Spin-split electronic states in graphene: Effects due to lattice deformation, Rashba effect, and adatoms by first principles

Abdelouahed, Samir; Ernst, A.; Henk, J.; Maznichenko, I. V.; Mertig, Ingrid

doi:10.1103/physrevb.82.125424

Cited by 118 publications

(143 citation statements)

References 39 publications

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“…(8) when choosing s = −1 and V 0 = 2E F in Eq. (10). Note that in the case of |E F − V 0 | < |E F |, the Fermi wave vector in the outgoing region is shorter than that in the incoming region, and an additional constraint for φ has to be applied to ensure…”

Section: Klein Tunneling In Mlg: Sharp Vs Smooth Interfacementioning

confidence: 99%

“…The latter is induced by the electric field perpendicular to the graphene plane, which can be externally controlled, and resembles the Rashba model 12,13 for the two-dimensional electron gas. Agreement has been achieved, based on first-principles calculations, 9,10 that the intrinsic SOC term opens a gap of the order of 2λ I ≈ 24 μeV, while the Rashba SOC removes the spin degeneracy and creates a spin-splitting 2λ R at the K and K points that has a linear dependence on an external electric field E with the slope of about 100 μeV per V/Å of E. Under a strong gate voltage, the Rashba coupling may in principle dominate the intrinsic SOC in MLG. 9,10 The low-energy spectrum of MLG plus the Rashba coupling (MLG + R) was derived by Rashba, 14 based on the Kane-Mele model 7 (i.e., an effective Dirac Hamiltonian).…”

Section: Introductionmentioning

confidence: 99%

“…Agreement has been achieved, based on first-principles calculations, 9,10 that the intrinsic SOC term opens a gap of the order of 2λ I ≈ 24 μeV, while the Rashba SOC removes the spin degeneracy and creates a spin-splitting 2λ R at the K and K points that has a linear dependence on an external electric field E with the slope of about 100 μeV per V/Å of E. Under a strong gate voltage, the Rashba coupling may in principle dominate the intrinsic SOC in MLG. 9,10 The low-energy spectrum of MLG plus the Rashba coupling (MLG + R) was derived by Rashba, 14 based on the Kane-Mele model 7 (i.e., an effective Dirac Hamiltonian). An earlier work by one of us 15 started with a tight-binding model (TBM) and obtained an equivalent form of the low-energy expansion, 16 E MLG+R (q) ≈ μ 1 2 [ (3t R ) 2 + (3ta · q) 2 + ν(3t R )], (1) which also agrees with expressions given in Refs.…”

Section: Introductionmentioning

confidence: 99%

“…6 The question about the role of SOC effects in graphene then naturally emerged, including the proposal of graphene as a topological insulator, 7 which attracted the attention of various first-principles-based studies. [8][9][10] SOC in MLG includes an intrinsic and an extrinsic term. The former reflects the inherent asymmetry of electron hopping between next nearest neighbors 7 (i.e., a generalization of Haldane's model 11 ).…”

Section: Introductionmentioning

confidence: 99%

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Spin-dependent Klein tunneling in graphene: Role of Rashba spin-orbit coupling

2012

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Within an effective Dirac theory the low-energy dispersions of monolayer graphene in the presence of Rashba spin-orbit coupling and spin-degenerate bilayer graphene are described by formally identical expressions. We explore implications of this correspondence for transport by choosing chiral tunneling through pn and pnp junctions as a concrete example. A real-space Green's function formalism based on a tight-binding model is adopted to perform the ballistic transport calculations, which cover and confirm previous theoretical results based on the Dirac theory. Chiral tunneling in monolayer graphene in the presence of Rashba coupling is shown to indeed behave like in bilayer graphene. Combined effects of a forbidden normal transmission and spin separation are observed within the single-band n ↔ p transmission regime. The former comes from real-spin conservation, in analogy with pseudospin conservation in bilayer graphene, while the latter arises from the intrinsic spin-Hall mechanism of the Rashba coupling.

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Section: Klein Tunneling In Mlg: Sharp Vs Smooth Interfacementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Spin-dependent Klein tunneling in graphene: Role of Rashba spin-orbit coupling

2012

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“…8,9 More recently, several groups have demonstrated theoretically by depositing the adatoms of heavy elements with large magnitudes of atomic spin-orbit splitting it is possible to increase the spin-orbit gap up to tens meV. [10][11][12][13] However, realizing such this strategy in practice will inevitably face the challenge of uniform deposition since adatoms are mobile 14,15 and tend to form aggregates due to attractive interactions.…”

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confidence: 99%

Engineering quantum spin Hall effect in graphene nanoribbons via edge functionalization

Autès

Yazyev

2013

Phys. Rev. B

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Kane and Mele predicted that in presence of spin-orbit interaction graphene realizes the quantum spin Hall state. However, exceptionally weak intrinsic spin-orbit splitting in graphene (≈ 10 −5 eV) inhibits experimental observation of this topological insulating phase. To circumvent this problem, we propose a novel approach towards controlling spin-orbit interactions in graphene by means of covalent functionalization of graphene edges with functional groups containing heavy elements. Proof-of-concept first-principles calculations show that very strong spin-orbit coupling can be induced in realistic models of narrow graphene nanoribbons with telluriumterminated edges. We demonstrate that electronic bands with strong Rashba splitting as well as the quantum spin Hall state spanning broad energy ranges can be realized in such systems. Our work thus opens up new horizons towards engineering topological electronic phases in nanostructures based on graphene and other materials by means of locally introduced spin-orbit interactions.

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A Perspective on Recent Advances in 2D Stanene Nanosheets

Sahoo

Wei

2019

Adv Materials Inter

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for example, incompatibility with the semiconductor industry, [13] toxicity, [14] and susceptibility to oxidative environments. [7] Accordingly, researchers are on the lookout for other existing or synthetic 2D analogues.There have been numerous reports describing a wide variety of layered ultrathin 2D nanomaterials beyond graphene, with fascinating and technologydriven properties. These single-layer atomic crystals are classified in terms of their constituent elemental bonding states and structures. Most of them are transition metals bonded with chalcogenide groups (e.g., MoS 2 , MoSe 2 , WS 2 , TiS 2 ), [13,15] metal carbides and nitrides (MXenes), [16] metalorganic frameworks (MOFs), [17] covalent organic frameworks (COFs), [18] hexagonal boron nitrides, [19] and monoelemental 2D analogues (e.g., silicene, germanene, and phosphorene). [20] The emergence of new fascinating physical and chemical properties is encouraging the discovery of new classes of 2D nanomaterials, prepared either from 3D van der Waals bulk phases (through top-down techniques) or through self-assembly of elemental constituents from wet-chemical or vapor phase (bottom-up approaches). The former types of synthetic strategies are mostly exfoliation processes from 3D layered structures, including physical exfoliation (by forced delamination of layers), [21] liquid phase exfoliation (by the chemistry of matching with solute-solvent interface energy), [22] and ion intercalation and exfoliation (by electrochemical reactions). [23,24] These processes for preparing 2D nanosheets are widely followed because they are sufficiently simple and robust for scalable production; nevertheless, they can be challenging to use when synthesizing nanosheets with uniform thicknesses and lateral dimensions. The scalability of these processes for manufacturing nanosheets has, however, been exploited widely, for example, in energy storage devices, [25] sensors, [26] electronics and photonic devices, [27] as well as in biomedicine. [27] The bottom-up approaches involve growth and self-assembly from the atomic scale, mostly involving chemical vapor deposition, [28] pulsed laser deposition, [28] and epitaxial growth. [29] Although these processes for fabricating 2D nanosheets provide good control over the homogeneity of the structures, they occur with complex growth mechanisms and are not scalable. Interestingly, quantum confinement effects are prominent in fabricated atomic-layer structures, and suggest a new dimension for future nanoelectronics and many other advanced applications. [30][31][32][33] Advancements in 2D nanomaterials have been impacting a wide range of technology-driven applications. Here, the authors highlight stanene, a material that comprises a monolayer of elemental tin atoms, as a new addition to the monoelemental 2D family. Recent successes in the experimental realization of stanene in supported heterostructures and in free-standing form have expanded interest in exploring and unlocking its potential applications, as predicted from advanced theoreti...

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Spin-split electronic states in graphene: Effects due to lattice deformation, Rashba effect, and adatoms by first principles

Cited by 118 publications

References 39 publications

Spin-dependent Klein tunneling in graphene: Role of Rashba spin-orbit coupling

Spin-dependent Klein tunneling in graphene: Role of Rashba spin-orbit coupling

Engineering quantum spin Hall effect in graphene nanoribbons via edge functionalization

A Perspective on Recent Advances in 2D Stanene Nanosheets

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