Edge absorption and pure spin current in a 2D topological insulator in the Volkov–Pankratov model

Mahmoodian, M. M.; Magarill, L. I.; Entin, M V

doi:10.1088/1361-648x/aa8849

Cited by 10 publications

(12 citation statements)

References 43 publications

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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%

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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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Section: Random Volkov-pankratov Modelmentioning

confidence: 99%

“…The edge states on the curved edges were studied also 22 . It was found that the microwave absorption in the insulating phase is a result of the transitions from the edge-state to 2D states or between the edge states with the opposite direction of motion with 2D states virtual participation 23 .…”

Section: Introductionmentioning

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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“…However, for straight edges, the transitions within the edge states are forbidden, unless the unusual processes including virtual transitions with the participation of 2D states are taken into account. At the same time, the transitions between the edge states and the 2D states have their low‐frequency threshold . Hence, Equation is valid until the frequency is low enough, but not too low due to the necessity for including the quantization of an electron motion along the edge.…”

Section: Light Absorption Due To Intra‐edge‐state Transitionsmentioning

confidence: 99%

“…Important, is that the topologically protected VP edge states appear near the lines where the gap changes its sign. The width fluctuations lead to multiple internal edges in a sample [12][13][14], while the external border of TI in these systems plays a less essential role.…”

Section: Introductionmentioning

confidence: 99%

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

Mahmoodian

Éntin

2019

Physica Status Solidi (b)

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A 2D HgTe quantum well is analyzed based on the assumption that the width fluctuations convert the system to a random mixture of domains with positive and negative energy gaps. The borders between ordinary and topological insulator phases form a network of the edge states covering the entire sample. The optical transitions within the edge states yield a 2D absorption. The qualitative consideration is based on the model of optical intraedge transitions in curved edge states together with percolation arguments.

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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%

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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Edge absorption and pure spin current in a 2D topological insulator in the Volkov–Pankratov model

Cited by 10 publications

References 43 publications

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

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

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

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

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