Surface states scattering from a step defect in topological insulator Bi₂Te₃

We study theoretically by a quantum-mechanical approach the general scattering problem of a straight step defect on the surface of topological insulator $\mathrm{Bi}_{2}\mathrm{Te}_{3}$ with strong warping effect. At high energy where the warping effect is large, an incident electron on a step defect running along $\Gamma-\mathrm{M}$ direction may exhibit perfect transmission whereas on a defect running along $\Gamma-\mathrm{K}$ direction has a finite probability to be reflected and may even exhibit resonant total reflection. Transmission properties in the latter case are also very sensitive to whether there is particle-hole symmetry. The predicted Friedel oscillations and the power-law decaying behavior of the local density of states (LDOS) near the defect are in good agreement with recent scanning tunneling microscope experiments on $\mathrm{Bi}_{2}\mathrm{Te}_{3}$. The high-energy LDOS of the surface states is also found to show the multi-periodic Friedel oscillations, caused by competing characteristic scattering processes.