scholarly journals Band structure of a HgTe-based three-dimensional topological insulator

2020 ◽  
Vol 102 (11) ◽  
Author(s):  
J. Gospodarič ◽  
V. Dziom ◽  
A. Shuvaev ◽  
A. A. Dobretsova ◽  
N. N. Mikhailov ◽  
...  
Keyword(s):  
Band Structure ◽  
Topological Insulator ◽  
Three Dimensional

scholarly journals Possible Three-Dimensional Topological Insulator in Pyrochlore Oxides

Symmetry ◽  
2020 ◽  
Vol 12 (7) ◽  
pp. 1076
Author(s):  
Izumi Hase ◽  
Takashi Yanagisawa
Keyword(s):  
Band Structure ◽  
Topological Insulator ◽  
Nearest Neighbor ◽  
Tight Binding ◽  
Three Dimensional ◽  
Tight Binding Model ◽  
Coupling Constant ◽  
Binding Model ◽  
Effective Spin ◽  
Pyrochlore Oxides

A Kene–Mele-type nearest-neighbor tight-binding model on a pyrochlore lattice is known to be a topological insulator in some parameter region. It is an important task to realize a topological insulator in a real compound, especially in an oxide that is stable in air. In this paper we systematically performed band structure calculations for six pyrochlore oxides A2B2O7 (A = Sn, Pb, Tl; B = Nb, Ta), which are properly described by this model, and found that heavily hole-doped Sn2Nb2O7 is a good candidate. Surprisingly, an effective spin–orbit coupling constant λ changes its sign depending on the composition of the material. Furthermore, we calculated the band structure of three virtual pyrochlore oxides, namely In2Nb2O7, In2Ta2O7 and Sn2Zr2O7. We found that Sn2Zr2O7 has a band gap at the k = 0 (Γ) point, similar to Sn2Nb2O7, though the band structure of Sn2Zr2O7 itself differs from the ideal nearest-neighbor tight-binding model. We propose that the co-doped system (In,Sn)2(Nb,Zr)2O7 may become a candidate of the three-dimensional strong topological insulator.

EXCITON INSULATOR STATES IN MATERIALS WITH ‘MEXICAN HAT’ BAND STRUCTURE DISPERSION AND IN GRAPHENE

2015 ◽  
Vol 11 (1) ◽  
pp. 2927-2949
Author(s):  
Lyubov E. Lokot
Keyword(s):  
Band Structure ◽  
Three Dimensional ◽  
Dimensional Sphere ◽  
Electron Hole ◽  
Dinger Equation ◽  
Fermi Sphere ◽  
Zinc Blende ◽  
Bulk Gan ◽  
Structure Dispersion ◽  
Excitonic States

In the paper a theoretical study the both the quantized energies of excitonic states and their wave functions in grapheneand in materials with "Mexican hat" band structure dispersion as well as in zinc-blende GaN is presented. An integral twodimensionalSchrödinger equation of the electron-hole pairing for a particles with electron-hole symmetry of reflection isexactly solved. The solutions of Schrödinger equation in momentum space in studied materials by projection the twodimensionalspace of momentum on the three-dimensional sphere are found exactly. We analytically solve an integral twodimensionalSchrödinger equation of the electron-hole pairing for particles with electron-hole symmetry of reflection. Instudied materials the electron-hole pairing leads to the exciton insulator states. Quantized spectral series and lightabsorption rates of the excitonic states which distribute in valence cone are found exactly. If the electron and hole areseparated, their energy is higher than if they are paired. The particle-hole symmetry of Dirac equation of layered materialsallows perfect pairing between electron Fermi sphere and hole Fermi sphere in the valence cone and conduction cone andhence driving the Cooper instability. The solutions of Coulomb problem of electron-hole pair does not depend from a widthof band gap of graphene. It means the absolute compliance with the cyclic geometry of diagrams at justification of theequation of motion for a microscopic dipole of graphene where >1 s r . The absorption spectrums for the zinc-blendeGaN/(Al,Ga)N quantum well as well as for the zinc-blende bulk GaN are presented. Comparison with availableexperimental data shows good agreement.

scholarly journals Erratum: Magnetotransport signatures of three-dimensional topological insulator nanostructures [Phys. Rev. B 97 , 245429 (2018)]

2021 ◽  
Vol 103 (7) ◽  
Author(s):  
Kristof Moors ◽  
Peter Schüffelgen ◽  
Daniel Rosenbach ◽  
Tobias Schmitt ◽  
Thomas Schäpers ◽  
...  
Keyword(s):  
Topological Insulator ◽  
Three Dimensional
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