Microwave Absorption in 2D Topological Insulators with a Developed Edge States Network

Mahmoodian, M. M.; Éntin, M. V.

doi:10.1002/pssb.201800652

Cited by 13 publications

(16 citation statements)

References 16 publications

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“…In order to estimate the width of the channels we per- formed additional measurements of the Hall effect at low magnetic fields. Surprisingly, we find that the Hall effect near the percolation threshold is completely suppressed in a narrow interval of carrier densities in agreement with the percolation model [26,27].…”

Section: Introductionsupporting

confidence: 86%

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Transport through the network of topological channels in HgTe based quantum well

Gusev,

Kvon,

Kozlov

et al. 2021

Preprint

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Topological insulators represent a new quantum state of matter which is characterized by edge or surface states and an insulating band gap in the bulk. In a two dimensional (2D) system based on the HgTe quantum well (QW) of critical width random deviations of the well width from its average value result in local crossovers from zero gap 2D Dirac fermion system to either the 2D topological insulator or the ordinary insulator, forming a complicated in-plane network of helical channels along the zero-gap lines. We have studied experimentally the transport properties of the critical width HgTe quantum wells near the Dirac point, where the conductance is determined by a percolation along the zero-gap lines. The experimental results confirm the presence of percolating conducting channels of a finite width. Our work establishes the critical width HgTe QW as a promising platform for the study of the interplay between topology and localization.

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Section: Introductionsupporting

confidence: 86%

“…In addition to the gap fluctuations there will also be variations of the electrostatic potential due to random distribution of charged impurities. For the Fermi energy located near the Dirac point the system conductivity is attributed to the percolation along zero energy channels [26,27].…”

Section: Introductionmentioning

confidence: 99%

Transport through the network of topological channels in HgTe based quantum well

Gusev,

Kvon,

Kozlov

et al. 2021

Preprint

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“…Near the critical width w 0 , the inevitable fluctuation of w(r) leads to the separation of a sample to OI and TI domains. The borders between them, where the gap 2∆(r) = 0, should form the edge states [19][20][21][22][23]25 .…”

Section: Random Volkov-pankratov Modelmentioning

confidence: 99%

Conductivity of a two-dimensional HgTe layer near the critical width: The role of developed edge states network and random mixture of p - and n -domains

Mahmoodian

Éntin

2020

Phys. Rev. B

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The conductivity of 2D HgTe quantum well with a width ∼ 6.3nm, close to the transition from ordinary to topological insulating phases, is studied. The Fermi level is supposed to get to the overall energy gap. The consideration is based on the percolation theory. We have found that the width fluctuations convert the system to a random mixture of domains with positive and negative energy gaps with internal edge states formed near zero gap lines. In the case with no potential fluctuations, the conductance of a finite sample is provided by a random network of the edge states. The zero temperature conductivity of an infinite sample is determined by the free motion of electrons along the zero-gap lines and tunneling between them.The conductance of a single p-n junction, which is crossed by the edge state, is found. The result is applied to the situation when potential fluctuations transform the system to a mixture of p-and n-domains. It is stated that the tunneling across p-n junctions forbids the low-temperature conductivity of a random system, but the latter is restored due to the random edge states crossing the junctions.

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“…In particular, the non-local conductance due to topologicallyprotected linear-edge states was observed in 7,8 , and theoretically discussed by 9 and; however, the non-locality does not obligatorily manifest itself. The edge state light absorption was theoretically [10][11][12] and experimentally investigated 13 . Different theoretical approaches to this intriguing problem were developed.…”

Section: Introductionmentioning

confidence: 99%

“…In this case the additional edge states are formed 6 , 15,16 . The gap sign, which determines if the 2D layer is OI or TI, is controlled by the layer thickness 12,17 . Due to intentional or non-intentional a smooth transition between TI and OI domains are formed near formal TI boundary.…”

Section: Introductionmentioning

confidence: 99%

Electron states on the smooth edge of 2D topological insulator: elastic backscattering and light absorption

Mahmoodian¹,

Entin²

2021

Preprint

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The 2D TI edge states are considered within the Volkov-Pankratov (VP) Hamiltonian. A smooth transition between TI and OI is assumed. The edge states are formed in the total gap of homogeneous 2D material. A pair of these states are of linear dispersion, others have gapped Dirac spectra. The optical selection rules are found. The optical transitions between the neighboring edge states appear in the global 2D gap for the in-plane light electric field directed across the edge.The electrons in linear edge states have no backscattering, that is indicative of the fact of topological protection. However, when linear edge states get to the energy domain of Dirac edge states, the backscattering becomes permitted. The elastic backscattering rate is found. The Drude-like conductivity is found when the Fermi level gets into the energy domain of the coexistence of linear and Dirac edge states. The localization edge conductance of a finite sample at zero temperature is determined.

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Microwave Absorption in 2D Topological Insulators with a Developed Edge States Network

Cited by 13 publications

References 16 publications

Transport through the network of topological channels in HgTe based quantum well

Transport through the network of topological channels in HgTe based quantum well

Conductivity of a two-dimensional HgTe layer near the critical width: The role of developed edge states network and random mixture of p - and n -domains

Electron states on the smooth edge of 2D topological insulator: elastic backscattering and light absorption

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