Conductance of gated junctions as a probe of topological interface states

Thareja, Eklavya; Vekhter, Ilya; Asmar, Mahmoud M.

doi:10.1103/physrevb.102.125308

Cited by 8 publications

(5 citation statements)

References 36 publications

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“…In all cases we consider we confirmed that the kink voltage and the period of oscillation are independent of the specific values of α, β, and E [25]. For finite interface scattering the peak transmission value is reduced, and the slope of G(V g ) changes slightly, but the extracted velocity values remain the same.…”

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confidence: 70%

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Conductance of gated junctions as a probe of topological interface states

Thareja,

Vekhter,

Asmar

2019

Preprint

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Energy dispersion and spin orientation of the protected states at interfaces between topological insulators (TIs) and non-topological materials depend on the charge redistribution, strain, and atomic displacement at the interface. Knowledge of these properties is essential for applications of topological compounds, but direct access to them in the interface geometry is difficult. We show that conductance of a gated double junction at the surface of a topological insulator exhibits oscillations and a quasi-linear decay as a function of gate voltage in different regimes. These give the values for the quasiparticle velocities along and normal to the junction in the interface region, and determine the symmetry of the topological interface states. The results are insensitive to the boundary conditions at the junction.where the sum is over all the spin components, i = x, y, z,

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confidence: 70%

“…Our proposal provides quantitative measure of the symmetrybreaking effects intrinsic to the interface. We also show that the results are robust with respect to the details of the junction scattering [24,25].…”

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confidence: 89%

Conductance of gated junctions as a probe of topological interface states

Thareja,

Vekhter,

Asmar

2019

Preprint

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“…Indeed, a consistent treatment of boundaries within graphene strain engineering remains lacking. Nevertheless, multiple deformation fields are uniquely determined by boundaries and by sharp strain profiles: as it is the case in semiconductor heterojunctions, effective theories based on envelope wave functions call for supplemental boundary conditions of the form ψ = Mψ to retain hermiticity, and for self-adjoint extensions to preserve currents [72][73][74][75]. M is a matrix containing microscopic details and symmetries, and ψ is the electron/hole wavefunction at the boundary.…”

Section: Low-energy Effective Models: Dirac Equation Withmentioning

confidence: 99%

Mechanical, electronic, optical, piezoelectric and ferroic properties of strained graphene and other strained monolayers and multilayers: an update

Naumis,

Herrera,

Poudel

et al. 2023

Rep. Prog. Phys.

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This is an update of a previous review on the subject \cite{Naumis_2017}. Experimental and theoretical advances for straining graphene and other metallic, insulating, ferroelectric, ferroelastic, ferromagnetic and multiferroic 2D materials have been considered. Specific topics of discussion include: (i) methods to induce valley and sublattice polarisation ($\mathbf{P}$) in graphene, (ii) time-dependent strain and its impact on graphene's electronic properties, (iii) the role of local and global strain on superconductivity and other highly correlated and/or topological phases of graphene, inducing polarisation $\mathbf{P}$ on hexagonal boron nitride monolayers {\it via} strain, (iv) measuring strain, and modifying through strain the optoelectronic properties of transition metal dichalcogenides, (v) ferroic 2D materials with intrinsic elastic ($\sigma$), electric ($\mathbf{P}$) and magnetic ($\mathbf{M}$) polarisation under strain, as well as incipient 2D multiferroics and (vi) moir'e bilayers exhibiting flat electronic bands and exotic quantum phase diagrams, and other bilayer or few-layer systems exhibiting ferroic orders tunable by rotations and shear strain. The review features the extremely recent experimental realizations of a tunable two-dimensional Quantum Spin Hall effect in germanene, of monoelemental 2D ferroelectric bismuth, and 2D multiferroic NiI$_2$. The document was structured for a discussion of effects taking place in monolayers first, followed by discussions concerning bilayers and few-layers, and it represents a fresh and up-to-date overview of exciting and newest developments on the fast-paced field of 2D materials.

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“…For any effective theory that uses an envelope wavefunction, as is the case of the Dirac equation for graphene, the matching requires a supplemental boundary condition of the form Ψ = M Ψ in order to retain the hermiticity and preserve currents. Here M is a matrix containing the microscopic details and the symmetries of the problem [59][60][61][62][63][64] . Since we consider the Kekulé-Y bond modulation as a perturbation within the same graphene sheet, no major misalignment is expected and thus for small ∆ we can consider M as unitary throughout this work.…”

Section: Scatteringmentioning

confidence: 99%

Kekulé-induced valley birefringence and skew scattering in graphene

Andrade

Carrillo-Bastos²,

Asmar³

et al. 2022

Phys. Rev. B

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In graphene, a Kekulé-Y bond texture modifies the electronic band structure generating two concentric Dirac cones with different Fermi velocities lying in the Γ-point in reciprocal space. The energy dispersion results in different group velocities for each isospin component at a given energy. This energy spectrum combined with the negative refraction index in p-n junctions, allows the emergence of an electronic analog of optical birefringence in graphene. We characterize the valley birefringence produced by a circularly symmetric Kekulé patterned and gated region using the scattering approach. We found caustics with two cusps separated in space by a distance dependent on the Kekulé interaction and that provides a measure of its strength. Then, at low carrier concentration we find a non-vanishing skew cross section, showing the asymmetry in the scattering of electrons around the axis of the incoming flux. This effect is associated with the appearance of the valley Hall effect as electrons with opposite valley polarization are deflected towards opposite directions.

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Conductance of gated junctions as a probe of topological interface states

Cited by 8 publications

References 36 publications

Conductance of gated junctions as a probe of topological interface states

Conductance of gated junctions as a probe of topological interface states

Mechanical, electronic, optical, piezoelectric and ferroic properties of strained graphene and other strained monolayers and multilayers: an update

Kekulé-induced valley birefringence and skew scattering in graphene

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