Topological surface states of Bi-doped PbSb2Te4 [Pb(Bi0.20Sb0.80)2Te4] are
investigated through analyses of quasiparticle interference (QPI) patterns
observed by scanning tunneling microscopy. Interpretation of the experimental
QPI patterns in the reciprocal space is achieved by numerical QPI simulations
using two types of surface density of states produced by density functional
theory calculations or a kp surface state model. We found that the Dirac point
(DP) of the surface state appears in the bulk band gap of this material and,
with the energy being away from the DP, the isoenergy contour of the surface
state is substantially deformed or separated into segments due to hybridization
with bulk electronic states. These findings provide a more accurate picture of
topological surface states, especially at energies away from the DP, providing
valuable insight into the electronic properties of topological insulators.Comment: 7+8 pages, 4+5 figure