APS March Meeting 2011
Volume 56, Number 1
Monday–Friday, March 21–25, 2011;
Dallas, Texas
Abstract: D2.00002 : STM and STS studies of electronic states near macroscopic defects in topological insulators
3:06 PM–3:42 PM
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Author:
Bi$_{2}$Te$_{3~}$and Bi$_{2}$Se$_{3~}$have been argued recently
to be
three-dimensional (3D) topological insulators (TI), exhibiting a
bulk gap
and a single, non-degenerate Dirac fermion surface band
topologically
protected by time-reversal symmetry. In this talk we will discuss
the
physics of topological insulators. We will show that Scanning
tunneling
spectroscopy (STS) studies on high-quality Bi$_{2}$Te$_{3}$~and
Bi$_{2}$Se$_{3}$~crystals exhibit perfect correspondence to ARPES
data,
hence enabling identification of different regimes measured in
the local
density of states (LDOS). Unique to Bi$_{2}$Te$_{3}$, we will
discuss
observations of oscillations of LDOS near a step. Within the
main part of
the surface band we found that the oscillations are strongly damped,
supporting the hypothesis of topological protection. At higher
energies, as
the surface band becomes concave, oscillations appear which
disperse with a
particular wave-vector that results from an unconventional
hexagonal warping
term in the surface-state-band Hamiltonian [1]. For both systems,
a bound
state was observed in the bulk gap region that runs parallel to
the edge of
the defect and is bound to it at some characteristic distance. An
expression
that fits the data, and provides further insight into the general
topological properties of the electronic structure of the surface
band near
strong structural defects, can be obtained using the full
three-dimensional
Hamiltonian of the system.
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[1] Zhanybek Alpichshev, J. G. Analytis, J.-H. Chu, I. R. Fisher,
Y. L. Chen, Z. X. Shen, A. Fang, and A. Kapitulnik \textit{Phys.
Rev. Lett.} \textbf{104} 016401 (2010)
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2011.MAR.D2.2