and figure of merit ZT (using literature results for the phonon thermal conductance Kph), at room temperature. We then compare the results for the nanoribbon heterostructures with those for the pristine AGNR nanoribbons. The comparison shows that the metallic AGNRs become semiconducting (with much higher ZT values) after the inclusion of the extensions that transform them into heterostructures and that some heterostructures have higher values of ZT when compared to the semiconducting pristine AGNRs from which they have originated.

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Section: Model and Thermoelectric Coefficientsmentioning

confidence: 99%

Thermoelectric transport properties of armchair graphene nanoribbon heterostructures

Almeida

Martins²

2022

J. Phys.: Condens. Matter

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“…Such bands having zero or quasizero dispersion are interesting also since the quenched kinetic energy for the flat bands can induce ferromagnetism and superconductivity [14,15]. It is worthy to point out that the strong correlations in magic-angle twisted bilayer graphene [16] are attributed to the flat minibands generated by the hexagonal Moiré superlattice [17,18].…”

Section: Introductionmentioning

confidence: 99%

Role of symmetry in quantum blocking of Andreev reflection in graphene nanoribbons side-terminated by superconductors

Takagaki

2023

J. Phys.: Condens. Matter

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Andreev reflection can be forbidden by means of quantum interference when superconductors are attached at the side edges of graphene nanoribbons. The blocking is restricted to single-mode nanoribbons having symmetric zigzag edges and is destroyed by the application of a magnetic field. These characteristics are shown to be the effects of the wavefunction parity on the Andreev retro and specular reflections. Not only the mirror symmetry of the graphene nanoribbons but also symmetric coupling of the superconductors is required for the quantum blocking. The quasi-flat-band states around the Dirac point energy induced for armchair nanoribbons by adding carbon atoms at the nanoribbon edges do not cause the quantum blocking due to the lack of the mirror symmetry. Furthermore, the phase modulation by the superconductors is shown to be able to convert the quasi-flat dispersion for the edge states of zigzag nanoribbons to a quasi-vertical dispersion.

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Quantum impurity with 23 local moment in one-dimensional quantum wires: A numerical renormalization group study

Almeida,

Manya,

Figueira

et al. 2024

Phys. Rev. B

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Ferromagnetism in armchair graphene nanoribbon heterostructures

Cited by 3 publications

References 62 publications

Thermoelectric transport properties of armchair graphene nanoribbon heterostructures

Thermoelectric transport properties of armchair graphene nanoribbon heterostructures

Role of symmetry in quantum blocking of Andreev reflection in graphene nanoribbons side-terminated by superconductors

Quantum impurity with 23 local moment in one-dimensional quantum wires: A numerical renormalization group study

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