Probing the wavefunction of the surface states in Bi_{2}Se_{3} topological insulator: a realistic tightbinding approach
Abstract
We present results of a microscopic tightbinding modeling of Bi_{2}Se_{3} threedimensional topological insulator using a sp ^{3} SlaterKoster Hamiltonian, with parameters calculated from density functional theory. Based on the calculated atomic and orbitalprojections of the wavefunctions associated with valence and conductionband states at the center of the Brillouin zone, we propose a realspace description of band inversion for both bulk and a slab of finite thickness. A systematic analysis of the key features of the surface states, in particular the spatial distribution and the spincharacter of the surface states wavefunction, is carried out for slabs of different thickness, ranging from one to tens of quintuple layers. We obtain an estimate of the slab thickness at which the energy gap induced by interaction between the top and bottom surface states becomes negligible, based on the present available numerical precision. We anticipate that this finding will be relevant for all microscopic calculations addressing the effect of external perturbations on the surface states near the Dirac point. The modifications in the helical spintexture of the Diraccone surface states, in the form of inplane and outofplane spin projections, are calculated as a function of the slab thickness. These calculations are important for the interpretation of ongoing experiments, which probe the spinpolarization of the surface states in topological insulator thin films.
 Publication:

New Journal of Physics
 Pub Date:
 June 2014
 DOI:
 10.1088/13672630/16/6/063022
 arXiv:
 arXiv:1311.0691
 Bibcode:
 2014NJPh...16f3022P
 Keywords:

 Condensed Matter  Mesoscale and Nanoscale Physics
 EPrint:
 11 pages, 11 figures