Untitled

Shelimova, L. E.; Karpinskii, O. G.; Константинов, П. П.; Kretova, M. A.; Avilov, E. S.; Zemskov, V. S.

doi:10.1023/a:1017519625907

Cited by 135 publications

(145 citation statements)

References 13 publications

Supporting

Mentioning

132

Contrasting

Order By: Relevance

“…The downstep is marked as region-I in the figure. The total measured thickness of the step between regions I and III is ∼30.5Å, in excellent agreement with the thickness of one unit cell [11] (i.e. three quintuples).…”

Section: Fig 2: A)supporting

confidence: 75%

STM Imaging of Electronic Waves on the Surface ofBi2Te3: Topologically Protected Surface States and Hexagonal Warping Effects

et al. 2010

View full text Add to dashboard Cite

Scanning tunneling spectroscopy studies on high-quality Bi2Te3 crystals exhibit perfect correspondence to ARPES data, hence enabling identification of different regimes measured in the local density of states (LDOS). Oscillations of LDOS near a step are analyzed. Within the main part of the surface band oscillations are strongly damped, supporting the hypothesis of topological protection. At higher energies, as the surface band becomes concave, oscillations appear which disperse with a particular wave-vector that may result from an unconventional hexagonal warping term.PACS numbers: 71.18.+y, 71.20.Nr, A new type of three-dimensional (3D) bulk insulating materials with surface Quantum Spin Hall Effect states protected by time reversal symmetry has been recently predicted [1], and soon afterwards observed experimentally in BiSb bulk crystals [2]. Subsequently, Bi 2 Te 3 has been argued to be a similar three-dimensional topological insulator (TI), exhibiting a bulk gap and a single, non-degenerate Dirac fermion band on the surface [3]. Indeed, recent angle resolved photoemission spectroscopy (ARPES) confirmed that prediction [4]. In particular, with appropriate hole-doping, the Fermi level could be tuned to intersect only the surface states, indicating fully gapped bulk states as is expected from a three-dimensional TI. While ARPES could confirm the nature of the band, it is still a challenge to demonstrate unambiguously the topologically "protected" nature of the surface state in Bi 2 Te 3 , or any other 3D TI system.In this paper we present scanning tunneling microscopy (STM) and spectroscopy (STS) studies on high-quality doped Bi 2 Te 3 crystals. First we show that the STS spectra exhibit remarkable correspondence to ARPES data, hence enabling us to identify each region of the local density of states (LDOS) measured. Second, by analyzing the electron-waves (Friedel-oscillations) observed near cleavage steps, we show that within the main part of the surface state band oscillations are strongly damped, a hallmark of the strong supression of backscattering, hence supporting the hypothesis of a protected band. Finally, we show that in the region in which the surface band is warped, pronounced oscillations appear, with a distinct nesting wave-vector. Possible influence of the bulk conduction band on the oscillations is also proposed.For the present study we used Sn and Cd doped single crystals of Bi 2 Te 3 (see Fig. 1a for crystal structure and Fig. 1b,c for ARPES data). Nominal doping levels between 0 and 0.27% for Sn, and up to 1% for Cd were incorporated to compensate n-type doping from vacancy and anti-site defects that are common in the Bi 2 Te 3 system. Actual doping was determined separately using chemical and Hall-effect methods and were shown by ARPES [4] to be in excellent agreement with the relative position of the Dirac point with respect to the Fermi energy. For example, undoped crystals exhibit a Dirac point at ∼ −335 meV, 0.27% Sn doping yielded a Dirac point at ∼ −300 meV, while for a typical ∼ 1% Cd...

show abstract

Section: Fig 2: A)supporting

confidence: 75%

STM Imaging of Electronic Waves on the Surface ofBi2Te3: Topologically Protected Surface States and Hexagonal Warping Effects

et al. 2010

View full text Add to dashboard Cite

show abstract

“…A thorough discussion of the important features of the data that was collected from many topography and spectroscopy scans can be found in [1], here we concentrate on scans in the vicinity of a step-edge defect that was obtained in the process of cleaving the crystal. The measured thick-ness of the step is ∼30.5Å (in excellent agreement with the thickness of one unit cell [13]), and we concentrate on the region away from the step as is shown in Fig. 1.…”

supporting

confidence: 64%

STM imaging of a bound state along a step on the surface of the topological insulator Bi2Te3

et al. 2011

View full text Add to dashboard Cite

Detailed study of the LDOS associated with the surface-state-band near a step-edge of the strong topological-insulator Bi2Te3 , reveal a one-dimensional bound state that runs parallel to the stepedge and is bound to it at some characteristic distance. This bound state is clearly observed in the bulk gap region, while it becomes entangled with the oscillations of the warped surface band at high energy [1], and with the valence band states near the Dirac point. We obtain excellent fits to theoretical predictions [2] that properly incorporate the three-dimensional nature of the problem to the surface state [3]. Fitting the data at different energies, we can recalculate the LDOS originating from the Dirac band without the contribution of the bulk bands or incoherent tunneling effects. [8,9], and by scanning tunneling microscopy (STM) and spectroscopy (STS) [1,10,11] experiments confirmed that prediction. Focusing on Bi 2 Te 3 , ARPES revealed that with appropriate hole-doping, the Fermi level could be tuned to intersect only the surface states, indicating fully gapped bulk states as is expected from a three-dimensional TI [8,9]. Complementing ARPES, STM and STS studies emphasizing quasi particle scattering interference from impurities and macroscopic defects, demonstrated the "protected" nature of the surface band [1,10,11].While protection of the surface state is guaranteed within a simple Dirac band, warping effects can produce special nesting wavevectors that allow for electronicwaves within the surface state band (SSB) [12]. These effects have been observed experimentally in the upper part of the SSB by Alpichshev et al. [1]. In that paper we reported STS studies on high-quality Bi 2 Te 3 crystals which exhibit oscillations of LDOS near a step-edge. While within the main part of the SSB oscillations were shown to be strongly damped, supporting the hypothesis of topological protection, at higher energies, as the SSB becomes concave (as is observed by complementary ARPES data), oscillations appear which disperse with a particular wave-vector corresponding to the allowed spin states of the warped constant-energy contour [5] .In this paper we present a more detailed study of the LDOS associated with the SSB near a step-edge, and report on the observation of what is most probably a one-dimensional (1D) state bound onto it. This bound state is clearly observed in the bulk gap region, while it becomes entangled with the oscillations of the warped SSB at high energy and with the valence band states near near the Dirac point. We successfully fit the data to theoretical predictions [2] that properly incorporate the three-dimensional nature of the problem (outlined in [3]) to the surface state . Fitting the data at different energies, we can recalculate the LDOS originating from the Dirac band without the contribution of the bulk bands or incoherent tunneling effects. The excellent agreement between the experimental data and simple theory is another testimony to the simple, yet robust nature of the surface state in this m...

show abstract

“…A large number of new materials with promising thermoelectric properties have been investigated. These include, for example, filled skutterudites, 1,2 clathrates, 3 pentatellurides, 4 half-Heusler-alloys, [5][6][7] ternary and quaternary heavy metal chalcogenides, [8][9][10][11] and layered cobalt oxides. [12][13][14] In addition, the efficiency of well-known thermoelectric materials such as Bi 2 Te 3 and PbTe has been improved dramatically by incorporation into nanostructured devices.…”

Section: Introductionmentioning

confidence: 99%

Structures and thermoelectric properties of the infinitely adaptive series(Bi2)m(Bi2Te3
Bos
¹
,
Zandbergen
²
,
Lee
³

et al. 2007
Phys. Rev. B
194
14
129
1
View full text Add to dashboard Cite

Untitled

Cited by 135 publications

References 13 publications

STM Imaging of Electronic Waves on the Surface ofBi2Te3: Topologically Protected Surface States and Hexagonal Warping Effects

STM Imaging of Electronic Waves on the Surface ofBi2Te3: Topologically Protected Surface States and Hexagonal Warping Effects

STM imaging of a bound state along a step on the surface of the topological insulator Bi2Te3

Structures and thermoelectric properties of the infinitely adaptive series(Bi2)m(Bi2Te3
Bos
¹
,
Zandbergen
²
,
Lee
³

et al. 2007
Phys. Rev. B
194
14
129
1
View full text Add to dashboard Cite

Contact Info

Product

Resources

About

Untitled

Cited by 135 publications

References 13 publications

STM Imaging of Electronic Waves on the Surface ofBi2Te3: Topologically Protected Surface States and Hexagonal Warping Effects

STM Imaging of Electronic Waves on the Surface ofBi2Te3: Topologically Protected Surface States and Hexagonal Warping Effects

STM imaging of a bound state along a step on the surface of the topological insulator Bi2Te3

Structures and thermoelectric properties of the infinitely adaptive series(Bi2)m(Bi2Te3Bos1, Zandbergen2, Lee3 et al. 2007Phys. Rev. B194141291View full textAdd to dashboardCite

Contact Info

Product

Resources

About

Structures and thermoelectric properties of the infinitely adaptive series(Bi2)m(Bi2Te3
Bos
¹
,
Zandbergen
²
,
Lee
³

et al. 2007
Phys. Rev. B
194
14
129
1
View full text Add to dashboard Cite