Structure-Imposed Electronic Topology in Cove-Edged Graphene Nanoribbons

Arnold, Florian M.; Liu, Tsai-Jung; Kuc, Agnieszka; Heine, Thomas

doi:10.1103/physrevlett.129.216401

Cited by 9 publications

(10 citation statements)

References 28 publications

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“…Below that flat band, there is a gap of about 60 meV. In the fully relaxed system, the corrugation of the layers results in the formation of a Dirac cone at K close to the Fermi level [26]. This can also be seen as a parabola-like shape of the DOS, similar to graphene.…”

Section: Electronic Propertiesmentioning

confidence: 97%

“…This changes for θ → 60 • , where small and large stacking domains alternate, separated by bent solitons. Different symmetries cause this: in θ → 0 • , all stacking domains exhibit a local R M h stacking, while in θ → 60 • , the adjacent domains alternate between H h h and H X h stackings, as shown in figure S1 [8,15,26]. The H h h and H X h stackings differ in energy (2 meV uc −1 , see figure 2).…”

Section: Structural and Energetic Propertiesmentioning

confidence: 99%

“…This results in the stacking domains for θ → 0 • showing local R M h stacking, while for θ → 60 • they alternate between H h h and H X h . This makes the Rtype stacking domains energetically equivalent, while the H-type stacking domains have different stacking energy, resulting in a size difference between adjacent stacking domains for twist angles near 60 • (see figure S1) [26]. Local R h h (H M h ) stacking arrangements are present within the nodes for θ → 0…”

Section: Structural and Energetic Propertiesmentioning

confidence: 99%

“…The solitons are marked by blue rectangles in figure 1(b) and act as a network of domain walls, separating adjacent stacking domains and vanishing only at exactly 0 • or 60 • . The stacking domains form a superlattice with honeycomb (hcb) symmetry, while the centers of the solitons form a kagome (kgm) lattice [25,26]. As the final structural element, the so-called nodes are formed at the intersections of the solitons, marked with red circles in figure 1(b).…”

Section: Introductionmentioning

confidence: 99%

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Relaxation effects in twisted bilayer molybdenum disulfide: structure, stability, and electronic properties

et al. 2023

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Manipulating the interlayer twist angle is a powerful tool to tailor the properties of layered two-dimensional crystals. The twist angle has a determinant impact on these systems’ atomistic structure and electronic properties. This includes the corrugation of individual layers, formation of stacking domains and other structural elements, and electronic structure changes due to the atomic reconstruction and superlattice eﬀects. However, how these properties change with the twist angle, θ, is not yet well understood. Here, we monitor the change of twisted bilayer MoS2 characteristics as a function of θ. We identify distinct structural regimes, each with particular structural and electronic properties. We employ a hierarchical approach ranging from a reactive force ﬁeld through the density-functional-based tight-binding approach and density-functional theory. To obtain a comprehensive overview, we analyzed a large number of twisted bilayers with twist angles in the range of θ = 0.2° . . . 59.6°. Some systems include up to half a million atoms, making structure optimization and electronic property calculation challenging. For 13° ≤ θ ≤ 47°, the structure is well-described by a moiré regime composed of two rigidly twisted monolayers. At small twist angles (θ ≤ 3° and 57° ≤ θ), a domain-soliton regime evolves, where the structure contains large triangular stacking domains, separated by a network of strain solitons and short-ranged high-energy nodes. The corrugation of the layers and the emerging superlattice of solitons and stacking domains aﬀects the electronic structure. Emerging predominant characteristic features are Dirac cones at K and kagome bands. These features ﬂatten for θ approaching 0° and 60°. Our results show at which range of θ the characteristic features of the reconstruction, namely extended stacking domains, the soliton network, and superlattice, emerge and give rise to exciting electronics. We expect our ﬁndings also to be relevant for other twisted bilayer systems.

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Section: Electronic Propertiesmentioning

confidence: 97%

Section: Structural and Energetic Propertiesmentioning

confidence: 99%

Section: Structural and Energetic Propertiesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Relaxation effects in twisted bilayer molybdenum disulfide: structure, stability, and electronic properties

et al. 2023

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“…Graphene nanoribbons (GNRs)few-nanometer-wide strips of sp 2 -bonded carbon atomsare promising components for next-generation nanoscale electronics , because of their sizable energy gap, − superior charge transport, and facile integration into short-channel field-effect transistors. − GNRs can be fabricated in an atomically precise fashion, leading to a rich spectrum of edge geometries , and electronic phases. − Of particular interest are zigzag graphene nanoribbons (ZGNRs), owing to their magnetically ordered ground state − that can be engineered through charge doping, electric fields, , lattice deformations, , or chemical functionalization of the edges. − The combination of controllable π-electron magnetism with a long spin coherence time at room temperature , renders ZGNRs suitable building blocks for spin logic operations …”

mentioning

confidence: 99%

Dirac Half-Semimetallicity and Antiferromagnetism in Graphene Nanoribbon/Hexagonal Boron Nitride Heterojunctions

et al. 2023

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Half-metals have been envisioned as active components in spintronic devices by virtue of their completely spin-polarized electrical currents. Actual materials hosting half-metallic phases, however, remain scarce. Here, we predict that recently fabricated heterojunctions of zigzag nanoribbons embedded in two-dimensional hexagonal boron nitride are half-semimetallic, featuring fully spin-polarized Dirac points at the Fermi level. The half-semimetallicity originates from the transfer of charges from hexagonal boron nitride to the embedded graphene nanoribbon. These charges give rise to opposite energy shifts of the states residing at the two edges, while preserving their intrinsic antiferromagnetic exchange coupling. Upon doping, an antiferromagnetic-to-ferrimagnetic phase transition occurs in these heterojunctions, with the sign of the excess charge controlling the spatial localization of the net magnetic moments. Our findings demonstrate that such heterojunctions realize tunable one-dimensional conducting channels of spin-polarized Dirac fermions seamlessly integrated into a two-dimensional insulator, thus holding promise for the development of carbon-based spintronics.

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One-Dimensional Magnetic Conduction Channels across Zigzag Graphene Nanoribbon/Hexagonal Boron Nitride Heterojunctions

Pizzochero,

Tepliakov,

Lischner

et al. 2024

Nano Lett.

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We examine the electronic structure of recently fabricated inplane heterojunctions of zigzag graphene nanoribbons embedded in hexagonal boron nitride. We focus on hitherto unexplored interface configurations in which both edges of the nanoribbon are bonded to the same chemical species, either boron or nitrogen atoms. Using ab initio and mean-field Hubbard model calculations, we reveal the emergence of onedimensional magnetic conducting channels at these interfaces. These channels originate from the energy shift of the magnetic interface states that is induced by charge transfer between the nanoribbon and hexagonal boron nitride. We further address the response of these heterojunctions to external electric and magnetic fields, demonstrating the tunability of energy and spin splittings in the electronic structure. Our findings establish that zigzag graphene nanoribbon/hexagonal boron nitride heterojunctions are a suitable platform for exploring and engineering spin transport in the atomically thin limit, with potential applications in integrated spintronic devices.

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Structure-Imposed Electronic Topology in Cove-Edged Graphene Nanoribbons

Cited by 9 publications

References 28 publications

Relaxation effects in twisted bilayer molybdenum disulfide: structure, stability, and electronic properties

Relaxation effects in twisted bilayer molybdenum disulfide: structure, stability, and electronic properties

Dirac Half-Semimetallicity and Antiferromagnetism in Graphene Nanoribbon/Hexagonal Boron Nitride Heterojunctions

One-Dimensional Magnetic Conduction Channels across Zigzag Graphene Nanoribbon/Hexagonal Boron Nitride Heterojunctions

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