Quantum spin Hall insulator with a large bandgap, Dirac fermions, and bilayer graphene analog

Криштопенко, С. С.; Теппе, Ф.

doi:10.1126/sciadv.aap7529

Cited by 41 publications

(45 citation statements)

References 42 publications

(80 reference statements)

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“…Experimental relevance and summary.-Now we briefly discuss the experimental relevance for our proposal. QSHIs with large inverted gaps [44][45][46][47][48][49][50][51][52][53][54][55][71][72][73] in proximity to cuprate or iron-based superconductors [38][39][40][57][58][59][60][61] could provide promising platforms to detect our predictions. For concreteness, we take the inverted InAs/GaSb bilayer and WTe 2 monolayer to estimate µ c x(y) .…”

Section: Arxiv:190509308v1 [Cond-matsupr-con] 22 May 2019mentioning

confidence: 99%

“…This condition indeed corresponds to the QSHI phase with a large inverted gap or equivalently an indirect bulk gap. It is likely realized in the inverted InAs/GaSb bilayer [71][72][73], WTe 2 monolayer [44][45][46][47][48], functionalized MXene [49,50], Bismuthene on SiC [51,52], PbS monolayer [53][54][55], etc. To test the analytical results, we discretize the model (1), put it on a lattice, choose a proper set of parameters (satisfying inequality (8)) and calculate the energy spectrum in a ribbon geometry.…”

Section: Arxiv:190509308v1 [Cond-matsupr-con] 22 May 2019mentioning

confidence: 99%

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Detection of second-order topological superconductors by Josephson junctions

Zhang

Trauzettel

2020

Phys. Rev. Research

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We study Josephson junctions based on a second-order topological superconductor (SOTS) which is realized in a quantum spin Hall insulator with a large inverted gap in proximity to an unconventional superconductor. We find that tuning the chemical potential in the superconductor strongly modifies the pairing gap of the helical edge states and leads to topological phase transitions. As a result, the supercurrent in the junction is controllable and a 0-π transition is realized by tuning the chemical potentials in the superconducting leads. These striking features are stable in junctions with different sizes, doping in the normal region, and in the presence of disorder. We propose them as novel experimental signatures of SOTSs. Moreover, the 0-π transition can serve as a fully electric way to create or annihilate Majorana bound states in the junction without magnetic manipulation.Introduction.-The second-order topological superconductor (SOTS) is a novel topological phase of matter and features Majorana zero-dimensional (0D) corner or 1D hinge states which are two dimensions lower than the gapped bulk [1-12] and may provide stable qubits for topological quantum computation [13][14][15][16][17][18][19][20][21]. Recently, the SOTS has been discovered in a variety of realistic materials and triggered tremendous interest [3][4][5][6][7][8][9][10][22][23][24][25][26][27]. One way to mimic SOTSs in 2D is given by quantum spin Hall insulators (QSHIs) in proximity to unconventional superconductors with d x 2 −y 2 -wave or s ± -wave pairing order [3][4][5]. The proximity effect of unconventional superconductivity in 2D systems has also been intensively explored in theory [28][29][30][31][32][33][34][35][36][37] and experiment [38][39][40][41][42][43]. To date, however, the only way proposed to detect 2D SOTSs is a tunneling experiment without a concrete calculation of the observable signature. An alternative or complementary approach to probe SOTSs and manipulate the Majorana corner modes is thus desirable. In QSHIs, a finite doping is usually inevitable, and the chemical potential can be far away from the Dirac points. Therefore, it is interesting and relevant to explore the influence of the chemical potential in SOTSs.

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Section: Arxiv:190509308v1 [Cond-matsupr-con] 22 May 2019mentioning

confidence: 99%

Section: Arxiv:190509308v1 [Cond-matsupr-con] 22 May 2019mentioning

confidence: 99%

Detection of second-order topological superconductors by Josephson junctions

Zhang

Trauzettel

2020

Phys. Rev. Research

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“…The light-hole contribution is only relevant for wave vectors away from the Γ-point and/or energies well below the hybridization region. This means that in order to correctly describe the low-energy spectrum of such SQW there is no need to include the light-hole band although the need to include one extra electron band [7].…”

Section: Massless Dirac Fermionsmentioning

confidence: 99%

“…Furthermore, electrical control of the topological phase transition is possible [37,38,39] and has been reported for InAs/GaSb AQWs [6,40,41,42,43]. Although very recently Krishtopenko and Teppe [7] proposed that threelayer InAs/GaSb quantum well (QWs) hosts topological phase transition, their focus was on the strain engineering of the band gap of the InAs/GaInSb QWs which they claim is of the order of 60 meV. Instead, we focus on the electrical control, of the phase transition and the behavior of the helical edge states in such three-layer QWs, using an applied electric field but neglecting e-e interaction and disorder effects.…”

Section: Introductionmentioning

confidence: 99%

Electrical tuning of helical edge states in topological multilayers

Campos¹,

Sandoval²,

Diago‐Cisneros³

et al. 2019

J. Phys.: Condens. Matter

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Mainstream among topological insulators, GaSb/InAs quantum wells present a broken gap alignment for the energy bands which supports the quantum spin Hall insulator phase and forms an important building block in the search of exotic states of matter. Such structures allow the band-gap inversion with electrons and holes confined in adjacent layers, providing a fertile ground to tune the corresponding topological properties. Using a full 3D 8-band k · p method we investigate the inverted band structure of GaSb/InAs/GaSb and InAs/GaSb/InAs multilayers and the behavior of the helical edge states, under the influence of an electric field applied along the growth direction. By tuning the electric field modulus, we induce the change of the energy levels of both conduction and valence bands, resulting in a quantum spin Hall insulator phase where the helical edge states are predominantly confined in the GaSb layer. In particular, we found that InAs/GaSb/InAs has a large hybridization gap of about 12 meV and, therefore, are promising to observe massless Dirac fermions with a large Fermi velocity. Our comprehensive characterization of GaSb/InAs multilayers creates a basis platform upon which further optimization of III-V heterostructures can be contrasted. arXiv:1903.02687v3 [cond-mat.mes-hall]

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“…[2][3][4][5] A fundamentally important perspective of application for these materials is their use as quantum spin Hall insulator (QSHI) and three-dimensional (3D) topological insulators, opening possibilities for low-power nanoscale electronic and spintronic applications. [6,7] In this sense, graphene alone is deficient, because its low spin-orbit coupling (SOC) gives origin to a small bulk band gap of the order of 10 −3 meV. [8,9] In the group of materials that can be exfoliated into monolayers and that have been predicted to be QSHI are the 1T ′ polytypes of some transition metal dichalcogenides, [10] with scanning tunneling microscopy work detecting edge states for WTe 2 , [11,12] MoS 2 , [13] and WSe 2 .…”

Section: Introductionmentioning

confidence: 99%

Raman spectrum of layered jacutingaite (Pt₂HgSe₃) crystals—Experimental and theoretical study

Longuinhos

Vymazalová

Cabral

et al. 2019

J Raman Spectroscopy

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Jacutingaite (Pt2HgSe3) is a recently discovered layered platinum‐group mineral. Recent experimental studies have shown that it displays the properties of a quantum spin Hall insulator (QSHI), and theoretical studies indicate that its two‐dimensional monolayer is a QSHI with a robust topological gap of ∼0.5 eV. Jacutingaite is thus promising for potential applications to nanoelectronics and spintronics. The Raman spectrum of three‐dimensional bulk jacutingaite and the symmetries of its vibrational modes, fundamental for understanding structural modifications of this material, are still unexplored. Here, we address the zone‐center Raman optical phonons of bulk jacutingaite by experiments, symmetry, and first‐principles calculations. The improved synthesis used here provided crystals of higher purity and of micrometer size, allowing the study of single crystals. Polarized Raman spectroscopy was used to assign the symmetries of nine out of the 11 Raman‐active modes expected by group theory and their respective selection rules. The calculated wavenumbers of the Raman‐active modes, in addition to their atomic displacements, are in very good agreement with experiments. In addition, we discuss the use of different exchange correlation functionals within density functional theory, as local functionals and nonlocal functionals that best describe van der Waals interactions. The influence of the inclusion of spin–orbit coupling on calculated vibrational phonon wavenumbers and lattice parameters is commented, and it was found that the local density approximation provides a good description. Our results are of paramount importance to further exploitation of the effects of jacutingaite's structural modifications to tune its properties, as well as for its structural, optical, electronic, mechanical, and thermal applications.

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Quantum spin Hall insulator with a large bandgap, Dirac fermions, and bilayer graphene analog

Abstract: We propose a new III–V semiconductor system hosting a large-gap quantum spin Hall insulator and unconventional metal states.

Cited by 41 publications

References 42 publications

Detection of second-order topological superconductors by Josephson junctions

Detection of second-order topological superconductors by Josephson junctions

Electrical tuning of helical edge states in topological multilayers

Raman spectrum of layered jacutingaite (Pt₂HgSe₃) crystals—Experimental and theoretical study

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Quantum spin Hall insulator with a large bandgap, Dirac fermions, and bilayer graphene analog

Abstract: We propose a new III–V semiconductor system hosting a large-gap quantum spin Hall insulator and unconventional metal states.

Cited by 41 publications

References 42 publications

Detection of second-order topological superconductors by Josephson junctions

Detection of second-order topological superconductors by Josephson junctions

Electrical tuning of helical edge states in topological multilayers

Raman spectrum of layered jacutingaite (Pt2HgSe3) crystals—Experimental and theoretical study

Contact Info

Product

Resources

About

Raman spectrum of layered jacutingaite (Pt₂HgSe₃) crystals—Experimental and theoretical study