摘要
Topological insulators have a bulk band gap like a.n ordinary insulator and conducting states on their edge or surface which are formed by spin orbit coupling and protected by time-reversal sylnmetry. W＇e report theoretical analyses of tile electronic properties of three-dimensional topological insulator Bi2Sea film on different energies. We choose five different energies （ 123, -75, 0, 180. 350 meV） around the Dirac cone （ 113 meV）. When energy is close to the Dirac cone. the properties of wave function Inatch the topological insulator＇s halhnark perfectly. When energy is far way from tile Dirac cone, the halhnark of topological insulator is broken and the helical states disappear. The electronic properties of helical states are dug out fi＇om the calculation results. The spin-inomentum locking of the helical StatES are confirmed. A 3-fold symmetry of the helical states in Brillouin zone is also revealed. The penetration depth of tile helical states is two quintuple layers which can be identified from layer projection. Tile charge contribution on each quintuple layer depends on the energy, and has completely different behavior along K and M direction in Brillouin zone. From orbital projection, we can find that the maximum charge contribution of the helical states is p： orbit and the charge contribution on py and Px orbits have 2-fold symmetry.
Topological insulators have a bulk band gap like a.n ordinary insulator and conducting states on their edge or surface which are formed by spin orbit coupling and protected by time-reversal sylnmetry. W＇e report theoretical analyses of tile electronic properties of three-dimensional topological insulator Bi2Sea film on different energies. We choose five different energies （ 123, -75, 0, 180. 350 meV） around the Dirac cone （ 113 meV）. When energy is close to the Dirac cone. the properties of wave function Inatch the topological insulator＇s halhnark perfectly. When energy is far way from tile Dirac cone, the halhnark of topological insulator is broken and the helical states disappear. The electronic properties of helical states are dug out fi＇om the calculation results. The spin-inomentum locking of the helical StatES are confirmed. A 3-fold symmetry of the helical states in Brillouin zone is also revealed. The penetration depth of tile helical states is two quintuple layers which can be identified from layer projection. Tile charge contribution on each quintuple layer depends on the energy, and has completely different behavior along K and M direction in Brillouin zone. From orbital projection, we can find that the maximum charge contribution of the helical states is p： orbit and the charge contribution on py and Px orbits have 2-fold symmetry.
