Nontrivial interface states confined between two topological insulators

Rauch, Tomáš; Flieger, Markus; Henk, Jürgen; Mertig, Ingrid

doi:10.1103/physrevb.88.245120

Cited by 19 publications

(25 citation statements)

References 42 publications

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“…Recently it was demonstrated that in the Bi 2 Te 3 /SnTe heterostructure, the system containing Z 2 and crystal-mirrorsymmetry TIs, the¯ Dirac surface states of Bi 2 Te 3 and SnTe annihilate at the interface while the Dirac state of SnTe at theM "survives" [17]. This points out that the interaction of Z 2 TI and TCI systems can results in unusual changes in the topological surface state picture.…”

Section: Introductionmentioning

confidence: 99%

Sublattice effect on topological surface states in complex(SnTe)n>1(Bi2Te3)m

et al. 2015

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An exotic type of topological spin-helical surface state was found in layered van der Waals bonded (SnTe) n=2,3 (Bi 2 Te 3 ) m=1 compounds which comprise two covalently bonded band inverted sublattices, SnTe and Bi 2 Te 3 , within a building block. This topological state demonstrates unusual dispersion within the band gap. The dispersion of the surface state has two linear sections of different slope with a shoulder feature between them. Such a dispersion of the topological surface state enables an effective switch of the velocity of topological carriers by means of applying an external electric field.

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Section: Introductionmentioning

confidence: 99%

Sublattice effect on topological surface states in complex(SnTe)n>1(Bi2Te3)m

et al. 2015

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“…27 Subsequently the first-principles electronic structures were mapped onto tight-binding Hamiltonians. 28,29 The resulting band structures were checked against our first-principles KorringaKohn-Rostoker 24,30 and QUANTUMESPRESSO results and yield fine agreement, in particular for the energy range near the fundamental band gap.The electronic structures serves as an input to obtain the thermoelectric transport properties, using the layer-resolved transport distribution func-v ν k k k denotes the group velocities in the directions of the hexagonal basal plane and P i k k k is the layerresolved probability amplitude of a Bloch state, which allows for spatial decomposition of the transport properties. 32 Details on this projection technique are published elsewhere.…”

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confidence: 99%

Impact of the Topological Surface State on the Thermoelectric Transport in Sb₂Te₃ Thin Films

et al. 2015

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Ab initio electronic structure calculations based on density functional theory and tight-binding methods for the thermoelectric properties of ptype Sb 2 Te 3 films are presented. The thicknessdependent electrical conductivity and the thermopower are computed in the diffusive limit of transport based on the Boltzmann equation. Contributions of the bulk and the surface to the transport coefficients are separated which enables to identify a clear impact of the topological surface state on the thermoelectric properties. By tuning the charge carrier concentration, a crossover between a surface-state-dominant and a FuchsSondheimer transport regime is achieved. The calculations are corroborated by thermoelectric transport measurements on Sb 2 Te 3 films grown by atomic layer deposition.Almost all proposed three-dimensional (3D) Z 2 topological insulators (TIs) 1,2 are efficient thermoelectric materials. That is not by coincidence, since the link between an efficient thermoelectric * To whom correspondence should be addressed † Institute of Physics, Martin Luther University HalleWittenberg, D-06099 Halle, Germany ‡ Institute of Nanostructure and Solid State Physics, Universität Hamburg, Jungiusstrasse 11, D-20355 Hamburg, Germany ¶ Max Planck Institute of Microstructure Physics, Weinberg 2, D-06120 Halle, Germany material and the topological character is the inverted band gap. 3,4 The last is due to spin-orbit coupling which switches parity of the bands and leads, if strong enough, to narrow band gaps which are favourable for efficient room-temperature thermoelectrics. Usually strong spin-orbit coupling is mediated by heavy elements which in turn also tend to reduce the material's lattice thermal conductivity, another requirement for desirable thermoelectrics.In the early 90's, Hicks and Dresselhaus 5,6 proposed the concept of low-dimensionality to increase further the thermoelectric efficiency; primarily in thin films, the thermopower S should be enlarged. However, in contrast to previous theoretical model calculations, 7,8 decreased values of S were found experimentally 9-11 for Bi 2 Te 3 and Sb 2 Te 3 thin films and were recently corroborated by both model 12,13 and ab initio calculations 4 of our groups.Thus, to resolve this discrepancy, the potential impact of the surface state (SS) of TIs on thermoelectricity needs to be investigated in more detail. In this Letter, we present ab initio calculations and transport measurements of the thermoelectric properties of Sb 2 Te 3 films at varying thickness, temperature and charge carrier concentration. (1/ cm)(g) Theoretical resultsIn the following, we discuss the doping-and temperature-dependent electrical conductivity and thermopower, as shown in Fig. 1, exemplary for a Sb 2 Te 3 film thickness of 18 quintuple-layer (QL), i.e. about 18 nm. A discussion of films with other thicknesses is given in the supplemental material. 14 The converged electronic structure results serve as input to obtain the thermoelectric transport properties at temperature T and fixed extri...

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“…17,[19][20][21][22] The characteristics of the gapless boundary states are linear dispersion in the bulk band gap, spin-texture, robustness against scattering by nonmagnetic impurities, and symmetry protection. Studies have demonstrated that the formation of heterostructures, [23][24][25][26] alloying, 20,27 and thickness engineering 28 have advantages for controlling the electronic properties of TIs. In addition, recent studies show that it is possible to observe novel properties in TI superlattices, such as both time-reversal and crystal symmetry protected surface states, 29,30 band structure tuning through a topological phase transition, 31 topologically nontrivial surface states in a magnetic-TI/TI superlattice, 32 and the realization of 3D Weyl semimetal phases. 33 To fully exploit TIs in future devices, a detailed exploration of TI heterostructures/superlattices is needed.…”

Section: Introductionmentioning

confidence: 99%

Spinodal Superlattices of Topological Insulators

et al. 2018

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Spinodal decomposition is proposed for stabilizing self-assembled interfaces between topological insulators (TIs) by combining layers of iso-structural and iso-valent TlBiX2 (X=S, Se, Te) materials. The composition range for gapless states is addressed concurrently to the study of thermodynamically driven boundaries.By tailoring composition, the TlBiS2-TlBiTe2 system might produce both spinodal superlattices and two dimensional eutectic microstructures, either concurrently or separately. The dimensions and topological nature of the metallic channels are determined by following the spatial distribution of the charge density and the spin-texture. The results validate the proof of concept for obtaining spontaneously forming two-dimensional TI-conducting channels embedded into three-dimensional insulating environments without any vacuum interfaces. Since spinodal decomposition is a controllable kinetic phenomenon, its leverage could become the long-sought enabler for effective TI technological deployment.arXiv:1803.06289v1 [cond-mat.mtrl-sci]

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Nontrivial interface states confined between two topological insulators

Cited by 19 publications

References 42 publications

Sublattice effect on topological surface states in complex(SnTe)n>1(Bi2Te3)m

Sublattice effect on topological surface states in complex(SnTe)n>1(Bi2Te3)m

Impact of the Topological Surface State on the Thermoelectric Transport in Sb₂Te₃ Thin Films

Spinodal Superlattices of Topological Insulators

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Nontrivial interface states confined between two topological insulators

Cited by 19 publications

References 42 publications

Sublattice effect on topological surface states in complex(SnTe)n>1(Bi2Te3)m

Sublattice effect on topological surface states in complex(SnTe)n>1(Bi2Te3)m

Impact of the Topological Surface State on the Thermoelectric Transport in Sb2Te3 Thin Films

Spinodal Superlattices of Topological Insulators

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Impact of the Topological Surface State on the Thermoelectric Transport in Sb₂Te₃ Thin Films