Spin splitting and spin Hall conductivity in buckled monolayers of group 14: First-principles calculations

Farzaneh, S. M.; Rakheja, Shaloo

doi:10.1103/physrevb.104.115205

Cited by 8 publications

(5 citation statements)

References 64 publications

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“…[65][66][67] for quantum point contacts). Other intriguing future directions would be to study the details of the tunnel-coupling between a TI edge and a ferromagnetic contact [68][69][70][71] or the effects of electric fields in relatively clean systems and investigate the potential to control spin polarization electrically [72]. Finally, we note that a similar analysis using an incoming left-mover gives the same coefficients, resulting in a unitary scattering matrix as given by Eq.…”

Section: Discussionmentioning

confidence: 92%

Edge spin transport in the disordered two-dimensional topological insulator WTe$_2$

Copenhaver,

Väyrynen

2021

Preprint

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The spin conductance of two-dimensional topological insulators (2D TIs) is not expected to be quantized in the presence of perturbations that break the spin-rotational symmetry. However, the deviation from the pristine-limit quantization has yet to be studied in detail. In this paper, we define the spin current operator for the helical edge modes of a 2D TI and introduce a four-terminal setup to measure spin conductances. Using the developed formalism, we consider the effects of disorder terms that break spin-rotational symmetry or give rise to edge-to-edge coupling. We identify a key role played by spin torque in an out-of-equilibrium edge. We then utilize a tight-binding model of topological monolayer WTe2 and scattering matrix formalism to numerically study spin transport in a four-terminal 2D TI device. In particular, we calculate the spin conductances and characteristic spin decay length in the presence of magnetic disorder. In addition, we study the effects of interedge scattering in a quantum point contact geometry. We find that the spin Hall conductance is surprisingly robust to spin symmetry-breaking perturbations, as long as time-reversal symmetry is preserved and inter-edge scattering is weak.

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Section: Discussionmentioning

confidence: 92%

Edge spin transport in the disordered two-dimensional topological insulator WTe$_2$

Copenhaver,

Väyrynen

2021

Preprint

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“…Furthermore, silicene is ambipolar, in which charge carriers behave as massless Dirac fermions in which π and π * bands touch linearly at the Fermi level and have Dirac points at K and K ′ points of the Brillouin zone. In contrast to the flat honeycomb lattice of graphene, the molecular dynamics and first-principles calculations show that the honeycomb lattice of silicene is not flat and has a stable buckled structure [10][11][12][13][14][15][16][17][18]. The similarities and dissimilarities between silicene and graphene are listed in table 1.…”

Section: Introductionmentioning

confidence: 99%

Flexural and acoustic phonon-drag thermopower and electron energy loss rate in silicene

Ansari,

Ashraf,

Tripathi

et al. 2024

J. Phys.: Condens. Matter

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We have performed a comprehensive numerical and analytical examination of two crucial transport aspects in silicene: the phonon-drag thermopower,S^p,and the electron's energy loss rate,F_e. Specifically, our investigation is centered on their responses to out-of-plane flexural phonons and in-plane acoustic phonons in silicene, a two-dimensional allotrope of silicon as a function of electron temperature, T, and electron concentration, n, upto the room temperature. It is found that the calculated quantities have a non-monotonic dependence for the phonon modes for both parameters (T and n) considered while analytical results predict definite dependencies up to the complete low-temperature Bloch-Gruneisen (BG) regime. To provide a more comprehensive picture, we contrast the complete numerical outcomes with the approximated analytical BG results, revealing a convergence within a specific range of temperature and carrier concentration. In light of this convergence, we put forth suggestions to elucidate the underlying factors responsible for this behavior. A comparison based on the magnitude of the calculated quantities can be made from the figures between the two considered phonon modes, which clearly shows that the out-of-plane flexural phonons are effective throughout the considered temperature range. This observation leads us to posit that the dominating contribution of the out-of-plane flexural phonons modes hinges upon the deformation potential constant and phonon energy associated with the phonon mode. Our study carries significant implications for estimating the electrical and thermal properties of silicene and provides valuable insights for the development of devices based on silicene-based technologies.

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“…Also, in the buckled structures of stanene and silicene with hybridization sp 3 type [32], the hexagonal Brillouin zone (BZ) attributes a massless Dirac fermion character to the charge carriers. Other attempts were made to account for the effect of spin splitting in buckled monolayers of group-IV [33], and the effect of an electric field of GaAs monolayer [34] from first-principles calculations. They also sought a robust large gap 2D TIs in hydrogenated III-V buckled systems [35].…”

Section: Introductionmentioning

confidence: 99%

Topological viewpoint of two-dimensional group III–V and IV–IV compounds in the presence of electric field and spin–orbit coupling by density functional theory and tight-binding model

Baradaran

Ghaffarian

2022

J. Phys.: Condens. Matter

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Using the tight-binding model and density functional theory, the topological invariant of the two-dimensional (2D) group III-V and IV-IV compounds are studied in the absence and the presence of an external perpendicular electric field and spin-orbit coupling. It will be recognized that a critical value of these parameters changes the topological invariant of 2D graphene-like compounds. The significant effects of an external electric field and spin-orbit coupling are considered to the two-center overlap integrals of the Slater-Koster model involved in band structures, changing band-gap, and tuning the topological phase transition between ordinary and quantum spin Hall regime. These declare the good consistency between two theories: tight-binding and density functional. So, this study reveals topological phase transition in these materials. Our finding paves a way to extend an effective Hamiltonian, and may instantly clear some computation aspects of the study in the field of spintronic based on the first-principles methods.

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Spin splitting and spin Hall conductivity in buckled monolayers of group 14: First-principles calculations

Cited by 8 publications

References 64 publications

Edge spin transport in the disordered two-dimensional topological insulator WTe$_2$

Edge spin transport in the disordered two-dimensional topological insulator WTe$_2$

Flexural and acoustic phonon-drag thermopower and electron energy loss rate in silicene

Topological viewpoint of two-dimensional group III–V and IV–IV compounds in the presence of electric field and spin–orbit coupling by density functional theory and tight-binding model

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