STM imaging of a bound state along a step on the surface of the topological insulator Bi2Te3

We present a detailed study of the local density of states (LDOS) associated with the surface-state band near a step edge of the strong topological insulator Bi2Te3 and reveal a one-dimensional bound state that runs parallel to the step edge and is bound to it at some characteristic distance. This bound state is clearly observed in the bulk gap region, while it becomes entangled with the oscillations of the warped surface band at high energy [Alpichshev et al., Phys. Rev. Lett. 104, 016401 (2010)], and with the valence-band states near the Dirac point. We obtain excellent fits to theoretical predictions [Alpichshev et al., 2011] that properly incorporate the three-dimensional nature of the problem to the surface state [Zhang et al., Nat. Phys. 5, 438 (2009)]. Fitting the data at different energies, we can recalculate the LDOS originating from the Dirac band without the contribution of the bulk bands or incoherent tunneling effects.