Spin textures of topological surface states at side surfaces ofBi2Se3from first principles

John W. Villanova, Kyungwha Park
2016 Physical review B  
We investigate the spin and spin-orbital textures and electronic structures of topologically protected surface states at side surfaces of Bi 2 Se 3 by using slab models within density-functional theory (DFT). This is motivated by recent experiments on nanowires, nanoribbons, and nanoplates of Bi 2 Se 3 with side surfaces. In particular, two representative surfaces normal to the (111) surface, such as (110) and (112) surfaces, are examined, in the presence of time-reversal symmetry and inversion
more » ... symmetry. The (110) surface lying in the mirror plane has twofold (C 2 ) rotational symmetry, whereas the (112) surface has only mirror symmetry. For the (110) surface, we find that a Dirac cone with strongly anisotropic Fermi velocity is formed at Γ with the Dirac point at the Fermi level, and that the spin texture reveals features of Rashba-type combined with Dresselhaus-type spin-orbit coupling. For the (112) surface, a Dirac cone is found at either Γ or the Y point (along the mirror symmetry axis) below the Fermi level. In this case, the spin texture of the surface states strikingly differs from that of the (111) and (110) surfaces: (i) the in-plane spin polarization dominantly aligned perpendicular to the [111] direction or the mirror symmetry axis, (ii) the Dresselhaus-like spin texture, and (iii) significant out-of-plane spin polarization away from the mirror symmetry axis. Our findings distinctively differ from the previous works based on the effective bulk model Hamiltonian. Our calculated spin and spin-orbital textures and band structures can be observed by spin-resolved angle-resolved photoemission spectroscopy.
doi:10.1103/physrevb.93.085122 fatcat:d4d65olmpfe7fmepy7qsykmiqe