Terahertz detection of magnetic field-driven topological phase transition in HgTe-based transistors

Kadykov, A. M.; Теппе, Ф.; Consejo, C.; Viti, Leonardo; Vitiello, Miriam S.; Криштопенко, С. С.; Ruffenach, Sandra; Morozov, S. V.; Marcinkiewicz, M.; Desrat, Wilfried; Dyakonova, N.; Knap, W.; Гавриленко, В. И.; Михайлов, Н. Н.; Dvoretsky, S. A.

doi:10.1063/1.4932943

Cited by 17 publications

(11 citation statements)

References 41 publications

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“…In this work, we propose a minimal effective 2D model, which describes the side maxima in the valence subband and qualitatively reproduces the band structure calculations based on the Kane Hamiltonian, which validity is confirmed by a large variety of experiments performed by different techniques [2][3][4]6,[25][26][27][28][29][30][31][32][33] . By using the derived 2D Hamiltonian, we explore a picture of the edge states in HgTe-based QSHIs with direct and indirect band gap.…”

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confidence: 61%

Realistic picture of helical edge states in HgTe quantum wells

Криштопенко

Теппе

2018

Phys. Rev. B

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We propose a minimal effective two-dimensional Hamiltonian for HgTe/CdHgTe quantum wells (QWs) describing the side maxima of the first valence subband. By using the Hamiltonian, we explore the picture of helical edge states in tensile and compressively strained HgTe QWs. We show that both dispersion and probability density of the edge states can differ significantly from those predicted by the Bernevig-Hughes-Zhang (BHZ) model. Our results pave the way towards further theoretical investigations of HgTe-based quantum spin Hall insulators with direct and indirect band gaps beyond the BHZ model.The inverted HgTe/CdHgTe quantum well (QW) is the first two-dimensional (2D) system, in which a quantum spin Hall insulator (QSHI) state was theoretically predicted 1 and then experimentally observed 2-4 . The origin of the topologically nontrivial QSHI state is caused by inverted band structure of bulk HgTe, which leads to a peculiar confinement effect in HgTe/CdHgTe QWs. Specifically, in narrow QWs, the first electron-like subband E 1 lies above the first hole-like level H 1, and the system is characterized by normal band ordering with trivial insulator state. As the QW width d is varied (see Fig. 1a), the E 1 and H 1 subbands are crossed 5 , and the band structure mimics a linear dispersion of massless Dirac fermions 6 . When d exceeds the critical width d c , an inversion of the E 1 and H 1 levels drives the system in QSHI state with a pair of gapless helical edge states topologically protected due to time-reversal symmetry 1 .So far, theoretical description of the phase transition between trivial and QSHI states in HgTe QWs has been based on the Bernevig-Hughes-Zhang (BHZ) 2D model 1 . The latter is derived from the Kane Hamiltonian 7 , which includes Γ 6 , Γ 8 , Γ 7 bulk bands with the confinement effect. Within the representation defined by the basis states |E 1,+ , |H 1,+ , |E 1,-, |H 1,-, the effective 2D Hamiltonian has the form:

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confidence: 61%

Realistic picture of helical edge states in HgTe quantum wells

Криштопенко

Теппе

2018

Phys. Rev. B

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“…Further, we consider QWs grown on the [0lk] plane (l and k are integer numbers), which includes the most prevalent cases of (001)-2,4-6,18 and (013)-oriented 8,10,21,22 structures. We note that previously reported 6-band k·p Hamiltonian 3,23 for general (0lk) orientation considers only Γ 6 and Γ 8 bands and includes interaction with the Γ 7 band only via the second order perturbation theory.…”

Section: Theoretical Basismentioning

confidence: 99%

Pressure- and temperature-driven phase transitions in HgTe quantum wells

et al. 2016

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We present theoretical investigations of pressure and temperature driven phase transitions in HgTe quantum wells grown on CdTe buffer. Using the 8-band k·p Hamiltonian we calculate evolution of energy band structure at different quantum well width with hydrostatic pressure up to 20 kBar and temperature ranging up 300 K. In particular, we show that in addition to temperature, tuning of hydrostatic pressure allows to drive transitions between semimetal, band insulator and topological insulator phases. Our realistic band structure calculations reveal that the band inversion under hydrostatic pressure and temperature may be accompanied by non-local overlapping between conduction and valence bands. The pressure and temperature phase diagrams are presented.

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“…The THz beam was modulated by a mechanical chopper and guided to the sample by stainless steel pipes. The transistor was placed at the center of a superconducting coil and cooled to 4.2 K. Details on experiment can be found in [17]. 3 Results and discussion At low magnetic fields, we observe broad pronounced lines, as seen in Fig.…”

Section: Introductionmentioning

confidence: 88%

Observation of topological phase transition by terahertz photoconductivity in HgTe‐based transistors

Kadykov

Consejo

Marcinkiewicz

et al. 2016

Phys. Status Solidi C

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We have found the possibility to probe the magnetic field‐driven topological phase transition in HgTe‐based transistors by measuring their Terahertz photoconductivity response. At the critical magnetic field to which zero‐mode Landau levels cross, we have observed a pronounced photoconductivity peak independent on incident frequency and carrier concentration. Our results pave the way towards terahertz topological field effect transistors. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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Terahertz detection of magnetic field-driven topological phase transition in HgTe-based transistors

Cited by 17 publications

References 41 publications

Realistic picture of helical edge states in HgTe quantum wells

Realistic picture of helical edge states in HgTe quantum wells

Pressure- and temperature-driven phase transitions in HgTe quantum wells

Observation of topological phase transition by terahertz photoconductivity in HgTe‐based transistors

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