All-optical band engineering of gapped Dirac materials

Kibis, O. V.; Dini, K.; Iorsh, I. V.; Shelykh, I. A.

doi:10.1103/physrevb.95.125401

Cited by 105 publications

(80 citation statements)

References 56 publications

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“…When A and B are different, the inversion symmetry is broken and a band gap at K and K ′ is opened ( figure 4(a)). Gapped graphene and monolayer transition metal dichalcogenides (TMDCs) are such materials, exhibiting a direct band gap at K and K ′ [19,[44][45][46][47][48][49]. Note that both material classes can be approximated by the same Hamiltonian (equation (2), [19]).…”

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confidence: 99%

Sub-cycle temporal evolution of light-induced electron dynamics in hexagonal 2D materials

et al. 2020

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Two-dimensional materials with hexagonal symmetry such as graphene and transition metal dichalcogenides are unique materials to study light-field-controlled electron dynamics inside of a solid. Around the K-point, the dispersion relation represents an ideal system to study intricately coupled intraband motion and interband (Landau-Zener) transitions driven by the optical field of phase-controlled few-cycle laser pulses. Based on the coupled nature of the intraband and interband processes, we have recently observed in graphene repeated coherent Landau-Zener transitions between valence and conduction band separated by around half an optical period of 1.3 fs (Higuchi et al Nature 550, 224 (2017)). Due to the low temporal symmetry of the applied laser pulse, a residual current density and a net electron polarization are formed. Here we show extended numerical data on the temporal evolution of the conduction band population of 2D materials with hexagonal symmetry during the light-matter interaction, yielding deep insights to attosecond-fast electron dynamics. In addition, we show that a residual ballistic current density is formed, which strongly increases when a band gap is introduced. Both, the sub-cycle electron dynamics and the resulting residual current are relevant for the fundamental understanding and future applications of strongly driven electrons in two-dimensional materials, including graphene or transition metal dichalcogenide monolayers.

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confidence: 99%

Sub-cycle temporal evolution of light-induced electron dynamics in hexagonal 2D materials

et al. 2020

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“…Applying the zero boundary condition, Ψ(0) = 0, to the eigenspinor (25), we arrive at the homogeneous system of four algebraic equations defining the constants C 1,2,3,4 . The secular equation of the system reads as…”

Section: Resultsmentioning

confidence: 99%

Optically induced topological states on the surface of mercury telluride

Kyriienko

Shelykh

2019

Phys. Rev. B

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We developed the theory which describes the Floquet engineering of surface electronic modes in bulk mercury telluride (HgTe) by a circularly polarized electromagnetic field. The analysis shows that the field results in appearance of the surface states which arise from the mixing of conduction and valence bands of HgTe. Their branches lie near the center of the Brillouin zone and have the Dirac dispersion characteristic for topological states. Besides them, the irradiation induces the gap between the conduction and valence bands of HgTe. Thus, the irradiation can turn mercury telluride into topological insulator from gapless semiconductor. It is demonstrated that the optically induced states differ substantially from the non-topological surface states existing in HgTe without irradiation. The structure of the found states is studied both analytically and numerically in the broad range of their parameters.

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“…For high-frequency electromagnetic fields the real processes of photon absorption or emission cannot occur because of the constraints imposed by the energy conservation. However, off-resonant light can affect the electron system via virtual processes, leading thus to the pronounced band-structure renormalization [55][56][57][58][59][60][61] . Meanwhile, almost no attention was paid to the idea of using high-frequency electromagnetic radiation to the finite-size systems despite its potential impact on the realization of all-optical control in topological systems.…”

Section: Introductionmentioning

confidence: 99%

Impact of high-frequency pumping on anomalous finite-size effects in three-dimensional topological insulators

2018

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Lowering of the thickness of a thin-film three-dimensional topological insulator down to a few nanometers results in the gap opening in the spectrum of topologically protected two-dimensional surface states. This phenomenon, which is referred to as the anomalous finite-size effect, originates from hybridization between the states propagating along the opposite boundaries. In this work, we consider a bismuth-based topological insulator and show how the coupling to an intense high-frequency linearly polarized pumping can further be used to manipulate the value of a gap. We address this effect within recently proposed Brillouin-Wigner perturbation theory that allows us to map a time-dependent problem into a stationary one. Our analysis reveals that both the gap and the components of the group velocity of the surface states can be tuned in a controllable fashion by adjusting the intensity of the driving field within an experimentally accessible range and demonstrate the effect of light-induced band inversion in the spectrum of the surface states for high enough values of the pump.

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All-optical band engineering of gapped Dirac materials

Cited by 105 publications

References 56 publications

Sub-cycle temporal evolution of light-induced electron dynamics in hexagonal 2D materials

Sub-cycle temporal evolution of light-induced electron dynamics in hexagonal 2D materials

Optically induced topological states on the surface of mercury telluride

Impact of high-frequency pumping on anomalous finite-size effects in three-dimensional topological insulators

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