Low-velocity anisotropic Dirac fermions on the side surface of topological insulators

                                                                                               Hyoung Joon Choi

 We report anisotropic Dirac-cone surface bands on a side-surface geometry of the topological insulator Bi₂Se₃ revealed by first-principles density-functional calculations. We find that the electron velocity in the side-surface Dirac cone is anisotropically reduced from that in the (111)-surface Dirac cone, and the velocity is not in parallel with the wave vector k except for k in high-symmetry directions. The size of the electron spin depends on the direction of k due to anisotropic variation of the noncollinearity of the electron state. Low-energy effective Hamiltonian is proposed for side-surface Dirac fermions, and its implications are presented including refractive transport phenomena occurring at the edges of tological insulators where different surfaces meet. This work was supported by NRF of Korea (Grant No. 2009-0081204 and 2011-0018306). Computational resources have been provided by KISTI Supercomputing Center (Project No. KSC-2008-S02-0004 and KSC-2011-C2-04).

Ref) C.-Y. Moon, J. Han, H. Lee, and H. J. Choi, arXiv:1101.0210 (2011).