Surface Scattering via Bulk Continuum States in the 3D Topological Insulator<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mi>Bi</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:msub><mml:mi>Se</mml:mi><mml:mn>3</mml:mn></mml:msub></mml:math>

Kim, Sunghun; Ye, Mao; Kuroda, Kenta; Yamada, Y.; Krasovskii, E. E.; Chulkov, Eugene V.; Miyamoto, Koji; Nakatake, M.; Okuda, Takashi; Ueda, Y.; Shimada, Kenya; Namatame, H.; Takeuchi, Masaki; Kimura, Akio

doi:10.1103/physrevlett.107.056803

Cited by 110 publications

(85 citation statements)

References 23 publications

(52 reference statements)

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“…Both considerations are consistent with our experimental findings and those reported in Ref. 33 and explain why only q 3 is clearly visible at −300 meV. At such an energy, the above-mentioned pockets becomes ill defined, with bulk states showing a continuum along every direction.…”

supporting

confidence: 82%

“…However, the data presented in Ref. 33, although taken over a wide energy range, do not show any dispersion. Furthermore, these scattering events are claimed for energies down to −400 meV, i.e., far below the energy range where the surface state exists.…”

mentioning

confidence: 85%

“…In Ref. 33 features in the FT dI/dU maps oriented along the M direction were interpreted as direct evidence of scattering from surface into bulk states. However, the data presented in Ref.…”

mentioning

confidence: 99%

“…For triangular defects like those shown in Ref. 33 and usually found on TI surfaces, the FT corresponds to a flower-like shape, with arms pointing along the M direction. The length of each arm is inversely proportional to the spatial extension of the defects and amounts to approximately 3 nm −1 , a result that does not depend on energy.…”

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Visualizing spin-dependent bulk scattering and breakdown of the linear dispersion relation in Bi2Te3

et al. 2013

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We performed a scanning tunneling spectroscopy investigation of the electronic properties of the topological insulator Bi 2 Te 3 in the energy range between −200 and +700 meV with respect to the Fermi level. For unoccupied states, tunneling into topological surface states dominates. Analysis of Fourier-transformed (FT) dI/dU maps allowed us to obtain their energy dispersion relation and to visualize the breakdown of the linear dispersion relation typical of massless particles. For occupied states, no signature of scattering events involving surface states can be detected. FT dI/dU maps reveal in this case two scattering vectors pointing along the M and K directions. Both are identified with scattering events within bulk states. Interestingly, vectors pointing along K which correspond to bulk backscattering events have a length longer than the minimum distance necessary to match opposite pockets on a constant energy cut. Comparison with calculated spin-resolved constant-energy cuts shows that this is a direct consequence of the chiral spin texture present in bulk states when their energy and momentum are close to the resonances of the spin-polarized topological surface states. The recent discovery of topological insulators (TIs), a new class of materials insulating in the bulk but conducting on the surface, has opened a new route towards spintronic devices. 1-3Topological surface states of TIs are gapless and, contrary to the trivial surface states usually found at surfaces in metals and semiconductors, cannot be destroyed by the presence of defects and adsorbates as long as time-reversal symmetry is preserved. [4][5][6][7][8] Topological surface states are characterized by a linear energy-momentum dispersion relation, and their charge carriers can be described by a Dirac-like equation for massless particles rather than the Schrödinger equation.9 Consequently, their phase velocity is coincident with the group velocity, and carriers at different energies are all moving with same speed. Because of the Kramers degeneracy theorem, opposite spin directions are degenerate only at high-symmetry points of the surface Brillouin zone where both time-and space-reversal symmetry is preserved: the so-called Dirac points. Above and below these points the spin is perpendicularly locked to the momentum, resulting in a chiral spin texture, 10 spin currents intrinsically tied to charge currents, 11 and forbidden backscattering. 12,13 This results in an increased spin coherence time, an important quantity for spintronic devices in which the information is encoded by the spin degree of freedom.14 In addition to possible technological applications, their spin and electronic structures make these materials a platform to search for exotic phenomena like Majorana fermions 15 and magnetic monopoles. 16 However, to what extent the electronic structure of topological states resembles the one typical of massless particles has not been clearly experimentally addressed so far. The same holds true concerning the spin-related properties of thes...

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confidence: 82%

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confidence: 85%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Visualizing spin-dependent bulk scattering and breakdown of the linear dispersion relation in Bi2Te3

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“…Actually, the surface-to-bulk scattering has been directly observed by scanning tunneling microscopy. 12 A homologous series of pseudobinary compounds, nGeTemBi 2 Te 3 , was intensively studied in terms of its thermoelectric, galvanomagnetic, and thermomagnetic properties. [27][28][29][30] Among them, GeBi 2 Te 4 was theoretically proposed as a member of the 3D TIs.…”

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Observation of a highly spin-polarized topological surface state in GeBi2Te4

et al. 2012

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Spin polarization of a topological surface state for GeBi 2 Te 4 , the newly discovered three-dimensional topological insulator, has been studied by means of state-of-the-art spin-and angle-resolved photoemission spectroscopy. It has been revealed that the disorder in the crystal has a minor effect on the surface-state spin polarization, which is 70% near the Dirac point in the bulk energy gap region (∼180 meV). This finding promises not only to realize a highly spin-polarized surface-isolated transport but also to add functionality to its thermoelectric and thermomagnetic properties.

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Topological Insulators, Topological Dirac semimetals, Topological Crystalline Insulators, and Topological Kondo Insulators

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2015

Topological Insulators

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IntroductionTopological phases of matter differ from conventional materials in that the former feature a nontrivial topological invariant in their bulk electronic wavefunction space [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. The experimental discoveries of the two-dimensional (2D) integer and fractional quantum Hall (IQH and FQH) states [15][16][17][18][19] in the 1980s realized the first two topological phases of matter in nature. These 2D topological systems are insulators in the bulk because the Fermi level is located in the middle of two Landau levels. On the other hand, the edges of these 2D topological insulators (TIs) (IQH and FQH) feature chiral 1D metallic states, leading to remarkable quantized charge transport phenomena. The quantized transverse magneto-conductivity = ne 2 ∕h (where e is the electric charge and h is the Planck constant) can be probed by charge transport experiements, which also provides a measure of the topological invariant (the Chern number) n that characterizes these quantum Hall states [20,21]. In 2005, theoretical advances [22, 23] predicted a third type of 2D TI, the quantum spin Hall (QSH) insulator. Such a topological state is symmetry-protected. A QSH insulator can be viewed as two copies of quantum Hall systems that have magnetic fields in the opposite direction. Therefore, no external magnetic field is required for the QSH phase, and the pair of quantum-Hall-like edge modes are related by the time-reversal (TR) symmetry (Figure 4.1). In 2007, the QSH phase was experimentally demonstrated in the (Hg, Cd)Te quantum wells using charge transport by measuring a longitudinal conductance of about 2e 2 ∕h (two copies of quantum Hall currents) at millikelvin temperatures [24]. The topological number that describes the QSH phase is a Z 2 invariant (ν). The Z 2 invariant can only take two values, 0 or 1, where ν = 0(1) is topologically trivial (nontrivial).However, it is important to note that the 2D topological (IQH, FQH, and QSH) insulators are realized only at buried interfaces of ultraclean semiconductor

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Surface Scattering via Bulk Continuum States in the 3D Topological InsulatorBi2Se3

Cited by 110 publications

References 23 publications

Visualizing spin-dependent bulk scattering and breakdown of the linear dispersion relation in Bi2Te3

Visualizing spin-dependent bulk scattering and breakdown of the linear dispersion relation in Bi2Te3

Observation of a highly spin-polarized topological surface state in GeBi2Te4

Topological Insulators, Topological Dirac semimetals, Topological Crystalline Insulators, and Topological Kondo Insulators

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