Anomalous galvanomagnetism, cyclotron resonance, and microwave spectroscopy of topological insulators

Tkachov, G.; Hankiewicz, Ewelina M.

doi:10.1103/physrevb.84.035405

Cited by 62 publications

(148 citation statements)

References 29 publications

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“…Recently the quantum diffusion transport was also theoretically studied for the HgTe quantum well, 19 where the suppression of weak antilocalization (corresponding to the unitary behavior in this work) was also found for the BHZ model. Beyond the suppression of the weak antilocalization, we also expect the weak localization in the HgTe quantum well because the BHZ model can also be classified as the modified Dirac model.…”

Section: Magnetoconductivity For 2d Modified Dirac Modelmentioning

confidence: 99%

“…Different from the Berry phase in absence of Bk 2 σ z term, 57 one may also have the π Berry phase as well as the weak antilocalization at 2πρ = k 2 F = M/2B, where ρ is the sheet carrier density of investigated band. 19 Moreover, Dk 2 F may effectively reduce E F to E F − Dk 2 F , reminding that the effective model for the gapless surface states also contains the Dk 2 term, 41,58 this may explain the earlier crossover to weak localization at relatively large E F . 13 Because the Berry phase depends on cos Θ, the crossover can also be understood by the pseudospin orientation along z direction.…”

Section: Magnetoconductivity For 2d Modified Dirac Modelmentioning

confidence: 99%

“…4,5 One of intriguing transport features of topological insulators is the weak antilocalization (WAL), appearing as the negative magnetoconductivity with a sharp cusp in low fields. [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] WAL is intrinsic to topological insulators: (i) so far, most samples have low mobility and long coherence length, making the quantum interference an important correction to the diffusion transport; (ii) due to the spinmomentum locking resulted from strong spin-orbit coupling, the single gapless Dirac cone of the topological surface states carries a π Berry phase, 21,22 which changes the interference of time-reversed scattering loops from constructive to destructive. The destructive interference will give the conductivity an enhancement, which can be destroyed by applying a magnetic field that breaks the π Berry phase, leading to the negative magnetoconductivity with the cusp.…”

Section: Introductionmentioning

confidence: 99%

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Weak localization of bulk channels in topological insulator thin films

2011

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Weak antilocalization (WAL) is expected whenever strong spin-orbit coupling or scattering comes into play. Spin-orbit coupling in the bulk states of a topological insulator is very strong, enough to result in the topological phase transition. However, the recently observed WAL in topological insulators seems to have an ambiguous origin from the bulk states. Starting from the effective model for three-dimensional topological insulators, we find that the lowest two-dimensional (2D) bulk subbands of a topological insulator thin film can be described by the modified massive Dirac model. We derive the magnetoconductivity formula for both the 2D bulk subbands and surface bands. Because with relatively large gap, the 2D bulk subbands may lie in the regimes where the unitary behavior or even weak localization (WL) is also expected, instead of always WAL. As a result, the bulk states may contribute small magnetoconductivity or even compensate the WAL from the surface states. Inflection in magnetoconductivity curves may appear when the bulk WL channels outnumber the surface WAL channels, providing a signature of the weak localization from the bulk states.

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Section: Magnetoconductivity For 2d Modified Dirac Modelmentioning

confidence: 99%

Section: Magnetoconductivity For 2d Modified Dirac Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Weak localization of bulk channels in topological insulator thin films

2011

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“…3(b) (for clarity, only four representative curves are plotted). The 2D WAL MR in perpendicular B fields and in the limit of strong spin-orbit scattering (which is pertinent to TIs) can be written as [5][6][7]38 …”

Section: B Weak-antilocalization Magnetoresistancementioning

confidence: 99%

“…In the absence of any magnetic scattering, the time-reversal coherent backscattering would thus be suppressed, leading to the well-known weak antilocalization (WAL) effect which manifests positive magnetoresistances (MRs) in low perpendicular magnetic fields. [4][5][6][7] Although an observation of the two-dimensional (2D) WAL effect can be a signature of the existence of TI surface states, the strong spin-orbit coupling in the bulk conduction channel can also contribute to a WAL effect. This situation often happens in the three-dimensional (3D) TIs, such as the p-type Bi 2 Te 3 and the n-type Bi 2 Se 3 , owing to the high levels of unintentional doping which readily occurs during the sample growth as well as the device fabrication processes.…”

Section: Introductionmentioning

confidence: 99%

Weak antilocalization in topological insulator Bi2Te3microflakes

2013

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We have studied the carrier transport in two topological insulator (TI) Bi2Te3 microflakes between 0.3 and 10 K and under applied backgate voltages (VBG). Logarithmic temperature dependent resistance corrections due to the two-dimensional electron-electron interaction effect in the presence of weak disorder were observed. The extracted Coulomb screening parameter is negative, which is in accord with the situation of strong spin-orbit scattering as is inherited in the TI materials. In particular, positive magnetoresistances (MRs) in the two-dimensional weak-antilocalization (WAL) effect were measured in low magnetic fields, which can be satisfactorily described by a multichannelconduction model. Both at low temperatures of T < 1 K and under high positive VBG, signatures of the presence of two coherent conduction channels were observed, as indicated by an increase by a factor of ≈ 2 in the prefactor which characterizes the WAL MR magnitude. Our results are discussed in terms of the (likely) existence of the Dirac fermion surface states, in addition to the bulk states, in the three-dimensional TI Bi2Te3 material.

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Spin‐helical transport in normal and superconducting topological insulators

Tkachov

Hankiewicz

2013

Physica Status Solidi (b)

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31 85141In a topological insulator (TI) the character of electron transport varies from insulating in the interior of the material to metallic near its surface. Unlike, however, ordinary metals, conducting surface states in TIs are topologically protected and characterized by spin helicity whereby the direction of the electron spin is locked to the momentum direction. In this paper we review selected topics regarding recent theoretical and experimental work on electron transport and related phenomena in two-dimensional (2D) and three-dimensional (3D) TIs.The review provides a focused introductory discussion of the quantum spin Hall effect in HgTe quantum wells as well as transport properties of 3DTIs such as surface weak antilocalization, the half-integer quantum Hall effect, s þ p-wave induced superconductivity, superconducting Klein tunneling, topological Andreev bound states and related Majorana midgap states. These properties of TIs are of practical interest, guiding the search for the routes towards topological spin electronics. 1 Introduction The situation when a material behaves as a metal in terms of its electric conductivity and, at the same time, as an insulator in terms of its band structure is extremely unconventional from the viewpoint of the standard classification of solids. That is why the recent discovery of a class of such materials -topological insulators (TIs) -has generated much interest (see e.g., reviews [1,2]). The dual properties of the TIs are especially well pronounced in two-dimensional (2D) systems which are also known as quantum spin-Hall insulators (QSHIs) [3][4][5][6][7]. In QSHIs, the metallic electric conduction is associated with propagating states that occur only near the sample edges, while the conduction in the interior is suppressed by a band gap like in ordinary band insulators. These edge states originate from intrinsic spin-orbit (SO) coupling and are profoundly different from those appearing in quantum Hall systems in a strong perpendicular magnetic field [8,9]. The key distinction lies in the role of the time reversal symmetry. In the QSHIs the SO coupling preserves the time-reversal symmetry, resulting in a pair of counter-propagating channels on the same edge as opposed to one-way directed (chiral) edge states in quantum Hall systems. Remarkably, the spin and momentum directions of the two QSHI edge channels are locked in the opposite ways so that these states are characterized by opposite spin helicities and orthogonal

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Anomalous galvanomagnetism, cyclotron resonance, and microwave spectroscopy of topological insulators

Cited by 62 publications

References 29 publications

Weak localization of bulk channels in topological insulator thin films

Weak localization of bulk channels in topological insulator thin films

Weak antilocalization in topological insulator Bi2Te3microflakes

Spin‐helical transport in normal and superconducting topological insulators

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