Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
1592712 | Solid State Communications | 2012 | 4 Pages |
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.
► We study energy level coincidences in HgTe/CdTe quantum wells. ► Level coincidences may occur even if not supported by symmetry. ► Robust level coincidences are not destroyed by small system changes. ► Robust level coincidences correspond to novel metallic phase.