Chemical modification of Sb thin film

Antimony films is known to exhibit topological surface states depending on the thickness of the film. The surface states near Γ point own the linear crossing dispersion and possess time-reversal symmetry. The chemical adsorption on the one-side pristine surface could induce the large asymmetry in this film and suppress quantum tunneling. In this chapter, we use density functional calculation to investigate the electronic structure of the four-bilayer Sb film and find that adsorptions of impurity atoms on the film. The binding energies of the impurity atoms on the Sb film are also calculated and they are generally associated with charge transfer between the transition metals and Sb film. Our calculations have shown that adsorptions of non-magnetic impurity atoms of hydrogen, copper, or zinc on a four-bilayer Sb thin film actually facilitate the formation of Dirac cones that preserve time-reversal symmetry. But magnetic atoms such as iron and manganese do just the opposite. The results suggest the counterintuitive concept of achieving topological conduction by doping nonmagnetic foreign atoms on thin films of topological insulators.