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Jenkins, Gregory S.; Sushkov, A. B.; Schmadel, D. C.; Kim, Myoung-Hwan; Brahlek, Matthew; Bansal, Namrata; Oh, Seongshik; Drew, H. D.

doi:10.1103/physrevb.86.235133

Cited by 16 publications

(10 citation statements)

References 38 publications

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“…This is consistent with the fact that the magnetic mass-gap on the Dirac point (reported to be 20–50 meV by scanning tunnel spectroscopy 20 21 ) is sufficiently large as compared with the energy range of this measurement. Note also that possible cyclotron resonance under magnetic field, which has been observed in previous magneto-optical studies on TIs 22 23 24 25 26 27 28 , is absent in the present measurement because of zero external magnetic field. Furthermore, the observed Faraday and Kerr rotation angles are quantitatively consistent with the estimated rotation angles at d.c. limit ( Fig.…”

Section: Resultssupporting

confidence: 51%

“…Furthermore, the recently developed magnetic modulation-doping in Cr: (Bi, Sb) 2 Te 3 thin film 17 can markedly widen the observable temperature region of QAH effect up to several Kelvin, making feasible the optical measurement of QAH state. So far the low-energy magneto-optical responses have been intensively studied 22 23 24 25 26 27 28 29 mostly for nonmagnetic TIs, in which the cyclotron resonances of the surface states as well as the bulk carriers are reported. However, an experimental demonstration of TME effect on QAH state remains elusive.…”

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confidence: 99%

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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: Resultssupporting

confidence: 51%

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confidence: 99%

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

et al. 2016

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“…Doping the system with magnetic impurities induces an exchange field acting on the TI surface state [25]. Experiments in Bi 2 Se 3 thin films indicate the existence of colossal Kerr [26] and Faraday [27] rotations in the THz regime when time-reversal symmetry is broken by a strong magnetic field perpendicular to the slab. The measured Kerr angle is an order of magnitude larger than that observed in high mobility GaAs heterostructures [28].…”

Section: Introductionmentioning

confidence: 99%

Optical properties of magnetically doped ultrathin topological insulator slabs

Lasia

Brey

2014

Phys. Rev. B

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Starting from a three-dimensional Hamiltonian, we study the optical properties of ultrathin topological insulator slabs for which the coupling between Dirac fermions on opposite surfaces results in two degenerated gapped hyperbolic bands. The gap is a threshold for the optical absorption and translates in a peak in the imaginary part of the optical conductivity. An exchange field applied perpendicular to the slab splits the degenerated hyperbolic bands and a double step structure comes out in the optical absorption, whereas a double peak structure appears in the imaginary part of the longitudinal optical conductivity. The exchange field breaks time-reversal symmetry and for exchange fields larger than the surfaces coupling gap, the zero frequency Hall conductivity is quantized to e 2 /h. This result implies large values of the Kerr rotation angle and a quantization of the Faraday angle. In ultrathin slabs, the absence of light multiple scattering and bulk conductivity makes the Kerr angle remain rather large in a wide range of frequencies.

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“…Unlike the multiple surface states in Bi1-xSbx, these materials possess the advantage of exhibiting only a single Dirac cone on their naturally cleaved [111] surfaces. Zhang, Liu, et al 2009;Chen et al 2009) As a result, they have become the workhorse materials of the field with many ARPES, Xia et al 2009;Chen et al 2009) STM, Okada et al 2011;Alpichshev et al 2012b;Zhang, Cheng, et al 2009) transport, Xiong et al 2012) and optical (Valdes Aguilar et al 2012;Wu, Brahlek et al 2013;Jenkins et al 2010;Jenkins et al 2012) studies.…”

Section: Ivb 2 Bi2se3 Bi2te3 Sb2te3: 2 Nd Generation Tismentioning

confidence: 99%

Colloquium: Topological band theory

2016

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The first-principles band theory paradigm has been a key player not only in the process of discovering new classes of topologically interesting materials, but also for identifying salient characteristics of topological states, enabling direct and sharpened confrontation between theory and experiment. We begin this review by discussing underpinnings of the topological band theory, which basically involves a layer of analysis and interpretation for assessing topological properties of band structures beyond the standard band theory construct. Methods for evaluating topological invariants are delineated, including crystals without inversion symmetry and interacting systems. The extent to which theoretically predicted properties and protections of topological states have been verified experimentally is discussed, including work on topological crystalline insulators, disorder/interaction driven topological insulators (TIs), topological superconductors, Weyl semimetal phases, and topological phase transitions. Successful strategies for new materials discovery process are outlined. A comprehensive survey of currently predicted 2D and 3D topological materials is provided. This includes binary, ternary and quaternary compounds, transition metal and f-electron materials, Weyl and 3D Dirac semimetals, complex oxides, organometallics, skutterudites and antiperovskites. Also included is the emerging area of 2D atomically thin films beyond graphene of various elements and their alloys, functional thin films, multilayer systems, and ultra-thin films of 3D TIs, all of which hold exciting promise of wide-ranging applications. We conclude by giving a perspective on research directions where further work will broadly benefit the topological materials field.

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Giant plateau in the terahertz Faraday angle in gated Bi2Se3

Cited by 16 publications

References 38 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

Optical properties of magnetically doped ultrathin topological insulator slabs

Colloquium: Topological band theory

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