Hybridization of topological surface states with a flat band

Sergey S. Krishtopenko, Mauro Antezza, Frédéric Teppe

Published 2018-12-06Version 1

We address the problem of hybridization between topological surface states and non-topological flat bulk band within an analytical Hamiltonian linear in quasimomentum. Our model is based on a mixture of the three-dimensional Bernevig-Hughes-Zhang and the two-dimensional pseudospin-1 Dirac-Weyl Hamiltonian, hence it also includes the case of HgTe-class and Cd$_3$As$_2$ crystals at given hybridization strength. We show that hybridization with a bulk band in HgTe transforms initial Dirac-like surface states into two branches below the flat band and above the edge of conduction band. Dispersion of the lower branch depends on hybridization strength, while the upper branch always remains "massive" for any hybridization strength. By varying the position of the bulk flat band, we obtain a picture of the surface states for topological insulators and the appearance of the Fermi arcs for Dirac semimetals based on HgTe and Cd$_3$As$_2$ crystals at different strength of hybridization.