Robust Level Coincidences in the Subband Structure of Quasi 2D Systems
arXiv:1011.4504 · doi:10.1016/j.ssc.2012.09.002
Abstract
Recently, level crossings in the energy bands of crystals have been identified as a key signature for topological phase transitions. Using realistic models we show that the parameter space controlling the occurrence of level coincidences in energy bands has a much richer structure than anticipated previously. In particular, we identify robust level coincidences that cannot be removed by a small perturbation of the Hamiltonian compatible with the crystal symmetry. Different topological phases that are insulating in the bulk are then separated by a gapless (metallic) phase. We consider HgTe/CdTe quantum wells as a specific example.
conclusions extended
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- Cross-section geometry effects in the subband structure and spin-related properties of a HgTe/CdTe nanowire
- Splitting of Dirac cones in HgTe quantum wells: Effects of crystallographic orientation, interface-, bulk-, and structure-inversion asymmetry
- Long-range perturbation of helical edge states by nonmagnetic defects in two-dimensional topological insulators
- Effects of electron-hole asymmetry on electronic structure of helical edge states in HgTe/HgCdTe quantum wells
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