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arXiv · 0910.2822

Electronic structure near an impurity and terrace on the surface of a 3-dimensional topological insulator

Qiang-Hua Wang·Da Wang·Fu-Chun Zhang
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Abstract

Motivated by recent scanning tunneling microscopy experiments on surfaces of Bi$_{1-x}$Sb$_{x'}$\cite{yazdanistm,gomesstm} and Bi$_2$Te$_3$,\cite{kaptunikstm,xuestm} we theoretically study the electronic structure of a 3-dimensional (3D) topological insulator in the presence of a local impurity or a domain wall on its surface using a 3D lattice model. While the local density of states (LDOS) oscillates significantly in space at energies above the bulk gap, the oscillation due to the in-gap surface Dirac fermions are very weak. The extracted modulation wave number as a function of energy satisfies the Dirac dispersion for in-gap energies and follows the border of the bulk continuum above the bulk gap. We have also examined analytically the effects of the defects by using a pure Dirac fermion model for the surface states and found that the LDOS decays asymptotically faster at least by a factor of 1/r than that in normal metals, consistent with the results obtained from our lattice model.

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Qiang-Hua Wang, Da Wang, Fu-Chun Zhang. 2009-10-15. Electronic structure near an impurity and terrace on the surface of a 3-dimensional topological insulator. https://doi.org/10.1103/physrevb.81.035104

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