Electronic structures and surface states of the topological insulator Bi1-xSbx

We investigate the electronic structures of the alloyed Bi1-xSbx compounds based on first-principles calculations including spin-orbit coupling (SOC), and calculate the surface states of semi-infinite systems using maximally localized Wannier function. From the calculated results, we analyze the topological nature of Bi1-xSbx, and found the followings: (1) pure Bi crystal is topologically trivial. (2) Topologically nontrivial phase can be realized by reducing the strength of SOC via Sb doping. (3) The indirect bulk band gap, which is crucial to realize the true bulk insulating phase, can be enhanced by uniaxial pressure along c axis. (4) The calculated surface states can be compared with experimental results, which confirms the topological nature. (5) We predict the spin-resolved Fermi surfaces and showed the vortex structures, which should be examined by future experiments.