Robust level coincidences in the subband structure of quasi-2D systems

R. Winkler*, L. Y. Wang, Y. H. Lin, Chon-Saar Chu

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

24 Scopus citations


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.

Original languageEnglish
Pages (from-to)2096-2099
Number of pages4
JournalSolid State Communications
Issue number23
StatePublished - 1 Dec 2012


  • A. Semiconductors
  • A. Topological insulators

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