Sum-Rule Constraints on the Surface State Conductance of Topological Insulators

Post, Kirk; Chapler, B. C.; Liu, M. K.; Wu, James Swi‐Bea; Stinson, H. T.; Goldflam, Michael; Richardella, Anthony; Lee, Joon Sue; Reijnders, Anjan; Burch, Kenneth S.; Fogler, M. M.; Samarth, N.; Basov, D. N.

doi:10.1103/physrevlett.115.116804

Cited by 22 publications

(21 citation statements)

References 43 publications

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“…2a . The transmittance is close to unity, that is, no discernible absorption, except for the dips around 7 meV indicated by the arrow, which is assigned to the optical phonon mode 32 ; see also the optical conductance σ xx spectrum at T =4.3 K also shown in Fig. 2a .…”

Section: Resultsmentioning

confidence: 69%

Terahertz spectroscopy on Faraday and Kerr rotations in a quantum anomalous Hall state

et al. 2016

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Electrodynamic responses from three-dimensional topological insulators are characterized by the universal magnetoelectric term constituent of the Lagrangian formalism. The quantized magnetoelectric coupling, which is generally referred to as topological magnetoelectric effect, has been predicted to induce exotic phenomena including the universal low-energy magneto-optical effects. Here we report the experimental indication of the topological magnetoelectric effect, which is exemplified by magneto-optical Faraday and Kerr rotations in the quantum anomalous Hall states of magnetic topological insulator surfaces by terahertz magneto-optics. The universal relation composed of the observed Faraday and Kerr rotation angles but not of any material parameters (for example, dielectric constant and magnetic susceptibility) well exhibits the trajectory towards the fine structure constant in the quantized limit.

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Section: Resultsmentioning

confidence: 69%

Terahertz spectroscopy on Faraday and Kerr rotations in a quantum anomalous Hall state

et al. 2016

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“…We speculate that this peak may be due to a defect state or subband, and add that it persists in room temperature measurements and is thus unlikely to be excitonic in nature. 12,[43][44][45] In conclusion, we have experimentally investigated the mid-infrared optical response of…”

Section: Discussionmentioning

confidence: 99%

Gate-Variable Mid-Infrared Optical Transitions in a (Bi_1–xSb_x)₂Te₃ Topological Insulator

Whitney

Brar

et al. 2016

Nano Lett.

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We report mid-infrared spectroscopy measurements of ultrathin, electrostatically gated (BiSb)Te topological insulator films in which we observe several percent modulation of transmittance and reflectance as gating shifts the Fermi level. Infrared transmittance measurements of gated films were enabled by use of an epitaxial lift-off method for large-area transfer of topological insulator films from infrared-absorbing SrTiO growth substrates to thermal oxidized silicon substrates. We combine these optical experiments with transport measurements and angle-resolved photoemission spectroscopy to identify the observed spectral modulation as a gate-driven transfer of spectral weight between both bulk and 2D topological surface channels and interband and intraband channels. We develop a model for the complex permittivity of gated (BiSb)Te and find a good match to our experimental data. These results open the path for layered topological insulator materials as a new candidate for tunable, ultrathin infrared optics and highlight the possibility of switching topological optoelectronic phenomena between bulk and spin-polarized surface regimes.

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“…There have been a number of experimental works which investigated the optical response and plasmonic resonances of bulk topological insulators [14][15][16][17][18][19][20][21][22][23][24][25][26] and new theoretical phenomena were predicted. [27][28][29][30] Also, plasmons in topological nano particles have been dealt with.…”

Section: Introductionmentioning

confidence: 99%

Plasmonics in Topological Insulators: Spin–Charge Separation, the Influence of the Inversion Layer, and Phonon–Plasmon Coupling

2017

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We demonstrate via three examples that topological insulators (TI) offer a new platform for plasmonics. First, we show that the collective excitations of a thin slab of a TI display spin-charge separation. This gives rise to purely charge-like optical and purely spin-like acoustic plasmons, respectively. Second, we argue that the depletion layer mixes Dirac and Schrödinger electrons which can lead to novel features such as high modulation depths and interband plasmons. The analysis is based on an extension of the usual formula for optical plasmons that depends on the slab width and on the dielectric constant of the TI. Third, we discuss the coupling of the TI surface phonons to the plasmons and find strong hybridisation especially for samples with large slab widths. arXiv:1706.09403v2 [cond-mat.mes-hall]

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Sum-Rule Constraints on the Surface State Conductance of Topological Insulators

Cited by 22 publications

References 43 publications

Terahertz spectroscopy on Faraday and Kerr rotations in a quantum anomalous Hall state

Terahertz spectroscopy on Faraday and Kerr rotations in a quantum anomalous Hall state

Gate-Variable Mid-Infrared Optical Transitions in a (Bi_1–xSb_x)₂Te₃ Topological Insulator

Plasmonics in Topological Insulators: Spin–Charge Separation, the Influence of the Inversion Layer, and Phonon–Plasmon Coupling

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Sum-Rule Constraints on the Surface State Conductance of Topological Insulators

Cited by 22 publications

References 43 publications

Terahertz spectroscopy on Faraday and Kerr rotations in a quantum anomalous Hall state

Terahertz spectroscopy on Faraday and Kerr rotations in a quantum anomalous Hall state

Gate-Variable Mid-Infrared Optical Transitions in a (Bi1–xSbx)2Te3 Topological Insulator

Plasmonics in Topological Insulators: Spin–Charge Separation, the Influence of the Inversion Layer, and Phonon–Plasmon Coupling

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Gate-Variable Mid-Infrared Optical Transitions in a (Bi_1–xSb_x)₂Te₃ Topological Insulator