Multiple Dirac fermions from a topological insulator and graphene superlattice

Jin, Hosub; Im, Jino; Song, Jung Hwan; Freeman, Arthur J

doi:10.1103/physrevb.85.045307

Cited by 13 publications

(9 citation statements)

References 29 publications

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“…Such nano-structures can be experimentally implemented to control both spectrum and transport properties of Dirac electrons in graphene. Similar kind of structures have been proposed and made in TIs [10][11][12][13] .…”

Section: Introductionmentioning

confidence: 84%

Dirac fermion time-Floquet crystal: Manipulating Dirac points

Rodriguez-López¹,

Betouras²,

Savel’ev³

2014

Phys. Rev. B

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We demonstrate how to control the spectra and current flow of Dirac electrons in both a graphene sheet and a topological insulator by applying either two linearly polarized laser fields with frequencies ω and 2ω or a monochromatic (one-frequency) laser field together with a spatially periodic static potential (graphene/TI superlattice). Using the Floquet theory and the resonance approximation, we show that a Dirac point in the electron spectrum can be split into several Dirac points whose relative location in momentum space can be efficiently manipulated by changing the characteristics of the laser fields. In addition, the laser-field controlled Dirac fermion band structure -Dirac fermion time-Floquet crystal -allows the manipulation of the electron currents in graphene and topological insulators. Furthermore, the generation of dc currents of desirable intensity in a chosen direction occurs when applying the bi-harmonic laser field which can provide a straightforward experimental test of the predicted phenomena.

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Section: Introductionmentioning

confidence: 84%

Dirac fermion time-Floquet crystal: Manipulating Dirac points

Rodriguez-López¹,

Betouras²,

Savel’ev³

2014

Phys. Rev. B

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“…Common strategies for achieving such a control involve chemical substitution and adsorbate doping [9][10][11][12][13]. Alternatively, it has been proposed that multilayer heterostructures could be used to obtain artificial TIs with tunable properties defined by the stacking sequences of the constituent two-dimensional building blocks [14][15][16].In this Rapid Communication, we demonstrate the possibility of TSS band-structure engineering in the naturally occurring homologous series of topological superlattices (Sb 2 ) m -(Sb 2 Te 3 ) n composed of Sb 2 bilayers (BLs) and Sb 2 Te 3 quintuple layers (QLs) [17,18]. This series enables a systematic investigation of the evolution of topological properties as a function of the stacking sequence of the constituent building blocks.…”

mentioning

confidence: 99%

mentioning

confidence: 99%

Engineering the topological surface states in the(Sb2)m−Sb2Te3(m=0
Johannsen
¹
,
Autès
²
,
Crepaldi
³

et al. 2015
Phys. Rev. B
19
1
20
0
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We investigate the evolution of both the occupied and unoccupied electronic structure in representative compounds of the infinitely adaptive superlattice series (Sb 2 ) m -Sb 2 Te 3 (m = 0-3) by means of angle-resolved photoemission spectroscopy and time-delayed two-photon photoemission, combined with first-principles band-structure calculations. We discover that the topological nature of the surface states and their spin texture are robust, with dispersions evolving from linear (Dirac-like) to parabolic (Rashba-like) along the series, as the materials evolve from semiconductors to semimetals. Our findings provide a promising strategy for engineering the topological states with the desired flexibility needed for realizing different quantum phenomena and spintronics applications. Three-dimensional topological insulators (TIs) are materials where the topological properties of the insulating bulk band structure guarantee the existence of metallic surface states [1,2]. These topological surface states (TSS) are characterized by a Dirac-like energy-momentum dispersion and by a helical spin-momentum texture [3,4] that protects them against backscattering and localization [5,6]. TIs are promising materials for spintronics and provide an exceptional playground to study novel physical phenomena [7,8]. Possible applications depend on the ability to control the electronic properties of the TSS. Common strategies for achieving such a control involve chemical substitution and adsorbate doping [9][10][11][12][13]. Alternatively, it has been proposed that multilayer heterostructures could be used to obtain artificial TIs with tunable properties defined by the stacking sequences of the constituent two-dimensional building blocks [14][15][16].In this Rapid Communication, we demonstrate the possibility of TSS band-structure engineering in the naturally occurring homologous series of topological superlattices (Sb 2 ) m -(Sb 2 Te 3 ) n composed of Sb 2 bilayers (BLs) and Sb 2 Te 3 quintuple layers (QLs) [17,18]. This series enables a systematic investigation of the evolution of topological properties as a function of the stacking sequence of the constituent building blocks. Our results show that the topological states are remarkably robust and that their dispersion can be tuned in the explored range (m = 0-3; n = 1), and in bulk Sb, with an unchanging strong Z 2 index ν 0 = 1.All (Sb 2 ) m -(Sb 2 Te 3 ) n compounds display layered crystal structures produced by ordered stacking of Sb 2 Te 3 QLs and antimony BLs along the c axis of the hexagonal unit cell. This provides for an "infinitely adaptive series" of * marco.grioni@epfl.ch distinct compounds between the end member compositions Sb 2 Te 3 (m = 0) and Sb (n = 0) [17][18][19][20] that are known to be a TI and a topological semimetal, respectively [21][22][23][24][25][26][27]. Early experiments assessed the topological nature of bulk Sb and Sb-Bi alloys [21,22]. By contrast, the experimental observation of the predicted TSS in Sb 2 Te 3 has been delayed by the intrinsic p doping ...

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“…13 In addition, several theoretical studies have predicted that novel properties may emerge when topological insulators are interlaced with other materials in a regular superlattice. 14,15 In order to pursue these promising avenues, however, various experimental challenges have to be solved. For example, a basic understanding of the surface band structures of more complex topological materials, while highly desirable, is not trivial.…”

mentioning

confidence: 99%

Termination-dependent topological surface states of the natural superlattice phase Bi4Se3

et al. 2013

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We describe the topological surface states of Bi 4 Se 3 , a compound in the infinitely adaptive Bi 2 -Bi 2 Se 3 natural superlattice phase series, determined by a combination of experimental and theoretical methods. Two observable cleavage surfaces, terminating at Bi or Se, are characterized by angle-resolved photoelectron spectroscopy and scanning tunneling microscopy, and modeled by ab initio density functional theory calculations. Topological surface states are observed on both surfaces, but with markedly different dispersions and Kramers point energies. Three-dimensional topological insulators (3D TIs) are a new class of materials that exhibit topologically protected helical metallic topological surface states (TSS) and a bulk band gap. [1][2][3][4][5][6][7][8][9][10][11][12] The great interest in 3D TIs is partly due to the fact that they necessarily host exotic bound states at their boundaries when interfaced with other nontopological or topological materials. 13 In addition, several theoretical studies have predicted that novel properties may emerge when topological insulators are interlaced with other materials in a regular superlattice. 14,15 In order to pursue these promising avenues, however, various experimental challenges have to be solved. For example, a basic understanding of the surface band structures of more complex topological materials, while highly desirable, is not trivial. Although there have been studies of different materials at the interface of 3D TIs, 16,17 and on different surface terminations of the same material, 18,19 no in-depth study of the TSS and electronic band structure of a complex topological material or a true bulk topological superlattice material has yet been reported.Here, we investigate the properties of Bi 4 Se 3 , the simplest topological superlattice material, consisting of single Bi 2 layers interleaved with single Bi 2 Se 3 layers in a 1:1 ratio 20 [ Fig. 1(a)]. While bulk Bi 2 Se 3 is a model 3D TI, an isolated Bi 2 layer is predicted to be a 2D TI; 21 combining these two building blocks into a 3D superlattice offers a unique possibility for studying the effects of interlayer interactions. We investigate the electronic structure of this material experimentally via angle-resolved photoemission spectroscopy (ARPES) and scanning tunneling microscopy (STM) and theoretically via ab initio density functional theory (DFT) calculations. We observe two types of surfaces after cleaving the crystal, corresponding to Bi 2 -and Bi 2 Se 3 -terminated terraces. We find that both terminations exhibit TSS, but with substantially different Kramers point energies and dispersions. We show that many features of the surface band structure can be derived from the idealized case of weakly coupled Bi 2 and Bi 2 Se 3 layers where the interaction between these building blocks is responsible for the different TSSs. Bi 4 Se 3 and related (Bi 2 ) m (Bi 2 Se 3 ) n (Ref. 22) superlattice phases provide a unique opportunity for studying the coexistence of multiple types of topological surface st...

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Multiple Dirac fermions from a topological insulator and graphene superlattice

Cited by 13 publications

References 29 publications

Dirac fermion time-Floquet crystal: Manipulating Dirac points

Dirac fermion time-Floquet crystal: Manipulating Dirac points

Engineering the topological surface states in the(Sb2)m−Sb2Te3(m=0
Johannsen
¹
,
Autès
²
,
Crepaldi
³

et al. 2015
Phys. Rev. B
19
1
20
0
View full text Add to dashboard Cite

Termination-dependent topological surface states of the natural superlattice phase Bi4Se3

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Multiple Dirac fermions from a topological insulator and graphene superlattice

Cited by 13 publications

References 29 publications

Dirac fermion time-Floquet crystal: Manipulating Dirac points

Dirac fermion time-Floquet crystal: Manipulating Dirac points

Engineering the topological surface states in the(Sb2)m−Sb2Te3(m=0Johannsen1, Autès2, Crepaldi3 et al. 2015Phys. Rev. B191200View full textAdd to dashboardCite

Termination-dependent topological surface states of the natural superlattice phase Bi4Se3

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Product

Resources

About

Engineering the topological surface states in the(Sb2)m−Sb2Te3(m=0
Johannsen
¹
,
Autès
²
,
Crepaldi
³

et al. 2015
Phys. Rev. B
19
1
20
0
View full text Add to dashboard Cite